INVESTIGATION OF THE EFFECT OF MECHANOCHEMICAL ACTIVATION IN A SHOCK-REFLECTIVE MILL ON THE CRYSTAL STRUCTURE OF NATURAL GRAPHITE

Abstract

In this work, studies the changes in the crystal structure of the natural graphite of the Taiga deposit were carried out in the process of spheroidization. The spheroidization process consisted in giving the flat graphite particles of a quasi-spherical shape due to mechanochemical activation in a centrifugal mill of the shock-reflective principle of action. Spherical graphite obtained by mechanochemical spheroidization is currently the dominant anode material of lithium-ion batteries on the market. Currently, the problem of obtaining electrode materials based on domestic raw materials and using domestic processing technologies is becoming urgent. In the course of the work, it was found that the graphite under study consists of two graphite substructures with a greater and lesser degree of graphitation. During mechanochemical activation of graphite in a centrifugal mill of the shock-reflective principle, a significant change in the crystal structure of both substructures occurs, consisting in a decrease in the size of the crystallites, a decrease in the degree of graphitation and the formation of a rhombohedral phase. It is also noted that the changes in the structure are wave-like, and the less graphitized substructure is subject to stronger fluctuations. In the process of spheroidization, a decrease in the proportion of a more graphitized substructure and its transition to a less graphitized one was noted. In addition, it was found that the spheroidization process is accompanied by a decrease in the degree of texture of the crystal structure, expressed by a decrease in the ratio of the integral intensities of reflexes (002) and (110) corresponding to the crystallographic planes "c" and "a", respectively. An increase in the intensity of the impact from 55 m/s to 85 m/s makes it possible to intensify the ongoing processes, while no significant deterioration in the degree of graphitation was noted.