Modification of Graphite Anode Materials for Lithium-Ion Batteries

Graphite is currently the most widely used anode material for lithium-ion batteries, and the growing market demand has put forward higher requirements for the lithium storage performance of graphite anode materials. In this paper, the working principle of lithium-ion batteries and the mechanism of graphite lithium intercalation are summarized. In view of the problems of low theoretical specific capacity (372 mA·h/g) and poor electrolyte compatibility of graphite anode materials, the modification methods of graphite anode materials in recent years are summarized. It is mainly divided into two categories: surface modification and structure regulation, in which the surface modification technology includes oxidation and halogenation treatment, featuring on adjusting the chemical properties of the interface, so that the modified graphite anode material takes into account the advantages of the internal graphite itself and good electrolyte compatibility on the surface, which can effectively inhibit the occurrence of undesirable results such as graphite volume expansion, exfoliation and pulverization, and improve the first cycle coulomb efficiency and working stability of graphite anode materials. However, surface coating can only reduce the irreversible capacity loss, and cannot effectively enhance the lithium storage capacity of anode materials. The structure regulation includes exfoliation method and defect construction, which is characterized by expanding the graphite layer spacing, reducing the graphite dimension and constructing defects on the graphite structure, increasing the active sites of lithium ions, providing more lithium ion diffusion channels, alleviating the cycle process, and significantly improving the lithium storage performance of graphite. Furthremore, the future development trend of graphite anode materials is promising. For example, optimize and explore the preparation process of 3D graphene and graphite composite, and master the influence rules and mechanisms of 3D graphene morphology and size on the electrochemical performance of anode materials. In addition, although element doping can significantly improve the energy density of anode materials, there is currently a lack of uniform, stable and efficient doping processes and methods. In comparison, it is feasible to build up intrinsic defects to improve energy density. Moreover, the research on making defects by high-energy beams, like electron beam irradiation should be increased. Due to its unique energy characteristics, accurate, efficient, multi-scale and multi-directional defect construction can be carried out on graphite. Combining with theory and practice, this paper selectively carries out research on new graphitized carbon composite materials, such as the production technology of highly stable graphitized carbon/Si, graphitized carbon/Sn and other composite materials. © 2022, Chongqing Wujiu Periodicals Press. All rights reserved.