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    Electrocatalysis of Ruthenium Nanoparticles-Decorated Hollow Carbon Spheres for the Conversion of LiS/LiS in Lithium-Sulfur Batteries. Pongilat Remith,Nallathamby Kalaiselvi ACS applied materials & interfaces Controlling "polysulfide dissolution" and pacifying "polysulfide shuttle" hold the key in developing a lithium-sulfur battery with superior electrochemical performance. Further, exploration of the concept of electrocatalysts plays a significant role in enhancing the electrochemical reversibility of polysulfides in lithium-sulfur battery. Herein, ruthenium nanoparticles-decorated porous, hollow carbon spheres have been successfully prepared and deployed as electrocatalyst as well as sulfur host in the lithium-sulfur battery assembly. Interaction of sulfur with ruthenium nanoparticles has been explained with appropriate electroanalytical and electrochemical characterization techniques. We observe that lithium-sulfur battery containing C-Ru-S cathode with a fixed sulfur loading exhibits a significantly improved capacity of 1200 mA h g at C/10 current rate for 100 cycles. Volume expansion-related issues are found to get addressed by the hollow structured carbon spheres, and the electrocatalytic activity will improve the reaction kinetics of the conversion of LiS to LiS and vice versa. 10.1021/acsami.8b09339
    Graphdiyne-Modified Polyimide Separator: A Polysulfide-Immobilizing Net Hinders the Shuttling of Polysulfides in Lithium-Sulfur Battery. Wang Yanqing,He Jianjiang,Zhang Zengqi,Liu Zhihong,Huang Changshui,Jin Yongcheng ACS applied materials & interfaces Graphdiyne (GDY), a new type of carbon material with an electron-rich conjugated structure, has been investigated as a separator coating layer to enhance the electrochemical performance of lithium-sulfur (Li-S) battery. Acetylenic bond (-C≡C-C≡C-) and benzene ring in the GDY coating layer are experimentally verified to reversibly attract the soluble lithium polysulfides by chemical adsorption during cycling. Meanwhile, the shuttle effect of soluble polysulfides is further physically restricted by the GDY coating layer due to the evenly distributed pores (5.42 Å) and a consistent interlayer spacing (3.65 Å) of GDY. Moreover, GDY is a conducting carbon skeleton with high Li mobility that can improve the rate performance. Hence, Li-S battery with an as-prepared GDY coating layer shows excellent electrochemical performances including superior specific capacity, excellent rate performance, and low capacity attenuation rate. The high initial discharge capacity of 1648.5 mA h g at 0.1C and 819.5 mA h g even at a high rate of 2C is achieved by this novel separator. The initial capacity of 1112.9 mA h g at 0.5C is retained to 816.7 mA h g after 200 cycles with a low attenuation rate of 0.13% per cycle. Compared with other coated separators, these results show that the GDY coating layer endows the separator with superior electrochemical performances for Li-S battery. 10.1021/acsami.9b11989
    Bioinspired Polysulfiphobic Artificial Interphase Layer on Lithium Metal Anodes for Lithium Sulfur Batteries. Shen Xiaowei,Qian Tao,Chen Pengpeng,Liu Jie,Wang Mengfan,Yan Chenglin ACS applied materials & interfaces The application of Li-S batteries suffers from many issues, polysulfide dissolution in particular. The fresh Li metal reacts with polysulfide continuously, which aggravates irregular Li plating/stripping behavior and decomposition of organic electrolyte resulting in short cycle life and low Coulombic efficiency. Nature has provided a lot of inspiration for human to realize structural construction and functional integration, as it does to battery design. In this report, learning from the hydrophobic property of natural species, a scaly polysulfiphobic artificial interphase layer are constructed on lithium metal anodes that can repel LiPS through the functional decylphosphonate groups that are proved by in operando XPS with Ar ion sputtering. Moreover, the obtained artificial interphase layer keeps dendrite-free morphology and restrains side reactions during cycling effectively. In situ XRD measurements are employed to demonstrate the inhibiting effect for decomposition of organic electrolyte. The as-obtained LDP-Li anodes exhibit outstanding electrochemical performance with the specific capacity of ∼1000 mAh g corresponding to Coulombic efficiency of nearly 99%, which shows great promise for the application of Li-S batteries. 10.1021/acsami.8b12093
    Free-Standing Porous Carbon Nanofiber/Carbon Nanotube Film as Sulfur Immobilizer with High Areal Capacity for Lithium-Sulfur Battery. Zhang Ye-Zheng,Zhang Ze,Liu Sheng,Li Guo-Ran,Gao Xue-Ping ACS applied materials & interfaces Low sulfur utilization and poor cycle life of the sulfur cathode with high sulfur loadings remain a great challenge for lithium-sulfur (Li-S) battery. Herein, the free-standing carbon film consisting of porous carbon nanofibers (PCNFs) and carbon nanotubes (CNTs) is successfully fabricated by the electrospinning technology. The PCNF/CNT film with three-dimensional and interconnected structure is promising for the uniformity of the high-loading sulfur, good penetration of the electrolyte, and reliable accommodation of volumetric expansion of the sulfur cathode. In addition, the abundant N/O-doped elements in PCNF/CNT film are helpful to chemically trap soluble polysulfides in the charge-discharge processes. Consequently, the obtained monolayer S/PCNF/CNT film as the cathode shows high specific capacity, excellent cycle stability, and rate stability with the sulfur loading of 3.9 mg cm. Moreover, the high areal capacity of 13.5 mA h cm is obtained for the cathode by stacking three S/PCNF/CNT layers with the high sulfur loading of 12 mg cm. The stacking-layered cathode with high sulfur loading provides excellent cycle stability, which is beneficial to fabricate high-energy-density Li-S battery in future. 10.1021/acsami.8b00190
    Polyelectrolyte Binder for Sulfur Cathode To Improve the Cycle Performance and Discharge Property of Lithium-Sulfur Battery. Yang Zhixiong,Li Rengui,Deng ZhengHua ACS applied materials & interfaces To achieve the higher capacity and the better cycle performance of the lithium-sulfur (L-S) batteries, a copolymer electrolyte prepared via emulsifier-free emulsion polymerization was used as the binder for the sulfur cathode in this study. This polyelectrolyte binder has uniform dispersion and good Li conductivity in the cathode that can improve the kinetics of sulfur electrochemical reactions. As a result, the capacity and cycle performance of the battery are improved evidently when the cell is discharged to 1.8 V. Moreover, when the cell is discharged to 1.5 V, the difficult deposition of LiS will take place easily at 1.75 V, and the difficult transformation from solid LiS to solid LiS will progress smoothly and completely during the voltage range of 1.55-1.75 V, too. The capacity of this L-S battery discharged to 1.5 V is as much as 1700 mAh g, which is very close to the theoretical value of sulfur cathode. The knowledge acquired in this study is valuable not only for the design of an efficient new polyelectrolyte binder for sulfur cathode but also the discovery that the discharge degree is the main fact that limits the capacity to reach its theoretical value. 10.1021/acsami.8b01163
    A high performance lithium-ion-sulfur battery with a free-standing carbon matrix supported Li-rich alloy anode. Zhang Tao,Hong Min,Yang Jun,Xu Zhixin,Wang Jiulin,Guo Yongsheng,Liang Chengdu Chemical science Although the lithium-sulfur battery exhibits high capacity and energy density, the cycling performance is severely retarded by dendrite formation and side-reactions of the lithium metal anode and the shuttle effect of polysulfides. Therefore, exploring lithium rich-alloy (or compound) anodes and suppressing the shuttling of polysulfides have become practical technical challenges for the commercialization of lithium-sulfur batteries. Here, a lithium ion sulfur full battery system combining a lithium-rich Li-Si alloy anode and sulfurized polyacrylonitrile (S@pPAN) cathode has been proposed. The free-standing CNF matrix supported Li-Si alloy anode is prepared by a simple and effective method, which is practical for scale-up production. The obtained Li-Si alloy anode demonstrates high cycling stability without dendrite growth, while the use of the S@pPAN cathode avoids the shuttle effect in carbonate electrolytes. The constructed Li-Si/S@pPAN battery could be cycled more than 1000 times at 1C and 3000 times at 3C, with a capacity fading rate of 0.01% and 0.03% per cycle. The exceptional performance should originate from the stable integrated anode structure and the excellent compatibility of the S@pPAN cathode and Li-Si alloy anode with carbonate electrolytes. 10.1039/c8sc02897d
    Design of Hollow Nanostructures for Energy Storage, Conversion and Production. Wang Jiangyan,Cui Yi,Wang Dan Advanced materials (Deerfield Beach, Fla.) Hollow nanostructures have shown great promise for energy storage, conversion, and production technologies. Significant efforts have been devoted to the design and synthesis of hollow nanostructures with diverse compositional and geometric characteristics in the past decade. However, the correlation between their structure and energy-related performance has not been reviewed thoroughly in the literature. Here, some representative examples of designing hollow nanostructure to effectively solve the problems of energy-related technologies are highlighted, such as lithium-ion batteries, lithium-metal anodes, lithium-sulfur batteries, supercapacitors, dye-sensitized solar cells, electrocatalysis, and photoelectrochemical cells. The great effect of structure engineering on the performance is discussed in depth, which will benefit the better design of hollow nanostructures to fulfill the requirements of specific applications and simultaneously enrich the diversity of the hollow nanostructure family. Finally, future directions of hollow nanostructure design to solve emerging challenges and further improve the performance of energy-related technologies are also provided. 10.1002/adma.201801993
    Two-Dimensional Arrays of Transition Metal Nitride Nanocrystals. Xiao Xu,Wang Hao,Bao Weizhai,Urbankowski Patrick,Yang Long,Yang Yao,Maleski Kathleen,Cui Linfan,Billinge Simon J L,Wang Guoxiu,Gogotsi Yury Advanced materials (Deerfield Beach, Fla.) The synthesis of low-dimensional transition metal nitride (TMN) nanomaterials is developing rapidly, as their fundamental properties, such as high electrical conductivity, lead to many important applications. However, TMN nanostructures synthesized by traditional strategies do not allow for maximum conductivity and accessibility of active sites simultaneously, which is a crucial factor for many applications in plasmonics, energy storage, sensing, and so on. Unique interconnected two-dimensional (2D) arrays of few-nanometer TMN nanocrystals not only having electronic conductivity in-plane, but also allowing transport of ions and electrolyte through the porous nanosheets, which are obtained by topochemical synthesis on the surface of a salt template, are reported. As a demonstration of their application in a lithium-sulfur battery, it is shown that 2D arrays of several nitrides can achieve a high initial capacity of >1000 mAh g at 0.2 C and only about 13% degradation over 1000 cycles at 1 C under a high areal sulfur loading (>5 mg cm ). 10.1002/adma.201902393
    Lithiophilic LiC Layers on Carbon Hosts Enabling Stable Li Metal Anode in Working Batteries. Shi Peng,Li Tao,Zhang Rui,Shen Xin,Cheng Xin-Bing,Xu Rui,Huang Jia-Qi,Chen Xiao-Ru,Liu He,Zhang Qiang Advanced materials (Deerfield Beach, Fla.) Lithium (Li) metal-based battery is among the most promising candidates for next-generation rechargeable high-energy-density batteries. Carbon materials are strongly considered as the host of Li metal to relieve the powdery/dendritic Li formation and large volume change during repeated cycles. Herein, we describe the formation of a thin lithiophilic LiC layer between carbon fibers (CFs) and metallic Li in Li/CF composite anode obtained through a one-step rolling method. An electron deviation from Li to carbon elevates the negativity of carbon atoms after Li intercalation as LiC , which renders stronger binding between carbon framework and Li ions. The Li/CF | Li/CF batteries can operate for more than 90 h with a small polarization voltage of 120 mV at 50% discharge depth. The Li/CF | sulfur pouch cell exhibits a high discharge capacity of 3.25 mAh cm and a large capacity retention rate of 98% after 100 cycles at 0.1 C. It is demonstrated that the as-obtained Li/CF composite anode with lithiophilic LiC layers can effectively alleviate volume expansion and hinder dendritic and powdery morphology of Li deposits. This work sheds fresh light on the role of interfacial layers between host structure and Li metal in composite anode for long-lifespan working batteries. 10.1002/adma.201807131
    Boosting potassium-ion batteries by few-layered composite anodes prepared via solution-triggered one-step shear exfoliation. Liu Yajie,Tai Zhixin,Zhang Jian,Pang Wei Kong,Zhang Qing,Feng Haifeng,Konstantinov Konstantin,Guo Zaiping,Liu Hua Kun Nature communications Earth-abundant potassium is a promising alternative to lithium in rechargeable batteries, but a pivotal limitation of potassium-ion batteries is their relatively low capacity and poor cycling stability. Here, a high-performance potassium-ion battery is achieved by employing few-layered antimony sulfide/carbon sheet composite anode fabricated via one-step high-shear exfoliation in ethanol/water solvent. Antimony sulfide with few-layered structure minimizes the volume expansion during potassiation and shortens the ion transport pathways, thus enhancing the rate capability; while carbon sheets in the composite provide electrical conductivity and maintain the electrode cycling stability by trapping the inevitable by-product, elemental sulfur. Meanwhile, the effect of the exfoliation solvent on the fabrication of two-dimensional antimony sulfide/carbon is also investigated. It is found that water facilitates the exfoliation by lower diffusion barrier along the [010] direction of antimony sulfide, while ethanol in the solvent acts as the carbon source for in situ carbonization. 10.1038/s41467-018-05786-1
    Elaboration of Aggregated Polysulfide Phases: From Molecules to Large Clusters and Solid Phases. Xiao Jiewen,Zhou Guangmin,Chen Hetian,Feng Xiang,Legut Dominik,Fan Yanchen,Wang Tianshuai,Cui Yi,Zhang Qianfan Nano letters With the increasing strategies aimed at repressing shuttle problems in the lithium-sulfur battery, dissolved contents of polysulfides are significantly reduced. Except for solid-state LiS and LiS, aggregated phases of polysulfides remain unexplored, especially in well confined cathode material systems. Here, we report a series of nanosize polysulfide clusters and solid phases from an atomic perspective. The calculated phase diagram and formation energy evolution process demonstrate their stabilities and cohesive tendency. It is interesting to find that LiS can stay in the solid state and contains short S chains, further leading to the unique stability and dense structure. Simulated electronic properties indicate reduced band gaps when polysulfides are aggregated, especially for solid phase LiS with a band gap as low as 0.47 eV. Their dissolution behavior and conversion process are also investigated, which provides a more realistic model and gives further suggestions on the future design of the lithium-sulfur battery. 10.1021/acs.nanolett.9b03297
    Electrochemically primed functional redox mediator generator from the decomposition of solid state electrolyte. Li Matthew,Bai Zhengyu,Li Yejing,Ma Lu,Dai Alvin,Wang Xuefeng,Luo Dan,Wu Tianpin,Liu Ping,Yang Lin,Amine Khalil,Chen Zhongwei,Lu Jun Nature communications Recent works into sulfide-type solid electrolyte materials have attracted much attention among the battery community. Specifically, the oxidative decomposition of phosphorus and sulfur based solid state electrolyte has been considered one of the main hurdles towards practical application. Here we demonstrate that this phenomenon can be leveraged when lithium thiophosphate is applied as an electrochemically "switched-on" functional redox mediator-generator for the activation of commercial bulk lithium sulfide at up to 70 wt.% lithium sulfide electrode content. X-ray adsorption near-edge spectroscopy coupled with electrochemical impedance spectroscopy and Raman indicate a catalytic effect of generated redox mediators on the first charge of lithium sulfide. In contrast to pre-solvated redox mediator species, this design decouples the lithium sulfide activation process from the constraints of low electrolyte content cell operation stemming from pre-solvated redox mediators. Reasonable performance is demonstrated at strict testing conditions. 10.1038/s41467-019-09638-4
    Mechanism Investigation of High-Performance Li-Polysulfide Batteries Enabled by Tungsten Disulfide Nanopetals. Huang Shaozhuan,Wang Ye,Hu Junping,Lim Yew Von,Kong Dezhi,Zheng Yun,Ding Meng,Pam Mei Er,Yang Hui Ying ACS nano Understanding the reaction kinetics and mechanism of Li-polysulfide batteries is critical in designing advanced host materials for improved performance. However, up to now, the reaction mechanism within the Li-polysulfide batteries is still unclear. Herein, we study the reaction mechanism of a high-performance Li-polysulfide battery by in situ X-ray diffraction (XRD) and density functional theory (DFT) calculations based on a multifunctional host material composed of WS nanopetals embedded in rGO-CNT (WS-rGO-CNT) aerogel. The WS nanopetal serves as a "catalytic center" to chemically bond the polysulfides and accelerate the polysulfide redox reactions, and the 3D porous rGO-CNT scaffold provides fast and efficient e/Li transportation. Thus, the resulting WS-rGO-CNT aerogel accommodating the polysulfide catholyte enables a stable cycling performance, excellent rate capability (614 mAh g at 2 C), and a high areal capacity (6.6 mAh cm at 0.5 C). In situ XRD results reveal that the LiS starts to form at an early stage of discharge (at a depth of 25% of the lower voltage plateau) during the discharge process, and β-S nucleation begins before the upper voltage plateau during the recharge process, which are different from the conventional Li-S battery. Moreover, the WS itself could be lithiated/delithiated during the cycling, making the lithiated WS (Li WS, 0 ≤ x ≤ 0.3) a real host material for Li-polysulfide batteries. DFT calculations suggest that Li WS (0 ≤ x ≤ 0.3) exhibits moderate binding/anchoring interactions toward polysulfides with adsorption energies of 0.51-1.4 eV. Our work reveals the reaction mechanism of the Li-polysulfide batteries and indicates that the lithiated host plays an important role in trapping the polysulfides. 10.1021/acsnano.8b04857
    Suppressing Li Metal Dendrites Through a Solid Li-Ion Backup Layer. Salvatierra Rodrigo V,López-Silva Gladys A,Jalilov Almaz S,Yoon Jongwon,Wu Gang,Tsai Ah-Lim,Tour James M Advanced materials (Deerfield Beach, Fla.) The growing demand for sustainable and off-grid energy storage is reviving the attempts to use Li metal as the anode in the next generation of batteries. However, the use of Li anodes is hampered due to the growth of Li dendrites upon charging and discharging, which compromises the life and safety of the battery. Here, it is shown that lithiated multiwall carbon nanotubes (Li-MWCNTs) act as a controlled Li diffusion interface that suppresses the growth of Li dendrites by regulating the Li ion flux during charge/discharge cycling at current densities between 2 and 4 mA cm . A full Li-S cell is fabricated to showcase the versatility of the protected Li anode with the Li-MWCNT interface, where the full cells could support pulse discharges at high currents and over 450 cycles at different rates with coulombic efficiencies close to 99.9%. This work indicates that carbon materials in lithiated forms can be an effective and simple approach to the stabilization of Li metal anodes. 10.1002/adma.201803869
    Functional Two-Dimensional Coordination Polymeric Layer as a Charge Barrier in Li-S Batteries. Huang Jing-Kai,Li Mengliu,Wan Yi,Dey Sukumar,Ostwal Mayur,Zhang Daliang,Yang Chih-Wen,Su Chun-Jen,Jeng U-Ser,Ming Jun,Amassian Aram,Lai Zhiping,Han Yu,Li Sean,Li Lain-Jong ACS nano Ultrathin two-dimensional (2D) polymeric layers are capable of separating gases and molecules based on the reported size exclusion mechanism. What is equally important but missing today is an exploration of the 2D layers with charge functionality, which enables applications using the charge exclusion principle. This work demonstrates a simple and scalable method of synthesizing a free-standing 2D coordination polymer Zn(benzimidazolate)(OH) at the air-water interface. The hydroxyl (-OH) groups are stoichiometrically coordinated and implement electrostatic charges in the 2D structures, providing powerful functionality as a charge barrier. Electrochemical performance of the Li-S battery shows that the Zn(benzimidazolate)(OH) coordination polymer layers efficiently mitigate the polysulfide shuttling effects and largely enhance the battery capacity and cycle performance. The synthesis of the proposed coordination polymeric layers is simple, scalable, cost saving, and promising for practical use in batteries. 10.1021/acsnano.7b08223
    Before Li Ion Batteries. Winter Martin,Barnett Brian,Xu Kang Chemical reviews This Review covers a sequence of key discoveries and technical achievements that eventually led to the birth of the lithium-ion battery. In doing so, it not only sheds light on the history with the advantage of contemporary hindsight but also provides insight and inspiration to aid in the ongoing quest for better batteries of the future. A detailed retrospective on ingenious designs, accidental discoveries, intentional breakthroughs, and deceiving misconceptions is given: from the discovery of the element lithium to its electrochemical synthesis; from intercalation host material development to the concept of dual-intercalation electrodes; and from the misunderstanding of intercalation behavior into graphite to the comprehension of interphases. The onerous demands of bringing all critical components (anode, cathode, electrolyte, solid-electrolyte interphases), each of which possess unique chemistries, into a sophisticated electrochemical device reveal that the challenge of interfacing these originally incongruent components often outweighs the individual merits and limits in their own properties. These important lessons are likely to remain true for the more aggressive battery chemistries of future generations, ranging from a revisited Li-metal anode, to conversion-reaction type chemistries such as Li/sulfur, Li/oxygen, and metal fluorides, and to bivalent cation intercalations. 10.1021/acs.chemrev.8b00422
    Exploring Chemical, Mechanical, and Electrical Functionalities of Binders for Advanced Energy-Storage Devices. Chen Hao,Ling Min,Hencz Luke,Ling Han Yeu,Li Gaoran,Lin Zhan,Liu Gao,Zhang Shanqing Chemical reviews Tremendous efforts have been devoted to the development of electrode materials, electrolytes, and separators of energy-storage devices to address the fundamental needs of emerging technologies such as electric vehicles, artificial intelligence, and virtual reality. However, binders, as an important component of energy-storage devices, are yet to receive similar attention. Polyvinylidene fluoride (PVDF) has been the dominant binder in the battery industry for decades despite several well-recognized drawbacks, i.e., limited binding strength due to the lack of chemical bonds with electroactive materials, insufficient mechanical properties, and low electronic and lithium-ion conductivities. The limited binding function cannot meet inherent demands of emerging electrode materials with high capacities such as silicon anodes and sulfur cathodes. To address these concerns, in this review we divide the binding between active materials and binders into two major mechanisms: mechanical interlocking and interfacial binding forces. We review existing and emerging binders, binding technology used in energy-storage devices (including lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, and supercapacitors), and state-of-the-art mechanical characterization and computational methods for binder research. Finally, we propose prospective next-generation binders for energy-storage devices from the molecular level to the macro level. Functional binders will play crucial roles in future high-performance energy-storage devices. 10.1021/acs.chemrev.8b00241
    Low Cost Metal Carbide Nanocrystals as Binding and Electrocatalytic Sites for High Performance Li-S Batteries. Zhou Fei,Li Zheng,Luo Xuan,Wu Tong,Jiang Bin,Lu Lei-Lei,Yao Hong-Bin,Antonietti Markus,Yu Shu-Hong Nano letters Lithium sulfur (Li-S) batteries are considered as promising energy storage systems for the next generation of batteries due to their high theoretical energy densities and low cost. Much effort has been made to improve the practical energy densities and cycling stability of Li-S batteries via diverse designs of materials nanostructure. However, achieving simultaneously good rate capabilities and stable cycling of Li-S batteries is still challenging. Herein, we propose a strategy to utilize a dual effect of metal carbide nanoparticles decorated on carbon nanofibers (MC NPs-CNFs) to realize high rate performance, low hysteresis, and long cycling stability of Li-S batteries in one system. The adsorption experiments of lithium polysulfides (LiPS) to MC NPs and corresponding theoretical calculations demonstrate that LiPS are likely to be adsorbed and diffused on the surface of MC NPs because of their moderate chemical bonding. MC NPs turn out to have also an electrocatalytic role and accelerate electrochemical redox reactions of LiPS, as proven by cyclic voltammetry analysis. The fabricated Li-S batteries based on the WC NPs-CNFs hybrid electrodes display not only high specific capacity of 1200 mAh/g at 0.2C but also excellent rate performance and cycling stability, for example, a model setup can be operated at 1C for 500 cycles maintaining a final specific capacity of 605 mAh/g with a degradation rate as low as 0.06%/cycle. 10.1021/acs.nanolett.7b04505
    Bacteria-Derived Biological Carbon Building Robust Li-S Batteries. Wang Tao,Zhu Jian,Wei Zengxi,Yang Hongguan,Ma Zhaolin,Ma Ruifang,Zhou Jian,Yang Yuhua,Peng Lele,Fei Huilong,Lu Bingan,Duan Xiangfeng Nano letters Lithium sulfur (Li-S) batteries are attracting increasing interest for high-density energy storage. However, the practical application is limited by the rapid capacity fading over repeated charge/discharge cycles which is largely attributed to the formation and shuttling of soluble polysulfide species. To address these issues, we develop a hierarchical structure composite with triple protection strategy via graphene, organic conductor PEDOT, and nitrogen and phosphorus codoped biological carbon to encapsulate sulfur species (GOC@NPBCS). This unique hierarchical structure can effectively immobilize the sulfur species while at the same time improve the electrical conductivity and ensure efficient lithium ion transport to enable excellent Li-S battery performance. In particular, the biological carbon derived from natural bacteria features inherent nitrogen and phosphorus codoping with a strong absorption to lithium polysulfides, which can greatly suppress the dissolution and shuttling of polysulfides that are responsible for rapid capacity fading. With these synergistic effects, the GOC@NPBCS cathode exhibits exceptionally stable cycling stability (an ultralow capacity fading rate of 0.045% per cycle during 1000 cycles at the current rate of 5 C), high specific capacity (1193.8 mAh g at 0.5 C based on sulfur weight), and excellent rate capability. 10.1021/acs.nanolett.9b00996
    Self-heating-induced healing of lithium dendrites. Li Lu,Basu Swastik,Wang Yiping,Chen Zhizhong,Hundekar Prateek,Wang Baiwei,Shi Jian,Shi Yunfeng,Narayanan Shankar,Koratkar Nikhil Science (New York, N.Y.) Lithium (Li) metal electrodes are not deployable in rechargeable batteries because electrochemical plating and stripping invariably leads to growth of dendrites that reduce coulombic efficiency and eventually short the battery. It is generally accepted that the dendrite problem is exacerbated at high current densities. Here, we report a regime for dendrite evolution in which the reverse is true. In our experiments, we found that when the plating and stripping current density is raised above ~9 milliamperes per square centimeter, there is substantial self-heating of the dendrites, which triggers extensive surface migration of Li. This surface diffusion heals the dendrites and smoothens the Li metal surface. We show that repeated doses of high-current-density healing treatment enables the safe cycling of Li-sulfur batteries with high coulombic efficiency. 10.1126/science.aap8787
    Infinitesimal sulfur fusion yields quasi-metallic bulk silicon for stable and fast energy storage. Ryu Jaegeon,Seo Ji Hui,Song Gyujin,Choi Keunsu,Hong Dongki,Wang Chongmin,Lee Hosik,Lee Jun Hee,Park Soojin Nature communications A fast-charging battery that supplies maximum energy is a key element for vehicle electrification. High-capacity silicon anodes offer a viable alternative to carbonaceous materials, but they are vulnerable to fracture due to large volumetric changes during charge-discharge cycles. The low ionic and electronic transport across the silicon particles limits the charging rate of batteries. Here, as a three-in-one solution for the above issues, we show that small amounts of sulfur doping (<1 at%) render quasi-metallic silicon microparticles by substitutional doping and increase lithium ion conductivity through the flexible and robust self-supporting channels as demonstrated by microscopy observation and theoretical calculations. Such unusual doping characters are enabled by the simultaneous bottom-up assembly of dopants and silicon at the seed level in molten salts medium. This sulfur-doped silicon anode shows highly stable battery cycling at a fast-charging rate with a high energy density beyond those of a commercial standard anode. 10.1038/s41467-019-10289-8
    Metal-Organic Frameworks/Conducting Polymer Hydrogel Integrated Three-Dimensional Free-Standing Monoliths as Ultrahigh Loading Li-S Battery Electrodes. Liu Borui,Bo Renheng,Taheri Mahdiar,Di Bernardo Iolanda,Motta Nunzio,Chen Hongjun,Tsuzuki Takuya,Yu Guihua,Tricoli Antonio Nano letters The lithium-sulfur (Li-S) system is a promising material for the next-generation of high energy density batteries with application extending from electrical vehicles to portable devices and aeronautics. Despite progress, the energy density of current Li-S technologies is still below that of conventional intercalation-type cathode materials due to limited stability and utilization efficiency at high sulfur loading. Here, we present a conducting polymer hydrogel integrated highly performing free-standing three-dimensional (3D) monolithic electrode architecture for Li-S batteries with superior electrochemical stability and energy density. The electrode layout consists of a highly conductive three-dimensional network of N,P codoped carbon with well-dispersed metal-organic framework nanodomains of ZIF-67 and HKUST-1. The hierarchical monolithic 3D carbon networks provide an excellent environment for charge and electrolyte transport as well as mechanical and chemical stability. The electrically integrated MOF nanodomains significantly enhance the sulfur loading and retention capabilities by inhibiting the release of lithium polysulfide specificities as well as improving the charge transfer efficiency at the electrolyte interface. Our optimal 3D carbon-HKUST-1 electrode architecture achieves a very high areal capacity of >16 mAh cm and volumetric capacity () of 1230.8 mAh cm with capacity retention of 82% at 0.2C for over 300 cycles, providing an attractive candidate material for future high-energy density Li-S batteries. 10.1021/acs.nanolett.9b01033
    Improving a Mg/S Battery with YCl Additive and Magnesium Polysulfide. Xu Yan,Zhou Guangmin,Zhao Shuyang,Li Wanfei,Shi Feifei,Li Jia,Feng Jun,Zhao Yuxing,Wu Yang,Guo Jinghua,Cui Yi,Zhang Yuegang Advanced science (Weinheim, Baden-Wurttemberg, Germany) Rechargeable magnesium/sulfur (Mg/S) batteries are widely regarded as one of the alternatives to lithium-ion batteries. However, a key factor restricting their application is the lack of suitable electrolyte. Herein, an electrolyte additive that can reduce the polarization voltage is developed and 98.7% coulombic efficiency is realized. The as-prepared Mg-ion electrolyte exhibits excellent Mg plating/stripping performance with a low overpotential of 0.11 V for plating process, and high anodic stability up to 3.0 V (vs Mg/Mg). When it is coupled with magnesium polysulfide, which has high reactivity and is homogeneously distributed on carbon matrix, the Mg/S cells deliver a good cycling stability with a high discharge capacity over 1000 mAh g for more than 50 cycles. 10.1002/advs.201800981
    Transitional Metal Catalytic Pyrite Cathode Enables Ultrastable Four-Electron-Based All-Solid-State Lithium Batteries. Wan Hongli,Liu Gaozhan,Li Yanle,Weng Wei,Mwizerwa Jean Pierre,Tian Ziqi,Chen Liang,Yao Xiayin ACS nano All-solid-state batteries can enable reversible four lithium ion storage for pyrite (FeS) at a cutoff voltage of 1.0-3.0 V. However, strain/stress concentration generating electrode pulverization and sluggish electrochemical reaction of lithium sulfide and sulfur will affect the long cycling stability of the battery. Through experiments and density functional theory (DFT) calculations, it is proved that nanostructure engineering and electronic conduction improvement with introduction of catalytic cobalt can effectively improve the electrochemical activity of FeS. The optimized loose structured CoFeS based all-solid-state lithium batteries show reversible capacities of 860.5, 797.7, 685.8, and 561.8 mAh g after five cycles at 100, 200, 500, and 1000 mA g, respectively, and a stable capacity of 543.5 mAh g can be maintained after cycling at a current density of 500 mA g for 100 cycles. TEM and Raman results reveal that, after the first cycle, the reversible reaction 2LiS + Fe ↔ FeS + (2 - )S + 4Li + 4 proceeds from the following cycles onward, while nanocrystalline mackinawite FeS, Fe(III)-containing mackinawite FeS, and FeS are generated after the first discharge-charge process. This work provides a facile method for improving the electrochemical performance for multi-electron reaction mechanism based all-solid-state lithium batteries. 10.1021/acsnano.9b04538
    Developing a "Water-Defendable" and "Dendrite-Free" Lithium-Metal Anode Using a Simple and Promising GeCl Pretreatment Method. Liao Kaiming,Wu Shichao,Mu Xiaowei,Lu Qian,Han Min,He Ping,Shao Zongping,Zhou Haoshen Advanced materials (Deerfield Beach, Fla.) Lithium metal is an ultimate anode in "next-generation" rechargeable batteries, such as Li-sulfur batteries and Li-air (Li-O ) batteries. However, uncontrollable dendritic Li growth and water attack have prevented its practical applications, especially for open-system Li-O batteries. Here, it is reported that the issues can be addressed via the facile process of immersing the Li metal in organic GeCl -THF steam for several minutes before battery assembly. This creates a 1.5 µm thick protection layer composed of Ge, GeO , Li CO , LiOH, LiCl, and Li O on Li surface that allows stable cycling of Li electrodes both in Li-symmetrical cells and Li-O cells, especially in "moist" electrolytes (with 1000-10 000 ppm H O) and humid O atmosphere (relative humidity (RH) of 45%). This work illustrates a simple and effective way for the unfettered development of Li-metal-based batteries. 10.1002/adma.201705711
    Spatiotemporal Quantification of Lithium both in Electrode and in Electrolyte with Atomic Precision via Operando Neutron Absorption. Harks Peter-Paul R M L,Verhallen Tomas W,George Chandramohan,van den Biesen Jan Karel,Liu Qian,Wagemaker Marnix,Mulder Fokko M Journal of the American Chemical Society The commercial uptake of lithium-sulfur (Li-S) batteries is undermined by their rapid performance decay and short cycle life. These problems originate from the dissolution of lithium polysulfide in liquid electrolytes, causing charge and active material to shuttle between electrodes. The dynamics of intractable polysulfide migration at different length scales often tend to escape the probing ability of many analytical techniques. Spatial and temporal visualization of Li in Li-S electrodes and direct mechanistic understanding of how polysulfides are regulated across Li-S batteries starting from current collector and active layer coating to electrode-electrolyte interface are still lacking. To address this we employ neutron depth profiling across Li-S electrodes using the naturally occurring isotope, Li, which yields direct spatial information on Li-S electrochemistry. Using three types of Li-S electrodes, namely, carbon-sulfur, carbon-sulfur with 10% lithium titanium oxide (LTO), and carbon-sulfur with LTO membrane, we provide direct evidence for the migration, adsorption, and confinement of polysulfides in Li-S cells at work. Our findings further provide insights into the dynamics of polysulfide dissolution and re-utilization in relation to Li-S battery capacity and longevity to aid rational electrode designs toward high-energy, safe, and low-cost batteries. 10.1021/jacs.9b05993
    Understanding Conversion-Type Electrodes for Lithium Rechargeable Batteries. Yu Seung-Ho,Feng Xinran,Zhang Na,Seok Jeesoo,Abruña Héctor D Accounts of chemical research The need/desire to lower the consumption of fossil fuels and its environmental consequences has reached unprecedented levels in recent years. A global effort has been undertaken to develop advanced renewable energy generation and especially energy storage technologies, as they would enable a dramatic increase in the effective and efficient use of renewable (and often intermittent) energy sources. The development of electrical energy storage (EES) technologies with high energy and power densities, long life, low cost, and safe use represents a challenge from both the fundamental science and technological application points of view. While the advent and broad deployment of lithium-ion batteries (LIBs) has dramatically changed the EES landscape, their performance metrics need to be greatly enhanced to keep pace with the ever-increasing demands imposed by modern consumer electronics and especially the emerging automotive markets. Current battery technologies are mostly based on the use of a transition metal oxide cathode (e.g., LiCoO, LiFePO, or LiNiMnCoO) and a graphite anode, both of which depend on intercalation/insertion of lithium ions for operation. While the cathode material currently limits the battery capacity and overall energy density, there is a great deal of interest in the development of high-capacity cathode materials as well as anode materials. Conversion reaction materials have been identified/proposed as potentially high-energy-density alternatives to intercalation-based materials. However, conversion reaction materials react during lithiation to form entirely new products, often with dramatically changed structure and chemistry, by reaction mechanisms that are still not completely understood. This makes it difficult to clearly distinguish the limitations imposed by the mechanism and practical losses from initial particle morphology, synthetic approaches, and electrode preparations. Transition metal compounds such as transition metal oxides, sulfides, fluorides, phosphides, and nitrides can undergo conversion reactions yielding materials with high theoretical capacity (generally from 500 to 1500 mA h g). In particular, a number of transition metal oxides and sulfides have shown excellent electrochemical properties as high-capacity anode materials. In addition, some transition metal fluorides have shown great potential as cathode materials for Li rechargeable batteries. In this Account we present mechanistic studies, with emphasis on the use of operando methods, of selected examples of conversion-type materials as both potentially high-energy-density anodes and cathodes in EES applications. We also include examples of the conceptually similar conversion-type reactions involving chalcogens and halogens, with emphasis on the Li-S system. In this case we focus on the problems arising from the low electrical conductivities of elemental sulfur and LiS and the "redox shuttle" phenomena of polysulfides. In addition to mechanistic insights from the use of operando methods, we also cover several key strategies in electrode materials design such as controlling the size, morphology, composition, and architecture. 10.1021/acs.accounts.7b00487
    Nonlithium Metal-Sulfur Batteries: Steps Toward a Leap. Hong Xiaodong,Mei Jun,Wen Lei,Tong Yueyu,Vasileff Anthony J,Wang Liqun,Liang Ji,Sun Ziqi,Dou Shi Xue Advanced materials (Deerfield Beach, Fla.) Present mobile devices, transportation tools, and renewable energy technologies are more dependent on newly developed battery chemistries than ever before. Intrinsic properties, such as safety, high energy density, and cheapness, are the main objectives of rechargeable batteries that have driven their overall technological progress over the past several decades. Unfortunately, it is extremely hard to achieve all these merits simultaneously at present. Alternatively, exploration of the most suitable batteries to meet the specific requirements of an individual application tends to be a more reasonable and easier choice now and in the near future. Based on this concept, here, a range of promising alternatives to lithium-sulfur batteries that are constructed with non-Li metal anodes (e.g., Na, K, Mg, Ca, and Al) and sulfur cathodes are discussed. The systems governed by these new chemistries offer high versatility in meeting the specific requirements of various applications, which is directly linked with the broad choice in battery chemistries, materials, and systems. Herein, the operating principles, materials, and remaining issues for each targeted battery characteristics are comprehensively reviewed. By doing so, it is hoped that their design strategies are illustrated and light is shed on the future exploration of new metal-sulfur batteries and advanced materials. 10.1002/adma.201802822
    A pyrolyzed polyacrylonitrile/selenium disulfide composite cathode with remarkable lithium and sodium storage performances. Li Zhen,Zhang Jintao,Lu Yan,Lou Xiong Wen David Science advances As a special class of cathode materials for lithium-sulfur batteries, pyrolyzed polyacrylonitrile/sulfur (pPAN/S) can completely solve the polysulfide dissolution problem and deliver reliable performance. However, the applicable S contents of pPAN/S are usually lower than 50 weight % (wt %), and their capacity utilizations are not sufficient, both of which greatly limit their energy densities for commercial applications. We report a pyrolyzed polyacrylonitrile/selenium disulfide (pPAN/SeS) composite with dramatically enhanced active material content (63 wt %) and superior performances for both lithium and sodium storage. As a result, pPAN/SeS delivers high capacity of >1100 mAh g at 0.2 A g for Li storage with extremely stable cycle life over 2000 cycles at 4.0 A g. Moreover, when applied in a room temperature Na-SeS battery, pPAN/SeS achieves superior capacity of >900 mAh g at 0.1 A g and delivers prolonged cycle life over 400 cycles at 1.0 A g. 10.1126/sciadv.aat1687
    Room-Temperature Potassium-Sulfur Batteries Enabled by Microporous Carbon Stabilized Small-Molecule Sulfur Cathodes. Xiong Peixun,Han Xinpeng,Zhao Xinxin,Bai Panxing,Liu Yang,Sun Jie,Xu Yunhua ACS nano Potassium-sulfur (K-S) batteries are a promising alternative to lithium ion batteries for large-area energy storage applications, owing to their high capacity and inexpensiveness, but they have been seldom investigated. Here we report room-temperature K-S batteries utilizing a microporous carbon-confined small-molecule sulfur composite cathode. The synergetic effects of the strong confinement of microporous carbon matrix and the small-molecule sulfur structure can effectually eliminate the formation of soluble polysulfides and ensure a reversible capacity of 1198.3 mA h g and retain 72.5% after 150 cycles with a Coulombic efficiency of ∼97%. The potassium-storage mechanism was investigated by X-ray photoelectron spectroscopy analysis and theoretical calculations. The results suggest that KS is the final potassiation product along with the reaction of 2K + S ↔ KS, giving a theoretical capacity of 1675 mA h g. Our findings not only provide an effective strategy to fabricate high-performance room-temperature K-S batteries but also offer a basic comprehension of the potassium storage mechanism of sulfur cathode materials. 10.1021/acsnano.8b09503
    Nitrofullerene, a C-based Bifunctional Additive with Smoothing and Protecting Effects for Stable Lithium Metal Anode. Jiang Zhipeng,Zeng Ziqi,Yang Chengkai,Han Zhilong,Hu Wei,Lu Jing,Xie Jia Nano letters Practical applications of lithium metal anodes are gravely impeded by inhomogeneous lithium deposition, which results in dendrite growth. Electrolyte additives are proven to be effective in improving performance but usually serve only a single function. Herein, nitrofullerene is introduced as a bifunctional additive with a smoothing effect and forms a protective solid electrolyte interphase (SEI) layer on stable lithium metal anodes. By design, nitro-C can gather on electrode protuberances via electrostatic interactions and then be reduced to NO and insoluble C. Next, the C anchors on the uneven groove of the lithium surface, resulting in a homogeneous distribution of Li ions. Finally, NO anions can react with metallic Li to build a compact and stable SEI with high ion transport. With a 5 mM nitro-C additive, Li-Li symmetric cells show superior cycle stability in both carbonate and ether electrolytes, Li-sulfur batteries with a high cathode loading (10.6 mg cm, 6 mAh cm) can achieve improved cycle retention of 63.2% over 100 cycles in a carbonate electrolyte, and full cells paired with a high-areal-capacity LiNiCoMnO cathode (3.5 mAh cm) exhibit a significantly enhanced cycle lifespan even under lean electrolyte conditions. 10.1021/acs.nanolett.9b03562
    A Dual-Functional Conductive Framework Embedded with TiN-VN Heterostructures for Highly Efficient Polysulfide and Lithium Regulation toward Stable Li-S Full Batteries. Yao Yu,Wang Haiyun,Yang Hai,Zeng Sifan,Xu Rui,Liu Fanfan,Shi Pengcheng,Feng Yuezhan,Wang Kai,Yang Wenjin,Wu Xiaojun,Luo Wei,Yu Yan Advanced materials (Deerfield Beach, Fla.) Lithium-sulfur (Li-S) batteries are strongly considered as next-generation energy storage systems because of their high energy density. However, the shuttling of lithium polysulfides (LiPS), sluggish reaction kinetics, and uncontrollable Li-dendrite growth severely degrade the electrochemical performance of Li-S batteries. Herein, a dual-functional flexible free-standing carbon nanofiber conductive framework in situ embedded with TiN-VN heterostructures (TiN-VN@CNFs) as an advanced host simultaneously for both the sulfur cathode (S/TiN-VN@CNFs) and the lithium anode (Li/TiN-VN@CNFs) is designed. As cathode host, the TiN-VN@CNFs can offer synergistic function of physical confinement, chemical anchoring, and superb electrocatalysis of LiPS redox reactions. Meanwhile, the well-designed host with excellent lithiophilic feature can realize homogeneous lithium deposition for suppressing dendrite growth. Combined with these merits, the full battery (denoted as S/TiN-VN@CNFs || Li/TiN-VN@CNFs) exhibits remarkable electrochemical properties including high reversible capacity of 1110 mAh g after 100 cycles at 0.2 C and ultralong cycle life over 600 cycles at 2 C. Even with a high sulfur loading of 5.6 mg cm , the full cell can achieve a high areal capacity of 5.5 mAh cm at 0.1 C. This work paves a new design from theoretical and experimental aspects for fabricating high-energy-density flexible Li-S full batteries. 10.1002/adma.201905658
    Li S- or S-Based Lithium-Ion Batteries. Li Matthew,Chen Zhongwei,Wu Tianpin,Lu Jun Advanced materials (Deerfield Beach, Fla.) While members of the Li-S battery research community are becoming more conscious of the practical testing parameters, the widespread commercialization of S-based batteries is still far from realization. Particularly, the metallic Li used as the anode poses potential safety and cycle stability concerns. Alternatively, other S-battery configurations without a Li anode, i.e., lithium-ion, Li S, or S batteries, do not suffer from the same safety concerns and can possibly serve as better methods to bring room-temperature S-based battery technologies to industry. However, whether Li S or S will be used as the initiating cathode material remains unclear as each offers their own unique advantages and disadvantages. Here, both S and Li S as cathodes are briefly discussed and the key benefits of Li S are highlighted. 10.1002/adma.201801190
    Nanoporous Polymer Films with a High Cation Transference Number Stabilize Lithium Metal Anodes in Light-Weight Batteries for Electrified Transportation. Ma Lin,Fu Chengyin,Li Longjun,Mayilvahanan Karthik S,Watkins Tylan,Perdue Brian R,Zavadil Kevin R,Helms Brett A Nano letters To suppress dendrite formation in lithium metal batteries, high cation transference number electrolytes that reduce electrode polarization are highly desirable, but rarely available using conventional liquid electrolytes. Here, we show that liquid electrolytes increase their cation transference numbers (e.g., ∼0.2 to >0.70) when confined to a structurally rigid polymer host whose pores are on a similar length scale (0.5-2 nm) as the Debye screening length in the electrolyte, which results in a diffuse electrolyte double layer at the polymer-electrolyte interface that retains counterions and reject co-ions from the electrolyte due to their larger size. Lithium anodes coated with ∼1 μm thick overlayers of the polymer host exhibit both a low area-specific resistance and clear dendrite-suppressing character, as evident from their performance in Li-Li and Li-Cu cells as well as in post-mortem analysis of the anode's morphology after cycling. High areal capacity Li-S cells (4.9 mg cm; 8.2 mAh cm) implementing these high transference number polymer-hosted liquid electrolytes were remarkably stable, considering ∼24 μm of lithium was electroreversibly deposited in each cycle at a C-rate of 0.2. We further identified a scalable manufacturing path for these polymer-coated lithium electrodes, which are drop-in components for lithium metal battery manufacturing. 10.1021/acs.nanolett.8b05101
    Dandelion-like Mn/Ni Co-doped CoO/C Hollow Microspheres with Oxygen Vacancies for Advanced Lithium Storage. Li Qing,Zhao Yunhao,Liu Handing,Xu Pingdi,Yang Liting,Pei Ke,Zeng Qingwen,Feng Yuzhang,Wang Peng,Che Renchao ACS nano Hollow structures have attracted great attention based on the advantage to accommodate volume expansion. However, template removal usually results in structure destruction. Herein, dandelion-like Mn/Ni co-doped CoO/C hollow microspheres (CMNC-10h) are synthesized an Ostwald ripening process without templates. The high-angle annular dark field mapping images at the atomic level indicate the successful doping of Mn and Ni into CoO. an annular bright field image, oxygen vacancies induced by doping can be clearly observed. The residual two electrons in the oxygen vacancy site are highly delocalized, as confirmed by density functional theory calculations, effectively improving electrical conductivity. According to electron holography analysis, the dielectric polarization field in superficial regions of primary nanoparticles can facilitate insertion of Li ions into nanoparticles and thus enhance electrochemical kinetics. Combining those advantages, CMNC-10h demonstrates a high capacity of 1126 mAh g at 1 A g after 1000 cycles as anode material for a lithium-ion battery. Additionally, based on the strong adsorption toward polysulfide, the porous structure to accommodate sulfer/polysulfide, and the effects of oxygen vacancies to immobilize and catalyze polysulfide, CMNC-10h-S as cathode material for a lithium-sulfur battery also displays a high capacity of 642 mAh g after 500 cycles at 1 C. 10.1021/acsnano.9b06005
    Oxygen Vacancies on Layered Niobic Acid That Weaken the Catalytic Conversion of Polysulfides in Lithium-Sulfur Batteries. Xu Lingling,Zhao Hongyang,Sun Mingzi,Huang Bolong,Wang Jianwei,Xia Jiale,Li Na,Yin Dandan,Luo Meng,Luo Feng,Du Yaping,Yan Chunhua Angewandte Chemie (International ed. in English) Oxygen vacancies are usually considered to be beneficial in catalytic conversion of polysulfides in lithium-sulfur batteries. Now it is demonstrated that the conversion of polysulfides was hindered by oxygen vacancies on ultrathin niobic acid. The inferior performance induced by the oxygen vacancy was mainly attributed to the decreased electric conductivity as well as the weakened adsorption of polysulfides on the catalyst surface. This work shows that the care should be taken when designing a new catalyst for the lithium-sulfur battery using a defect-engineering strategy. 10.1002/anie.201905852
    Cerium Based Metal-Organic Frameworks as an Efficient Separator Coating Catalyzing the Conversion of Polysulfides for High Performance Lithium-Sulfur Batteries. Hong Xu-Jia,Song Chun-Lei,Yang Yan,Tan Hao-Chong,Li Guo-Hui,Cai Yue-Peng,Wang Hongxia ACS nano In this work, we demonstrate cerium (Ce) based metal-organic frameworks (MOFs) combined with carbon nanotubes (CNTs) to form Ce-MOF/CNT composites as separator coating material in the Li-S battery system, which showed excellent electrochemical performance even under high sulfur loading and much better capacity retention. At the sulfur loading of 2.5 mg/cm, initial specific capacity of 1021.8 mAh/g at 1C was achieved in the Li-S cell with the Ce-MOF-2/CNT coated separator, which was slowly reduced to 838.8 mAh/g after 800 cycles with a decay rate of only 0.022% and the Coulombic efficiency of nearly 100%. Even at a higher sulfur loading of 6 mg/cm, the cell based on Ce-MOF-2/CNT separator coating still exhibited excellent performance with initial specific capacity of 993.5 mAh/g at 0.1 C. After 200 cycles, the specific capacity of 886.4 mAh/g was still retained. The excellent performance is ascribed to the efficient adsorption of the Ce-MOF-2 to LiS species and its catalytic effect toward conversion of polysulfides, resulting in suppressed shuttle effect of polysulfides in the Li-S batteries. 10.1021/acsnano.8b08155
    Organosulfides: An Emerging Class of Cathode Materials for Rechargeable Lithium Batteries. Wang Dan-Yang,Guo Wei,Fu Yongzhu Accounts of chemical research Lithium-ion batteries have received significant attention over the last decades due to the wide application of portable electronics and increasing deployment of electric vehicles. In order to further increase the energy density of batteries and overcome the capacity limitations (<250 mAh g) of inorganic cathode materials, it is imperative to explore new cathode materials for rechargeable lithium batteries. Organic compounds including organic carbonyl, radicals, and organosulfides are promising as they have advantages of high capacities, abundant resources, and tunable structures. In the 1980s, a few organosulfides, in particular organodisulfides, as cathode materials were studied to a certain extent in rechargeable lithium batteries. However, they showed low capacities and poor cycling performance, which made them unappealing then in comparison to transition metal oxide cathode materials. As a result, organosulfides have not been extensively studied like other cathode materials including organic carbonyls and radicals. In recent years, organosulfides with long sulfur chains (e.g., trisulfide, tetrasulfide, pentasulfide, etc.) in the structures have been receiving more attention in conjunction with the development of lithium-sulfur batteries. As a major class of sulfur derivatives, they have versatile structures and unique properties in comparison with elemental sulfur. In this Account, we first generalize the working principles of organosulfides in lithium batteries. We then discuss organosulfide molecules, which have precise lithiation sites and tunable capacities. The organic functional groups can provide additional benefits, such as discharge voltage and energy efficiency enhancement by phenyl groups and cycling stability improvement by N-heterocycles. Furthermore, replacing sulfur by selenium in these compounds can improve their electrochemical properties due to the high electronic conductivity and low bond energy associated with selenium. We list organosulfide polymers consisting of phenyl rings, N-heterocycles, or aliphatic segments. Organosulfides as electrolyte additives or components for forming a solid-electrolyte interphase layer on lithium metal anode are also presented. Carbon materials such as carbon nanotubes and reduced graphene oxide can enhance the battery performance of organosulfide cathodes. We discuss the synthesis methods for polysulfide molecules and polymers. Finally, we show the advantages of organosulfides over sulfur as cathode materials in lithium batteries. This Account provides a summary of recent development, in-depth analysis of structure-performance relationship, and guidance for future development of organosulfides as promising cathode materials for next generation rechargeable lithium batteries. 10.1021/acs.accounts.9b00231
    Activating Inert Metallic Compounds for High-Rate Lithium-Sulfur Batteries Through In Situ Etching of Extrinsic Metal. Zhao Meng,Peng Hong-Jie,Zhang Ze-Wen,Li Bo-Quan,Chen Xiao,Xie Jin,Chen Xiang,Wei Jun-Yu,Zhang Qiang,Huang Jia-Qi Angewandte Chemie (International ed. in English) Surface reactions constitute the foundation of various energy conversion/storage technologies, such as the lithium-sulfur (Li-S) batteries. To expedite surface reactions for high-rate battery applications demands in-depth understanding of reaction kinetics and rational catalyst design. Now an in situ extrinsic-metal etching strategy is used to activate an inert monometal nitride of hexagonal Ni N through iron-incorporated cubic Ni FeN. In situ etched Ni FeN regulates polysulfide-involving surface reactions at high rates. Electron microscopy was used to unveil the mechanism of in situ catalyst transformation. The Li-S batteries modified with Ni FeN exhibited superb rate capability, remarkable cycling stability at a high sulfur loading of 4.8 mg cm , and lean-electrolyte operability. This work opens up the exploration of multimetallic alloys and compounds as kinetic regulators for high-rate Li-S batteries and also elucidates catalytic surface reactions and the role of defect chemistry. 10.1002/anie.201812062
    Highly Dispersed Catalytic CoS among a Hierarchical Carbon Nanostructure for High-Rate and Long-Life Lithium-Sulfur Batteries. Zhang Hui,Zou Mingchu,Zhao Wenqi,Wang Yunsong,Chen Yijun,Wu Yizeng,Dai Linxiu,Cao Anyuan ACS nano Lithium-sulfur (Li-S) batteries are next-generation energy storage systems with high energy density, and the rate performance is a very important consideration for practical applications. Recent approaches such as introducing catalytic materials to facilitate polysulfide conversion have been explored, yet the results remain unsatisfactory. Here, we present an optimized Li-S electrode featured by a large amount of highly dispersed CoS nanoparticles (∼10 nm in size) throughout a hierarchical carbon nanostructure hybridized from ZIF-67 and carbon nanotube (CNT) sponge. This enables homogeneous distribution and close contact between infiltrated sulfur and CoS nanoparticles within the ZIF-67-derived N-doped carbon nanocubes, leading to effective chemical interaction with polysulfides, maximum catalytic effect and enhanced lithium ion diffusion, while the built-in three-dimensional CNT network ensures high electrical conductivity of the electrode. As a consequence, the Li-S battery exhibits both extraordinary rate performance by maintaining a capacity of ∼850 mAh g at very high charge/discharge rate (5 C) and long-term cycling stability with 85% retention after 1000 cycles at 5 C (an average capacity fading rate of only 0.0137% per cycle). 10.1021/acsnano.8b07843
    Current Status and Future Prospects of Metal-Sulfur Batteries. Chung Sheng-Heng,Manthiram Arumugam Advanced materials (Deerfield Beach, Fla.) Lithium-sulfur batteries are a major focus of academic and industrial energy-storage research due to their high theoretical energy density and the use of low-cost materials. The high energy density results from the conversion mechanism that lithium-sulfur cells utilize. The sulfur cathode, being naturally abundant and environmentally friendly, makes lithium-sulfur batteries a potential next-generation energy-storage technology. The current state of the research indicates that lithium-sulfur cells are now at the point of transitioning from laboratory-scale devices to a more practical energy-storage application. Based on similar electrochemical conversion reactions, the low-cost sulfur cathode can be coupled with a wide range of metallic anodes, such as sodium, potassium, magnesium, calcium, and aluminum. These new "metal-sulfur" systems exhibit great potential in either lowering the production cost or producing high energy density. Inspired by the rapid development of lithium-sulfur batteries and the prospect of metal-sulfur cells, here, over 450 research articles are summarized to analyze the research progress and explore the electrochemical characteristics, cell-assembly parameters, cell-testing conditions, and materials design. In addition to highlighting the current research progress, the possible future areas of research which are needed to bring conversion-type lithium-sulfur and other metal-sulfur batteries into the market are also discussed. 10.1002/adma.201901125
    In situ optical spectroscopy characterization for optimal design of lithium-sulfur batteries. Zhang Li,Qian Tao,Zhu Xingyu,Hu Zhongli,Wang Mengfan,Zhang Liya,Jiang Tao,Tian Jing-Hua,Yan Chenglin Chemical Society reviews The lithium-sulfur (Li-S) battery is one of the most promising high-energy-density secondary battery systems. However, it suffers from issues arising from its extremely complicated "solid-liquid-solid" reaction routes. In recent years, enormous advances have been made in optimizing Li-S batteries via the rational design of compositions and architectures. Nevertheless, a comprehensive and in-depth understanding of the practical reaction mechanisms of Li-S systems and their effect on the electrochemical performance is still lacking. Very recently, several important in situ optical spectroscopic techniques, including Raman, infrared and ultraviolet-visible spectroscopies, have been developed to monitor the real-time variations of the battery states, and a bridge linking the macroscopic electrochemical performance and microscopic architectures of the components has been set up, thus playing a critical role in scientifically guiding further optimal design of Li-S batteries. In this tutorial review, we provide a systematic summary of the state-of-the-art innovations in the characterization and optimal design of Li-S batteries with the aid of these in situ optical spectroscopic techniques, to guide a beginner to construct in situ optical spectroscopy electrochemical cells, and develop strategies for preventing long-chain polysulfide formation, dissolution and migration, thus alleviating the shuttle effect in Li-S batteries and improving the cell performances significantly. 10.1039/c9cs00381a
    3D Honeycomb Architecture Enables a High-Rate and Long-Life Iron (III) Fluoride-Lithium Battery. Wu Feixiang,Srot Vesna,Chen Shuangqiang,Lorger Simon,van Aken Peter A,Maier Joachim,Yu Yan Advanced materials (Deerfield Beach, Fla.) Metal fluoride-lithium batteries with potentially high energy densities, even higher than lithium-sulfur batteries, are viewed as very promising candidates for next-generation lightweight and low-cost rechargeable batteries. However, so far, metal fluoride cathodes have suffered from poor electronic conductivity, sluggish reaction kinetics and side reactions causing high voltage hysteresis, poor rate capability, and rapid capacity degradation upon cycling. Herein, it is reported that an FeF @C composite having a 3D honeycomb architecture synthesized by a simple method may overcome these issues. The FeF nanoparticles (10-50 nm) are uniformly embedded in the 3D honeycomb carbon framework where the honeycomb walls and hexagonal-like channels provide sufficient pathways for the fast electron and Li-ion diffusion, respectively. As a result, the as-produced 3D honeycomb FeF @C composite cathodes even with high areal FeF loadings of 2.2 and 5.3 mg cm offer unprecedented rate capability up to 100 C and remarkable cycle stability within 1000 cycles, displaying capacity retentions of 95%-100% within 200 cycles at various C rates, and ≈85% at 2C within 1000 cycles. The reported results demonstrate that the 3D honeycomb architecture is a powerful composite design for conversion-type metal fluorides to achieve excellent electrochemical performance in metal fluoride-lithium batteries. 10.1002/adma.201905146
    Single Nickel Atoms on Nitrogen-Doped Graphene Enabling Enhanced Kinetics of Lithium-Sulfur Batteries. Zhang Linlin,Liu Daobin,Muhammad Zahir,Wan Fang,Xie Wei,Wang Yijing,Song Li,Niu Zhiqiang,Chen Jun Advanced materials (Deerfield Beach, Fla.) Lithium-sulfur (Li-S) batteries have arousing interest because of their high theoretical energy density. However, they often suffer from sluggish conversion of lithium polysulfides (LiPS) during the charge/discharge process. Single nickel (Ni) atoms on nitrogen-doped graphene (Ni@NG) with Ni-N structure are prepared and introduced to modify the separators of Li-S batteries. The oxidized Ni sites of the Ni-N structure act as polysulfide traps, efficiently accommodating polysulfide ion electrons by forming strong S ⋅⋅⋅NiN bonding. Additionally, charge transfer between the LiPS and oxidized Ni sites endows the LiPS on Ni@NG with low free energy and decomposition energy barrier in an electrochemical process, accelerating the kinetic conversion of LiPS during the charge/discharge process. Furthermore, the large binding energy of LiPS on Ni@NG also shows its ability to immobilize the LiPS and further suppresses the undesirable shuttle effect. Therefore, a Li-S battery based on a Ni@NG modified separator exhibits excellent rate performance and stable cycling life with only 0.06% capacity decay per cycle. It affords fresh insights for developing single-atom catalysts to accelerate the kinetic conversion of LiPS for highly stable Li-S batteries. 10.1002/adma.201903955
    A General Atomic Surface Modification Strategy for Improving Anchoring and Electrocatalysis Behavior of TiCT MXene in Lithium-Sulfur Batteries. Wang Dashuai,Li Fei,Lian Ruqian,Xu Jing,Kan Dongxiao,Liu Yanhui,Chen Gang,Gogotsi Yury,Wei Yingjin ACS nano Multiple negative factors, including the poor electronic conductivity of sulfur, dissolution and shuttling of lithium polysulfides (LiS), and sluggish decomposition of solid LiS, seriously hinder practical applications of lithium-sulfur (Li-S) batteries. To solve these problems, a general strategy was proposed for enhancing the electrochemical performance of Li-S batteries using surface-functionalized TiC MXenes. Functionalized TiCT (T = N, O, F, S, and Cl) showed metallic conductivity, as bare TiC. Among all TiCT investigated, TiCS, TiCO, and TiCN offered moderate adsorption strength, which effectively suppressed LiS dissolution and shuttling. This TiCT exhibited effective electrocatalytic ability for LiS decomposition. The LiS decomposition barrier was significantly decreased from 3.390 eV to ∼0.4 eV using TiCS and TiCO, with fast Li diffusivity. Based on these results, O- and S-terminated TiC were suggested as promising host materials for S cathodes. In addition, appropriate functional group vacancies could further promote anchoring and catalytic abilities of TiCT to boost the electrochemical performance of Li-S batteries. Moreover, the advantages of a TiCT host material could be well retained even at high S loading, suggesting the potential of surface-modified MXene for confining sulfur in Li-S battery cathodes. 10.1021/acsnano.9b03412
    Enhanced Electrochemical Kinetics and Polysulfide Traps of Indium Nitride for Highly Stable Lithium-Sulfur Batteries. Zhang Linlin,Chen Xiang,Wan Fang,Niu Zhiqiang,Wang Yijing,Zhang Qiang,Chen Jun ACS nano Lithium-sulfur (Li-S) batteries are strongly considered as promising energy storage devices due to their high capacity and large theoretical energy density. However, the shuttle of polysulfides and their sluggish kinetic conversion in electrochemical processes seriously reduce the utilization of active sulfur, leading to a rapid capacity fading. Herein we introduced indium nitride (InN) nanowires into Li-S batteries through separator modification. Both the indium cation and electron-rich nitrogen atom of InN served as the polysulfide traps through strong chemical affinity. Meanwhile, the rapid electron transfer on the surface of InN accelerated the conversion of polysulfides in a working battery. The bifunction of InN nanowires effectively suppressed the shuttle effect. Therefore, Li-S batteries with InN-modified separators exhibit excellent rate performance and high stable cycling life with only 0.015% capacity decay per cycle after 1000 cycles, which affords fresh insights into the energy chemistry of high-stable Li-S batteries. 10.1021/acsnano.8b05466
    A Selection Rule for Hydrofluoroether Electrolyte Cosolvent: Establishing a Linear Free-Energy Relationship in Lithium-Sulfur Batteries. Su Chi-Cheung,He Meinan,Amine Rachid,Amine Khalil Angewandte Chemie (International ed. in English) Hydrofluoroethers (HFEs) have been adopted widely as electrolyte cosolvents for battery systems because of their unique low solvating behavior. The electrolyte is currently utilized in lithium-ion, lithium-sulfur, lithium-air, and sodium-ion batteries. By evaluating the relative solvating power of different HFEs with distinct structural features, and considering the shuttle factor displayed by electrolytes that employ HFE cosolvents, we have established the quantitative structure-activity relationship between the organic structure and the electrochemical performance of the HFEs. Moreover, we have established the linear free-energy relationship between the structural properties of the electrolyte cosolvents and the polysulfide shuttle effect in lithium-sulfur batteries. These findings provide valuable mechanistic insight into the polysulfide shuttle effect in lithium-sulfur batteries, and are instructive when it comes to selecting the most suitable HFE electrolyte cosolvent for different battery systems. 10.1002/anie.201904240
    Developing A "Polysulfide-Phobic" Strategy to Restrain Shuttle Effect in Lithium-Sulfur Batteries. He Yibo,Qiao Yu,Chang Zhi,Cao Xin,Jia Min,He Ping,Zhou Haoshen Angewandte Chemie (International ed. in English) Inspired by hydrophobic interface, a novel design of "polysulfide-phobic" interface was proposed and developed to restrain shuttle effect in lithium-sulfur batteries. Two-dimensional VOPO sheets with adequate active sites were employed to immobilize the polysulfides through the formation of a V-S bond. Moreover, owing to the intrinsic Coulomb repulsion between polysulfide anions, the surface anchored with polysulfides can be further evolved into a "polysulfide-phobic" interface, which was demonstrated by the advanced time/space-resolved operando Raman evidences. In particular, by introducing the "polysulfide-phobic" surface design into separator fabrication, the lithium-sulfur battery performed a superior long-term cycling stability. This work expands a novel strategy to build a "polysulfide-phobic" surface by "self-defense" mechanism for suppressing polysulfides shuttle, which provides new insights and opportunities to develop advanced lithium-sulfur batteries. 10.1002/anie.201906055
    The Relationship between the Relative Solvating Power of Electrolytes and Shuttling Effect of Lithium Polysulfides in Lithium-Sulfur Batteries. Su Chi-Cheung,He Meinan,Amine Rachid,Chen Zonghai,Amine Khalil Angewandte Chemie (International ed. in English) Relative solvating power, that is, the ratio of the coordination ratios between a solvent and the reference solvent, was used to probe the quantitative structure-activity relationship of electrolyte solvents and the lithium polysulfide (LiPS) dissolution in lithium-sulfur batteries. Internally referenced diffusion-ordered nuclear magnetic resonance spectroscopy (IR-DOSY) was used to determine the diffusion coefficient and coordination ratio, from which the relative solvating power can be easily measured. The higher the relative solvating power of an ethereal solvent, the more severe will be the LiPS dissolution and the lower the coulombic efficiency of the lithium-sulfur battery. A linear relationship was established between the logarithm of relative solvating power of a solvent and the degree of LiPS dissolution, rendering relative solvating power an important parameter in choosing the electrolyte solvent for lithium-sulfur batteries. 10.1002/anie.201807367
    Interfacial Mechanism in Lithium-Sulfur Batteries: How Salts Mediate the Structure Evolution and Dynamics. Lang Shuang-Yan,Xiao Rui-Juan,Gu Lin,Guo Yu-Guo,Wen Rui,Wan Li-Jun Journal of the American Chemical Society Lithium-sulfur batteries possess favorable potential for energy-storage applications because of their high specific capacity and the low cost of sulfur. Intensive understanding of the interfacial mechanism, especially the polysulfide formation and transformation under complex electrochemical environment, is crucial for the buildup of advanced batteries. Here, we report the direct visualization of interfacial evolution and dynamic transformation of the sulfides mediated by the lithium salts via real-time atomic force microscopy monitoring inside a working battery. The observations indicate that the lithium salts influence the structures and processes of sulfide deposition/decomposition during discharge/charge. Moreover, the distinct ion interaction and the diffusion in electrolytes manipulate the interfacial reactions determining the kinetics of the sulfide transformation. Our findings provide deep insights into surface dynamics of lithium-sulfur reactions revealing the salt-mediated mechanisms at nanoscale, which contribute to the profound understanding of the interfacial processes for the optimized design of lithium-sulfur batteries. 10.1021/jacs.8b02057
    In Situ Self-Formed Nanosheet MoS/Reduced Graphene Oxide Material Showing Superior Performance as a Lithium-Ion Battery Cathode. Chang Uijin,Lee Jung Tae,Yun Jin-Mun,Lee Byeongyoung,Lee Seung Woo,Joh Han-Ik,Eom KwangSup,Fuller Thomas F ACS nano Although lithium-sulfur (Li-S) batteries have 5-10 times higher theoretical capacity (1675 mAh g) than present commercial lithium-ion batteries, Li-S batteries show a rapid and continuous capacity fading due to the polysulfide dissolution in common electrolytes. Here, we propose the use of a sulfur-based cathode material, amorphous MoS and reduced graphene oxide (r-GO) composite, which can be substituted for the pure sulfur-based cathodes. In order to enhance kinetics and stability of the electrodes, we intentionally pulverize the microsized MoS sheet into nanosheets and form an ultrathin nano-SEI on the surface using in situ electrochemical methods. Then, the pulverized nanosheets are securely anchored by the oxygen functional group of r-GO. As a result, the electrochemically treated MoS/r-GO electrode shows superior performance that surpasses pure sulfur-based electrodes; it exhibits a capacity of about 900 mAh g at a rate of 5C for 2500 cycles without capacity fading. Moreover, a full-cell battery employing the MoS/r-GO cathode with a silicon-carbon composite anode displays a 3-5 times higher energy density (1725 Wh kg/7100 Wh L) than present LIBs. 10.1021/acsnano.8b07191
    A 3D Nitrogen-Doped Graphene/TiN Nanowires Composite as a Strong Polysulfide Anchor for Lithium-Sulfur Batteries with Enhanced Rate Performance and High Areal Capacity. Li Zhaohuai,He Qiu,Xu Xu,Zhao Yan,Liu Xiaowei,Zhou Cheng,Ai Dong,Xia Lixue,Mai Liqiang Advanced materials (Deerfield Beach, Fla.) Lithium-sulfur (Li-S) batteries have attracted remarkable attention due to their high theoretical capacity of 1675 mAh g , rich resources, inexpensiveness, and environmental friendliness. However, the practical application of the Li-S battery is hindered by the shuttling of soluble lithium polysulfides (LiPSs) and slow redox reactions. Herein, a 3D nitrogen-doped graphene/titanium nitride nanowires (3DNG/TiN) composite is reported as a freestanding electrode for Li-S batteries. The highly porous conductive graphene network provides efficient pathways for both electrons and ions. TiN nanowires attached on the graphene sheets have a strong chemical anchor effect on the polysulfides, which is proved by the superior performance and by density functional theory calculations. As a result, the 3DNG/TiN cathode exhibits an initial capacity of 1510 mAh g and the capacity remains at 1267 mAh g after 100 cycles at 0.5 C. Even at 5 C, a capacity of 676 mAh g is reached. With a high sulfur loading of 9.6 mg cm , the 3DNG cathode achieves an ultrahigh areal capacity of 12.0 mAh cm at a high current density of 8.03 mA cm . This proposed unique structure gives a bright prospect in that high energy density and high power density can be achieved simultaneously for Li-S batteries. 10.1002/adma.201804089
    Lithium-Sulfur Batteries under Lean Electrolyte Conditions: Challenges and Opportunities. Zhao Meng,Li Bo-Quan,Peng Hong-Jie,Yuan Hong,Wei Jun-Yu,Huang Jia-Qi Angewandte Chemie (International ed. in English) The development of energy-storage devices has received increasing attention as a transformative technology to realize a low-carbon economy and sustainable energy supply. Lithium-sulfur (Li-S) batteries are considered to be one of the most promising next-generation energy-storage devices due to their ultrahigh energy density. Despite the extraordinary progress in the last few years, the actual energy density of Li-S batteries is still far from satisfactory to meet the demand for practical applications. Considering the sulfur electrochemistry is highly dependent on solid-liquid-solid multi-phase conversion, the electrolyte amount plays a primary role in the practical performances of Li-S cells. Therefore, a lean electrolyte volume with low electrolyte/sulfur ratio is essential for practical Li-S batteries, yet under these conditions it is highly challenging to achieve acceptable electrochemical performances regarding sulfur kinetics, discharge capacity, Coulombic efficiency, and cycling stability especially for high-sulfur-loading cathodes. In this Review, the impact of the electrolyte/sulfur ratio on the actual energy density and the economic cost of Li-S batteries is addressed. Challenges and recent progress are presented in terms of the sulfur electrochemical processes: the dissolution-precipitation conversion and the solid-solid multi-phasic transition. Finally, prospects of future lean-electrolyte Li-S battery design and engineering are discussed. 10.1002/anie.201909339
    Suppression of Polysulfide Dissolution and Shuttling with Glutamate Electrolyte for Lithium Sulfur Batteries. Dong Liwei,Liu Jipeng,Chen Dongjiang,Han Yupei,Liang Yifang,Yang Mengqiu,Yang Chunhui,He Weidong ACS nano The lithium sulfur battery is regarded as a potential next-generation high-energy battery system. However, polysulfides dissolve and shuttle through the electrolytes, causing rapid capacity decay, serious self-discharge, and poor high-temperature performances. Here, we demonstrate that by directly introducing glutamate into commercial electrolytes, these issues can be tackled simultaneously. With abundant negatively charged hydroxyl groups, the glutamate additive electrolyte effectively suppresses the shuttling of negatively charged polysulfide ions through strong repulsive interaction up to 1.54 eV. With glutamate additive electrolyte, the lithium sulfur battery has a capacity retention of 60% after 1000 cycles at 5.95 mA/cm, a self-discharge rate on the order of one-third that of commercial electrolytes, and stable operation at 60 °C. 10.1021/acsnano.9b06934
    The Regulating Role of Carbon Nanotubes and Graphene in Lithium-Ion and Lithium-Sulfur Batteries. Fang Ruopian,Chen Ke,Yin Lichang,Sun Zhenhua,Li Feng,Cheng Hui-Ming Advanced materials (Deerfield Beach, Fla.) The ever-increasing demands for batteries with high energy densities to power the portable electronics with increased power consumption and to advance vehicle electrification and grid energy storage have propelled lithium battery technology to a position of tremendous importance. Carbon nanotubes (CNTs) and graphene, known with many appealing properties, are investigated intensely for improving the performance of lithium-ion (Li-ion) and lithium-sulfur (Li-S) batteries. However, a general and objective understanding of their actual role in Li-ion and Li-S batteries is lacking. It is recognized that CNTs and graphene are not appropriate active lithium storage materials, but are more like a regulator: they do not electrochemically react with lithium ions and electrons, but serve to regulate the lithium storage behavior of a specific electroactive material and increase the range of applications of a lithium battery. First, metrics for the evaluation of lithium batteries are discussed, based on which the regulating role of CNTs and graphene in Li-ion and Li-S batteries is comprehensively considered from fundamental electrochemical reactions to electrode structure and integral cell design. Finally, perspectives on how CNTs and graphene can further contribute to the development of lithium batteries are presented. 10.1002/adma.201800863
    Mechanistic Understanding of Metal Phosphide Host for Sulfur Cathode in High-Energy-Density Lithium-Sulfur Batteries. Shen Jiadong,Xu Xijun,Liu Jun,Liu Zhengbo,Li Fangkun,Hu Renzong,Liu Jiangwen,Hou Xianhua,Feng Yuezhan,Yu Yan,Zhu Min ACS nano For solving the drawbacks of low conductivity and the shuttle effect in a sulfur cathode, various nonpolar carbon and polar metal compounds with strong chemical absorption ability are applied as sulfur host materials for lithium-sulfur (Li-S) batteries. Nevertheless, previous research simply attributed the performance improvement of sulfur cathodes to the chemical adsorption ability of polar metal compounds toward lithium polysulfides (LPS), while a deep understanding of the enhanced electrochemical performance in these various sulfur hosts, especially at the molecular levels, is still unclear. Herein, for a mechanistic understanding of superior metal phosphide host in Li-S battery chemistry, an integrated phosphide-based host of CF/FeP@C (carbon cloth with grown FeP@C nanotube arrays) is chosen as the model, and this binder-free cathode can exclude interference from the binder and conductive additives. With a systematic electrochemical investigation of the loading sulfur in such oxide- and phosphide-based hosts (CF/FeO@C and CF/FeP@C), it is found that CF/FeP@C@S shows much superior Li-S performances. The greatly enhanced performance of CF/FeP@C@S suggests that FeP can well suppress the shuttle effect of LPS and accelerate their transformation during the charge-discharge process. The first-principles calculations reveal the performance variations of FeO and FeP in Li-S batteries mainly because the shifts of the p band of the FeP could accelerate the interfacial electronics transfer dynamics by increasing the electronic concentration in the Fermi level of adsorbed LiS. The current work sheds light on the promising design of superior Li-S batteries from both theoretical and experimental aspects. 10.1021/acsnano.9b02903
    Redox Catalytic and Quasi-Solid Sulfur Conversion for High-Capacity Lean Lithium Sulfur Batteries. Lu Ke,Liu Yuzi,Chen Junzheng,Zhang Zhengcheng,Cheng Yingwen ACS nano The practical deployment of lithium sulfur batteries demands stable cycling of high loading and dense sulfur cathodes under lean electrolyte conditions, which is very difficult to realize. We describe here a strategy of fabricating extremely dense sulfur cathodes, designed by integrating MoS nanoparticles as a multifunctional mediator with a Li-ion conducting binder and a high-performance FeO@N-carbon sulfur host. The MoS nanoparticles have substantially faster Li-ion insertion kinetics compared with sulfur, and the produced LiMoS particles have spontaneous redox reactivity with relevant polysulfide species (such as LiMoS + LiS ↔ LiMoS + LiS, Δ = -84 kJ mol), which deliver a true redox catalytic sulfur conversion mechanism. In addition, LiMoS particles strongly absorb polysulfide during battery cycling, which provides a quasi-solid sulfur conversion pathway and almost eliminated polysulfide dissolution. Such a pathway not only promotes growth of uniform LiS that can be readily charged back with nearly no overpotential, but also mitigates the polysulfide-induced Li metal corrosion issue. The combination of these benefits enables stable and high capacity cycling of dense sulfur cathodes under a low electrolyte to sulfur ratio (4.2 μL mg), as demonstrated with cathodes with volumetric capacities of at least 1.3 Ah cm and capacity retentions of ∼80% for 300 cycles. Furthermore, stable cycling of batteries under a practically relevant N/P ratio of 2.4 is also demonstrated. 10.1021/acsnano.9b08516
    Surface-Modified Sulfur Nanorods Immobilized on Radially Assembled Open-Porous Graphene Microspheres for Lithium-Sulfur Batteries. Yeon Jeong Seok,Yun Sol,Park Jae Min,Park Ho Seok ACS nano The assembly of two-dimensional conductive nanomaterials into hierarchical complex architectures precisely controlling internal open porosity and orientation, external morphology, composition, and interaction is expected to provide promising hosts for high-capacity sulfur cathodes. Herein, we demonstrate rod-like nanosulfur (nS) deposited onto radially oriented open-porous microspherical reduced graphene oxide (rGO) architectures for improved rate and cyclic capabilities of lithium-sulfur (Li-S) batteries. The combined chemistry of a spray-frozen assembly and ozonation drives the formation of a radially oriented open-porous structure and an overall microspherical morphology as well as uniform distribution and high loading of rod-like nS. Moreover, an optimum composition and strong bonding of the rGO/nS hybrid enables the optimization of redox kinetics for high sulfur utilization and high-rate capacities. The resulting rGO/nS hybrid provides a specific capacity and first-cycle Coulombic efficiency of 1269.1 mAh g and 98.5%, respectively, which are much greater than those of ice-templated and physically mixed rGO/nS hybrids and radially oriented open-porous rGO/bulk sulfur with the same hybrid composition. A 4C capacity of 510.3 mAhg and capacity decay of 0.08% per cycle over 500 cycles (70.9% of the initial capacity over 300 cycles) also support the synergistic effect of the rod-like nS strongly interacting with the radially oriented open-porous rGO microspheres. 10.1021/acsnano.8b08822
    Achieving three-dimensional lithium sulfide growth in lithium-sulfur batteries using high-donor-number anions. Chu Hyunwon,Noh Hyungjun,Kim Yun-Jung,Yuk Seongmin,Lee Ju-Hyuk,Lee Jinhong,Kwack Hobeom,Kim YunKyoung,Yang Doo-Kyung,Kim Hee-Tak Nature communications Uncontrolled growth of insulating lithium sulfide leads to passivation of sulfur cathodes, which limits high sulfur utilization in lithium-sulfur batteries. Sulfur utilization can be augmented in electrolytes based on solvents with high Gutmann Donor Number; however, violent lithium metal corrosion is a drawback. Here we report that particulate lithium sulfide growth can be achieved using a salt anion with a high donor number, such as bromide or triflate. The use of bromide leads to ~95 % sulfur utilization by suppressing electrode passivation. More importantly, the electrolytes with high-donor-number salt anions are notably compatible with lithium metal electrodes. The approach enables a high sulfur-loaded cell with areal capacity higher than 4 mA h cm and high sulfur utilization ( > 90 %). This work offers a simple but practical strategy to modulate lithium sulfide growth, while conserving stability for high-performance lithium-sulfur batteries. 10.1038/s41467-018-07975-4
    Lithium Silicide Surface Enrichment: A Solution to Lithium Metal Battery. Tang Wei,Yin Xuesong,Kang Sujin,Chen Zhongxin,Tian Bingbing,Teo Siew Lang,Wang Xiaowei,Chi Xiao,Loh Kian Ping,Lee Hyun-Wook,Zheng Guangyuan Wesley Advanced materials (Deerfield Beach, Fla.) The propensity of lithium dendrite formation during the charging process of lithium metal batteries is linked to inhomogeneity on the lithium surface layer. The high reactivity of lithium and the complex surface structure of the native layer create "hot spots" for fast dendritic growth. Here, it is demonstrated that a fundamental restructuring of the lithium surface in the form of lithium silicide (Li Si) can effectively eliminate the surface inhomogeneity on the lithium surface. In situ optical microscopic study is carried out to monitor the electrochemical deposition of lithium on the Li Si-modified lithium electrodes and the bare lithium electrode. It is observed that a much more uniform lithium dissolution/deposition on the Li Si-modified lithium anode can be achieved as compared to the bare lithium electrode. Full cells paring the modified lithium anode with sulfur and LiFePO cathodes show excellent electrochemical performances in terms of rate capability and cycle stability. Compatibility of the anode enrichment method with mass production process also offers a practical way for enabling lithium metal anode for next-generation lithium batteries. 10.1002/adma.201801745
    A Sulfur-Limonene-Based Electrode for Lithium-Sulfur Batteries: High-Performance by Self-Protection. Wu Feixiang,Chen Shuangqiang,Srot Vesna,Huang Yuanye,Sinha Shyam Kanta,van Aken Peter A,Maier Joachim,Yu Yan Advanced materials (Deerfield Beach, Fla.) The lithium-sulfur battery is considered as one of the most promising energy storage systems and has received enormous attentions due to its high energy density and low cost. However, polysulfide dissolution and the resulting shuttle effects hinder its practical application unless very costly solutions are considered. Herein, a sulfur-rich polymer termed sulfur-limonene polysulfide is proposed as powerful electroactive material that uniquely combines decisive advantages and leads out of this dilemma. It is amenable to a large-scale synthesis by the abundant, inexpensive, and environmentally benign raw materials sulfur and limonene (from orange and lemon peels). Moreover, owing to self-protection and confinement of lithium sulfide and sulfur, detrimental dissolution and shuttle effects are successfully avoided. The sulfur-limonene-based electrodes (without elaborate synthesis or surface modification) exhibit excellent electrochemical performances characterized by high discharge capacities (≈1000 mA h g at C/2) and remarkable cycle stability (average fading rate as low as 0.008% per cycle during 300 cycles). 10.1002/adma.201706643
    Chemisorption of polysulfides through redox reactions with organic molecules for lithium-sulfur batteries. Li Ge,Wang Xiaolei,Seo Min Ho,Li Matthew,Ma Lu,Yuan Yifei,Wu Tianpin,Yu Aiping,Wang Shun,Lu Jun,Chen Zhongwei Nature communications Lithium-sulfur battery possesses high energy density but suffers from severe capacity fading due to the dissolution of lithium polysulfides. Novel design and mechanisms to encapsulate lithium polysulfides are greatly desired by high-performance lithium-sulfur batteries towards practical applications. Herein, we report a strategy of utilizing anthraquinone, a natural abundant organic molecule, to suppress dissolution and diffusion of polysulfides species through redox reactions during cycling. The keto groups of anthraquinone play a critical role in forming strong Lewis acid-based chemical bonding. This mechanism leads to a long cycling stability of sulfur-based electrodes. With a high sulfur content of ~73%, a low capacity decay of 0.019% per cycle for 300 cycles and retention of 81.7% over 500 cycles at 0.5 C rate can be achieved. This finding and understanding paves an alternative avenue for the future design of sulfur-based cathodes toward the practical application of lithium-sulfur batteries. 10.1038/s41467-018-03116-z
    Confined Lithium-Sulfur Reactions in Narrow-Diameter Carbon Nanotubes Reveal Enhanced Electrochemical Reactivity. Fu Chengyin,Oviedo M Belén,Zhu Yihan,von Wald Cresce Arthur,Xu Kang,Li Guanghui,Itkis Mikhail E,Haddon Robert C,Chi Miaofang,Han Yu,Wong Bryan M,Guo Juchen ACS nano We demonstrate an unusual electrochemical reaction of sulfur with lithium upon encapsulation in narrow-diameter (subnanometer) single-walled carbon nanotubes (SWNTs). Our study provides mechanistic insight on the synergistic effects of sulfur confinement and Li ion solvation properties that culminate in a new mechanism of these sub-nanoscale-enabled reactions (which cannot be solely attributed to the lithiation-delithiation of conventional sulfur). Two types of SWNTs with distinct diameters, produced by electric arc (EA-SWNTs, average diameter 1.55 nm) or high-pressure carbon monoxide (HiPco-SWNTs, average diameter 1.0 nm), are investigated with two comparable electrolyte systems based on tetraethylene glycol dimethyl ether (TEGDME) and 1,4,7,10,13-pentaoxacyclopentadecane (15-crown-5). Electrochemical analyses indicate that a conventional solution-phase Li-S reaction occurs in EA-SWNTs, which can be attributed to the smaller solvated [Li(TEGDME)] and [Li(15-crown-5)] ions within the EA-SWNT diameter. In stark contrast, the Li-S confined in narrower diameter HiPco-SWNTs exhibits unusual electrochemical behavior that can be attributed to a solid-state reaction enabled by the smaller HiPco-SWNT diameter compared to the size of solvated Li ions. Our results of the electrochemical analyses are corroborated and supported with various spectroscopic analyses including operando Raman, X-ray photoelectron spectroscopy, and first-principles calculations from density functional theory. Taken together, our findings demonstrate that the controlled solid-state lithiation-delithiation of sulfur and an enhanced electrochemical reactivity can be achieved by sub-nanoscale encapsulation and one-dimensional confinement in narrow-diameter SWNTs. 10.1021/acsnano.7b08778
    An Intrinsic Flame-Retardant Organic Electrolyte for Safe Lithium-Sulfur Batteries. Yang Huijun,Guo Cheng,Chen Jiahang,Naveed Ahmad,Yang Jun,Nuli Yanna,Wang Jiulin Angewandte Chemie (International ed. in English) Safety concerns pose a significant challenge for the large-scale employment of lithium-sulfur batteries. Extremely flammable conventional electrolytes and dendritic lithium deposition cause severe safety issues. Now, an intrinsic flame-retardant (IFR) electrolyte is presented consisting of 1.1 m lithium bis(fluorosulfonyl)imide in a solvent mixture of flame-retardant triethyl phosphate and high flashpoint solvent 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl (1:3, v/v) for safe lithium-sulfur (Li-S) batteries. This electrolyte exhibits favorable flame-retardant properties and high reversibility of the lithium metal anode (Coulombic efficiency >99 %). This IFR electrolyte enables stable lithium plating/stripping behavior with micro-sized and dense-packing lithium deposition at high temperatures. When coupled with a sulfurized pyrolyzed poly(acrylonitrile) cathode, Li-S batteries deliver a high composite capacity (840.1 mAh g ) and high sulfur utilization of 95.6 %. 10.1002/anie.201811291
    Full Dissolution of the Whole Lithium Sulfide Family (Li S to Li S) in a Safe Eutectic Solvent for Rechargeable Lithium-Sulfur Batteries. Cheng Qian,Xu Weiheng,Qin Shiyi,Das Subhabrata,Jin Tianwei,Li Aijun,Li Alex Ceng,Qie Boyu,Yao Pengcheng,Zhai Haowei,Shi Changmin,Yong Xin,Yang Yuan Angewandte Chemie (International ed. in English) The lithium-sulfur battery is an attractive option for next-generation energy storage owing to its much higher theoretical energy density than state-of-the-art lithium-ion batteries. However, the massive volume changes of the sulfur cathode and the uncontrollable deposition of Li S /Li S significantly deteriorate cycling life and increase voltage polarization. To address these challenges, we develop an ϵ-caprolactam/acetamide based eutectic-solvent electrolyte, which can dissolve all lithium polysulfides and lithium sulfide (Li S -Li S). With this new electrolyte, high specific capacity (1360 mAh g ) and reasonable cycling stability are achieved. Moreover, in contrast to conventional ether electrolyte with a low flash point (ca. 2 °C), such low-cost eutectic-solvent-based electrolyte is difficult to ignite, and thus can dramatically enhance battery safety. This research provides a new approach to improving lithium-sulfur batteries in aspects of both safety and performance. 10.1002/anie.201812611
    Low-Bandgap Se-Deficient Antimony Selenide as a Multifunctional Polysulfide Barrier toward High-Performance Lithium-Sulfur Batteries. Tian Yuan,Li Gaoran,Zhang Yongguang,Luo Dan,Wang Xin,Zhao Yan,Liu Hui,Ji Puguang,Du Xiaohang,Li Jingde,Chen Zhongwei Advanced materials (Deerfield Beach, Fla.) The shuttling behavior and sluggish conversion kinetics of the intermediate lithium polysulfides (LiPSs) represent the main obstructions to the practical application of lithium-sulfur (Li-S) batteries. Herein, an anion-deficient design of antimony selenide (Sb Se ) is developed to establish a multifunctional LiPS barrier toward the inhibition of polysulfide shuttling and enhancement of battery performance. The defect chemistry in the as-developed Sb Se promotes the intrinsic conductivity, strengthens the chemical affinity to LiPSs, and catalyzes the sulfur electrochemical conversion, which are verified by a series of computational and experimental results. Attributed to these unique superiorities, the obtained LiPS barrier efficiently promotes and stabilizes the sulfur electrochemistry, thus enabling excellent Li-S battery performance, e.g., outstanding cyclability over 500 cycles at 1.0 C with a minimum capacity fading rate of 0.027% per cycle, a superb rate capability up to 8.0 C, and a high areal capacity of 7.46 mAh cm under raised sulfur loading. This work offers a defect engineering strategy toward fast and durable sulfur electrochemistry, holding great promise in developing practically viable Li-S batteries as well as enlightening the material design of related energy storage and conversion systems. 10.1002/adma.201904876
    Rational design of spontaneous reactions for protecting porous lithium electrodes in lithium-sulfur batteries. Ren Y X,Zeng L,Jiang H R,Ruan W Q,Chen Q,Zhao T S Nature communications A rechargeable lithium anode requires a porous structure for a high capacity, and a stable electrode/electrolyte interface against dendrite formation and polysulfide crossover when used in a lithium-sulfur battery. Here, we design two simple steps of spontaneous reactions for protecting porous lithium electrodes. First, a reaction between molten lithium and sulfur-impregnated carbon nanofiber forms a fibrous network with a lithium shell and a carbon core. Second, we coat the surface of this porous lithium electrode with a composite of lithium bismuth alloys and lithium fluoride through another spontaneous reaction between lithium and bismuth trifluoride, solvated with phosphorous pentasulfide, which also polymerizes with lithium sulfide residual in the electrode to form a solid electrolyte layer. This protected porous lithium electrode enables stable operation of a lithium-sulfur battery with a sulfur loading of 10.2 mg cm at 6.0 mA cm for 200 cycles. 10.1038/s41467-019-11168-y
    A Class of Catalysts of BiOX (X = Cl, Br, I) for Anchoring Polysulfides and Accelerating Redox Reaction in Lithium Sulfur Batteries. Wu Xian,Liu Nannan,Wang Maoxu,Qiu Yue,Guan Bin,Tian Da,Guo Zhikun,Fan Lishuang,Zhang Naiqing ACS nano The lithium-sulfur battery system contains a complex reaction process of sulfur involving multielectron reactions and phase conversions. Moreover, the diffusion of intermediate polysulfides during reduction and sluggish kinetic conversion of polysulfides into insoluble LiS still plague the use of Li-S batteries. Herein, BiOX was employed as sulfur host material in Li-S batteries, which could integrate suppression of the shuttle effect and promote kinetics redox reactions of lithium polysulfides. The polar BiOX displays a robust chemical adsorption ability with polysulfides, and the electrocatalytic activity of BiOX would accelerate the fragmentation of polysulfides into shorter chains. The results indicate that the good polysulfide reactivity not only ensures the effective reduction of polarization but also performs high discharge capacity and stable cycle performance. The battery with a BiOCl/G-S cathode reveals a high capacity of 1414 mA h/g at a current of 0.1 C and a low capacity decay rate of 0.007% during 2000 cycles at a current of 2 C. This work proposes the prospect of application of the BiOX materials in lithium sulfur batteries. 10.1021/acsnano.9b05908
    Multifunctional Sandwich-Structured Electrolyte for High-Performance Lithium-Sulfur Batteries. Qu Hongtao,Zhang Jianjun,Du Aobing,Chen Bingbing,Chai Jingchao,Xue Nan,Wang Longlong,Qiao Lixin,Wang Chen,Zang Xiao,Yang Jinfeng,Wang Xiaogang,Cui Guanglei Advanced science (Weinheim, Baden-Wurttemberg, Germany) Due to its high theoretical energy density (2600 Wh kg), low cost, and environmental benignity, the lithium-sulfur (Li-S) battery is attracting strong interest among the various electrochemical energy storage systems. However, its practical application is seriously hampered by the so-called shuttle effect of the highly soluble polysulfides. Herein, a novel design of multifunctional sandwich-structured polymer electrolyte (polymer/cellulose nonwoven/nanocarbon) for high-performance Li-S batteries is demonstrated. It is verified that Li-S battery with this sandwich-structured polymer electrolyte delivers excellent cycling stability (only 0.039% capacity decay cycle on average exceeding 1500 cycles at 0.5 C) and rate capability (with a reversible capacity of 594 mA h g at 4 C). These electrochemical performances are attributed to the synergistic effect of each layer in this unique sandwich-structured polymer electrolyte including steady lithium stripping/plating, strong polysulfide absorption ability, and increased redox reaction sites. More importantly, even with high sulfur loading of 4.9 mg cm, Li-S battery with this sandwich-structured polymer electrolyte can deliver high initial areal capacity of 5.1 mA h cm. This demonstrated strategy here may open up a new era of designing hierarchical structured polymer electrolytes for high-performance Li-S batteries. 10.1002/advs.201700503
    A Cathode-Integrated Sulfur-Deficient CoS Catalytic Interlayer for the Reutilization of "Lost" Polysulfides in Lithium-Sulfur Batteries. Lin Haibin,Zhang Shengliang,Zhang Tianran,Cao Sheng,Ye Hualin,Yao Qiaofeng,Zheng Guangyuan Wesley,Lee Jim Yang ACS nano Lithium-sulfur batteries, with their high theoretical energy density and the low material cost of sulfur, are highly promising as a post-lithium ion battery contender. Their current performance is however compromised by sulfur loss and polysulfide shuttle to result in low energy efficiency and poor cycle stability. Herein, a catalytic material (CoS/CNT, nanoparticles with a metallic CoS core and a sulfur-deficient shell on a CNT support) was applied as an interlayer on the sulfur cathode to retain migratory polysulfides and promote their reutilization. The CoS/CNT catalyst is highly effective for the conversion of polysulfides to insoluble end products (S or LiS/LiS), and its deployment as a cathode-integrated interlayer was able to retain the polysulfides in the cathode for reuse. The accumulation of polysulfides in the electrolyte and the polysulfide shuttle were significantly reduced as a result. Consequently, a host-free sulfur cathode with the CoS/CNT interlayer had a low capacity fade rate of 0.049% per cycle for 1000 cycles at a 0.3C rate, a significant improvement of the capacity fade rate without it (0.28% per cycle for 200 cycles). The results here provide not only direct evidence for the contributions of sulfur deficiencies on the catalytic activity of CoS in polysulfide conversion reactions but also the methodology on how the catalyst should be deployed in a Li-S battery for the best catalytic outcome. 10.1021/acsnano.9b02374
    Flexible and stable high-energy lithium-sulfur full batteries with only 100% oversized lithium. Chang Jian,Shang Jian,Sun Yongming,Ono Luis K,Wang Dongrui,Ma Zhijun,Huang Qiyao,Chen Dongdong,Liu Guoqiang,Cui Yi,Qi Yabing,Zheng Zijian Nature communications Lightweight and flexible energy storage devices are urgently needed to persistently power wearable devices, and lithium-sulfur batteries are promising technologies due to their low mass densities and high theoretical capacities. Here we report a flexible and high-energy lithium-sulfur full battery device with only 100% oversized lithium, enabled by rationally designed copper-coated and nickel-coated carbon fabrics as excellent hosts for lithium and sulfur, respectively. These metallic carbon fabrics endow mechanical flexibility, reduce local current density of the electrodes, and, more importantly, significantly stabilize the electrode materials to reach remarkable Coulombic efficiency of >99.89% for a lithium anode and >99.82% for a sulfur cathode over 400 half-cell charge-discharge cycles. Consequently, the assembled lithium-sulfur full battery provides high areal capacity (3 mA h cm), high cell energy density (288 W h kg and 360 W h L), excellent cycling stability (260 cycles), and remarkable bending stability at a small radius of curvature (<1 mm). 10.1038/s41467-018-06879-7
    Self-Formed Hybrid Interphase Layer on Lithium Metal for High-Performance Lithium-Sulfur Batteries. Li Guoxing,Huang Qingquan,He Xin,Gao Yue,Wang Daiwei,Kim Seong H,Wang Donghai ACS nano Lithium-sulfur (Li-S) batteries are promising candidates for high-energy storage devices due to high theoretical capacities of both the sulfur cathode and lithium (Li) metal anode. Considerable efforts have been devoted to improving sulfur cathodes. However, issues associated with Li anodes, such as low Coulombic efficiency (CE) and growth of Li dendrites, remain unsolved due to unstable solid-electrolyte interphase (SEI) and lead to poor capacity retention and a short cycling life of Li-S batteries. In this work, we demonstrate a facile and effective approach to fabricate a flexible and robust hybrid SEI layer through co-deposition of aromatic-based organosulfides and inorganic Li salts using poly(sulfur-random-1,3-diisopropenylbenzene) as an additive in an electrolyte. The aromatic-based organic components with planar backbone conformation and π-π interaction in the SEI layers can improve the toughness and flexibility to promote stable and high efficient Li deposition/dissolution. The as-formed durable SEI layer can inhibit dendritic Li growth, enhance Li deposition/dissolution CE (99.1% over 420 cycles), and in turn enable Li-S batteries with good cycling stability (1000 cycles) and slow capacity decay. This work demonstrates a route to address the issues associated with Li metal anodes and promote the development of high-energy rechargeable Li metal batteries. 10.1021/acsnano.7b08035
    Blocking Polysulfide with CoB@CNT via "Synergetic Adsorptive Effect" toward Ultrahigh-Rate Capability and Robust Lithium-Sulfur Battery. Guan Bin,Zhang Yu,Fan Lishuang,Wu Xian,Wang Maoxu,Qiu Yue,Zhang Naiqing,Sun Kening ACS nano Li-S batteries have attracted great interest as the next-generation secondary batteries due to their high energy density, being environmentally friendly, and low price. However, the road to commercialization of lithium-sulfur batteries remains limited owing to the "shuttle effect" of soluble polysulfides, which results in the inferior cycle stability. Herein, a potent functional separator is developed to restrain the "shuttle effect" by coating CoB@carbon nanotube layer on the commercialized polypropylene separator. In merits of the coadsorption of Co sites and B sites, such CoB shows highly efficient polysulfides block (11.67 mg/m for LiS). Besides, the composite also exhibits obviously catalysis from LiS to LiS. By combining the fast electron transportation along the carbon nanotube, a superior rate performance is achieved with the modified separator and common carbon-sulfur cathode. Typically, the cell with CoB@CNT shows prominent cycling life with a capacity degradation of 0.0072% per cycle (3000 cycles) and ultrahigh-rate capability at 5 C current (1172.8 mAh/g), which outstands the previously reported polysulfides barrier layer. The cell with CoB@CNT can exhibit electrochemical performance at areal capacity of 5.5 mAh/cm (0.5 C) when the sulfur loading increased to 5.8 mg/cm. This work defines an efficacious strategy to restrain the "shuttle effect" of polysulfides and shed light on the great potential of borides in Li-S battery. 10.1021/acsnano.9b01329
    In Situ Electrochemical Mapping of Lithium-Sulfur Battery Interfaces Using AFM-SECM. Mahankali Kiran,Thangavel Naresh Kumar,Reddy Arava Leela Mohana Nano letters Although lithium-sulfur (Li-S) batteries are explored extensively, several features of the lithium polysulfides (LiPS) redox mechanism at the electrode/electrolyte interface still remain unclear. Though various in situ and ex situ characterization techniques have been deployed in recent years, many spatial aspects related to the local electrochemical phenomena of the Li-S electrode are not elucidated. Herein, we introduce the atomic-force-microscopy-based scanning electrochemical microscopy (AFM-SECM) technique to study the Li-S interfacial redox reactions at nanoscale spatial resolution in real time. In situ electrochemical and alternating current (AC) phase mappings of LiS particle during oxidation directly distinguished the presence of both conducting and insulating regions within itself. During charging, the conducting part undergoes dissolution, whereas the insulating part, predominantly LiS, chemically/electrochemically reacts with intermediate LiPS. At higher oxidation potentials, as-reacted LiPS turns into insulating products, which accumulate over cycling, resulting in reduction of active material utilization and ultimately leading to capacity fade. The interdependence of the topography and electrochemical oxidative behavior of LiS on the carbon surface by AFM-SECM reveals the LiS morphology-activity relationship and provides new insights into the capacity fading mechanism in Li-S batteries. 10.1021/acs.nanolett.9b01636
    Three-Dimensional-Ordered Porous Nanostructures for Lithium-Sulfur Battery Anodes and Cathodes Confer Superior Energy Storage Performance. Lin Shengxuan,Shafique M Khizar,Cai Zihe,Xiao Jiajia,Chen Yuhang,Wang Yifan,Hu Xiaobin ACS nano The nonuniformity of microscopic electrochemical reaction of electrodes essentially results in the partial reaction discrepancy and subsequent partial overheating, which is the most critical safety problem of the battery system in electric vehicles. Herein, we report a class of DLPC@S/DLPC@Li full cell based on a distinctly constructed double-layer photonic crystal (DLPC) with a three-dimensional-ordered interconnected structure. This full cell not only ensures the uniformity of microscopic electrochemical reaction but also solves common problems such as low conductivity of sulfur, poor cycle life, and lithium dendrite growth. Impressively, the full cell exhibits superior electrochemical performance pertaining to high reversible capacity of 703.3 mAh g even at an extremely high rate of 10 C and excellent cycle performance with 1200 cycles with about 0.0317% capacity loss per cycle at 0.5 C. 10.1021/acsnano.9b05718
    A Lithium-Sulfur Battery using a 2D Current Collector Architecture with a Large-Sized Sulfur Host Operated under High Areal Loading and Low E/S Ratio. Li Matthew,Zhang Yining,Bai Zhengyu,Liu Wen Wen,Liu Tongchao,Gim Jihyeon,Jiang Gaopeng,Yuan Yifei,Luo Dan,Feng Kun,Yassar Reza S,Wang Xiaolei,Chen Zhongwei,Lu Jun Advanced materials (Deerfield Beach, Fla.) While backless freestanding 3D electrode architectures for batteries with high loading sulfur have flourished in the recent years, the more traditional and industrially turnkey 2D architecture has not received the same amount of attention. This work reports a spray-dried sulfur composite with large intrinsic internal pores, ensuring adequate local electrolyte availability. This material offers good performance with a electrolyte content of 7 µL mg at high areal loadings (5-8 mg cm ), while also offering the first reported 2.8 µL mg (8 mg cm ) to enter into the second plateau of discharge and continue to operate for 20 cycles. Moreover, evidence is provided that the high-frequency semicircle (i.e., interfacial resistance) is mainly responsible for the often observed bypassing of the second plateau in lean electrolyte discharges. 10.1002/adma.201804271
    Highly Solvating Electrolytes for Lithium-Sulfur Batteries. Gupta Abhay,Bhargav Amruth,Manthiram Arumugam Advanced energy materials There is a critical need to evaluate lithium-sulfur (Li-S) batteries with practically relevant high sulfur loadings and minimal electrolyte. Under such conditions, the concentration of soluble polysulfide intermediates in the electrolyte drastically increases, which can alter the fundamental nature of the solution-mediated discharge and thereby the total sulfur utilization. In this work, we present an investigation into various high donor number (DN) electrolytes that allow for increased polysulfide dissolution, and demonstrate how this property may in fact be necessary for increasing sulfur utilization at low electrolyte and high loading conditions. The solvents dimethylacetamide, dimethyl sulfoxide, and 1-methylimidazole are holistically evaluated against dimethoxyethane as electrolyte co-solvents in Li-S cells, and they are used to investigate chemical and electrochemical properties of polysulfide species at both dilute and practically relevant conditions. The nature of speciation exhibited by lithium polysulfides is found to vary significantly between these concentrations, particularly in regards to the S species. Furthermore, the extent of the instability in conventional electrolyte solvents and high DN solvents with both lithium metal and polysulfides is thoroughly investigated. These studies establish a basis for future efforts into rationally designing an optimal electrolyte for a lean electrolyte, high energy density Li-S battery. 10.1002/aenm.201803096
    Use of Tween Polymer To Enhance the Compatibility of the Li/Electrolyte Interface for the High-Performance and High-Safety Quasi-Solid-State Lithium-Sulfur Battery. Liu Jie,Qian Tao,Wang Mengfan,Zhou Jinqiu,Xu Na,Yan Chenglin Nano letters Lithium metal batteries have attracted increasing attention recently due to their particular advantages in energy density. However, as for their practical application, the development of solid-state lithium metal batteries is restricted because of the poor Li/electrolyte interface, low Li-ion conductivity, and irregular growth of Li dendrites. To address the above issues, we herein report a high Li-ion conductivity and compatible polymeric interfacial layer by grafting tween-20 on active lithium metal. Sequential oxyethylene groups in tween-grafted Li (TG-Li) improve the ion conductivity and the compatibility of the Li/electrolyte interface, which enables low overpotentials and stable performance over 1000 cycles. Consequently, the poly(ethylene oxide)-based solid-state lithium-sulfur battery with TG-Li exhibits a high reversible capacity of 1051.2 mA h g at 0.2 C (1 C = 1675 mA h g) and excellent stability for 500 cycles at 2 C. The decreasing concentration of the sulfur atom with increasing Ar sputtering depth indicates that the polymer interfacial layer works well in suppressing polysulfide reduction to LiS/LiS on the metallic Li surface even after long-term cycling. 10.1021/acs.nanolett.8b01882
    Spherical Macroporous Carbon Nanotube Particles with Ultrahigh Sulfur Loading for Lithium-Sulfur Battery Cathodes. Gueon Donghee,Hwang Jeong Tae,Yang Seung Bo,Cho Eunkyung,Sohn Kwonnam,Yang Doo-Kyung,Moon Jun Hyuk ACS nano A carbon host capable of effective and uniform sulfur loading is the key for lithium-sulfur batteries (LSBs). Despite the application of porous carbon materials of various morphologies, the carbon hosts capable of uniformly impregnating highly active sulfur is still challenging. To address this issue, we demonstrate a hierarchical pore-structured CNT particle host containing spherical macropores of several hundred nanometers. The macropore CNT particles (M-CNTPs) are prepared by drying the aerosol droplets in which CNTs and polymer particles are dispersed. The spherical macropore greatly improves the penetration of sulfur into the carbon host in the melt diffusion of sulfur. In addition, the formation of macropores greatly develops the volume of the micropore between CNT strands. As a result, we uniformly impregnate 70 wt % sulfur without sulfur residue. The S-M-CNTP cathode shows a highly reversible capacity of 1343 mA h g at a current density of 0.2 C even at a high sulfur content of 70 wt %. Upon a 10-fold current density increase, a high capacity retention of 74% is observed. These cathodes have a higher sulfur content than those of conventional CNT hosts but nevertheless exhibit excellent performance. Our CNTPs and pore control technology will advance the commercialization of CNT hosts for LSBs. 10.1021/acsnano.7b05869
    A Flexible All-in-One Lithium-Sulfur Battery. Yao Minjie,Wang Rui,Zhao Zifang,Liu Yue,Niu Zhiqiang,Chen Jun ACS nano The recent boom in flexible and wearable electronic devices has increased the demand for flexible energy storage devices. The flexible lithium-sulfur (Li-S) battery is considered to be a promising candidate due to its high energy density and low cost. Herein, a flexible Li-S battery was fabricated based on an all-in-one integrated configuration, where a multiwalled carbon nanotubes/sulfur (MWCNTs/S) cathode, MWCNTs/manganese dioxide (MnO) interlayer, polypropylene (PP) separator, and Li anode were integrated together by combining blade coating with vacuum evaporation methods. Each component of the all-in-one structure can be seamlessly connected with the neighboring layers. Such an optimal interfacial connection can effectively enhance electron- and/or load-transfer capacity by avoiding the relative displacement or detachment between two neighboring components at bending strain. Therefore, the flexible all-in-one Li-S batteries display fast electrochemical kinetics and have stable electrochemical performance under different bending states. 10.1021/acsnano.8b06936
    A New Type of Electrolyte System To Suppress Polysulfide Dissolution for Lithium-Sulfur Battery. Yang Tingzhou,Qian Tao,Liu Jie,Xu Na,Li Yutao,Grundish Nicholas,Yan Chenglin,Goodenough John B ACS nano Lithium-sulfur (Li-S) batteries have been explored extensively for high-capacity electric-power storage, but their practical application has been prevented by severe issues stemming from the use of a lithium anode and an organic-liquid electrolyte in which LiS intermediates of the cell discharge reaction are soluble and shuttle to the anode. Both problems are addressed using bis(4-nitrophenyl) carbonate as an additive in the organic-liquid electrolyte. The soluble LiS polysulfides react with the additive to create insoluble polysulfides with a lithium byproduct; this byproduct reacts with the Li-metal anode to create an anode passivation layer that is a good Li conductor, which allows for safe and rapid plating/stripping of lithium metal with a low impedance. 10.1021/acsnano.9b03304
    Analysis of a Lithium/Sulfur Battery by Small-Angle Neutron Scattering. Risse Sebastian,Härk Eneli,Kent Ben,Ballauff Matthias ACS nano This study reports the use of small-angle neutron scattering to investigate processes in an operating Li/S battery. The combination with impedance spectroscopy yields valuable insights into the precipitation and dissolution of lithium sulfide during 10 cycles of galvanostatic cycling. The use of a deuterated electrolyte increases strongly the sensitivity to detect the sulfur and LiS precipitates at the carbon host electrode and allows us to observe the time-dependent initial wetting of the system. No correlation of the scattering signal of the micropores with either lithium sulfide or sulfur is observable during the whole course of the experiment. Hence both reaction products do not precipitate inside the microporous structure but on the outer surface of the micrometer-sized carbon fibers used in this study. The excellent scattering contrast allows a detailed analysis of the formation and dissolution process of nanoscopic LiS structures. While lithium sulfide particles grow homogeneously during the precipitation period, smaller LiS particles dissolve first followed by a sudden dissolution of the larger LiS particles. 10.1021/acsnano.9b03453
    Programmed Design of a Lithium-Sulfur Battery Cathode by Integrating Functional Units. Zeng Zhipeng,Li Wei,Wang Qiang,Liu Xingbo Advanced science (Weinheim, Baden-Wurttemberg, Germany) Sulfur is considered to be one of the most promising cathode materials due to its high theoretical specific capacity and low cost. However, the insulating nature of sulfur and notorious "shuttle effect" of lithium polysulfides (LiPSs) lead to severe loss of active sulfur, poor redox kinetics, and rapid capacity fade. Herein, a hierarchical electrode design is proposed to address these issues synchronously, which integrates multiple building blocks with specialized functions into an ensemble to construct a self-supported versatile cathode for lithium-sulfur batteries. Nickel foam acts as a robust conductive scaffold. The heteroatom-doped host carbon with desired lithiophilicity and electronic conductivity serving as a reservoir for loading sulfur can trap LiPSs and promote electron transfer to interfacial adsorbed LiPSs and NiS sites. The sulfurized carbon nanofiber forest can facilitate the Li-ion and electron transport and retard the LiPSs diffusion as a barrier layer. Sulfiphilic NiS acts as both a chemical anchor with strong adsorption affinity to LiPSs and an efficient electrocatalyst for accelerating kinetics for redox conversion reactions. Synergistically, all functional units promote the lithium ion coupled electron transfer for binding and redox conversion of LiPSs, resulting in high reversible capacities, remarkable cycle stability, and excellent rate capability. 10.1002/advs.201900711
    Simultaneous Suppression of the Dendrite Formation and Shuttle Effect in a Lithium-Sulfur Battery by Bilateral Solid Electrolyte Interface. Fan Ling,Chen Suhua,Zhu Jingyi,Ma Ruifang,Li Shuping,Podila Ramakrishna,Rao Apparao M,Yang Gongzheng,Wang Chengxin,Liu Qian,Xu Zhi,Yuan Lixia,Huang Yunhui,Lu Bingan Advanced science (Weinheim, Baden-Wurttemberg, Germany) Although the reversible and inexpensive energy storage characteristics of the lithium-sulfur (Li-S) battery have made it a promising candidate for electrical energy storage, the dendrite growth (anode) and shuttle effect (cathode) hinder its practical application. Here, it is shown that new electrolytes for Li-S batteries promote the simultaneous formation of bilateral solid electrolyte interfaces on the sulfur-host cathode and lithium anode, thus effectively suppressing the shuttle effect and dendrite growth. These high-capacity Li-S batteries with new electrolytes exhibit a long-term cycling stability, ultrafast-charge/slow-discharge rates, super-low self-discharge performance, and a capacity retention of 94.9% even after a 130 d long storage. Importantly, the long cycle stability of these industrial grade high-capacity Li-S pouch cells with new electrolytes will provide the basis for creating robust energy dense Li-S batteries with an extensive life cycle. 10.1002/advs.201700934
    Solar-Driven Rechargeable Lithium-Sulfur Battery. Chen Peng,Li Guo-Ran,Li Tian-Tian,Gao Xue-Ping Advanced science (Weinheim, Baden-Wurttemberg, Germany) Solar cells and rechargeable batteries are two key technologies for energy conversion and storage in modern society. Here, an integrated solar-driven rechargeable lithium-sulfur battery system using a joint carbon electrode in one structure unit is proposed. Specifically, three perovskite solar cells are assembled serially in a single substrate to photocharge a high energy lithium-sulfur (Li-S) battery, accompanied by direct conversion of the solar energy to chemical energy. In the subsequent discharge process, the chemical energy stored in the Li-S battery is further converted to electrical energy. Therefore, the newly designed battery is capable of achieving solar-to-chemical energy conversion under solar-driven conditions, and subsequently delivering electrical energy from the stored chemical energy. With an optimized structure design, a high overall energy conversion efficiency of 5.14% is realized for the integrated battery. Moreover, owing to the self-adjusting photocharge advantage, the battery system can retain high specific capacity up to 762.4 mAh g under a high photocharge rate within 30 min, showing an effective photocharging feature. 10.1002/advs.201900620
    Assembling Carbon Pores into Carbon Sheets: Rational Design of Three-Dimensional Carbon Networks for a Lithium-Sulfur Battery. Feng Shuo,Song Junhua,Zhu Chengzhou,Shi Qiurong,Liu Dong,Li Jincheng,Du Dan,Zhang Qiang,Lin Yuehe ACS applied materials & interfaces The conversion reaction-based lithium-sulfur battery features an attractive energy density of 2600 W h/kg. Nevertheless, the unsatisfied performance in terms of poor discharge capacity and cycling stability still hinders its practical applications. Recently, porous carbon materials have been widely reported as promising sulfur reservoirs to promote the sluggish reaction kinetics of sulfur conversion, tolerate volume expansion of sulfur, and suppress polysulfide shuttling. However, porous carbon with a simply designed nanostructure is hard to satisfy all of these aspects simultaneously. Herein, we have applied a dual-template strategy that assembles carbon pores into carbon sheets to prepare three-dimensional (3D) nitrogen-doped porous carbon nanosheets (N-PCSs) as the multifunctional sulfur host for the Li-S battery. By arranging carbon pores within an interconnected 3D architecture, the porous carbon sheets enable rapid electron/ion transfer. Moreover, the micro/mesopores and nitrogen dopant in N-PCS provide both physical and chemical restrictions to polysulfide species. With these advances, the N-PCS/S cathode delivers a large initial discharge capacity of 1360 mA h/g at 0.1 C. When performed at 0.5 C for 1000 cycles, the cathode can still remain ∼50% of its capacity with a low decay rate of 0.05% per cycle, showing the important role of the 3D carbon material in the Li-S battery. 10.1021/acsami.8b17549
    Atomic Interlamellar Ion Path in High Sulfur Content Lithium-Montmorillonite Host Enables High-Rate and Stable Lithium-Sulfur Battery. Chen Wei,Lei Tianyu,Lv Weiqiang,Hu Yin,Yan Yichao,Jiao Yu,He Weidong,Li Zhenghan,Yan Chenglin,Xiong Jie Advanced materials (Deerfield Beach, Fla.) Fast lithium ion transport with a high current density is critical for thick sulfur cathodes, stemming mainly from the difficulties in creating effective lithium ion pathways in high sulfur content electrodes. To develop a high-rate cathode for lithium-sulfur (Li-S) batteries, extenuation of the lithium ion diffusion barrier in thick electrodes is potentially straightforward. Here, a phyllosilicate material with a large interlamellar distance is demonstrated in high-rate cathodes as high sulfur loading. The interlayer space (≈1.396 nm) incorporated into a low lithium ion diffusion barrier (0.155 eV) significantly facilitates lithium ion diffusion within the entire sulfur cathode, and gives rise to remarkable nearly sulfur loading-independent cell performances. When combined with 80% sulfur contents, the electrodes achieve a high capacity of 865 mAh g at 1 mA cm and a retention of 345 mAh g at a high discharging/charging rate of 15 mA cm , with a sulfur loading up to 4 mg. This strategy represents a major advance in high-rate Li-S batteries via the construction of fast ions transfer paths toward real-life applications, and contributes to the research community for the fundamental mechanism study of loading-independent electrode systems. 10.1002/adma.201804084
    Simultaneously Porous Structure and Chemical Anchor: A Multifunctional Composite by One-Step Mechanochemical Strategy toward High-Performance and Safe Lithium-Sulfur Battery. Zhu Zhao-Yan,Yang Na,Chen Xiao-Shuan,Chen Si-Chong,Wang Xiu-Li,Wu Gang,Wang Yu-Zhong ACS applied materials & interfaces A lithium-sulfur (Li-S) battery has been regarded as one of the most promising energy-storage systems to meet requirements for high energy density in electric vehicles, advanced portable electronic devices, and so on. However, practical application of a Li-S battery is restricted severely by easy dissolution of lithium polysulfides and high flammability of sulfur. Herein, we developed, for the first time, a multifunctional composite directly prepared by a facile, green, low-cost, and large-scale ball-milling method with fly ash and sulfur. Due to the unique microstructure and sulfur-related components as chemical anchors, composites possessed good electron/ion transport, favorable resistance to volume change of sulfur, and strong chemical affinity to polysulfides, which greatly facilitate redox kinetics, maintain structural integrity of the cathode, and suppress polysulfide shuttling in electrolyte, hence significantly boosting electrochemical performance of the Li-S battery with high initial discharge capacity, superior cycling stability, and satisfying rate capability. Typically, Li-S batteries based on a composite with a sulfur loading of 86.9% present initial discharge capacities of 969.8, 894.3, and 769.7 mAh g as well as capacity decay rates of 0.068% (400 cycles), 0.1% and 0.042% per cycle (200 cycles) at 0.2, 0.5, and 1 C, respectively. Moreover, the average specific self-extinguishing time of the composite-based cathode was clearly reduced to less than half of that of the pristine sulfur-based cathode, indicating significantly promoting the safety of the battery. 10.1021/acsami.8b14947
    Metal-Organic-Framework-Based Gel Polymer Electrolyte with Immobilized Anions To Stabilize a Lithium Anode for a Quasi-Solid-State Lithium-Sulfur Battery. Han Dian-Dian,Wang Zhen-Yu,Pan Gui-Ling,Gao Xue-Ping ACS applied materials & interfaces A lithium-sulfur (Li-S) battery is widely regarded as one of the most promising technologies for energy storage because of its high theoretical energy density and cost advantage. However, the shuttling of soluble polysulfides between the cathode and the anode and the consequent lithium anode degradation strongly limit the safety and electrochemical performance in the Li-S battery. Herein, a metal-organic-framework (MOF)-modified gel polymer electrolyte (GPE) is employed in a Li-S battery in order to stablize the lithium anode. In view of the abundant pores in the MOF skeleton, the as-prepared GPE not only immobilizes the large-size polysulfide anions but also cages electrolyte anions into the pores, thus facilitating a uniform flux of Li ions and homogeneous Li deposition. Cooperated with a sulfur-carbon composite cathode, the lithium with MOF-modified GPE exhibits a uniform surface morphology and dense solid electrolyte interphase (SEI) film, thus delivering good cycle stability and high-rate capability. 10.1021/acsami.9b03682
    Cathode porosity is a missing key parameter to optimize lithium-sulfur battery energy density. Kang Ning,Lin Yuxiao,Yang Li,Lu Dongping,Xiao Jie,Qi Yue,Cai Mei Nature communications While high sulfur loading has been pursued as a key parameter to build realistic high-energy lithium-sulfur batteries, less attention has been paid to the cathode porosity, which is much higher in sulfur/carbon composite cathodes than in traditional lithium-ion battery electrodes. For high-energy lithium-sulfur batteries, a dense electrode with low porosity is desired to minimize electrolyte intake, parasitic weight, and cost. Here we report the profound impact on the discharge polarization, reversible capacity, and cell cycling life of lithium-sulfur batteries by decreasing cathode porosities from 70 to 40%. According to the developed mechanism-based analytical model, we demonstrate that sulfur utilization is limited by the solubility of lithium-polysulfides and further conversion from lithium-polysulfides to LiS is limited by the electronically accessible surface area of the carbon matrix. Finally, we predict an optimized cathode porosity to maximize the cell level volumetric energy density without sacrificing the sulfur utilization. 10.1038/s41467-019-12542-6