Morphological Evolution in Rechargeable Alkaline Zinc Anodes

Abstract

Dendrites, passivation, and shape changes are the common suspects to blame in the failures of rechargeable zinc anodes. The formation of porous zinc is not, or rarely discussed in the context of zinc batteries. We show that when starting with an electrode made of ZnO powder, the charging and then discharging cycles to a certain depth will make it partially a porous zinc electrode. This morphological evolution has important implications to the structural stability, as it reshapes the electronic conductivity, the specific area, the structural uniformity, and the geometrical path of the electrochemical reactions. By carefully dissecting some forty coin cells, we show step by step how the morphological evolution takes place and progresses, and how it may affect the cycle life.