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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]

Efficient catalysis of intermediate lithium polysulfide (LiPS) conversion in lithium-sulfur batteries is crucial for enhancing sulfur reduction reaction (SRR) kinetics and suppressing the shuttle effect of LiPSs. High-entropy alloys (HEAs), with their compositional flexibility, structural diversity, and multielement synergy, are promising high-efficiency catalyst candidates. Herein, a work function-dominated d-band center rule is proposed to modulate the chemical absorption ability of LiPSs and the catalytic performance of HEA catalysts. The d-band center of the as-screened PtCuFeCoNi HEAs (PCFCN-HEAs) is modulated via distinct work functions of its five metallic elements. In addition, detailed density functional theory (DFT) calculations and X-ray absorption spectroscopy are performed to reveal the roles of individual metallic elements in HEAs. Optimizing the d-band center of PCFCN-HEAs notably enhances the adsorption of LiPSs and accelerates the SRR. PCFCN-HEA nanoparticles are deposited on the surface of hollow carbon spheres (HCSs) and they combine with hyphae carbon nanobelts (HCNBs) to form a PCFCN-HEA/HCS/HCNB composite as the sulfur host. The cathode with PCNFC-HEA catalyst exhibits stable cycling at 6C and delivers a high reversible capacity of 652 mAh g -1 even at a high rate of 8C. DFT calculations further elucidate the stepwise catalytic mechanism of PCFCN-HEAs, offering a pathway for designing high-efficiency catalysts.

The major challenges in enhancing the cycle life of lithium-sulfur (Li-S) batteries are polysulfide (PS) shuttling and sluggish reaction kinetics (S to Li 2 S, Li 2 S to S). To alleviate the above issues, the use of heteroatom-doped carbon as a cathode host matrix is a low-cost and efficient approach, as it works as a dual-functional framework for PS anchoring as well as an electrocatalyst for faster redox kinetics. Here, the dual role of heteroatom-doped carbon sheets (CS) in the chemisorption of Li 2 S 6 and catalysis of its faster conversion to Li 2 S is established. To substantiate the catalytic effect, composite cathodes were prepared by encapsulating sulfur in CS which is further blended with carbon nanotubes (CNTs) to form a free-standing cathode. The electrochemical performances of the three cathodes (S@Fe-N-CS-CNT, S@Fe-S-CS-CNT, and S@Fe-NS-CS-CNT) were evaluated by constructing Li-S cells. The S@Fe-NS-CS-CNT delivers a high initial discharge capacity of 1017 mAh g -1 at 0.5 C rate and sustains a capacity of 751 mAh g -1 after 260 cycles with a capacity retention of 73.8 %. Even at a high S loading (12 mg cm -2 ), it delivers an initial discharge capacity of 892 mAh g -1 and retained 575 mAh g -1 after 200 cycles., (© 2024 Wiley-VCH GmbH.)

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]

The adsorption-conversion paradigm of polysulfides during the sulfur reduction reaction (SRR) is appealing to tackle the shuttle effect in Li-S batteries, especially based upon atomically dispersed electrocatalysts. However, mechanistic insights into such catalytic systems remain ambiguous, limiting the understanding of sulfur electrochemistry and retarding the rational design of available catalysts. Herein, we systematically explore the polysulfide adsorption-conversion essence via a geminal-atom model system to understand the catalyst roles toward an expedited SRR. A descriptor involving an electronic structure index ( I ES ) and electron affinity index ( I EA ) is proposed, considering the geometric and electronic dictation within a Fe/M (M: 3d-block transition metal) atomic ensemble. With the aid of theoretical computation, we managed to identify the SRR thermodynamic/kinetic trends of Fe/M moieties. Guided by these findings, we in target design a Fe/V-NC dual-atom catalyst, which harvests a minimum I ES and maximum I EA , accordingly demonstrating enhanced polysulfide adsorption-conversion and improved full-cell performances. Such a consistency between a computational descriptor and experimental evidence highlights the importance of an atomic catalyst screen and selection for Li-S batteries.

Electrocatalytic sulfur reduction reaction (SRR) is emerging as an effective strategy to combat the polysulfide shuttling effect, which remains a critical factor impeding the practical application of the Li-S battery. Single-atom catalyst (SAC), one of the most studied catalytic materials, has shown considerable potential in addressing the polysulfide shuttling effect in a Li-S battery. However, the role played by transition metal vs coordination mode in electrocatalytic SRR is trial-and-error, and the general understanding that guides the synthesis of the specific SAC with desired property remains elusive. Herein, we use first-principles calculations and machine learning to screen a comprehensive data set of graphene-based SACs with different transition metals, heteroatom doping, and coordination modes. The results reveal that the type of transition metal plays the decisive role in SAC for electrocatalytic SRR, rather than the coordination mode. Specifically, the 3d transition metals exhibit admirable electrocatalytic SRR activity for all of the coordination modes. Compared with the reported N 3 C 1 and N 4 coordinated graphene-based SACs covering 3d, 4d, and 5d transition metals, the proposed para-MnO 2 C 2 and para-FeN 2 C 2 possess significant advantages on the electrocatalytic SRR, including a considerably low overpotential down to 1 mV and reduced Li 2 S decomposition energy barrier, both suggesting an accelerated conversion process among the polysulfides. This study may clarify some understanding of the role played by transition metal vs coordination mode for SAC materials with specific structure and desired catalytic properties toward electrocatalytic SRR and beyond.

The sluggish sulfur reduction reaction (SRR) kinetics of lithium-sulfur (Li-S) batteries seriously limits the development of Li-S batteries. The initial reduction of solid (S 8 ) to liquid (soluble Li 2 S n (4≤n≤8)) is relatively easy due to the low activation energy, whereas the subsequent conversion of liquid (soluble Li 2 S n ) to solid (insoluble Li 2 S 2 /Li 2 S) has much higher activation energy, which leads to the accumulation of Li 2 S n and exacerbates the shuttle effect of Li 2 S n . Therefore, establishing one selective catalyst that decelerates the previous solid-liquid reaction and accelerates the subsequent liquid-solid reaction is essential for rational tailoring of the SRR for improved performance of Li-S batteries, but it represents a daunting challenge. Here, considering that the indium oxide catalyst possesses selective catalytic properties and drawing inspiration from the theoretical calculations, In 2 O 3 nanospheres containing phosphorus doping and oxygen vacancies (P-O V -In 2 O 3 NSs) are designed and synthesized as a selective catalyst for Li-S batteries. Contributed by the unique selective catalytic capability, the batteries using P-O V -In 2 O 3 NSs modified separators exhibit excellent sulfur utilization, superb rate performance (656 mAh g -1 at 5.0 C), and low-capacity decay rate of about 0.069% per cycle over 500 cycles at 1.0 C., (© 2024 Wiley‐VCH GmbH.)

The commercial viability of emerging lithium-sulfur batteries (LSBs) remains greatly hindered by short lifespans caused by electrically insulating sulfur, lithium polysulfides (Li 2 S n ; 1 ≤ n ≤ 8) shuttling, and sluggish sulfur reduction reactions (SRRs). This work proposes the utilization of a hybrid composed of sulfiphilic MoS 2 and mayenite electride (C12A7:e - ) as a cathode host to address these challenges. Specifically, abundant cement-based C12A7:e - is the most stable inorganic electride, possessing the ultimate electrical conductivity and low work function. Through density functional theory simulations, the key aspects of the MoS 2 /C12A7:e - hybrid including electronic properties, interfacial binding with Li 2 S n , Li + diffusion, and SRR have been unraveled. Our findings reveal the rational rules for MoS 2 as an efficient cathode host by enhancing its mutual electrical conductivity and surface polarity via MoS 2 /C12A7:e - . The improved electrical conductivity of MoS 2 is attributed to the electron donation from C12A7:e - to MoS 2 , yielding a semiconductor-to-metal transition. The resultant band positions of MoS 2 /C12A7:e - are well matched with those of conventional current-collecting materials ( i.e ., Cu and Ni), electrochemically enhancing the electronic transport. The accepted charge also intensifies MoS 2 surface polarity for attracting polar Li 2 S n by forming stronger bonds with Li 2 S n via ionic Li-S bonds than electrolytes with Li 2 S n , thereby preventing polysulfide shuttling. Importantly, MoS 2 /C12A7:e - not only promotes rapid reaction kinetics by reducing ionic diffusion barriers but also lowers the Gibbs free energies of the SRR for effective S 8 -to-Li 2 S conversion. Beyond the reported applications of C12A7:e - , this work highlights its functionality as an electrode material to boost the efficiency of LSBs.

Slow electrochemistry kinetics and dendrite growth are major obstacles for lithium-sulfur (Li-S) batteries. The investigations over the polymorph effect require more endeavors to further access the related catalyst design principles. Herein, the systematic evaluation of CoTe 2 alloy with two polymorphs regarding sulfur reduction reaction (SRR) and lithium plating/stripping is reported. As disclosed by theoretical calculations and electrochemical measurements, the orthorhombic (o-) and hexagonal (h-) CoTe 2 make a substantial difference. The reactivity origin of the CoTe 2 polymorphs is explored. The higher position of d-band centers for the Co atoms on the o-CoTe 2 leads to a higher displacement of the antibonding state; the lower antibonding state occupancy, the more effective the interaction with the sulfide moieties and lithium. Hence, o-CoTe 2 annihilates h-CoTe 2 and exhibits better catalysis and more uniform lithium deposition, consolidated by excellent performance of full cell made of o-CoTe 2 . It keeps stable charging/discharging for 800 cycles at 0.5 C with only 0.055% capacity decay per cycle and even achieves an areal capacity of 6.5 mAh cm -2 at lean electrolyte and high sulfur loading of 6.4 mg cm -2 . This work establishes the mechanistic perspective about the catalysts in Li-S batteries and provides new insight into the unified solution., (© 2023 Wiley-VCH GmbH.)

Transition metal dichalcogenides (TMDs) have been widely studied as catalysts for lithium-sulfur batteries due to their good catalytic properties. However, their poor electronic conductivity leads to slow sulfur reduction reactions. Herein, a simple Zn 2+ intercalation strategy was proposed to promote the phase transition from semiconducting 2H-phase to metallic 1T-phase of MoS 2 . Furthermore, the Zn 2+ between layers can expand the interlayer spacing of MoS 2 and serve as a charge transfer bridge to promote longitudinal transport along the c -axis of electrons. DFT calculations further prove that Zn-MoS 2 possesses better charge transfer ability and stronger adsorption capacity. At the same time, Zn-MoS 2 exhibits excellent redox electrocatalytic performance for the conversion and decomposition of polysulfides. As expected, the lithium-sulfur battery using Zn 0.12 MoS 2 -carbon nanofibers (CNFs) as the cathode has high specific capacity (1325 mAh g -1 at 0.1 C), excellent rate performance (698 mAh g -1 at 3 C), and outstanding cycle performance (it remains 604 mAh g -1 after 700 cycles with a decay rate of 0.045% per cycle). This study provides valuable insights for improving electrocatalytic performance of lithium-sulfur batteries.

As an attractive high-energy-density technology, the practical application of lithium-sulfur (Li-S) batteries is severely limited by the notorious dissolution and shuttle effect of lithium polysulfides (LiPS), resulting in sluggish reaction kinetics and uncontrollable dendritic Li growth. Herein, a p-n typed heterostructure consisting of n-type MoS 2 nanoflowers embedded with p-type NiO nanoparticles is designed on carbon nanofibers (denoted as NiO-MoS 2 @CNFs) as both cathode sulfur immobilizer and anode Li stabilizer for practical Li-S batteries. Such p-n typed heterostructure is proposed to establish the built-in electric field across the heterointerface for facilitated the positive charge to reach the surface of NiO-MoS 2 , meanwhile inherits the excellent LiPS adsorption ability of p-type NiO nanoparticles and catalytic ability of n-type MoS 2 . As the anode matrix, the implementation of NiO-MoS 2 heterostructure can prevent the growth of Li dendrites by enhancing the lithiophilicity and reducing local current density. The obtained Li-S full battery exhibits an ultra-high areal capacity over 7.3 mAh cm -2 , far exceeding that of current commercial Li-ion batteries. Meanwhile, a stable cycling performance can be achieved under low electrolyte/sulfur ratio of 5.8 µL mg -1 and negative/positive capacity ratio of 1. The corresponding pouch cell maintains high energy density of 305 Wh kg -1 and stable cycling performance under various bending angles., (© 2023 Wiley-VCH GmbH.)

Currently, extensive research efforts are being devoted to suppressing the shuttle effect of polysulfides. The uncontrollable deposition of insulating Li 2 S onto the surface of sulfur host materials dramatically inhibits the continuous reduction of polysulfides in lithium-sulfur (Li-S) batteries. Herein, N,B co-doped hollow carbon microspheres embedded with dense FeSe-MnSe heterostructures and abundant Se vacancies (FeSe-MnSe/NBC) are rationally designed and synthesized via a facile hydrothermal reaction using ionic liquids as dopants. The introduction of abundant heterostructures subtly guides Li 2 S nucleation and deposition in 3D frameworks, thus avoiding the formation of the Li 2 S passivation layer and allowing for continuous Li + diffusion and subsequent nucleation of Li 2 S. Owing to these beneficial features, Li-S batteries comprising an FeSe-MnSe/NBC electrode exhibit significantly improved performance, including a high initial capacity of 1334 mAh g -1 at 0.2 C and ultralong cycle stability with a low capacity fading rate of 0.029% cycle -1 over 1000 cycles at 1.0 C. Remarkably, the FeSe-MnSe/NBC pouch cell delivers a considerable areal capacity of 3.6 mAh cm -2 at 0.1 C. This study provides valuable insight into heterostructures and Se vacancies for developing practical Li-S batteries., (© 2022 Wiley-VCH GmbH.)

Lithium-sulfur (Li-S) batteries are considered as one of the most promising next-generation rechargeable batteries owing to their high energy density and cost-effectiveness. However, the sluggish kinetics of the sulfur reduction reaction process, which is so far insufficiently explored, still impedes its practical application. Metal-organic frameworks (MOFs) are widely investigated as a sulfur immobilizer, but the interactions and catalytic activity of lithium polysulfides (LiPs) on metal nodes are weak due to the presence of organic ligands. Herein, a strategy to design quasi-MOF nanospheres, which contain a transition-state structure between the MOF and the metal oxide via controlled ligand exchange strategy, to serve as sulfur electrocatalyst, is presented. The quasi-MOF not only inherits the porous structure of the MOF, but also exposes abundant metal nodes to act as active sites, rendering strong LiPs absorbability. The reversible deligandation/ligandation of the quasi-MOF and its impact on the durability of the catalyst over the course of the electrochemical process is acknowledged, which confers a remarkable catalytic activity. Attributed to these structural advantages, the quasi-MOF delivers a decent discharge capacity and low capacity-fading rate over long-term cycling. This work not only offers insight into the rational design of quasi-MOF-based composites but also provides guidance for application in Li-S batteries., (© 2021 Wiley-VCH GmbH.)

Precisely tuning the coordination environment of the metal center and further maximizing the activity of transition metal-nitrogen carbon (M-NC) catalysts for high-performance lithium-sulfur batteries are greatly desired. Herein, we construct an Fe-NC material with uniform and stable Fe-N 2 coordination structure. The theoretical and experimental results indicate that the unsaturated Fe-N 2 center can act as a multifunctional site for anchoring lithium polysulfides (LiPSs), accelerating the redox conversion of LiPSs and reducing the reaction energy barrier of Li 2 S decomposition. Consequently, the batteries based on a porous carbon nitride supported Fe-N 2 site (Fe-N 2 /CN) host exhibit excellent cycling performance with a capacity decay of 0.011% per cycle at 2 C after 2000 cycles. This work deepens the understanding of the relationship between electronic structure of M-NC sites and the catalysis effect for the conversion of LiPSs. This strategy also provides a potent guidance for the further application of M-NC materials in advanced lithium-sulfur batteries.