In Situ Rapid-Photocured Hydrated Eutectogels for Uniform Zn Plating and Stable Anode in Flexible Zinc-Ion Batteries

Eutectogels have emerged as promising gel electrolytes for zinc-ion batteries (ZIBs), addressing critical issues such as dendrite growth, parasitic reactions, and safety concerns, which are limited in conventional hydrogels and organogels. Here, we report hydrated eutectogel electrolytes (HETEs) composed of methacryloylcholine chloride, ethylene glycol, and zinc acetate, synthesized via a one-pot rapid-UV curing process under ambient conditions. The optimal HETE-15H₂O formulation achieves excellent mechanical resilience and a broad electrochemical stability window (2.31 V). The inclusion of 15 wt.% water enhances ionic conductivity while suppressing water-induced hydrogen evolution and dendrite formation. Grazing incidence X-ray absorption spectroscopy (GI-XAS) and molecular dynamics simulations reveal distinct Zn solvation structures correlating with stable Zn plating/stripping. The Zn||Zn cell exhibits over 8000 h cycle life, while the Zn||PANI full cell delivers comparatively high energy and power densities relative to previously reported eutectogel-based ZIBs and retains 85% capacity after 1000 cycles at 1 A g^-1. These findings emphasize the possible use of HETEs for safe, durable, and flexible Zn-ion batteries.