A morphological study of SEI film on graphite electrodes

Morphological features of the protective layer on the graphitic electrodes, formed by reduction of electrolytic solution components during the first cycle, are investigated by SEM and common electrochemical techniques. As expected, the interaction between electrode and solution is very important, leading to quite different results for different solutions. Here, results for solution of various solvents ratio are reported. It appears that the performances of the electrodes are strongly dependent on their surface chemistry in solutions. We can conclude that the nature of the surface film plays a key role for the electrode stability or to capacity decrease always related to an increase of the electrode itself impedance.