Atomic and Molecular Structure Regulated In Situ Cross-Linked Polyurethane Gel Electrolyte for High-Performance Lithium Metal Batteries

Abstract The incompatibility of conventional electrolytes with high-voltage cathodes and lithium metal anodes limits the performance of lithium metal batteries (LMBs). Here, an in situ cross-linked polyurethane gel electrolyte (G-P3 AR) is designed through atomic and molecular structure regulation. The polyester segments widen the highest occupied molecular orbital–lowest unoccupied molecular orbital gap, extending the electrochemical stability window to 4.97 V for compatibility with NCM811 cathodes. Polyether segments exhibit a lower Li + binding energy, reducing the desolvation barrier and enhancing anode stability. At the atomic level, sp 2 -hybridized boron in the chain extender immobilizes anions (TFSI − and DFOB − ) through Lewis acid–base interactions, raising the Li + transference number to 0.78 and enabling exceptional rate capability (157.7 mAh g −1 at 2 C in the Li||NCM811 cell). Hydrogen bonding between the polymer and solvent restructures the solvation sheath, promoting inorganic-rich interphases. The Li|G-P3 AR|NCM811 cell retains 81.7% capacity after 500 cycles at 0.5 C charge/1 C discharge, demonstrating a rational electrolyte design strategy for high-performance LMBs.