Carbonyl‐Engineered Acrylate‐Based Solid Polymer Electrolyte for High‐Performance Lithium Metal Batteries

Abstract 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 and lithium salts. The wider carbonyl spacing in the BAH‐derived SPE (PBAH) results in a weaker interaction with Li⁺ ions than the BAM‐derived SPE (PBAM). 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|LiFePO ₄ delivers 162 mAh g ⁻¹ at 0.1 C with 80.8% capacity retention after 2000 cycles at 1 C. Li|PBAH|LiNi _0.8 Co _0.1 Mn _0.1 O ₂ delivers 223 mAh g ⁻¹ at 0.1 C with 69.7% capacity retention over 200 cycles at 1 C. Anode‐free Cu|PBAH|LiFePO ₄ achieves 153 mAh g ⁻¹ at 0.1 C and 90.80% capacity retention after 200 cycles at 0.5 C. The Li|PBAH|LiFePO ₄ 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 capacity and stability.