Screening of F-containing electrolyte additives and clarifying their decomposition routes for stable Li metal anodes

Constructing a LiF-rich solid electrolyte interphase (SEI) is a feasible strategy for inhibiting lithium (Li) dendrites of Li metal anodes (LMAs). However, selecting appropriate F-containing additives with efficient LiF contribution is still under active research. Herein, a series of fluorinated additives with diverse F/C molar ratios are investigated, and we demonstrate that the hexafluoroglutaric anhydride (F6−0) holds the best capability to derive the LiF-rich SEI in regular carbonate electrolytes (RCEs). To ameliorate the decomposition kinetics of the F6−0, LiNO3 (LNO) as an adjuvant is further introduced in the system. As a result, the reduction efficiency of F6−0 is increased to 91% under the F6−0/LNO synergistic effect, enabling the LMA with a uniform LiF-rich SEI in the RCE with merely 4 vol. % F6−0/LNO (F6L) addition. The LiNi0.8Co0.1Mn0.1O2||Li-20μm full-cell with the F6L also showcases better cycling and rate performances than the cases with other F-containing additives. A F-containing additive with efficient LiF contribution is urgent for Li metal batteries. The authors report a hexafluoroglutaric anhydride additive with a 91% conversion, enabling the Li metal anode with a LiF-rich interphase in regular electrolyte.