Ion-exchange induced Ni doping of α-MnO2 cathode with structural modification for aqueous zinc ion batteries

Manganese-based cathode materials for zinc-ion batteries provide a moderate voltage window and good specific capacity. However, the disproportionation reactions cause manganese to dissolve during the charge and discharge process, seriously affecting its cycle stability. Herein, nickel-doped α phase manganese dioxide (Ni-MnO 2 ) obtained by ion exchange effectively improves the lattice stability and cycle stability of manganese dioxide (MnO 2 ). The introduction of Ni 2+ supports the lattice structure of MnO 2 , reduces structural damage and manganese (Mn) dissolution caused by the Jahn-Teller effect during the cycle, and improves its electronic conduction and ion migration capabilities. It quickly completes the activation process at a current density of 0.1 A g −1 and stably maintains a capacity of 233 mAh g −1 . After 2800 cycles at 1 A g −1 , the capacity retention rate remains 96.3 %. In contrast, MnO 2 without ion exchange modification has dropped to 19.6 % after 130 cycles. This paper demonstrates the feasibility of the ion exchange process, bringing more precise and effective ideas to the research and development of high-performance aqueous zinc-manganese batteries.