Room-temperature sodium sulfur batteries (NaSBs) have developed as a promising energy solution for rising energy consumption due to their high theoretical capacity (1,675 mAh g-1) and cost-effectiveness. Yet, challenges such as soluble polysulfide migration, sodium dendrite formation and electrolyte leakage hinder their practical applications. This work addresses these limitations through integration of a gel polymer electrolyte (GPE) composed of high crosslinked polymer network through UV light in-situ polymerization of two individual monomers, tris[2-(acryloyloxy)ethyl] isocyanurate (THEICTA) and pentaerythritol tetraacrylate (PETA). The high crosslinked polymer matrix acts as both ion-conducting medium and physical separators, facilitating sodium ion movement while stabilizing sodium deposition. Furthermore, the GPE’s mechanical flexibility accommodates volume changes during cycling. The physicochemical properties of the GPE were examined through microscopic and spectroscopic analysis. Finally, GPE electrochemical evaluation reveals an ionic conductivity of 2.75mS cm-1 with a better plating/stripping performance at high current density compared to liquid electrolyte and an initial reversible specific capacity >500mAh g-1 at 0.1C with nearly 100% Coulombic efficiency after 200 cycles. This study demonstrates the designed GPEs enable high-capacity, dendrite-free NaSBs, offering a pathway towards next-generation energy storage systems.
