(Invited) Zinc Surface Morphological Variations and Ionic Mass Transfer Rates in Alkaline Solution

Abstract

A horizontal upward-facing Zn anode was electrochemically dissolved in aqueous alkaline electrolyte. A plane-parallel upwardfacing Ni(OH) 2 /NiOOH cathode was combined with this Zn anode in a single cell, divided by a polymer separator. This configuration can be considered as a model single pore inside the mesoporous space of a Zn-NiOOH battery cell. It also insures that ionic mass transfer by diffusion and migration is dominant over that by natural convection. The morphological variations of the Zn anode surface plane were examined during the discharge operation of the ZnNiOOH model cell. The two-dimensional transient concentration profiles of each ion accompanying the electrochemical dissolution of Zn anode in the alkaline electrolyte were numerically calculated. The surface morphological variations of the Zn anode were discussed with the aid of numerical simulation. ZnO precipitation on the Zn anode surface was confirmed to be dependent on the horizontal distance from the cell separator. The numerical model provides insight to the analysis of observed morphological variations along the anode surface.