Opportunities for Aqueous Electrolytic Zinc–Manganese Batteries

Aqueous electrolytic zinc–manganese batteries (AZMBs) have attracted significant interest as promising candidates for practical large-scale energy storage due to their intrinsic safety and high energy density. However, the poor electric conductivity and sluggish electroreduction kinetics of MnO2 lead to poor reversibility of the Mn2+/MnO2 conversion reaction, greatly restricting the development of practical AZMBs. Recently, diverse strategies have been proposed to enhance the reversibility of Mn2+/MnO2 conversion by addressing the aforementioned issues. Nevertheless, existing literature has generally lacked a systematic elucidation of the complex chemical−electrochemical mechanisms governing this conversion reaction. Furthermore, critical assessments of the efficacy and inherent limitations in these strategies, as well as comprehensive analyses of their impacts on battery performance, remain insufficient. Through an in-depth elucidation of the Mn2+/MnO2 conversion mechanism, this Review explores several promising research directions aiming to provide valuable insights and perspectives for advancing the technology and practical implementation of AZMBs.