Recent Advancements in Ion Doping Strategies for Manganese Dioxide-Based Cathodes in Aqueous Zinc-Ion Batteries

Abstract

Due to its low cost and high electrochemical window, manganese dioxide (MnO₂) is a promising cathode material for rechargeable aqueous zinc-ion batteries (AZIBs). However, the MnO₂ cathode suffers from crystal structure distortion and active material loss induced by the Jahn–Teller effect, as well as sluggish kinetics resulting from low intrinsic conductivity. To address these issues, researchers propose ion-doping strategies to regulate the intrinsic properties of MnO₂. This article reviews recent advancements in ion-doping strategies, categorized into metal ion doping, nonmetal ion doping, and multi-ion co-doping. Critically, this review differentiates between lattice substitution and interstitial occupancy and systematically analyzes the quantitative correlation between doping concentration and electrochemical performance, providing a roadmap for optimizing dopant efficacy. Finally, the review provides an outlook on current challenges and future research directions for developing high-performance MnO₂ cathodes.