Regulating interfacial reactions through electrolyte chemistry enables an anion-rich interphase for wide-temperature zinc metal batteries†

Zinc-ion batteries are challenged by zinc dendrites, notorious side reactions, and poor performance at low temperatures. Here, we present a dual-salt tuned electrolyte exhibiting a wide temperature range (−60 to 25 °C). The Zn(ClO₄)₂-based electrolyte with high hydrogen bond destruction ability and fast diffusion kinetics is suitable for application at ultralow temperatures. The introduction of Zn(OAc)₂ salt enhances cation–anion interaction and facilitates the formation of an anion-rich solvation shell and salt-derived interphase, overcoming issues caused by the strong oxidation of ClO₄⁻ in the presence of protons. The selective absorption of OAc⁻ on different zinc crystal planes favors dense zinc deposition towards (101) epitaxial while the as-formed anion-rich SEI layer, featuring 2ZnCO₃·3Zn(OH)₂ distributed on the surface and ZnCl₂ uniformly dispersed throughout, inhibits side reactions of corrosion and hydrogen evolution. Consequently, the batteries employing the designed electrolyte exhibited excellent performances, including a high Coulombic efficiency of 99.5% over 800 cycles at 25 °C; a near-unity Coulombic efficiency (100%) for over 4000 cycles and long cycling stability for over 5 months (16 500 cycles) in a Zn//I₂ battery with an accumulative capacity of 7300 mA h cm⁻² at −40 °C. Even at −60 °C, the solid-state electrolyte demonstrates practical applicability in Zn‖I₂/AC and Zn‖VO₂ batteries. This dual salt-tuned pure aqueous electrolyte also allows the reversible operation of a pouch cell for over 10 000 cycles with an accumulative capacity of 19.0 A h, indicating its promising potential for constructing safe and environmentally friendly zinc-ion batteries with broad working temperatures.