Zn/MnO2 battery chemistry with dissolution-deposition mechanism

Rechargeable Zn/MnO2 battery chemistry in mildly acidic aqueous electrolytes has attracted extensive attention because of its properties as safe, inexpensiveness, and high theoretical specific capacity of cathode/zinc anode. However, the major limitation of MnO2 cathode is its unclear energy storage mechanism. Herein, the reaction mechanism in ZnSO4+MnSO4 electrolyte is investigated by various electrochemical and structural analysis based on two different structure manganese dioxide (α-MnO2 and δ-MnO2) and Zn4SO4(OH)6·4H2O (ZHS) prepared on purpose. We find that the Zn/MnO2 battery is dominated by the Dissolution-Deposition reaction mechanism, while the classical cations (H+, Zn2+) Intercalation/De-intercalation mechanism contributes little capacity in energy storage process. The major limitations of reaction kinetics, such as ZHS and active H2O, are explored in this work. We believe that the systematic research on the Dissolution/Deposition mechanism is useful for researchers to understand the energy storage mechanism of Zn/MnO2 battery.