Solid-state eutectic electrolyte via solvation regulation for voltage-elevated and deep-reversible Zn batteries

Solid-state electrolytes have the great potential to achieve high-voltage and durable zinc-based batteries, but their effectiveness is limited by inferior ionic conductivity and large interfacial voltage polarization. Here, a nonflammable solid-state eutectic electrolyte is prepared in situ by cross-linking polymerization of ternary eutectic electrolyte with ethoxylated trimethylpropane triacrylate. Thanks to the intermolecular interaction among the deep eutectic solvents and polymer skeleton, the solid-state eutectic electrolyte possesses satisfactory room-temperature ionic conductivity of 3.94 × 10-3 S cm-1. It enables the symmetric batteries with 80% Zn utilization operating stably at high current density of 8.0 mA cm-2 for 1700 h, exceeding all non-aqueous and most aqueous zinc batteries. More importantly, due to solvation structure regulation, the solid-state eutectic electrolyte is found to elevate discharge voltage plateau to 2.1 V in Zn full batteries, and presents favorable rate performance and cyclic stability at 25 $$\pm$$ ± 1 °C.