Understanding the degradation process in zinc-iodine hybrid flow batteries

This dataset contains all measurements collected during the investigation of the degradation phenomenon known as the voltaic bulge, observed in zinc-iodine hybrid flow batteries (ZIHFBs). The voltaic bulge is characterized by a sharp increase in charging voltage followed by a sudden drop, and its presence correlates with a decline in battery performance. To understand the origin of this phenomenon and identify safe operating conditions, the study employed various electrochemical techniques, including galvanostatic cycling, combined galvanostatic and potentiostatic cycling, and electrochemical impedance spectroscopy (EIS) in both potentio (PEISOCV) and galvano (GEISLOAD) modes. Additionally, various single-cell construction modifications were implemented to deepen our understanding of the phenomenon. These included the use of non-conductive felt (NCF) in combination with graphite felt (GF), and the connection of electrolyte tanks via a thin capillary referred to as a hydraulic shunt (HS). Furthermore, the study explored the effects of different electrolyte compositions, such as omitting ZnI₂ from the posolyte and increasing the concentration of tri-iodide ions in the posolyte. The findings presented in this manuscript provide insights into the mechanisms behind the voltaic bulge and offer guidelines for optimizing ZIHFB operation to mitigate its impact.