Regulating zinc nucleation and growth with low-surface-tension electrolytes for practical aqueous zinc metal batteries

Rechargeable zinc metal batteries are promising for large-scale energy storage due to their low cost and high safety, but their development is seriously hindered by the dendritic growth and side reactions of zinc metal anodes. To address this challenge, we report here that rational design of low-surface-tension electrolytes can enable dense nucleation and fine-grained growth of zinc. This low-surface-tension strategy leads to high stability of the solid-electrolyte interface, dendrite-free morphology and suppressed side reactions. Therefore, zinc metal anodes achieve a high average Coulombic efficiency of 99.72% over a lifespan of 8400 hours at 1 mA cm^-2/1 mAh cm^-2. Even at harsh electrochemical conditions of 10 mA cm^-2/10 mAh cm^-2, the lifespans of zinc metal anodes exceed 2200 and 300 hours at 17% and 85% depth of discharge, respectively-over 20-fold and 150-fold improvements compared with those using conventional electrolytes (2 mol kg^-1 zinc trifluoromethanesulfonate with 1.5 wt% zinc acetate dihydrate). A 1.27 Ah pouch cell is demonstrated to showcase the practicability of this strategy. This work uncovers the critical role of electrolyte's surface tension for advanced zinc metal anodes, and offers a potentially cost-effective and sustainable pathway toward commercially viable rechargeable zinc metal batteries.