Conversion Of Lithium Polysulfides Research Articles

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.

Carbon nanotubes integrated with multiphasic molybdenum diselenide nanosheets as hybrid membrane accomplish highly efficient electrocatalysts for lithium-sulfur batteries

Lithium sulfur (Li-S) batteries are considered a promising application device due to their high theoretical capacity and energy density. However, the commercialization of Li-S batteries is hindered by the rapid capacity fading caused by the shuttle effect of lithium polysulfide (LiPSs) and the sluggish redox reaction of sulfur cathodes. To address these issues, the hybrid membrane with combination of multiphasic molybdenum diselenide nanosheets (MMS) modified carbon nanotubes (MMS@CNTs) and utilized Li2S6 catholyte for Li-S batteries. The conductivity CNTs facilitate fast electronic/ionic transport, while the polarity of MMS has a strong affinity for LiPSs, effectively anchoring them, facilitating the redox conversion of lithium polysulfides, and effectively diminishing reaction barriers. The cell with MMS@CNTs displays an initial discharge capacity of 1036.2 mAh g−1 and maintains 810.5 mAh g−1 after 300 cycles at 0.2 C with 5.4 mg sulfur loading. Remarkably, even at 10.8 mg sulfur loading, the MMS@CNTs membrane displays high capacity of 8.1 mAh and maintains 6.7 mAh over 100 cycles. The results show that the efficient chemical anchoring polysulfides and catalyzing redox reaction by multifunctional MMS@CNTs hybrid composites is promising for assembling with a high sulfur loading electrode, which exhibits a superior electrochemical performance in Li-S batteries.

Constructing Co/CoV2O6 tandem catalytic heterostructure to enhance lithium polysulfide conversion in lithium-sulfur batteries

The “shuttle effect” caused by polysulfide (LiPSs) dissolution and diffusion is a great challenge for sulfur (S) cathode in lithium-sulfur batteries (LSBs). Herein, we have successfully constructed Co/CoV2O6 tandem catalytic heterostructure anchored by N-doped carbon (Co/CoV2O6/NC) via an impregnation-assisted pyriaolysis method. The “adsorption-transfer-conversion” tandem catalytic mechanism for LiPSs is realized by utilizing the three behaviors of the strong chemical adsorption of CoV2O6 to LiPSs, the strong conversion of Co to LiPSs, and the transport effect of CoV2O6←Co interfacial built-in electric field to polysulfide ions. This can effectively suppress the “shuttle effect” by separating the adsorption and conversion process of LiPSs at different active sites. The tandem catalytic characteristic coupled with the interfacial Co-N and V-N bonds among Co, CoV2O6 and NC, the high electrical conductivities of metal Co and NC conducting network, the hierarchical porous structure of polyhedral framework, collectively endow Co/CoV2O6/NC@S cathode with strong structural stability, weak electrochemical polarization, good electrochemical reversibility and fast electrochemical kinetics. As a result, Co/CoV2O6/NC@S cathode presents the significantly enhanced electrochemical performance with a high capacity of 558.4 mAh g−1 at 0.2 C after 100 cycles and a low-capacity decay rate of 0.123% per cycle during 300 cycles at 1 C.

MOF-derived Co–Mo bimetallic heterostructures for the selective trapping and conversion of polysulfides in lithium–sulfur batteries

Hollow CoSx/MoO3 derived from ZIF-67 shows preferred selective trapping and conversion of LiPSs as a modified separator material for LSBs.

Encapsulating CoRu alloy nanocrystals into nitrogen-doped carbon nanotubes to synergistically modify lithium-sulfur batteries separator

Lithium-sulfur batteries (LSBs) have attracted considerable attention owing to their large energy density and abundant reserves of sulfur element. However, the sluggish kinetics and shuttle effects.seriously inhibit the further application of LSBs. Extensive studies have conclusively demonstrated that separator modification was an effective strategy to enhance LSBs properties through the chemical adsorption and catalytic kinetic conversion of lithium polysulfides (LiPSs). In this study, cobalt and ruthenium nanoalloys confined into nitrogen-doped carbon nanotubes (CoRu@N-CNTs) were prepared by one-step annealing method using melamine as carbon source. The obtained CoRu@N-CNTs exhibit plenty of advantages, including abundant CoRu bimetallic catalytical and nitrogen adsorption active sites, exceptional electrolyte wettability and high conductivity. Thanks to these merits, the CoRu@N-CNTs can provide ultrafast ion transfer channels, lots of anchoring for LiPSs and the catalytic conversion kinetics of LiPSs. When applied to modify Li–S batteries separator, the CoRu@N-CNTs modified separator presented an excellent initial specific capacity of 1134.22 mAh g−1 at 0.5C, good rate performance (686 mAh g−1 at 3C) and outstanding cycle performance with a capacity attenuate rate of only 0.107 % per cycle for 400 cycles. Furthermore, when the current density increased to 1C (S loading of 1.344 mg), it displayed a superior capacity attenuation rate of 0.09 %. When the S loading increased to 2.304/3.072 mg, it also demonstrated an outstanding cycle performance. This work provides a feasible strategy to modify the Li–S battery separator through synergistic integration of catalytic conversion and chemisorption of polysulfides.

A Universal MOF‐Confined Strategy to Synthesize Atomically Dispersed Metal Electrocatalysts Toward Fast Redox Conversion in Lithium‐Sulfur Batteries

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

The introduction of metallic Cu onto mixed-phase TiO2 to realize in-situ capture, conversion, and reuse of lithium polysulfides for Li-S batteries

The Li-S batteries possessing high theoretical energy density are promising for next-generation energy storage. However, the shuttle effect and slow conversion of lithium polysulfides seriously hinder the practical application. In this contribution, introducing metallic Cu to modify dual-phase TiO2 (rutile/anatase) grown on N-doped carbon nanosheets (denoted as Cu/mTiO2-NC) can act as a buffer layer to confine the active S species in the cathode region effectively. The corresponding systematic experiments show that the Cu/mTiO2-NC provides sufficient surface affinity to adsorb and capture polysulfides and has a highly conductive C/N skeleton to achieve rapid electron migration. Moreover, the metallic Cu can react with polysulfides to further immobilize polysulfides. Thus, the Li-S batteries, with the aid of optimal Cu/mTiO2-NC, exhibit a desirable discharge capacity of 811 mA h g–1 after 100 cycles at 0.2 C, which is 50 % higher than that without Cu/mTiO2-NC. Moreover, the optimum Li-S batteries deliver a discharge capacity of 435.45 mA h g–1 after 600 cycles at 0.5 C, corresponding to attenuation per cycle of only 0.09 %.

Nitrogen doped multistage porous carbon for enhancing the adsorption-catalytic conversion of polysulfides in Li–S batteries

Lithium-sulfur (Li–S) batteries are regarded as promising next-generation electrochemical energy-storage devices owing to their high theoretical capacity of 1672 mAh/g for sulfur and high energy density of 2600 Wh kg−1. However, severe active sulfur losing and capacity fading originated from “shuttle effect” restrict their practical applications. Herein, nitrogen doped multistage porous carbon (denoted as MPC) was prepared as a novel sulfur host for Li–S batteries. Our strategies for the shuttle effect inhibition consist of three parts as described below, including accelerating conversion of lithium polysulfides by N-doping, blocking the shuttle channels by MPC, and enhancing adsorbability from MPC to lithium polysulfides. Expectantly, the Li–S batteries with the MPC@S cathode show high specific capacity of 508 mAh/g after 505 cycles when the sulfur loading is as high as 3.80 mg cm−2.

Porous N-Doped Carbon Decorated with Atomically Dispersed Independent Dual Metal Sites from Energetic Zeolite Imidazolate Frameworks as Bidirectional Catalysts for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have ultrahigh theoretical specific capacity and energy density, which are considered to be very promising energy storage devices. However, the slow redox kinetics of polysulfides are the main reason for the rapid capacity decay of Li-S batteries. A reasonable electrocatalyst for the Li-S battery should reduce the reaction barrier and accelerate the reaction kinetics of the bidirectional catalytic conversion of lithium polysulfides (LiPSs), thereby reducing the cumulative concentration of LiPSs in the electrolyte. In this report, porous N-doped carbon nanofibers decorated with independent dual metal sites as catalysts for Li-S batteries were fabricated in one step using a fusion-foaming method. Experimental and theoretical analyses demonstrate that the synergistic effect of independent dual metal sites provides strong LiPS affinity, improved electronic conductivity, and enhanced redox kinetics of polysulfides. Therefore, the assembled Li-S battery exhibits high rate performance (discharge specific capacity of 771 mA h g-1 at 2C) and excellent cycle stability (capacity decay rate of 0.51% after 1000 cycles at 1C).

Screening Graphene Supported Nitrogen-Coordinated Single-Atom Catalysts for Lithium Polysulfide Conversion in Lithium–Sulfur Batteries

Screening Graphene Supported Nitrogen-Coordinated Single-Atom Catalysts for Lithium Polysulfide Conversion in Lithium–Sulfur Batteries

Pyridyl Porphyrin as Electrocatalyst: Regulating the Redox Conversion of Lithium Polysulfides under Voltage

AbstractThe binding correlation between electrocatalyst and lithium polysulfides (LiPSs) determines the regulation of LiPSs’ redox conversion. However, how the correlation works on the LiPSs under voltage remains obscured. In this paper, the π‐conjugated aromatic pyridyl porphyrin with nitrogen of a lone pair of electrons is introduced as electrocatalyst to accelerate redox kinetics and inhibit polysulfides shuttle. On the foundation of DFT calculation and experimental tests, it is stated that the chemical binding between pyridyl porphyrin and lithium polysulfides is beefed up under higher voltage, which facilitates the charge transfer. Moreover, the molecular dynamics (MD) simulation of the solid‐liquid model shows that the presence of pyridyl porphyrin increases the binding chances between Li+ and S62− and forms clusters rather than dissolving in electrolyte, which is good for charge transfer and polysulfides localization. By hybridizing the pyridyl porphyrin with conductive cathode matrix of carbon nanotube and graphene oxide, the as‐fabricated Li2S‐T4PP‐GO‐CNT cathode delivers a high initial discharge capacity of 996.4 mAh g−1 at 0.1 C. The as‐made batteries with good electrochemical performance therefore show potential for trouble‐shooting and commercial utilization of lithium‐sulfur batteries (LSBs) in the future.

Synergistic Effect of Bimetallic MOF Modified Separator for Long Cycle Life Lithium‐Sulfur Batteries

AbstractSevere polysulfide dissolution and shuttling are the main challenges that plague the long cycle life and capacity retention of lithium‐sulfur (Li‐S) batteries. To address these challenges, efficient separators are designed and modified with a dual functional bimetallic metal‐organic framework (MOF). Flower‐shaped bimetallic MOFs (i.e., Fe‐ZIF‐8) with nanostructured pores are synthesized at 35 °C in water by introducing dopant metal sites (Fe), which are then coated on a polypropylene (PP) separator to provide selective channels, thereby effectively inhibiting the migration of lithium polysulfides while allowing homogeneous transport of Li‐ions. The active sites of the Fe‐ZIF‐8 enable electrocatalytic conversion, facilitating the conversion of lithium polysulfides. Moreover, the developed separator can prevent dendrite formation due to the uniform pore size and hence the even Li‐ion transport and deposition. A coin cell using a Fe‐ZIF‐8/PP separator with S‐loaded carbon cathode displayed a high cycle life of 1000 cycles with a high initial discharge capacity of 863 mAh g−1 at 0.5 C and a discharge capacity of 746 mAh g−1 at a high rate of 3 C. Promising specific capacity has been documented even under high sulfur loading of 5.0 mg cm−2 and electrolyte to the sulfur ratio (E/S) of 5 µL mg−1.

In situ self-assembled NiS2 nanoparticles on MXene nanosheets as multifunctional separators: Regulating shuttling effect and boosting redox reaction kinetics of lithium polysulfides

The notorious shuttling effect and sluggish redox kinetics towards lithium polysulfides (LiPSs) seriously hinder the practical application of lithium-sulfur (Li-S) batteries. The development of a multifunctional separator, as cooperator of trapper-catalyst-conductor, is deemed to be an efficient and feasible solving strategy. Herein, the NiS2/MXene nanocomposites with mesoporous structures were synthesized by the hydrothermal reaction, in which 0D ultrafine NiS2 nanoparticles were in situ self-assembled on 2D conductive MXene nanosheets. The NiS2/MXene nanocomposites were then modified on PP separators to form a thin layer of 8 μm in the Li-S batteries, which exhibit the significant characteristics of capture and conversion of LiPSs, as well as highly-efficient transferring pathways of electron/Li+ via the synergetic effect of NiS2 and MXene from their strong chemisorption abilities, rich catalyzing active sites, and high electron conductivity, accelerating to the redox reaction kinetics of LiPSs. Consequently, these Li-S batteries by using the modified PP separators show a high reversible capacity of 805.1 mAh/g at 0.2 C after 200 cycles. Even at 2 C, it still exhibits a low capacity decay of 0.038 % per cycle after long-term stable 1000 cycles. This work proves that the developing multifunctional separators are efficient strategies for high performance Li-S batteries.

Functional separator with 1 T/2H-MoSe2 nanosheets decorated nitrogen and sulfur co-doped mesoporous hollow carbon spheres for high-performance Li-S batteries

Due to the dissolution, shuttling, and tardy kinetics conversion of lithium polysulfides (LiPSs) during cycling, there are serious defects in the utilization of active material and capacity retention ability for lithium-sulfur batteries (LSBs). To inhibit effectively the shuttling effect of LiPSs, herein, we propose the dual design strategies, using 1 T/2H mixed phase MoSe2 (1 T/2H-MoSe2) nanosheets uniformly growing on the external surface and inner wall of nitrogen and sulfur co-doped mesoporous hollow carbon spheres (MoSe2-NSHC) as both sulfur host and modified material of conventional polypropylene (PP) separator. The hollow structure of MoSe2-NSHC has a large specific surface area and internal space, which not only loads a large amount of sulfur, but also buffers severe volume expansion of sulfur during charge/discharge process. Meanwhile, 1 T/2H-MoSe2 and co-doped nitrogen and sulfur in the carbon skeleton effectively anchor LiPSs and accelerate the kinetics conversion of LiPSs by forming chemical bond. Density-functional theory calculations indicate the corresponding mechanisms. Based on these advantages, lithium-sulfur battery assembled with a MoSe2-NSHC/S cathode and a MoSe2-NSHC-PP separator delivers an initial discharge capacity of 1402 mAh/g at 0.2C, and also exhibits the first discharge capacity of 1155 mAh/g at 0.5C with a capacity retention rate of 79 % after 100 cycles. And after 800 cycles at 1C, the outstanding long-term cyclability with a low capacity decay per cycle of 0.039 % is also obtained. Notably, even in case of sulfur loading of 3.2 mg cm−2 and electrolyte/sulfur ratio of 6 μL mg−1, lithium-sulfur battery still exhibits a good electrochemical performance. Importantly, this work provides a feasible approach for commercial application of LSBs.

Breaking Barriers to High-Practical Li-S Batteries with Isotropic Binary Sulfiphilic Electrocatalyst: Creating a Virtuous Cycle for Favorable Polysulfides Redox Environments.

Investigations into lithium-sulfur batteries (LSBs) has focused primarily on the initial conversion of lithium polysulfides (LiPSs) to Li2 S2 . However, the subsequent solid-solid reaction from Li2 S2 to Li2 S and the Li2 S decomposition process should be equally prioritized. Creating a virtuous cycle by balancing all three chemical reaction processes is crucial for realizing practical LSBs. Herein, amorphous Ni3 B in synergy with carbon nanotubes (aNi3 B@CNTs) is proposed to implement the consecutive catalysis of S8(solid) → LiPSs(liquid) → Li2 S(solid) →LiPSs(liquid) . Systematic theoretical simulations and experimental analyses reveal that aNi3 B@CNTs with an isotropic structure and abundant active sites can ensure rapid LiPSs adsorption-catalysis as well as uniform Li2 S precipitation. The uniform Li2 S deposition in synergy with catalysis of aNi3 B enables instant/complete oxidation of Li2 S to LiPSs. The produced LiPSs are again rapidly and uniformly adsorbed for the next sulfur evolution process, thus creating a virtuous cycle for sulfur species conversion. Accordingly, the aNi3 B@CNTs-based cell presents remarkable rate capability, long-term cycle life, and superior cyclic stability, even under high sulfur loading and extreme temperature environments. This study proposes the significance of creating a virtuous cycle for sulfur species conversion to realize practical LSBs.