A comparison study of MnO₂ and Mn₂O₃ as zinc-ion battery cathodes: an experimental and computational investigation

Abstract

The high specific capacity, low cost and environmental friendliness make manganese dioxide materials promising cathode materials for zinc-ion batteries (ZIBs). In order to understand the difference between the electrochemical behavior of manganese dioxide materials with different valence states, <i>i.e.</i>, Mn(iii) and Mn(iv), we investigated and compared the electrochemical properties of pure MnO₂ and Mn₂O₃ as ZIB cathodes <i>via</i> a combined experimental and computational approach. The MnO₂ electrode showed a higher discharging capacity (270.4 mA h g^-1 at 0.1 A g^-1) and a superior rate performance (125.7 mA h g^-1 at 3 A g^-1) than the Mn₂O₃ electrode (188.2 mA h g^-1 at 0.1 A g^-1 and 87 mA h g^-1 at 3 A g^-1, respectively). The superior performance of the MnO₂ electrode was ascribed to its higher specific surface area, higher electronic conductivity and lower diffusion barrier of Zn²⁺ compared to the Mn₂O₃ electrode. This study provides a detailed picture of the diversity of manganese dioxide electrodes as ZIB cathodes.