Halozincate ionic liquid electrolyte enabled high-temperature dendrite-free Zn metal batteries†

Aqueous Zn metal batteries (ZMBs) are receiving increasing attention due to their safety, cost-effectiveness, and scalability. However, aqueous ZMBs suffer from the hydrogen evolution reaction (HER), dendrite growth, and intrinsic volatility of electrolytes at high temperatures, hindering their practical application in mining/drilling, industrial manufacturing, and aerospace. Here, we introduce an anhydrous electrolyte design by using halozincate ionic liquid electrolyte (HZLE) to achieve dendrite-free Zn anode chemistry and facilitate high-temperature ZMBs. The halozincate solvation structure in HZLE pulls out a coordination channel for fast Zn²⁺ transport and enables high reversible deposition/dissolution of the Zn anode. The Zn‖Ti cells show uniform Zn deposition with an average Zn plating/stripping Coulombic efficiency (CE) of 99.99%. As a result, Na₃V₂(PO₄)₃‖Zn batteries exhibit high CE exceeding 99.81% at 25 °C and can sustain 1000 deep cycles at 80 °C. This HZLE design offers an opportunity for alkali–metal–ion batteries to operate at high temperatures.