Boosting the synergistic activation of δ-MnO2 as cathode for aqueous zinc-ion batteries through Ni, Co co-doping

Layered δ-MnO2 is regarded as a promising cathode material for high-performance aqueous zinc-ion batteries (AZIBs) due to the sufficient interlayer spacing for the accommodation and migration of charge carriers. However, the sluggish activation process limits the reversible capacity, thus prevent their application. In this study, Ni-Co co-doped layered δ-MnO2 was designed to enhance ion diffusion capability and cycling stability. The influencing mechanism of Ni and Co on the long activation process are proposed by a comparative analysis between single doping and co-doping approaches. Specifically, the optimized co-doped δ-MnO2 maintained a high specific capacity of 200.2 mAh·g−1 with a capacity retention of 97.40 % after 700 cycles at 1 A·g−1. The co-doping approach exhibited a synergistic effect in suppressing Mn dissolution and enhancing ion diffusion capability. These findings provide new directions on boosting the synergistic activation process of manganese oxide and shed lights on the rational design of low-cost and high-safe batteries.