Decoordination-enabled dynamic Lewis acid regulation in poly (ethylene oxide) solid polymer electrolytes for high-performance all-solid-state lithium metal batteries

Poly(ethylene oxide) (PEO)-based solid polymer electrolytes have long been attractive for all-solid-state lithium metal batteries owing to their processability and interfacial conformity. However, their application is limited by sluggish ion transport and insufficient electrochemical stability. Here, we propose a dynamic Lewis acid regulation strategy by incorporating aluminum acetylacetonate (AlACA) into PEO. Partial decoordination of AlACA exposes Lewis-acidic Al 3+ centers that coordinate with EO segments and TFSI ⁻ anions, simultaneously tuning ion transport and interfacial chemistry. This interaction reconfigures local Li + solvation and polymer networks, weakens EO–Li⁺ coordination, promotes salt dissociation, and suppresses crystallization, resulting in an order-of-magnitude higher room-temperature ionic conductivity. Meanwhile, Lewis-acid-mediated anion regulation induces a LiF-rich interphase, mitigating parasitic reactions and dendrite growth and extending electrochemical stability to 4.8 V. The regulated PEO electrolyte enables Li||LiFePO 4 cells to cycle over 1000 times, and Li||LiMn 0.6 Fe 0.4 PO 4 cells to sustain 340 cycles at 2C (3.0–4.35 V) with 80% capacity retention. A stack-pressure-free pouch cell retains 85.3% capacity after 200 cycles. When coated onto PE separators through a standard coating process, the ultrathin (13 μm) PEO electrolyte exhibits high mechanical strength (59.9 MPa). This work establishes decoordinated Lewis acid regulation as a molecular design strategy to advance high-performance, application-oriented PEO-based SPEs.