Cycling Stability Of Lithium-sulfur Batteries Research Articles

Tailoring iron hexadecafluorophthalocyanine/GO nanocomposite separators for polysulfide adsorption and enabling fast electrochemical kinetics of Li-S batteries

The cycling stability of lithium-sulfur batteries is significantly compromised by the shuttle effect. Herein, we employed a preformed process to successfully load spherical nanoparticles of Iron hexadecafluorophthalocyanine (FePcF16) with sizes between 10 and 20 nm onto oxidized graphene sheets. The FePcF16 spherical particles with lithium and sulfur-affinitive sites maximally expose catalytically active sites, facilitating effective adsorption and catalysis of polysulfides (LiPSs). Density-functional theory (DFT) calculations suggest that the electron-rich fluorine substituents enhance the conjugation effect of FePcF16, facilitating electronic communication between the catalyst and graphene oxide (GO), achieving precise modulation of the electronic structure of Fe-N4 active centers. The electrochemical analysis demonstrates that the nanostructured and Fe-N4 site-containing FePcF16 integrated with the robust two-dimensional graphene structure synergistically facilitates both redox reactions and lithium affinity effects. Consequently, in extended cycling tests at 2 C, the initial discharge-specific capacity reached 857.7 mAh g−1. After 500 cycles, the capacity remained at 737.7 mAh g−1, with a minimal capacity decay rate of only 0.028 % per cycle.

Anchoring effect of transition metal dihaloalkanes in lithium-sulfur batteries: A first-principles study

Suppressing the shuttle effect by enhancing the sulfur electrode structure is an effective method to achieve long-term cycle stability of lithium-sulfur batteries. In which, two-dimensional materials are widely used to improve the performance of lithium-sulfur batteries because of their high specific surface area and high electrical conductivity. In this paper, the anchoring effect of NbX2 (X= S,Se,Te) on polysulfides, and the conductivity, stability and diffusion behavior of the adsorption system are studied by using density functional theory calculation. The results show that NbX2 (X= S,Se,Te) has good electrical conductivity and stability, where NbS2 has moderate adsorption strength (0.84–3.28 eV) for lithium polysulfides, and the interaction of S atoms on the surface of Li2S and Nb atoms on the substrate surface is the main source of adsorption energy. In addition, the diffusion potential barrier is low (0.12 eV). The calculated results show that NbS2 may be a potential choice as an anchoring material for Li-sulfur batteries.

Unveiling the Reaction Mystery Between Lithium Polysulfides and Lithium Metal Anode in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are widely regarded as one of the most promising next-generation high-energy-density energy storage devices. However, soluble lithium polysulfides (LiPSs) corrode Li metal and deteriorate the cycling stability of Li-S batteries. Understanding the reaction mechanism between LiPSs and Li metal anode is imperative. Herein, the reaction rate and products of LiPSs with Li metal anode, the composition and structure of the as-generated solid electrolyte interphase (SEI), and the mechanism of lithium nitrate (LiNO3) additives for inhibiting the corrosion reactions are systematically unveiled. Concretely, LiPSs react with Li metal anode more rapidly than Li salt and generate a Li2S-rich SEI. The Li2S-rich SEI is highly reactive with LiPSs, which exacerbates the formation of dendritic Li and the continuous corrosion of active Li. LiNO3 functions dominantly by modulating the solvation structure of LiPSs and inherently reducing the reactivity of LiPSs, rather than the conventional understanding of LiNO3 participating in the formation of SEI. This work reveals the reaction mechanism between LiPSs and Li metal anode and inspires rational regulating of the solvation structure of LiPSs for stabilizing Li metal anode in Li-S batteries.

The Impact of Biomass-Derived Graphene-like Porous Carbon Decorated with NiO Nanoparticles on the Electrochemical Performance of Lithium-Sulfur Batteries

Lithium-sulfur batteries are considered a promising next-generation energy storage system, boasting high theoretical capacity and energy density, approximately double that of LiBs [1,2]. However, challenges such as low sulfur conductivity, significant volume expansion during cycling, and the lithium polysulfides shuttle effect hinder their practical use [3]. These issues result in side reactions, irreversible loss of active material, and anode degradation, leading to a rapid decline in cell capacity stability [4].In this research, we successfully developed a sulfur cathode carbon matrix and separator modifier from rice husk through carbonization and thermal activation. The resulting graphene-like porous carbon (GPC) exhibited high efficiency as a sulfur host, enhancing the electrochemical performance of the cathode. The GPC-NiO composite also served effectively as a separator modifier, catalyzing lithium polysulfides' redox reactions and improving the overall cycling stability of lithium-sulfur batteries. In particular, the GPC@S/GPC-NiO-20 cell demonstrated an excellent initial discharge capacity of 1519 mAh g-1 at 0.2 C. Also, it delivered excellent long-term cycling, maintaining a discharge capacity of 661 mAh g-1 even after 400 cycles at 1 C, with a Coulombic efficiency exceeding 97%. It exhibited a promising rate capability of 568 mAh g-1 at 2 C and retained a discharge capacity of 603 mAh g-1 over 100 cycles at 0.2 C with a sulfur loading of 4.0 mg cm-2. Acknowledgments This research is funded by the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan (Grant No. AP19677708).

High-Entropy Alloy Electrocatalysts Bidirectionally Promote Lithium Polysulfide Conversions for Long-Cycle-Life Lithium-Sulfur Batteries.

High-entropy alloys (HEAs) have attracted considerable attention, owing to their exceptional characteristics and high configurational entropy. Recent findings demonstrated that incorporating HEAs into sulfur cathodes can alleviate the shuttling effect of lithium polysulfides (LiPSs) and accelerate their redox reactions. Herein, we synthesized nano Pt0.25Cu0.25Fe0.15Co0.15Ni0.2 HEAs on hollow carbons (HCs; denoted as HEA/HC) by a facile pyrolysis strategy. The HEA/HC nanostructures were further integrated into hypha carbon nanobelts (HCNBs). The solid-solution phase formed by the uniform mixture of the five metal elements, i.e., Pt0.25Cu0.25Fe0.15Co0.15Ni0.2 HEAs, gave rise to a strong interaction between neighboring atoms in different metals, resulting in their adsorption energy transformation across a wide, multipeak, and nearly continuous spectrum. Meanwhile, the HEAs exhibited numerous active sites on their surface, which is beneficial to catalyzing the cascade conversion of LiPSs. Combining density functional theory (DFT) calculations with detailed experimental investigations, the prepared HEAs bidirectionally catalyze the cascade reactions of LiPSs and boost their conversion reaction rates. S/HEA@HC/HCNB cathodes achieved a low 0.034% decay rate for 2000 cycles at 1.0 C. Notably, the S/HEA@HC/HCNB cathode delivered a high initial areal capacity of 10.2 mAh cm-2 with a sulfur loading of 9 mg cm-2 at 0.1 C. The assembled pouch cell exhibited a capacity of 1077.9 mAh g-1 at the first discharge at 0.1 C. The capacity declined to 71.3% after 43 cycles at 0.1 C. In this work, we propose to utilize HEAs as catalysts not only to improve the cycling stability of lithium-sulfur batteries, but also to promote HEAs in energy storage applications.

Cellulose-based separator woven by double-layer-configuration fibers for high S-load Li-S batteries

Lithium-sulfur (Li-S) battery with high theoretical energy density, has been the most promising next-generation energy storage devices. However, the capacity of the high S-loaded cathode decays rapidly due to the shuttling of soluble polysulfide intermediates between the two electrodes, which seriously inhibits its development. In this work, polyacrylonitrile (PAN) and cellulose composite film (PAN@CE) is designed, which is woven by double-layer configuration fiber. The outer layer of fiber is mainly composed of cellulose, and the inner layer is mainly PAN. From DFT calculations and experiments, the double-layer configuration enriched with nitrogen and oxygen groups can effectively inhibit the shuttle of soluble polysulfides. Meanwhile, the interlaced network structure of PAN@CE improves the electrolyte wettability and provides abundance transport paths for ions. In addition, the film also has good thermal stability. Hence, the cycling stability of Li-S batteries with PAN@CE as separator has been greatly improved. Cellulose-based Li-S battery with 9.1 mg S loading and an E/S ratio of 6.2 μL mg−1 is assembled. Its initial area capacity is 5.67 mAh cm−2. After 200 long cycles, the area capacity keeps above 4.0 mAh cm−2.

In-situ synthesis Fe3C@C/rGO as matrix for high performance lithium-sulfur batteries at room and low temperatures

People have been focusing on how to improve the specific capacity and cycling stability of lithium-sulfur batteries at room temperature, however, on some special occasions such as cold cities and aerospace fields, the operating temperature is low, which dramatically hinders the performance of batteries. Here, we report an iron carbide (Fe3C)/rGO composite as electrode host, the Fe3C nanoparticles in the composite have strong adsorption and high catalytic ability for polysulfide. The rGO makes the distribution of Fe3C nanoparticles more disperse, and this specific structure makes the deposition of Li2S more uniform. Therefore, it realizes the rapid transformation and high performance of lithium-sulfur batteries at both room and low temperatures. At room temperature, after 100 cycles at 1C current density, the reversible specific capacity of the battery can be stabilized at 889 ± 7.1 mAh/g. Even at −40 °C, in the first cycle battery still emits 542.9 ± 3.7 mAh/g specific capacity. This broadens the operating temperature for lithium-sulfur batteries and also provides a new idea for the selection of host materials for sulfur in low-temperature lithium-sulfur batteries.

Binary transition metal sulfides MoS2–NiS2 anchored on biomass-derived carbon for improved performance of lithium–sulfur batteries

The poor electrical conductivity of sulfur and electrochemically active solid-state products (Li2Sn, n = 1–3), and the shuttle effect have led to the low cycling stability of lithium-sulfur batteries and the low utilization of the sulfur cathode. In this work, 3D porous biomass-derived carbon material (KMC) was prepared from Miscanthus sinensis by KOH activation. The transition metal sulfide with excellent adsorption and catalytic characteristics was effectively combined with the conductive porous biomass-derived carbon material, and a KMC/MoS2−NiS2 composite material was obtained. The product was characterized by field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Results show that MoS2−NiS2 nanoparticles can be uniformly distributed on the porous carbon material. Electrochemical measurements reveal that with an initial specific capacity of 1292 mA h g–1 at a current density of 0.1 C. After 400 cycles at 0.5 C, the specific capacity of KMC/MoS2−NiS2/S decays from 1007 to 814 mA h g–1. Thus, the capacity decay rate per cycle is about 0.054 %. This strategy provides a new idea for developing lithium−sulfur batteries with attractive performance.

Enhancing the cycling stability of Li-S batteries with flexible freestanding sulfur cathodes through a spider-hunting strategy

Flexible, high-capacity, and long-lasting freestanding sulfur cathodes are essential for developing advanced lithium-sulfur (Li-S) batteries in next-generation flexible electronic devices. However, the severe shuttle effect of lithium polysulfides (LiPSs) hinders their potential applications. This work introduces a flexible freestanding MX-CPNTs-CNTs@NS cathode for Li-S batteries by utilizing a spider-hunting strategy. In this strategy, carbonized polypyrrole nanotubes (CPNTs) and carbon nanotubes (CNTs) intertwine to form a 3D flexible and conductive spiderweb-like skeleton. The incorporation of MXene nanosheets as a function of spiders enables the regulation of a rich hierarchical porous structure. Additionally, the polar terminal functional groups of MXene nanosheets and the pyridinic N of CPNTs contribute to the chemical adsorption and electrocatalysis of LiPSs. The synergistic effect of physical and chemical inhibition strategies results in stable electrochemical performance, including a high specific capacity of 1203.2 mAh/g at 0.1C, and extended cycling stability of 739.6 mAh/g at 1C after 500 cycles (low decay rate of 0.036%). The excellent flexibility, specific capacity, and cycling stability make the freestanding MX-CPNTs-CNTs@NS cathode promising for high-performance flexible electronic devices.

Investigation of the corrosion behavior influence of carbon interlayer on aluminum collector in lithium-sulfur battery system

Due to the shuttle effect brought by polysulfides, the commercialization of lithium-sulfur batteries still faces significant difficulties. Carbon interlayer is introduced to enhance the electrochemical performance of lithium-sulfur batteries, while the drawback that the interlayer will reversely affect the performance of the current collector was ignored. The current collector has a significant influence and contribution to the cycle stability of lithium-sulfur batteries. In this study, we looked into the electrochemical stability and corrosion situation of standard aluminum foil collectors in lithium-sulfur batteries with carbon interlayer. The results show that the introduction of carbon interlayer into the lithium-sulfur batteries will make aluminum foil and carbon paper form an electronic conduction path and galvanic corrosion occurs, accelerating the corrosion of aluminum foil. Therefore, we propose a new corrosion model. During the cycle, the surface of the aluminum collector becomes a non-dense passivation film and lithium polysulfide terminal (ST−1). Then, under the action of the carbon interlayer, the passivation film peels off and the oxide film is attacked by the electrolyte, thiosulfate and polythionate, resulting in pitting holes and ultimately accelerating the corrosion of the aluminum foil collector. This research has some guiding significance for the commercial application of lithium-sulfur batteries.

Beaded CoSe2-C Nanofibers for High-Performance Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are regarded as highly promising energy storage devices due to their high theoretical specific capacity and high energy density. Nevertheless, the commercial application of Li-S batteries is still restricted by poor electrochemical performance. Herein, beaded nanofibers (BNFs) consisting of carbon and CoSe2 nanoparticles (CoSe2/C BNFs) were prepared by electrospinning combined with carbonization and selenization. Benefitting from the synergistic effect of physical adsorption and chemical catalysis, the CoSe2/C BNFs can effectively inhibit the shuttle effect of lithium polysulfides and improve the rate performance and cycle stability of Li-S batteries. The three-dimensional conductive network provides a fast electron and ion transport pathway as well as sufficient space for alleviating the volume change. CoSe2 can not only effectively adsorb the lithium polysulfides but also accelerate their conversion reaction. The CoSe2/C BNFs-S cathode has a high reversible discharge specific capacity of 919.2 mAh g-1 at 0.1 C and presents excellent cycle stability with a low-capacity decay rate of 0.05% per cycle for 600 cycles at 1 C. The combination of the beaded carbon nanofibers and polar metal selenides sheds light on designing high-performance sulfur-based cathodes.

An Organodiselenide Comediator to Facilitate Sulfur Redox Kinetics in Lithium-Sulfur Batteries with Encapsulating Lithium Polysulfide Electrolyte.

Lithium-sulfur (Li-S) batteries are regarded as promising high-energy-density energy storage devices. However, the cycling stability of Li-S batteries is restricted by the parasitic reactions between Li metal anodes and soluble lithium polysulfides (LiPSs). Encapsulating LiPS electrolyte (EPSE) can efficiently suppress the parasitic reactions but inevitably sacrifices the cathode sulfur redox kinetics. To address the above dilemma, a redox comediation strategy for EPSE is proposed to realize high-energy-density and long-cycling Li-S batteries. Concretely, dimethyl diselenide (DMDSe) is employed as an efficient redox comediator to facilitate the sulfur redox kinetics in Li-S batteries with EPSE. DMDSe enhances the liquid-liquid and liquid-solid conversion kinetics of LiPS in EPSE while maintains the ability to alleviate the anode parasitic reactions from LiPSs. Consequently, a Li-S pouch cell with a high energy density of 359 Wh kg-1 at cell level and stable 37 cycles is realized. This work provides an effective redox comediation strategy for EPSE to simultaneously achieve high energy density and long cycling stability in Li-S batteries and inspires rational integration of multi-strategies for practical working batteries.

High-performance MoS2 quantum dots/graphene functionalized separator and its failure analysis under high sulfur loading

Although functionalized separators have been proved to effectively mitigate the shuttle of lithium polysulfides (LiPSs), the capacity degradation of lithium-sulfur (Li-S) batteries with functionalized separators under high sulfur loading still hasn’t been detailed investigated totally. Herein, the synergistic inhibition effect of ultralight MoS2 quantum dots decorated nitrogen doped reduction of graphene oxides composites (MoS2 QDs-NRGO) modified separator on polysulfides shuttling is achieved. The Li-S batteries with this functional separator exhibit an impressive drop in cycle performance under high sulfur loading that the capacity retention at 71.5 % under sulfur loading of 2 mg cm−2, and only 53.1 % under 6 mg cm−2. Through the in-situ/ex-situ Raman spectroscopy investigation, kinetics analysis and electrochemical performance test, we discover that the inhomogeneous deposition of Li2S is seriously on the separator modified layer under high sulfur loading, which blocks the lithium-ion diffusion kinetics in the separator and increases the reaction between Li2S and lithium anode, leading to the fast capacity fading of Li-S batteries. Afterward, we find an appropriate area-loading of the modified layer can effectively mitigate the deposition of the Li2S, thereby improving the cycling stability of Li-S batteries under the high sulfur loading.

WN0.67-Embedded N-doped Graphene-Nanosheet Interlayer as efficient polysulfide catalyst and absorbant for High-Performance Lithium-Sulfur batteries

• A novel interlayer of WN 0.67 @NG for high-performance Li-S batteries is fabricated. • Multifunctional WN 0.67 @NG can be used as efficient polysulfide catalyst and absorbant. • Li-S cell with WN 0.67 @NG/PP delivers outstanding electrochemical performance. • Excellent performance is attributed to synergistic effect of WN 0.67 and nitrogen-doped graphene. Lithium-sulfur (Li-S) battery has attracted wide research attention due to its high energy density, high earth-abundance and low-cost. However, the dissolution of lithium polysulfides (LiPSs) and corresponding shuttle will lead to serious capacity degradation and worse cycling stability of Li-S batteries. To address such issues, herein, we firstly present a novel interlayer of WN 0.67 -embedded N-doped graphene-nanosheets (WN 0.67 @NG) via a facile solvothermal reaction followed by nitriding treatment. The Li-S cell equipped with WN 0.67 @NG modified polypropylene (PP) separator exhibits outstanding electrochemical performances: a long-term stability with only a capacity decay of 0.07% per cycle over 200 cycles and a large capacity of 725 mAh g −1 at 4C; interestingly, a favorable capacity of 776 mAh g −1 can be maintained after 100 cycles at 0.2C for assembled Li-S pouch cell under a high sulfur loading conditions of 4.3 mg cm −2 with lean electrolyte occupation (6 μL mg −1 ). The outstanding performance can be attributed to the following advantages of WN 0.67 @NG interlayer: the high conductivity of NG sheets can facilitate the electron transfer and act as a physical block for restricting the LiPSs shuttle; most importantly, the polar WN 0.67 nanoneedles embedded on the NG sheets not only provide abundant active sites for chemisorption and catalytic conversion of LiPSs, but also contribute to the nucleation and growth of Li 2 S; further theoretical calculations and in-situ Raman spectra clearly reveal the adsorption and catalytic conversion mechanism of WN 0.67 @NG interlayer at the molecular level. The work provides new insight into rational design and facile fabrication of multifunctional separators for industrial applications in high-performance Li-S batteries.

Electrospun CoSe@NC nanofiber membrane as an effective polysulfides adsorption-catalysis interlayer for Li-S batteries

• CoSe@NC nanofiber membrane was synthesized by electrospinning and thermal annealing method. • CoSe nanoparticles have strong adsorption and catalytic capability for polysulfides. • Li-S battery with CoSe@NC nanofiber membrane as interlayer shows excellent electrochemical performance. Lithium sulfur (Li-S) batteries have attracted tremendous attention due to their low cost and high theoretical capacity. However, the serious polysulfides shuttle and slow redox reaction kinetics hinder their large-scale commercial applications. Various attempts have been made to solve the problems. Herein, a CoSe@NC nanofiber membrane was prepared by electrospinning method and used as independent functional interlayer for the Li-S batteries. The visualized adsorption experiments show that the CoSe@NC nanofiber exhibits strong adsorption capability for polysulfides; In addition, CoSe nanoparticles with strong catalytic activity can accelerate the conversion of polysulfides. The adsorption-catalysis synergy of CoSe@NC can therefore effectively enhance the rate performance and cycling stability of Li-S batteries. The cell assembled with CoSe@NC functional interlayer delivers a high initial reversible discharge capacity of 1317 mAh g −1 at 0.1 C rate. After 200 cycles at 1.0 C, the capacity decay rate is only 0.16% per cycle. This work provides a feasible way to promote the electrochemical performance of Li-S batteries

Enhancement of the cycling stability of lithium-sulfur batteries by using a reactive additive for blocking dissolution of lithium polysulfides

Hexamethylene diisocyanate was employed as a reactive additive to capture lithium polysulfides formed at the cathode of lithium-sulfur batteries. Unlike other solid additives used to trap polysulfides through physical and chemical interactions, it could effectively capture lithium polysulfides through chemical reaction between hexamethylene diisocyanate and lithium polysulfides at the electrode–electrolyte interface. A small amount of hexamethylene diisocyanate was enough to completely block the dissolution of lithium polysulfides into liquid electrolyte due to its high chemical reactivity, which enhanced the cycling stability of the lithium-sulfur battery while maintaining its high energy density. Our results demonstrate that the addition of hexamethylene diisocyanate to liquid electrolyte can provide an efficient strategy to address dissolution of lithium polysulfides and achieve good cycling stability in the high energy–density lithium-sulfur batteries.

Fluorinated Graphite (FG)-Modified Li-S Batteries with Superhigh Primary Specific Capacity and Improved Cycle Stability.

Lithium-sulfur (Li-S) batteries have received extensive attention because of their high theoretical energy density and low cost. However, the low sulfur utilization and the shuttle effect of polysulfide cause low initial capacity and serious capacity decay. Herein, fluorinated graphite (FG) is introduced to the cathode to alleviate these issues. The results indicated that the FG could provide additional capacity during the first discharge process and increase the porosity and polarity of the cathode via in situ formation of lithium fluoride (LiF) nanocrystals, which can enhance the infiltration of electrolyte and polysulfide adsorption. As a result, the as-prepared cathode containing FG shows a high initial specific capacity of 1602 mA h g-1 and the reversible specific capacity is 650 mA h g-1 at 0.5C after 300 cycles. Moreover, its specific capacity remains at 860 mA h g-1 at 5C, which is 367% higher than that of the sample without FG. This paper provides a new strategy to improve the energy density and the cycle stability of Li-S batteries.

Rational design of Ni3(HITP)2@GO composite for lithium-sulfur cathode

Lithium-sulfur batteries have attracted much attention due to their low cost, environment-friendliness, and high energy density. However, it is hard to get a satisfactory performance due to the low conductivity of sulfur, the volume changes from sulfur to lithium sulfides during the cycling, and the shuttle effect of the intermediate product of polysulfides. Here, we propose a sulfur host material based on the composite of conductive metal–organic frameworks (Ni3(HITP)2) and graphene oxide. This composite material combines the unique pore structure of Ni3(HITP)2 and the improved conductivity. The stacked one-dimensional channels could effectively improve the utilization of S, and the good conductivity could enhance the charge transfer of the electrode. The rich Lewis acid sites of Ni3(HITP)2 could effectively adsorb the polysulfides around the open metal sites that help suppress the shuttle effects. This rational design improves the rate performance and cycle stability of lithium-sulfur batteries.

Decoration of carbon nanofibers with bimetal sulfides as interlayer for high performance lithium-sulfur battery

In order to obtain high-performance lithium-sulfur (Li-S) batteries, the rapid capacity loss caused by the notorious polysulfide shuttle effect is an urgent challenge to be solved. It is widely reported that polysulfides are trapped in electrolytes due to the strong chemisorption of polar materials in Li-S batteries. Here, a free-standing NiCo2S4 nanoparticles decorated carbon nanofibers (NiCo2S4-CNFs) interlayer is prepared via electrospinning and simple hydrothermal method for the application in Li-S batteries. Three-dimensional carbon fibers (CNFs) skeleton builds a highly conductive carbon network, which provides a large quantities of transmission paths for electrons and ions. Uniformly distributed NiCo2S4 nanoparticles act as an absorbent of the long-chain lithium polysulfides (LiPSs) and a catalyst to accelerate the conversion of sulfur species. Meticulous designed NiCo2S4-CNFs interlayer significantly improves the capacity retention rate and cycle stability of Li-S batteries. It supplies an initial specific capacity of 1421 mAh g−1 at 0.1 C, and its capacity remains at 918 mAh g−1 after 200 cycles at 0.2 C. Even at a high current density of 1 C, it still possesses a reversible specific capacity of 515 mAh g−1 after 500 cycles and extremely low capacity decay of 0.06% per cycle. More importantly, the NiCo2S4-CNFs interlayer still delivers excellent electrochemical performance with a higher sulfur loading of 4.5 mg cm−2, which verifies its huge commercial application potential.

Yolk@Shell Structured MnS@Nitrogen-Doped Carbon as a Sulfur Host and Polysulfide Conversion Booster for Lithium/Sodium Sulfur Batteries

Lithium-sulfur (Li-S) batteries have been regarded as an important candidate for next-generation energy storage devices due to their low cost and high theoretical energy density. However, several factors retard the practical use of Li-S batteries including the slow kinetics of lithium polysulfide (LiPS) transformation as well as the shuttle effect induced by the diffusion of LiPS that damages the cycling stability of Li-S batteries. In this study, a yolk@shell structured MnS@nitrogen-doped carbon (MnS@N-C) is developed as the S host and polysulfide conversion booster, which offers both the physical confinement of S species and accelerated kinetics toward LiPS catalytic conversion. As a result, the developed S/yolk@shell MnS@N-C delivers a higher rate performance compared to S/yolk@shell MnO@N-C and S/N-C and long cycle life with a remaining capacity of 636.1 mAh g–1 after 330 cycles at 0.5C. When equipped with MnS@N-C functional separators, S/yolk@shell MnS@N-C retains a capacity of 504.2 mAh g–1 after 1000 cycles at 1C. In addition, S/yolk@shell MnS@N-C also delivers a decent capacity decay of 0.16% per cycle after 300 cycles at 0.5C in a room-temperature Na-S battery.