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Lithium‐sulfur batteries (LSBs) are known as high energy density, but their performance deteriorates sharply under high/low‐temperature surroundings, due to the sluggish kinetics of sulfur redox conversion and Li+ transport. Herein, a catalytic strategy of phase reconstruction with abundant "electron‐Li+" reservoirs has been proposed to simultaneously regulate electron and Li+ exchange. As a demo, the 1T‐phase lithiation molybdenum disulfide grown on hollow carbon nitride (1T‐LixMoS2/HC3N4) is achieved via in situ electrochemical modulation, where the 1T‐LixMoS2 serves as an auxiliary "Li+ source" for facilitating Li+ transport and the HC3N4 acts as an electron donor for electronic supplier. From the theoretical calculations, experimental and post‐modern analyses, the relationship between the catalytic behaviors and mechanism of "electron‐Li+" reservoirs in accelerating the rate‐determining kinetics of sulfur species are deeply understood. Consequently, the cells with 1T‐LixMoS2/HC3N4/PP functional separator demonstrate excellent long‐term electrochemical performance and stabilize the areal capacity of 6 mAh cm−2 under 5.0 mg cm−2. Even exposed to robust surroundings from high (60 °C) to low (0 °C) temperatures, the optimized cells exhibit high‐capacity retention of 76.2% and 90.4% after 100 cycles, respectively, pointing out the potential application of catalysts with phase reconstruction‐assisted "electron‐Li+" reservoirs in LSBs. [ABSTRACT FROM AUTHOR]

Aqueous zinc batteries based on the conversion‐type sulfur cathodes are promising in energy storage system due to the high theoretical energy density, low cost, and good safety. However, the multi‐electron solid‐state intermediate conversion reaction of sulfur cathodes generally possess sluggish kinetics, which leads to lower discharge voltage and inefficient sulfur utilization, thus suppressing the practical energy density. Herein, sulfur nanoparticles derived from metal–organic frameworks confined in situ within electrospun fibers derived sulfur and nitrogen co‐doped carbon nanofibers (S@S,N−CNF) composite, which possesses yolk–shell S@C nanostructure, is fabricated through successive sulfidation, pyrolysis, and sulfide oxidation processes, and served as a high‐performance cathode material for Zn−S battery. The S and N dopants on carbon can collectively catalyse sulfur reduction reaction (SRR) by lowering energy barrier and accelerating kinetics to increase discharge voltage and specific capacity. Meanwhile, the yolk–shell S@C structure with spatially confined S nanoparticle yolks is beneficial to improve charge transfer and lower activation energy, thus further expediting SRR kinetics. Furthermore, extensive density functional theory (DFT) calculations reveal that S and N dual‐doping can thermodynamically and dynamically reduce the energy barrier of rate‐determining step (i.e., the transformation of *ZnS4 into *ZnS2) for the overall SRR, thereby significantly accelerating SRR kinetics. [ABSTRACT FROM AUTHOR]

The electrocatalytic sulfur reduction reaction (SRR) would allow the production of renewable high‐capacity rechargeable lithium‐sulfur (Li‐S) batteries using sustainable and nontoxic elemental sulfur as a cathode material, but its slow reaction rate causes a serious shuttle effect and dramatically reduces the capacity. We found that a catalyst composed of Pd nanoparticles supported by ordered mesoporous carbon (Pd/OMC) had a high reaction rate in the SRR, and a Li‐S battery assembled with this catalyst had a low shuttle constant of 0.031 h−1 and a high‐rate performance with a specific capacity of 1527 mAh g−1 at 0.1 C which is close to the theoretical value. The high activity of Pd/OMC with a d‐orbital vacancy of 0.87 e was predicted from a volcano relationship between the d charge for the metal and the adsorption activation entropy and reaction rate for the SRR by examining Pd, Au, Pt, Rh, and Ru transition‐metal nanocatalysts. The strategy of using a single electronic structure descriptor to design high‐efficiency SRR catalysts has suggested a way to produce practical Li‐S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • ITS coating was synthesized by magnetron sputtering method. • ITS coating promotes the conversion of intermediate and avoids the shuttle effect. • Modulated band structure of ITS enables fast interfacial charge transfer capability. • ITS/S/C cathode displays high reversible capacity and good cycling performance. Room-temperature sodium-sulfur (RT Na-S) batteries have been attracting enormous interests due to their low-cost, high capacity and environmental benignity. However, the shuttle effect and the sluggish electrochemical reaction activity of sodium polysulfides (NaPSs) seriously restrict their practical application. To solve these issues, we rationally designed an advanced Sn-doped In 2 S 3 /S/C cathode for RT Na-S batteries by magnetron sputtering in this work, which exhibited a high reversible capacity (1663.5 mAh g−1 at 0.1 A g−1) and excellent cycling performance (902.9 mAh g−1 after 50 cycles). The in situ electrochemical impedance spectroscopy indicated that the Sn-doped In 2 S 3 coating can accelerate charge-transfer kinetics and facilitate the diffusion of Na+. Furthermore, theoretical calculation revealed that doping of Sn into In 2 S 3 can reduce the energy band gap, thus accelerating the electron transfer and promoting the electrochemical conversion of active species. It is demonstrated that adjusting the electronic structure is a reliable method to improve the electrocatalytic effect of catalyst and significantly improve the performance of S cathode in RT Na-S batteries. [ABSTRACT FROM AUTHOR]

Defects and morphology engineering is a serviceable strategy to boost the electrochemical energy conversion and storage performance of carbon-based materials. In this study, nitrogen/sulfur codoped carbon nanotubes (NS-CNTs) were first obtained via the pyrolysis of presynthesized polyaniline nanotubes with micelles composed of methyl orange and ferric chloride acting as the soft template. Furthermore, intrinsic carbon defects and mesopores were introduced to obtain etched NS-CNTs (ENS-CNTs) composites by ammonia etching. The rational combination of intrinsic/extrinsic defects and porous nanotube morphology features is beneficial to the oxygen reduction reaction (ORR) and sulfur reduction reaction (SRR) performances of the ENS-CNTs electrode. The coexistence of intrinsic carbon defects and extrinsic N/S dopants can create massive catalytically active sites for electrochemical processes, while the porous one-dimensional nanotube-like carbon framework is responsible for accessibility of catalytic active sites, species hosting, electrical conductivity, mass transport, and stability. Consequently, the ENS-CNTs-30 (where 30 represents the corresponding etching time in minutes) electrode for ORR displayed a high half-wave potential of 859 mV vs RHE, a diffusion limiting current density of 6.65 mA cm–2, admirable stability, and methanol tolerance. The solid Zn–air battery (ZAB) assembled with ENS-CNTs-30 as the active material for the air cathode revealed remarkable power density (137 mW cm–2) and specific capacity (1467.4 mAh g–1Zn). Meanwhile, the ENS-CNTs-30 electrode for SRR also demonstrated ameliorative lithium–polysulfide (LiPS) trapping capability and Li2S deposition kinetics. The lithium–sulfur battery (LSB) with ENS-CNTs-30 as sulfur host material unfolded initial capacities of 1100 and 883 mAh g–1 at 0.2 and 2 C, respectively, and a capacity retention ratio of 82.0% after 200 cycles at 0.2 C. This work provides a feasible strategy for defects and morphology engineering of multifunctional carbon-based catalysts in electrochemical energy conversion and storage fields. [ABSTRACT FROM AUTHOR]

Toward practical lithium−sulfur (Li−S) batteries, there is a pressing need to improve the rate performance and longevity of cells. Herein, we report developing a cathode electrocatalyst Lu SA/NC, capable of accelerating sulfur redox kinetics with a high specific capacity of 1391.8 mAh g−1 at 0.1 C, and a low-capacity fading rate of 0.049 % per cycle over 1000 cycles even with a high sulfur loading (5.96 mg cm−2). The unparalleled cathodes are built upon the unique structure in which single-atoms of rare earth metals are doped in nitrogen-doped porous carbon (RM SAs/NC). The theoretical and experimental studies reveal that the rare earth Lu atom has an unrivaled adsorption capacity for polysulfides and can promote facile deposition and dissolution reactions in charge-discharge processes. The in-situ Raman experiments provide direct evidence for its promotion of polysulfide transformation to eliminate the shuttle effect. The theoretical calculations suggest that the presence of f-d-p hybridization enables accelerating sulfur reduction kinetics and enhancing lithium−sulfur battery performance. The strategic paradigm introduced in this study underscores significant practical potential in the exploration of rare earth single-atom catalysts for high performance Li−S batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

Appling an electrochemical catalyst is an efficient strategy for inhibiting the shuttle effect and enhancing the S utilization of Li‐S batteries. Carbon‐based materials are the most common conductive agents and catalyst supports used in Li‐S batteries, but the correlation between the diversity of hybridizations and sulfur reduction reaction (SRR) catalytic activity remains unclear. Here, by establishing two forms of carbon models, i.e. graphitic carbon (GC) and amorphous carbon (AC), we observe that the nitrogen atom doped in the GC possesses a higher local charge density and a lower Gibbs free energy towards the formation of polysulfides than in the AC. And the GC‐based electrode consistently inherits considerably enhanced SRR kinetics and superior cycling stability and rate capability in Li‐S batteries. Therefore, the function of carbon in Li‐S batteries is not only limited as conductive support but also plays an unignorable contribution to the electrocatalytic activities of SRR. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) battery is strongly considered as one of the most promising energy storage systems due to its high theoretical energy density and low cost. However, the sluggish reduction kinetics from Li2S4 to Li2S during discharge hinders the practical application of Li–S batteries. Although various electrocatalysts have been proposed to improve the reaction kinetics, the electrocatalytic mechanism is unclear due to the complexity of sulfur reduction reactions (SRR). It is crucial to understand the electrocatalytic mechanism thoroughly for designing advanced electrocatalysts. Herein an electrocatalytic model is constructed to reveal the chemical mechanism of the SRR in Li–S batteries based on systematical density functional theory calculations, taking heteroatoms‐doped carbon materials as an example. The adsorption energy of LiSy⋅ (y=1, 2, or 3) radicals is used as a key descriptor to predict the reaction pathway, rate‐determining step, and overpotential. A diagram for designing advanced electrocatalysts is accordingly constructed. This work establishes a theoretical model, which is an intelligent integration for probing the complicated SRR mechanisms and designing advanced electrocatalysts for high‐performance Li–S batteries. [ABSTRACT FROM AUTHOR]

Efficient catalyst design is important for lean‐electrolyte sulfur reduction in Li−S batteries. However, most of the reported catalysts were focused on catalyst‐polysulfide interactions, and generally exhibit high activity only with a large excess of electrolyte. Herein, we proposed a general rule to boost lean‐electrolyte sulfur reduction by controlling the catalyst‐solvent interactions. As evidenced by synchrotron‐based analysis, in situ spectroscopy and theoretical computations, strong catalyst‐solvent interaction greatly enhances the lean‐electrolyte catalytic activity and battery stability. Benefitting from the strong interaction between solvent and cobalt catalyst, the Li−S battery achieves stable cycling with only 0.22 % capacity decay per cycle with a low electrolyte/sulfur mass ratio of 4.2. The lean‐electrolyte battery delivers 79 % capacity retention compared with the battery with flooded electrolyte, which is the highest among the reported lean‐electrolyte Li−S batteries. [ABSTRACT FROM AUTHOR]

Lithium–sulfur batteries are one of the most promising alternatives for advanced battery systems due to the merits of extraordinary theoretical specific energy density, abundant resources, environmental friendliness, and high safety. However, the sluggish sulfur reduction reaction (SRR) kinetics results in poor sulfur utilization, which seriously hampers the electrochemical performance of Li–S batteries. It is critical to reveal the underlying reaction mechanisms and accelerate the SRR kinetics. Herein, the critical issues of SRR in Li–S batteries are reviewed. The conversion mechanisms and reaction pathways of sulfur reduction are initially introduced to give an overview of the SRR. Subsequently, recent advances in catalyst materials that can accelerate the SRR kinetics are summarized in detail, including carbon, metal compounds, metals, and single atoms. Besides, various characterization approaches for SRR are discussed, which can be divided into three categories: electrochemical measurements, spectroscopic techniques, and theoretical calculations. Finally, the conclusion and outlook part gives a summary and proposes several key points for future investigations on the mechanisms of the SRR and catalyst activities. This review can provide cutting‐edge insights into the SRR in Li–S batteries. [ABSTRACT FROM AUTHOR]

Sluggish sulfur reduction reaction (SRR) kinetics remains a formidable challenge in Li–S electrochemistry. In this sense, the rational design of single‐atom species has become a burgeoning practice to expedite sulfur redox, where the underlying catalytic mechanism otherwise remains elusive. Herein, a class of metal single‐atom modified porous carbon nanofiber films (MSA PCNFs, M = Fe, Co, or Ni), fabricated via a generic synthetic strategy, as mediators to boost SRR kinetics is reported. Throughout electrokinetic measurement and operando instrumental probing, NiSA PCNF is evidenced to harness the catalytic superiority toward the rate‐determining step (i.e., liquid–solid conversion) of the SRR process. Density functional theory (DFT) simulations further reveal that the catalytic features of M–N–C moieties in catalyzing the Li2S precipitation rely heavily upon the coordination environments of adjacent carbon atoms and d‐orbital configurations of metal centers. In response, the thus‐derived S/NiSA PCNF cathode realizes an encouraging areal capacity of 14.12 mAh cm−2 under elevated sulfur loading (10.2 mg cm−2) and lean electrolyte usage (E/S ratio ≈ 5.5 μL mg−1). This work offers insight into the identification of exact catalytic moieties for different transition metal M–N–C single‐atom SRR mediators, showcasing a meaningful guidance and potential impact on Li–S catalysis. [ABSTRACT FROM AUTHOR]

Lithium‐sulfur battery is a promising candidate for next‐generation high energy density batteries due to its ultrahigh theoretical energy density. However, it suffers from low sulfur utilization, fast capacity decay, and the notorious "shuttle effect" of lithium polysulfides (LiPSs) due to the sluggish reaction kinetics, which severely restrict its practical applications. Using the electrocatalyst can accelerate the redox reactions between sulfur, LiPSs and Li2S and suppress the shuttling of LiPSs, and thus, it is a promising strategy to solve the above problems, enabling the battery with high energy density and long cycling stability. In this personal account, we discuss the catalyst design for lithium‐sulfur batteries according to the sulfur reduction reaction (SRR) and sulfur evolution reaction (SER) in the discharging and charging processes. The catalytic effects for each step in SRR and SER are highlighted and the homogenous catalysts, the selective catalysts, and the bidirectional catalysts are discussed, which can help guide the rational design of the catalysts and practical applications of lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li–S) batteries, with their high theoretical specific capacity and energy density, are considered a promising alternative to current energy storage technologies. However, their practical application is hindered by the polysulfide shuttle effect, which leads to capacity fade and reduced coulombic efficiency. In this study we employs density functional theory (DFT) to explore the use of two-dimensional (2D) metallic transition metal dichalcogenides (TMDs), tantalum diselenide (TaSe 2) and tantalum ditelluride (TaTe 2), as anchoring materials for lithium polysulfides (LiPSs). Our findings reveal that these TMD monolayers exhibit a balanced binding affinity towards LiPSs, ranging from 1.20ev to 3.34eV (TaSe 2) and from 2.35ev to 3.74eV (TaTe 2). Notably, the decomposition barriers for Li 2 S on TaSe 2 and TaTe 2 are significantly lower than those of bulk Li 2 S with a value of 1.62eV and 1.54eV, suggesting these materials can facilitate rapid charge-discharge processes. The introduction of strain, simulating the expansion during lithiation, demonstrates that these monolayers maintain their adsorption capabilities, a crucial attribute for practical applications, with a increased decomposition barriers of 2.4eV(TaSe 2) and 2.51eV(TaTe 2). The catalytic activity of these monolayers for the sulfur reduction reaction (SRR) was evaluated, showing a spontaneous conversion mechanism for lithium-sulfur clusters, which is expected to enhance the overall performance of Li–S batteries. This study presents TaSe 2 and TaTe 2 as innovative and promising candidates for advanced Li–S battery applications, offering a perspective in addressing the critical challenges associated with the polysulfide shuttle effect. Upper-left. Crystal orbital Hamilton population (COHP) of Li 2 S and S 8 adsorbed on TaSe 2 monolayer. The Fermi level is at zero. Upper-right. Decomposition pathway and its corresponding energy barriers for Li 2 S on TaSe 2 monolayer. Lower-left. Gibbs free energy distribution of sulfur reduction reaction on TaS 2 and TaTe 2 monolayer. Lower-right. Dissociation pathways and corresponding energy barriers of Li 2 S on the TaSe 2 subjected to strain (+10 %). [Display omitted] • Utilizes DFT to demonstrate that TaSe2 and TaTe2 monolayers effectively mitigate the polysulfide shuttle effect in Li–S batteries. • Employs COHP and CINEB methods to elucidate the bonding characteristics and decomposition barriers of Li2S clusters on TMDs. • Reveals that even under strain, TaSe2 and TaTe2 maintain their potential as superior adsorption materials for advanced Li–S battery applications. [ABSTRACT FROM AUTHOR]