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[Display omitted] • A stable double shell of S@MnO 2 @MXene is applied in Li-S batteries. • The loading mass of sulfur can be regulated to 5.88 mg cm−2. • The MnO 2 @MXene composite material can accelerate the adsorption and catalytic conversion of LiPSs. • The cathode with high sulfur loading mass exhibits excellent cyclic stability. Lithium-sulfur (Li-S) batteries represent the most promising next-generation energy storage systems because of their high theoretical specific capacity and energy density. However, the severe shuttle effect and volume expansion of sulfur cathodes have impeded their commercial viability. Hence, accelerating the conversion of lithium polysulfides (LiPSs) is crucial for achieving efficient Li-S batteries. In this study, we employ a straightforward electrostatic self-assembly method to coat ultra-thin MXene nanosheets onto a S@MnO 2 core–shell structure, resulting in a highly conductive three-dimensional network. This unique structure not only suppresses the diffusion of LiPSs but also accelerates electron and ion transfer, ensuring a rapid and efficient conversion of LiPSs. The CV curves of symmetrical cells and the Li 2 S deposition curves demonstrate a significant improvement in the catalytic performance of batteries with S@MnO 2 @MXene. The capacity of Li-S batteries achieved an impressive 842 mAh/g at the current density of 1C, with a minimal capacity decay of only 0.84 mAh/g per cycle within 500 cycles. Additionally, increasing the sulfur loading mass to 5.88 mg cm−2 resulted in an areal capacity of 6.33 mAh cm−2, demonstrating practical application potential. [ABSTRACT FROM AUTHOR]

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Lithium‐sulfur (Li‐S) batteries offer promising prospects due to their high energy density and cost‐effectiveness. However, the sluggish kinetics of lithium polysulfides (LiPSs) conversion, particularly the crucial stage from LiPSs to lithium sulfide (Li2S), hampers their development. Herein, a novel strategy for dynamically regulating LiPSs conversion by incorporating 4‐mercaptopyridine (4Mpy), as a LiPSs Redox Regulator (RR) in the electrolyte is introduced. This organic sulfur additive actively interacts with LiPSs during discharge, facilitating rapid conversion and promoting the formation of a three‐dimensional (3D) Li2S structure, thereby enhancing reaction kinetics. Both theoretical and experimental results reveal that the redox conversion mechanism with the 4Mpy additive differs from traditional electrolytes. Upon lithiation, 4Mpy forms lithium‐pyridinethiolate (Li‐pyS), which reversibly engages in the LiPSs conversion during the charging/discharging cycles, significantly improving the redox process. As a result, the Li‐S battery with 4Mpy additive demonstrates superior performances, achieving 10.05 mAh cm−2 under a high sulfur loading of 10.88 mg cm−2, surpassing industrial benchmarks. This study not only presents an approach to mitigating the shuttle effect in Li‐S batteries but also offers valuable insights into electrolyte design for other metal batteries. [ABSTRACT FROM AUTHOR]

The dendrite growth and volume expansion of the Li metal anode, as well as the LiPSs “shuttle effect” and slow conversion kinetics of the S cathode, have severely hampered the large‐scale development of LSBs. Herein, a simple hydrothermal method is employed to synthesize rod‐like AgVO3, which is then used as the Li metal anode current collector and the separator modification, respectively. As the Li metal anode current collector, AgVO3 has a strong Li affinity, which can lower Li nucleation overpotential and guide uniform deposition of Li metal. The AgVO3‐modified separator can accelerate the redox kinetics of LiPSs and achieve the anchoring of LiPSs. The results of DFT calculation and experiments reveal that the AgVO3 enable the Ag horizontal d orbitals (dxy/dx2‐y2) to hybridize with the S p orbital to form additional σ/σ* and π/π*. The activation of horizontal d orbitals can increase LiPSs anchoring ability, reduce the reaction barrier, and accelerate LiPSs transformation. Hence, the LSBs assembled with the Li@AgVO3 anode and AgVO3 modified separator show excellent cycle performance. This work gives a novel idea for the application of high catalytic performance materials represented by AgVO3, and its unique catalytic performance can successfully achieve LSBs with high performance. [ABSTRACT FROM AUTHOR]

Electrolyte additives have been promising strategies aimed at lithium metal dendrite growth and active materials loss of sulfur cathode those have troubled the development of Li‐S batteries (LSBs), while current interface modulations of electrodes are still challenged by low protection efficiency and high N/P ratio. Herein, potassium 3‐thiophenetrifluoroborate (KPTB) is adopted as an additive to construct versatile interface for both lithium metal anode (LMA) and sulfur cathode. The preferentially electrochemical reduction and oxidation of PTB (3‐thiophenetrifluoroborate) moiety, as well as electrostatic shielding exerted by K+ ion, enable F‐rich solid electrolyte interphase for LMA and construct polythiophene based protection layers on the two electrodes, facilitating fast and uniform ion/electron transfer across the interface, suppressing polysulfide outflow and maintaining integrity of electrodes. Electrochemical measurements indicate that optimized dosage of KPTB in electrolyte remarkably enhances reversibility and cyclic stability of the two electrodes, and endows LSBs with excellent performances over wide temperature range (−25–50 °C). Remarkably, the Li‐S full cells using a 75 µm of LMA can deliver a capacity of 6.0 mAh cm−2 and excellent cyclic performances for 350 cycles, at a N/P ratio as low as 1.4. This work can provide new reliable solution for electrolyte additive based interface protections in LSBs. [ABSTRACT FROM AUTHOR]

Lithium–Sulfur (Li–S) batteries are promising energy storage devices due to their high theoretical energy density. However, challenges such as the shuttling effect and volume expansion have significantly hindered their cycle life and capacity retention. Furthermore, the complex kinetic pathways in Li–S batteries call for advanced characterization techniques to unravel underlying mechanisms. In this study, a hollow porous carbon (HPC) is used as a microreactor, where inverse vulcanization occurs between 1,3‐diisopropylbenzene (DIB) and sulfur (S8), resulting in the creation of three‐dimensionally interconnected and well‐distributed S‐DIB in carbon frameworks. As a result, the dual confinement strategy imparts Li–S coin cells with remarkable cycling stability and capacity retention, exhibiting an impressive capacity of 866 mAh g−1 when returning to 0.1 C after 100 cycles of rate capability tests. Particularly, the Energy‐selective Backscattered (EsB) assisted Scanning Electron Microscope (SEM) technique as a novel approach is introduced to distinguish different lengths of polysulfides. Their distribution is visualized in the cross‐section view of the electrode in a micrometer range. These EsB images provide concrete indications of the sulfur evolution process and explain the capacity degradation during cycling. [ABSTRACT FROM AUTHOR]

Cooperative catalysis is a promising approach to enhance the sluggish redox kinetics of lithium polysulfides (LiPSs) for practical lithium–sulfur (Li–S) batteries. However, the elusory synergistic effect among multiple active sites makes it challenging to accurately customize the electronic structure of catalysts. Herein, a strategy of precisely tailoring eg orbitals of spinel oxides through chemomechanics engineering is porposed to regulate LiPSs retention and catalysis. By manipulating the regulable cations in MnxCo3‐xO4, it is theoretically and experimentally revealed that the lattice strain induced by the Jahn–Teller active and high‐spin Mn3+ at octahedral (Oh) sites can increase the eg occupancy of low‐spin Co3+Oh, which effectively regulates the chemical affinity toward LiPSs and establishes an unblocked channel for intrinsic charge transfer. This leads to a volcano‐type correlation between the eg occupancy at Oh sites and sulfur redox activity. Benefitting from the cooperative catalysis of dual‐active sites, MnCo2O4 with an average eg occupancy of 0.45 affords the most appropriate adsorption strength and rapid redox kinetics toward LiPSs, leading to remarkable rate performance and capacity retention for the assembled Li–S batteries. This work demonstrates the promise of chemomechanics engineering for optimizing the eg occupancy to achieve efficient sulfur redox catalysts. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li–S) batteries are a highly promising energy storage system due to their ultra-high theoretical energy density. However, Li–S batteries, based on the dissolved deposition mechanism, suffer from lithium polysulfides (LiPSs) shuttling and slow conversion kinetics, causing severe capacity decay during operation. Herein, we have improved the battery life by a LiPSs adsorption-rapid catalytic conversion Fe2O3@C catalyst in the modified separator. The Fe2O3@C modified separator first physically restricts LiPSs and then rapidly converts the captured LiPSs through the polar adsorption and catalytic ability of Fe2O3, greatly promoting the LiPS conversion kinetics in Li–S batteries. The battery with Fe2O3@C exhibits excellent electrochemical performance. In detail, the initial discharge specific capacity of the first discharge is 1043.26 mAh g−1 at 0.05 C; the specific capacity is maintained at 676.80 mAh g−1 after 100 cycles at 0.2 C. The high specific capacity of 389.3 mAh g−1 is maintained even after 1000 cycles with a capacity decay of 0.055% per cycle. This work provides a way to improve sulfur conversion kinetics through metal oxides. [ABSTRACT FROM AUTHOR]

The applications of lithium (Li)–sulfur (S) batteries are simultaneously hampered by the unlimited dendritic Li growth and the sluggish redox kinetics of polysulfides (LiPSs). In this work, an electronic state‐modulated Ni4N/Zn3N2 heterogeneous nanosheet arrays is painstakingly fabricated on the surface of carbon cloth (CC@Ni4N/Zn3N2) as an efficient bi‐service host to promote uniform Li deposition and boost efficient LiPSs catalysis. It is found that the electronic structure of Ni4N/Zn3N2 heterostructure is modulated to realize a rational transition metal d‐band center, and its built‐in electric field (BIEF) within the heterointerfaces facilitates the interfacial charge transfer, resulting in low Li deposition/migration energy barrier and efficient LiPSs adsorption/catalytic conversion kinetics. As a result, the as‐prepared CC@Ni4N/Zn3N2‐Li anode can enable the Li||Li symmetrical cells to possess a long‐term lifespan over 500 h even at 10 mA cm−2/20 mAh cm−2, and the as‐assembled LiNi0.8Co0.1Mn0.1O2||CC@Ni4N/Zn3N2‐Li full cell also shows an excellent cycling performance (95.8% capacity retention after 100 cycles). When used for both S and Li loading, the as‐assembled CC@Ni4N/Zn3N2‐S||CC@Ni4N/Zn3N2‐Li full cell exhibits an outstanding cycling stability (744 mAh g−1 after 1000 cycles at 2C). This work highlights the great potential of heterostructures for fabricating ideal bi‐serve hosts for both Li and S electrodes. [ABSTRACT FROM AUTHOR]

[Display omitted] The high theoretical energy density and specific capacity of lithium-sulfur (Li-S) batteries have garnered considerable attention in the prospective market. However, ongoing research on Li-S batteries appears to have encountered a bottleneck, with unresolved key technical challenges such as the significant shuttle effect and sluggish reaction kinetics. This investigation explores the catalytic efficacy of three catalysts for Li-S batteries and elucidates the correlation between their structure and catalytic impacts. The results suggest that the combined utilization of lithium-insertion technology and a proton exchange approach for δ-MnO 2 can optimize its electronic structure, resulting in an optimal catalyst (H/Li inserted δ-MnO 2 , denoted as HLM) for the sulfur reduction reaction. The replacement of Mn sites in δ-MnO 2 with Li atoms can enhance the structural stability of the catalyst, while the introduction of H atoms between transition metal layers contributes to the satisfactory catalytic performance of HLM. Theoretical calculations demonstrate that the bond length of Li 2 S 4 adsorbed by the HLM molecule is elongated, thereby facilitating the dissociation process of Li 2 S 4 and enhancing the reaction kinetics in Li-S batteries. Consequently, the Li-S battery utilizing HLM as a catalyst achieves a high areal specific capacity of 4.2 mAh cm−2 with a sulfur loading of 4.1 mg cm−2 and a low electrolyte/sulfur (E/S) ratio of 8 μL mg−1. This study introduces a methodology for designing effective catalysts that could significantly advance practical developments in Li-S battery technology. [ABSTRACT FROM AUTHOR]

Due to the limitations of the raw materials and processes involved, polyolefin separators used in commercial lithium‐ion batteries (LIBs) have gradually failed to meet the increasing requirements of high‐end batteries in terms of energy density, power density, and safety. Hence, it is very important to develop next‐generation separators for advanced lithium (Li)‐based rechargeable batteries including LIBs and Li–S batteries. Nonwoven nanofiber membranes fabricated via electrospinning technology are highly attractive candidates for high‐end separators due to their simple processes, low‐cost equipment, controllable microporous structure, wide material applicability, and availability of multiple functions. In this review, the electrospinning technologies for separators are reviewed in terms of devices, process and environment, and polymer solution systems. Furthermore, strategies toward the improvement of electrospun separators in advanced LIBs and Li–S batteries are presented in terms of the compositions and the structure of nanofibers and separators. Finally, the challenges and prospects of electrospun separators in both academia and industry are proposed. We anticipate that these systematic discussions can provide information in terms of commercial applications of electrospun separators and offer new perspectives for the design of functional electrospun separators for advanced Li‐based batteries. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries hold the potential to revolutionize energy storage due to the high theoretical capacity and energy density. However, the commercialization process is seriously hindered by the rapid capacity decay and low utilization of sulfur, caused by the inevitable slow dynamics and the "shuttle effect". The incorporation of metal-based electrocatalysts into sulfur cathodes shows promise in promoting the conversion of lithium polysulfides (LiPSs), reducing the "shuttle effect", and enhancing cell kinetics and cycle life. Among these, Fe-based materials, characterized by environmental friendliness, low cost, abundant reserves, and high activity, are extensively used in sulfur cathode modification. This article reviews the advancements of Fe-based materials in enhancing Li-S batteries in recent years. Starting from single/multi-component Fe-based metal compounds and single/bimetallic atoms, the influence of different Fe coordination environments on the conversion mechanism of LiPSs is analyzed. It is hoped that this review and the proposed prospects can further stimulate the development and application of the Fe element in Li-S batteries in the future. [ABSTRACT FROM AUTHOR]

Although Li–S batteries have a high theoretical capacity, their application are significantly hindered by the complex shuttle effect of polysulfides. To address the issues, in this paper, Ni2V2O7 prepared by a simple method is proposed as an efficient catalyst for S cathodes. Ni2V2O7 composed of Ni–O octahedra and V–O tetrahedra has a specific electronic structure. The Ni and V atoms interacted, enabling a fast kinetics of polysulfide redox. Moreover, Ni2V2O7 contains metal sites (Ni and V) and oxygen vacancies, providing a high adsorption capacity and abundant active sites for polysulfide redox. Therefore, Li–S batteries consisting of Ni2V2O7-based cathodes exhibit an excellent cycling stability with a capacity of 1061 mAh g−1 and capacity retention of 87.6% after 150 cycles at 0.2 C. Moreover, at 1 C rate, the batteries exhibit a capacity of 706 mAh g−1 after 300 cycles with a minimal capacity decay of only 0.08% per cycle.

[Display omitted] Lithium-sulfur batteries (LSBs) have been increasingly recognized as a promising candidate for the next-generation energy-storage systems. This is primarily because LSBs demonstrate an unparalleled theoretical capacity and energy density far exceeding conventional lithium-ion batteries. However, the sluggish redox kinetics and formidable dissolution of polysulfides lead to poor sulfur utilization, serious polarization issues, and cyclic instability. Herein, sulfiphilic few-layer MoSSe nanoflake decorated on graphene (MoSSe@graphene), a two-dimensional and catalytically active hetero-structure composite, was prepared through a facile microwave method, which was used as a conceptually new sulfur host and served as an interfacial kinetic accelerator for LSBs. Specifically, this sulfiphilic MoSSe nanoflake not only strongly interacts with soluble polysulfides but also dynamically promotes polysulfide redox reactions. In addition, the 2D graphene nanosheets can provide an extra physical barrier to mitigate the diffusion of lithium polysulfides and enable much more uniform sulfur distribution, thus dramatically inhibiting polysulfides shuttling meanwhile accelerating sulfur conversion reactions. As a result, the cells with MoSSe@graphene nanohybrid achieved a superior rate performance (1091 mAh/g at 1C) and an ultralow decaying rate of 0.040 % per cycle after 1000 cycles at 1C. [ABSTRACT FROM AUTHOR]

[Display omitted] • The TpPa-SO 3 Li is firstly designed as Li+ pump for PEO-based solid electrolyte. • The Li/Li symmetric cell with PEO/5% TpPa-SO 3 Li can stably cycle for 1300 h. • Assembled all-solid-state Li-S cells can stably cycle for 600 cycles at 60 °C. Poly(ethylene oxide) (PEO)-based electrolytes are widely used for building solid-state lithium–sulfur (Li–S) batteries but suffer from poor lithium-ion (Li+) transportation kinetics. Here, a lithium-sulfonated covalent organic framework (TpPa-SO 3 Li) was synthesized and functionalized as a Li+ pump in a PEO-based solid-state electrolyte to fabricate robust Li–S batteries. The designed TpPa-SO 3 , Li with its porous skeleton and abundant lithium sulfonate groups not only provided iontransport channels but also enhanced the fast migration of Li+. The PEO composite electrolyte containing 5 %-TpPa-SO 3 Li exhibited a notable ionic conductivity of 6.28 × 10−4 S cm−1 and an impressive Li+ transference number of 0.78 at 60 °C. As a result, Li–Li symmetric batteries with the optimized PEO/TpPa-SO 3 Li composite electrolyte stably cycled for 300 h, with a minimal overpotential of only 100 mV at 0.5 mA cm−2. Moreover, the customized solid-state Li–S batteries based on PEO/TpPa-SO 3 Li were stable for 600 cycles at 60 oC with a high Coulombic efficiency of approximately 98 %. This study provides a promising strategy for introducing covalent-organic-framework (COF)-based Li+ pumps to build robust solid-state Li–S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Lithium-sulfur (Li-S) batteries have garnered extensive research interest as one of the most promising energy storage devices due to their ultra-high theoretical energy density. However, the sluggish reaction kinetics, abominable shuttling effect and inferior cycling stability severely restrict its practical application. Herein, a multifunctional CoP/Co@NC/CNT heterostructure host material was elaborately designed and synthesized by integrating CoP/Co heterojunction, N -doped carbon hollow polyhedrons (NC) and carbon nanotubes (CNTs). Specifically, the CoP/Co heterojunction can reconfigure the local electronic structure, resulting in a synergistic effect that enhances adsorption capacity and catalytic activity compared to CoP and Co alone. Furthermore, the CNTs-grafted NC not only provides multi-dimensional pathways for rapid electron transport and ion diffusion, but also physically restricts the diffusion of polysulfides during charge-discharge processes. Owing to these advantages, the battery assembled with the CoP/Co@NC/CNT/S cathode yields an impressive discharge specific capacity of 1479.9 mAh g−1 at 0.1C, and excellent capacity retention of 793.7 mAh g−1 over 500 cycles at 2C (∼85.5 % of initial capacity). The rational integration of multifunctional heterostructures could provide an effective strategy for designing high-efficiency nanocomposite electrocatalysts to promote sulfur redox kinetics in Li-S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Successful preparation of cathode materials through doping and interface engineering has enhanced Li–S battery performance synergistically. • Nitrogen-nickel co-doped MXene nanosheets were employed as a conductive framework to successfully in-situ synthesize a TiO 2 homojunction structure containing both anatase and rutile phases. • Employing an in-situ transmission electron microscopy (TEM) technique allowed us to observe the growth process of the homojunction for the first time, revealing its temperature-dependent behavior. • The assembled ART@NNM cathode in the Li–S cell exhibits outstanding performance, effectively alleviating shuttle effects and promoting sulfur conversion reactions. The commercialization of lithium-sulfur (Li–S) batteries has faced challenges due to the shuttle effect of soluble intermediate polysulfides and the sluggish kinetics of sulfur redox reactions. In this study, a synergistic catalyst medium was developed as a high-performance sulfur cathode material for Li–S batteries. Termed A/R-TiO 2 @ Ni-N-MXene, this sulfur cathode material features an in-situ derived anatase–rutile homojunction of TiO 2 nanoparticles on Ni-N dual-atom-doped MXene nanosheets. Using in-situ transmission electron microscopy (TEM) technique, we observed the growth process of the homojunction for the first time confirming that homojunctions facilitated charge transfer, while dual-atom doping offered abundant active sites for anchoring and converting soluble polysulfides. Theoretical calculations and experiments showed that these synergistic effects effectively mitigated the shuttle effect, leading to improved cycling performance of Li–S batteries. After 500 cycles at a 1C rate, Li–S batteries using A/R-TiO 2 @Ni-N-MXene as cathode materials exhibited stable and highly reversible capacity with a capacity decay of only 0.056 % per cycle. Even after 150 cycles at a 0.1C rate, a high-capacity retention rate of 62.8 % was achieved. Additionally, efficient sulfur utilization was observed, with 1280.76 mA h/g at 0.1C, 694.24 mA h/g at 1C, alongside a sulfur loading of 1.5–2 mg/cm2. The effective strategy based on homojunctions showcases promise for designing high-performance Li–S batteries. [ABSTRACT FROM AUTHOR]

Abstract Coal pitch, an important by-product in the coal coking industry with a high output, is a low-cost and high-carbon yield precursor for the manufacturing of high-value carbon materials. Herein, N/O co-doped carbon fiber (CFCP), fabricated by electrospinning using pre-oxidized coal pitch as the precursor, was employed as the sulfur host for Li-S batteries. The presence of more pyrrolic N and graphic N in CFCP than carbon fiber made from polyacrylonitrile benefits the adsorption of lithium polysulfide and the battery’s life. Sulphur-CFCP cathode (S@CFCP) exhibited excellent specific capacity and cyclability, with a specific capacity of 701.1 mAh/g and a low capacity decay rate of 0.088% per cycle over 200 cycles at 2.0 C, respectively. The high ion diffusion rate, low charge transfer resistance, and effective conversion of lithium polysulfides enable the high electrochemical performance of S@CFCP.

Lithium–sulfur (Li–S) battery with high theoretical capacity and high energy density is considered to be a best alternative of Li‐ion battery. However, challenges associated with Li–S batteries are yet to be addressed effectively to enable their commercialization. Uncontrolled shuttling of polysulfides causes rapid capacity decay and low discharge capacity of the battery cell. To address such shuttling effect related to the polysulfide movement, nano‐TiO2‐grafted carbon sheet interlayer is introduced. Proposed material is synthesized by the combined sol–gel and hydrothermal processes. Rietveld analysis is done for the determination of phase(s) present in the material. These are anatase and rutile phases. Scanning and transmission microscopic studies reveal the morphological features of prepared material. Quantitative study of prepared material for its constituents is done by thermogravimetry analysis, which confirms the presence of 83% TiO2. An interlayer of 16 mm diameter is punched out and incorporated in a coin cell assembly. Cell assembled with interlayer shows superior electrochemical performance with initial discharge capacity of 839 mAh g−1 at 0.2 C rate and 63% capacity retention till 100th cycle. Diffusion studies reveal that insertion of interlayer controls the reaction kinetics and supports polar–polar interaction between interlayer and polysulfides. [ABSTRACT FROM AUTHOR]

[Display omitted] The commercial application of lithium-sulfur batteries is primarily impeded by the constant shuttling of soluble polysulfides and sluggish redox kinetics. Nowadays, the discovery of the heterojunction, which combines materials with diverse properties, offers a new perspective for overcoming these obstacles. Herein, a functional coating separator for the lithium-sulfur battery is designed using a MnO 2 -ZnS p-n heterojunction with a spontaneous built-in electric field (BIEF). The MnO 2 nanowire provides suitable adsorption capacity for polysulfides, while the abundant reactive sites brought by ZnS ensure efficient conversion. Moreover, the BIEF significantly facilitates the migration of electrons and polysulfides at the MnO 2 -ZnS interface, enabling a smooth "adsorption-diffusion-conversion" reaction mechanism. By serving as both the adsorption module and catalytic sites, this BIEF allows batteries utilizing separators modified with MnO 2 -ZnS heterojunction to achieve an impressive initial capacity of 1511.1 mAh g−1 at 0.1C and maintain a capacity decay rate of merely 0.048% per cycle at 2.0C after 1000 cycles. Even when increasing sulfur loading to 9.4 mg cm−2 in lean electrolyte (5.4 μL mg−1), the battery still exhibits an ultrahigh areal capacity of 6.0 mAh cm−2 after 100 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] The practical application of lithium–sulfur (Li–S) batteries is inhibited by the shuttle effect of lithium polysulfides (LiPSs) and slow polysulfide redox kinetics on the S cathode as well as the uncontrollable growth of dendrites on the Li metal anode. Therefore, both cathode and anode sides must be considered when modifying Li−S batteries. Herein, two-dimensional (2D) ultrathin CoSe 2 nanobelts are in situ grown on 2D N-doped MXene nanosheets (CoSe 2 @N-MXene) via one-step solvothermal process for the first time. Owing to its unique 2D/2D structure, CoSe 2 @N-MXene can be processed to crumpled nanosheets by freeze-drying and flexible and freestanding films by vacuum filtration. These crumpled CoSe 2 @N-MXene nanosheets with abundant active sites and inner spaces can act as S hosts to accelerate polysulfide redox kinetics and suppress the shuttle effect of LiPSs owing to their strong adsorption ability and catalytic conversion effect with LiPSs. Meanwhile, the CoSe 2 @N-MXene film (CoSe 2 @NMF) can act as a current collector to promote uniform Li deposition because it contains lithiophilic CoSe 2 and N sites. Under the systematic effect of CoSe 2 @N-MXene on S cathode and Li metal anode, the electrochemical and safety performance of Li–S batteries are improved. CoSe 2 @NMF also shows excellent storage performances in flexible energy storage devices. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur (Li‐S) batteries are considered a competitive next‐generation electrochemical energy storage device, while the shuttle effect of soluble lithium polysulfides (LiPSs) resulting from the sluggish redox kinetics severely impedes their practical applications. Herein, a novel cation doping strategy is demonstrated for substantially accelerating the sulfur redox kinetics on the transition metal sulfide (TMS) electrocatalysts by partially substituting cobalt atoms with in situ dissolved Ni dopants (NixCo3‐xS4, 0

Lithium–sulfur batteries (LSBs) are widely regarded as promising next‐generation batteries due to their high theoretical specific capacity and low material cost. However, the practical applications of LSBs are limited by the shuttle effect of lithium polysulfides (LiPSs), electronic insulation of charge and discharge products, and slow LiPSs conversion reaction kinetics. Accordingly, the introduction of catalysts into LSBs is one of the effective strategy to solve the issues of the sluggished LiPS conversion. Because of their nearly 100% atom utilization and high electrocatalytic activity, single‐atom catalysts (SACs) have been widely used as reaction mediators for LSBs' reactions. Excitingly, the SACs with asymmetric coordination structures have exhibited intriguing electronic structures and superior catalytic activities when compared to the traditional M–N4 active sites. In this review, we systematically describe the recent advancements in the installation of asymmetrically coordinated single‐atom structure as reactions catalysts in LSBs, including asymmetrically nitrogen coordinated SACs, heteroatom coordinated SACs, support effective asymmetrically coordinated SACs, and bimetallic coordinated SACs. Particularly noteworthy is the discussion of the catalytic conversion mechanism of LiPSs spanning asymmetrically coordinated SACs. Finally, a perspective on the future developments of asymmetrically coordinated SACs in LSB applications is provided. [ABSTRACT FROM AUTHOR]

Rechargeable lithium–sulfur (Li–S) batteries, featuring high energy density, low cost, and environmental friendliness, have been dubbed as one of the most promising candidates to replace current commercial rechargeable Li‐ion batteries. However, their practical deployment has long been plagued by the infamous "shuttle effect" of soluble Li polysulfides (LiPSs) and the rampant growth of Li dendrites. Therefore, it is important to specifically elucidate the solvation structure in the Li–S system and systematically summarize the feasibility strategies that can simultaneously suppress the shuttle effect and the growth of Li dendrites for practical applications. This review attempts to achieve this goal. In this review, we first introduce the importance of developing Li–S batteries and highlight the key challenges. Then, we revisit the working principles of Li–S batteries and underscore the fundamental understanding of LiPSs. Next, we summarize some representative characterization techniques and theoretical calculations applied to characterize the solvation structure of LiPSs. Afterward, we overview feasible designing strategies that can simultaneously suppress the shuttle effect of soluble LiPSs and the growth of Li dendrites. Finally, we conclude and propose personal insights and perspectives on the future development of Li–S batteries. We envisage that this timely review can provide some inspiration to build better Li–S batteries for promoting practical applications. [ABSTRACT FROM AUTHOR]

Batteries that utilize low‐cost elemental sulfur and light metallic lithium as electrodes have great potential in achieving high energy density. However, building a lithium–sulfur (Li–S) full battery by controlling the electrolyte volume generally produces low practical energy because of the limited electrochemical Li–S redox. Herein, the high energy/high performance of a Li–S full battery with practical sulfur loading and minimum electrolyte volume is reported. A unique hybrid architecture configured with Ni–Co metal alloy (NiCo) and metal oxide (NiCoO2) nanoparticles heterogeneously anchored in carbon nanotube‐embedded self‐standing carbon matrix is fabricated as a host for sulfur. This work demonstrates the considerable improvement that the hybrid structure's high conductivity and satisfactory porosity promote the transport of electrons and lithium ions in Li–S batteries. Through experimental and theoretical validations, the function of NiCo and NiCoO2 nanoparticles as an efficient polysulfide mediator is established. These particles afford polysulfide anchoring and catalytic sites for Li–S redox reaction, thus improving the redox conversion reversibility. Even at high sulfur loading, the nanostructured Ni–Co metal alloy and metal oxide enable to have stable cycling performance under lean electrolyte conditions both in half‐cell and full‐cell batteries using a graphite anode. [ABSTRACT FROM AUTHOR]

Carbon cloth (CC) possesses great potential as a sulfur host because of its excellent conductivity, flexibility, and easily modified free‐standing structure. However, the previous works do not take full advantage of CC except for the role of support and current collector. The smooth surface, small specific surface area, and poor binding force between coating materials and CC matrix are unfavorable for loading coating materials. The slow redox kinetics and low sulfur loading of sulfur cathodes still seriously restrict the development of Lithium–Sulfur (Li–S) batteries. Herein, the porous carbon cloth loading cobalt selenide (PCC@CoSe2) is constructed as an integrated sulfur host through a pore‐creating and selenylation strategy. The pore‐creating engineering greatly optimizes the 3D pore structure of CC to raise the sulfur and catalyst loading and provides enough space to accommodate the volume change of sulfur species. In addition, CoSe2 particles as nano‐catalyst units embedded in PCC can effectively adsorb‐catalyze polysulfides and improve the reaction kinetics. The resulting integrated sulfur cathode has realized the high‐efficiency polysulfide catalytic conversion and fast lithium ion migration, significantly enhancing redox kinetics and sulfur loading. [ABSTRACT FROM AUTHOR]

Intensive increases in electrical energy storage are being driven by electric vehicles (EVs), smart grids, intermittent renewable energy, and decarbonization of the energy economy. Advanced lithium–sulfur batteries (LSBs) are among the most promising candidates, especially for EVs and grid-scale energy storage applications. In this topical review, the recent progress and perspectives of practical LSBs are reviewed and discussed; the challenges and solutions for these LSBs are analyzed and proposed for future practical and large-scale energy storage applications. Major challenges for the shuttle effect, reaction kinetics, and anodes are specifically addressed, and solutions are provided on the basis of recent progress in electrodes, electrolytes, binders, interlayers, conductivity, electrocatalysis, artificial SEI layers, etc. The characterization strategies (including in situ ones) and practical parameters (e.g., cost-effectiveness, battery management/modeling, environmental adaptability) are assessed for crucial automotive/stationary large-scale energy storage applications (i.e., EVs and grid energy storage). This topical review will give insights into the future development of promising Li–S batteries toward practical applications, including EVs and grid storage. [ABSTRACT FROM AUTHOR]

Li–S batteries are positioned as a strong alternative for efficient energy storage due to their high theoretical energy density and their theoretical specific capacity (1675 mA h g−1) compared to current Li-ion batteries; however, their commercialization is affected by the rapid decay of the specific capacity as a consequence of the different species of lithium polysulfides that are generated during the charge–discharge processes. The use of nitrogen-doped mesoporous carbon materials has been shown to have the ability to confer electronic conductivity to sulfur and retain the lithium polysulfide species. However, there are not enough studies to help understand how the type of nitrogen precursor influences the development of specific nitrogen functionalities to favor the retention of lithium polysulfide species. This work seeks to determine the effect of the use of different nitrogen precursors on the structural changes of the mesoporous carbon materials prepared, and thus evaluate the electrochemical behavior of Li–S cells correlating the type of nitrogen functionality generated when the precursor is variated with the charge/discharge capacity developed during the cell operation. For this study, different carbon materials were prepared by the variation of the nitrogen source (melamine, ethylenediamine, and hexadecylamine) to obtain a N-doped mesoporous carbon with different distributions of nitrogen functionalities in its structure. The use of the primary amine ethylenediamine as a nitrogen precursor in the formation of structured carbon materials favored elemental sulfur infiltration into its pores, resulting in the maximum sulfur content within the pores and interacting with the carbonaceous matrix (78.8 wt.%). The carbon material prepared with this precursor resulted in a higher content of N-pyridinic functionality, which, combined with the high content of N-pyrrolic, resulted in the highest specific discharge capacity at 0.1 C after 100 cycles when compared to cells assembled with materials derived from the use of melamine and hexadecylamine precursors. The cell assembled with the electrode formed from ethylenediamine as a nitrogen precursor presented an initial discharge capacity of 918 mA h g−1 with a Coulombic efficiency of ~83.4% at 0.1 C after 100 cycles. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries have been considered as promising energy storage systems due to the merits of high energy density and low cost. However, the lithium polysulfides (LiPSs) diffusion and sluggish redox kinetics hamper the battery performance. In this work, low-bandgap indium oxide (In2O3) with dense oxygen vacancies (In2O3−x, 0 < x < 3) confined in nitrogen-doped carbon column (NC) is developed as a desirable LiPSs immobilizer and promoter to address these intractable problems. The NC confined In2O3−x with rich O vacancies (In2O3−x@NC) lowers the bandgap of 1.78 eV, strengthens the chemical adsorbability to LiPSs, and catalyzes the bidirectional Li2S redox. Attributed to the structural and chemical cooperativities, the obtained sulfur electrodes exhibit a stable cycling over 550 cycles at 1.0 C and splendid rate capability up to 4.0 C. More significantly, when the sulfur-loading reaches as high as 5.5 mg·cm−2, the cathodes achieve an areal capacity of 5.12 mAh·cm−2 at 0.1 C. The strategy of NC confined catalyst with rich defects engineering demonstrates great promise in the development of practical Li–S batteries. [ABSTRACT FROM AUTHOR]

Abstract Due to the limitations of the raw materials and processes involved, polyolefin separators used in commercial lithium‐ion batteries (LIBs) have gradually failed to meet the increasing requirements of high‐end batteries in terms of energy density, power density, and safety. Hence, it is very important to develop next‐generation separators for advanced lithium (Li)‐based rechargeable batteries including LIBs and Li–S batteries. Nonwoven nanofiber membranes fabricated via electrospinning technology are highly attractive candidates for high‐end separators due to their simple processes, low‐cost equipment, controllable microporous structure, wide material applicability, and availability of multiple functions. In this review, the electrospinning technologies for separators are reviewed in terms of devices, process and environment, and polymer solution systems. Furthermore, strategies toward the improvement of electrospun separators in advanced LIBs and Li–S batteries are presented in terms of the compositions and the structure of nanofibers and separators. Finally, the challenges and prospects of electrospun separators in both academia and industry are proposed. We anticipate that these systematic discussions can provide information in terms of commercial applications of electrospun separators and offer new perspectives for the design of functional electrospun separators for advanced Li‐based batteries.

[Display omitted] Two-dimensional (2D) transition metal carbide and nitride (MXenes) and 2D transition metal borides are analogs to MXenes and are given the name MBenes. MXenes and MBenes are important 2D nanomaterials with diverse potential in various research domains of physics and chemistry. MBenes offer high conductivity, flexibility, and mechanical properties, attracting attention for energy storage applications such as mono/divalent batteries and supercapacitors. Both theoretical and experimental results confirmed the exciting potential of MBene for energy storage applications. MBenes have demonstrated a broad range of fascinating characteristics and have been extensively researched for their potential uses in energy storage and conversion devices. It is reasonable to anticipate that MBenes will have a bright future. The investigation of MBenes, on the other hand, is still in its early stages, and there are a great deal of expected features and applications that are being investigated. This review aims to provide an overview of recent advancements not only in energy storage applications but also in various other aspects, including synthetic methods, morphological and structural characteristics, and other associated properties of MBene. Finally, this critical review ends with the promising prospects, challenges, and opportunities in MBene advancements. [ABSTRACT FROM AUTHOR]

Elaborate modulation of the highly active crystal facet emerges as an efficient strategy for enhancing the nanocrystalline catalytic activity. Herein, ultrathin TiB2 nanosheets with preferentially exposed (1-10) facets are developed as highly efficient catalyst with enriched bonding and electrocatalytic sites in Li-S batteries. Attributed to the highly equivalent exposure of Ti and B active sites on the (1-10) surface, the (1-10) facet-dominated TiB2 nanosheets maximize the binding effect via Ti and B dual-atom-sites adsorption through Ti--S and B--S bonds. More importantly, experiments and theoretical calculations confirm the superb catalytic activity of (1-10)TiB2 in facilitating the polysulfide conversion and Li2S decomposition, thereby markedly suppressing the shuttling effect and improving the redox kinetics. Consequently, excellent electrochemical properties are achieved in Li-S batteries, which demonstrate a high discharge capacity of 1469 mAh g-1 at 0.2 C and maintain high capacity reversibility at 1 C with a low capacity decay rate of 0.048% over 500 cycles. Even under a sulfur loading of 5 mg cm-2, a prominent areal capacity of 4.86 mAh cm-2 is still attained. It is proposed that the crystal surface engineering provides a new path for the structure optimization of sulfur catalysts in Li-S batteries. [ABSTRACT FROM AUTHOR]

Accelerating catalytic conversion of lithium polysulfides (LiPSs) is a promising way to address the shuttle effect of lithium-sulfur (Li-S) batteries but remains a challenge to date. Herein, a universal metal-organic framework (MOF)-confined strategy is proposed to fabricate atomically dispersed metal catalysts (ADMCs) with the help of ethylenediaminetetraacetic acid (EDTA) toward fast redox conversion in Li-S batteries. In the synthesis, the EDTA acts as not only the coupling agent for the chemical bonding with unsaturated sites of MOF but also the chelating agent for metal ion capture and further confining them into MOF. As a proof of concept, the ADMCs made of transition metal sites anchored on MOF-808 (named MOF-808-M, M = Fe, Co, Ni, Cu, Zn, etc.) are obtained, with well-defined M-N[sub 2]O[sub 2] configurations. The in-depth experiments and theoretical calculations reveal that the atomically dispersed M-N2O2 sites are capable of enhancing the chemical affinity of MOF-808-M toward LiPSs and further accelerating their redox conversion by reducing the energy barrier of the rate-limiting step. As a result, the assembled Li-S batteries with S@MOF-808-M cathode, represented by S@MOF-808-Zn exhibit a high reversible specific capacity of 1192 mAh g-1 at 0.1 C, excellent rate capability of 599 mAh g-1 at 2 C, and remarkable long-term cycling stability with a capacity retention rate of 94.6% after 300 cycles at 1 C. Moreover, the high areal capacity of 4.79 mAh cm-2 at 0.2 C with a sulfur loading of 5.14 mg cm-2 for S@MOF-808-M cathode can be achieved. This work presents a universal strategy to fabricate ADMCs with well-defined active centers by combining the advantages of MOF for Li-S batteries. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries with a high theoretical energy density of 2600 Wh·kg−1 are hindered by challenges such as low S conductivity, the polysulfide shuttle effect, low S reduction conversion rate, and sluggish Li2S oxidation kinetics. Herein, single-atom non-noble metal catalysts (SACs) loaded on two-dimensional (2D) vanadium disulfide (VS2) as the potential host materials for the cathode in Li–S batteries were investigated systematically by using first-principles calculations. Based on the comparisons of structural stability, the ability to immobilize sulfur, electrochemical reactivity, and the kinetics of Li2S oxidation decomposition between these non-noble metal catalysts and noble metal candidates, Nb@VS2 and Ta@VS2 were identified as the potential candidates of SACs with the decomposition energy barriers for Li2S of 0.395 eV (Nb@VS2) and of 0.162 eV (Ta@VS2), respectively. This study also identified an exothermic reaction for Nb@VS2 and the Gibbs free energy of 0.218 eV for Ta@VS2. Furthermore, the adsorption and catalytic mechanisms of the VS2-based SACs in the reactions were elucidated, presenting a universal case demonstrating the use of unconventional graphene-based SACs in Li–S batteries. This study presents a universal surface regulation strategy for transition metal dichalcogenides to enhance their performance as host materials in Li–S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] The high activity barriers of Li 2 S nucleation and deposition limit the redox reaction kinetics of lithium polysulfides (LiPSs), meanwhile, the significant shuttle effect of LiPSs hampers the advancement of Li-S batteries (LSBs). In this work, a NiSe 2 /CoSe 2 -rGO (NiSe 2 /CoSe 2 -G) sulfur host with bifunctional catalytic activity was prepared through a hard template method. Electrochemical experiment results confirm that the combination of NiSe 2 and CoSe 2 not only facilitates the bidirectional catalytic function during charge and discharge processes, but also increases the active sites toward LiPSs adsorption. Simultaneously, the highly conductive rGO network enhances the electronic conductivity of NiSe 2 /CoSe 2 -G/S and provides convenience for loading NiSe 2 /CoSe 2 catalysts. Benefitting from the exceptional catalytic-adsorption capability of NiSe 2 /CoSe 2 and the presence of rGO, the NiSe 2 /CoSe 2 -G/S electrode exhibits excellent electrochemical properties. At 1C, it demonstrates a low capacity attenuation of 0.087 % per cycle during 500 cycles. The electrode can maintain a discharge capacity of 927 mAh/g at a sulfur loading of 3.3 mg cm−2. The bidirectional catalytic activity of NiSe 2 /CoSe 2 -G offers a prospective approach to expedite the redox reactions of active S, meanwhile, this work also offers an ideal approach for designing efficient S hosts for LSBs. [ABSTRACT FROM AUTHOR]

Configuring a carbon substrate with low surface polarity seems very important and significant for accelerating the cathode electrochemical performances of the Lithium-sulfur batteries, which is widely regarded as one of the most promising candidates for the next-generation green energy suppliers. The corn starch-derived carbon with in-situ multi-elements doping, initially carbonized by 6 mol/L H 2 SO 4 and then calcined in nitrogen atmosphere, is employed to configure sulfur cathode for Lithium–Sulfur batteries in this study. As-received carbon with randomly distributed graphical domains serves as charge carriers diffusion channels during discharging/charging cycles, thus endowing the cathode considerable excellent performances. Specifically, the loading amount of sulfur in cathode is around 60.31 wt% and the effective utilization efficiency of active reagent sulfur in cathode is up to 60 %. On activating the cathode at 0.114 A g−1 at 0, 25 and 40 °C, the initial discharge capacities of the Lithium–Sulfur batteries with corn starch-derived carbon-based composite cathode (with ∼1.3 mg cm−2 sulfur) are 278.6, 1023.7 and 976.1 mAh∙g−1, respectively. Accordingly, more uniform, and thinner solid electrolyte interphase membrane formed under room temperature activation, leaving in the dramatically diminished R sur value, contributes to the comparable cycling stability and rate performances of as-designed carbon-based sulfur cathode for Lithium–Sulfur Batteries. [ABSTRACT FROM AUTHOR]

Lithium‐Sulfur (Li‐S) batteries as the next‐generation battery system have an ultrahigh theoretical energy density. However, the limited conversion of polysulfides in sulfur cathodes deteriorates the performance of Li‐S batteries. In this study, we develop a novel titanium nitride (TiN) catalyst for sulfur cathodes via atomic layer deposition (ALD). The synthesized ALD‐TiN catalyst shows controllable ultrafine particle size (<2 nm) and uniform distribution at the nanoscale in the carbon matrix. Combined with electrochemical analysis and multiple post‐characterization techniques, ALD‐TiN demonstrates an excellent catalytic effect to facilitate the nucleation and deposition of Li2S, which effectively suppresses the dissolution and shuttle of polysulfides. The as‐prepared sulfur cathodes, with the assistance of TiN catalyst, exhibit excellent cycling performance at a high rate (4 C) and deliver 200% higher discharge capacity than the pristine Sulfur‐pristine porous carbon composite cathodes. [ABSTRACT FROM AUTHOR]

Catalytic materials are effective in promoting sulfur utilization in lithium‐sulfur batteries. Co phthalocyanine (CoPc) presents a unique planner single‐molecular structure with a highly active Co‐N4 center for sulfur reduction catalysis. The high flexibility of phthalocyanines offers rich opportunities for electronic structure modulation toward enhanced catalytic activities. To guide future design and screening, this study aims to understand the impact of peripheral substitution, the most common method to obtain CoPc derivatives, by examining two typical substituents: the electron‐withdrawing nitro and electron‐donating amino groups. Co tetranitrophthalocyanine (CoTnPc) presents a significantly higher activity in promoting the liquid‐solid transition process than Co tetraaminophthalocyanine (CoTaPc). Substitution alters the stable binding geometry of Li2S4 by influencing the electrostatic potential and Li─bond, making the Co─S bond energetically favorable with the bridging S atoms on CoTnPc. CoTnPc also enables a greater electron donation from the S 3pz orbital to the singly occupied Co 3dz2${d}_{{z}^2}$ orbital, significantly weakening the bridging S─S bond to enhance the reactivity of Li2S4 for the subsequent liquid‐solid transition. A framework of theoretical calculation is tested, providing descriptors for the screening of related materials. The potential of CoPc derivatives is demonstrated by pouch cells with CoTnPc under high sulfur loading and limited electrolyte addition. [ABSTRACT FROM AUTHOR]

To overcome the shuttle effect and improve the energy density of Li–S batteries, developing free‐standing sulfur carriers with high capture and catalytic effect towards polysulfides is an effective strategy. Herein, a MXene/reduced graphene oxide/C3N4 aerogel (MG/C3N4) with three‐dimensional architecture prepared through low‐temperature hydrothermal approach followed by thermal treatment is used as sulfur carrier for free‐standing cathode of Li‐S batteries. In the MG/C3N4, MXene and rGO construct a highly conductive framework, and the MXene nanosheets offer chemical capture and catalytic activity towards lithium polysulfides, in favor of good cycling stability. The introduction of g‐C3N4 further enhances the reactivity of C‐Ti‐N at the hetero‐interface by engineering the electronic state of Ti atoms, leading to the optimized metal d‐band for expediting the multistep conversion of sulfur electrochemistry. Therefore, the free‐standing sulfur cathode with MG/C3N4 carrier achieves excellent performance with a capacity of 1315.6 mAh g−1 at 0.2 C and a capacity retention of 97.5% after 100 cycles as well as superior rate capability with 1167.4 mAh g−1 at 2 C. Even at a high sulfur loading of 4.92 mg cm−2, the cathode remains 940.3 mAh g−1 (4.62 mAh cm−2) after 200 cycles, indicating its promising potential for achieving high‐performance Li‐S batteries. [ABSTRACT FROM AUTHOR]

This review presents a comprehensive overview of the special strategies employed to boost the electrochemical performances of TMBs in Li-S batteries. [Display omitted] Although the lithium-sulfur (Li-S) battery has a theoretical capacity of up to 1675 mA h g−1, its practical application is limited owing to some problems, such as the shuttle effect of soluble lithium polysulfides (LiPSs) and the growth of Li dendrites. It has been verified that some transition metal compounds exhibit strong polarity, good chemical adsorption and high electrocatalytic activities, which are beneficial for the rapid conversion of intermediate product in order to effectively inhibit the "shuttle effect". Remarkably, being different from other metal compounds, it is a significant characteristic that both metal and boron atoms of transition metal borides (TMBs) can bind to LiPSs, which have shown great potential in recent years. Here, for the first time, almost all existing studies on TMBs employed in Li-S cells are comprehensively summarized. We firstly clarify special structures and electronic features of metal borides to show their great potential, and then existing strategies to improve the electrochemical properties of TMBs are summarized and discussed in the focus sections, such as carbon-matrix construction, morphology control, heteroatomic doping, heterostructure formation, phase engineering, preparation techniques. Finally, the remaining challenges and perspectives are proposed to point out a direction for realizing high-energy and long-life Li-S batteries. [ABSTRACT FROM AUTHOR]