《Anion-Regulated Weakly Solvating Electrolytes for High-Voltage Lithium Metal Batteries》

The development of new high-voltage electrolytes is the key to achieving high energy density lithium metal batteries. Previous studies have shown that a weakly solvated electrolyte can produce a unique anion-driven interface chemistry by changing the solvation capacity of the solvation, but it can only dissolve part of the lithium salt and cannot cycle stably at cut-off voltages above 4.5 V. Therefore, we propose a novel anionically regulated weak solvated electrolyte, and for the first time realize the stable cycling of conventional lithium salt concentration ether electrolyte at 4.6 V. In this work, we systematically studied the relationship between salt dissociation, electrolyte solvation structure and electrochemical performance of lithium metal batteries, and found that LiBF4, with the lowest degree of dissociation, can form anion-rich solvated sheaths, resulting in an anion-derived interface. Thanks to this unique solvation structure and interfacial chemistry, the electrolyte enables stable cycling of Li-LiCoO2 full cells under practical conditions at a cut-off voltage of 4.6 V.

https://doi.org/10.1002/eem2.12440