Fatty acid methyl ester ethoxylate additive for enhancing high-temperature aqueous zinc-ion battery performance

Aqueous zinc-ion batteries (AZIBs) have attracted significant attention due to their high theoretical capacity, low cost, and excellent safety. Nevertheless, their practical applications are hindered by challenges such as electrolyte decomposition, Zn corrosion/passivation, and dendrite growth, which become more severe under high-temperature conditions. To address these issues, innovative electrolyte design has become a key strategy. In this study, we propose a simple and effective electrolyte modification strategy by introducing fatty acid methyl ester ethoxylate (FMEE) as an additive. FMEE functions as both a solvation structure regulator and a water cluster stabilizer, effectively suppressing side reactions and promoting the formation of a robust solid electrolyte interphase enriched with ZnS and ZnF2. This significantly improves the interfacial chemical stability of the Zn anode. As a result, the Zn anode achieves an extended cycling lifespan of up to 3000 h at 1 mA cm−2 and 1 mAh cm−2. Furthermore, the Zn–V2O5 full cell using the FMEE-modified electrolyte exhibits an excellent rate performance and long-term cycling stability. Notably, the cell maintains a superior electrochemical performance even at 60 °C, demonstrating remarkable thermal stability. This study offers a new strategy for developing high-performance, temperature-tolerant AZIBs.