Trace Water‐induced Morphology Engineering and Oxygen Vacancy for Enhancing the Capacity of Bi2O3 Alkaline Battery‐Anode

Bi2O3 is a theoretically high capacitive anode material; however, its low conductivity and deficient surface-active sites lead to reduced practical capability compared to the theoretical one. Herein, a facile and environmentally benign strategy is developed to simultaneously tailor the morphology and create oxygen vacancies in Bi2O3 by adding trace water in a solvothermal procedure. Trace water serves as an intermediary agent to change the growth mechanism of Bi2O3 and form a hierarchical structure with increased crystallinity. Electrochemical experiments reveal that the optimal tremella-shaped Bi2O3 delivers a higher specific capacity, approximately reaching 65% of the theoretical one. Such satisfactory electrochemical performance is due to the regulated tremella shape and the created oxygen vacancies, which can expose more electrochemical active-sites and promote ion diffusion. Moreover, the massive oxygen vacancies and increased crystallinity are also beneficial for electron transfer, thus enhancing the capacity. Eventually, a Bi2O3//AC asymmetric device is constructed and a superior energy density (40.8 W h kg-1) is realized than the others Bi2O3-based peers. This study paves a facile way for exploring advanced Bi2O3-based alkaline battery anode materials through an environmentally benign method.