Different types of graphite materials, i.e. synthetic graphite flakes and natural graphite flakes which are used as anode materials in Li-ion batteries were studied. Differences in the electrochemical behavior of electrodes comprised of these materials, mainly in their irreversible capacity, could be correlated to the differences in the particle morphologies and their crystal structure. We propose that graphite particles with a large amount of crevices in their edge planes can crack, due to a build-up of internal pressure as a result of reduction of solution species on the carbon surfaces during the first cathodic polarization on the electrodes. Another important factor determining the electrodes’ stability is the existence of some disorder in the particles’ structure.