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

Due to the poor conductivity, α-MnO ₂ exhibits a low specific capacity and bad rate performance, meantime, the repeated insertion/extraction of Zn ²⁺ in MnO ₂ 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-MnO ₂ batteries. Studies have shown that doping is an effective method to improve the electrochemical properties of MnO ₂ . As we have learned, the current studies mainly adopt low oxidation state cations (such as Ni ²⁺, Co ²⁺, Zn ²⁺,Ca ²⁺, K ⁺ and Al ³⁺ ). Herein, high oxidation state Vanadium(Ⅴ) was used for doping, the resulted Manganese and Oxygen vacancies enhanced the diffusion of Zn ²⁺ and improved the reversibility and rate performance of MnO ₂. When cycled at 3 C (1 C = 308 mA g ⁻¹), the specific capacity of V-MnO ₂(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 MnO ₂, providing new ideas for MnO ₂ modification.