Solvation-Regulated Ultrafast Formation of Organohydrogel Electrolytes for Subzero Flexible Zinc-Ion Batteries

The scalable fabrication of covalently cross-linked hydrogel electrolytes is often constrained by the energy-intensive nature of conventional initiation methods, which rely on heat or ultraviolet irradiation. Such approaches not only consume significant energy but also provide limited control over polymer network formation, frequently necessitating additional co-solvents or additives to meet mechanical and electrochemical requirements. Herein, we present a solvation regulation strategy that decouples radical polymerization from external energy inputs through solvation-state engineering of the precursor, enabling the rapid (<1 min), spontaneous formation of a polyacrylamide organohydrogel at room temperature. Mechanistically, Zn²⁺ and BF₄ ^- synergistically reduce the activation barrier for initiator dissociation, while formamide acts as a dynamic solvation shield, suppressing water-induced radical quenching. This solvation-state adjustment also modifies the hydrogen-bonding network, lowers the freezing point to -54°C and enhances mechanical robustness. The optimized microenvironment further mitigates parasitic reactions and zinc dendrite formation. As a result, symmetric Zn||Zn cells maintain stable cycling for over 10 000 h at -40°C, while flexible Zn/polyaniline full cells retain reversible capacity over 1000 cycles and exhibit stable performance under repeated mechanical deformation at -40°C. This work demonstrates an energy-efficient, scalable strategy for producing gel electrolytes suitable for aqueous energy storage under extreme conditions.