Investigating Degradation Modes in Zn‐AgO Aqueous Batteries with In Situ X‐Ray Micro Computed Tomography

Abstract To meet growing energy demands, degradation mechanisms of energy storage devices must be better understood. As a non‐destructive tool, X‐ray Computed Tomography (CT) has been increasingly used by the battery community to perform in situ experiments that can investigate dynamic phenomena. However, few have used X‐ray CT to study representative battery systems over long cycle lifetimes (>100 cycles). Here, the in situ CT study of Zn–Ag batteries is reported and the effects of current collector parasitic gassing over long‐term storage and cycling are demonstrated. Performance representative in situ CT cells are designed that can achieve >250 cycles at a high areal capacity of 12.5 mAh cm⁻². Combined with electrochemical experiments, the effects of current collector parasitic gassing are revealed with micro‐scale CT. The volume expansion and evolution of ZnO and Zn depletion are quantified with cycling and elevated temperature testing. The experimental insights are utilized to develop larger form‐factor (4 cm²) cells with electrochemically compatible current collectors. With this, over 500 cycles at a high capacity of 12.5 mAh cm⁻² for a 4 cm² form‐factor are demonstrated. This work demonstrates that in situ X‐ray CT used in long cycle‐lifetime studies can be applied to examine a multitude of battery chemistries to improve performances.