Enhanced Chemical Immobilization and Catalytic Conversion of Polysulfide Intermediates Using Metallic Mo Nanoclusters for High-Performance Li-S Batteries

A Mott-Schottky Heterojunction with Strong Chemisorption and Fast Conversion Effects for Room-Temperature Na-S Batteries

The practical application of the room-temperature sodium-sulfur (RT Na-S) batteries is currently limited by low reversible capacity and serious capacity decay due to the sluggish reaction kinetics and shuttle effect. It is necessary to design a suitable sulfur host integrated with electrocatalysts to realize effective chemisorption and catalysis of sodium polysulfides (NaPSs). Herein, under the guidance of theoretical calculation, the Mott-Schottky heterojunction with a built-in electric field composed of iron (Fe) and iron disulfide (FeS2) components anchored on a porous carbon matrix (Fe/FeS2-PC) is designed and prepared. The enhanced chemisorption effect of Fe, the fast electrocatalytic effect of FeS2, and the fast transfer effect of the built-in electric field within the Fe/FeS2 heterojunction in the cathode of RT Na-S batteries work together to effectively improve the electrochemical performance. As a result, the Fe/FeS2-PC@S cathode exhibits high reversible capacity (815 mAh g-1 after 150 cycles at 0.2 A g-1) and excellent stability (516 mAh g-1 after 600 cycles at 5 A g-1, with only 0.07% decay per cycle). The design of the Fe/FeS2 heterojunction electrocatalyst provides a new strategy for the development of highly stable RT Na-S batteries.

Defect engineering of a TiO2 anatase/rutile homojunction accelerating sulfur redox kinetics for high-performance Na-S batteries

Room-temperature sodium-sulfur (RT Na-S) batteries have the drawbacks of the poor shuttle effect of soluble sodium polysulfides (NaPSs) as well as slow sulfur redox kinetics, which result in poor cycling stability and low capacity, seriously affecting their extensive application. Herein, defect engineering is applied to construct rich oxygen vacancies at the interface of a TiO2 anatase/rutile homojunction (OV-TRA) to enhance sulfur affinity and redox reaction kinetics. Combining structural characterizations with electrochemical analysis reveals that OV-TRA well alleviates the shuttle effect of NaPSs and precipitates the deposition and diffusion kinetics of Na2S. Consequently, S/OV-TRA provides excellent electrochemical performance with a reversible capacity of 870 mA h g-1 at 0.1 C after 100 cycles and a long-term cycling capability of 759 mA h g-1 at 1 C after 1000 cycles. This work provides an effective interfacial defect engineering strategy to promote the application of metal oxides in RT Na-S batteries.

Rechargeable Metal-Sulfur Batteries: Key Materials to Mechanisms

Rechargeable metal-sulfur batteries are considered promising candidates for energy storage due to their high energy density along with high natural abundance and low cost of raw materials. However, they could not yet be practically implemented due to several key challenges: (i) poor conductivity of sulfur and the discharge product metal sulfide, causing sluggish redox kinetics, (ii) polysulfide shuttling, and (iii) parasitic side reactions between the electrolyte and the metal anode. To overcome these obstacles, numerous strategies have been explored, including modifications to the cathode, anode, electrolyte, and binder. In this review, the fundamental principles and challenges of metal-sulfur batteries are first discussed. Second, the latest research on metal-sulfur batteries is presented and discussed, covering their material design, synthesis methods, and electrochemical performances. Third, emerging advanced characterization techniques that reveal the working mechanisms of metal-sulfur batteries are highlighted. Finally, the possible future research directions for the practical applications of metal-sulfur batteries are discussed. This comprehensive review aims to provide experimental strategies and theoretical guidance for designing and understanding the intricacies of metal-sulfur batteries; thus, it can illuminate promising pathways for progressing high-energy-density metal-sulfur battery systems.

Co/CoS2 Heterojunction Embedded in N, S-Doped Hollow Nanocage for Enhanced Polysulfides Conversion in High-Performance Lithium-Sulfur Batteries

Modulating the electronic configuration of the substrate to achieve the optimal chemisorption toward polysulfides (LiPSs) for boosting polysulfide conversion is a promising way to the efficient Li-S batteries but filled with challenges. Herein, a Co/CoS2 heterostructure is elaborately built to tuning d-orbital electronic structure of CoS2 for a high-performance electrocatalyst. Theoretical simulations first evidence that Co metal as the electron donator can form a built-in electric field with CoS2 and downshift the d-band center, leading to the well-optimized adsorption strength for lithium polysulfides on CoS2 , thus contributing a favorable way for expediting the redox reaction kinetics of LiPSs. As verification of prediction, a Co/CoS2 heterostructure implanted in porous hollow N, S co-doped carbon nanocage (Co/CoS2 @NSC) is designed to realize the electronic configuration regulation and promote the electrochemical performance. Consequently, the batteries assembled with Co/CoS2 @NSC cathode display an outstanding specific capacity and an admirable cycling property as well as a salient property of 8.25 mAh cm-2 under 8.18 mg cm-2 . The DFT calculation also reveals the synergistic effect of N, S co-doping for enhancing polysulfide adsorption as well as the detriment of excessive sulfur doping.

High-Rate Lithium-Selenium Batteries Boosted by a Multifunctional Janus Separator Over a Wide Temperature Range of -30 °C to 60 °C

Lithium-selenium batteries are characterized by high volumetric capacity comparable to Li-S batteries, while ≈1025 times higher electrical conductivity of Se than S is favorable for high-rate capability. However, they also suffer from the "shuttling effect" of lithium polyselenides (LPSes) and Li dendrite growth. Herein, a multifunctional Janus separator is designed by coating hierarchical nitrogen-doped carbon nanocages (hNCNC) and AlN nanowires on two sides of commercial polypropylene (PP) separator to overcome these hindrances. At room temperature, the Li-Se batteries with the Janus separator exhibit an unprecedented high-rate capability (331 mAh g-1 at 25 C) and retain a high capacity of 408 mAh g-1 at 3 C after 500 cycles. Moreover, the high retained capacities are achieved over a wide temperature range from -30 °C to 60 °C, showing the potential application under extreme environments. The excellent performances result from the "1+1>2" synergism of suppressed LPSes shuttling by chemisorption and electrocatalysis of hNCNC on the cathode side and suppressed Li-dendrite growth by thermally conductive AlN-network on the anode side, which can be well understood by the "Bucket Effect". This Janus separator provides a general strategy to develop high-performance lithium-chalcogen (Se, S, SeS2 ) batteries.

Local Built-In Field at the Sub-nanometric Heterointerface Mediates Cascade Electrochemical Conversion of Lithium-sulfur Batteries

Heterogeneous catalytic mediators have been proposed to play a vital role in enhancing the multiorder reaction and nucleation kinetics in multielectron sulfur electrochemistry. However, the predictive design of heterogeneous catalysts is still challenging, owing to the lack of in-depth understanding of interfacial electronic states and electron transfer on cascade reaction in Li-S batteries. Here, a heterogeneous catalytic mediator based on monodispersed titanium carbide sub-nanoclusters embedded in titanium dioxide nanobelts is reported. The tunable catalytic and anchoring effects of the resulting catalyst are achieved by the redistribution of localized electrons caused by the abundant built-in fields in heterointerfaces. Subsequently, the resulting sulfur cathodes deliver an areal capacity of 5.6 mAh cm-2 and excellent stability at 1 C under sulfur loading of 8.0 mg cm-2 . The catalytic mechanism especially on enhancing the multiorder reaction kinetic of polysulfides is further demonstrated via operando time-resolved Raman spectroscopy during the reduction process in conjunction with theoretical analysis.

Double-Transition-Metal MXene Films Promoting Deeply Rechargeable Magnesium Metal Batteries

Magnesium metal batteries are promising candidates for next-generation high-energy-density and low-cost energy storage systems. Their application, however, is precluded by infinite relative volume changes and inevitable side reactions of Mg metal anodes. These issues become more pronounced at large areal capacities that are required for practical batteries. Herein, for the first time, double-transition-metal MXene films are developed to promote deeply rechargeable magnesium metal batteries using Mo2 Ti2 C3 as a representative example. The freestanding Mo2 Ti2 C3 films, which are prepared using a simple vacuum filtration method, possess good electronic conductivity, unique surface chemistry, and high mechanical modulus. These superior electro-chemo-mechanical merits of Mo2 Ti2 C3 films help to accelerate electrons/ions transfer, suppress electrolyte decomposition and dead Mg formation, as well as maintain electrode structural integrity during long-term and large-capacity operation. As a result, the as-developed Mo2 Ti2 C3 films exhibit reversible Mg plating/stripping with high Coulombic efficiency of 99.3% at a record-high capacity of 15 mAh cm-2 . This work not only sheds innovative insights into current collector design for deeply cyclable Mg metal anodes, but also paves the way for the application of double-transition-metal MXene materials in other alkali and alkaline earth metal batteries.

Boosting Lean Electrolyte Lithium-Sulfur Battery Performance with Transition Metals: A Comprehensive Review

Lithium-sulfur (Li-S) batteries have received widespread attention, and lean electrolyte Li-S batteries have attracted additional interest because of their higher energy densities. This review systematically analyzes the effect of the electrolyte-to-sulfur (E/S) ratios on battery energy density and the challenges for sulfur reduction reactions (SRR) under lean electrolyte conditions. Accordingly, we review the use of various polar transition metal sulfur hosts as corresponding solutions to facilitate SRR kinetics at low E/S ratios (< 10 µL mg-1), and the strengths and limitations of different transition metal compounds are presented and discussed from a fundamental perspective. Subsequently, three promising strategies for sulfur hosts that act as anchors and catalysts are proposed to boost lean electrolyte Li-S battery performance. Finally, an outlook is provided to guide future research on high energy density Li-S batteries.

Metal-Organic-Framework-Derived 3D Hierarchical Matrixes for High-Performance Flexible Li-S Batteries

Lithium-sulfur (Li-S) batteries have shown exceptional theoretical energy densities, making them a promising candidate for next-generation energy storage systems. However, their practical application is limited by several challenging issues, such as uncontrollable Li dendrite growth, sluggish electrochemical kinetics, and the shuttling effect of lithium polysulfides (LiPSs). To overcome these issues, we designed and synthesized hierarchical matrixes on carbon cloth (CC) by using metal-organic frameworks (MOFs). ZnO nanosheet arrays were used as anode hosts (CC-ZnO) to enable stable Li plating and stripping. The symmetric cell with CC-ZnO@Li was demonstrated to have enhanced cycling stability, with a voltage hysteresis of ∼25 mV for over 800 h at 1 mA cm^-2 and 1 mAh cm^-2. To address the cathode challenges, we developed a multifunctional CC-NC-Co cathode host with physical confinement, chemical anchoring, and excellent electrocatalysis. The full cells with CC-ZnO@Li anodes and CC-NC-Co@S cathodes exhibited excellent electrochemical performance, with long cycling life (0.02% and 0.03% capacity decay per cycle when cycling 900 times at 0.5 C and 600 times at 1 C, respectively) and outstanding rate performance (793 mAh g^-1 at 4 C). Additionally, the pouch cell based on the flexible CC-ZnO@Li anode and CC-NC-Co@S cathode showed good stability in different bending states. Overall, our study presents an effective strategy for preparing flexible Li and S hosts with hierarchical structures derived from MOF, which can pave the way for high-performance Li-S batteries.

Efficient Regulation of Polysulfides by MoS2 /MoO3 Heterostructures for High-Performance Li-S Batteries

The notorious shuttle effect and sluggish conversion of polysulfides seriously hinder the practical application of Lithium-sulfur (Li-S) batteries. In this study, a novel architecture of MoS₂ /MoO₃ heterostructure uniformly distributed on carbon nanotubes (MoS₂ /MoO₃ @CNT) is designed and introduced into Li-S batteries via decorating commercial separator to regulate the redox reactions of polysulfides. Systematic experiments and theoretical calculations showed that the heterostructure not only provides sufficient surface affinity to capture polysulfides and acts as an active catalyst to promote the conversion of polysulfides, but also the highly conductive CNT enables rapid electron/ion migration. As a result, Li-S batteries with the MoS₂ /MoO₃ @CNT-PP separator deliver an impressive reversible capacity (1015 mAh g^-1 at 0.2 A g^-1 after 100 cycles), excellent rate capacity (873 mAh g^-1 at 5 A g^-1 ), and low self-discharge capacity loss (94.6% capacity retention after 7 days of standing). Moreover, even at an elevated temperature of 70 °C, it still exhibits high-capacity retention (800 mAh g^-1 at 1 A g^-1 after 100 cycles). Encouragingly, when the sulfur load is increased to 8.7 mg cm^-2 , the high reversible areal capacity of 6.61 mAh cm^-2 can be stably maintained after 100 cycles, indicating a high potential for practical application.

Coupling of Oxygen Vacancies and Heterostructure on Fe3 O4 via an Anion Doping Strategy to Boost Catalytic Activity for Lithium-Sulfur Batteries

The sluggish reaction kinetics and severe shutting behaviors of sulfur cathodes are the major roadblocks to realizing the practical application of lithium-sulfur (Li-S) batteries and need to be solved through designing/constructing rational sulfur hosts. Herein, an effective alternative material of Fe₃ O_{4- x} /FeP in-situ embedded in N-doped carbon-tube (Fe₃ O_{4- x} /FeP/NCT) is proposed. In this fabricated heterostructure, NCT skeleton works as a sulfur host provides physical barrier for lithium polysulfides (LiPSs), while Fe₃ O_{4- x} /FeP heterostructure with abundant oxygen vacancies provides double active centers to simultaneously accelerate e^- /Li⁺ diffusion/transport kinetics and catalysis for LiPSs. Through the respective advantages, Fe₃ O_{4- x} /FeP/NCT exhibits synergy enhancement effect for restraining sulfur dissolution and enhancing its conversion kinetics. Furthermore, the promoted ion diffusion kinetics, enhanced electrical conductivity, and increased active sites of Fe₃ O_{4- x} /FeP/NCT are enabled by oxygen vacancies as well as the heterogeneous interfacial contact, which is clearly confirmed by experimental and first-principles calculations. By virtue of these superiorities, the constructed cathode shows excellent long-term cycling stability and a high-rate capability up to 10 C. Specially, a high areal capacity of 7.2 mAh cm^-2 is also achieved, holding great promise for utilization in advanced Li-S batteries in the future.

Interface Engineering Toward Expedited Li2 S Deposition in Lithium-Sulfur Batteries: A Critical Review

Lithium-sulfur batteries (LSBs) with superior energy density are among the most promising candidates of next-generation energy storage techniques. As the key step contributing to 75% of the overall capacity, Li₂ S deposition remains a formidable challenge for LSBs applications because of its sluggish kinetics. The severe kinetic issue originates from the huge interfacial impedances, indicative of the interface-dominated nature of Li₂ S deposition. Accordingly, increasing efforts have been devoted to interface engineering for efficient Li₂ S deposition, which has attained inspiring success to date. However, a systematic overview and in-depth understanding of this critical field are still absent. In this review, the principles of interface-controlled Li₂ S precipitation are presented, clarifying the pivotal roles of electrolyte-substrate and electrolyte-Li₂ S interfaces in regulating Li₂ S depositing behavior. For the optimization of the electrolyte-substrate interface, efforts on the design of substrates including metal compounds, functionalized carbons, and organic compounds are systematically summarized. Regarding the regulation of electrolyte-Li₂ S interface, the progress of applying polysulfides catholytes, redox mediators, and high-donicity/polarity electrolytes is overviewed in detail. Finally, the challenges and possible solutions aiming at optimizing Li₂ S deposition are given for further development of practical LSBs. This review would inspire more insightful works and, more importantly, may enlighten other electrochemical areas concerning heterogeneous deposition processes.

A Polymer Network Layer Containing Dually Anchored Ionic Liquids for Stable Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries with high sulfur utilization, long-cycle life, and dendrite-free features hold great promise for the development of next-generation energy storage devices of high energy density. Considerable efforts have been committed to solving the polysulfide shuttle problem toward highly stable Li-S batteries. Here, a unique polymer network containing dually anchored ionic liquids (DA-PIL) is devolped to improve the cycling performance and coulombic efficiency of Li-S batteries. This DA-PIL electrolyte incorporates the amphiphilicity of both the polysulfides anion and lithium cation, creating an ionic function layer on polypropylene separator. Noteworthily, the DA-PIL network is "clean" in the sense that no free ionic specifies are introduced to the electrolyte system. The DA-PIL layer not only enables strong supression against polysulfide shuttling but simultaneously allows fast lithium transportation owing to cooperate electrostatic interaction among anchored cations and anions. The DA-PIL layer functionalized on a polypropylene separator can boost excellent stability of Li-S battery with >1600 h cycling test at 0.25 mA cm^-2 . The Li-S cell with DA-PIL layer delivers a higher discharge capacity of 827.4 mAh g^-1 at 1C. A discharge capacity of 630.6 mAh g^-1 is retained after 1000 cycles.

Enhanced Performance of Li-S Batteries due to Synergistic Adsorption and Catalysis Activity within a Separation Coating Made of Hybridized BNNSs/N-Doping Porous Carbon Fibers

Lithium-sulfur (Li-S) batteries with high theoretical energy density are considered as the most promising devices for rechargeable energy-storage systems. However, their actual applications are rather limited by the shuttle effect of lithium polysulfides (LiPSs) and the sluggish redox kinetics. Here, the boron nitride nanosheets are homodispersedly embedded into N-doping porous carbon fibers (BNNSs/CHFs) by an electrospinning technique and a subsequent in situ pyrolysis process. The hybridized BNNSs/CHFs can be smartly designed as a multifunctional separation coating onto the commercial PP membrane to enhance the electrochemical performance of Li-S batteries. As a result, the Li-S batteries with extra BNNSs/CHF modification deliver a highly reversible discharge capacity of 830.4 mA h g^-1 at a current density of 1 C. Even under 4 C, the discharge specific capacity can reach up to 609.9 mA h g^-1 and maintain at 553.9 mA h g^-1 after 500 cycles, showing a low capacity decay of 0.01836% per cycle. It is considered that the excellent performance is attributed to the synergistic effect of adsorption and catalysis of the BNNSs/CHF coating used. First, this coating can efficiently reduce the charge transfer resistance and enhance Li-ion diffusion, due to increased catalytic activity from strong electronic interactions between BNNSs and N-doping CHFs. Second, the combination of polar BNNSs and abundant pore structures within the hybridized BNNSs/CHF networks can highly facilitate an adsorption for LiPSs. Here, we believed that this work would provide a promising strategy to increase the Li-S batteries' performance by introducing hybridized BNNSs/N-doping carbon networks, which could efficiently suppress the LiPSs' shuttle effect and improve the electrochemical kinetics of Li-S batteries.

Cu-Mo Bimetal Modulated Multifunctional Carbon Nanofibers Promoting the Polysulfides Conversion for High-Sulfur-Loading Lithium-Sulfur Batteries

High sulfur loading is essential for achieving high energy density lithium-sulfur (Li-S) batteries. However, serious issues such as low sulfur utilization, poor cycling stability, and sluggish rate performance have been exposed when increasing the sulfur loading for freestanding cathodes. To solve these problems, the adsorption/catalytic ability of high-sulfur-loading cathode toward polysulfides must be improved. Herein, based on excellent properties of cationic MOFs, we proposed that Cu-Mo bimetallic nanoparticles embedded in multifunctional freestanding nitrogen-doped porous carbon nanofibers (Cu-Mo@NPCN) with efficient catalytic sites could be prepared by facile MoO₄^2- anion exchange of cationic MOFs. And, the sulfur embedded in Cu-Mo@NPCN was directly used as self-supporting electrodes, enabling a high areal capacity, good rate performance, and decent cycling stability even under high sulfur loading. The freestanding Cu-Mo@NPCN/10.3S cathode achieves a high volumetric capacity of 1163 mA h cm^-3 and a decent areal capacity of 9.3 mA h cm^-2 at 0.2 C with a sulfur loading of 10.3 mg cm^-2. This work provides an innovative approach for engineering a freestanding sulfur cathode and would forward the development of cationic MOF-derived bimetallic catalysts in various energy storage systems.

High Utilization of Composite Magnesium Metal Anodes Enabled by a Magnesiophilic Coating

Metallic magnesium is a promising high-capacity anode material for energy storage technologies beyond lithium-ion batteries. However, most reported Mg metal anodes are only cyclable under shallow cycling (≤1 mAh cm^-2) and thus poor Mg utilization (<3%) conditions, significantly compromising their energy-dense characteristic. Herein, composite Mg metal anodes with high capacity utilization of 75% are achieved by coating magnesiophilic gold nanoparticles on copper foils for the first time. Benefiting from homogeneous ionic flux and uniform deposition morphology, the Mg-plated Au-Cu electrode exhibits high average Coulombic efficiency of 99.16% over 170 h cycling at 75% Mg utilization. Moreover, the full cell based on Mg-plated Au-Cu anode and Mo₆S₈ cathode achieves superior capacity retention of 80% after 300 cycles at a low negative/positive ratio of 1.33. This work provides a simple yet effective general strategy to enhance Mg utilization and reversibility, which can be extended to other metal anodes as well.

Scalable 3D Honeycombed Co3O4 Modified Separators as Polysulfides Barriers for High-Performance Li-S Batteries

Lithium sulfur batteries (LSBs) are regarded as one of the most promising energy storage devices due to the high theoretical capacity and energy density. However, the shuttling lithium polysulfides (LiPSs) from the cathode and the growing lithium dendrites on the anode limit the practical application of LSBs. To overcome these challenges, a novel three-dimensional (3D) honeycombed architecture consisting of a local interconnected Co₃O₄ successfully assembled into a scalable modified layer through mutual support, which is coated on commercial separators for high-performance LSBs. On the basis of the 3D honeycombed architecture, the modified separators not only suppress effectively the "shuttle effects" but also allow for fast lithium-ions transportation. Moreover, the theoretical calculations results exhibit that the collaboration of the exposed (111) and (220) crystal planes of Co₃O₄ is able to effectively anchor LiPSs. As expected, LSBs with 3D honeycombed Co₃O₄ modified separators present a reversible specific capacity with 1007 mAh g^-1 over 100 cycles at 0.1 C. More importantly, a high reversible capacity of 808 mAh g^-1 over 300 cycles even at 1 C is also acquired with the modified separators. Therefore, this proposed strategy of 3D honeycombed architecture Co₃O₄ modified separators will give a new route to rationally devise durable and efficient LSBs.

Molybdenum Carbide Electrocatalyst In Situ Embedded in Porous Nitrogen-Rich Carbon Nanotubes Promotes Rapid Kinetics in Sodium-Metal-Sulfur Batteries

This is the first report of molybdenum carbide-based electrocatalyst for sulfur-based sodium-metal batteries. MoC/Mo₂ C is in situ grown on nitrogen-doped carbon nanotubes in parallel with formation of extensive nanoporosity. Sulfur impregnation (50 wt% S) results in unique triphasic architecture termed molybdenum carbide-porous carbon nanotubes host (MoC/Mo₂ C@PCNT-S). Quasi-solid-state phase transformation to Na₂ S is promoted in carbonate electrolyte, with in situ time-resolved Raman, X-ray photoelectron spectroscopy, and optical analyses demonstrating minimal soluble polysulfides. MoC/Mo₂ C@PCNT-S cathodes deliver among the most promising rate performance characteristics in the literature, achieving 987 mAh g^-1 at 1 A g^-1 , 818 mAh g^-1 at 3 A g^-1 , and 621 mAh g^-1 at 5 A g^-1 . The cells deliver superior cycling stability, retaining 650 mAh g^-1 after 1000 cycles at 1.5 A g^-1 , corresponding to 0.028% capacity decay per cycle. High mass loading cathodes (64 wt% S, 12.7 mg cm^-2 ) also show cycling stability. Density functional theory demonstrates that formation energy of Na₂ S_x (1 ≤ x ≤ 4) on surface of MoC/Mo₂ C is significantly lowered compared to analogous redox in liquid. Strong binding of Na₂ S_x (1 ≤ x ≤ 4) on MoC/Mo₂ C surfaces results from charge transfer between the sulfur and Mo sites on carbides' surface.

Recent Advances in Solar Rechargeable Seawater Batteries Based on Semiconductor Photoelectrodes

With the ever-increasing demand for energy in the world, the tendency to use renewable energies has been growing rapidly. Sunlight, as an inexhaustible energy source, and the oceans, as one of the most valuable treasures on Earth, are available for free. Simultaneous exploitation of these two sources of energy and matter (sunlight and oceans) in one configuration can provide a sustainable solution for future energy supply. Among the various types of such energy storage and conversion systems, solar rechargeable seawater batteries (SRSBs) can meet this need by storing the chemical energy of seawater by receiving solar energy. SRSBs consist of two compartments: a closed compartment including a sodium metal anode in an organic liquid electrolyte, and an open compartment containing a semiconductor photoelectrode immersed in seawater, which are separated from each other by a ceramic solid electrolyte membrane. In this complex system, the photoelectrode is irradiated by sunlight, whereby electrons are excited and reach the Na metal anode after passing though the external circuit. The ceramic solid electrolyte harvests only sodium ions from seawater and transfers them to the anodic part, where the transferred ions are reduced to sodium metal atoms. At the same time, an oxygen evolution reaction takes place at the cathodic part. In this way, the battery is charged. The use of a photoelectrode in the charging process significantly increases the voltage efficiency of SRSBs to more than 90%, whereas a cell with only the seawater compartment (without a photoelectrode) will not deliver satisfactory performance. Therefore, to achieve very high efficiencies, designing an accurate system with the best components is absolutely necessary. This review focuses on the working principle of SRSBs, at the same time explaining the effect of key components on the performance and stability of SRSBs. The role of the semiconductor photoelectrode in improving the voltage efficiency of SRSBs is also described in detail, and finally strategies proposed to overcome obstacles to the commercialization of SRSBs are introduced.

Expediting Sulfur Reduction/Evolution Reactions with Integrated Electrocatalytic Network: A Comprehensive Kinetic Map

Electrocatalysts are considered the most promising candidates in ameliorating the slow kinetics of Li-S batteries (LSBs), however, the issue of insufficient catalytic capability remains to be addressed. Herein, we report an integrated catalytic network comprising graphitic carbon-encapsulated/bridged ultrafine NiCoP embedded in N, P-codoped carbon (GC-uNiCoP@NPC) as a highly competent catalyst for sulfur-based species conversions. By profiling the evolution map of Li-S chemistry via operando kinetic analyses, GC-uNiCoP@NPC is demonstrated to possess versatile yet efficient catalytic activity for sulfur reduction/evolution reactions, especially the rate-determining heterogeneous phase transitions. As a result, GC-uNiCoP@NPC enables high capacity and stable cycling of sulfur cathode under high areal loading and lean electrolyte. Moreover, pouch cells assembled under practical conditions present promising performance with a specific energy of 302 Wh kg^-1. This work not only conceptually expands the catalyst design for LSBs but also provides a comprehensive insight into the catalyst performance for Li-S chemistry.

An electrochemical sensor based on electrospun MoS2@SnO2 modified carbon nanofiber composite materials for simultaneously detection ofphenacetin and indomethacin

SnO 2 -CNF was prepared by coaxial blending technology, and MoS 2 was grown uniformly on SnO 2 -CNF composite by combining hydrothermal post-treatment step. The uniform distribution of MoS 2 on one-dimensional SnO 2 -CNF can effectively establish a layered three-dimensional structure. So that the prepared MoS 2 coated SnO 2 -CNF composite material has higher surface area and more active sites to obtain better electrochemical performance. We constructed an electrochemical sensor within the composite material with enhanced performance to realize the simultaneous and highly sensitive detection of phenacetin and indomethacin for the first time. The sensor proves the linear ranges of 0.050-7200 μM and 0.05-500 μM respectively, and the detection limits were 0.016 μM and 0.013 μM. And the sensor has good anti-interference ability and stability, which also achieves good recovery rate in the actual sample detection .

Polysulfide Catalytic Materials for Fast-Kinetic Metal-Sulfur Batteries: Principles and Active Centers

Benefiting from the merits of low cost, ultrahigh-energy densities, and environmentally friendliness, metal-sulfur batteries (M-S batteries) have drawn massive attention recently. However, their practical utilization is impeded by the shuttle effect and slow redox process of polysulfide. To solve these problems, enormous creative approaches have been employed to engineer new electrocatalytic materials to relieve the shuttle effect and promote the catalytic kinetics of polysulfides. In this review, recent advances on designing principles and active centers for polysulfide catalytic materials are systematically summarized. At first, the currently reported chemistries and mechanisms for the catalytic conversion of polysulfides are presented in detail. Subsequently, the rational design of polysulfide catalytic materials from catalytic polymers and frameworks to active sites loaded carbons for polysulfide catalysis to accelerate the reaction kinetics is comprehensively discussed. Current breakthroughs are highlighted and directions to guide future primary challenges, perspectives, and innovations are identified. Computational methods serve an ever-increasing part in pushing forward the active center design. In summary, a cutting-edge understanding to engineer different polysulfide catalysts is provided, and both experimental and theoretical guidance for optimizing future M-S batteries and many related battery systems are offered.

Conductive Al-Doped ZnO Framework Embedded with Catalytic Nanocages as a Multistage-Porous Sulfur Host in Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries possess many practical challenges including the lithium polysulfide (LiPS) "shuttle effect" and their sluggish conversion kinetics. To address these issues, a unique hierarchical porous architecture, combining highly conductive ordered macroporous skeleton and embedded microporous particles is rationally designed as a dual-effective polysulfide immobilizer and conversion promoter. In this nanoporous architecture, Al-doped ZnO (AZO) acts as a conductive macroporous framework, profiting chemical anchoring of LiPS as well as facilitating electrolyte infiltration and ion diffusion; Co nanoparticle-anchored N-doped carbon (Co-NC) derived from CoZn-metal-organic framework is embedded in the macropores to further strengthen the LiPS adsorption, catalytically accelerating conversion kinetics of LiPS simultaneously. Consequently, the Co-NC@AZO/S cathode delivers a notable rate capability of 635.5 mA h g^-1 at 5 C. A high area capacity of about 5.8 mA h cm^-2 with a mass loading of 6.8 mg cm^-2 is also achieved under a lean electrolyte (E/S = 5.7). Additionally, the Li-S pouch cells equipped with Co-NC@AZO can be extended to sulfur loading as high as 4.0 mg cm^-2, delivering a superb capability of 897.5 mA h g^-1 after 100 cycles. This work puts forward a design for stably cycled and practically viable Li-S batteries.

Manipulating Redox Kinetics of Sulfur Species Using Mott-Schottky Electrocatalysts for Advanced Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries suffer from sluggish sulfur redox reactions under high-sulfur-loading and lean-electrolyte conditions. Herein, a typical Co@NC heterostructure composed of Co nanoparticles and a semiconductive N-doped carbon matrix is designed as a model Mott-Schottky catalyst to exert the electrocatalytic effect on sulfur electrochemistry. Theoretical and experimental results reveal the redistribution of charge and a built-in electric field at the Co@NC heterointerface, which are critical to lowering the energy barrier of polysulfide reduction and Li₂S oxidation in the discharge and charge process, respectively. With Co@NC Mott-Schottky catalysts, the Li-S batteries display an ultrahigh capacity retention of 92.1% and a system-level gravimetric energy density of 307.8 Wh kg^-1 under high S loading (10.73 mg cm^-2) and lean electrolyte (E/S = 5.9 μL mg_sulfur^-1) conditions. The proposed Mott-Schottky heterostructure not only deepens the understanding of the electrocatalytic effect in Li-S chemistry but also inspires a rational catalyst design for advanced high-energy-density batteries.

Strategies for Polysulfide Immobilization in Sulfur Cathodes for Room-Temperature Sodium-Sulfur Batteries

Room-temperature sodium-sulfur batteries are one of the most attractive energy storage systems due to their low cost and ultrahigh energy density (2600 W h kg^-1 ). During the charge/discharge process, the sulfur can react with sodium via a multistep redox reaction to obtain a high specific capacity (1675 mA h g^-1 ). However, these batteries face the difficult challenge of the "shuttle effect," which hinders their practical application. Many strategies have been employed to address this issue on sulfur electrodes, such as intact physical confinement, chemical inhibition, and electrocatalysis. In this review, the mechanisms of the abovementioned strategies are summarized, the remaining issues are clarified, and research directions are proposed for developing advanced sodium-sulfur batteries.

Pt-NbC Composite as a Bifunctional Catalyst for Redox Transformation of Polysulfides in High-Rate-Performing Lithium-Sulfur Batteries

Accelerating the redox reaction of polysulfides via catalysis is an effective way to suppress the shuttling effect in lithium-sulfur (Li-S) cells. However, recent studies have mainly focused on the singular function of the catalyst, i.e., either oxidation or reduction of polysulfides. As such, the goal of rapid cycling of sulfur species remains to be highly desired. Herein, a Pt-carbide composite as a bifunctional catalyst was developed to simultaneously accelerate both the reduction of soluble polysulfides and the oxidation of insoluble Li₂S/Li₂S₂. Typically, a Pt-NbC composite was synthesized by growing Pt nanoparticles on the surface of NbC, and the resultant intimate interface in the hybrid is a key component for the bifunctional catalysis. During the reduction process, polysulfides could be grabbed on the surface of NbC via strong adsorption, and then these trapped polysulfides could be catalytically converted by Pt nanoparticles. During the oxidation process, both NbC and Pt exhibited catalytic activities for the dissolution of Li₂S. This process could lead to the renewal of the surface of the catalyst. By combining the sulfur cathode with a Pt-NbC-CNT (Pt-NbC anchored on a carbon nanotube)-coated separator, the cell was able to demonstrate a high initial capacity of 1382 mAh g^-1 at a current density of 0.2C. Furthermore, the cell was able to achieve an exceptional rate capability of 795 mAh g^-1 at 5C, and it was also able to show significantly inhibited self-discharge behavior. Thus, this work explores the catalyst design and the mechanism of a bifunctional catalyst for the performance enhancement in Li-S cells.

Recent Progress in High-Performance Lithium Sulfur Batteries: The Emerging Strategies for Advanced Separators/Electrolytes Based on Nanomaterials and Corresponding Interfaces

Lithium-sulfur (Li-S) batteries, possessing excellent theoretical capacities, low cost and nontoxicity, are one of the most promising energy storage battery systems. However, poor conductivity of elemental S and the "shuttle effect" of lithium polysulfides hinder the commercialization of Li-S batteries. These problems are closely related to the interface problems between the cathodes, separators/electrolytes and anodes. The review focuses on interface issues for advanced separators/electrolytes based on nanomaterials in Li-S batteries. In the liquid electrolyte systems, electrolytes/separators and electrodes system can be decorated by nano materials coating for separators and electrospinning nanofiber separators. And, interface of anodes and electrolytes/separators can be modified by nano surface coating, nano composite metal lithium and lithium nano alloy, while the interface between cathodes and electrolytes/separators is designed by nano metal sulfide, nanocarbon-based and other nano materials. In all solid-state electrolyte systems, the focus is to increase the ionic conductivity of the solid electrolytes and reduce the resistance in the cathode/polymer electrolyte and Li/electrolyte interfaces through using nanomaterials. The basic mechanism of these interface problems and the corresponding electrochemical performance are discussed. Based on the most critical factors of the interfaces, we provide some insights on nanomaterials in high-performance liquid or state Li-S batteries in the future.

Tunable Nitrogen-Doping of Sulfur Host Nanostructures for Stable and Shuttle-Free Room-Temperature Sodium-Sulfur Batteries

Room-temperature sodium-sulfur batteries have potential in stationary applications, but challenges such as loss of active sulfur and low electrical conductivity must be solved. Nitrogen-doped nanocarbon host cathodes have been employed in metal-sulfur batteries: polar interactions mitigate the loss of sulfur, while the conductive nanostructure addresses the low conductivity. Nevertheless, these two properties run contrary to each other as greater nitrogen-doping of nanocarbon hosts is associated with lower conductivity. Herein, we investigate the polarity-conductivity dilemma to determine which of these properties have the stronger influence on cycling performance. Lower carbonization temperatures produce more pyridinic nitrogen and pyrrolic nitrogen, which from density functional theory calculations preferentially bind discharge products (Na₂S and short-chain polysulfides). Despite its lower conductivity, the highly doped composite showed better Coulombic efficiency and stability, retaining a high capacity of 980 mAh g_(S)^-1 after 800 cycles. Our findings represent a paradigm shift where nitrogen-doping should be prioritized in designing shuttle-free, long-life sodium-sulfur batteries.

To Promote the Catalytic Conversion of Polysulfides Using Ni-B Alloy Nanoparticles on Carbon Nanotube Microspheres under High Sulfur Loading and a Lean Electrolyte

Despite their high theoretical energy density, the application of lithium-sulfur batteries is seriously hindered by the polysulfide shuttle and sluggish kinetics, especially with high sulfur loading and under low electrolyte usage. Herein, to facilitate the conversion of lithium polysulfides, nickel-boron (Ni-B) alloy nanoparticles, dispersed uniformly on carbon nanotube microspheres (CNTMs), are used as sulfur hosts for lithium-sulfur batteries. It is demonstrated that Ni-B alloy nanoparticles can not only anchor polysulfides through Ni-S and B-S interactions but also exhibit high electrocatalytic capability toward the conversion of intermediate polysulfide species. In addition, the intertwined CNT microspheres provide an additional conductive scaffold in response to the fast electrochemical redox. The enhanced redox kinetics is beneficial to improve the specific capacity and cycling stability of the sulfur cathode, based on the fast conversion of lithium polysulfides and effective deposition of the final sulfide products. Conclusively, the S/Ni-B/CNTM composite delivers a high specific capacity (1112.7 mAh g_s^-1) along with good cycle performance under both high sulfur loading (8.3 mg cm^-2) and a lean electrolyte (3 μL mg_s^-1). Consequently, this study opens up a path to design new sulfur hosts toward lithium-sulfur batteries.

Hierarchical Nanoreactor with Multiple Adsorption and Catalytic Sites for Robust Lithium-Sulfur Batteries

Developing high-performance cathode host materials is fundamental to solve the low utilization of sulfur, the sluggish redox kinetics, and the lithium polysulfide (LiPS) shuttle effect in lithium-sulfur batteries (LSBs). Here, a multifunctional Ag/VN@Co/NCNT nanocomposite with multiple adsorption and catalytic sites within hierarchical nanoreactors is reported as a robust sulfur host for LSB cathodes. In this hierarchical nanoreactor, heterostructured Ag/VN nanorods serve as a highly conductive backbone structure and provide internal catalytic and adsorption sites for LiPS conversion. Interconnected nitrogen-doped carbon nanotubes (NCNTs), in situ grown from the Ag/VN surface, greatly improve the overall specific surface area for sulfur dispersion and accommodate volume changes in the reaction process. Owing to their high LiPS adsorption ability, outer Co nanoparticles at the top of the NCNTs catch escaped LiPS, thus effectively suppressing the shuttle effect and enhancing kinetics. Benefiting from the multiple adsorption and catalytic sites of the developed hierarchical nanoreactors, Ag/VN@Co/NCNTs@S cathodes display outstanding electrochemical performances, including a superior rate performance of 609.7 mAh g^-1 at 4 C and a good stability with a capacity decay of 0.018% per cycle after 2000 cycles at 2 C. These properties demonstrate the exceptional potential of Ag/VN@Co/NCNTs@S nanocomposites and approach LSBs closer to their real-world application.

Manipulating Oxidation of Silicon with Fresh Surface Enabling Stable Battery Anode

Silicon (Si)-based material is a promising anode material for next-generation lithium-ion batteries (LIBs). Herein, we report the fabrication of a silicon oxide-carbon (SiO_x/C) nanocomposite through the reaction between silicon particles with fresh surface and H₂O in a mild hydrothermal condition, as well as conducting carbon coating synchronously. We found that controllable oxidation could be realized for Si particles to produce uniform SiO_x after the removal of the native passivation layer. The uniform oxidation and conductive coating offered the as-fabricated SiO_x/C composite good stability at both particle and electrode level over electrochemical cycling. The as-fabricated SiO_x/C composite delivered a high reversible capacity of 1133 mAh g^-1 at 0.5 A g^-1 with 89.1% capacity retention after 200 cycles. With 15 wt % SiO_x/C composite, graphite-SiO_x/C hybrid electrode displayed a high reversible specific capacity of 496 mAh g^-1 and stable electrochemical cycling with a capacity retention of 90.1% for 100 cycles.

Oxygen doping in antimony sulfide nanosheets to facilitate catalytic conversion of polysulfides for lithium-sulfur batteries

A high-performance catalyst, O-doped Sb₂S₃ nanosheets (SS-O NSs), is synthesized and introduced into lithium-sulfur batteries. Owing to their good conductivity, strong adsorbability/catalytic effect to polysulfides and fast Li⁺ diffusion, the SS-O NSs-modified cathodes can effectively mitigate the shuttle effect, thus achieving outstanding electrochemical performance.

Bifunctional Fluorinated Separator Enabling Polysulfide Trapping and Li Deposition for Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) are deemed as one of the most promising next generation energy storage system substitutes for conventional lithium ion batteries due to their high energy density, low cost, and environmental friendliness. The practical application of LSBs has long been blocked by the serious lithium polysulfide (LiPS) shuttle effect and notorious Li dendrite growth, inducing fast capacity decay and limited cycling lifespan. Herein, fluorinated carbon prepared via a safe and scalable strategy has rationally been coated on a separator affording bifunctional fluorinated Celgard (F-Celgard) for LSB construction. The F-Celgard shows superior Li⁺ flux modulation and LiPS trapping capability, which has been verified by the density function theory calculations. The Li symmetric cells demonstrate long and stable Li plating/stripping with much smaller polarization voltage and dendrite-free Li deposition. In addition, LSBs show superior rate performances with higher discharge capacities and long-time stable cycling over 1000 cycles at 1 C with a low decay rate of ∼0.038% per cycle. With a high sulfur loading (∼5.2 mg cm^-2), a high initial areal capacity of ∼4.2 mAh cm^-2 can be obtained with a superior capacity retention of ∼91.8% at 0.2 C. This work demonstrates a facile, cost-effective, and scalable strategy toward highly stable LSBs for practical usage.

Material design strategies to improve the performance of rechargeable magnesium-sulfur batteries

Beyond current lithium-ion technologies, magnesium-sulfur (Mg-S) batteries represent one of the most attractive battery chemistries that utilize low cost, sustainable, and high capacity materials. In addition to high gravimetric and volumetric energy densities, Mg-S batteries also enable safer operation due to the lower propensity for magnesium dendrite growth compared to lithium. However, the development of practical Mg-S batteries remains challenging. Major problems such as self-discharge, rapid capacity loss, magnesium anode passivation, and low sulfur cathode utilization still plague these batteries, necessitating advanced material design strategies for the cathode, anode, and electrolyte. This review critically appraises the latest research and design principles to address specific issues in state-of-the-art Mg-S batteries. In the process, we point out current limitations and open-ended questions, and propose future research directions for practical realization of Mg-S batteries and beyond.

Nano Polymorphism-Enabled Redox Electrodes for Rechargeable Batteries

Nano polymorphism (NPM), as an emerging research area in the field of energy storage, and rechargeable batteries, have attracted much attention recently. In this review, the recent progress on the composition and formation of polymorphs, and the evolution processes of different redox electrodes in rechargeable metal-ion, metal-air, and metal-sulfur batteries are highlighted. First, NPM and its significance for rechargeable batteries are discussed. Subsequently, the current NPM modulation strategies of different types of representative electrodes for their corresponding rechargeable battery applications are summarized. The goal is to demonstrate how NPM could tune the intrinsic material properties, and hence, improve their electrochemical activities for each battery type. It is expected that the analysis of polymorphism and electrochemical properties of materials could help identify some "processing-structure-properties" relationships for material design and performance enhancement. Lastly, the current research challenges and potential research directions are discussed to offer guidance and perspectives for future research on NPM engineering.

Enhancing Polysulfide Confinement and Electrochemical Kinetics by Amorphous Cobalt Phosphide for Highly Efficient Lithium-Sulfur Batteries

The application of lithium-sulfur (Li-S) batteries is severely hampered by the shuttle effect and sluggish redox kinetics. Herein, amorphous cobalt phosphide grown on a reduced graphene oxide-multiwalled carbon nanotube (rGO-CNT-CoP(A)) is designed as the sulfur host to conquer the above bottlenecks. The differences between amorphous cobalt phosphide (CoP) and crystalline CoP on the surface adsorption as well as conversion of lithium polysulfides (LiPSs) are investigated by systematical experiments and density-functional theory (DFT) calculations. Specifically, the amorphous CoP not only strengthens the chemical adsorption to LiPSs but also greatly accelerates liquid-phase conversions of LiPSs as well as the nucleation and growth of Li₂S. DFT calculation reveals that the amorphous CoP possesses higher binding energies and lower diffusion energy barriers for LiPSs. In addition, the amorphous CoP features reduced energy gap and the increased electronic concentrations of adsorbed LiPSs near Fermi level. These characteristics contribute to the enhanced chemisorption ability and the accelerated redox kinetics. Simultaneously, the prepared S/rGO-CNT-CoP(A) electrode delivers an impressive initial capacity of 872 mAh g^-1 at 2 C and 617 mAh g^-1 can be obtained after 200 cycles, exhibiting excellent cycling stability. Especially, it achieves outstanding electrochemical performance even under high sulfur loading (5.3 mg cm^-2) and lean electrolyte (E/S = 7 μL_E mg^-1_S) conditions. This work exploits the application potential for amorphous materials and contributes to the development of highly efficient Li-S batteries.

Recent Advances in Molybdenum-Based Materials for Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries as power supply systems possessing a theoretical energy density of as high as 2600 Wh kg^-1 are considered promising alternatives toward the currently used lithium-ion batteries (LIBs). However, the insulation characteristic and huge volume change of sulfur, the generation of dissolvable lithium polysulfides (LiPSs) during charge/discharge, and the uncontrollable dendrite formation of Li metal anodes render Li-S batteries serious cycling issues with rapid capacity decay. To address these challenges, extensive efforts are devoted to designing cathode/anode hosts and/or modifying separators by incorporating functional materials with the features of improved conductivity, lithiophilic, physical/chemical capture ability toward LiPSs, and/or efficient catalytic conversion of LiPSs. Among all candidates, molybdenum-based (Mo-based) materials are highly preferred for their tunable crystal structure, adjustable composition, variable valence of Mo centers, and strong interactions with soluble LiPSs. Herein, the latest advances in design and application of Mo-based materials for Li-S batteries are comprehensively reviewed, covering molybdenum oxides, molybdenum dichalcogenides, molybdenum nitrides, molybdenum carbides, molybdenum phosphides, and molybdenum metal. In the end, the existing challenges in this research field are elaborately discussed.

Metal-Based Electrocatalysts for High-Performance Lithium-Sulfur Batteries: A Review

The lithium-sulfur (Li-S) redox battery system is considered to be the most promising next-generation energy storage technology due to its high theoretical specific capacity (1673 mAh g−1), high energy density (2600 Wh kg−1), low cost, and the environmentally friendly nature of sulfur. Though this system is deemed to be the next-generation energy storage device for portable electronics and electric vehicles, its poor cycle life, low coulombic efficiency and low rate capability limit it from practical applications. These performance barriers were linked to several issues like polysulfide (LiPS) shuttle, inherent low conductivity of charge/discharge end products, and poor redox kinetics. Here, we review the recent developments made to alleviate these problems through an electrocatalysis approach, which is considered to be an effective strategy not only to trap the LiPS but also to accelerate their conversion reactions kinetics. Herein, the influence of different chemical interactions between the LiPS and the catalyst surfaces and their effect on the conversion of liquid LiPS to solid end products are reviewed. Finally, we also discussed the challenges and perspectives for designing cathode architectures to enable high sulfur loading along with the capability to rapidly convert the LiPS.

Enhanced Catalytic Conversion of Polysulfides Using Bimetallic Co7Fe3 for High-Performance Lithium-Sulfur Batteries

Practical applications of lithium-sulfur (Li-S) batteries have been severely hindered by their low capacity, poor rate performance, and fast capacity degradation, which mainly originate from the notorious polysulfide shuttle effect. Herein, with density functional theory calculations, we show that the alloying of Fe into carbon-coated Co not only provides moderate binding interactions with the polysulfides to hinder their diffusion but also serves as an active catalyst in the spontaneous and successive lithiation of S₈ to Li₂S. Based on the fast migration of Li ions and the spontaneous lithiation of Li₂S₂ on the carbon-coated Fe-Co alloy, the entrapping-conversion processes of polysulfides are both thermodynamically and kinetically promoted in redox cycling. Experimentally, rationally designed Co₇Fe₃@porous graphite carbon-carbon nanotubes (Co₇Fe₃@PGC-CNT) electrocatalysts are introduced into Li-S batteries through separator functionalization. Consistent with theoretical predictions, Li-S batteries with Co₇Fe₃@PGC-CNT modified separators exhibit a dramatically enhanced rate capacity (788 and 631 mAh g^-1 at 10 and 15 C rates, respectively) and cycling stability (a slow capacity decay of 0.05% per cycle over 1000 cycles at 2.0 C), which are superior to those of most reported Li-S batteries coupled with state-of-the-art separators. Furthermore, it is shown that the excellent hindering of the shuttle effects enables a high areal capacity of 4.7 mAh cm^-2 after 90 cycles at a high sulfur loading of 6.7 mg cm^-2. Our work provides a feasible method for developing high-energy and long-life Li-S batteries, which might drive the commercialization of Li-S batteries.

Suppressing the Shuttle Effect and Dendrite Growth in Lithium-Sulfur Batteries

Practical applications of lithium-sulfur batteries are simultaneously hindered by two serious problems occurring separately in both electrodes, namely, the shuttle effects of lithium polysulfides and the uncontrollable growth of lithium dendrites. Herein, to explore a facile integrated approach to tackle both problems as well as guarantee the efficient charge transfer, we used two-dimension hexagonal VS₂ flakes as the building blocks to assemble nanotowers on the separators, forming a symmetrical double-side-modified polypropylene separator without blocking the membrane pores. Benefiting from the "sulfiphilic" and "lithiophilic" properties, high interfacial electronic conductivity, and the unique hexagonal tower-form nanostructure, the D-HVS@PP separator not only guarantees the effective suppression of the lithium polysulfide shuttle and the rapid ion/electron transfer but also realizes uniform and stable lithium nucleation and growth during cycling. Hence, just at the expense of an 11% increase in the separator weight (0.14 mg cm^-2), the D-HVS@PP separator delivers an over 16 times higher initial areal capacity (8.3 mAh cm^-2) than a conventional PP separator (0.5 mAh cm^-2) under high sulfur-loading conditions (9.24 mg cm^-2). Even when used under a low electrolyte/sulfur ratio of 4 mL g^-1 and a practically relevant N/P ratio of 1.7, the D-HVS@PP separator still enabled stable cycling with a high cell-level gravimetric energy density. The potentials in broader applications (Li-S pouch battery and Li-LiFePO₄ battery) and the promising commercial prospect (large-scale production and recyclability) of the developed separator are also demonstrated.