Modelling and Simulation of Zinc-Air Batteries with Aqueous Electrolytes

Abstract

Primary zinc-air batteries have long been an industry standard for low-power applications like hearing aids. Their high theoretical specific energy (1086 Wh ∙ kg-1), use of cheap and non-hazardous materials, and superior operational safety make secondary zinc-air batteries desirable for emerging markets such as electric vehicles or grid storage. But effects including poor cycling stability of the anode, carbonate formation in the alkaline electrolyte, and the lack of a suitable bi-functional air catalyst have limited their use. The Horizon 2020 project Zinc Air Secondary (ZAS!) aims to develop a high-performance rechargeable zinc-air battery capable of achieving more than 1000 cycles. Modelling and simulation of novel cell materials and architectures provides crucial support towards achieving this goal. We have developed a 1D finite volume continuum model implemented in MATLAB. Our model includes a thermodynamically consistent description of mass transport in concentrated ternary electrolytes, multi-phase coexistence in porous media, and reaction kinetics with considerations for anode passivation due to types I and II ZnO, among other effects. Within this framework, we simulate cell performance and lifetime considering various material com-positions and cell architectures. Initial results show that inhomogeneous Zn dissolution and ZnO precipitation in 32 wt% KOH may lead to significant mass transport limitations, particularly at higher current densi-ties. Furthermore, under certain operating conditions type II ZnO may form on the zinc elec-trode surface, permanently shutting down the cell. To address these issues and improve overall performance the effects