Effect of atmosphere on the mechanical milling of natural graphite

Natural graphite was ball milled in a vibratory and a planetary mill under different atmospheres. Its microstructure was found to evolve very differently when milled in oxygen and in an inert atmosphere. This phenomenon is most pronounced when it was milled in a planetary mill where the deformation forces are mainly shear in nature. Mechanically induced oxidation on the surface, probably along the edges of the graphene planes, is responsible for suppressing the fracture rate and preserving the crystallinity of natural graphite milled in oxygen. Understanding this mechanochemical process may open up a new route for the synthesis of carbonaceous materials suitable for lithium ion battery applications. (C) 2000 Elsevier Science Ltd. All rights reserved.