Operando Monitoring of Rechargeable Zinc-Air Batteries with Acoustic Emission

This study demonstrates that the acoustic emission (AE) methodology can be successfully applied to zinc-air battery systems. AE analysis provides real-time insights into mechanically induced events and enables qualitative correlation with electrochemical processes during different operating stages. The method shows high sensitivity to corrosion-driven hydrogen evolution under open-circuit conditions and to oxygen-evolution-related activity in catalyst-based gas diffusion electrodes during charging. In commercial cells, a pronounced increase in AE activity once the cell voltage exceeds 1.8 V indicates the onset of carbon-related degradation, while final AE spikes prior to failure reflect the mechanical manifestation of critical degradation events such as separator rupture or electrode collapse. Overall, the results highlight AE as a powerful diagnostic tool for identifying mechanically driven degradation phenomena in metal–air batteries. Consideration of the observed diffusion limitations and the future implementation of advanced analysis tools, including distribution of relaxation times, equivalent circuit models, and machine-learning approaches, will further refine the understanding of process contributions in next-generation rechargeable battery systems.