A Hybrid Solvating Electrolytes Strategy for Rapid Li⁺ Desolvation and High Ionic Conductivity Enabling Fast-Charging...

The development of fast-charging lithium metal batteries (LMBs) is hindered by uncontrolled Li dendrite growth, unstable solid electrolyte interphase (SEI), and sluggish desolvation kinetics. Herein, we present a rational molecular design strategy for hybrid solvating electrolytes (HSEs) that integrates a weakly solvating sulfonamide (N, N-dimethyl(trifluoromethanesulfonyl)amide, DMTMSA) with a strongly solvating fluoroethylene carbonate (FEC) and a dual-salt system (LiTFSI/LiDFOB). Unlike conventional single-solvent systems, this unique combination creates an anion-dominated primary solvation sheath, which thermodynamically weakens the Li^+-solvent binding and kinetically reduces both the charge-transfer barrier at the electrode interface and the Li⁺ migration barrier within the SEI, ultimately enabling fast interfacial ion transport kinetics. Eventually, the electrolyte with this unique solvation structure (DMTMSA/FEC + LiTFSI/LiDFOB) exhibits high ionic conductivity (7.78 mS cm^-1) and rapid Li⁺ desolvation, enabling a LiNi_0.8Co_0.1Mn_0.1O₂ (Li||NCM811) to achieve an extended cycle life of 350 cycles at 1C with a capacity retention of 78.8%. Additionally, a 2 Ah Li||NCM811 pouch cell is successfully fabricated and demonstrates excellent cyclability exceeding 100 cycles. Therefore, this rational design concurrently achieves fast-charging capability and high stability in high-energy-density lithium metal batteries, paving a new avenue for electrolyte development.