The behaviour of petroleum coke (CONOCO) was examinated in a PC/EC/DMC (1/1/3 volume) mixture with LiCF3SO3 as the lithium salt. The influence of the lithium content on the diffusion coefficient of lithium ions has been explored and the reactivity of the intercalated lithium in petroleum coke with small volumes of electrolyte at 45 degrees C has been investigated. This reactivity was found to be greater with a V2O5 cathode and a mechanism is proposed to explain this tendency,