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 (AAS x ‐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.