Hybrid Solvent Coupled with Dual-Salt Electrolyte Enables High-Performance Lithium–Metal Batteries

Abstract

Lithium–metal batteries (LMBs) are widely recognized as the next-generation energy storage technology due to their high energy density, while their commercialization is hindered by the low Coulombic efficiency and uncontrolled Li dendrite growth. To address these challenges, an anion-rich solvation structure is achieved by a hybrid solvent coupled with a dual-salt electrolyte. The strongly coordinating DTA binds tightly to Li⁺ in the first solvation sheath, while the weakly coordinating FEC occupies the second solvation shell. Moreover, FEC, with a weak coordinating ability, allows TFSI^– and DFOB^– to enter the primary solvation sheath. The anion-derived SEIs exhibit enhanced mechanical strength and ionic conductivity, leading to accelerated Li⁺ transport kinetics and inhibited Li dendrite growth. As a result, the Li||Cu half-cell employing a hybrid solvent coupled with a dual-salt electrolyte delivers an average Aurbach Coulombic efficiency of 99.0%. Moreover, the Li||LiNi_0.8Co_0.1Mn_0.1O₂ battery exhibits robust capacity retention of 90.8% over 300 cycles, demonstrating the viability of hybrid solvent coupled with dual-salt electrolyte in practical LMBs.