Rich bulk oxygen Vacancies-Engineered MnO2 with enhanced charge transfer kinetics for supercapacitor

Transition metal oxides with high theoretical capacity are known to show greatly limited energy and power density of electrochemical energy storage due to its sluggish charge transfer kinetics. Although oxygen vacancies at atomic level can efficiently regulate electronic configuration and ameliorate electrochemical performance, the construction of rich bulk oxygen vacancies is still a challenge. Here, rich oxygen vacancies were successfully introduced in bulk MnO2 through complex induced chemical precipitation. Enhanced electrical conductivity and local electric-field formed around oxygen vacancies promote the charge transfer, remarkably enhancing capacitance and rate capability. Asymmetric supercapacitor of MnO2 with rich bulk oxygen vacancies exhibits high energy density (54.2 Wh kg−1) and power density (3279.6 W kg−1), superior to most reported MnO2-based supercapacitor. Our strategy paves a way for the fine regulation of bulk electronic configuration and reaction kinetics.