Aqueous Zinc‐Ion Batteries with Boosted Stability and Kinetics under a Wide Temperature Range

Abstract Sustainable aqueous zinc ion batteries (AZIBs) necessitate a wide operational temperature range to ensure practicability, yet achieving this often compromises either reaction kinetics at low temperatures or cycling stability at high temperatures. Here we present an electrolyte design that balances this trade‐off, enhancing the stability and kinetics of AZIBs across −60 to 60 °C. Our approach incorporates silk fibroin as a multifunctional additive into ZnCl 2 ‐based “water‐in‐salt” electrolyte, which modifies both electrolyte structure and electrode interphase. Specifically, Zn||Zn half‐cells with this electrolyte realize low hysteresis (180 mV at 1 mA cm −2 ) at −60 °C, and stable operation (200 hours at 2 mA cm −2 ) at 60 °C. This electrolyte is compatible with both inorganic and organic cathode materials. Remarkably, an ampere‐hour‐level Zn||V 2 O 5 ⋅ n H 2 O pouch cell with this electrolyte achieves an energy density of ∼72 W h L −1 with minimal capacity decay after 50 cycles at 0.5 A g −1 . Furthermore, the pouch cell stably cycles across −60 to 60 °C. This strategy provides a powerful solution to the challenges of aqueous metal‐ion batteries at extreme temperatures.