Interface regulated MnO2/Mn2+ redox chemistry in aqueous Zn ion batteries

Due to the rapid development of energy storage systems from the goal of carbon neutrality, rechargeable aqueous Zn-MnO 2 batteries have attracted growing attention. While the controversy surrounding various mechanisms, such as Zn 2+ insertion, Zn 2+ /H + co-insertion and Mn dissolution/deposition, leads to limitation of MnO 2 cathodes, especially for the β-MnO 2 . Though showing promising performance in recent works, the reaction process and influence factors of β-MnO 2 cathodes are still under debate. In this work, a complete MnO 2 /Mn 2+ redox chemistry is proposed to explain the abnormal electrochemical behaviors of β-MnO 2 cathodes, which indicates the reversible dissolution/deposition of layered manganese oxides appears after the initial MnO 2 dissolution reaction. The revealed effects of interfacial environment in regulating the electrochemical reactions also provide a new perspective for studying the working mechanism of aqueous Zn-MnO 2 batteries. Besides, the high specific capacity shown in the MnO 2 /Mn 2+ redox chemistry also contributes to designing high-performance cathodes for AZIBs.