Progress in Electrolyte Engineering of Aqueous Batteries in a Wide Temperature Range

Aqueous rechargeable batteries are safe and environmentally friendly and can be made at a low cost; as such, they are attracting attention in the field of energy storage. However, the temperature sensitivity of aqueous batteries hinders their practical application. The solvent water freezes at low temperatures, and there is a reduction in ionic conductivity, whereas it evaporates rapidly at high temperatures, which causes increased side reactions. This review discusses recent progress in improving the performance of aqueous batteries, mainly with respect to electrolyte engineering and the associated strategies employed to achieve such improvements over a wide temperature domain. The review focuses on five electrolyte engineering (aqueous high-concentration electrolytes, organic electrolytes, quasi-solid/solid electrolytes, hybrid electrolytes, and eutectic electrolytes) and investigates the mechanisms involved in reducing the solidification point and boiling point of the electrolyte and enhancing the extreme-temperature electrochemical performance. Finally, the prospect of further improving the wide temperature range performance of aqueous rechargeable batteries is presented.