Micro/nanostructured TiNb2O7-related electrode materials for high-performance electrochemical energy storage: recent advances and future prospects

摘要

The increasing demand for large-scale electrochemical energy storage, such as lithium ion batteries (LIBs) for electric vehicles and smart grids, requires the development of advanced electrode materials. Ti-Nb-O compounds as some of the most promising intercalation-type anode materials have attracted a lot of attention owing to their high theoretical capacity (388-399 mA h g(-1)) arising from the multiple redox pairs (Ti4+/Ti3+, Nb5+/Nb4+, and Nb4+/Nb3+), high safety, and superior cycling stability. However, their intrinsic low electronic conductivity and slow solid-state ion diffusion lead to unsatisfactory rate performance. To overcome these drawbacks, various efficient strategies have been proposed to improve the performance of Ti-Nb-O compounds, especially TiNb2O7. This Review aims to provide rational understanding of how structural engineering approaches (e.g., dimensional/morphological control, doping/hybridizing with exotic elements/components, carbon coating/compositing,etc.) improve the electrochemical properties of micro/nanostructured TiNb2O7-based anode materials. In addition, other Ti-Nb-O compounds with different compositions as anodes for LIBs and micro/nanostructured TiNb2O7-based anodes for other energy storage systems (sodium-ion batteries, hybrid supercapacitors, and vanadium redox flow batteries) are discussed. Finally, the challenges and opportunities for micro/nanostructured TiNb2O7-related electrode materials for high-performance energy storage applications are highlighted.