Copper ions-intercalated manganese dioxide self-supporting mesoporous carbon electrode for aqueous zinc-ion batteries

Abstract

The insertion of copper ions expands the layer spacing of MnO 2 , stabilizes the structure of MnO 2 , enhances the diffusion ability of H + , and thus exhibits excellent electrochemical properties. In aqueous zinc-ion batteries (AZIB), layered manganese dioxide (δ-MnO 2 ) is considered to be a suitable cathode material due to its high theoretical capacity, suitable operating voltage and Zn 2+ /H + co-intercalation mechanism. However, the strong coulomb interaction between Zn 2+ and δ-MnO 2 results in the slow diffusion dynamics of Zn 2+ in the electrochemical process, which affects the structural stability of the cathode. Herein, we report a structural design that stabilizes the δ-MnO 2 -layered structure by pre-intercalation of Cu 2+ to expand the layer spacing, and thus improve H + -transfer kinetics. Compared with the bulk δ-MnO 2 , the modified cathode showed excellent electrochemical performances, including a highly reversible capacity of 280 mA h g −1 at 1 A g −1 and 62.5% capacity retention after 1500 cycles at 5 A g −1 . The results shown above confirmed the possibility of increasing the capacity contribution of H + through structural design, and provides a novel idea for the development of high-performance cathode materials.