Extending temperature windows of practical zinc batteries by water-locking hydrated eutectic solvents

Aqueous zinc metal batteries have gained widespread attention in recent years due to their high safety and environmental friendliness. However, zinc metal anode still suffers from corrosion and hydrogen evolution reaction from the active water, and performances will be worse in high/low-temperature. Herein, a water-locking hydrated eutectic solvent (HES) electrolyte is developed for zinc metal batteries to solve the problem of poor temperature tolerance and low reversibility of Zn anode. BF4− anions and succinonitrile molecules are able to "lock" water molecules by hydrogen bond to inhibit water decomposition and zinc corrosion caused by water molecules. Therefore, the resulting aqueous zinc metal battery achieves continuous zinc plating/stripping for more than 2500 h, with an average Coulombic efficiency of up to 99.4 %, furthermore, it can stable cycle above 750 h at 60 °C and 3000 h at −25 °C. In addition, using the HES electrolyte, the 21700-type cylindrical battery assembled with gram class load vanadium-based cathode and limited supply of Zn anode shows excellent capacity and safety, and their assembled battery pack can show potential practical application prospects.