Surface analysis of solid electrolyte interphase on binder-free graphite electrodes in advanced electrolytes

The solid electrode interphase (SEI) on graphite electrodes is important to the performance, calendar life, and safety characteristics of lithium-ion cells. This transaction examines the SEI formed on binder-free (BF) graphite electrodes prepared by electrophoretic deposition. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) data were obtained on electrodes cycled in cells containing four electrolytes comprising ethylene carbonate (EC): ethylmethyl carbonate (EMC) (3:7 by wt.) solvent and 1.2M LiPF6, IM LiF2BC2O4, IM LiBF4, or 0.7M LiB(C2O4)2 salt. Our observations suggest that, in addition to solvent reduction, the reduction of electrolyte salts play an important role in SEI formation. ©The Electrochemical Society