Crosslinking Temperature-Regulated Topological Confinement of Amorphous PEO Electrolytes for High-Performance Sodium-Metal Batteries

Poly(ethylene oxide) (PEO) is a promising solid-state polymer electrolyte (SPE), but its room-temperature crystallization leads to low ionic conductivity, limiting its application. Semi-interpenetrating networks (semi-IPNs) represent an effective strategy for suppressing PEO crystallization. Previous studies have overlooked the influence of crosslinking temperature on the network topology. Here, we report a crosslinking temperature-regulated topological confinement of amorphous PEO electrolyte achieved by initiating the photopolymerization of ethoxylated trimethylolpropane triacrylate (ETPTA) at 80 °C. The resulting homogeneous network effectively confines the amorphous phase of PEO while retaining local freedom for Na+ transport. When the mass ratio of PEO to ETPTA is 60:40 (P-E40H), the material exhibits optimal comprehensive electrochemical performance, demonstrating a high room-temperature ionic conductivity of 0.173 mS cm-1, a high Na+ transference number of 0.59, high voltage stability of 4.72 V, and an elongation at break of 160.05%. Molecular dynamics simulations indicate that the uniform network allows Na+ to adopt a solvation structure dominated purely by PEO. The capacity retention ratios of Na3V2(PO4)3|P-E40H|Na cell are 92.9% (1 C, 400 cycles) and exhibits a specific capacity of 64.05 mAh g-1 at 5 C. This work demonstrates that crosslinking temperature is an effective processing parameter for tuning the network topology of semi-IPN electrolytes, offering a simple and efficient structural regulation strategy for high-performance solid-state sodium-metal batteries.