Highly Crystalline Layered VS2 Nanosheets for All-Solid-State Lithium Batteries with Enhanced Electrochemical Performances

"Fast-Charging" Anode Materials for Lithium-Ion Batteries from Perspective of Ion Diffusion in Crystal Structure

"Fast-charging" lithium-ion batteries have gained a multitude of attention in recent years since they could be applied to energy storage areas like electric vehicles, grids, and subsea operations. Unfortunately, the excellent energy density could fail to sustain optimally while lithium-ion batteries are exposed to fast-charging conditions. In actuality, the crystal structure of electrode materials represents the critical factor for influencing the electrode performance. Accordingly, employing anode materials with low diffusion barrier could improve the "fast-charging" performance of the lithium-ion battery. In this Review, first, the "fast-charging" principle of lithium-ion battery and ion diffusion path in the crystal are briefly outlined. Next, the application prospects of "fast-charging" anode materials with various crystal structures are evaluated to search "fast-charging" anode materials with stable, safe, and long lifespan, solving the remaining challenges associated with high power and high safety. Finally, summarizing recent research advances for typical "fast-charging" anode materials, including preparation methods for advanced morphologies and the latest techniques for ameliorating performance. Furthermore, an outlook is given on the ongoing breakthroughs for "fast-charging" anode materials of lithium-ion batteries. Intercalated materials (niobium-based, carbon-based, titanium-based, vanadium-based) with favorable cycling stability are predominantly limited by undesired electronic conductivity and theoretical specific capacity. Accordingly, addressing the electrical conductivity of these materials constitutes an effective trend for realizing fast-charging. The conversion-type transition metal oxide and phosphorus-based materials with high theoretical specific capacity typically undergoes significant volume variation during charging and discharging. Consequently, alleviating the volume expansion could significantly fulfill the application of these materials in fast-charging batteries.

Heterostructure and doping dual strategies engineering of MoS1.5Se0.5@VS2 nanosheets aggregated nano-roses for super sodium-ion batteries

Herein, selenium (Se)-doped MoS_1.5Se_0.5@VS₂ nanosheets aggregated nano-roses were successfully prepared from a simple hydrothermal process and the subsequent selenium doping process. The hetero-interfaces between MoS_1.5Se_0.5 and VS₂ phase can effectively promote the charge transfer. Meanwhile, the different redox potentials of MoS_1.5Se_0.5 and VS₂ alleviate volume expansion during the repeated sodiation/desodiation processes, which improves the electrochemical reaction kinetics and structural stability of electrode material. Besides, Se doping can induce charge reconstruction and improve the conductivity of electrode materials, resulting in improved diffusion reaction kinetics by expanding interlayer spacing and exposing more active sites. When used as anode material for sodium ion batteries (SIBs), the MoS_1.5Se_0.5@VS₂ heterostructure exhibits excellent rate capability and long-term cycling stability with the capacity of 533.9 mAh g^-1 at 0.5 A g^-1 and a reversible capacity of 424.5 mAh g^-1 after 1000 cycles at 5 A g^-1, demonstrating potential application as anode material for SIBs.

Formation of Carbon-Incorporated NiO@Co3O4 Nanostructures via a Direct Calcination Method and Their Application as Battery-Type Electrodes for Hybrid Supercapacitors

Nickel and cobalt oxides are promising electrode materials for supercapacitors, but their poor conductivity and sluggish kinetics seriously hinder their application. Herein, a simple one-step calcination method was proposed to prepare carbon-incorporated NiO@Co₃O₄ (denoted as CNC) using a NiCo Prussian blue analogue (NiCo-PBA) as a precursor. The effect of calcination temperature on the electrochemical behavior of CNC was investigated. Benefiting from the relatively large specific surface area and porous structure characteristics, when used as an electrode for supercapacitors, the CNC obtained at 400 °C shows the typical features of a battery-type electrode, with a good specific capacitance of 208.5 F g^-1 at 1 A g^-1 and a rate capability of 70.8% at 30 A g^-1. The hybrid supercapacitor (HSC) constructed with the optimum CNC electrode can provide a high energy density of 32.6 Wh kg^-1 at the corresponding power density of 750.0 W kg^-1 and an excellent cycling stability of 87.1% over 5000 cycles. This study provides a simple calcination method for preparing MOF-derived high-conductivity mixed metal oxide electrode materials for supercapacitors.

A customized strategy to design intercalation-type Li-free cathodes for all-solid-state batteries

Pairing Li-free transition-metal-based cathodes (MX) with Li-metal anodes is an emerging trend to overcome the energy-density limitation of current rechargeable Li-ion technology. However, the development of practical Li-free MX cathodes is plagued by the existing notion of low voltage due to the long-term overlooked voltage-tuning/phase-stability competition. Here, we propose a p-type alloying strategy involving three voltage/phase-evolution stages, of which each of the varying trends are quantitated by two improved ligand-field descriptors to balance the above contradiction. Following this, an intercalation-type 2H-V_1.75Cr_0.25S₄ cathode tuned from layered MX₂ family is successfully designed, which possesses an energy density of 554.3 Wh kg^-1 at the electrode level accompanied by interfacial compatibility with sulfide solid-state electrolyte. The proposal of this class of materials is expected to break free from scarce or high-cost transition-metal (e.g. Co and Ni) reliance in current commercial cathodes. Our experiments further confirm the voltage and energy-density gains of 2H-V_1.75Cr_0.25S₄. This strategy is not limited to specific Li-free cathodes and offers a solution to achieve high voltage and phase stability simultaneously.

Computational screening of single-atom catalysts supported by VS2 monolayers for electrocatalytic oxygen reduction/evolution reactions

The development of highly efficient bifunctional electrocatalysts to boost oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly desirable for energy conversion and storage devices. Herein, by means of comprehensive first-principles computations, we systematically explored the catalytic activities of a series of single transition metal atoms anchored on two-dimensional VS₂ monolayers (TM@VS₂) for ORR/OER. Our results revealed that Ni@VS₂ exhibits low overpotentials for both ORR (0.45 V) and OER (0.31 V), suggesting its great potential as a bifunctional catalyst, which is mainly induced by its moderate interaction with oxygenated intermediates according to the established scaling relationship and volcano plot. Interestingly, the substituted doping of nitrogen heteroatoms into the VS₂ substrate can further effectively improve the ORR/OER activity of the active metal atom to achieve more eligible ORR/OER bifunctional catalysts. Our results not only propose a new class of potential bifunctional oxygen catalysts but also offer a feasible strategy for further tuning their catalytic activity.

2D Materials for All-Solid-State Lithium Batteries

Although one of the most mature battery technologies, lithium-ion batteries still have many aspects that have not reached the desired requirements, such as energy density, current density, safety, environmental compatibility, and price. To solve these problems, all-solid-state lithium batteries (ASSLB) based on lithium metal anodes with high energy density and safety have been proposed and become a research hotpot in recent years. Due to the advanced electrochemical properties of 2D materials (2DM), they have been applied to mitigate some of the current problems of ASSLBs, such as high interface impedance and low electrolyte ionic conductivity. In this work, the background and fabrication method of 2DMs are reviewed initially. The improvement strategies of 2DMs are categorized based on their application in the three main components of ASSLBs: The anode, cathode, and electrolyte. Finally, to elucidate the mechanisms of 2DMs in ASSLBs, the role of in situ characterization, synchrotron X-ray techniques, and other advanced characterization are discussed.

Recent advances of metal telluride anodes for high-performance lithium/sodium-ion batteries

Metal tellurides (MTs) have emerged as highly promising candidate anode materials for state-of-the-art lithium-ion batteries (LIBs) and sodium ion batteries (SIBs). This is owing to the unique crystal structure, high intrinsic conductivity, and high trap density of such materials. The present work delivers a detailed discussion on the latest research and progress associated with the use of MTs for LIBs/SIBs with a focus on reaction mechanisms, challenges, electrochemical performance, and synthesis strategies. Further, the prospects and future development of MT anode materials are discussed in terms of strategies to overcome the existing limitations. This review provides both an in-depth understanding of MTs and provides the driving force for expanding research on MTs for energy storage and conversion applications.

Low crystalline 1T-MoS2@S-doped carbon hollow spheres as an anode material for Lithium-ion battery

A low crystalline 1T-MoS₂@S-doped carbon (MoS₂@SC) composite was successfully synthesized via a facile hydrothermal process. The composite is comprised by few-layer 1T-MoS₂ nanosheets covered by an amorphous carbon layer with an expanded interlayer d-spacing of 1.01 nm. This structure is conducive to the fast transport of lithium-ions and volume accommodation during the charge-discharge process when the composite is applied as an anode material for LIBs. Additionally, the high conductivity and layered structure of 1T-MoS₂ also facilitate fast of ion/electron transport, contributing to the improvement of the electrochemical properties. Therefore, this material demonstrated a high rate performance and excellent cycling stability, with the capacities of 847 and 622 mA h g^-1 achieved at the current densities of 0.2 A g^-1 and 2 A g^-1, respectively. Even at a larger current density of 2 A g^-1, MoS₂@SC delivered a high reversible capacity of 659 mA h g^-1 with an average capacity loss of 0.006% per cycle after 500 cycles.

A Self-Healing Flexible Quasi-Solid Zinc-Ion Battery Using All-In-One Electrodes

Self-healing and flexibility are significant for many emerging applications of secondary batteries, which have attracted broad attention. Herein, a self-healing flexible quasi-solid Zn-ion battery composing of flexible all-in-one cathode (VS2 nanosheets growing on carbon cloth) and anode (electrochemically deposited Zn nanowires), and a self-healing hydrogel electrolyte, is presented. The free-standing all-in-one electrodes enable a high capacity and robust structure during flexible transformation of the battery, and the hydrogel electrolyte possesses a good self-healing performance. The presented battery remains as a high retention potential even after healing from being cut into six pieces. When bending at 60°, 90°, and 180°, the battery capacities remain 124, 125, and 114 mAh g-1, respectively, cycling at a current density of 50 mA g-1. Moreover, after cutting and healing twice, the battery still delivers a stable capacity, indicating a potential use of self-healing and wearable electronics.

Lithium/Sulfide All-Solid-State Batteries using Sulfide Electrolytes

All-solid-state lithium batteries (ASSLBs) are considered as the next generation electrochemical energy storage devices because of their high safety and energy density, simple packaging, and wide operable temperature range. The critical component in ASSLBs is the solid-state electrolyte. Among all solid-state electrolytes, the sulfide electrolytes have the highest ionic conductivity and favorable interface compatibility with sulfur-based cathodes. The ionic conductivity of sulfide electrolytes is comparable with or even higher than that of the commercial organic liquid electrolytes. However, several critical challenges for sulfide electrolytes still remain to be solved, including their narrow electrochemical stability window, the unstable interface between the electrolyte and the electrodes, as well as lithium dendrite formation in the electrolytes. Herein, the emerging sulfide electrolytes and preparation methods are reviewed. In particular, the required properties of the sulfide electrolytes, such as the electrochemical stabilities of the electrolytes and the compatible electrode/electrolyte interfaces are highlighted. The opportunities for sulfide-based ASSLBs are also discussed.

Boosting reaction kinetics and reversibility in Mott-Schottky VS2/MoS2 heterojunctions for enhanced lithium storage

Heterostructures have lately been recognized as a viable implement to achieve high-energy Li-ion batteries (LIBs) because the as-formed built-in electric field can greatly accelerate the charge transfer kinetics. Herein, we have constructed the Mott-Schottky heterostructured VS₂/MoS₂ hybrids with tailorable 1T/2H phase based on their matchable formation energy, which are made of metallic and few-layered VS₂ vertically grown on MoS₂ surface. The density functional theory (DFT) calculations unveil that such heterojunctions drive the rearrangement of energy band with a facilitated reaction kinetics and enhance the Li adsorption energy more than twice compared to the MoS₂ surface. Furthermore, the VS₂ catalytically expedites the Li-S bond fracture and meantime the enriched Mo⁶⁺ enables the sulfur anchoring toward the oriented reaction with Li⁺ to form Li₂S, synergistically enhancing the reversibility of electrochemical redox. Consequently, the as-obtained VS₂/MoS₂ hybrids deliver a very large specific capacity of 1273 mAh g^-1 at 0.1 A g^-1 with 61% retention even at 5 A g^-1. It can also stabilize 100 cycles at 0.5 A g^-1 and 500 cycles at 1 A g^-1. The findings provide in-depth insights into engineering heterojunctions towards the enhancement of reaction kinetics and reversibility for LIBs.

Direct Observation of Li Migration into V5S8: Order to Antisite Disorder Intercalation Followed by the Topotactic-Based Conversion Reaction

Two-dimensional transition-metal dichalcogenides hold great potential in rechargeable lithium-ion batteries. Their electrochemical properties are closely related to the structural evolutions during lithium-ion migration. Understanding these migration/reaction mechanisms is important to help improve battery performance. Herein, we report the real-time and atomic-scale observation of phase transitions during the lithiation and delithiation for V₅S₈ via in situ electron diffraction and high-resolution transmission electron microscopy techniques. We find that the phase transformation proceeds via a sequence of order to antisite disorder intercalation and topotactic-based conversion reaction. During the intercalation reaction, the lithium ion destroys the orderings of the interstitial V with the formation of Li/V antisite. Such a reaction is found to be reversible, i.e., the extraction of lithium from Li_xV₅S₈ leads to the recovery of V orderings. The conversion reaction involves heterogeneous nucleation of Li₂S with 3-20 nm nanodomains, which maintain the crystallographic integrity with Li_xV₅S₈. These findings elucidate the complex interactions between the lithium ion and host V₅S₈ during ionic migration in solids, which should be helpful in understanding the relationship between phase transformation kinetics and battery performance.

A 3D polyacrylonitrile nanofiber and flexible polydimethylsiloxane macromolecule combined all-solid-state composite electrolyte for efficient lithium metal batteries

All-solid-state polymer electrolytes have received widespread attention due to their superior safety over liquid electrolytes that are prone to leaks. However, poor ionic conductivity and uncontrollable lithium dendrite growth have greatly limited the rapid development of polymer electrolytes. Hence, we report a composite polymer electrolyte combining a polyacrylonitrile (PAN) electrospun fiber membrane, flexible polydimethylsiloxane (PDMS) macromolecules and a polyethylene oxide (PEO) polymer. The introduction of PDMS with a highly flexible molecular chain, ultra-low glass transition energy and high free volume can help optimize lithium ion migration paths and improve the interface compatibility between the electrolyte and the electrode. In addition, the nano-network structure of the PAN nanofiber membrane can promote the interaction between adjacent polymer molecular chains and improve the mechanical properties of the composite electrolyte to suppress the lithium dendrite growth. The synergistic effect of the PDMS and PAN electrospun nanofiber membranes endows the composite electrolyte with superior ionic conductivity and excellent electrochemical stability towards lithium metal. The interface impedance of the Li/Li symmetric battery with the composite electrolyte after 15 days of continuous standing has no significant change compared with the initial state, and the battery can maintain stable cycling for 1200 h without short circuit under a dynamic current of 0.3 mA cm-2. The obtained composite polymer electrolyte has potential application prospects in the field of high-energy lithium metal batteries.

Emerging Layered Metallic Vanadium Disulfide for Rechargeable Metal-Ion Batteries: Progress and Opportunities

Rechargeable metal-ion batteries (RMIBs), as one of the most viable technologies for electric vehicles (EVs) and large-scale energy storage (EES), have received extensive research attention for a long time. Electrode materials play a decisive role on capacity, energy, and power density, which directly affect the practical applications of RMIBs in EVs and EES. As an electrode material, layered metallic vanadium disulfide (VS₂ ) has theoretically and experimentally produced inspiring results because of its synthetic characteristics of continuously adjustable V valence, large interlayer spacing, weak interlayer interactions, and high surface activity. Herein, the synthetic strategies, theoretical metal-ion storage sites, diffusion kinetics, and experimental electrochemical reaction mechanisms of VS₂ for RMIBs are systematically introduced. Emphatically, the critical issues that affect the metal-ion storage properties of the VS₂ electrode and three major enhancement strategies, namely, optimizing the electrolyte and cutoff voltage, constructing a space-confined structure, and controlling the crystal structure are summarized, with the aim of promoting the development of transition-metal dichalcogenides. Finally, the challenges and opportunities for the future development of VS₂ in the energy-storage field are presented. It is hoped that this review can attract attention from researchers for investigations into emerging layered metallic VS₂ and provide insights toward the design of an excellent VS₂ electrode material for next-generation, high-performance RMIBs.

Rational Design of Nanoporous MoS2 /VS2 Heteroarchitecture for Ultrahigh Performance Ammonia Sensors

2D transition metal dichalcogenides (TMDs) have received widespread interest by virtue of their excellent electrical, optical, and electrochemical characteristics. Recent studies on TMDs have revealed their versatile utilization as electrocatalysts, supercapacitors, battery materials, and sensors, etc. In this study, MoS₂ nanosheets are successfully assembled on the porous VS₂ (P-VS₂ ) scaffold to form a MoS₂ /VS₂ heterostructure. Their gas-sensing features, such as sensitivity and selectivity, are investigated by using a quartz crystal microbalance (QCM) technique. The QCM results and density functional theory (DFT) calculations reveal the impressive affinity of the MoS₂ /VS₂ heterostructure sensor toward ammonia with a higher adsorption uptake than the pristine MoS₂ or P-VS₂ sensor. Furthermore, the adsorption kinetics of the MoS₂ /VS₂ heterostructure sensor toward ammonia follow the pseudo-first-order kinetics model. The excellent sensing features of the MoS₂ /VS₂ heterostructure render it attractive for high-performance ammonia sensors in diverse applications.

Poplar flower-like nitrogen-doped carbon nanotube@VS4 composites with excellent sodium storage performance

As a new anode material for sodium-ion batteries (SIBs), VS₄ shows impressive energy storage potential due to its unique one-dimensional parallel chain structure, large chain spacing and high sulfur content.

Constructing BaLi2Ti6O14@C nanofibers with a low carbon content as high-performance anode materials for Li-ion batteries

In this work, BaLi₂Ti₆O₁₄ nanofibers coated by a thin carbon layer were rationally designed and synthesized by a controlled electrospinning process and a simple annealing process.

Hierarchical Composite of Rose-Like VS2 @S/N-Doped Carbon with Expanded (001) Planes for Superior Li-Ion Storage

In the present work, a hierarchical composite of rose-like VS₂ @S/N-doped carbon (VS₂ @SNC) with expanded (001) planes is successfully fabricated through a facile synthetic route. Notably, the d-spacing of (001) planes is expanded to 0.92 nm, which is proved to dramatically reduce the energy barrier for Li⁺ diffusion in the composite of VS₂ @SNC by density functional theory calculation. On the other hand, the S/N-doped carbon in the composite greatly promotes the electrical conductivity and enhances the structural stability. In addition, the hierarchical structure of VS₂ @SNC facilitates rapid electrolyte diffusion and increases the contact area between the electrode and electrolyte simultaneously. Benefiting from the merits mentioned above, the VS₂ @SNC electrode exhibits excellent electrochemical properties, such as a large reversible capacity of 971.6 mA h g^-1 at 0.2 A g^-1 , an extremely high rate capability of 772.1 mA h g^-1 at 10 A g^-1 , and a remarkable cycling stability up to 600 cycles at 8 A g^-1 with a capacity of 684.5 mA h g^-1 , making it a promising candidate as an anode material for lithium-ion batteries.

Building Better Batteries in the Solid State: A Review

Most of the current commercialized lithium batteries employ liquid electrolytes, despite their vulnerability to battery fire hazards, because they avoid the formation of dendrites on the anode side, which is commonly encountered in solid-state batteries. In a review two years ago, we focused on the challenges and issues facing lithium metal for solid-state rechargeable batteries, pointed to the progress made in addressing this drawback, and concluded that a situation could be envisioned where solid-state batteries would again win over liquid batteries for different applications in the near future. However, an additional drawback of solid-state batteries is the lower ionic conductivity of the electrolyte. Therefore, extensive research efforts have been invested in the last few years to overcome this problem, the reward of which has been significant progress. It is the purpose of this review to report these recent works and the state of the art on solid electrolytes. In addition to solid electrolytes stricto sensu, there are other electrolytes that are mainly solids, but with some added liquid. In some cases, the amount of liquid added is only on the microliter scale; the addition of liquid is aimed at only improving the contact between a solid-state electrolyte and an electrode, for instance. In some other cases, the amount of liquid is larger, as in the case of gel polymers. It is also an acceptable solution if the amount of liquid is small enough to maintain the safety of the cell; such cases are also considered in this review. Different chemistries are examined, including not only Li-air, Li-O2, and Li-S, but also sodium-ion batteries, which are also subject to intensive research. The challenges toward commercialization are also considered.

High Capacity and Superior Cyclic Performances of All-Solid-State Lithium-Sulfur Batteries Enabled by a High-Conductivity Li10SnP2S12 Solid Electrolyte

All-solid-state lithium-sulfur batteries (ASSLSBs) employing sulfide-based solid electrolytes have gained widespread attention for their high energy density and intrinsic safety. Li₁₀SnP₂S₁₂ is identified as one of the most rivaling candidates in sulfide electrolytes. Herein, a highly Li-ion-conductive Li₁₀SnP₂S₁₂ solid-state electrolyte (SSE) is synthesized via a combination of high-energy ball-milling and heat treatment processes, which is more facile and efficient compared with other previously reported methods. The obtained Li₁₀SnP₂S₁₂ SSE exhibits high ionic conductivity (3.2 × 10^-3 S cm^-1) at room temperature (RT). The effects of the annealing temperature on the Li-ion conductivity and activation energy of Li₁₀SnP₂S₁₂ are also thoroughly studied. Moreover, the ASSLSBs based on the Li₁₀SnP₂S₁₂ electrolyte are constructed, and they deliver a high initial capacity of 1601.7 mAh g^-1 at 40 mA g^-1. A favorable capacity retention upon cycling and a good rate performance are also achieved at RT. Concomitantly, the Coulombic efficiency approaches 100% during the prolonged cycling. This work tremendously accelerates the practical applications of the Li₁₀SnP₂S₁₂ SSE among the emerging high-energy ASSLSBs.

Effective Strategy for Enhancing the Performance of Li4Ti5O12 Anodes in Lithium-Ion Batteries: Magnetron Sputtering Molybdenum Disulfide-Optimized Interface Architecture

The interface between the current collector and active material is the primary interface of charge transfer. Herein, we designed an effective strategy to optimize the interface architecture by depositing molybdenum disulfide on the copper foil surface (Cu-MoS₂) via magnetron sputtering. The Cu-MoS₂ is directly used as a current collector and supports the Li₄Ti₅O₁₂ anode (Cu-MoS₂-LTO). Typically, after being cycled at 1 A g^-1 for 300 cycles, the capacities of the Cu-LTO cell and Cu-MoS₂ cell are about 114.94 and 128.35 mA h g^-1, respectively, whereas the capacity of the Cu-MoS₂-LTO cell is as high as 373.9 mA h g^-1 with a capacity retention rate of 89.1%. The MoS₂ not only optimizes the interfacial architecture but also provides an additional capacity contribution to the Cu-MoS₂-LTO cell. Based on scanning electron microscopy and X-ray photoelectron spectroscopy test analysis, we propose a dual interface model. It is revealed that the molybdenum disulfide film can significantly improve the charge-transfer efficiency and uniformity of the interface, reduce internal resistance of the batteries, prevent oxidation of the copper foil, and thereby improve the chemical stability of the current collector. In addition, magnetron sputtering technology has large-scale productivity and greatly enhances the industrial application of this strategy.

Design and understanding of core/branch-structured VS2 nanosheets@CNTs as high-performance anode materials for lithium-ion batteries

Revealing the electrochemical property-structure relationship and observing the dynamic structural evolution of electrode materials are critically important for battery performance improvement and the corresponding mechanistic understanding. Here, highly crystalline VS₂ nanosheets/carbon nanotubes (CNTs) with a core/branch structure were synthesized, exhibiting reversible discharge capacity of ∼850 mA h g^-1 at 200 mA g^-1, high coulombic efficiency of ∼98%, good cycling stability and superior rate capability. The relationship between the electrochemical properties and the corresponding dynamic microstructural evolution was further revealed with the in situ electron microscopy technique. Our results showed that the intercalation process with the formation of amorphous Li_xVS₂ and the subsequent conversion reactions with the formation of crystalline Li₂S and V nanocrystals occurred during the discharging process. Crystalline Li₂S was oxidized in the charging process. The core/branched structure ensured a large exposed surface area of the VS₂ nanosheets and provided extra space to accommodate the volume expansion. Meanwhile, the CNTs surrounded by VS₂ nanosheets not only provided a continuous and fast conducting pathway for carriers throughout the electrodes, but also enhanced the mechanical stability of the electrode material. These factors finally contributed to the superior electrochemical performance of the core/branch-structured VS₂/CNTs electrode.

In Situ Generated Li2S-C Nanocomposite for High-Capacity and Long-Life All-Solid-State Lithium Sulfur Batteries with Ultrahigh Areal Mass Loading

All-solid-state lithium-sulfur batteries (ASSLSBs) have attracted great attention due to their inherent ability to eliminate the two critical issues (polysulfide shuttle effect and safety) of traditional liquid electrolyte based Li-S batteries. However, it remains a huge challenge for ASSLSBs to achieve high areal active mass loading and high active material utilization simultaneously due to the insulating nature of sulfur and Li₂S, and the large volume change during cycling. Herein, a Li₂S@C nanocomposite with Li₂S nanocrystals uniformly embedded in conductive carbon matrix, is in situ generated by the combustion of lithium metal with CS₂. Benefiting from its unique architecture, the Li₂S@C exhibits exceptional electrochemical performance as cathode for ASSLSBs, with both ultrahigh areal Li₂S loading (7 mg cm^-2) and 91% of Li₂S utilization (corresponding to a reversible capacity of 1067 mAh g^-1). Moreover, the Li₂S@C also possesses outstanding rate capability and cycling stability. High reversible capacity of 644 mAh g^-1 is delivered at 2 mA cm^-2 even after 700 cycles. This work demonstrates that ASSLSBs with superior electrochemical performance can be realized via rational design of the cathode structure, which provides a promising prospect to the development of ASSLSBs with practical energy density surpassing that of lithium ion batteries.

PEDOT-PSS coated VS2 nanosheet anodes for high rate and ultrastable lithium-ion batteries

A high rate and ultrastable anode material is successfully synthesized by encapsulating VS₂ nanosheets into a PEDOT-PSS shell.

LiCrS2 and LiMnS2 Cathodes with Extraordinary Mixed Electron-Ion Conductivities and Favorable Interfacial Compatibilities with Sulfide Electrolyte

Sulfide-type solid-state electrolytes for all-solid-state lithium ion batteries are capturing more and more attention. However, the electronegativity difference between the oxygen and the sulfur element makes sulfide-type solid-state electrolytes chemically incompatible with the conventional LiCoO₂ cathode. In this work, we proposed a series of chalcopyrite-structured sulfide-type materials and systematically assessed their performances as the cathode materials in all-solid-state lithium ion batteries by first-principle calculations. All the five metallic LiMS₂ (M = Cr, Mn, Fe, Co, and Ni) materials are superionic conductors with extremely small lithium ion migration barriers in the range from 43 to 99 meV, much lower than most oxide- and even sulfide-type cathodes. Voltage and volume calculations indicate that only LiCrS₂ and LiMnS₂ cathodes are structurally stable during cycling with the stable voltage plateaus at ∼3 V, much higher than that of the P3m1-LiTiS₂ cathode. For the first time, we studied the interfacial lithium transport resistance from a new perspective of charge transfer and redistribution at the electrode/solid-state electrolyte interface. LiCrS₂ and LiMnS₂ cathodes exhibit favorable interfacial compatibilities with Li₃PS₄ electrolyte. Our investigations demonstrate that the metallic LiCrS₂ and LiMnS₂ superionic conductors would possess excellent rate capability, high energy density, good structural stability during cycling, and favorable interfacial compatibility with Li₃PS₄ electrolyte in all-solid-state lithium ion batteries.