Qibang Pan, Shilin Zhang, Xiaoyu Gui, Jie Zhang, Wenbo Liu, Mingbao Huang, Zhiyong Fu*, Kai Wan*, Zhenxing Liang*
Solid polymer electrolytes (SPEs) are promising for lithium metal batteries due to their non-flammability and solid-state nature, though interfacial instability limits practical application. In this work, novel acrylate-based SPEs with carbonyl-modified polymer backbones are synthesized using either bis(2-(acryloyloxy)ethyl) heptanedioate (BAH) or bis(2-acryloyloxyethyl) malonate (BAM) monomers, in the presence of succinonitrile (SN) and lithium salts. The wider carbonyl spacing in PBAH (the BAH-derived SPE) results in a weaker interaction with Li⁺ ions than PBAM (the BAM-derived SPE). This weaker interaction favors anion-dominated solvation structures, facilitating the formation of LiF-enriched solid electrolyte interphase. The Li|PBAH|Li cell exhibits a high cyclability for 3500 h at 0.2 mA cm-2. Li|PBAH|LiFePO4 delivers 162 mAh g-1 at 0.1 C with 80.8% capacity retention after 2000 cycles at 1 C. Li|PBAH|LiNi0.8Co0.1Mn0.1O2 delivers 223 mAh g-1 at 0.1 C with 69.7% capacity retention over 200 cycles at 1 C. Anode-free Cu|PBAH|LiFePO4 achieves 153 mAh g-1 at 0.1 C and 90.80% capacity retention after 200 cycles at 0.5 C. The Li|PBAH|LiFePO4 pouch cell demonstrates its practical viability, exhibiting 161 mAh g-1 at 0.1 C and 80.7% capacity retention after 600 cycles at 1 C. This work offers a rational SPE design to enhance lithium metal battery performance and stability.