LIB Anode, Graphite

Active Materials for Secondary Batteries are first mixed with binders and/or solutions and are then applied to the aluminum foil (cathode) or copper foil (anode) of the electrical current collector. After the drying process, the materials are processed to increase bulk density and finally become electrodes. In this passage, the production process of an anode active material (materials which takes in lithium ions during charging and releases electrons during electric discharge) specifically graphite materials will be introduced. Graphite Materials can be separated into two classifications, Natural Graphite, and artificially synthesized Artificial Graphite. Compared to artificial graphite, natural graphite is cheaper and has a higher graphitization degree. This allows natural graphite to store more lithium ions, becoming beneficial for increasing battery capacity. However, since most natural graphite has a flaky structure and low bulk density, the low electrode density characteristic makes it difficult to actually increase the battery capacity. Additionally, natural graphite has a tendency to become a planar structure on the electrical current collector, making it have low wettability characteristics. If these demerits of natural graphite can be solved, its merits of lower raw material cost compared to artificial graphite and possibility of increasing lithium ion battery capacities can be advantageous for the automobile industry. For solutions of these problems, spheroidizing the particles and surface treatment can enhance electron density as well as wettability respectively. On the other hand, the large production energy that is required for the manufacturing of artificial graphite makes the material very expensive. Also, the graphitization rate is lower compared to natural graphite. However, artificial graphite has the merit of being able to control composition (such as dispersing areas with different graphitization rates within the particle) and particle shape as well as inhibiting the decomposition of electrolytic solutions due to its low graphitization rate. From these features, the utilization of artificial graphite can increase the electron density, leading to large capacity batteries. In the artificial graphite process, a high-level of powder processing technology is needed in the processing stage before and after graphitization.In order to increase performance of active materials, the process for controlling the crystallization of the particle’s surface is essential. Since graphite has extremely bad wettability with water, organic solvents must be used to produce slurries for coating onto electric current collectors. While options of substituting the liquid with water-based solvents are possible, the mixing process is difficult. Therefore, processes to increase the water wettability of graphite particles are the norm.