Tailored Stereo‐Configuration of Crosslinkable Polyester‐Based Solid Polymer Electrolytes for All‐Solid‐State and Binder‐Free Li Metal Batteries

ABSTRACT By harnessing stereoisomerism in unsaturated polyesters, we elucidate how subtle structural variations impact Li + solvation structures by modulating free volume, Li + diffusivity, and lithium salt dissociation within solid polymer electrolytes (SPEs). The intrinsic reactivity of C═C bonds along the polymeric backbones is further exploited via a facile UV‐curing approach to construct robust three‐dimensional polymeric networks that impart mechanical robustness and preferential restriction of TFSI − mobility relative to Li + transport. The distorted conformation of poly( n ‐pentyl maleate) (PPM) leads to sparsely crosslinked structures, preserving efficient Li + transport pathways. Furthermore, end‐group fluorination enhances interfacial stability by facilitating the formation of a LiF‐rich solid electrolyte interphase. These synergistic design strategies culminate in a crosslinked PPM‐based SPE (XL‐PPM‐3F‐Li) featuring one CF 3 end‐capping group, which exhibits remarkable electrochemical durability in both Li||Li symmetric and LFP full‐cell configurations. Furthermore, this advantage is extended to the device level by integrating binder, electrolyte, and separator into a single ultrathin (∼“5 µm‐thick”) crosslinked SPE that conformally interfaces with the electrode microstructure. This integrated configuration markedly lowers interfacial and charge‐transfer resistance, enabling 65% of the initial reversible capacity at 2 C and 93.6% retention after 100 cycles at 0.5 C (60°C). Overall, this crosslinking‐enabled unified architecture establishes a robust strategy for ultra‐stable solid‐state lithium‐metal batteries.