The Cathodic Reduction Mechanism of Electrolytic Manganese Dioxide in Alkaline Electrolyte

Constant‐current discharge curves for electrodeposited on graphite showed a two‐stage reduction; to and to . Potential decreased continuously during the first stage and in some discharges was constant for at least half of the second. The first stage was not influenced by current density, concentration, thickness, or a complexing agent. The constant‐potential portion was observed with , low current density; the potential was near the standard redox potential of Mn(II) and Mn(III) species in solution as determined polarographically. The first stage is considered a homogeneous phase reduction, while the second stage involves a heterogeneous system. A new mechanism is suggested for the latter.