Lithium-sulfur battery system possesses high capacity and high energy density in theory, but which cannot be realized fully due to the insulating nature of the cathode material itself and the dissolution of its intermediate products. The cycle performances of lithium-sulfur battery are also deteriorated owing to these disadvantages. Modification of the cathode material is the major approach to address the issues described above. Here, combining the polysulfides limiting mechanism, we give a brief review of recent progress on the cathode materials of lithium-sulfur battery, which are classified into three kinds, including nano-carbon/sulfur composites, polymer/sulfur composites and nano-metal compound/sulfur composites, list the representative work, and review the advantages/disadvantages of various cathode materials. From the practical point of view, we suggest that the evaluating to the performances of the cathode materials should be related with some special conditions, such as the sulfur loading, sulfur content of cathode, and the electrolyte amount in battery. Furthermore, we explain the design strategy for high performance cathode materials. It is pointed out that the high electrolyte amount is the key factor which restricts the further enhancement of the specific energy of lithium sulfur battery. At last, the development trend of lithium sulfur battery is prospected.

 With the increasing demand for efficient and economic energy storage, lithium-sulfur (Li-S) batteries have become attractive candidates for the next-generation high-energy rechargeable batteries because of their high theoretical energy density and cost effectiveness. However, practical applications of the Li-S battery are hindered by poor cycle life, low coulombic efficiency, self-discharge, et al. Main reason of these issues is the polysulfide shuttle, which caused by the dissolution of polysulfides into the electrolyte and deposition on the lithium anode. Several strategies have been proposed in order to tackle these issues and improve the overall electrochemical performance of the Li-S batteries. In particular, among them, the preparation of sulfur hybrid materials by different carbon materials or various functional carbon based materials is frequently used. In this review, we present fundamental studies and technological development of various cathode materials for Li-S batteries, including their preparation, structure, morphology and battery performance. Based on the adsorption characteristics between the host and polysulfide, the materials are divided into two types: physical adsorption and chemical adsorption. Adjusting or functionalizing the electrode materials can effectively promote the performance of the Li-S batteries, and the mechanism is further revealed to gain a better understanding of the characteristics between the host and polysulfide. Finally, we give insights on the relation between the structure of the cathode materials and the electrochemical performance of the Li-S batteries and the critical research directions needed for lithium sulfur batteries to be addressed are summarized.

 With the development of emerging flexible electronic devices, high performance flexible power sources have attracted great attention. Lithium sulfur battery with merits in high energy density and low cost holds promise in application in next generation flexible energy battery system. Flexible electrodes are key components in flexible batteries, which serve as electronic conductive skeleton, ion conduction skeleton, and active material hosts. In this paper, the characteristics of lithium-sulfur battery and its flexible cathode are briefly introduced, and the research progress of flexible cathode material for lithium-sulfur battery is reviewed. The future research direction and development space of lithium-sulfur battery are prospected.

Lithium-sulfur (Li-S) battery, has attracted tremendous attention from the energy storage community, mainly due to its high theoretical energy density (～2600 W·h·kg1), which is twice more than that of conventional Li-ion batteries. However, the commercialization of Li-S battery technology is hindered by technical obstacles, such as the poor intrinsic electronic conductivity of sulfur and final discharge products (Li2S/Li2S2), the high dissolution of intermediate product lithium polysulphides (LiPSs), large volumetric expansion (76%) of sulfur cathode during the lithiation, and the irreversible phase transformation and uncontrolled deposition of Li2S. Fortunately, intense research efforts have been devoted to overcoming these unsolved issues. Among these efforts, the most effective strategy is constructing nanocomposite cathodes composed of sulfur with surface and interface decorated carbonaceous materials. Carbon materials with modified surfaces and interfaces for advanced Li-S batteries are summarized in this paper.

The development of lithium-sulfur batteries has been hindered by the poor conductivity of sulfur and the dissolution of intermediate species (lithium polysulfides) into the electrolyte. In this study, MnO2@MWCNT-S was synthesized by impregnating multi-walled carbon nanotubes (MWCNT) with sulfur, followed by the coating of manganese dioxide (MnO2) on the surface. MWCNT can provide electronic conductive path to improve the conductivity of electrode material, while MnO2 has strong chemical adsorption to the polysulfide, thereby inhibiting the dissolution of polysulfide and enhancing the utilization of active materials. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization show that sulfur is uniformLy distributed across the carbon nanotubes and their surface is covered by a layer of manganese dioxide. The content of sulfur in MnO2 @MWCNT-S composites is 58.4% by thermogravimetric analysis (TGA). Electrochemical testing indicated that MnO2 coating has improved the initial capacity of MWCNT-S composite and effectively retarded the dissolution of polysulfides. The MnO2@MWCNT-S composite showed a high initial discharge capacity of 1148.98 mA·h·g-1 and maintained 560.04 mA·h·g-1 after 100 cycles at 0.1 C rate.

As the increasing demands of energy storage devices, high energy density rechargeable batteries have been strongly considered. Thanks to the low mass density, high theoretical specific energy density, and lowest redox potential, metallic lithium becomes one of the most promising anode materials to build high-performance rechargeable batteries. However, the formation of lithium dendrites causes rapid capacity degradation, short cycle life, and potential safety hazard of working lithium batteries. This hinders its practical applications. In-situ observation is highly beneficial to explore the growth mechanism of lithium dendrites and improve the battery performance. In this review, the progress on in-situ observation devices, their applications in Li dendrite observation and the obtained models for dendrite growth are summarized. Finally, the perspective of lithium metal anode through in-situ/operando characterization is discussed.

The rapid developments of electronic devices and electric vehicles have driven the ever increasing demands on high energy density energy storage system. Lithium-sulfur (Li-S) batteries have been strongly considered due to their high theoretical specific energy density, low cost of active materials, and excellent environmental benignity. However, the electrochemical performance of Li-S batteries suffers from a low coulombic efficiency, a rapid capacity degradation, and unstable anode-electrolyte interfaces, etc. The incorporation of rationally designed composite separator system is beneficial to mitigate these shortcomings towards the practical applications of Li-S batteries. In this contribution, the recent processes of composite separators with functional materials (such as carbon, polymer, inorganic compound, etc.) and novel structures were reviewed. The prospects for the development of separator in Li-S system are also involved.

Currently lithium sulfur (Li-S) batteries are recognized as the most promising novel secondary battery candidates due to their high energy density, abundant sulfur and environment benign. The functional electrolyte is a major component of Li-S batteries, which physical property characteristics are closely related to the electrochemical performance of Li-S batteries. Nevertheless, its development is restricted by some key technologies. The polysulfides dissolve into electrolytes and cause the consequent shuttle phenomenon, resulting in low coulombic efficiency, fast capacity fade and serious self-discharge of Li-S batteries. This paper reviews the recent research progress for these problems of the electrolytes for Li-S batteries. ① the modification and optimization of the solvent components, lithium salts and additives of the organic liquid electrolytes to improve the performance of Li-S batteries, ② the effect on polysulfides dissolution by ionic liquid electrolytes, and ③ the suppression of the shuttle effects by (semi-) solid-state electrolytes. Finally, the future research trends of the functional electrolytes for Li-S electrolytes are proposed.

The development of electronic devices, such as portable electronics, electric vehicles and smart grids, brings new requirements and challenges to electrochemical energy storage system. Solid state lithium-sulfur batteries have attracted much attention for their high theoretical energy density and safety properties. Owning to high ionic conductivity and excellent interface contact, sulfide solid electrolytes are suitable for solid state lithium-sulfur batteries. This review summarizes the recent progress of solid state lithium-sulfur batteries with sulfide solid electrolytes. It focuses on the properties of sulfide solid electrolytes, the formation of efficient carrier pathways on the cathode side, and the stable lithium/electrolyte interfaces on the anode side. The future development directions of solid state lithium-sulfur batteries with sulfide solid electrolytes are also prospected.

Utilizing solid state electrolytes instead of traditional liquid electrolytes has been expected to simultaneously solve the polysulfide shuttle, lithium dendrites growth, low thermal stability and other important scientific and technical problems of lithium-sulfur batteries. However, the solid electrolyte has various disadvantages such as low ionic conductivity at room temperature, poor electrolyte/electrode interface compatibility, hindering the commercial development of lithium-sulfur batteries. This article presents a brief review of the researches on the gel polymer electrolyte, all solid polymer electrolyte and composite electrolyte for solid state lithium-sulfur batteries. At the same time, combining with theoretical models and micro-mechanism, this review illustrates the mechanism of lithium ionic conductivity in the solid polymer electrolyte, the inhibition of polysulfide shuttle and dendrite growth by the solid electrolyte in detail. The problems and future development of solid polymer electrolyte in lithium-sulfur batteries are also systematically summarized and outlooked.

Water soluble binder has caused extensive concern because of its environmentally friendly, low cost and safety, etc. Cathode slurry can not be configured bacause the agar binder is almost insoluble in water at room temperature. The hydroxyl groups of agar (AG) were partially oxidized to carboxyl groups by H2O2. Oxidized agar (M-AG) can be easily dissolved in water at room temperature. The presence of carboxyl groups may adsorb lithium polysulfide, which inhibits the "shuttle" of lithium polysulfide during the charging and discharging process. In this work, the M-AG was used as binder in lithium-sulfur battery. The good contact among the active material, the conductive agent and the current collector can be well preserved with M-AG as binders. The M-AG does not participate the electrochemical reaction in lithium-sulfur battery. The structure of the electrode can be stabilized during the repeated charging and discharging process. The M-AG electrode has higher capacity release and capacity retention than the conventional PVDF electrode. It delivers an initial specific discharge capacity of 700 mA·h·g1 with a high capacity retention ratio of 90.7% after 100 cycles.

Lithium-sulfur (Li-S) batteries are strongly considered as next-generation energy storage devices for its extremely high energy capacity compared with traditional lithium ion batteries (LIBs). However, several issues such as the shuttle of polysulfides, the instability of electrolyte, and the growth of lithium dendrites restrict their practical applications. The development of first-principles method has promoted the understanding of the key questions in Li-S batteries and their practical process. This paper reviews the applications of density functional theory, Hartree-Fock method, and ab initio molecular dynamics in Li-S batteries cathode, electrolyte, and anode. At last, a conclusion is draw and a perspective is present for first-principles calculation.

 lithium-sulfur (Li-S) batteries with low cost, long life, high energy, and environmental benignity promise great potential to be the next-generation high-energy system. However, the practicality of Li-S technology is hindered by various obstacles, such as rapid capacity fading along with low coulombic efficiency arising from high solubility of long-chain lithium polysulfides and the shuttle effect in lithium sulfur battery. During the cycling, the generated polysulfides can be measured quickly and accurately by UV/vis analysis, which plays an important role in the analysis of Li-S batteries. This paper mainly introduced the newest applications of in-situ UV/vis analysis in Li-S batteries as well as the qualitative and quantitative analysis of the generated polysulfides during charge and discharge process.

 Lithium-sulfur (Li-S) primary battery, consisting of a sulfur positive and a Li-metal negative electrodes, can be one of the promising primary battery system for its high energy density, long life, good security and low cost. Unlike the Li-S secondary battery facing poor cyclic life and serious self-discharge problems, Li-S primary battery has great application potential in consumer electronics power supplies, UPS and power supplies. From the view of practical application, this article introduced the research status and future development prospect of Li-S primary batteries, and further appealed for extensive attention to this field.

 The conventional lithium-ion batteries are unable to meet the increasing demands for high-energy storage systems, because of their limited theoretical capacity. In recent years, intensive attentions have been paid on lithium-sulfur battery worldwide by researchers, due to its step-change improvement in capacity（1673 mA·h·g−1），which is 4 times higher than current lithium ion batteries. In response to the low electronic/ionic conductivity of sulfur, the dissolution of the polysulfide, the huge volume changes during cycling and so on, researchers have focused on the design of smart cathode structures, the protection of lithium anode, and the optimization of electrolyte and separators. These strategies successfully inhibit the polysulfide shuttling problem, increase the utilization of active substances, buffer the large volume change and improve the safety and cycle life. In this paper, we review the recent developments in lithium-sulfur batteries, highlight typical novel technologies such as polar-polar interactions to control polysulfide dissolution, artificial SEI to protect the lithium anode, novel electrolyte and separator to suppress polysulfide shuttling, and forecast the directions for its future developments.

 The emergence of lithium-sulfur (Li-S) battery accelerates the development of high-energy energy storage devices, but the intrinsic properties of sulfur are the bottlenecks for high-performance Li-S battery. The employment of conductive carbon nanomaterials improves the performance of sulfur electrode significantly, while the energy density both calculated from mass or volume is far below the expected value. Densified sulfur/carbon electrode with high sulfur content is the key to solve this issue, and starting from the materials design to densify the materials, the electrode and lighten the device is a promising principle to pave the avenue towards compact Li-S battery. This contribution discusses the research principles for compact energy storage in Li-S battery, and proposes the solution-based assembly as the high-efficiency approach to realize the high volumetric performance. The recent advances for high-volumetric performance Li-S battery are presented here and future application of Li-S batteries in marine science and aerospace science is commented.

Lithium-sulfur (Li-S) battery employing lithium as the anode and sulfur as the cathode possesses the highest theoretical energy density of 2600 W·h·kg-1 among the rechargable batteries consisted by the solid-state active materials. Sulfur and lithium resources are also abundant and low cost. To replace the organic liquid electrolyte by the solid electrolyte, the all-solid-state battery systems are expected to solve the safety issues and improve the cycling stability of Li-S batteries. It is becoming the hot topic in reaseach and development of rechargeable batteries. This paper presents a comprehensive review of the progress of all solid-state Li-S batteries in recent years, including solid electrolytes, sulfur-based cathodes, lithium-based anodes, electrode/electrolyte interface, and cell fabrication methods. The developments of all solid-state Li-S batteries are prospected as well.

This bimonthly review paper highlights 100 recent published papers on lithium batteries. We searched the Web of Science and found 2196 papers online from Feb. 1, 2017 to Mar. 31, 2017. 100 of them were selected to be highlighted. Layered oxide and high voltage spinel cathode materials are still under extensive investigations for studying Li+ intercalation-deintercalation mechanism and evolution of surface structure, and the influences of doping, coating and interface modifications on their cycling performances. Large efforts were devoted to Si based composite and metallic lithium anode materials. In-situ technologies are used to analyze the kinetic process and SEI and theoretical work covers the machnism for Li storage, kinetics, SEI and solid state electrolytes. There are a few papers related to electrolyte additives, solid state electrolyte, lithium batteries, Li/S batteries, Li-air batteries, and modeling.

Li4Ti5O12 (LTO)-based battery has been considered as next generate energy storage battery for grid applications due to its excellent rate cyclic properties and cycle life. But up to now there is no capacity fading model which is suitable for LTO-based battery has been reported. We tested commercial LTO battery (nominal capacity of 10 A·h, 2.2～3.2 V rating). The cells were tested at different rate for more than 4800 cycles, the irreversible capacity loss of battery was measured at 0.1 C to eliminate the polarization effect after each 600 cycles. The test data was then used to develop an empirical model by curve-fitting and regression techniques. It can be used to predict the rated capacity loss due to polarization and irrevisible capacity loss caused by loss of active lithium.

In this study, PVDF-HFP-based porous polymer electrolyte membranes for lithium-ion battery have been prepared by non-solvent evaporate method, and the effects of different volatility temperature ethylene glycol on the structure and properties of porous polymer electrolyte membranes were examined. The membranes were characterized by scanning electron microscopy (SEM), different scanning calorimetry (DSC), mechanical strength test, electrochemical impedance spectroscopy (EIS). The results show that volatility temperature ethylene glycol has significant influences on the physical and electrochemical properties of porous polymer electrolyte membranes. It is found that the membrane with good appearance cannot be obtained at lower temperature. The membranes showed honeycomb-like macroporous morphology on the cross-section. When temperature increased from 60 to 100 ℃, the tensile strength increased from 6.49 to 21.39 MPa, and the ionic conductivity at room temperature decreased from 1.07 to 0.14 mS·cm-1. So with volatility temperature ethylene glycol of 70～90 ℃, it is more suitable for preparing PVDF-HFP porous electrolyte membranes via non-solvent evaporate method.

LiNi1-x-yCoxMnyO2 cathode material for lithium-ion battery is one of the promising cathode materials due to its larger discharge capability and good cycle performance as compared with a single component layered materials such as lithium cobaltate, lithium nickelate and lithium manganate, especially under the environment of global sustainable development of new energy industry. In order to review the development of nickel cobalt manganese based cathode material(NCM) for lithium-ion battery in the world and China, patents from domestic and overseas on the NCM for lithium-ion battery are analyzed, based on the searching results from the Derwent Word Patent Index database(DWPI) and China Patent Abstract Database(CNABS). This report focuses on the analysis of the aspects of patents application trend, preparation methods and technical effectiveness, important applicants, technology development route and core patent. The results show that patent applications of NCM around the world and China are increasing, but there is no obvious increase in the number of foreign applications in China recently. The development of domestic started late, the basic and core patents are lacking, and the gap between Chinese applications and Japanese/Korean applications is large. The preparation method is mainly co-precipitation and solid-phase reaction, and the modification is mainly focused to improve the electrochemical performance. However, there is no effective breakthrough in terms of safety and cost issues. Based on these, some suggestions are put forward on the patent layout of NCM for lithium-ion battery of our country in the future.