The role of Cu ions of the self-reassembled MnO2 nanosheets for rechargeable aqueous batteries

Abstract

Abstract Cu 2+ ions inserted MnO 2 electrodes (Cu-NS-MnO 2 ) were prepared via nanosheet processes, and their electrochemical properties were investigated. In basic aqueous solutions, layer-structured MnO 2 compounds usually show the irreversible phase transformation into Mn 3 O 4 phase with a rapid decrease in a capacity. In this study, however, the Cu-NS-MnO 2 showed relatively good cyclic properties with slow phase transformation at KOH solution. The Cu-NS-MnO 2 exhibited a large discharge capacity of 230 mAh/g-MnO 2 at the first cycle, and maintained a specific capacity of 170 mAh/g-MnO 2 after 10 cycles at a current density of 300 mA/g-MnO 2 . These results suggest that Cu ions and nanosheet processes have effects to inhibit the irreversible phase transformation into Mn 3 O 4 phase and maintain electrochemical activity under the basic condition. In this study, the role of Cu ions on electrochemical properties of the self-reassembled MnO 2 nanosheets was investigated.