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

In aqueous zinc-ion batteries (AZIB), layered manganese dioxide (delta-MnO2) is considered to be a suitable cathode material due to its high theoretical capacity, suitable operating voltage and Zn2+/H+ co-intercalation mechanism. However, the strong coulomb interaction between Zn2+ and delta-MnO2 results in the slow diffusion dynamics of Zn2+ in the electrochemical process, which affects the structural stability of the cathode. Herein, we report a structural design that stabilizes the delta-MnO2-layered structure by pre-intercalation of Cu2+ to expand the layer spacing, and thus improve H+-transfer kinetics. Compared with the bulk delta-MnO2, 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.Keywords: Aqueous zinc-ion batteries; Layered manganese dioxide; Pre-intercalation; Self-supporting electrode.