Capacity Decay Rate Research Articles

Polymer Coating with Balanced Coordination Strength and Ion Conductivity for Dendrite-Free Zinc Anode.

Decorating Zn anodes with functionalized polymers is considered as an effective strategy to inhibit dendrite growth. However, this normally brings extra interfacial resistance rendering slow reaction kinetics of Zn2+ . Herein, a poly(2-vinylpyridine) (P2VP) coating with modulated coordination strength and ion conductivity for dendrite-free Zn anode is reported. The P2VP coating favors a high electrolyte wettability and rapid Zn2+ migration speed (Zn2+ transfer number, tZn 2+ = 0.58). Electrostatic potential calculation shows that P2VP mildly coordinates with Zn2+ (adsorption energy = -0.94eV), which promotes a preferential deposition of Zn along the (002) crystal plane. Notably, the use of partially (26%) quaternized P2VP (q-P2VP) further reduces the interfacial resistance to 126 Ω, leading to a high ion migration speed (tZn 2+ = 0.78) and a considerably low nucleation overpotential (18mV). As a result of the synergistic effect of mild coordination and partial electrolysis, the overpotential of the q-P2VP-decorated Zn anode retains at a considerably low level (≈46mV) over 1000h at a high current density of 10mA cm-2 . The assembled (NH4 )2 V6 O16 ·1.5H2 O || glass fiber || q-P2VP-Zn full cell reveals a lower average capacity decay rate of only 0.018% per cycle within 500 cycles at 1 A g-1 .

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).

Fe3O4/FeP hetero-hybrids confer polypropylene separator robust inhibitory effect to the shuttle of soluble lithium polysulfides

High energy density (2600 Wh kg−1) and low price of sulfur make lithium-sulfur batteries (LSBs) become one of the most promising cost-effective energy storage systems in the future. However, lithium-sulfur batteries are still subject to the shuttle effect of soluble lithium polysulfides (LPSs). Herein, ferroferric oxide/iron phosphide (Fe3O4/FeP) hetero-hybrids have been developed and applied as a functional layer to modify the polypropylene separator to inhibit the shuttle of soluble LPSs. Meanwhile, Fe3O4/FeP layer can also accelerate the conversion of adsorbed soluble LPSs due to excellent catalytic performance. As a result, LSBs using Fe3O4/FeP-modified PP separators exhibit superior cycling stability and rate performance. At 0.1C and 5C, it can deliver 1399.8 and 382.1 mAh g − 1, respectively. At 2C, its average capacity decay rate is only 0.0093 % during the initial 900 cycles. Together with the desirable mechanical properties, the Fe3O4/FeP-modified PP separator demonstrate a great potential for practical application in LSBs.

Suppressing shuttle effect of polysulfides by yttrium hydroxide nanoarchitecture for stable lithium‑sulfur batteries

Rechargeable lithium–sulfur (Li–S) batteries reveal promising prospect as high energy storage systems because of the extraordinary theoretical specific energy density. However, the shuttle effect and sluggish reaction kinetics of polysulfides hamper the commercialization applications of high energy density Li-S batteries. Herein, a novel and efficient sulfur host material of yttrium hydroxide (Y(OH)3) has rationally been achieved for Li–S batteries. Y(OH)3 host not only suppress shuttle effect of polysulfides by physical confinement and chemisorption, but also decline Li2S nucleation and deposition reaction barriers and expedite chemical reaction kinetics. Consequently, the prepared Y(OH)3/S cathodes achieve a high initial specific capacity of 1295 mAh g−1 at 0.1 C and improved cycling stability with a low capacity decay rate of 0.019% per cycle over 1000 cycles at 2.0 C. The enhanced performances confirm a potential host material for facilitating practical implementation of Li–S batteries.

Combining Janus Separator and Organic Cathode for Dendrite‐Free and High‐Performance Na‐Organic Batteries

AbstractThe growth of Na‐dendrites and the dissolution of organic cathodes are two major challenges that hinder the development of sodium‐organic batteries (SOBs). Herein, a multifunctional Janus separator (h‐BN@PP@C) by using an interfacial engineering strategy, is proposed to tackle the issues of SOBs. The carbon layer facing the organic cathode serves as a barrier to capture dissolved organic materials and enhance their utilization. Meanwhile, the h‐BN layer facing the Na anode possesses high thermal conductivity and mechanical strength, which mitigates the occurrence of localized‐temperature “hot spots” and promotes the formation of a NaF‐enriched SEI, thereby suppressing dendrite growth. Consequently, the Janus separator enables a stable Na plating/stripping cycling for 1000 h at 3 mA cm−2. Equipped with the Janus separator, organic cathodes including dibenzo[b,i]thianthrene‐5,7,12,14‐tetraone (DTT), pentacene‐5,7,12,14‐tetrone and Calix[4]quinone cathodes demonstrate high capacity and remarkable cycling performance. In particular, the DTT exhibits a bipolar co‐reaction storage mechanism and achieves an ultrahigh capacity (≈342.6 mAh g−1), long‐term cycling stability (capacity decay rate of 0.15% per cycle over 550 cycles at 500 mA g−1) and fast kinetics (1000 mA g−1≈2.8 C). This study offers a straightforward, effective, and promising solution to address the challenges in SOBs.

Preparation of LDHs-derived Co-Ni3N heterostructure modified porous carbon nanofibers as advanced interlayers for lithium-sulfur batteries

There are shuttle effects and slow kinetic transformation processes of polysulfides that must be overcome to attain excellent lithium-sulfur batteries (LSBs). Recently, developing catalysts to facilitate lithium polysulfides (LiPSs) conversion has attracted a large amount of attention. In this paper, a novel layered double hydroxides-derived (LDHs-derived) Co-Ni3N heterostructure anchored on nitrogen-doped carbon nanofibers (CNFs) is developed. The Co-Ni3N heterostructure with high catalytic activity and strong adsorption is capable of adsorbing long-chain polysulfides and significantly promotes LiPSs redox kinetics. Moreover, the Co-Ni3N-CNFs (450 °C/2 h) interlayer with hemp rope-like network structure accelerates the Li2S nucleation and provides high-conductivity channels. LSBs with the Co-Ni3N-CNFs (450 °C/2 h) interlayer exhibit remarkable initial discharge specific capacity (1359.9 mAh g−1 at 0.1C), exceptional rate performance (775.2 mAh g−1 at 2C), impressive cycling stability (with a capacity decay rate of 0.042 % over 1000 cycles at 2C), and high Coulombic efficiency (CE exceeding 99.5 %).

Polyaniline-coated S/Super-P composites as cathode materials for high performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries are promising alternatives to conventional lithium-ion batteries owing to their high theoretical capacity and eco-friendliness. However, their commercialization has been limited due to poor cathode conductivity and polysulfide dissolution. In this study, we synthesized a S/Super-P @ Polyaniline (S/Super-P @ PANi) composite via a straightforward high-energy ball milling (HEBM) and in-situ oxidative polymerization process. The refined sulfur and Super-P particles were encapsulated by a conductive PANi coating shell, which not only facilitated electron transfer but also inhibited the dissolution of lithium polysulfides through physical confinement and chemical adsorption. The S/Super-P @ PANi electrode showed a high initial capacity of 1185.3 mAh·g−1 at 0.1 C. Under a sulfur loading of 3.5 mg·cm−2, the electrode delivered an areal capacity of 2.8 mAh cm−2 and maintained 1.8 mAh cm−2 after 400 cycles, with a capacity decay rate of 0.08% at 0.5 C. This rational and scalable synthesis method has great potential for use in high-performance Li-S batteries.

In-situ coupling construction of interface bridge to enhance electrochemical stability of all solid-state lithium metal batteries

Polymer-based composite electrolytes composed of three-dimensional Li6.4La3Zr2Al0.2O12 (3D-LLZAO) have attracted increasing attention due to their continuous ion conduction and satisfactory mechanical properties. However, the organic/inorganic interface is incompatible, resulting in slow lithium-ion transport at the interface. Therefore, the compatibility of organic/inorganic interface is an urgent problem to be solved. Inspired by the concept of “gecko eaves”, polymer-based composite solid electrolytes with dense interface structures were designed. The bridging of organic/inorganic interfaces was established by introducing silane coupling agent (3-chloropropyl)trimethoxysilane (CTMS) into the PEO-3D-LLZAO (PL) electrolyte. The in-situ coupling reaction improves the interface affinity, strengthens the organic/inorganic interaction, reduces the interface resistance, and thus achieves an efficient interface ion transport network. The prepared PEO-3D-LLZAO-CTMS (PLC) electrolyte exhibits enhanced ionic conductivity of 6.04 × 10−4 S cm−1 and high ion migration number (0.61) at 60 °C and broadens the electrochemical window (5.1 V). At the same time, the PLC electrolyte has good thermal stability and high mechanical properties. Moreover, the LiFePO4|PLC|Li battery has excellent rate performance and cycling stability with a capacity decay rate of 2.2% after 100 cycles at 60 °C and 0.1 C. These advantages of PLC membranes indicate that this design approach is indeed practical, and the in-situ coupling method provides a new approach to address interface compatibility issues.

In-situ construction of a hybrid interfacial protective layer for highly stable Li metal anodes

Lithium (Li) metal is an ideal anode candidate for rechargeable batteries because of its ultra-high theoretical specific capacity. Unfortunately, the practical application of Li metal anodes (LMA) is severely limited by the uncontrollable formation and growth of dendrites and volume expansion. Thus, a protective layer is essential for stable and high-performance LMA. In this work, an organic-inorganic hybrid protective layer is in-situ prepared on Li foil surface (pa-Li), consisting of the organic Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP) and inorganic Ag-LixAgy composites. Going beyond conventional protective layers, the hybrid protective layer is flexible and enables strong interfacial adherence due to an alloying process. Furthermore, owing to the protective layer's outstanding lithiophilicity and mechanical stability, the pa-Li││pa-Li symmetric cell exhibits satisfactory stability for 1000 h at 5 mA/cm2, 5 mA h/cm2 with a low voltage hysteresis of ∼70 mV, while the full cell with a LiFePO4 cathode delivers an excellent reversible capacity of 128.9 mA h/g for 900 cycles at 2C with a capacity decay rate of 0.009 % per cycle.

Rational design of MoSSe nanosheets on N-doped carbon hollow spheres for accelerating polysulfide redox kinetics of high-performance lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries with high theoretical energy densities offer a promising alternative for next-generation energy storage. However, the poor conductivity, shuttle effect of lithium polysulfides (LiPSs), and large volume expansion upon cycling hinder their application. Hollow nanostructures can play an important role in achieving high sulfur loading, buffering volume expansion, and inhibiting LiPSs shuttling. In this work, MoSSe nanosheets grown on N-doped carbon hollow spheres (MoSSe/NC) are used as both sulfur host and separator to achieve catalytic adsorption and conversion of LiPSs. As a sulfur host, MoSSe/NC can enhance electron/ion transport and alleviate the volume expansion of sulfur during cycling, further accelerating the redox kinetics. The MoSSe/NC-modified separator can also induce interfacial charge modulation and expose more active sites, promoting rapid anchoring and conversion of LiPSs and uniform deposition of Li2S. Theoretical calculations and experiments verify that MoSSe/NC can catalyze the conversion of LiPSs, inhibit the shuttle effect, and effectively improve the electrochemical properties of sulfur. Therefore, the MoSSe/NC based Li-S battery exhibits high initial capacity (1455 mAh g−1), excellent rate performance (891 mAh g−1 at 2 C), and good cycling stability (0.049% capacity decay rate at 800 cycles at 1 C).

Hierarchical porous honeycomb microspheres assembled by MoS2 nanocrystals-embedded carbon nanosheets for high-performance lithium storage

Hierarchical porous honeycomb microspheres assembled by MoS2 nanocrystals-embedded carbon nanosheets are synthesized by constructing polystyrene (PS) sphere-embedded Mo-polydopamine organic/inorganic hybrid microspheres, followed by carbonization and sulfuration. The as-prepared composite is systematically studied by various material characterization techniques. It is found that the diameters of the microspheres and honeycomb pores are 3–5 μm and 200 nm. The specific surface area reaches 150.8 m2 g−1. MoS2@honeycomb carbon microsphere anode can achieve outstanding rate performance (237 mAh g−1 at 10 A g−1), high specific capacity and stable long-term cycling performance (reversible capacity of 1199 mAh g−1 at 0.1 A g−1 after 120 cycles, 599 mAh g−1 at 2 A g−1 after 300 cycles with capacity decay rate of 0.07 % per cycle, 495 mAh g−1 at 5 A g−1 after 500 cycles). The high reversible capacity is mainly derived from conversion reaction of MoS2 and lithiation reaction of S, as revealed by the analyses on the rate discharge curves. Kinetic measurements and ex-situ characterization further demonstrate the fast and stable Li+ diffusion, low impedance, strong capacitive effect and robust composite structure. The assembled full cell exhibits a reversible capacity of 209.7 mAh g−1 after 1880 cycles at 5 A g−1 and can power a red LED lamp. Overall, the excellent lithium storage performance manifests the significant potential of this MoS2 composite in high-performance lithium-ion batteries.

An all-biomaterials-based aqueous binder based on adsorption redox-mediated synergism for advanced lithium–sulfur batteries

The complex multistep electrochemical reactions of lithium polysulfides and the solid–liquid–solid phase transformation involved in the S8 to Li2S reactions lead to slow redox kinetics in lithium–sulfur batteries (Li–S batteries). However, some targeted researches have proposed strategies requiring the introduction of significant additional inactive components, which can seriously affect the energy density. Whereas polymer binders, proven to be effective in suppressing shuttle effects and constraining electrode volume expansion, also have promising potential in enhancing Li–S batteries redox kinetics. Herein, a novel aqueous polymer binder is prepared by convenient amidation reaction of fully biomaterials, utilizing its inherent rich amide groups for chemisorption and redox mediating ability of thiol groups to achieve adsorption redox-mediated synergism for efficient conversion of polysulfides. Li–S batteries based on N-Acetyl-L-Cysteine-Chitosan (NACCTS) binder exhibit high initial discharge specific capacity (1260.1 ​mAh ​g−1 at 0.2 ​C) and excellent cycling performance over 400 cycles (capacity decay rate of 0.018% per cycle). In addition, the batteries exhibit great areal capacity and stable capacity retention of 83.6% over 80 cycles even under high sulfur loading of 8.4 ​mg ​cm−2. This work offers a novel perspective on the redox-mediated functional design and provides an environmentally friendly biomaterials-based aqueous binder for practical Li–S battery.

VSe2/V2C heterocatalyst with built-in electric field for efficient lithium-sulfur batteries: Remedies polysulfide shuttle and conversion kinetics

Lithium sulfur (Li-S) battery is a kind of burgeoning energy storage system with high energy density. However, the electrolyte-soluble intermediate lithium polysulfides (LiPSs) undergo notorious shuttle effect, which seriously hinders the commercialization of Li-S batteries. Herein, a unique VSe2/V2C heterostructure with local built-in electric field was rationally engineered from V2C parent via a facile thermal selenization process. It exquisitely synergizes the strong affinity of V2C with the effective electrocatalytic activity of VSe2. More importantly, the local built-in electric field at the heterointerface can sufficiently promote the electron/ion transport ability and eventually boost the conversion kinetics of sulfur species. The Li-S battery equipped with VSe2/V2C-CNTs-PP separator achieved an outstanding initial specific capacity of 1439.1 mA h g−1 with a high capacity retention of 73% after 100 cycles at 0.1 C. More impressively, a wonderful capacity of 571.6 mA h g−1 was effectively maintained after 600 cycles at 2 C with a capacity decay rate of 0.07%. Even under a sulfur loading of 4.8 mg cm−2, areal capacity still can be up to 5.6 mA h cm−2. In-situ Raman tests explicitly illustrate the effectiveness of VSe2/V2C-CNTs modifier in restricting LiPSs shuttle. Combined with density functional theory calculations, the underlying mechanism of VSe2/V2C heterostructure for remedying LiPSs shuttling and conversion kinetics was deciphered. The strategy of constructing VSe2/V2C heterocatalyst in this work proposes a universal protocol to design metal selenide-based separator modifier for Li-S battery. Besides, it opens an efficient avenue for the separator engineering of Li-S batteries.

Dual-functional chloropyrazine additives for enhanced performance of lithium-sulfur batteries

The commercialization of lithium-sulfur batteries (LSBs) faces challenges due to uncontrolled lithium deposition and lithium polysulfides (LiPSs) shuttling. In this study, a class of chloropyrazine-based electrolyte additives was introduced to address these issues. The results showed that the presence of chloropyrazine facilitated the formation of a robust and smooth organic-inorganic hybrid solid-electrolyte interface (SEI) enriched with LiCl. This SEI layer enabled reversible lithium plating/stripping, suppressed dendrite growth, and protected the lithium anode from detrimental side reactions with LiPSs. Furthermore, Density functional theory (DFT) results demonstrate that chloropyrazine additives effectively modulated the molecular orbital energy levels of LiPSs and promoted the kinetics of their conversion reactions. LSBs incorporating chloropyrazine additives demonstrated outstanding high-rate performance and long-term cycling stability, with over 800 cycles at 1 C rate and a capacity retention of 81.6 %. Even under challenging conditions of high sulfur loading (5.8 mg cm−2) and low electrolyte-to-sulfur ratio (5 μL mg−1), the battery demonstrated capacity decay rate of only 0.066 % per cycle after 500 cycles at 0.2 C rate. With the highlights of dual-functional chloropyrazine electrolyte additives in improving interfacial chemistry and modulating the orbital energy levels of LiPSs, this work offers a promising direction for advanced electrolyte design in LSBs.

Interfacial Manipulation via In Situ Constructed Fast Ion Transport Channels toward an Ultrahigh Rate and Practical Li Metal Anode.

The successful substitution of Li metal for the conventional intercalation anode can promote a significant increase in the cell energy density. However, the practical application of the Li metal anode has long been fettered by the unstable solid electrolyte interface (SEI) layer on the Li metal surface and notorious dendritic Li growth. Herein, a stabilized SEI layer with in situ constructed fast ion transport channels has successfully been achieved by a robust In2S3-cemented poly(vinyl alcohol) coating. The modified Li metal demonstrates significantly enhanced Coulombic efficiency, high rate performance (10 mA cm-2), and ultralong life cycling stability (∼4900 cycles). The Li|LiCoO2 (LCO) cell presents an ultralong-term stable operation over 500 cycles at 1 C with an extremely low capacity decay rate (∼0.018% per cycle). And the Li|LCO full cell with the ultrahigh loading cathode (∼25 mg cm-2) and ultrathin Li foil (∼40 μm) also reveals a prolonged cycling performance under the low negative-to-positive capacity ratio of 2.2. Furthermore, the Li|LCO pouch cell with a commercial cathode and ultrathin Li foil still manifests excellent cycling performance even under the harsh conditions of limited Li metal and lean electrolyte. This work provides a cost-effective and scalable strategy toward high performance practical Li metal batteries.

A Comparative Study of Nafion 212 and Sulfonated Poly(Ether Ether Ketone) Membranes with Different Degrees of Sulfonation on the Performance of Iron-Chromium Redox Flow Battery.

For an iron-chromium redox flow battery (ICRFB), sulfonated poly(ether ether ketone) (SPEEK) membranes with five various degrees of sulfonation (DSs) are studied. To select the SPEEK membrane with the ideal DS for ICRFB applications, the physicochemical characteristics and single-cell performance are taken into consideration. Following all the investigations, it has been determined that the SPEEK membrane, which has a DS of 57% and a thin thickness of 25 μm, is the best option for replacing commercial Nafion 212 in ICRFB. Firstly, it exhibits a better cell performance according to energy efficiency (EE) and coulombic efficiency (CE) at the current density range between 40 mA cm-2 and 80 mA cm-2. Additionally, it has a more stable EE (79.25-81.64%) and lower discharge capacity decay rate (50%) than the Nafion 212 (EE: 76.74-81.45%, discharge capacity decay: 76%) after 50 charge-discharge cycles, which proves its better oxidation stability as well. In addition, the longer self-discharge time during the open-circuit voltage test further demonstrates that this SPEEK membrane could be employed for large-scale ICRFB applications.

Lithiophilic metal oxide-based double gradient anode host design for lithium-sulfur batteries

The development of rechargeable lithium-sulfur (Li-S) batteries is hampered by Li dendrite growth and large volume changes in the anode. To tackle these issues, a novel double gradient anode host material consists of carbon nanofibers (CNFs) embedded ZnO and Co3O4 is developed. In this ZnOCo3O4/CNF composite, the decorated ZnO and Co3O4 forms lithiophilic and Li nucleation overpotential double gradient, which is beneficial for the uniform Li deposition and suppressing the irregular growth of Li dendrites. The 3D network structure of the CNFs substrate improves the electrical conductivity and buffering the stress of volume changes as well. Owing to these features, the ZnOCo3O4/CNF electrode exhibits stable voltage during the 400 h plating/stripping process at current density of 5 mA cm−2 and delivers an area capacity of 5 mAh cm−2. The Li@ZnOCo3O4/CNF||S/CNT battery maintains excellent stability with capacity decay rate of 0.036 % per cycle after 500 cycles at 1 C. The design of gradient anode hosts constructed from bimetallic oxides offers a promising alternative strategy for suppressing the irregular growth of Li dendrites, thereby increasing the cycle life of the batteries.

Rational Design of Hollow Structural Materials for Sodium-Ion Battery Anodes.

The development of sodium-ion battery (SIB) anodes is still hindered by their rapid capacity decay and poor rate capabilities. Although there have been some new materials that can be used to fabricate stable anodes, SIBs are still far from wide applications. Strategies like nanostructure construction and material modification have been used to prepare more robust SIB anodes. Among all the design strategies, the hollow structure design is a promising method in the development of advanced anode materials. In the past decade, research efforts have been devoted to modifying the synthetic route, the type of templates, and the interior structure of hollow structures with high capacity and stability. A brief introduction is made to the main material systems and classifications of hollow structural materials first. Then different morphologies of hollow structural materials for SIB anodes from the latest reports are discussed, including nanoboxes, nanospheres, yolk shells, nanotubes, and other more complex shapes. The most used templates for the synthesis of hollow structrual materials are covered and the perspectives are highlighted at the end. This review offers a comprehensive discussion of the synthesis of hollow structural materials for SIB anodes, which could be potentially of use to research areas involving hollow materials design for batteries.

Mott Schottky heterojunction Co/CoSe2 electrocatalyst: Achieved rapid conversion of polysulfides and Li2S deposition dissolution via built-in electric field interface effect

Rechargeable lithium-sulfur (Li-S) batteries are considered ideal candidates for the next generation of energy storage devices. However, the insulation properties of S and Li2S, as well as the notorious “shuttle effect” of lithium polysulfide, result in severe loss of active sulfur, poor redox kinetics, and rapid capacity decline. To overcome these limitations, this paper designs a self-supporting electrocatalytic electrode based on Co/CoSe2 Mott Schottky heterojunction coated carbon nanofibers (Co/CoSe2@NCNFs), and engineers it for capturing and converting polysulfides. Density functional theory calculations show that the introduction of Co/CoSe2 heterojunction effectively reduces the redox barrier of Li2S. The electron current and electron interaction at the Co/CoSe2 interface induce the redistribution of charge density in the depletion region, thus increasing the chemical reactivity of the metal semiconductor heterojunction interface, which is conducive to the ion/electron transport, polysulfide conversion and Li2S oxidation process. Therefore, the Li-S battery assembled by Co/CoSe2@NCNFs/S electrode exhibited a high initial specific capacity of 1043.3 mAh/g at 1C, and maintained a capacity of 709.9 mAh/g after 1000 cycles, with a capacity decay rate of only 0.032% per cycle. The proposed Mott Schottky heterojunction as an electrocatalyst deepens the promotion of polysulfides and Li2S in long-life Li-S batteries.

Constructing MoS2-SnS heterostructures on N-doped carbon nanosheets for enhanced catalytic conversion of polysulfides in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have been regarded as potential candidates for next-generation high-performance energy storage systems due to the rich sulfur reserves, nontoxicity, high theoretical capacity, and energy density. However, the Li-S batteries suffer from the slow reaction kinetics and lithium polysulfide (LiPSs) shuttling. To address these issues, a bimetallic sulfide MoS2-SnS heterostructure has been constructed by a salt-template method to modify the separator of Li-S batteries. The 3D porous MoS2-SnS heterostructure on N-doped carbon (MoS2-SnS/NC) can improve the LiPSs adsorption and accelerate the LiPSs conversion and Li2S uniform nucleation/deposition due to its pore structure, polar bond, and built-in electric field at the interface of MoS2 and SnS. Therefore, the prepared MoS2-SnS/NC-PP heterostructure exhibits a high initial capacity (1504.6 mAh g-1), superior rate performance (690.1 mAh g-1 at 4C), and good cycling stability (0.07 % capacity decay rate at 400 cycles at 4C). When the sulfur loading is 3.50 mg cm−2, the Li-S battery delivers a capacity of 635 mAh g-1.