Operando Characterization of Zinc Metal Batteries—Probing Zinc Sulfate Hydroxide Formation and Zinc Crystallographic Orientation with X-Ray Diffraction

Zinc-based batteries are emerging as a promising alternative to lithium-ion technologies, underscoring the need to understand zinc plating behavior and its effects on battery performance. In this study, operando X-ray diffraction (XRD) was used to investigate zinc metal batteries utilizing a ZnSO₄ electrolyte, the most common electrolyte in zinc battery systems. By varying current density and capacity, we examined the formation of zinc hydroxide sulfate (ZHS), the efficacy of zinc plating, and the crystallographic orientation of zinc during cycling. We quantified the relative amounts of ZHS and zinc metal, providing insights into capacity losses attributed to hydrogen evolution versus dead zinc formation. These results were compared to our findings using acetonitrile as an electrolyte additive, offering further understanding of how electrolyte modifications influence zinc deposition and ZHS suppression. These insights contribute to optimizing zinc metal battery performance and advancing their potential for large-scale energy storage applications beyond lithium-ion technologies.