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The market share in electric vehicles (EV) is increasing. This trend is likely to continue due to the increased interest in reducing CO 2 emissions. The electric vehicle market evolution depends principally on the evolution of batteries capacity. As a consequence, automobile manufacturers focus their efforts on launching in the market EVs capable to compete with internal combustion engine vehicles (ICEV) in both performance and economic aspects. Although EVs are suitable for the day-to-day needs of the typical urban driver, their range is still lower than ICEV, because batteries are not able to store and supply enough energy to the vehicle and provide the same autonomy as ICEV. EV use mostly Lithium-ion (Li-ion) batteries but this technology is reaching its theoretical limit (200-250 Wh/kg). Although the research to improve Li-ion batteries is very active, other researches began to investigate alternative electrochemical energy storage systems with higher energy density. At present, the most promising technology is the Lithium-Sulphur (Li-S) battery. This paper presents a review of the state of art of Li-Sulphur battery on EVs compared to Li-ion ones, considering technical, modelling, environmental and economic aspects with the aim of depicting the challenges this technology has to overcome to substitute Li-ion in the near future. This study shows how the main drawbacks for Li-S concern are durability, self-discharge and battery modelling. However, from an environmental and economic point of view, Li-S technology presents many advantages over Li-ion., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

[Display omitted] The application of Li-S batteries on large scale is held back by the sluggish sulfur kinetics and low synthesis efficiency of sulfur host. In addition, the preparation of catalysts that promote polysulfide redox kinetics is complex and time-consuming, reducing the cost of raw materials in Li-S. Here, a universal synthetic strategy for rapid fabrication of sulfur cathode and metal compounds nanocatalysts is reported based on microwave heating of graphene. Heat-sensitive materials can achieve rapid heating due to graphene reaching 500 ℃ within 4 s via microwave irradiation. The MoP-MoS 2 /rGO catalyst demonstrated in this work was synthesized within 60 s. When used for catalysts for Li-S batteries whose graphene/sulfur cathodes were also synthesized by microwave heating, enhanced catalytic effect for sulfur redox reaction was verified via experimental and DFT theoretical results. Benefiting from fast redox reaction (MoP), smooth Li+ diffusion pathways (MoS 2), and large conductive network (rGO), the assembled Li-S battery with MoP-MoS 2 /rGO-Add@CS displays a remarkable initial specific capacity, stable lithium anode and good cycle stability (in pouch cells) using this two-pronged strategy. The work provides a practical strategy for advanced Li-S batteries toward a wide range of applications. [ABSTRACT FROM AUTHOR]

The performance of Lithium–sulfur (Li–S) batteries is constrained by the migration of lithium polysulfide (LiPS), the slow conversion of LiPS, and the significant reaction barrier encountered during the precipitation/dissolution of Li2S throughout the discharge/charge cycle. In this contribution, the study presents Ni–Co dual‐atom catalytic sites on hollow nitrogen‐doped carbon (NiCoNC). Theoretical calculations and experimental data reveal that the dual‐atom catalysts (DACs) accelerate the kinetic conversion of LiPSs and facilitate the formation/decomposition of Li2S during discharging and charging, which minimizes LiPS migration. Consequently, the utilization of S/NiCoNC cathodes manifests a substantial initial capacity of 1348.5 mAh g−1 at 0.1 C, exceptional cycling stability with an average capacity degradation rate of 0.028% per cycle over 900 cycles at 0.5 C, and noteworthy rate capability with a capacity of 626 mAh g−1 at 2 C. Electrodes with a higher sulfur loading of 4.5 mg cm−2 and a low electrolyte/sulfur ratio of 8 µL mg−1 exhibit exceptional specific capacities of up to 1236 mAh g−1 at 0.1 C, as well as noteworthy capacity retention of 494.2 mAh g−1 after 200 cycles at 0.2 C. This study effectively showcases the potential of DACs as catalysts for sulfur cathodes, thereby enhancing the overall performance of Li–S batteries. [ABSTRACT FROM AUTHOR]

Li‐S batteries possess high energy density and have been one of the most promising energy storage systems. For sulfur cathodes, the electrochemical performance is still seriously hindered by the polysulfide shuttling and sluggish conversion kinetics. It has been demonstrated to be one effective strategy to address the above issues via designing electrocatalysts with robust affinity and catalytic capacity towards polysulfides. However, it is still a great challenge to rapidly and economically discover high‐performance electrocatalysts. Herein, using density functional theory calculation, we studied the chemisorption‐catalysis behavior of sulfur species on a series of electrocatalysts (MCo2X4, M=Co, Zn, Cu, Ni, Fe, and Mn, X=O, S, and Se) to assess the effect of the anions and cations co‐regulation on their electronic structure, chemisorption behavior, and catalytic property. FeCo2Se4 and CuCo2Se4 combined appropriate chemisorption with superior electronic conductivity and sulfur reduction catalytic capacity have been predicted as novel electrocatalysts for high‐performance Li‐S batteries. This study gives theoretical guidance for rapid discovery of high‐efficient electrocatalyst to boost the electrochemical performance of sulfur cathodes. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries offer the potential for significantly higher energy density and cost-effectiveness. However, their progress has been hindered by challenges such as the "shuttle effect" caused by lithium polysulfides and the volume expansion of sulfur during the lithiation process. These limitations have impeded the widespread adoption of lithium–sulfur batteries in various applications. It is urgent to explore the high-performance sulfur host to improve the electrochemical performance of the sulfur electrode. Herein, bimetallic NiFe hydroxide (NiFe-LDH)-modified carbon nanotubes (CNTs) are prepared as the sulfur host materials (NiFe-CNT@S) for loading of sulfur. On the one hand, the crosslinked CNTs can increase the electron conductivity of the sulfur host as well as disperse NiFe-LDHs nanosheets. On the other hand, NiFe-LDHs command the capability of strongly adsorbing lithium polysulfides and also accelerate their conversion, which effectively suppresses the shuttle effect problem in lithium polysulfides. Hence, the electrochemical properties of NiFe-CNT@S exhibit significant enhancements when compared with those of the sulfur-supported pure NiFe-LDHs (NiFe-LDH@S). The initial capacity of NiFe-CNT@S is reported to be 1010 mAh g−1. This value represents the maximum amount of charge that the material can store per gram when it is first synthesized or used in a battery. After undergoing 500 cycles at a rate of 2 C (1 C = 1675 mA g−1), the NiFe-CNT@S composite demonstrates a sustained capacity of 876 mAh g−1. Capacity retention is a measure of how well a battery or electrode material can maintain its capacity over repeated charge–discharge cycles, and a higher retention percentage indicates better durability and stability of the material. [ABSTRACT FROM AUTHOR]

[Display omitted] In this work, a new cathode material for lithium–sulfur (Li–S) batteries was developed. Microporous carbon (with predominant pore size £ 1.2 nm) served as both a matrix for sulfur retention and conductive additive. Microporous carbon was shown to be capable of adsorbing lithium polysulfides thereby suppressing their migration toward lithium anode. The discharge capacity of the S/C composite at the 1st and 20th cycles in Li–S battery operation was 513 and 421 mAh g–1 at a scan rate of 0.1 mV s–1. [ABSTRACT FROM AUTHOR]

Highlights: The electrochemical principles/mechanism of Li–S batteries and origin of the shuttle effect have been discussed. The efficient strategies have been summarized to inhibit the shuttle effect. The recent advances of inhibition of shuttle effect in Li–S batteries for all components from anode to cathode. Lithium–sulfur (Li–S) batteries are supposed to be one of the most potential next-generation batteries owing to their high theoretical capacity and low cost. Nevertheless, the shuttle effect of firm multi-step two-electron reaction between sulfur and lithium in liquid electrolyte makes the capacity much smaller than the theoretical value. Many methods were proposed for inhibiting the shuttle effect of polysulfide, improving corresponding redox kinetics and enhancing the integral performance of Li–S batteries. Here, we will comprehensively and systematically summarize the strategies for inhibiting the shuttle effect from all components of Li–S batteries. First, the electrochemical principles/mechanism and origin of the shuttle effect are described in detail. Moreover, the efficient strategies, including boosting the sulfur conversion rate of sulfur, confining sulfur or lithium polysulfides (LPS) within cathode host, confining LPS in the shield layer, and preventing LPS from contacting the anode, will be discussed to suppress the shuttle effect. Then, recent advances in inhibition of shuttle effect in cathode, electrolyte, separator, and anode with the aforementioned strategies have been summarized to direct the further design of efficient materials for Li–S batteries. Finally, we present prospects for inhibition of the LPS shuttle and potential development directions in Li–S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • •Highly dispersed CoO nanoparticles are formed in the inner channels of biochar by microwave-assisted treatment. • •Conductive network of biochar matrix can efficiently improve activation of the infused sulfur. • •Kinetics of polysulfides conversion and Li+ diffusion can be greatly enhanced by the CoO nanoparticles. • •The functionalized sulfur electrode exhibits the improved rate capability and excellent cycling stability. A new strategy is developed to fabricate sulfur electrode by infusing sulfur into a conductive biochar decorated with highly dispersed CoO nanoparticles. The loading of the CoO nanoparticles, as the active sites for reactions, is efficiently increased by using the microwave-assisted diffusion method. It is demonstrated that biochar can serve as an excellent conductive framework to effectively activate sulfur. Simultaneously, the CoO nanoparticles possessing excellent capability to adsorb polysulfides can remarkably alleviate the dissolution of polysulfides, and greatly enhance the conversion kinetics between the polysulfides and Li 2 S 2 /Li 2 S in the charge/discharge processes. The sulfur electrode dual-functionalized with biochar and CoO nanoparticles exhibits excellent electrochemical performance, including high initial discharge specific capacity of 930.5 mAh g−1 and low capacity decay rate of 0.069 % per cycle during 800 cycles at 1C rate. It is particularly interesting that the CoO nanoparticles distinctively enhance the Li+ diffusion during the charge process, endowing the material with excellent high-rate charging performance. This could be beneficial for the development of Li-S batteries with fast charging feature. [ABSTRACT FROM AUTHOR]

Polymeric binders stabilize lithium–sulfur (Li–S) batteries by suppressing the shuttle of lithium polysulfide (LiPS) and volume variation, but the dosage of state‐of‐the‐art binders in sulfur cathodes (≈20 wt%) hinders the electron/ion transfer and decreases the cell‐specific density. Here, a wood‐inspired lignin binder is developed after modification with amino acids for practical Li–S batteries at ultra‐low low dosage (2 wt%). Benefiting from strong and balanced adhesions with active/conductive/current collector materials, robust mechanical properties, and super LiPS anchoring capability, the Li–S cell delivers an initial discharge capacity of 864 mAh g−1 at 0.5 C and can readily operate 1000 cycles. Moreover, the pouch cell with high mass loading (4.75 mg cm−2) also delivers a high energy density of 484 Wh kg−1. This work provides important guidance in binder design for the sulfur cathode and paves a new way for the practical application of Li–S batteries. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries are one of the most promising next-generation batteries due to their ultra-high theoretical energy density and the abundance of sulfur. Organic sulfur cathodes have been extensively studied for their advantages such as no shuttle effect and no self-discharge. In this review, we classify organic sulfur into three categories: traditional sulfurized polyacrylonitrile, conductive polymer-based organosulfur, small molecule organic sulfur, and high-sulfur-content polymers, and summarize their applications in Li–S batteries. Some concepts for designing organosulfur cathodes and their directions are presented. • SPAN applications and modification strategies in lithium-sulfur batteries. • Conductive polymers in lithium-sulfur batteries. • Small molecule organic sulfur in lithium-sulfur batteries. • Some advances in high sulfur content polymers. [ABSTRACT FROM AUTHOR]

Physicochemical confinement and catalytic conversion of lithium polysulfides (LiPSs) are crucial to suppress the shuttle effect and enhance the redox kinetics of lithium‐sulfur (Li‐S) batteries. In this study, a NH4Cl‐assisted pyrolysis strategy is developed to fabricate highly mesoporous N‐rich carbon (designed as NC(p)) featuring thin outer shells and porous inner networks, on which single‐Ni atoms are anchored to form an excellent sulfur host (designed as Ni‐NC(p)) for Li‐S batteries. During pyrolysis, the pyrolytic HCl from confined NH4Cl within ZIF‐8 will in situ etch ZIF‐8 to produce rich mesoporous in the carbonized product NC(p). The mesoporous Ni‐NC(p) enables favorable electron/ion transfer, high sulfur loading, and effective confinement of LiPSs, while the catalytic effect of single‐Ni species enhances the redox kinetics of LiPSs. As a result, the sulfur cathode based on the Ni‐NC(p) host delivers obviously improved Li‐S battery performance with high specific capacity, good rate capability, and cycling stability. [ABSTRACT FROM AUTHOR]

The lithium–sulphur battery is a promising system for next‐generation energy storage because of its high energy density and the abundant supply of sulphur. In this study, Magnéli phase Ti4O7 nanotube arrays (NTA) were grown on titanium nitride mesh substrates via anodization of titanium mesh followed by high‐temperature reduction under a hydrogen atmosphere. When prepared into a composite material with sulphur via electrodeposition, Ti4O7 NTA provides sulphur with high electronic conductivity and strong polysulphide chemisorption during battery operation. The structure of NTA allows sufficient access of incorporated sulphur to the liquid electrolyte and supports high sulphur loadings per unit area of the electrode. The application of an additional layer of conductive carbon coating to confine electrodeposited sulphur inside the NTA further improved the cell cycling performance. Under sulphur loadings of around 2.0 mg/cm2, high values of specific capacity (1604 mAh/g at a 1/20 C rate), ultra‐low capacity decay rate (0.03% per cycle for 1800 cycles), and versatile rate capability (660 mAh/g at 2 C and 500 mAh/g at 4 C) were achieved. Under high sulphur loadings of around 5.0 mg/cm2, stable cycling (decay rate below 0.10% per cycle) and high areal capacity (4.97 mAh/cm2) were attained. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries are a promising electrochemical energy storage device due to their low cost, high energy density, and excellent sustainability, making them superior to many commercial lithium-ion batteries. Despite the great road to market, Li-S batteries still suffer from low practical energy density, which is intimately related to fundamental scientific and technological issues of sulfur cathodes. As a non-negligible parameter in sulfur cathodes, the compaction density plays a crucial role in the energy density of Li-S batteries. Herein, the effect of compaction density of sulfur/carbon cathodes on the electrochemical performance of Li-S batteries is investigated. It is demonstrated that sulfur/carbon cathodes with an optimized compaction density of 1.2 g cm−3 not only can guarantee the good contact of active materials, but can also ensure the rational dosage of electrolyte, thereby increasing the sulfur utilization as well as reducing the dissolution of polysulfide into the electrolyte. As a result, the pouch cells paired with the sulfur/carbon cathode and Li metal anode deliver superior specific capacity and remarkable cycling performance, which is attributable to the better contact between particles and the faster redox kinetics. This work reveals the contribution of the compaction density of the sulfur cathode to the electrochemical performance of the Li-S battery, providing an instructive paradigm for the rational design of an advanced sulfur cathode for large-scale commercialized Li-S pouch cells. [ABSTRACT FROM AUTHOR]

• A novel catalytic process for the disproportionation of dissolved polysulfides was discovered. • A pseudo-8-electron sulfur redox reaction mechanism was postulated. • The presence of dissolved polysulfides in the electrolyte was significantly reduced. • Efforts to mitigate the polysulfide shuttle phenomenon were successful. A catalytic pseudo-8-electron redox reaction of sulfur is achieved by facilitating the disproportionation of high-order polysulfide ions in a Li-Sulfur battery. Electrochemically generated polysulfide ions (S x 2-, where 3 < x < 7) undergo rapid disproportionation into elemental sulfur (S 8) and Li 2 S 2 , catalyzed by a bifunctional carbon host/catalyst. The overall catalytic redox reaction at the sulfur cathode is represented as S 8 + 8 L i + + 8 e ⇌ 4 L i 2 S 2. In contrast to physical or chemical confinement methods for polysulfide ions, this approach remediates the shuttle effect by swiftly converting soluble polysulfides in the electrolyte to elemental sulfur and insoluble Li 2 S 2 within the cathode matrix. As a result, the adverse chemical interaction between dissolved polysulfides and the Li anode is mitigated. [ABSTRACT FROM AUTHOR]

• An amorphous bimetallic MOF material with coordination deficiency was designed. • The resultant aFeNi-MOF with abundant defects and active sites endows higher adsorbability and catalytic activity. • This work provides a facile and novel amorphization method for the design of separator modifier in Li-S batteries. Severe polysulfide dissolution and shuttling during charging and discharging are the main challenges hindering the practical application of lithium-sulfur (Li-S) batteries. Constructing functional separators is considered as an economical and convenient way to suppress the shuttle effect and improve the kinetics of Li-S chemistry. In this work, partially ligand-deficient amorphous bimetallic MOF material (aFeNi-MOF) is designed via a ligand competition strategy and employed as a separator modifier. The aFeNi-MOF not only promotes the rapid transportation of ions, but also enhances the chemisorption and catalytic capability on sulfur species, enabling accelerated redox kinetics and polysulfide trapping in Li-S batteries. Consequently, the assembled coin cell using aFeNi-MOF-modified separator delivered a high reversible capacity of 931.1 mAh/g at 1C, a long cycle life of more than 500 cycles and a low capacity decay of 0.084 % per cycle. Meanwhile, the areal capacity of 3.70 mAh cm−2 can be achieved under a high sulfur loading of 4.5 mg cm−2 and low electrolyte usage, meeting the requirement of areal capacity for commercial applications of Li-S batteries. [ABSTRACT FROM AUTHOR]

Sluggish kinetics in thick cathode with high sulfur (S) loading will lead to low active material utilization and fast capacity decay, thus hampering the practical applications of Li–S batteries. To tackle such issue, a slightly thickness-dependent cathode of activated carbon (AC)-S/single-walled carbon nanotube (SWNT)@SWNT with fast reaction kinetics is constructed via continuously printing core-sheath filaments. Such micro-filaments are composed of vertically aligned "thin AC-S/SWNT" in core layer and porous SWNT-strengthened shell layer, which constructs an appealing well-interconnected porous 3D architecture ensuring fast ion/electron/mass transport throughout the whole printed matrix, effectively expediting electrochemical kinetics even under a high S loading. Moreover, the SWNTs located in shell layer and intercalated in-between AC-S phase in core layer crosslink well for acting as the functional interlayer to suppress polysulfide shuttling, thereby enabling high S utilization. As a result, the 3D-printed thick AC-S/SWNT@SWNT cathode delivers outstanding gravimetric/areal capacity (752 mAh g−1/6.41 mAh cm−2 at 0.5C) and cycling performance under high S loading of 8.6 mg cm−2. Tuning rational cathode architecture with high S loading remains a significant challenge for Li–S battery. Here we demonstrate for the first time the capability of an extrusion-based core-sheath 3D printing for consistently constructing highly S-loaded cathode with well-interconnected aligned channels and crosslinked SWNT network, which facilitates high S utilization and fast reaction kinetics at large electrode thickness, and meanwhile suppresses polysulfide shuttling and volume expansion, thereby enabling a thick cathode with outstanding gravimetric/areal capacity and cycling performance. [Display omitted] • Core-sheath cathode with high S loading is constructed via 3D printing strategy. • Cathode features well-interconnected aligned channels and crosslinked SWNT network. • Unique structure favors S utilization and fast reaction kinetics at large thickness. • Thick cathode delivers eminent gravimetric/areal capacity and cycling performance. [ABSTRACT FROM AUTHOR]

A better understanding of the redox process of lithium polysulfide (LPS) on carbon surfaces is helpful for designing Li/S batteries with better performance. The "shuttle mechanism" can explain the low coulomb efficiency and self-discharge of a Li/S battery, but it cannot explain the fact that battery performance is strongly affected by electrolyte volume and sulfur load. This paper aims to reveal the main redox process of LPS on the surface of carbon by examining the cathodic behavior with different electrolyte volume and sulfur load. Scanning electron microscopy (SEM) images and impedance spectra of the cathode before and after the first discharge were compared, and it was found that the discharge process is the continuous dissolution of sulfur composited with carbon into the electrolyte to form LPS. At the same time, LPS re-precipitates sulfur on the surface of the cathode through a disproportionation reaction to form a solid film. Cyclic voltammetry (CV) curves showed that the solid film passivates the electrode, and the electrode is activated only when the potential is swept negatively and Li2S is generated. When a lean electrolyte is used, there is fluctuation in the CV curves, which proves that the dissolution-reprecipitation of sulfur is the main process of the cathode. The discharge–charge curves of cathodes with different sulfur load were compared, and it was found that there is wavy fluctuation in the discharge curve when the sulfur load increases, which proves again that the sulfur reaction dominates the electrode process. [ABSTRACT FROM AUTHOR]

Summary: Ni nanomaterials exhibit excellent adsorption and catalytic ability in the redox reaction of Li‐S batteries. Hence, Ni nanodots are embedded in the micropores and mesopores of commercial Ketjen black (KB) to obtain Ni/KB composite nanomaterials by an in situ preparation method with low cost and high yield. The prepared Ni nanodots with 5 to 30 nm diameter act as the active sites in KB matrix and enhance the intrinsic activity; they can not only adsorb lithium polysulfides (LiPSs) by the Ni‐S bond but also promote the conversion rate of LiPSs. Consequently, with 3.1 mg cm−2 S loading on positive electrode, the initial discharge capacity of Ni/KB/S electrode at 0.05 C reaches 1253 mAh g−1 and the initial discharge capacity at 0.5 C reaches 818.4 mAh g−1, with the stable cycle exceeding over 500 cycles. [ABSTRACT FROM AUTHOR]

The design of sulfur hosts with polar, sulfurphilic, and conductive network is critical to lithium-sulfur (Li-S) batteries whose potential applications are greatly limited by the lithium polysulfide shuttle effect. Mxenes, possessing layered-stacked structures and high electrical conductivities, have a great potential in sulfur hosts. Herein, sulfur nanoparticles uniformly decorated on titanium carbide Mxene (S@Ti3C2Tx Mxene) are synthesized via a hydrothermal method and then utilized as a cathode for lithium-sulfur batteries. This unique architecture could accommodate sulfur nanoparticles expansion during cycling, suppress the shuttling of lithium polysulfide, and enhance electronical conductivity. Consequently, the S@Mxene with a high areal sulfur loading (∼4.0 mg cm−2) exhibits a high capacity (1477.2 mAh g−1) and a low capacity loss per cycle of 0.18% after 100 cycles at 0.2 C. This work may shed lights on the development of high performance sulfur-based cathode materials for Li-S batteries.

The design strategies for the catalytic materials, including defect engineering, morphology engineering, and catalyst compositing, facilitate sulfur supercooling, fast charge transfer, thiosulfate generation, disulfide bond cleavage, tuneable Li 2 S growth, and Li 2 S decomposition enhancement, thereby addressing the challenges of the LSB in terms of high energy barrier and low conductivity of S 8 and Li 2 S, severe polysulfide shuttling and high polarization of Li 2 S 2 /Li 2 S deposition. [Display omitted] Lithium-sulfur batteries (LSBs) are attractive candidates for post-lithium-ion battery technologies because of their ultrahigh theoretical energy density and low cost of active cathode materials. However, the commercialization of LSBs remains extremely challenging primarily due to poor cycling performance and safety concerns, which are inherently caused by low conductivity of S 8 and Li 2 S, severe polysulfide shuttling, and high polarization by solid Li 2 S 2 /Li 2 S deposition. Catalytic materials could facilitate the large-scale practical application of LSBs by overcoming all these challenges. In this review, we investigate the sulfur species evolution in LSBs and explore the roles of catalytic materials in charge/discharge processes, highlighting the catalysis of solid S 8 to liquid polysulfides and solid Li 2 S 2 to Li 2 S. Furthermore, we offer systematic strategies from atomic to macro levels, including defect engineering, morphology engineering and catalyst compositing, to enhance catalysis efficiency in terms of sulfur supercooling, fast charge transfer, thiosulfate generation, disulfide bond cleavage, tuneable Li 2 S growth and Li 2 S decomposition enhancement. The design and availability of the proposed catalytic materials will further advance LSB technology from coin cells and pouch cells to the subsequent commercialization scale. [ABSTRACT FROM AUTHOR]

• VN/Mo 2 C heterointerfaces nanoparticles are monodispersed on N-doped carbon nanosheets. • Mo 2 C and VN synergistically promote the diffusion and conversion of polysulfides. • The functional separator also has excellent protective effect on the lithium anode. • The modified separator exhibits superb electrochemical performance in Li-S batteries. Lithium-sulfur (Li-S) battery is deemed as one of the optimal next-generation energy storage devices due to its low cost and high energy density. However, the shuttle effect of lithium polysulfide (LiPS), sluggish reaction kinetics, and fatal Li-dendrite growth hinder its practical applications. In this work, a bifunctional nitrogen-doped carbon nanosheet conductive framework embedded with VN-Mo 2 C heterointerfaces (VN/Mo 2 C@CNS) is reported as a separator modifier for both sulfur cathode and lithium anode. The VN/Mo 2 C@CNS can offer a synergistic effect of strong surface affinity, good catalytic activity, and small diffusion barrier to accelerate the conversion of polysulfides, which was confirmed by in-situ Raman and theoretical calculation. Moreover, the composite has good lithiophilicity, thus inhibiting the formation of dendrites and achieving uniform lithium deposition. Benefiting from the above merits, the Li-S cells with VN/Mo 2 C@CNS separator obtain desirable rate performance (687 mAh g−1 at 4 C), long cycle life of 1000 cycles (0.042 % capacity attenuation per cycle at 1 C), high areal capacity of 4.2 mAh cm−2 (under a high sulfur loading of 5.6 mg cm−2), and stable performance in protecting the Li anode (at 5 mA cm−2 for 1000 h). This work highlights a novel strategy for facilely designing heterostructures, offering valuable insights to tackle sulfur cathode and lithium anode challenges simultaneously for longevous Li-S batteries. [ABSTRACT FROM AUTHOR]

The notorious polysulfides shuttling and slow redox reaction kinetics largely limit the Li–S battery commercial application as an effective energy storage system. In this report, Mn/N catalysts were co-doped on a high specific surface area reduced graphene oxide (RGO) scaffold by a simple formamide media-assisted method to develop the sulfur holding material for Li–S battery. The N-doped RGO with conductive layer structure not only facilitates the ion and electron transfer, but also provides superb reservoir space for sulfur volume expansion and intermediate polysulfides. Moreover, the introduction of Mn metal catalysts both paly the roles of chemical trappers and electrocatalysts to chemically anchor the polysulfides and accelerate the redox kinetics. It is a promising holding material to improve the reutilization of the polysulfides and suppression of the shuttle effect in lithium-sulfur batteries. As a result, the high initial discharge capacity for the Mn-NG modified Li–S battery is about 1124.7 mAh g−1 at 0.2 C, which can still reach to 914.3 mAh g−1 after 100 cycles, with a retention rate up to 81%. We believe that our method offers a significant approach to prepare multi-functional sulfur hosts for high performance Li–S batteries. [Display omitted] • Mn/N-G is fabricated by formamide media-assisted method to use as S holding material. • Mn/N-G proves ion and electron transfer tube and sulfur volume expansion space. • Mn catalysts as the catalysts and anchors accelerate the kinetics of redox reaction. [ABSTRACT FROM AUTHOR]

Synthesis of hybrid architectures for sulfur host materials has been certificated as an efficient way to enhance the performances of lithium-sulfur (Li–S) batteries owing to the generated synergetic effects from each component. However, it remains challenging to construct hybrid nanostructures with reasonable structure and rational composition to achieve high-performance of Li–S batteries. Here, a coordinated nanostructure constituted of the Mo 2 C nanoparticles embedded in the micro-flowered high content N-doped (11.73 at.%) carbon substrate (Mo 2 C@NC) is synthesized via using protonated g-C 3 N 4 as the template, which is used as the sulfur host for Li–S batteries. Owing to the physical entrapment from the porous carbon substrate with special micro-flower morphology, and the synergistic chemisorption from pyridine N sites and polar Mo 2 C nanoparticles, the as-prepared Mo 2 C@NC can afford a high content of sulfur loading and enables fast/reliable sulfur electrochemistry. Given these, the Mo 2 C@NC based cathode with a high sulfur content of 76% delivers a high initial discharge capacity of 1403.7 mAh g−1 at 0.1 C. Even at a high rate of 2.0 C, it still shows desirable electrochemical performances with an initial capacity of 910.6 mAh g−1 and superb cycling stability with an average capacity decay rate of only 0.001% per cycle over 500 cycles. Moreover, upon a high sulfur loading of 5.5 mg cm −2, the Mo 2 C@NC/S cathode can still maintain decent sulfur related electrochemistry and achieves a high areal capacity of 5.56 mAh cm−2 with excellent stability. It is expected this work provides a new perspective to the rational design of conductive and polar material that suitable for high-efficiency and long-lasting Li–S batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Lithium-Sulfur (Li-S) batteries have become an incredible challenge for the approaching age of high-vitality stockpiling gadgets. Nevertheless, one of the main specialized issues emerging in Li-S batteries is the polysulfide disintegration among electrodes and striking capacity limit. Here, sieved sepiolite (200 mesh sieve) has been favored as an added substance material to counter the above difficulties in the sulfur battery. The zinc oxide nanoparticles were prepared by co-precipitation method and a Sulfur/post-treated sieved Sepiolite/Zinc Oxide (S/PTSp/ZnO) nanocomposite was prepared by warmth treatment. The prepared composite was described by XRD, FTIR, RAMAN, SEM with EDAX, TEM, XPS, TG, and Electrochemical analysis. The S/PTSp/ZnO composite cathode exhibited an initial discharge capacity of 1,391 mAhg−1 and attained a stable capacity of 765 mAhg−1 at 200 cycles. In conclusion, Li-S batteries can be relied upon to capably build up the utilization of sulfur and limit the disintegration of polysulfides into an electrolyte.

Derived from low-cost biomass chitin with hierarchical N-involving molecular structures, a novel renewable N-doping carbonaceous host material (denoted as C-NC) for S cathode in Li-S batteries with 3D network-like structures was fabricated via a facile dissolution and carbonization approach. When incorporated with a small amount of graphene (GN) and g-C 3 N 4 , the final products of C-NC/GN/g-C 3 N 4 hybrids maintain the 3D interconnected network-like morphology assembled by 2D ultrathin graphene-like sheets. Meanwhile, the hybrids synergize the advantages of the graphene with high conductivity to facilitate fast electron transfer, the g-C 3 N 4 with efficient chemical absorptivity for intermediate polysulfides to inhibit the unfavorable dissolution, as well as the 3D network frameworks of C-NC with high surface area and macro/mesoporous features to offer rapid ion diffusion channels and adequate electrolyte infiltration and mitigate the structural changes of S cathode during cycling. When loading with elemental S, the fabricated S@C-NC/GN/g-C 3 N 4 cathode shows superior high-rate capability and remarkable cycling performance, which maintains a high reversible capacity of ∼1130 mA h g−1 after 500 consecutive electrochemical cycles. This renewable biomass-based cathode construction strategy offers a low-cost promising approach to design high-rate and ultralong-lifespan Li-S batteries. Image 1 • Novel renewable sulfur host material was derived from biomass chitin. • The products synergize the advantages of N-doped carbon, g-C 3 N 4 and graphene. • The obtained network-like 3D architecture is assembled by ultrathin 2D nanosheets. • The fabricated S cathode exhibits long lifespan and high rate capability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A general synthesis strategy of MOF/PAN grown in situ was designed. • Nitrogen-doped carbon nanofibers were used as independent cathodes. • MOF-derived bimetallic nanoparticles collaboratively catalyze nucleation of Li 2 S. • Porous carbon nanofibers limit the volume expansion of sulfur cathodes. In the electrochemical study of lithium-sulfur (Li-S) batteries, the slow kinetics of the sulfur reduction reaction (SRR) leading to severe shuttle effect of polysulfides remains a major challenge. Catalysts with bimetallic nanoparticles have higher adsorption affinity for lithium polysulfides and hold great potential in improving reaction kinetics. In this study, a nitrogen-doped carbon nanofiber carrier was prepared using high-voltage electrospinning technology, and through in-situ growth and high-temperature pyrolysis process, the carrier material was uniformly loaded with active sites of NiCo bimetallic nanoparticles derived from Metal-organic framework (MOF), aiming to improve the kinetics of sulfur oxidation and reduction and reduce the severe shuttle effect of soluble polysulfides. At the same time, polymethyl methacrylate was added to adjust the pore structure of the carbon nanofibers to form an ideal independent sulfur cathode porous conductive carbon network for rapid ion transport to prevent Li 2 S deposition and alleviate the volume change during lithiation/delithiation process. Experimental results show that the synergistic catalytic effect of bimetallic nanoparticles can not only rapidly anchor lithium polysulfides throughout the entire reaction process of Li-S batteries, but also reduce the resistance during the reaction process, accelerating the conversion of lithium polysulfides to Li 2 S deposition. It demonstrates outstanding electrochemical performance, with a first-cycle discharge specific capacity as high as 1431.7 mAh g−1 at a 0.2 C rate, and a Coulombic efficiency of 96%. After 500 cycles, its capacity still maintains at 628.5 mAh g−1, with a decay rate of only 0.11% per cycle. This study provides a feasible insight into the synergistic catalysis of MOF-derived metal nanoparticles, which has important guiding significance and potential impact on the catalysis of Li-S batteries by bimetallic nanoparticles with an independent sulfur cathode structure, and is expected to accelerate the industrialization process of Li-S batteries. [ABSTRACT FROM AUTHOR]

The sulfur-activated Ketjen black nanostructure (S@KB), as the cathode in lithium-sulfur (Li-S) battery, was synthesized using the sulfur-amine chemistry technique. The nano-sized sulfur particles expedite the electrical conductivity, and strengthen the sulfur utilization. Moreover, the sulfur nanoparticles compensate for its massive volume expansion driven by the lithiation process. The activation of KB can cultivate the electrochemical properties of the cathodic composition for protracted cycling by intensifying the available surface area. The sulfur mass loading was about 1 mg cm−2. The premier specific capacity was acquired 1190.63 mAh g−1 at 0.1 C, which was stabilized to 671.32 mAh g−1 after 200 cycles. The accomplished characterizations substantiate the suitable incorporation of sulfur into the activated KB (AKB) structure and the splendid interaction between them. It was educed that the S@KB cathode can relieve the penetration of polysulfides toward the anode and, as a result subdue the shuttle effect. It was determined a notable reversible capacity of 1002.81 mAh g−1 after 40 cycles at varied current rates. [Display omitted] [ABSTRACT FROM AUTHOR]

In order to effectively alleviate the shuttle effect in lithium-sulfur batteries (LSBs), cherry blossom-derived micron carbon sheets loaded with a small amount of Co-based nano-particles are synthesized in this work. After the thermal decomposition of ZIF-67, the composite shows a high specific surface area (2768.2 m² g−1) and pore volume (1.63 cm³ g−1), which can enhance the physical adsorption of polysulfides. Moreover, the Co-N and Co nano-particles obtained by ZIF-67 have strong catalytic and polar adsorption abilities. Not only can they accelerate the electrochemical reaction, but also effectively inhibit the shuttle effect of polysulfides, which in turn improves the electrochemical performance of lithium-sulfur batteries. Thus, the initial discharge capacity of the Co-PB@S electrodes reached 933 mAh g−1, with a remaining capacity of 550 mAh g−1 after 500 cycles at 0.5 C. This work may provide a practical way for the application of LSBs and the field of electrocatalysis. [Display omitted] [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (rGO) covered sulfur loaded on carbon fibers have been fabricated by combinations of melt-flow and electrochemical coverage strategies. rGO layers can serve as conductive composite and protective layer to improve the specific capacity and cycling stability of S/carbon fiber based LSB. [Display omitted] • Carbon fibers and rGO as conductive components supply double transporting paths of electrons. • rGO as blocking layers inhibits the soluble sulfur diffusing into electrolyte. • rGO layers as another redepositing places increase the utilization of sulfur. To improve the electrochemical performance of Li-S batteries, a cathodic material (rGO 150 /S/CF-75) was fabricated for Li-S batteries by adopting a melt-flow method to load sulfur on biomass-derived carbon fibers, then the reduced graphene oxide was electrochemically covered on the outside surface of the sulfur. The coverage of reduced graphite oxide layers endows the performance of S/CF-75 multiple improvements. The specific capacity of rGO 150 /S/CF-75 cathode delivers a specific capacity of 1451.4 mAh g−1 at 0.1 A g−1. The specific capacity of rGO 150 /S/CF-75 cathode can still maintain 537.3 mAh g−1 after 1000 cycles at 5 A g−1 (109 % capacity retention). The excellent performance of rGO 150 /S/CF-75 cathode is benefit from not only the conductive paths of reduced graphene oxide layers and protective function of reduced graphene oxide layers inhibiting that the soluble sulfur diffuse into bulk electrolyte, but also the redistribution of sulfur on conductive carbon components during the cycling process. [ABSTRACT FROM AUTHOR]

• A sulfur cathode was fabricated by covalently bonding sulfur with UiO-66(SH) 2 @CNT. • The cathode can inhibit the shuttle effect and accelerate polysulfide conversion. • The assembled Li-S cells exhibit excellent electrochemical performance. The shuttle effect and sluggish reaction kinetics have hindered the practical application of lithium-sulfur (Li-S) batteries. In this work, a thiol-rich MOF was in situ synthesized on carbon nanotube (CNT) and sulfur was covalently connected to this composite to form a MOF-sulfur copolymer (S-UiO-66(SH) 2 @CNT). Benefiting from the strong covalent interaction between thiol groups and sulfur, the resultant cathode can retard the shuttle effect and simultaneously strengthen the redox kinetics. As a result, the S-UiO-66(SH) 2 @CNT cathode exhibits a higher capacity retention of 93.27 % at 0.5C during 200 cycles than that of the physically mixed S/UiO-66@CNT cathode (64.94 %). This work will provide insight into the design of advanced MOF-based cathodes for Li-S batteries. [ABSTRACT FROM AUTHOR]

Lithium sulfur batteries (LSBs) have been recognized as one of the most promising next generation rechargeable batteries due to their high specific capacity and energy density. However, the practical application of LSBs is hindered by the low sulfur utilization due to the insulation nature of sulfur, and by the serious capacity fading of sulfur cathode arising from "shuttle effect" of polysulfides during the discharge-charge process. Herein we design and fabricate a 3D structured sulfur cathode based on Li 4 Ti 5 O 12 nanowire array (LTOWA) to address these issues. In this cathode, the 3D nanowire array structure can facilitate electron transport and provide satisfactory electrochemically active surface where electron and Li ions can meet with the sulfur for fast conversion reaction, ensuring the high sulfur utilization of cathode even with a large areal sulfur content; in addition, we also show, by X-ray photoelectron spectroscopic and electrochemical analyses, that LTO can immobilize the migrating polysulfide intermediates via Ti–S bond more effectively than the conventionally used TiO 2 (TO), which adsorbs polysulfide mainly through O–S bond. As a result, the LTOWA/sulfur composite cathode with a high sulfur loading (4 mg cm−2) shows a high utilization of sulfur (1100 mAh g−1 at 0.02C) and excellent cycle life (80% capacity retention after 300 cycles at 1C, namely 0.06% per cycle). Our work suggests that the performance of polar oxide/sulfur composite cathodes can be further improved by the synergistic effect of more effective chemical bonds and architectural design. Nanowire array structure can optimize cathode kinetics and Li 4 Ti 5 O 12 (LTO) can immobilize polysufides via Ti–S bond (which is more effective than O–S bond). Therefore, the sulfur cathode based on LTO nanowire array structure exhibits superior sulfur utilization and excellent cycle life even with 4 mg cm−2 sulfur loading. Image 1 • A binder-free sulfur cathode based on the Li 4 Ti 5 O 12 nanowire array (LTOWA) is synthesized. • Li 4 Ti 5 O 12 can immobilize polysulfides via Ti-S bond, more effective than O-S bond. • Nanowire array can enhance sulfur utilization and rate performance of cathode even with a large areal sulfur content. • LTOWA/sulfur cathode with 4 mg cm−2 sulfur loading shows a high utilization of sulfur and excellent cycle life. [ABSTRACT FROM AUTHOR]

Rather than preventing the dissolution and diffusion of polysulfides, promoting polysulfide conversion through improved polysulfide redox is another promising strategy to suppress the dissolution of polysulfides and enhance the cycle life of sulfur cathodes. We demonstrated that VO 2 -rGO not only facilities liquid-involving polysulfide redox (Li 2 S 8 →Li 2 S 6 →Li 2 S 4), but also promotes the effective decompositions of lithium sulfide (Li 2 S). As evidenced by the visual experiments and DFT calculation, VO 2 -rGO has strong affinity for polysulfides species. With sulfur loading of 2.15 mg cm−2 and sulfur content of 76 wt%, the reversible capacity retained at 896 mAh g−1 after 200 cycles. • Highly porous structure is generated after VO 2 nanorods are embedded in rGO. • VO 2 can efficiently promote the phase transformation of polysulfide. • This electrode can last for 200 cycles with reversible capacity of 896 mAh g−1. [ABSTRACT FROM AUTHOR]

A polysulfides-adsorptive and conductive host for sulfur (S) cathode is highly required for Li S batteries. Herein, we present a unique ternary S/C@SnO 2 composite consisting of a 3D tubular core-shell structure in which a carbon matrix as the core is coated by a porous SnO 2 shell. Sulfur is coated on carbon inside the tubes. The S/C@SnO 2 exhibits a good electrochemical performance including a stable capacity of 730 mAh g−1 after cycling for 500 times at 0.1C, along with a fading rate as low as 0.07% per cycle. The capacities recover well during two rounds of rate-performance measurements, exhibiting a recovery rate exceeding 96.3%. The composite also delivers stable capacities when cycling at different charge vs. discharge rates. The polysulfides-adsorptive capability of the SnO 2 shell as an efficient protection shield is demonstrated through density functional theory calculation, which confirms a high surface-energy of SnO 2 towards Li 2 S 4 , Li 2 S 6 , and Li 2 S 8. The porous carbon matrix inside the SnO 2 tubes provides a good conductivity for sulfur and spaces for the volume-change of sulfur. Those features of the ternary S/C@SnO 2 enable it to be a promising cathode candidate for Li S batteries. Unlabelled Image • A unique ternary sulfur/carbon@tin dioxide composite is reported. • Polysulfides-adsorptive shell and conductive core are achieved. • Ternary composite exhibits a high performance for Li S battery. • First-principle modeling confirms a high surface energy of SnO 2 shell. [ABSTRACT FROM AUTHOR]

• PMP host is a hierarchically structural functional Janus composite. • PMP host is prepared using a simple LBS method. • PMP-S cathode can immobilize lithium polysulfides physically and chemically. • PMP-S cathode achieves long cyclic life and excellent rate performance. A facile and effective strategy is proposed to fabricate high-performance Li-S battery cathodes with a hierarchically structural Janus host composed of multiwall carbon nanotubes (MWCNTs) and polyethyleneimine (PEI). The MWCNTs act as conductive skeleton for physical confinement of S and the PEI can chemically immobilize the S/lithium polysulfides. Benefiting from synergistic effects of the multifunctional host, the cathode can load with high S and simultaneously achieves excellent reversible capacity and outstanding rate performance. For instance, the capacity remains around 500 mAh g−1 even after 350 cycles at 0.2 A g−1 with a capacity decay of only 0.12% per cycle. Even at a higher rate current of 1 A g−1, the per cycle capacity decay is only 0.1% within 160 cycles. [ABSTRACT FROM AUTHOR]

Although Li-ion batteries have revitalized the energy storage platform, higher energy density for long-range applications is still a challenge. Beyond Li-ion, Li-S battery could be one of the most promising technologies, but challenges such as lithium polysulfide shuttling, sluggish reaction kinetics and low areal sulfur loading (<2.0 mg cm−2) remain. Herein, we report a multifunctional electrode composite consists of conducting polymer-carbon complex where the sulfur loading can reach as high as ∼75 wt %. Owing to high electrical conductivity and inherent heteroatom compositions of conductive polymers, composite electrodes are capable of suppressing polysulfide shuttling and enhance reaction kinetics via catalysis. As a result, these composite electrodes deliver outstanding electrochemical performance with the specific capacity of ∼1100 mAhg−1 for more than 100 cycles. A one-pot and straightforward procedure at ambient conditions to prepare these composite electrodes are demonstrated. A multifunctional electrode composite consists of conducting polymer-carbon complex where the sulfur loading can reach as high as ∼75 wt % is reported. Owing to high conductivity and original heteroatom compositions of conductive polymers, composite electrodes are capable of suppressing polysulfide shuttling while enhancing the reaction kinetics via catalysis. Image 1 [ABSTRACT FROM AUTHOR]

Free‐standing carbon nanotube (CNT) frameworks have been found to be highly effective in increasing sulfur loading and energy density of lithium–sulfur (Li–S) batteries. This owes to their ability to accommodate a large amount of sulfur in their interspaces. Also, this solution does require neither a binder nor a current collector. As a drawback, the application of free‐standing CNT frameworks suffers from the abundance of their inherent macroporosities, as these promote the diffusion of polysulfides. In this work, we address this issue by incorporating disordered mesoporous carbon (DMC), as a polysulfide reservoir, into a CNT matrix to form CNT–DMC hybrid film. We apply facile hot‐pressing to incorporate sulfur into the composite electrode. Furthermore, we determine the electrochemical performances of CNT–DMC/sulfur (S) cathode by a galvanostatic method. We find that the CNT–DMC/S cathode exhibits a high initial capacity of 1032 mAh/g at 0.25 C and a superior capacity retention of 92% after 100 cycles, compared to sulfur‐impregnated CNT cathode. We attribute these enhancements to the efficient polysulfide absorption ability of DMC. This novel approach bears a high potential for the development of high‐performance Li–S batteries with flexible sulfur cathodes. [ABSTRACT FROM AUTHOR]

In this study, cetyltrimethylammonium bromide (CTAB)-modified separator is developed by using a simple and facile method for lithium-sulfur (Li-S) batteries. CTAB is coated on only one side of separator using a doctor blade. The coated CTAB on the separator improves wettability between separator and electrolyte and ionic conductivity of separator. In addition, CTAB also inhibits the migration of dissolved polysulfides to the anode side. These phenomena improve the electrochemical properties of Li-S batteries using CTAB-coated separators. Cells using the CTAB-coated separator exhibit an initial capacity of 1136 mAh g−1 at 0.2 C-rate. In addition, they can maintain a higher capacity (765 mAh g−1) and capacity retention rate (67.3%) after 150 cycles as compared to pristine Li-S batteries (549 mAh g−1 and 48.5%, respectively). These results indicate that the CTAB-coated separator can enhance the performance of Li-S batteries.Graphical abstract: [ABSTRACT FROM AUTHOR]

The low sulfur utilization and notorious polysulfides shuttling of Li-S battery (LSBs) largely limit the practical implementation as an effective energy storage system. Herein, we designed a coaxial electrospinning process to prepare cobaltous selenide/carbon tube (CoSe 2 /CTs) with hollow tubular structures to hold sulfur activity for the cathode of LSBs. This CoSe 2 /CTs material with superior hollow tubular structures and high specific surface area is able to tolerate the sulfur volume expansion/contraction and make the intimate contact with sulfur at the micro level. Moreover, the uniformly dispersed CoSe 2 on the CTs both as catalysts and trappers can significantly facilitate the reaction kinetics in the LSBs and chemically immobilize lithium polysulfides. In order to optimize the CoSe 2 /CTs/S cathode, we investigated the effects of the Co concentration and carbon tube porosities on batteries performance to achieve the satisfactory discharge specific capacity and a long duration at a high current density. We believe that our method can provide a significant strategy to prepare Co-based cathodes and enhance the performance of LSBs. [Display omitted] • The Polar, catalytic, volume-tolerant CoSe 2 /CTs material is designed and prepared. • The CoSe 2 /CTs are prepared by coaxial electrospinning and in-suit selenylation. • CoSe 2 /CTs both as catalysts and trappers facilitate the reaction kinetics in LSBs. [ABSTRACT FROM AUTHOR]

A hierarchical porous carbon (HPC) structure was developed from the waste orange peel using KOH as an activating agent. In HPC, the carbon has interconnected hierarchical pores size of which lies between 2 nm and 5 μm. HPC/S composite was prepared by melt-diffusion method and analysed for electrochemical performance. HPC/S exhibits a high initial discharge capacity of 870 mAhg−1 at 0.2C and 734 mAhg−1 at 0.4C. The Carbon-black (CB)/Sulfur (S) composite was also prepared and characterized. A comparative study was done with the CB/S composite, which shows poor cyclability and a discharge capacity of 332 mAhg−1 at 0.2C rate considering 1C = 1672 mAhg−1. Sulfur confinement in the HPC structure leads to superior electrochemical performance of the HPC/S composite ensuring a promising cathode material. [Display omitted] • Hierarchical porous carbon (HPC) structure is synthesized by using KOH as an activating agent. • HPC/S composite is prepared by adopting the melt diffusion method. • HPC/S retains 25.5 % more sulfur, addressed as pore-confined sulfur. • Comparative study shows superior electrochemical performance of HPC/S than CB/S composite. [ABSTRACT FROM AUTHOR]

Shuttle effect and slow redox reactions in Li-S battery limit its commercial application. Herein, TiN nanotubes with N-doped carbon coating (TiN/N-C NT) were obtained via MoO 3 nanorod template-assistant hydrothermal method and followed by polydopamine coating and carbonization/nitriding. When used as sulfur host, the tubular structure buffers the volume change in lithiation process and shortens Li+ transfer route. Consequently, the TiN/N-C NT cathode exhibits a high capacity of 1010.3 mAh g−1 over 100 cycles at 0.1 A g−1. It provides a low capacity decay rate of 0.057 % per cycle over 500 cycles at a high current density of 1.0 A g−1. This study provides a promising method for preparing high-performance Li-S battery. • Special TiN nanotubes coated with N-doped carbon layer were developed. • It involves template-assistant hydrothermal method, PDA coating and carbonization/nitriding. • TiN/N-C nanotubes exhibit high stable capacity and superior rate performance. • High performance is due to thier hollow structure and strong LiPSs chemisorption. [ABSTRACT FROM AUTHOR]

• A water-based network binder combining robust mechanical property and strong affinity has been constructed. • LSO, rich in abundant strong polar bonds, can not only effectively adsorb polysulfides but also firmly connect TPG biopolymer chains. • An impressive long lifespan of 200 cycles at 0.2C has been achieved, under a high loading of 5.4 mg cm−2. To achieve practical high energy density of Li-S battery, it is crucial to construct high-loading sulfur electrodes. However, the poor mechanical stability and severe shuttle effect of high-loading sulfur cathodes during cycling limit the cycling stability. Herein, a mechanically robust network binder with strong affinity towards polysulfides has been designed to stabilize the high-loading sulfur electrode. Lithium polysilicate (LSO) possesses abundant strong polar Si-O and Si = O bonds, which not only can effectively adsorb polysulfides but also firmly connect tamarind polysaccharide gum (TPG) biopolymer chains. As a result, the c-LSO-TPG binder can efficiently maintain the integrity of high-loading sulfur cathode and suppress the polysulfide shuttling during cycling. In particular, under a high sulfur loading of 5.4 mg cm−2, the sulfur electrode can run 200 cycles steadily, delivering an areal capacity of 2.7 mAh cm−2. This provides a new avenue for the research and development of robust binders for high-loading and long-lifespan Li-S batteries. [ABSTRACT FROM AUTHOR]

• A novel polyaniline-coated Ni 3 N/S microflowers was developed. • Ni 3 N microflowers are prepared via hydrothermal reaction followed by a nitridation process. • Ni 3 N/S@PANI microflower cathode exhibit high stable capacity and superior rate performance. • High electrochemical performance is due to hierarchical structure of Ni 3 N and PANI coating. This paper presents novel polyaniline-coated Ni 3 N/S (Ni 3 N/S@PANI) microflowers as sulfur host for lithium–sulfur battery to solve the problems of cathode, such as poor electrical conductivity caused by sulfur and shuttle effect caused by multi-sulfide dissolution. Microflower-like Ni 3 N is synthesized using hydrothermal reaction followed by a nitridation procedure. The Ni 3 N/S@PANI microflowers are obtained by compounding the Ni 3 N microflowers with sulfur powder, followed by polyaniline coating. The as-prepared Ni 3 N/S@PANI microflowers exhibit the first capacity of 935 mAh/g at 0.5 A/g and retain 678 mAh/g after 200 cycles. The high electrochemical property is due mainly to the porous hierarchical structure of the Ni 3 N and the highly conductive polyaniline coating, which provide sufficient interspace to mitigate the volume expansion of sulfur and trap polysulfides, and inhibit the dissolution of polysulfides, respectively. [ABSTRACT FROM AUTHOR]

Here, we report a two-step synthesis of graphene/sulfur/carbon ternary composite with a multilayer structure. In this composite, ultrathin S layers are uniformly deposited on graphene nanosheets and covered by a thin layer of amorphous carbon derived from β-cyclodextrin on the surface. Such a unique microstructure, not only improves the electrical conductivity of sulfur, but also effectively inhibits the dissolution of polysulfides during charging/discharging processes. As a result, this ternary nanocomposite exhibits excellent electrochemical performance. It can deliver a high initial discharge and charge capacity of 1410 mAh·g−1 and 1370 mAh·g−1, respectively, and a capacity retention of 63.8% can be achieved after 100 cycles at 0.1 C (1 C = 1675 mA·g−1). A relatively high specific capacity of 450 mAh·g−1 can still be retained after 200 cycles at a high rate of 2 C. The synthesis process introduced here is simple and broadly applicable to the modification of sulfur cathode for better electrochemical performance.

Lithium-sulfur (Li-S) batteries are considered as one of the most promising energy storage systems. However, the commercial application of Li-S batteries with practical loading levels (>7 mg cm −2 ) still remains several obstacles, including low sulfur utilization, short lifespan, and poor rate property. Exploiting advanced multifunctional binders is an effective and straightforward approach to improve electrochemical performance and this method has the inherent advantage of not introducing additional weight and volume, which will undermine maximizing the cell energy density. Traditional PVDF binder fails to withstand mechanical instability of high-loading electrode; moreover, the binder possesses poor affinity for polysulfides, making it unsuitable for high-loading Li-S battery. Hence, designing rationally advanced binder systems is urgently required to fabricate high-loading sulfur electrodes. Although much effort has been devoted in this regard, practical binders for high-loading sulfur electrodes are still absent. To accelerate the development of such binder systems, we review the recent progress on the advanced binders in high-performance Li-S batteries. We discuss their functional mechanisms, summarize their desirable properties, and then provide perspective on the future development of advanced binders for practical Li-S batteries. [ABSTRACT FROM AUTHOR]

Carbon matrix (CM) derived from biomass is low cost and easily mass produced, showing great potential as sulfur host for lithium sulfur batteries. In this paper we report on a dihydrogen phosphate modified CM (PCM-650) prepared from luffa sponge ( luffa acutangula ) by phosphoric acid treatment. The phosphoric acid not only increases the surface area of the PCM-650, but also introduces dihydrogen phosphate onto PCM-650 (2.28 at% P). Sulfur impregnated (63.6 wt%) PCM-650/S, in comparison with samples with less dihydrogen phosphate LPCM-650/S, shows a significant performance improvement. XPS analysis is conducted for sulfur at different stages, including sulfur (undischarged), polysulfides (discharge to 2.1 V) and short chain sulfides (discharge to 1.7 V). The results consistently show chemical shifts for S 2p in PCM-650, suggesting an enhanced adsorption effect. Furthermore, density functional theory (DFT) calculations is used to clarify the molecular binding: carbon/sulfur (0.86 eV), carbon/Li 2 S (0.3 eV), CH 3 -O-PO 3 H 2 /sulfur (1.24 eV), and CH 3 -O-PO 3 H 2 /Li 2 S (1.81 eV). It shows that dihydrogen phosphate group can significantly enhance the binding with sulfur and sulfide, consistent with XPS results. Consequently a CM functionalised with dihydrogen phosphate shows great potential as the sulfur host in a Li-S battery. [ABSTRACT FROM AUTHOR]

Li-S batteries have been extensively studied using rigid carbon as the host for sulfur encapsulation, but improving the properties with a reduced electrolyte amount remains a significant challenge. This is critical for achieving high energy density. Here, we developed a soft PEO10LiTFSI polymer swellable gel as a nanoscale reservoir to trap the polysulfides under lean electrolyte conditions. The PEO10LiTFSI gel immobilizes the electrolyte and confines polysulfides within the ion conducting phase. The Li-S cell with a much lower electrolyte to sulfur ratio (E/S) of 4 gE/gS (3.3 mLE/gS) could deliver a capacity of 1200 mA h/g, 4.6 mA h/cm², and good cycle life. The accumulation of polysulfide reduction products, such as Li2S, on the cathode, is identified as the potential mechanism for capacity fading under lean electrolyte conditions. [ABSTRACT FROM AUTHOR]