Bonding interaction regulation in hydrogel electrolyte enable dendrite-free aqueous zinc-ion batteries from −20 to 60 °C

Aqueous zinc-ion batteries are promising energy storage devices due to their safety and abundant resources. However, the leakage, dendrites, and poor performance at high and low temperatures seriously limit the practical application. Hydrogel electrolyte with plenty of water and high flexibility is an ideal candidate for the liquid electrolyte. Here, we present a functional gel electrolyte composed of polyacrylamide (PAM), ZnSO4 (ZS), glycerol (GL), and acetonitrile (AN) with excellent mechanical properties, high ionic conductivity, and modulated bonding interaction. FTIR and DFT calculations show that the water activity is extremely decreased and the bonding interaction in this system is adjusted owing to the affinity between H2O/Zn2+ and oxygen-containing groups in the hydrogel, leading to the uniform Zn deposition, high stability, and wide operating temperature range (−20 ∼ 60 °C). The batteries with gel electrolyte exhibit high cycling stability (Zn//Zn battery steadily cycles over 3000 h), high reversibility (Coulombic efficiency reaches 99.5%), and enhanced electrochemical performance (185 mAh·g−1 at 5 A·g−1 over 10,000 cycles). Even at −20 °C and 60 °C, the batteries show excellent cycling stability (Zn//Zn battery cycles over 500 h) and high capacity performance.