TEM characterization of the passivating layer formed during the reduction of graphite electrodes in selected electrolytes

The electrochemical intercalation of lithium ions into graphite was studied in various electrolytes. The first cycle is accompanied by the irreversible process attributed to the formation of a passivating layer. The reduction of Cl–EC and EC begins at potentials equal to 1.7 and 0.9 V vs. Li+/Li, respectively. The electrochemical behaviour is considerably affected by the nature of the salt. Contrary to LiBF4, a good cycleability is obtained with LiClO4 and LiAsF6.