Conversion Of Lithium Polysulfides Research Articles

Rapid Growth of Bi2Se3 Nanodots on MXene Nanosheets at Room Temperature for Promoting Sulfur Redox Kinetics.

Li-S batteries are hampered by problems with their cathodes and anodes simultaneously. The improvement of Li-S batteries needs to consider both the anode and cathode. Herein, a Bi2Se3@MXene composite is prepared for the first time by rapidly growing Bi2Se3 nanodots on two-dimensional (2D) MXene nanosheets at room temperature through simply adding high-reactive hydroxyethylthioselenide in Bi3+/MXene aqueous solution. Bi2Se3@MXene exhibits a 2D structure due to the template effect of 2D MXene. Bi2Se3@MXene can not only facilitate the conversion of lithium polysulfides (LiPSs) but also inhibit their shuttling in the S cathode due to its catalytic effect and adsorption force with LiPSs. Bi2Se3@MXene can also be used as an interfacial lithiophilic layer to inhibit Li dendrite growth in the Li metal anode. Theoretical calculations reveal that Bi2Se3 nanodots in Bi2Se3@MXene can effectively boost the adsorption ability with LiPSs, and the MXene in Bi2Se3@MXene can accelerate the electron transport. Under the bidirectional regulation of Bi2Se3@MXene in the Li metal anode and S cathode, the Li-S battery shows an enhanced electrochemical performance.

Multifunctional tri-layer aramid nanofiber composite separators for high-energy-density lithium-sulfur batteries

Lithium-sulfur (Li-S) battery has attracted much attention due to their high theoretical energy density. However, severe shuttling effect, sluggish reaction kinetics and uncontrolled dendrite formation of Li anode greatly deter their practical applications. Different to conventional separator engineering strategies that are always focused on surface coating of functional interlayer on commercial polyolefin separators, herein, we proposed a structural engineering tactic by rationally tuning the porous structure and composition of the p-aramid nanofiber (ANF) composite separator to address simultaneously the above problems. A two-step film-casting process combined with a phase inversion approach was developed to fabricate a multifunctional tri-layer ANF composite separator. This innovative separator was especially engineered to comprise a conductive and catalytic NiFe2O4 modified multi-walled carbon nanotubes/ANF layer for rapid and efficient conversion of lithium polysulfides, a microporous ANF layer for fast ion transport, and a dense nanoporous ANF layer for lithium dendrite inhibition. This tri-layer ANF-based separator possessed high porosity, excellent thermal stability, and superb electrolyte wettability. Batteries with the tri-layer ANF- based separator exhibited outstanding cyclic stability with high capacity of >3 mAh cm−2 at high sulfur loading (4 mg cm−2) and high current density (4 mA cm−2). This work opens up new opportunities for design of functional separators based on high performance polymers using the structural engineering strategy.

Regulating the P-band center of SnS2-SnO2 heterostructure to boost the redox kinetics for high-performance lithium-sulfur battery

Lithium-sulfur batteries (LSBs) are considered a strong contender for the new-generation secondary energy storage system due to their high capacity and energy density. However, the sluggish reaction kinetics and the shuttle effect of lithium polysulfides (LPSs) severely hinder the cycle stability. The robust design of both the separator and cathode exhibit an effective role in restricting the shuttle effect and accelerating redox kinetics through the LPSs trapping and catalyzing effect. In this paper, a CNT-modified tin sulfide and tin oxide (SnS2-SnO2-CNTs) heterostructure was constructed as a multifunctional catalyst to modify both the separator and cathode to achieve high-performance LSBs. The formation of SnS2-SnO2 heterostructure promotes the movement of the P band center of the tin atom to the Fermi level, which realizes the association process of adsorption, capture, and conversion of LPSs, thus effectively suppressing the shuttle effect. The SnS2-SnO2 heterogeneous interface can also reduce the deposition barrier of Li2S, thus greatly promoting the redox kinetics. Together with the improved electron transfer, the resulting LSBs with the robust electrode and separator exhibit superior electrochemical performance with a high initial capacity of 930.2 mAh g−1 at 1 C with a high sulfur loading of 4.3 mg cm−2 and a remarkable capacity of up to 580.3 mAh g−1 at an ultrahigh rate of 7.4 C.

MOF-Derived CeO2 Nanorod as a Separator Coating Enabling Enhanced Performance for Lithium-Sulfur Batteries.

The deployment of Li-S batteries in the commercial sector faces obstacles due to their low electrical conductivity, slow redox reactions, quick fading of capacity, and reduced coulombic efficiency. These issues stem from the "shuttle effect" associated with lithium polysulfides (LiPSs). In this work, a haystack-like CeO2 derived from a cerium-based metal-organic framework (Ce-MOF) is obtained for the modification of a polypropylene separator. The carbon framework and CeO2 coexist in this haystack-like structure and contribute to a synergistic effect on the restriction of LiPSs shuttling. The carbon network enhances electron transfer in the conversion of LiPSs, improving the rate performance of the battery. Moreover, CeO2 enhances the redox kinetics of LiPSs, effectively reducing the "shuttle effect" in Li-S batteries. The Li-S battery with the optimized CeO2 modified separator shows an initial discharge capacity of 870.7 mAh/g at 2 C, maintaining excellent capacity over 500 cycles. This research offers insights into designing functional separators to mitigate the "shuttle effect" in Li-S batteries.

Layered double Hydroxides-MXene heterointerfaces with abundant anion vacancies expediting sulfur redox kinetics for High‑Performance Lithium–Sulfur batteries

Lithium-sulfur batteries (LSBs) are increasingly seen as advanced battery systems of great promise, owing to their exceptional energy density and cost-effectiveness. Yet, designing efficient electrocatalysts that can both effectively mitigate the diffusion of soluble lithium polysulfides (LiPSs) and enhance redox kinetics still remains a significant challenge, particularly at high sulfur loadings and lean electrolyte conditions. In this work, we develop NiCo-layered double hydroxides (NiCo-LDHs) nanosheets featuring abundant oxygen vacancies (Vo), anchored on Ti3C2-MXene nanosheets (denoted as Vo-LDHs-MXenes), tailored specifically for high-performance LSBs. The heterointerfaces between MXenes and Vo-LDHs modify the electronic structure and enhance the catalytic activity of the LDHs and MXenes, yielding multifunctional synergistic effects. Our theoretical and electrochemical analyses indicate that the Vo-LDHs-MXenes heterostructures exhibit enhanced affinity for LiPSs and superior catalytic performances compared to individual LDHs. This improvement facilitates the efficient adsorption and conversion of LiPSs, as well as the nucleation and decomposition of Li2S. Consequently, the cell with the Vo-LDHs-MXenes modified separator delivers stable cycling performances with a high initial specific capacity of 938.9 mAh/g over 300cycles at 1.0C and good rate capabilities. Notably, it still achieves a high initial areal capacity of 6.09 mAh cm−2 under a high sulfur loading of 6.7 mg cm−2 and low electrolyte/sulfur (E/S) ratio of 6.0 μL mg−1 over 50cycles.

N doped carbon supported cobalt/tungsten nitride Mott−Schottky heterojunction as an efficient electrocatalyst to enhance adsorption and conversion of lithium polysulfides for high-performance lithium–sulfur batteries

Lithium–sulfur batteries (LSBs) suffer from the dissolution of lithium polysulfides (LiPSs) which leading to capacity degradation and poor cycling stability. Hence, weʼve developed the Co/W3N4@NC Mott–Schottky heterostructures with built in electric field (BIF) are prepared as catalyst model to generate a built-in electric field to enhance the electrocatalytic effect on sulfur electrochemistry. Theoretical and experimental results have jointly demonstrated that the redistribution of charge and the presence of a built-in electric field at the Co/W3N4@NC heterointerface can promote the redox reaction within lithium sulfur battery during the discharge and charge processes, respectively. Experimental tests have confirmed its outstanding reversibility, achieving a capacity of 793.2 mAh·g−1 over 500 cycles at 1 C. It also shows excellent cycling performance with only 0.05 % attenuation per cycle over 800 cycles at 2 C for LSBs. Furthermore, even with a high sulfur loading of 5.5 mg·cm−2, the S@ Co/W3N4@NC cathode maintains favorable sulfur-related electrochemistry and delivers a high areal capacity of 3.61 mAh·cm−2 as well as maintaining considerable stability. This synthetic Mott–Schottky heterostructure not only amplifies the electrocatalytic effect in LSBs, but also advances the design of catalysts for advanced high-energy-density batteries.

Development of Synergistically Efficient Ni–Co Pair Catalytic Sites for Enhanced Polysulfide Conversion in Lithium–Sulfur Batteries

AbstractThe performance of Lithium–sulfur (Li–S) batteries is constrained by the migration of lithium polysulfide (LiPS), the slow conversion of LiPS, and the significant reaction barrier encountered during the precipitation/dissolution of Li2S throughout the discharge/charge cycle. In this contribution, the study presents Ni–Co dual‐atom catalytic sites on hollow nitrogen‐doped carbon (NiCoNC). Theoretical calculations and experimental data reveal that the dual‐atom catalysts (DACs) accelerate the kinetic conversion of LiPSs and facilitate the formation/decomposition of Li2S during discharging and charging, which minimizes LiPS migration. Consequently, the utilization of S/NiCoNC cathodes manifests a substantial initial capacity of 1348.5 mAh g−1 at 0.1 C, exceptional cycling stability with an average capacity degradation rate of 0.028% per cycle over 900 cycles at 0.5 C, and noteworthy rate capability with a capacity of 626 mAh g−1 at 2 C. Electrodes with a higher sulfur loading of 4.5 mg cm−2 and a low electrolyte/sulfur ratio of 8 µL mg−1 exhibit exceptional specific capacities of up to 1236 mAh g−1 at 0.1 C, as well as noteworthy capacity retention of 494.2 mAh g−1 after 200 cycles at 0.2 C. This study effectively showcases the potential of DACs as catalysts for sulfur cathodes, thereby enhancing the overall performance of Li–S batteries.

Pinpointing the Cl Coordination Effect on Mn-N3-Cl Moiety Toward Boosting Reaction Kinetics and Suppressing Shuttle Effect in Li-S Batteries.

Single atom catalysts (SACs) are highly favored in Li-S batteries due to their excellent performance in promoting the conversion of lithium polysulfides (LiPSs) and inhibiting their shuttling. However, the intricate and interrelated microstructures pose a challenge in deciphering the correlation between the chemical environment surrounding the active site and its catalytic activity. Here, a novel SAC featuring a distinctive Mn-N3-Cl moiety anchored on B, N co-doped carbon nanotubes (MnN3Cl@BNC) is synthesized. Subsequently, the selective removal of the Cl ligands while inheriting other microstructures is performed to elucidate the effect of Cl coordination on catalytic activity. The Cl coordination effectively enhances the electron cloud density of the Mn-N3-Cl moiety, reducing the band gap and increasing the adsorption capacity and redox kinetics of LiPSs. As a modified separator for Li-S batteries, MnN3Cl@BNC exhibits high capacities of 1384.1 and 743mAhg-1 at 0.1 and 3C, with a decay rate of only 0.06% per cycle over 700cycles at 1C, which is much better than that of MnN3OH@BNC. This study reveals that Cl coordination positively contributes to improving the catalytic activity of the Mn-N3-Cl moiety, providing a fresh perspective for the design of high-performance SACs.

Ribosome-inspired electrocatalysts inducing preferential nucleation and growth of three-dimensional lithium sulfide for high-performance lithium-sulfur batteries

Nucleation of lithium sulfide (Li2S) induced by electrocatalysts plays a crucial role in mitigating the shuttle effect. However, short-chain polysulfides on electrocatalysts surfaces tend to re-dissolve into electrolytes, delaying Li2S supersaturation and its nucleation. In this study, we draw inspiration from the ribosome-driven protein synthesis process in cells to prepare ultrasmall nitrogen-doped MoS2 nanocrystals anchored on porous nitrogen-doped carbon networks (N-MoS2-NC) electrocatalysts. Excitedly, the ex-situ SEM demonstrates that ribosome-inspired N-MoS2-NC electrocatalysts induce early nucleation and rapid growth of three-dimensional Li2S during discharge. Theoretical calculations reveal that the Li-S bond length in N-MoS2-Li2S(100) is shorter, and the corresponding interfacial formation energy is lower than in MoS2-Li2S(100). This accelerated conversion of lithium polysulfides to Li2S can enhance the utilization of active substances and inhibit the shuttle effect. This study highlights the potential of ribosome-inspired N-MoS2-NC in improving the electrochemical stability of Li-S batteries, providing valuable insights for future electrocatalyst design.

First-principles study of the catalytic performance of sulfur cathode host Co3Mo3N

Lithium-sulfur (Li-S) batteries is a promising battery system for next-generation energy storage systems due to their high theoretical specific capacity, energy density, low cost, and environmental friendliness. Co3Mo3N can effectively anchor and catalyze the conversion of lithium polysulfides (LiPSs), thereby accelerating electrochemical reaction kinetics and giving LiPSs outstanding electrochemical properties. This work simulates the effect of LiPSs on the surface of Co3Mo3N(111) through first-principles calculations. This interaction between sulfur and metal occurs, forming covalent bonds. Co3Mo3N(111) surface adsorbs Li2S, which the Co-Mo bridge site has the lowest energy and is the best adsorption site. LiPSs were placed on the surface of Co3Mo3N(111) in two ways: horizontally and vertically. Co3Mo3N can adsorb and catalyze LiPSs in both extreme adsorption states. The horizontal adsorption position has better adsorption catalytic ability for LiPSs. This work provides theoretical support for the good catalytic effect of Co3Mo3N on LiPSs, and is expected to promote the use and development of bimetallic nitrides in lithium-sulfur batteries.

Nitrogen-doped carbon nanofiber loaded MOF-derived NiCo bimetallic nanoparticles accelerate the redox transformation of polysulfide for lithium- sulfur batteries

In the electrochemical study of lithium-sulfur (Li-S) batteries, the slow kinetics of the sulfur reduction reaction (SRR) leading to severe shuttle effect of polysulfides remains a major challenge. Catalysts with bimetallic nanoparticles have higher adsorption affinity for lithium polysulfides and hold great potential in improving reaction kinetics. In this study, a nitrogen-doped carbon nanofiber carrier was prepared using high-voltage electrospinning technology, and through in-situ growth and high-temperature pyrolysis process, the carrier material was uniformly loaded with active sites of NiCo bimetallic nanoparticles derived from Metal-organic framework (MOF), aiming to improve the kinetics of sulfur oxidation and reduction and reduce the severe shuttle effect of soluble polysulfides. At the same time, polymethyl methacrylate was added to adjust the pore structure of the carbon nanofibers to form an ideal independent sulfur cathode porous conductive carbon network for rapid ion transport to prevent Li2S deposition and alleviate the volume change during lithiation/delithiation process. Experimental results show that the synergistic catalytic effect of bimetallic nanoparticles can not only rapidly anchor lithium polysulfides throughout the entire reaction process of Li-S batteries, but also reduce the resistance during the reaction process, accelerating the conversion of lithium polysulfides to Li2S deposition. It demonstrates outstanding electrochemical performance, with a first-cycle discharge specific capacity as high as 1431.7 mAh g−1 at a 0.2 C rate, and a Coulombic efficiency of 96%. After 500 cycles, its capacity still maintains at 628.5 mAh g−1, with a decay rate of only 0.11% per cycle. This study provides a feasible insight into the synergistic catalysis of MOF-derived metal nanoparticles, which has important guiding significance and potential impact on the catalysis of Li-S batteries by bimetallic nanoparticles with an independent sulfur cathode structure, and is expected to accelerate the industrialization process of Li-S batteries.

Juice Vesicles Bioreactors Technology for Constructing Advanced Carbon-Based Energy Storage.

The construction of high-quality carbon-based energy materials through biotechnology has always been an eager goal of the scientific community. Herein, juice vesicles bioreactors (JVBs) bio-technology based on hesperidium (e.g., pomelo, waxberry, oranges) is first reported for preparation of carbon-based composites with controllable components, adjustable morphologies, and sizes. JVBs serve as miniature reaction vessels that enable sophisticated confined chemical reactions to take place, ultimately resulting in the formations of complex carbon composites. The newly developed approach is highly versatile and can be compatible with a wide range of materials including metals, alloys, and metal compounds. The growth and self-assembly mechanisms of carbon composites via JVBs are explained. For illustration, NiCo alloy nanoparticles are successfully in situ implanted into pomelo vesicles crosslinked carbon (PCC) by JVBs, and their applications as sulfur/carbon cathodes for lithium-sulfur batteries are explored. The well-designed PCC/NiCo-S electrode exhibits superior high-rate properties and enhanced long-term stability. Synergistic reinforcement mechanisms on transportation of ions/electrons of interface reactions and catalytic conversion of lithium polysulfides arising from metal alloy and carbon architecture are proposed with the aid of DFT calculations. The research provides a novel biosynthetic route to rational design and fabrication of carbon composites for advanced energy storage.

Mesoporous NiCo2S4@rGO nanocomposites as sulfur carriers for high performance lithium sulfur batteries

It is of unprecedented significance to surmount the daunting challenges of lithium-sulfur battery due to its low cost and exceptionally high energy density. Herein, the mesoporous NiCo2S4@rGO nanocomposites were fabricated solvothermally with mesoporous NiCo2S4 nanoparticles dispersed on rGO and investigated as highly-efficient carriers for sulfur cathode in lithium-sulfur battery. The as-obtained NiCo2S4@rGO nanocomposites are featured with abundant mesopore, good electronic and ionic conductivity, excellent catalytic effect on the redox of lithium polysulfides conversion and strong adsorption, thus observably accelerating the redox kinetics of lithium polysulfides and suppressing the shuttle effect. Therefore, the NiCo2S4@rGO@S electrode delivers a high reversible specific discharge density of 785 mAh g−1 at 0.1 C after 100 cycles and exhibits good rate capability and cycling stability, verifying its great promising for the commercial application of lithium-sulfur battery.

Tailoring Interfacial Electric Field by Gold Nanoparticles Enable Electrocatalytic Lithium Polysulfides Conversion for Lithium-Sulfur Batteries.

Although lithium-sulfur batteries (LSBs) are considered as the promising next rechargeable storage system ascribing to their decent specific capacity of inorganic sulfur, the development is partially impeded by inferior electronic conductivity, severe shuttle effect, and large volume variation. To tackle the issues above, a great deal of effort is made on sulfur-containing polymer (SCP) that shows better electrochemical performance. Nevertheless, sluggish conversion of lithium polysulfides (LiPSs) obstructs battery performance yet. Herein, electrocatalytic LiPSs with full conversion by tailoring the interfacial electric field are discovered based on gold nanoparticles (AuNPs) anchored on sulfurized polyaniline (SPANI). A downhill path of Gibbs free energy from organosulfur polymer to intermediate product means more spontaneously and favorable for full conversion, as the significant enhancement of electron density of state in the vicinity of the HOMO level for the AuNPs increase the electron transition probability rate. This composite delivers satisfactory electrochemical performance, especially increased rate capacity of >300 mAh g-1 . Furthermore, catalyst mechanism on molecule level is proposed that AuNPsdominate chemical enhancement and higher electron delocalizablility betweenAuNPs and LiPSs molecules. These results can erect a promising strategy for enhancing lithium polysulfides full conversion.

Ni-Ce bimetal doping and phosphating modulated MOF with improved catalysis and adsorption for high-performance lithium-sulfur battery applications

Lithium-sulfur batteries (LSBs) have received widespread attentions because of high specific capacity and low cost. However, the low sulfur utilization and shuttle effect limited their wide application. In this paper, phosphating Ni-Ce bimetallic nanoparticles embedded in multifunctional freestanding porous carbon with improved catalytic activity and confinement were prepared from MOF materials. Compared with monoatomic catalysts or other homonuclear diatomic mixtures, the catalytic-adsorptive synergistic effect of Ni-Ce doping in NiCe@CPS can provide more active sites to catalyze the conversion of lithium polysulfides (LiPSs) to improve the reaction kinetics effectively, meanwhile, the phosphides Ni2P and CeP can physically and chemically adsorb the LiPSs to further inhibit the shuttle effect. Moreover, the porous carbon structure not only provides abundant channels for Li+ transport and electrolyte permeation but greatly facilitates sulfur storage and mitigates the volume expansion during the cycling process. The battery assembled with NiCe@CPS cathode delivered a discharge-specific capacity of 1013 mAh g−1 at 0.1 C, and maintained 768 mAh g−1 after 100 cycles with a Coulombic efficiency of 95 %.

Thermal conductive aramid nanofiber/surface-decorated alumina microsphere composite separator

The development of lithium-sulfur (Li–S) batteries is hindered by inhomogeneous Li plating and irreversible loss of active materials. In this work, a thermal conductive and electrocatalytic aramid nanofiber (ANF) composite separator containing surface-decorated alumina (Al2O3) microspheres is prepared through a simple filtration approach using ZnO nanosheets decorated Al2O3 microspheres (Al2O3@ZnO) as the thermal conductive filler and electrocatalyst. Compared with the separators fabricated by surface modification of commercial polyolefin separators, the as-prepared ANF/Al2O3@ZnO composite separator features homogeneous compositions and ensures uniform thermal distribution in both the through-plane and in-plane directions of the membrane. By rationally designing the structure of Al2O3@ZnO and adjusting the mass ratio of Al2O3@ZnO to ANF, excellent thermal conduction networks are formed by overlapping the ZnO nanosheets. Hence, the prepared ANF/Al2O3@ZnO composite separator possesses higher thermal conductivity than ANF/Al2O3 composite separator, which benefits uniform thermal distribution and homogeneous Li plating within the battery. Moreover, the electrocatalytic ZnO nanosheets catalyze the conversion of lithium polysulfides, efficiently inhibiting the shuttle effect and improving sulfur utilization. When subjected to a temperature gradient, the ANF/Al2O3@ZnO composite separator assembled cells display high initial capacity, low decay rate, and superb cycle stability. This novel composite separator integrates both thermal conductive and electrocatalytic functional components with the heat-resistant ANF matrix, offering a new design strategy of separator towards high-performance Li–S batteries.

Concurrent hetero-/homo-geneous electrocatalysts to bi-phasically mediate sulfur species for lithium–sulfur batteries

Expediting redox kinetics of sulfur species on conductive scaffolds with limited charge accessible surface is considered as an imperative approach to realize energy-dense and power-intensive lithium-sulfur (Li–S) batteries. In this work, the concept of concurrent hetero-/homo-geneous electrocatalysts is proposed to simultaneously mediate liquid–solid conversion of lithium polysulfides (LiPSs) and solid lithium disulfide/sulfide (Li2S2/Li2S) propagation, the latter of which suffers from sluggish reduction kinetics due to buried conductive scaffold surface by extensive deposition of Li2S2/Li2S. The selected model material to verify this concept is a two-in-one catalyst: carbon nanotube (CNT) scaffold supported iron-cobalt (Fe-Co) alloy nanoparticles and partially carbonized selenium (C-Se) component. The Fe-Co alloy serves as a heterogeneous electrocatalyst to seed Li2S2/Li2S through sulphifilic active sites, while the C-Se sustainably releases soluble lithium polyselenides and functions as a homogeneous electrocatalyst to propagate Li2S2/Li2S via solution pathways. Such bi-phasic mediation of the sulfur species benefits reduction kinetics of LiPS conversion, especially for the massive Li2S2/Li2S growth scenario by affording an additional solution directed route in case of conductive surface being largely buried. This strategy endows the Li–S batteries with improved cycling stability (836 mA h g−1 after 180 cycles), rate capability (547 mA h g−1 at 4 C) and high sulfur loading superiority (2.96 mA h cm−2 at 2.4 mg cm−2). This work hopes to enlighten the employment of bi-phasic electrocatalysts to dictate liquid–solid transformation of intermediates for conversion chemistry batteries.

Ni0.85Se/NiSe2-C electrocatalyst with defect engineering and heterostructure for the multifunctional acceleration of lithium polysulfide conversion

Reasonably designed sulfur cathode materials are one of the effective ways to solve the shuttle effect of lithium polysulfide (LiPSs) and the sluggish electrochemical reaction kinetics of lithium-sulfur batteries (LSBs), in which the defect engineering and multi-component heterostructures design has received extensive attention. In this work, a composite material of Ni0.85Se/NiSe2 decorating carbon tubes (N0.85S/NS2-C) with cation vacancy and heterostructure was successfully constructed. The experimental results confirm that the Ni0.85Se cation vacancies and Ni0.85Se/NiSe2 heterostructure enhance the intrinsic catalytic activity and the chemisorption capacity toward LiPSs, reduce the nucleation barrier of Li2S, and accelerate the electrochemical reaction kinetics. Simultaneously, the carbon tubes improve the electronic conductivity of the sulfur electrode and inhibit the agglomeration of Ni0.85Se/NiSe2 nanoparticles. By incorporating both heterostructure and cation vacancy, efficient multifunctional coupling of adsorption-catalysis-conversion toward LiPSs is achieved. The N0.85S/NS2-C/S electrode exhibited satisfactory electrochemical performance, it delivered a low-capacity attenuation of 0.083 % per cycle during 450 cycles at 1 C. Under a sulfur loading of 2.9 mg cm−2, a high initial specific discharge capacity of 1126 mA h g−1 can be obtained at 0.1 C rate. This work will provide a feasible scheme and new ideas for the designing of multifunctional coupling sulfur host materials for efficient LSBs.

Building composite of layered yttrium hydroxide and carbon nanotube as the sulfur host for high-performance lithium‑sulfur batteries

The commercialization of lithium‑sulfur batteries is still confronting with great challenges due to the sluggish redox kinetics of sulfur and the shuttle effect of lithium polysulfides (LiPS). Herein, two-dimensional (2D) layered yttrium hydroxide (LYH) nanosheets are in-situ grown on multiwalled carbon nanotubes (CNTs) and used as a multifunctional host material (LYH@CNT) for sulfur loading. The crosslinked CNTs provide a robust and conductive network for quick charge transfer and sufficient active site exposure, while LYH nanosheets demonstrate strong ability for anchor and catalytic conversion of lithium polysulfides. The theoretical calculation and adsorption experiment also confirm the strong adsorption of LYH for lithium polysulfides. Therefore, sulfur loaded on LYH@CNT exhibits excellent electrochemical performance, such as a good cycling stability with a capacity of 484 mAh g−1 after 800 cycles at 2C. This study opens a new avenue in the development of advanced sulfur hosts for lithium‑sulfur batteries.

In situ reduction growth Sn-MoS2 on CNFs as advanced separator coating for improved-performance lithium sulfur batteries

Separator modification is a promising strategy to solve the issues of terrible “shuttle effect” and sluggish conversion of lithium polysulfides (LiPSs) in Lithium-sulfur batteries (LSBs). Herein, we fabricated an intriguing architecture of tin-molybdenum disulfide (Sn-MoS2) heterostructure uniformly distributed on carbon nanofibers (Sn-MoS2/CNFs) by the incorporation of electrospinning technology and the in-situ reduction methods to modify the separator for LSBs. The Sn reduced from tin oxide (SnO2) in carbon nanofiber can not only facilitate the rapid ion and electron migration but also promote the porous structure obtained by the reduction collapse process. Furthermore, the heterostructure of MoS2 and Sn uniformly and stably dispersed on the carbon nanofiber and effectively served as both chemical adsorption carriers and electrocatalysts to enhance the LiPSs anchoring and the conversion reaction kinetics. In result, the initial discharge specific capacity at 0.2 C can achieve 1332.8 mAh g−1, while the capacity remains at 579.3 mAh·g−1 after 200 cycles for the LSBs with the Sn-MoS2/CNFs separators. We believe that the experimental results offer a feasible method to design high-performance separators for LSBs.