The Effect of Pre-Analysis Washing on the Surface Film of Graphite Electrodes

Electrodes are routinely washed to remove electrolyte deposits, salt, and high boiling point solvents prior to analysis with surface-sensitive techniques. The effect of washing on the surface films of graphite electrodes from LiCoO2/graphite cells, which contained varying amounts of vinylene carbonate (VC), was investigated by comparing the microstructure and chemical composition. We confirmed that there are two different kinds of films on the surface of the electrodes: one at low and one at high VC content concentration. Far from being limited to remove extraneous salt deposits from the surface of the sample, DMC washing was found to completely remove one and to affect the composition of deeper strata in the other.