In-Operando X-Ray Imaging for Sobering Examination of Aqueous Zinc Metal Batteries

Aqueous zinc metal batteries (AZMBs) face significant challenges in achieving reversibility and cycling stability, primarily due to hydrogen evolution reactions (HER) and zinc dendrite growth. In this study, by employing carefully designed cells that approximate the structural characteristics of practical batteries, we revisit this widely held view through in-operando X-ray radiography to examine zinc dendrite formation and HER under near-practical operating conditions. While conventional understanding emphasizes the severity of these processes, our findings suggest that zinc dendrites and HER are noticeably less pronounced in dense, real-operation configurations compared to modified cells, possibly due to a more uniform electric field and the suppression of triple-phase boundaries. This study indicates that other components, such as degradation at the cathode current collector interface and configuration mismatches within the full cell, may also represent important barriers to the practical application of AZMBs, particularly during the early stages of electrodeposition.