Patent ID: 7993621

Claim:
A process for the preparation of natural graphite particles which are surfaced-purified and suitable for use an anode, said process comprising at least the following consecutive steps: a) a grinding of the natural graphite particles, carried out until said particles attain a size between 1 and 50 micrometers; and b) a purification of the graphite particles obtained in step a) performed by a chemical process according to one of the following steps: i one step purification in an aqueous acid medium containing at least one fluoridated derivative generating HF, in this case the concentration of fluoride derivative represents from 10 to 50% of the total weight of the acid medium; or ii one step purification using a fluoride compound generating HF and a non-fluoridated acid, the concentration of the fluoridated derivative generating HF ranging from 10 to 50% in weight and the acid concentration other than HF ranging from 10 to 30% in weight; or iii two-steps purification, using first a non-fluoridated acid then a derivative generating HF, the concentration in fluoridated derivative generating HF ranging from 10 to 50 weight % and the concentration in non-fluoridated acid ranging from 10 to 30% percent, wherein the step b) of purification being carried out for less than 16 hours and at a temperature lower than 250° C. and the resultant purified graphite particles are natural graphite particles which are surfaced-purified and suitable for use an anode.