A Dual-Functional Conductive Framework Embedded with TiN-VN Heterostructures for Highly Efficient Polysulfide and Lithium Regulation toward Stable Li–S Full Batteries

Lithium–sulfur (Li–S) batteries are strongly considered as next-generation energy storage systems because of their high energy density. However, the shuttling of lithium polysulfides (LiPS), sluggish reaction kinetics, and uncontrollable Li-dendrite growth severely degrade the electrochemical performance of Li–S batteries. Herein, a dual-functional flexible free-standing carbon nanofiber conductive framework in situ embedded with TiN-VN heterostructures (TiN-VN@CNFs) as an advanced host simultaneously for both the sulfur cathode (S/TiN-VN@CNFs) and the lithium anode (Li/TiN-VN@CNFs) is designed. As cathode host, the TiN-VN@CNFs can offer synergistic function of physical confinement, chemical anchoring, and superb electrocatalysis of LiPS redox reactions. Meanwhile, the well-designed host with excellent lithiophilic feature can realize homogeneous lithium deposition for suppressing dendrite growth. Combined with these merits, the full battery (denoted as S/TiN-VN@CNFs || Li/TiN-VN@CNFs) exhibits remarkable electrochemical properties including high reversible capacity of 1110 mAh g⁻¹ after 100 cycles at 0.2 C and ultralong cycle life over 600 cycles at 2 C. Even with a high sulfur loading of 5.6 mg cm⁻², the full cell can achieve a high areal capacity of 5.5 mAh cm⁻² at 0.1 C. This work paves a new design from theoretical and experimental aspects for fabricating high-energy-density flexible Li–S full batteries.     

Low-Bandgap Se-Deficient Antimony Selenide as a Multifunctional Polysulfide Barrier toward High-Performance Lithium–Sulfur Batteries

The shuttling behavior and sluggish conversion kinetics of the intermediate lithium polysulfides (LiPSs) represent the main obstructions to the practical application of lithium–sulfur (Li–S) batteries. Herein, an anion-deficient design of antimony selenide (Sb₂Se_3−x) is developed to establish a multifunctional LiPS barrier toward the inhibition of polysulfide shuttling and enhancement of battery performance. The defect chemistry in the as-developed Sb₂Se_3−x promotes the intrinsic conductivity, strengthens the chemical affinity to LiPSs, and catalyzes the sulfur electrochemical conversion, which are verified by a series of computational and experimental results. Attributed to these unique superiorities, the obtained LiPS barrier efficiently promotes and stabilizes the sulfur electrochemistry, thus enabling excellent Li–S battery performance, e.g., outstanding cyclability over 500 cycles at 1.0 C with a minimum capacity fading rate of 0.027% per cycle, a superb rate capability up to 8.0 C, and a high areal capacity of 7.46 mAh cm⁻² under raised sulfur loading. This work offers a defect engineering strategy toward fast and durable sulfur electrochemistry, holding great promise in developing practically viable Li–S batteries as well as enlightening the material design of related energy storage and conversion systems.     

Regulating Electrochemical Kinetics of CoP by Incorporating Oxygen on Surface for High-Performance Li–S Batteries

Lithium–sulfur (Li–S) batteries are widely studied because of their high theoretical specific capacity and environmental friendliness. However, the further development of Li–S batteries is hindered by the shuttle effect of lithium polysulfides (LiPSs) and the sluggish redox kinetics. Since the adsorption and catalytic conversion of LiPSs mainly occur on the surface of the electrocatalyst, regulating the surface structure of electrocatalysts is an advisable strategy to solve the obstacles in Li–S batteries. Herein, CoP nanoparticles with high oxygen content on surface embedded in hollow carbon nanocages (C/O-CoP) is employed to functionalize the separators and the effect of the surface oxygen content of CoP on the electrochemical performance is systematically explored. Increasing the oxygen content on CoP surface can enhance the chemical adsorption to lithium polysulfides and accelerate the redox conversions kinetics of polysulfides. The cell with C/O-CoP modified separator can achieve the capacity of 1033 mAh g⁻¹ and maintain 749 mAh g⁻¹ after 200 cycles at 2 C. Moreover, DFT calculations are used to reveal the enhancement mechanism of oxygen content on surface of CoP in Li–S chemistry. This work offers a new insight into developing high-performance Li–S batteries from the perspective of surface engineering.     

Cationic Covalent‐Organic Framework as Efficient Redox Motor for High‐Performance Lithium–Sulfur Batteries

The shuttle effect of soluble lithium polysulfides (LiPSs) leads to the rapid decay of sulfur cathode, severely hindering the practical applications of lithium‐sulfur (Li‐S) batteries. To this point, a covalent‐organic framework (COF) with proper cationic sites, which can be utilized as the cathode host of high‐performance Li–S batteries, is reported. The chemical sulfur anchoring within micropores effectively suppresses the dissolution of LiPSs into the electrolyte. During the discharge step, the cationic sites can accept electrons from anode and deliver them to polysulfides to facilitate the polysulfides' disintegration. Meanwhile, the cationic sites can receive electrons from polysulfides and then send them to the anode during the charge process, which promotes the polysulfides oxidation. Thus, both experiments and computational modeling show that the cationic COF can effectively inhibit the shuttle effect of LiPSs and improve the batteries' performances. Compared with electrically neutral COFs, the cationic COF‐based batteries show much better cycling stability even at high current density, for instance, a high specific capacity of 468 mA h g^?1 is retained after 300 cycles at a current density of 4.0 C.     

Furnishing Continuous Efficient Bidirectional Polysulfide Conversion for Long-Life and High-Loading Lithium–Sulfur Batteries via the Built-In Electric Field

Most catalysts cannot accelerate uninterrupted conversion of polysulfides, resulting in poor long-cycle and high-loading performance of lithium–sulfur (Li–S) batteries. Herein, rich p-n junction CoS₂/ZnS heterostructures embedded on N-doped carbon nanosheets are fabricated by ion-etching and vulcanization as a continuous and efficient bidirectional catalyst. The p-n junction built-in electric field in the CoS₂/ZnS heterostructure not only accelerates the transformation of lithium polysulfides (LiPSs), but also promotes the diffusion and decomposition for Li₂S the from CoS₂ to ZnS avoiding the aggregation of lithium sulfide (Li₂S). Meanwhile, the heterostructure possesses a strong chemisorption ability to anchor LiPSs and superior affinity to induce homogeneous Li deposition. The assembled cell with a CoS₂/ZnS@PP separator delivers a cycling stability with a capacity decay of 0.058% per cycle at 1.0 C after 1000 cycles, and a decent areal capacity of 8.97 mA h cm⁻² at an ultrahigh sulfur mass loading of 6 mg cm⁻². This work reveals that the catalyst continuously and efficiently converts polysulfides via abundant built-in electric fields to promote Li–S chemistry.     

Establishing Transition Metal Phosphides as Effective Sulfur Hosts in Lithium–Sulfur Batteries through the Triple Effect of “Confinement–Adsorption–Catalysis”

Structurally optimized transition metal phosphides are identified as a promising avenue for the commercialization of lithium–sulfur (Li–S) batteries. In this study, a CoP nanoparticle-doped hollow ordered mesoporous carbon sphere (CoP-OMCS) is developed as a S host with a “Confinement–Adsorption–Catalysis” triple effect for Li–S batteries. The Li-S batteries with CoP-OMCS/S cathode demonstrate excellent performance, delivering a discharge capacity of 1148 mAh g⁻¹ at 0.5 C and good cycling stability with a low long-cycle capacity decay rate of 0.059% per cycle. Even at a high current density of 2 C after 200 cycles, a high specific discharge capacity of 524 mAh g⁻¹ is maintained. Moreover, a reversible areal capacity of 6.56 mAh cm⁻² is achieved after 100 cycles at 0.2 C, despite a high S loading of 6.8 mg cm⁻². Density functional theory (DFT) calculations show that CoP exhibits enhanced adsorption capacity for sulfur-containing substances. Additionally, the optimized electronic structure of CoP significantly reduces the energy barrier during the conversion of Li₂S₄ (L) to Li₂S₂ (S). In summary, this work provides a promising approach to optimize transition metal phosphide materials structurally and design cathodes for Li–S batteries.     

A High-Efficiency CoSe Electrocatalyst with Hierarchical Porous Polyhedron Nanoarchitecture for Accelerating Polysulfides Conversion in Li–S Batteries

Lithium–sulfur (Li–S) batteries are recognized as promising candidates for next-generation electrochemical energy storage systems owing to their high energy density and cost-effective raw materials. However, the sluggish multielectron sulfur redox reactions are the root cause of most of the issues for Li–S batteries. Herein, a high-efficiency CoSe electrocatalyst with hierarchical porous nanopolyhedron architecture (CS@HPP) derived from a metal–organic framework is presented as the sulfur host for Li–S batteries. The CS@HPP with high crystal quality and abundant reaction active sites can catalytically accelerate capture/diffusion of polysulfides and precipitation/decomposition of Li₂S. Thus, the CS@HPP sulfur cathode exhibits an excellent capacity of 1634.9 mAh g⁻¹, high rate performance, and a long cycle life with a low capacity decay of 0.04% per cycle over 1200 cycles. CoSe nanopolyhedrons are further fabricated on a carbon cloth framework (CC@CS@HPP) to unfold the electrocatalytic activity by its high electrical conductivity and large surface area. A freestanding CC@CS@HPP sulfur cathode with sulfur loading of 8.1 mg cm⁻² delivers a high areal capacity of 8.1 mAh cm⁻² under a lean electrolyte. This work will enlighten the rational design of structure–catalysis engineering of transition-metal-based nanomaterials for diverse applications.     

Conductive FeOOH as Multifunctional Interlayer for Superior Lithium–Sulfur Batteries

The commercial course of Li–S batteries (LSBs) is impeded by several severe problems, such as low electrical conductivity of S, Li₂S₂, and Li₂S, considerable volume variation up to 80% during multiphase transformation and severe intermediation lithium polysulfides (LiPSs) shuttle effect. To solve above problems, conductive FeOOH interlayer is designed as an effective trapper and catalyst to accelerate the conversion of LiPSs in LSBs. FeOOH nanorod is effectively affinitive to S that Fe atoms act as Lewis acid sites to capture LiPSs via strong chemical anchoring capability and dispersion interaction. The excellent electrocatalytic effect enables that reduced charging potential barrier and enhanced electron/ion transport is realized on the FeOOH interlayer to promote LiPSs conversion. Significantly, Li₂S oxidation process is improved on the FeOOH interlayer determined as a combination of reduced Li₂S decomposition energy barrier and enhanced Li‐ion transport. Therefore, the multifunctional FeOOH interlayer with conductive and catalytic features show strong chemisorption with LiPSs and accelerated LiPSs redox kinetics. As a result, LSBs with FeOOH interlayer displays high discharge capacity of 1449 mAh g^?1 at 0.05 C and low capacity decay of 0.05% per cycle at 1 C, as well as excellent rate capability (449 mAh g^?1 at 2 C).     

Defect-engineered Sulfur Vacancy Modified NiCo2S4-x Nanosheet Anchoring Polysulfide for Improved Lithium Sulfur Batteries

The low conductivity of sulfur and the shuttle effect of lithium polysulfides (LiPSs) are the two intrinsic obstacles that limit the application of lithium–sulfur batteries (LSBs). Herein, a sulfur vacancy introduced NiCo₂S₄ nanosheet array grown on carbon nanofiber (CNF) membrane (NiCo₂S_4-x/CNF) is proposed to serve as a self-supporting and binder-free interlayer in LSBs. The conductive CNF skeleton with a non-woven structure can effectively reduce the resistance of the cathode and accommodate volume expansion during charge–discharge process. The bonding between CNF matrix and NiCo₂S₄ nanosheet is enhanced by in situ growth, ensuring fast electron transfer. Besides, the sulfur vacancies in NiCo₂S₄ enhance the chemisorption of LiPSs, and the highly active sites at vacancies can accelerate the LiPSs conversion kinetics. LSB paired with NiCo₂S_4-x/CNF interlayer achieved improved stability in 500 cycles at 0.2 C and long life of 3000 cycles at 3 C. More importantly, a high areal capacity of 9.69 mAh cm⁻² is achieved with a sulfur loading of 10.8 mg cm⁻² and a low electrolyte to sulfur (E/S) ratio of 4.8. This work provides insight into the sulfur vacancy in catalysis design for LiPSs conversion and demonstrates a promising direction for electronic defect engineering in material design for LSBs.     

The Structural and Electronic Engineering of Molybdenum Disulfide Nanosheets as Carbon-Free Sulfur Hosts for Boosting Energy Density and Cycling Life of Lithium–Sulfur Batteries

The compact sulfur cathodes with high sulfur content and high sulfur loading are crucial to promise high energy density of lithium–sulfur (Li–S) batteries. However, some daunting problems, such as low sulfur utilization efficiency, serious polysulfides shuttling, and poor rate performance, are usually accompanied during practical deployment. The sulfur hosts play key roles. Herein, the carbon-free sulfur host composed of vanadium-doped molybdenum disulfide (VMS) nanosheets is reported. Benefiting from the basal plane activation of molybdenum disulfide and structural advantage of VMS, high stacking density of sulfur cathode is allowed for high areal and volumetric capacities of the electrodes together with the effective suppression of polysulfides shuttling and the expedited redox kinetics of sulfur species during cycling. The resultant electrode with high sulfur content of 89 wt.% and high sulfur loading of 7.2 mg cm⁻² achieves high gravimetric capacity of 900.9 mAh g⁻¹, the areal capacity of 6.48 mAh cm⁻², and volumetric capacity of 940 mAh cm⁻³ at 0.5 C. The electrochemical performance can rival with the state-of-the-art those in the reported Li–S batteries. This work provides methodology guidance for the development of the cathode materials to achieve high-energy-density and long-life Li–S batteries.     

Defect-Rich Single Atom Catalyst Enhanced Polysulfide Conversion Kinetics to Upgrade Performance of Li–S Batteries

Lithium–sulfur (Li–S) batteries have attracted considerable attention owing to their extremely high energy densities. However, the application of Li–S batteries has been limited by low sulfur utilization, poor cycle stability, and low rate capability. Accelerating the rapid transformation of polysulfides is an effective approach for addressing these obstacles. In this study, a defect-rich single-atom catalytic material (Fe-N4/DCS) is designed. The abundantly defective environment is favorable for the uniform dispersion and stable existence of single-atom Fe, which not only improves the utilization of single-atom Fe but also efficiently adsorbs polysulfides and catalyzes the rapid transformation of polysulfides. To fully exploit the catalytic activity, catalytic materials are used to modify the routine separator (Fe-N₄/DCS/PP). Density functional theory and in situ Raman spectroscopy are used to demonstrate that Fe-N₄/DCS can effectively inhibit the shuttling of polysulfides and accelerate the redox reaction. Consequently, the Li–S battery with the modified separator achieves an ultralong cycle life (a capacity decay rate of only 0.03% per cycle at a current of 2 C after 800 cycles), and an excellent rate capability (894 mAh g⁻¹ at 3 C). Even at a high sulfur loading of 5.51 mg cm⁻² at 0.2 C, the reversible areal capacity still reaches 5.4 mAh cm⁻².     

Long‐Life Lithium–Sulfur Batteries with a Bifunctional Cathode Substrate Configured with Boron Carbide Nanowires

Developing high‐energy‐density lithium–sulfur (Li–S) batteries relies on the design of electrode substrates that can host a high sulfur loading and still attain high electrochemical utilization. Herein, a new bifunctional cathode substrate configured with boron‐carbide nanowires in situ grown on carbon nanofibers (B₄C@CNF) is established through a facile catalyst‐assisted process. The B₄C nanowires acting as chemical‐anchoring centers provide strong polysulfide adsorptivity, as validated by experimental data and first‐principle calculations. Meanwhile, the catalytic effect of B₄C also accelerates the redox kinetics of polysulfide conversion, contributing to enhanced rate capability. As a result, a remarkable capacity retention of 80% after 500 cycles as well as stable cyclability at 4C rate is accomplished with the cells employing B₄C@CNF as a cathode substrate for sulfur. Moreover, the B₄C@CNF substrate enables the cathode to achieve both high sulfur content (70 wt%) and sulfur loading (10.3 mg cm^?2), delivering a superb areal capacity of 9 mAh cm^?2. Additionally, Li–S pouch cells fabricated with the B₄C@CNF substrate are able to host a high sulfur mass of 200 mg per cathode and deliver a high discharge capacity of 125 mAh after 50 cycles.     

3D Printing of a V8C7–VO2 Bifunctional Scaffold as an Effective Polysulfide Immobilizer and Lithium Stabilizer for Li–S Batteries

Lithium–sulfur (Li–S) batteries have heretofore attracted tremendous interest due to low cost and high energy density. In this realm, both the severe shuttling of polysulfide and the uncontrollable growth of dendritic lithium have greatly hindered their commercial viability. Recent years have witnessed the rapid development of rational approaches to simultaneously regulate polysulfide behaviors and restrain lithium dendritic growth. Nevertheless, the major obstacles for high-performance Li–S batteries still lie in little knowledge of bifunctional material candidates and inadequate explorations of advanced technologies for customizable devices. Herein, a “two-in-one” strategy is put forward to elaborate V₈C₇–VO₂ heterostructure scaffolds via the 3D printing (3DP) technique as dual-effective polysulfide immobilizer and lithium dendrite inhibitor for Li–S batteries. A thus-derived 3DP-V₈C₇–VO₂/S electrode demostrates excellent rate capability (643.5 mAh g⁻¹ at 6.0 C) and favorable cycling stability (a capacity decay of 0.061% per cycle at 4.0 C after 900 cycles). Importantly, the integrated Li–S battery harnessing both 3DP hosts realizes high areal capacity under high sulfur loadings (7.36 mAh cm⁻² at a sulfur loading of 9.2 mg cm⁻²). This work offers insight into solving the concurrent challenges for both S cathode and Li anode throughout 3DP.     

A Transmetalation Synthetic Strategy to Engineer Atomically Dispersed MnN2O2 Electrocatalytic Centers Driving High-Performance Li?S Battery

Sluggish sulfur redox reaction (SROR) kinetics accompanying lithium polysulfides (LiPSs) shuttle effect becomes a stumbling block for commercial application of Li S battery. High-efficient single atom catalysts (SACs) are desired to improve the SROR conversion capability; however, the sparse active sites as well as partial sites encapsulated in bulk-phase are fatal to the catalytic performance. Herein, high loading (5.02 wt.%) atomically dispersed manganese sites (MnSA) on hollow nitrogen-doped carbonaceous support (HNC) are realized for the MnSA@HNC SAC by a facile transmetalation synthetic strategy. The thin-walled hollow structure (≈12 nm) anchoring the unique trans-MnN₂O₂ sites of MnSA@HNC provides a shuttle buffer zone and catalytic conversion site for LiPSs. Both electrochemical measurement and theoretical calculation indicate that the MnSA@HNC with abundant trans-MnN₂O₂ sites have extremely high bidirectional SROR catalytic activity. The assembled Li S battery based on the MnSA@HNC modified separator can deliver a large specific capacity of 1422 mAh g⁻¹ at 0.1 C and stable cycling over 1400 cycles with an ultralow decay rate of 0.033% per cycle at 1 C. More impressively, a flexible pouch cell on account of the MnSA@HNC modified separator may release a high initial specific capacity of 1192 mAh g⁻¹ at 0.1 C and uninterruptedly work after the bending-unbending processes.     

Shielding Polysulfide Intermediates by an Organosulfur-Containing Solid Electrolyte Interphase on the Lithium Anode in Lithium–Sulfur Batteries

The lithium–sulfur (Li–S) battery is regarded as a promising high-energy-density battery system, in which the dissolution–precipitation redox reactions of the S cathode are critical. However, soluble Li polysulfides (LiPSs), as the indispensable intermediates, easily diffuse to the Li anode and react with the Li metal severely, thus depleting the active materials and inducing the rapid failure of the battery, especially under practical conditions. Herein, an organosulfur-containing solid electrolyte interphase (SEI) is tailored for the stabilizaiton of the Li anode in Li–S batteries by employing 3,5-bis(trifluoromethyl)thiophenol as an electrolyte additive. The organosulfur-containing SEI protects the Li anode from the detrimental reactions with LiPSs and decreases its corrosion. Under practical conditions with a high-loading S cathode (4.5 mg_S cm⁻²), a low electrolyte/S ratio (5.0 µL mg_S⁻¹), and an ultrathin Li anode (50 µm), a Li–S battery delivers 82 cycles with an organosulfur-containing SEI in comparison to 42 cycles with a routine SEI. This work provokes the vital insights into the role of the organic components of SEI in the protection of the Li anode in practical Li–S batteries.     

Compactly Coupled Nitrogen‐Doped Carbon Nanosheets/Molybdenum Phosphide Nanocrystal Hollow Nanospheres as Polysulfide Reservoirs for High‐Performance Lithium–Sulfur Chemistry

Lithium–sulfur (Li–S) batteries have been disclosed as one of the most promising energy storage systems. However, the low utilization of sulfur, the detrimental shuttling behavior of polysulfides, and the sluggish kinetics in electrochemical processes, severely impede their application. Herein, 3D hierarchical nitrogen‐doped carbon nanosheets/molybdenum phosphide nanocrystal hollow nanospheres (MoP@C/N HCSs) are introduced to Li–S batteries via decorating commercial separators to inhibit polysulfides diffusion. It acts not only as a polysulfides immobilizer to provide strong physical trapping and chemical anchoring toward polysulfides, but also as an electrocatalyst to accelerate the kinetics of the polysulfides redox reaction, and to lower the Li₂S nucleation/dissolution interfacial energy barrier and self‐discharge capacity loss in working Li–S batteries, simultaneously. As a result, the Li–S batteries with MoP@C/N HCS‐modified separators show superior rate capability (920 mAh g^?1 at 2 C) and stable cycling life with only 0.04% capacity decay per cycle over 500 cycles at 1 C with nearly 100% Coulombic efficiency. Furthermore, the Li–S battery can achieve a high area capacity of 5.1 mAh cm^?2 with satisfied capacity retention when the cathode loading reaches 5.5 mg cm^?2. This work offers a brand new guidance for rational separator design into the energy chemistry of high‐stable Li–S batteries.     

Coordinated Immobilization and Rapid Conversion of Polysulfide Enabled by a Hollow Metal Oxide/Sulfide/Nitrogen-Doped Carbon Heterostructure for Long-Cycle-Life Lithium-Sulfur Batteries

Lithium-sulfur batteries (LSBs) are recognized as the prospective candidate in next-generation energy storage devices due to their gratifying theoretical energy density. Nonetheless, they still face the challenges of the practical application including low utilization of sulfur and poor cycling life derived from shuttle effect of lithium polysulfides (LiPSs). Herein, a hollow polyhedron with heterogeneous CoO/Co₉S₈/nitrogen-doped carbon (CoO/Co₉S₈/NC) is obtained through employing zeolitic imidazolate framework as precursor. The heterogeneous CoO/Co₉S₈/NC balances the redox kinetics of Co₉S₈ with chemical adsorption of CoO toward LiPSs, effectively inhibiting the shuttle of LiPSs. The mechanisms are verified by both experiment and density functional theory calculation. Meanwhile, the hollow structure acts as a sulfur storage chamber, which mitigates the volumetric expansion of sulfur and maximizes the utilization of sulfur. Benefiting from the above advantages, lithium-sulfur battery with S-CoO/Co₉S₈/NC achieves a high initial discharge capacity (1470 mAh g⁻¹ ) at 0.1 C and long cycle life (ultralow capacity attenuation of 0.033% per cycle after 1000 cycles at 1 C). Even under high sulfur loading of 3.0 mg cm⁻² , lithium-sulfur battery still shows the satisfactory electrochemical performance. This work may provide an idea to elevate the electrochemical performance of LSBs by constructing a hollow metal oxide/sulfide/nitrogen-doped carbon heterogeneous structure.     

Chevrel Phase Mo6S8 Nanosheets Featuring Reversible Electrochemical Li-Ion Intercalation as Effective Dynamic-Phase Promoter for Advanced Lithium-Sulfur Batteries

Modifying sulfur cathodes with lithium polysulfides (LiPSs) adsorptive and electrocatalytic host materials is regarded as one of the most effective approaches to address the challenging problems in lithium-sulfur (Li-S) batteries. However, because of the high operating voltage window of Li–S batteries from 1.7 to 2.8 V, most of the host materials cannot participate in the sulfur redox reactions within the same potential region, which exhibit fixed or single functional property, hardly fulfilling the requirement of the complex and multiphase process. Herein, Chevrel phase Mo₆S₈ nanosheets with high electronic conductivity, fast ion transport capability, and strong polysulfide affinity are introduced to sulfur cathode. Unlike most previous inactive hosts with a fixed affinity or catalytic ability toward LiPSs, the reaction involving Mo₆S₈ is intercalative and the adsorbability for LiPSs as well as the ionic conductivity can be dynamically enhanced via reversible electrochemical lithiation of Mo₆S₈ to Li-ion intercalated Li_xMo₆S₈, thereby suppressing the shuttling effect and accelerating the conversion kinetics. Consequently, the Mo₆S₈ nanosheets act as an effective dynamic-phase promoter in Li–S batteries and exhibit superior cycling stability, high-rate capability, and low-temperature performance. This study opens a new avenue for the development of advanced hosts with dynamic regulation activity for high performance Li-S batteries.     

1T-WS2 Nanosheet-Modified Biomass Carbon as Sulfur Host for High-Performance Lithium–Sulfur Batteries

The sluggish sulfur reaction kinetics and fast capacity attenuation still pose great challenges to lithium–sulfur (Li–S) batteries. Herein, tubular carbonl (HPOC) is obtained by carbonization of the cattail fiber. 1T-WS₂@HPOC is prepared by solvothermal method, and their sulfur composite, 1T-WS₂@HPOC/S and HPOC/S as sulfur host composite, is obtained by sulfur melting. The composite materials are characterized by scanning electron microscopy, X-ray diffraction, thermogravimetry, X-ray photoelectron spectroscopy, etc. Results show that 1T-WS₂ grows uniformly on the HPOC substrate and has abundant active sites, which can effectively improve the physicochemical adsorption capacity of S-fixation (76 wt%) and polysulfide. Battery assembly and electrochemical performance tests are conducted for the HPOC/S and 1T-WS₂@HPOC/S composites. Results show that the initial discharge capacity of the 1T-WS₂@HPOC/S positive electrode is 1272 mAh g⁻¹ at 0.1 C, higher than the HPOC/S positive electrode (1025 mAh g⁻¹). 1T-WS₂@HPOC/S maintains a discharge capacity of 695 mAh g⁻¹ after 500 cycles at 0.5 C, with a capacity decay rate of only 0.054% per cycle. With a discharge capacity of 504 mAh g⁻¹ after 400 cycles at 1 C, the Coulomb efficiency is 98.9%. The 1T-WS₂@HPOC/S composites with unique structure and excellent electrochemical performance have broad application prospects in the field of Li–S batteries.     

Insight into Accelerating Polysulfides Redox Kinetics by BN@MXene Heterostructure for Li–S Batteries

Sluggish redox kinetics and shuttle effect of polysulfides hinder the extensive application of the lithium–sulfur batteries (LSBs). Herein a functional heterostructure of boron nitride (BN) and MXene with an alternately layered structure (BN@MXene) is designed as separator interlayer. High efficiency Li⁺ transmission, uniform lithium deposition, strong adsorption, and efficient catalytic conversion activities of lithium polysulfides (LiPSs) realized by this heterostructure are confirmed by experiments and theoretical calculations. The alternately layered structure provides unblocked ion transmission channels and abundant active sites to accelerate the polysulfides redox kinetics with reduced energy barriers of oxidation and reduction reactions. As a result, the LSBs deliver an initial discharge capacity of up to 1273.9 mAh g⁻¹ at 0.2 °C and a low decay of 0.058% per cycle in long-term cycling up to 700 cycles at 1 °C. This work provides an effective designing strategy to accelerate the polysulfides redox kinetics for advanced Li–S electrochemical system.