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

Abstract

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.