GAS EVOLUTION BEHAVIOR OF ZN ALLOY POWDER IN KOH SOLUTION

To reduce the mercury content in an alkaline manganese battery, a Zn alloy is used. In the absence or presence of small amounts of mercury, hydrogen gas evolution from the Zn alloy in KOH solution was found to be accelerated by the addition of ZnO or Zn(OH), which is the discharge product of Zn. Partly discharged Zn alloy also evolved hydrogen more vigorously compared to undischarged Zn alloy. An optimum quantity of In2O3 added to the Zn reduced hydrogen evolution. Indium metal deposited on Zn by the reduction of In2O3 by Zn will suppress hydrogen evolution because of its large overpotential for the hydrogen evolution reaction. Indium metal was detected by X-ray diffraction analysis of the Zn alloy containing In2O3.