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

The zinc-ion batteries are challenged by zinc dendrite, notorious side reactions, and poor performance at low temperatures. Here, we present a dual-salts tuned electrolyte exhibiting a wide temperature range (-60 to 25 ºC). The Zn(ClO4)2-based electrolyte with high hydrogen bond destruction ability and fast diffusion kinetics favors the application at ultralow temperatures. The introduction of Zn(OAc)2 salt enhances cation-anion interaction, and facilitates the formation of anion-rich solvation shell and salt-derived interphase, conquering issues caused by the strong oxidation of ClO4- in the presence of protons. The absorbed OAc- on the zinc surface 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 designed electrolyte contributed to excellent performances, including a high Coulombic efficiency of 99.5% over 800 cycles at 25 ºC; a near-unity Coulombic efficiency (100%) for over 4,000 cycles and long cycling stability for over 5 months (16,500 cycles) in Zn//I2 battery with an accumulative capacity of 7,300 mAh cm-2 at -40 ºC. Even at -60 ºC, 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 Ah, indicating its promising potential for constructing safe and environmentally friendly zinc-ion batteries with broad working temperatures.