In Situ Crosslinking Polymerization and Redox Mediators for Gel‐Polymer Electrolyte‐Based Lithium‐Sulfur Batteries With Excellent Reaction Kinetics and Thermal Stability

ABSTRACT Lithium‐sulfur (Li‐S) batteries face critical challenges of lithium polysulfides (LiPSs) shuttling and lithium dendrites in liquid electrolytes, while conventional gel polymer electrolytes (GPE) suffer from low thermal stability (<110°C) and sluggish kinetics. This work pioneers a dual‐function modification strategy integrating in situ cross‐linking polymerization and a redox mediator for GPE‐based Li‐S batteries. A novel TMPDOL copolymer electrolyte is designed through selective crosslinking of trihydroxymethylpropane tris[3‐(2‐methyl‐1‐aza‐cyclobutyane)propionate] (TMP) with 3‐dioxopentane (DOL), achieving record thermal stability (392°C decomposition temperature), and it can also promote the dissociation of LiTFSI and accelerate lithium‐ion transport kinetics. Concurrently, the SnF 2 initiator generates a LiF/Li 13 Sn 5 ‐rich solid electrolyte interphase (SEI) enabling uniform lithium deposition, while the 2‐ethylanthraquinone (2‐EAQ) redox mediator catalytically accelerates polysulfide conversion kinetics and inhibits the shuttle of LiPSs. The Li‐S batteries exhibit a promising discharge specific capacity of 718 mAh g −1 at 3 C and excellent long‐term cycling stability over 500 cycles at 1 C. This work introduces new electrolyte engineering paradigms through molecular crosslinking for thermal resilience, dynamic redox mediation to overcome kinetics barriers, and multi‐functional initiators for stable interfaces, providing a scalable pathway for the development of GPE‐based Li‐S batteries with high dynamic, excellent thermal stability and safety.