Comparisons between A.C impedance behaviour of graphite hydrogenosulfate and p-doped (CH)x

An electrocapillarity approach has been proposed in previous papers for electrochemical intercalation of H 2 SO 4 into graphite, which explains the high capacitive values (170 F/g) deduced from equilibrium potential charge curves or from low frequency a.c. impedance measurements (extending the double layer capacitance to the intercalated electrolyte — graphite interface). We propose here a similar view for GaCl 4 − intercalated (CH) x ; “switching” between doped and undoped (CH) x may correspond to the faradic like stage transformation of Graphite Intercalation Compounds (GIC), while a charging process of (CH) x chains with counter-ions recalls the capacitive “overcharging” of pure-stage GIC.