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

In aqueous zinc-ion batteries (AZIB), layered manganese dioxide (δ-MnO2) is considered as 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 δ-MnO2 results in slow diffusion dynamics of Zn2+ in the electrochemical process, which will affect the structural stability of the cathode. Herein, we report a structural design that stabilizes the δ-MnO2 layered structure by pre-intercalation of Cu2+ to expand the layer spacing, and thus improves the H+ transfer kinetics. Compared with the bulk δ-MnO2, the modified cathode shows excellent electrochemical performances including a high reversible capacity of 280 mAh g-1 at 1A g-1 and 62.5% capacity retention after 1500 cycles at 5A g-1. The results above confirm the possibility of increasing the capacity contribution of H+ through structural design, and provide a novel idea for the development of high-performance cathode materials.