Influence of Co on the Microstructure, Electrochemical and Pseudocapacitive Properties of Amorphous Manganese Dioxide

Abstract

Manganese dioxide is a cathode material for zinc-ion batteries which is low in cost and high in performance, whereas, traditional manganese dioxide materials have poor cycle stability and poor conductivity. In response to this problem, many researchers have carried out related research, such as the preparation of various crystal forms of manganese dioxide, element doping (Co, Sn, V, etc.) and so on. However, the research on doping amorphous materials to solve the above problems is in scarcity. In this paper, amorphous manganese oxide and Co doping were combined for the first time, and Co-doped amorphous manganese dioxide was prepared by in-situ liquid phase dispersion coprecipitation method. The influence of Co doping on the microstructure and electrochemical properties of amorphous manganese dioxide were also investigated for the first time. As can be observed from the results, despite that Co doping preserves the abundant structural defects in amorphous manganese dioxide, it transforms the amorphous manganese dioxide particles from spherical to nano-sheet shape, significantly increases the particular area of surface and pore size of amorphous manganese dioxide, and stabilizes its crystal structure. Furthermore, Co doping can not only reduce the impedance of the amorphous manganese dioxide cathode, but also extremely boost the pseudocapacitive performance of amorphous manganese dioxide, thereby greatly improving its discharge specific capacity, the rate performance and the cycle stability. The prepared Co-doped amorphous manganese dioxide cathode has a maximum discharge specific capacity of 325 mAh g−1, and a capacity retention rate of 64% at 600 cycles under a current density of 1 A g−1.