Fig. 6: Characterization of negative electrode morphology and the corresponding composition of Li||NCM811 cell after 50 cycles (1 C rate) at 60 °C (3.0–4.3 V).

SEM images of Li metal negative electrode surface after cycling. a E-LiFAS and b E-base, scale bar is 10 μm; c E-LiFAS and d E-base, scale bar is 1 μm. e, f XPS analysis of the cycled Li metal negative electrode in different electrolytes. TOF-SIMS 3D reconstruction maps of AlF4- and LiF2- in the different electrolytes: E-LiFAS (g) and E-base (h). Schematic diagram of Al corrosion mechanism of LiTFSI (i) and Al protection mechanism of LiFAS (j).