fig2

Figure 2. (A) Voltage profiles of Li/Li symmetrical cells using either 1 M LiTFSI in PC (+ Whatman GF/D as separator) or PTFSI-5/10-70 as an electrolyte at 20 °C. Current density: 2 mA cm^-2 reversed every 30 min (i.e., 1 mAh cm^-2 cycled at 2C). (B) Impedance spectra acquired every five cycles for a 1M LiTFSI, PC Li/Li cell cycled at 2 mA cm^-2. (C) Impedance spectra acquired every five cycles for a PTFSI-5/10-70 Li/Li cell' cycled at 2 mA cm^-2. (D) SEM image of a lithium electrode after plating 10 mAh cm^-2 at 1 mA cm^-2 at 20 °C in 1M LiTFSI, PC (+ Whatman GF/D separator). (E) SEM images of a lithium electrode covered by PTFSI-4/10-70 after plating 10 mAh cm^-2 at 1 mA cm^-2 at 20 °C using PTFSI-5/10-70 as the electrolyte.