Temperature-dependence of Zn deposition/stripping behavior in aqueous Zn-based flow batteries

A thorough understanding of the growth behaviors of Zn anode at various temperatures is essential for improving the lifespan of Zn-based flow batteries (ZFBs). However, the impact of temperature on Zn deposition in ZFBs has not been thoroughly investigated. In this work, we find that at low temperatures (0–40 °C) Zn deposit presents a dense and smooth morphology with minimal side reactions, such as hydrogen evolution and aqueous corrosion. Above 60 °C, Zn begins to grow vertically on the substrate, forming larger particles and intensifying side reactions. These differences in Zn growth behaviors at varying temperatures are closely linked to changes in Zn nucleation, as observed through in situ atomic force microscopy. Consequently, elevated temperature in a ZFB promotes preferentially vertical deposition of Zn at the membrane/electrode interface, extending into the membrane. As a result, this significantly hinders ion transport across the membrane and substantially increases the risk of short-circuiting. This process is the primary factor contributing to the reduced lifespan of ZFBs at high temperatures.