Constructing a Highly Robust Interface Film for Enhancing Rate Performance of Graphite Anode via a Novel Electrolyte Additive.

Abstract

Solid electrolyte interphase (SEI) is regarded as a key factor to enable high power outputs of Lithium-ion batteries (LIBs). Herein, we demonstrate a modified electrolyte consisting of a novel electrolyte additive, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (FTMS) to construct a highly robust and stable SEI on a graphite anode for LIBs to enhance its rate performance. With 2% FTMS, the anode presents an improved capacity retention from 77.6 to 91.2% at 0.5 C after 100 cycles and an improved capacity from 86 to 229 mAh g-1 at 2 C. Experimental characterizations and theoretical calculations reveal that FTMS is preferentially absorbed and reduced on graphite to construct an interface chemistry with uniform fluoride-containing organic lithium salt and silicon-containing polymer, which exhibits high flexibility and conductivity and endows the SEI with high robustness and stability. This work provides an effective way to address the issue of slow lithium insertion/desertion kinetics of graphite anodes.