The Anodic Oxidation of Manganese Oxides in Alkaline Electrolytes

Manganese dioxide electrodes are discharged in electrolytes of 1 M to 10 M KOH and immediately reoxidized anodically. The efficiency of the oxidation, determined by chemical analysis as well as subsequent cathodic reduction, is a function of the concentration of KOH and decreases as the KOH concentration increases from 1 M to 10 M KOH . In 1 M KOH , MnO 2 is reduced to a species tentatively identified as an active form of manganese (III) oxide, which can be efficiently reoxidized to MnO 2 . In 10 M KOH , however, MnO 2 is reduced first to manganese (III) oxide and subsequently to manganese (II) oxide. This manganese (II) oxide can be recharged only to an inactive form of manganese (III) oxide which is not reoxidized efficiently to MnO 2 .