An insight into the self-discharge of Fe3O4 electrodes in alkali solutions

Abstract

Iron oxide development is necessary as the Iron electrodes exhibit high self discharge and poor charging efficiency in alkaline batteries. Pressed electrodes containing electrolytic iron powder with varying amounts of Fe3O4 have been used. The variation of open circuit potential and self discharge currents with alkali concentration is followed. For better understanding of these variations, cyclic polarisation (−1.3 V to + 0.4 Vvs Hg/HgO) and hydrogen evolution studies are carried out. Beyond −0.5 Vvs Hg/HgO, the surface is covered by hydrolysed layer and the protons diffuse away from this layer. The hydrogen evolution takes place with the discharge of K+ ions as the rate determining step.