Efficient Lithium/Sodium-Ion Storage by Core-Shell Carbon Nanospheres@TiO2 Decorate by Epitaxial WSe2 Nanosheets Derived from Bimetallic Polydopamine Composites

Anchoring tungsten oxide nanorods on TiO2 nanowires coupled with carbon for efficient lithium-ion storage

Reasonable construction of hierarchical electrode materials is verified as a promising way to improve the electrochemical performance due to the synergistic effect between unique components and constructions. Hence, a hierarchical nanostructure composed of tungsten oxide nanorods anchored on TiO2 nanowires coupled with a carbon layer (TiO2@WOx-C NWs) was synthesized as an electrode material by exploiting the self-assembly function of dopamine and carbonization. The inner one-dimensional TiO2 nanowires served as the stable substrate with WOx anchored on the surface of TiO2 NWs and the tightly coupled carbon nanosheets, which can not only facilitate electron transport but also provide more active sites for electrochemical reactions. As a result, benefitting from the synergistic effects between three functional components and the multi-dimensional hierarchical structures, the as-prepared TiO2@WOx-C NWs displayed excellent lithium storage performance with a specific capacity of 651.4 mA h g-1 after 500 cycles at 1.0 A g-1, which is superior to most Ti-based structures. The enhanced electrochemical performance is mainly attributed to the synergistic effect of the different dimensional structures, the high capacity of tungsten oxide and the surface coating of the conductive carbon material. This work provides a simple and effective approach to designing functional hierarchical structures for energy storage and conversion.

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.