Oxygen vacancy regulated TiNb2O7 compound with enhanced electrochemical performance used as anode material in Li-ion batteries

Abstract TiNb2O7 compound with extra oxygen vacancies is synthesized through unique supercritical fluid process. When fabricated as anode for lithium ion batteries, such TiNb2O7 anode exhibits high initial discharge capacity of 231 mA h g−1 at a current density of 100 mA g−1, and maintains capacity of 169 mA h g−1 even after 250 cycles in the voltage window of 1.0–3.0 V. The excellent electrochemical performance is mainly attributed to the existence of abundant oxygen vacancies in TiNb2O7 compound, which greatly increases the electronic conductivity and lithium ion diffusion coefficient. Furthermore, the contribution of pseudocapacitive effect to the superior electrochemical performance of as-prepared Ti Nb2O7 is investigated systematically. All in all, it demonstrates that the supercritical fluid is a facile and effective media to create oxygen vacancies in TiNb2O7, and the TiNb2O7 compound with introduced oxygen vacancies would be a promising candidate for anode materials in high-power lithium ion batteries. This work provides a fresh strategy and route to explore novel multicomponent oxide materials with enhanced electrochemical properties for energy storage.