Metal-Organic Assembly Strategy for the Synthesis of Layered Metal Chalcogenide Anodes for Na+ /K+ -Ion Batteries

Layered transition metal chalcogenides (MX, M=Mo, W, Sn, V; X=S, Se, Te) have large ion transport channels and high specific capacity, making them promising for large-sized Na⁺ /K⁺ energy-storage technologies. Nevertheless, slow reaction kinetics and huge volume expansion will induce an undesirable electrochemical performance. Numerous efforts have been devoted to designing MX anodes and enhancing their electrochemical performance. Based on the metal-organic assembly strategy, nanostructural engineering, combination with carbon materials, and component regulation can be easily realized, which effectively boost the performance of MX anodes. In this Review, we present a comprehensive overview on the synthesis of MX nanostructure using the metal-organic assembly strategy, which can realize the design of MX nanostructures, based on self-sacrificial templates, host@guest tailored templates, post-modified layer and derivative templates. The preparation routes and structure evolution are mainly discussed. Then, Mo-, W-, Sn-, V-based chalcogenides used for Na⁺ /K⁺ energy storage are reviewed, and the relationship between the structure and the electrochemical performance, as well as the energy storage mechanism are emphasized. In addition, existing challenges and future perspectives are also presented.

Recent Progress in Rechargeable Sodium Metal Batteries: A Review

Sodium metal batteries (SMBs) have been widely studied owing to their relatively high energy density and abundant resources. However, they still need systematic improvement to fulfill the harsh operating conditions for their commercialization. In this review, we summarize the recent progress in SMBs in terms of sodium anode modification, electrolyte exploration, and cathode design. Firstly, we give an overview of the current challenges facing Na metal anodes and the corresponding solutions. Then, the traditional liquid electrolytes and the prospective solid electrolytes for SMBs are summarized. In addition, insertion- and conversion-type cathode materials are introduced. Finally, an outlook for the future of practical SMBs is provided.

Vanadium Tetrasulfide for Next-Generation Rechargeable Batteries: Advances and Challenges

Alkali metal-ion batteries (SIBs and PIBs) and multivalent metal-ion batteries (ZIBs, MIBs, and AIBs), among the next-generation rechargeable batteries, are deemed appealing alternatives to lithium-ion batteries (LIBs) because of their cost competitiveness. Improving the electrochemical properties of electrode materials can greatly accelerate the pace of development in battery systems to cover the increasing demands of realistic applications. Vanadium tetrasulfide (VS₄ ) is known as a prospective electrode material due to its unique one-dimensional atomic chain structure with a large chain spacing, weak interactions between adjacent chains, and high sulfur content. This review summarizes the synthetic strategies and recent advances of VS₄ as cathodes/anodes for rechargeable batteries. Meanwhile, we describe the structural characteristics and electrochemical properties of VS₄ . And we describe in detail its specific applications in batteries such as SIBs, PIBs, ZIBs, MIBs, and AIBs as well as modification strategies. Finally, the opportunities and challenges of VS₄ in the domain of energy research are described.

Design and Synthesis of a Reduced Graphene Oxide/Patronite Composite with Enhanced Lithium-Ion Storage Performance

The construction of graphene-based composites is a novel electrode material design strategy and has become a promising field in new energy material research. However, the rational design principle is still poorly understood, and the synthetic technology urgently needs to be expanded. Here, a novel strategy for the synthesis of a reduced graphene oxide (rGO)/VS₄ nanoparticle (NP) composite is reported using an ionic liquid (IL)-assisted hydrothermal method. The synergistic effects of graphene and IL, which include the π-cation/anion interactions of graphene, the capping agent effect of IL, and their π-π stacking interaction, are responsible for the synthesis of the composite, achieving delicate tailoring of VS₄ NPs as well as their homogeneous dispersal on the surface of rGO nanosheets. The superior nanostructure of the composite results in enhanced lithium-ion storage performance, such as improved cyclic stability (1009 mA h g^-1 at 0.1 A g^-1 after 150 cycles and 788 mA h g^-1 after 240 cycles even at 1 A g^-1) and rate capability (1540 and 621 mA h g^-1 at 0.1 and 2 A g^-1, respectively). This strategy provides an effective new approach for designing graphene composites and is expected to be applicable in the design of other rGO/transition-metal sulfide composites for energy storage.

Construction of Hierarchical Nanotubes Assembled from Ultrathin V3 S4 @C Nanosheets towards Alkali-Ion Batteries with Ion-Dependent Electrochemical Mechanisms

Ultrathin core-shell V₃ S₄ @C nanosheets assembled into hierarchical nanotubes (V₃ S₄ @C NS-HNTs) are synthesized by a self-template strategy and evaluated as general anodes for alkali-ion batteries. Structural/physicochemical characterizations and DFT calculations bring insights into the intrinsic relationship between crystal structures and electrochemical mechanisms of the V₃ S₄ @C NS-HNTs electrode. The V₃ S₄ @C NS-HNTs are endowed with strong structural rigidness owing to the layered VS₂ subunits and interlayer occupied V atoms, and efficient alkali-ion adsorption/diffusion thanks to the electroactive V₃ S₄ -C interfaces. The resulting V₃ S₄ @C NS-HNTs anode exhibit distinct alkali-ion-dependent charge storage mechanisms and exceptional long-durability cyclic performance in storage of K⁺ , benefiting from synergistic contributions of pseudocapacitive and reversible intercalation/de-intercalation behaviors superior to those of the conversion-reaction-based Li⁺ -/Na⁺ -storage counterparts.

Fibrous Network of C@MoS2 Nanocapsule-Decorated Cotton Linters Interconnected by Bacterial Cellulose for Lithium- and Sodium-Ion Batteries

To protect the structure of MoS₂ from collapse, a strong skeleton is expected to help maintain the integrity. In this study, cotton linters burdened with hollow C@MoS₂ nanocapsules are added into nutrient medium for the growth of a bacterial cellulose membrane. Benefitting from good conductivity and structural integrity, the resultant fibrous membrane anode gives reversible capacities of 559 and 155 mAh g^-1 for Li-ion batteries and Na-ion batteries after 100 cycles, respectively. The structural transformation and component evolution in lithiation-delithiation and sodiation-desodiation was elucidated by in situ Raman spectroscopy. After sodiation, the Na₂ S did not transform back into MoS₂ but was more likely converted into elemental sulfur during the conversion reaction. Layered semiconducting transition metal chalcogenides, such as molybdenum disulfide (MoS₂ ), feature open 2 D ion-transport channels amenable to receive various guest ions with high theoretical capacities.^[2] One serious challenge curtailing the applicability of such materials is their volume changes during discharge-charge processes.^{[3, 4]} However, particular morphologies of MoS₂ are proposed to improve the specific capacity.^[5,6,7] Many works have focused on core-shell and hollow MoS₂ micro- and nanostructures, and the results validate the advantages of shortening the lithium-ion diffusion distance and enhancing specific capacity.^[8,9] Unfortunately, the issue of inferior capacity stability is not resolved, because the structure is not effectively protected and is prone to collapse.