SURFACE PURIFICATION OF NATURAL GRAPHITE AND EFFECT OF IMPURITIES ON GRINDING AND PARTICLE SIZE DISTRIBUTION

摘要

The present invention relates to the specific physical or chemical purification of natural graphite ore. This purification is preferably applied to the surface of the natural graphite to allow the formation of a passivation film during the first discharge or the intercalation of lithium in the graphite when the latter is used in a lithium-ion battery. Grinding to a small size prior to purification allows optimization of the particle distribution, giving rise to a much more homogeneous electrode. This grinding is done in the presence of the natural impurities of graphite which play the role of micro-abrasive and gives a hardness to graphite which increases its mechanical properties.