Dynamic compensation of MnOOH to mitigate the irregular dissolution of MnO2 in rechargeable aqueous Zn/MnO2 batteries

As a recognized promising cathode material for rechargeable aqueous Zn batteries, an MnO2 cathode often suffers from rapid fading of capacity due to irreversible Mn dissolution, which hinders high-performance Zn batteries. Herein, we introduced Ce(SO4)2 additives into the electrolyte of Zn/MnO2 batteries to cope with the irreversible dissolution of MnO2. During charging, the MnOOH formed by the reaction between Ce4+ and Mn2+ deposited on the cathode with the attraction of H+ and was converted subsequently to MnO2 to achieve dynamic compensation. Meanwhile, MnOOH was generated from the transformation of MnO2 during discharge, and the reaction between Ce3+ and MnOOH was beneficial for the reversibility of Ce4+, but also competitive with the disproportionation of MnOOH. As a result, Zn/MnO2 batteries with Ce(SO4)2 additives showed high capacity retention of 97.4% at 1.0 A g−1 after 1000 cycles, which far exceeded that of the batteries without Ce(SO4)2 (40.5%).