Manganese oxides hierarchical microspheres as cathode material for high-performance aqueous zinc-ion batteries

Abstract

For manganese-based oxides to be used as one of the most promising aqueous zinc-ion batteries (ZIBs) cathode materials, improvements in cycling stability are required. In this work, manganese oxides (MnOx) hierarchical microspheres, including MnO, γ-MnO2 (MnO2), Mn2O3 and Mn3O4, are prepared and their electrochemical performances are systematically investigated as cathode materials for aqueous ZIBs. The MnOx hierarchical structures can effectively shorten the diffusion pathway of Zn2+, tolerate the structural stress caused by Zn2+ insertion/extraction and restrain the self-aggregation of nanomaterials. Among MnOx, MnO hierarchical microspheres displays a high reversible capacity of 376.7 mAh g−1, good rate capability and excellent cycling stability with capacity retention of 99.37% over 1000 cycles. Finally, the zinc ion storage mechanism of MnO cathode is revealed. The results show that the remarkable electrochemical performance of MnO cathode is attributed to layered-type MnO2 structure formed during the initial few cycles, which is conducive to the insertion/extraction of zinc ions. This work is expected to deepen the understanding of the energy storage mechanism of MnO and helped to choose the ideal manganese-based cathode materials for aqueous ZIBs.