Synergic Regulation of Li ⁺ Desolvation Kinetic and Li Metal Interfacial Chemistry toward Fast-Charging Li Metal Batteries

Batteries with Li metal anodes are promising to achieve ultrahigh energy densities over 500 Wh kg–1. However, Li dendrite growth and related issues hinder their practical application. Although strategies like “salt-in-solvent” and “weakly solvating” approaches have been successfully demonstrated to suppress the dendrite growth and achieve high energy densities by enhancing the oxidative tolerance of ethereal electrolytes, they often compromise Li+ dissociation, thus undermining their fast-charging performance. Herein, we propose a synergic regulation strategy of Li+ desolvation kinetic and Li metal interfacial chemistry via the addition of hexafluorobenzene (HFB) and ionic liquid (N-propyl-N-methylpyrrolidinium nitrate (Py13NO3)). In this electrolyte, NO3– and FSI– anions penetrates into the inner solvation shell of Li+, weakening the solvation strength of 1,2-Dimethoxyethane (DME), meanwhile, the Py13+ drags the FSI–, NO3– anions and the DME, thus prompting the desolvation process of Li+. Meanwhile, the interfacial adsorption of HFB facilitates the formation of a LiF-rich interphase with improved ionic conductivity. Consequently, the electrolyte containing 2 M LiFSI 0.3 M Py13NO3 in DME/HFB (9/1, v/v) demonstrates excellent cycling stability in high-voltage Li || NCM811 cells, maintaining 83.8% capacity retention over 800 cycles at a high rate of 5 C. Notably, even under a stringent negative/positive capacity (N/P) ratio of 1, the capacity retention of 82.1% is still retained after 100 cycles.