Fig. 4: Performance characterizations of metallic Li at different temperatures.

a–c Li deposition profiles in liquid electrolyte, non-fluorinated quasi-solid polymer electrolyte, and fluorinated quasi-solid polymer electrolyte at 0.5 mA cm⁻² with a cutoff capacity of 5 mAh cm⁻². Optical photographs and SEM images of Cu current collectors after the corresponding deposition experiments in liquid electrolyte (d), non-fluorinated quasi-solid polymer electrolyte (e), and fluorinated quasi-solid polymer electrolyte (f). g Atomic ratios of F and O in the SEI formed in different electrolytes at different sputtering time periods. The characterized Li metal negative electrodes were collected from Li | |Li symmetric cells after 10 times Li plating/stripping at 30 °C and 0.3 mA cm⁻² with a cut-off capacity of 0.6 mAh cm⁻². hThe activation energy of Li⁺ desolvation process derived from Nyquist plots of cycled Li | |Li symmetric cells with different electrolytes after 20 times Li plating/stripping at 0.3 mA cm⁻² with a cutoff capacity of 0.6 mAh cm⁻². i Li⁺ desolvation activation energy obtained from quantum chemistry simulations of different electrolytes.