Carbonylation-tuned Li+ coordination enables enhanced ion transport kinetics in integrated cathode/polymer electrolytes

An integrated composite cathode with a programmable topological crosslinked polymer electrolyte (PTCPE) is fabricated via in-situ polymerization. • The programmable crosslinked network with tunable oxygen (ether)/oxygen (carbonyl) ratios can precisely regulate the Li + coordination structure. • The integrated LFP/PTCPE architecture with optimized carbonylation structure enables stable cycling at 0.5 C. Solid polymer electrolytes (SPEs) feature exceptional processability and interfacial compatibility for solid-state lithium metal batteries (SSLMBs). However, conventional polyether-based SPEs are still limited by sluggish ion transport kinetics arising from the strong Li + -ether oxygen (EO) coordination and high interfacial resistance toward the electrodes. Herein, an integrated cathode/polyether electrolyte is fabricated via in-situ copolymerization of poly(ethylene glycol) methyl ether acrylate (PEGMA) with a polycarbonate (PC)-based crosslinker. The resultant programmable topological crosslinked polymer electrolyte (PTCPE) contains carbonyl groups (-C=O) from PC segment that can weaken the Li + -EO coordination interaction in PEGMA matrix and reduce Li + transport barrier within the cathode/polymer electrolyte composite. By tuning the molecular weights of the PC crosslinker, the optimized spatial arrangement of -C=O and EO motifs can effectively reshape the Li + coordinated structure, thereby enabling low-energy barrier Li + transport pathways in the crosslinked structure. Consequently, the PTCPE electrolyte at an optimized PC molecular weight achieves an increased room-temperature ionic conductivity of 1.26×10 −4 S cm −1 , supporting the Li symmetric cell to cycle over 1400 h at 0.05 mA cm -2 . Furthermore, the integrated LiFePO 4 electrode/PTCPE electrolyte enables solid-state full cell to deliver a high initial specific capacity of 154.7 mAh g -1 at 1 C. This study highlights a strategy for tailoring Li + solvation environment to boost ionic conductivity, advancing practical applications of polyether-based SPEs in solid-state LMBs. An integrated cathode/polymer electrolyte with programmable topological crosslinked polyether-based electrolyte is proposed to enhance Li + transport kinetic within the polyether matrix via carbonylation crosslinking strategy. The precisely designed crosslinking density of the SPE enables controllable regulation of the Li + -O coordination configuration. Download: Download high-res image (471KB) Download: Download full-size image