Stabilizing high-areal-capacity manganese dioxide cathodes in near-neutral Zn-ion batteries: A synergy of lattice doping and surface coating

Rechargeable aqueous Zn||MnO 2 batteries using near-neutral electrolytes have attracted considerable interest owing to their environmental benignity and high safety. However, MnO 2 cathodes with high mass loading suffer from sluggish reaction kinetics and structural degradation during long-term cycling, particularly under low-current-density conditions. Limited ion diffusion in thick electrodes results in capacity fading, while slow proton intercalation aggravates irreversible phase transitions, leading to active material dissolution and rapid capacity loss. To address these challenges, we propose a dual-modification strategy involving Ce doping and reduced graphene oxide (rGO) coating. The charge compensation effect induced by Ce doping increases the Mn 3+ /Mn 4+ ratio in MnO 2 from 0.36 to 0.61, effectively optimizing the electronic structure and improving lattice stability. Meanwhile, the constructed three-dimensional rGO conductive network reduces interfacial charge-transfer resistance and alleviates volume strain during cycling. Benefiting from this synergistic effect, the composite cathode achieves an areal capacity of 2.05 mAh cm −2 at 0.1C and retains 77.8 % of its initial capacity over 507 cycles at 2 C. This work offers a novel synergistic strategy for designing high-mass-loading cathodes and advances the practical implementation of Zn||MnO 2 batteries in grid-scale energy storage.