UNIQUE EFFECT OF MECHANICAL MILLING ON THE LITHIUM INTERCALATION PROPERTIES OF DIFFERENT CARBONS

The effect of the carbon precursors morphology during a mechanical gri nding experiment on the physical/electrochemical properties of the res ulting ball-milled carbonaceous powders was studied. These properties strongly depend on the type of grinding mode used (shear or shock-type grinding); however, far each grinding mode, they were found to be tot ally independent of the nature of the precursor used (graphite, carbon , coke) and/or of its morphology (layers, microbeads and fibres). Eigh ty h of shock-grinding was found to produce carbonaceous milled powder s able to reversibly intercalate two lithiums per six carbons 'Li2C6' while still having an irreversible capacity of 0.8 Li. The,transparenc y of the precursor morphology and nature to mechanical grinding with c arbon materials is ascribed to the strong 2D character of the graphite structure. Finally, the observed large reversible capacity in our hyd rogen-free carbonaceous milled samples is explained on the basis of th e previously proposed 'house of cards' model.