Strongly Solvating Ether Electrolytes for High-Voltage Lithium Metal Batteries

Ethers are promising electrolytes for lithium (Li) metal batteries (LMBs) because of their unique stability with Li metal. Although intensive research on designing anion-enriched electrolyte solvation structures has greatly improved their electrochemical stabilities, ether electrolytes are approaching an anodic bottleneck. Herein, we reveal the strong correlation between electrolyte solvation structure and oxidation stability. In contrast to previous designs of weakly solvating solvents for enhanced anion reactivities, the triglyme (G3)-based electrolyte with the largest Li⁺ solvation energy among different linear ethers demonstrates greatly improved stability on Ni-rich cathodes under an ultrahigh voltage of 4.7 V (93% capacity retention after 100 cycles). Ether electrolytes with a stronger Li⁺ solvating ability could greatly suppress deleterious oxidation side reactions by decreasing the lifetime of free labile ether molecules. This study provides critical insights into the dynamics of the solvation structure and its significant influence on the interfacial stability for future development of high-efficiency electrolytes for high-energy-density LMBs.