Multi-scale Regulation of MnO2 Dissolution/Deposition Chemistry in Rechargeable Aqueous Zinc Ion Batteries

Abstract

Electrolytic zinc-manganese dioxide (Zn–MnO2) batteries represent a promising candidate for large-scale energy storage due to their large specific capacity and high discharge voltage plateau. However, the irreversible dissolution/deposition chemistry of MnO2 cathode causes rapid capacity decay and shortened lifespan, which severely constrains their practical application. This review systematically summarizes recent advances in multi-scale regulation strategies aimed at achieving reversible MnO2/Mn2+ conversion. After deliberately illustrating the distinctive merits of the cathodic MnO2/Mn2+ chemistry and its associated key challenges, we begin with elucidating electrolyte-mediated regulation, focusing on dynamic pH control, Mn2+ concentration optimization, functional additives, and innovative electrolyte decoupling designs, which collectively tailor the interfacial environment to stabilize the two-electron MnO2/Mn2+ redox couple. The discussion then shifts to intrinsic electrode material strategies, detailing how microstructure design, surface modifications, and composite electrode architectures influence the electronic conductivity, structural stability, and reaction kinetics of MnO2. Finally, we provide a forward-looking perspective on future research priorities, with special emphasis on the structure-performance relationship analyses, to accelerate the deployment of high-performance Zn-MnO2 batteries.