Anchoring and Competition: Weakly Solvated Structure of Glymes Enhances Stability in Lithium Metal Batteries Operating under Extreme Conditions

Lithium metal batteries (LMBs) face challenges from unstable and fragile solid electrolyte interphases (SEIs). In this work, we successfully develop a novel electrolyte by effectively modulating the competitive solvation process in LMBs. In this formulation, the C─O─C motifs of glymes are competitively substituted by other anions and solvents to achieve single oxygen site coordination, thereby facilitating a weak solvation effect. At an apparent concentration of 1.25 M, a solvated sheath enriched with anions and single oxygen-bound complexes is formed, which significantly enhances lithium metal compatibility and promotes rapid desolvation kinetics. The designed electrolyte using weakly solvated structures exhibits remarkable stability at both 25° and 80 °C, enabling the lithium iron phosphate (LFP)||Li cell to achieve over 2000 cycles (capacity retention: 90%) and 500 cycles (capacity retention: 96%), respectively. Interestingly, the low N/P ratio LFP||Li (N/P = 1.8) full battery maintains a stable capacity over 50 cycles, and the commercial 1.1 Ah LFP||Li pouch cell shows a great stability (capacity retention: 91.0%, CE: 99.82%) over 20 cycles. The distinctive solvation regulation strategy has paved a novel research avenue for the realization of high-performance LMBs.