Reducing Manganese Dissolution in Electrolytic Manganese Dioxide Electrodes in NaOH Electrolyte

Previous attempts to enhance the stability and performance of MnO 2 -based cathodes for use in aqueous alkaline electrolytes, primarily KOH-based, have relied on a range of additives. This work demonstrates that the fast capacity decay of the MnO 2 -based cathode materials in alkaline electrolytes is mainly due to spontaneous manganese dissolution when cycling through the second-electron reaction voltage range. Reducing relative electrolyte content and using carbon materials that have a high specific surface area suppresses manganese dissolution and thus extends the cycle life of the electrode material while reducing overall battery costs. Moreover, reducing the size of the MnO 2 particles and decreasing the cycling rate are found to increase manganese dissolution and negatively impact the performance of the electrode material, indicating a sensitivity to material surface area. Lastly, Fe-MnO 2 -based low-cost battery chemistry was also demonstrated based on the second electron reaction of the MnO 2 in an electrolyte lean environment, which could be promising for grid-level energy storage.