Fluorinated Solid Electrolyte Interphase Derived From Fluorinated Polymer Electrolyte To Stabilize Li Metal

Abstract

Unstable interface between highly reductive Li metal and a conventional liquid electrolyte leads to uncontrollable Li dendrites and Li pulverization, thus limiting the practical applications of Li metal batteries with high energy density. Herein, a fluorinated quasi-solid polymer electrolyte is synthesized to stabilize Li metal via the C-F/LiF enriched solid electrolyte interphase (SEI) derived from the fluorinated polymer skeleton. Benefiting from the homogenized ion plating/stripping process guided by lithophilic C-F and rapid Li⁺ transportation assisted by LiF, Li dendrites and Li pulverization are suppressed. As a result, the Li||Li symmetrical cell with the fluorinated quasi-solid polymer electrolyte remains stable over 1400 h at a current density of 0.3 mA cm^-2 . LiNi_0.8 Co_0.1 Mn_0.1 O₂ ||Li battery delivers a long-term cycling performance, where the capacity retains 87.77 % of its initial state after 300 cycles at 0.5 C in the voltage range from 2.8 to 4.4 V.

Keywords: Dendrites; Energy storage; Lithium metal battery; Quasi-solid polymer electrolyte; Solid electrolyte interphase.