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

Abstract

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 (F_6-0) holds the best capability to derive the LiF-rich SEI in regular carbonate electrolytes (RCEs). To ameliorate the decomposition kinetics of the F_6-0, LiNO₃ (LNO) as an adjuvant is further introduced in the system. As a result, the reduction efficiency of F_6-0 is increased to 91% under the F_6-0/LNO synergistic effect, enabling the LMA with a uniform LiF-rich SEI in the RCE with merely 4 vol. % F_6-0/LNO (F6L) addition. The LiNi_0.8Co_0.1Mn_0.1O₂||Li-20μm full-cell with the F6L also showcases better cycling and rate performances than the cases with other F-containing additives.