Fig.1

(a) schematic diagram of surface pretreatment of Li plates;(b),(c),(d)SEM images of Li plates after processing:(b) cross-section, (c) top view, (d) top view at high magnification; and the inset in (c) is the top view of Li plates before processing"

Fig.2

(a～c) the Li 1s、C 1s、F 1s spectra of Li after processing; (d) XPS of the protection film "

Fig.3

(a) cycling performance of Li|Li symmetric cells under Ar atmosphere, with untreated Li (black line) and pretreated Li (red line); EIS of (b) the comparision group and (c) the experiment group"

Fig.4

(a),(b) SEM images of the untreated-Li plates after 120 h cycling with top view (a) and cross-section (b);(c),(d) SEM images of the pretreated-Li plates after 120 h cycling with top view (c) and cross-section (d)"

Fig.5

(a) Full discharge and charge curves of Li-O2 batteries based on untreated Li (black line) and pretreated Li (red line); (b) XRD spectra of the cathodes after charging (black line) and discharging (red line); SEM images of the cathodes after discharging (c) and charging (d)"

Fig.6

The charge-discharge curves of the Li-O2 batteries based on untreated Li (a) and pretreated Li (b); (c) the cycling performance of the Li-O2 batteries based on untreated Li (green line) and pretreated Li (orange line)"

Fig.7

SEM images of the untreated Li plates(a) and pretreated Li plates(b) in Li-O2 batteries after 10th cycling with top view"