Component Self-Initiated Photopolymerization for Gel Polymer Electrolytes in Zinc-Air Batteries.

Flexible zinc-air batteries (FZABs) require gel polymer electrolytes (GPEs) to ensure ionic transport, interfacial stability, and mechanical flexibility, yet their development is limited by trade-offs among mechanical robustness, low-temperature tolerance, and fabrication efficiency. Herein, a component self-initiated photopolymerization strategy is developed to achieve rapid gelation within minutes under visible-light irradiation without external initiators, providing an efficient route for fabricating high-performance GPEs. Within a proton-rich microenvironment, sodium citrate (SC) undergoes proton-coupled electron transfer to generate radicals that initiate the copolymerization of vinyl monomers within a sodium alginate (SA) matrix, forming a double-network hydrogel (AASx-SA). Additionally, SC induces network densification via the Hofmeister effect and modulates electrochemical properties, resulting in mechanically robust, dendrite-suppressing, and freeze-resistant GPEs. Consequently, the optimized AAS25-SA-GPE exhibits an ionic conductivity of 109 mS·cm-1 at -40°C and a freezing point of -69.1°C, enabling stable operation of the AAS25-SA-based FZAB for over 4220 cycles at -40°C. This work establishes an electrolyte design strategy in which a single electrolyte component integrates photoinitiation, structural construction, and electrochemical regulation, transforming electrolyte additives into active building blocks.