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

Abstract

Rich bulk oxygen vacancies can enhance electrical conductivity and promote electron transfer. Local electric-field formed around oxygen vacancies can accelerate Na + transfer rate in bulk MnO 2 , and induce a decreased Na + diffusion energy barrier. Both of the enhanced electron and Na + transfer kinetics can ameliorate energy storage performance of MnO 2 . • Rich bulk oxygen vacancy is achieved by complex induced chemical precipitation. • Enhanced electrical conductivity of MnO 2 -C is obtained. • Robust local electric-field ameliorates the charge transfer kinetics. 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 MnO 2 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 MnO 2 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 MnO 2 -based supercapacitor. Our strategy paves a way for the fine regulation of bulk electronic configuration and reaction kinetics.