Enhanced electrochemical performance of MnO2 by high oxidation state vanadium(Ⅴ) doping

Abstract

Due to the poor conductivity, α-MnO2 exhibits a low specific capacity and bad rate performance, meantime, the repeated insertion/extraction of Zn2+ in MnO2 results in the collapse of its tunnel structure, leading to the rapid decay of cyclic performance, which seriously affects the practical application of aqueous Zn-MnO2 batteries. Studies have shown that doping is an effective method to improve the electrochemical properties of MnO2. As we have learned, the current studies mainly adopt low oxidation state cations (such as Ni2+, Co2+, Zn2+,Ca2+, K+ and Al3+). Herein, high oxidation state Vanadium(Ⅴ) was used for doping, the resulted Manganese and Oxygen vacancies enhanced the diffusion of Zn2+ and improved the reversibility and rate performance of MnO2. When cycled at 3 C (1 C = 308 mA g−1), the specific capacity of V-MnO2(0.06) kept stable at 300 mAh g−1 and there was no indication of any evidence of decay, even if proceeded 400 cycles. High-oxidation-state Vanadium(Ⅴ) doping and resulted vacancy defects synergistically improved the electrochemical properties of MnO2, providing new ideas for MnO2 modification.