Electrochemical lithiation and compatibility of graphite anode using glutaronitrile/dimethyl carbonate mixtures containing LiTFSI as electrolyte

摘要

The compatibility of glutaronitrile (GLN) and its mixtures with dimethyl carbonate (DMC) containing lithium bis-(trifluoromethane sulfonyl) imide (LiTFSI) with graphite negative electrode was investigated. GLN/DMC/LiTFSI electrolytes’ mixtures were characterized in terms of their ionic conductivities and viscosities. Cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy were performed in order to study the performances of the graphite anode in the GLN-based electrolytes. Results clearly indicate that no significant Li intercalation occurs in graphite in pure GLN, but when GLN/DMC (1:1 and 1:3 w/w) mixtures were used, the cycling ability of the electrode was improved as the coulombic efficiency reaches 98 and 99%, respectively. Moreover, SEM images of the graphite anode indicate that after being cycled in GLN-based electrolytes, the electrode surface was homogenously covered by a Solid Layer Interface which insures a reversible lithiation of graphite anode.