Modeling Nucleation and Growth of Zinc Oxide During Discharge of Primary Zinc-Air Batteries

TL;DR

This paper develops a comprehensive continuum model for zinc-air batteries, capturing zinc dissolution, zinc oxide nucleation and growth, electrolyte transport, and gas phase interactions, validated by experiments, to improve understanding of battery discharge and lifetime.

Contribution

It introduces a thermodynamically consistent model of zinc-air battery discharge that includes zinc oxide nucleation and growth, validated with experimental data, offering insights for rechargeable zinc-air battery development.

Findings

Model accurately predicts zinc-air battery discharge behavior.

Zinc oxide nucleation and growth significantly impact battery lifetime.

Insights into electrolyte and gas phase interactions inform battery design.

Abstract

Metal-air batteries are among the most promising next-generation energy storage devices. Relying on abundant materials and offering high energy densities, potential applications lie in the fields of electro-mobility, portable electronics, and stationary grid applications. Now, research on secondary zinc-air batteries is revived, which are commercialized as primary hearing aid batteries. One of the main obstacles for making zinc-air batteries rechargeable is their poor lifetime due to the degradation of alkaline electrolyte in contact with atmospheric carbon dioxide. In this article, we present a continuum theory of a commercial Varta PowerOne button cell. Our model contains dissolution of zinc and nucleation and growth of zinc oxide in the anode, thermodynamically consistent electrolyte transport in porous media, and multi-phase coexistance in the gas diffusion electrode. We perform electrochemical measurements and validate our model. Excellent agreement between theory and experiment is found and novel insights into the role of zinc oxide nucleation and growth and carbon dioxide dissolution for discharge and lifetime is presented. We demonstrate the implications of our work for the development of rechargeable zinc-air batteries.