Impact of Ni on the structure and electrochemical behavior of δ-MnO2 cathodes in zinc ion batteries

Abstract

The utilization of MnO₂ as a cathode material in energy storage systems such as rechargeable aqueous zinc-ion batteries shows great promise for development due to its high safety, environmental friendliness, and cost-effectiveness. Nevertheless, the manganese dioxide cathode suffers from a dissolution-redeposition reaction, leading to poor structural stability. To address these issues, this study focuses on modifying the structural properties of δ-MnO₂ to overcome its drawbacks, such as low capacity and cycling stability. By synthesizing Ni-δ-MnO₂ with enhanced crystalline structure, expanded lattice spacing, improved conductivity, rapid diffusion of Zn²⁺ ions, and electron transfer are enabled. This results in a notable high capacity of 350 mA h g⁻¹ at 50 mA g⁻¹, accompanied by enduring cycle stability, with the capacity maintained over 200 cycles. The morphology evolution and structure of Ni- δ-MnO₂ are believed to enhance ion transportation, rendering it a promising cathode material for applications in aqueous zinc-ion batteries.