Advancing Mn²⁺/MnO₂ Conversion Chemistry through Redox Mediation: Mechanistic Insights and Outlook

Electrolytic MnO2 batteries based on a two-electron-transfer Mn2+/MnO2 conversion reaction have been attracting growing research interests for large-scale applications due to high voltage and high capacity. However, the low Mn2+/MnO2 conversion efficiency caused by incomplete MnO2 dissolution hinders its practical applications. Recently, redox mediation chemistry has been introduced to improve Mn2+/MnO2 conversion capacity by orders of magnitude. However, as an emerging key strategy, the complex solid–liquid conversion mechanism, the interactions between the redox mediator and the Mn-based species, and the influence of the interfacial environment remain poorly understood. This perspective article aims to discuss critical evaluation criteria, outline key research directions, and summarize relevant characterization methods for redox mediation chemistry in Mn2+/MnO2 conversion. Several future focuses on design principles for high-energy Mn-based cathode materials are proposed. We hope to use a Mn2+/MnO2 system as a model platform to deepen scientific understanding of redox-mediated conversion reactions and inspire broader research in this field.