An ultralow-temperature aqueous zinc-ion battery

The freezing of aqueous electrolytes severely limits the operation of aqueous zinc-ion batteries (AZIBs) in low-temperature conditions owing to the terrible ion conductivity and interface kinetics. Here, a 4 M Zn(BF4)(2) electrolyte with a low freezing point (-122 degrees C) and high ion conductivity (1.47 mS cm(-1) at -70 degrees C) is developed for AZIBs. Comprehensive analyses, including spectroscopic measurement and theoretical calculation, demonstrate that introducing BF4- anions can break the hydrogen-bond networks in original water molecules by the formation of OHMIDLINE HORIZONTAL ELLIPSISF hydrogen bonds, resulting in an ultralow freezing point. The 4 M Zn(BF4)(2)-based electrolyte enables the Zn//tetrachlorobenzoquinone (TCBQ) battery to exhibit excellent electrochemical performance in the wide temperature range of 25 to -95 degrees C, achieving a high discharge capacity of 63.5 mA h g(-1) and energy density of 76.2 W h kg(-1) at a record-breaking temperature of -95 degrees C. This work provides a simple and green strategy to design high-performance AZIBs at low-temperature conditions.

Automated summary

A 4 M Zn(BF4)(2) electrolyte with low freezing point and high ion conductivity has been developed for aqueous zinc-ion batteries, enabling excellent electrochemical performance in a wide temperature range, including record-breaking performance at -95 degrees C. This work provides a simple and green strategy for designing high-performance AZIBs in low-temperature conditions.