Analysis on the application of silicon materials in lithium batteries

Analysis: What are the advantages of silicon negative film in the application of silicon in lithium batteries. The theoretical energy density of graphite is 372mAh/g, and the negative energy density of silicon is 10 times 4200mAh/g. It is environmentally friendly and has abundant reserves. The participation of materials in promoting the energy density of silicon batteries is recognized as one of the directions of the industry.Japan and South Korea are large battery manufacturers, such as the commercialization of silicon carbon anode batteries, such as BYD, Lishen, BAK, GM and other domestic battery manufacturers. They are all following up, but so far we have not seen any products that have stopped processing. The Panasonic 18650 battery selected by Tesla contains 10% silicon in the traditional graphite anode material, and the energy density is at least 550mAh/g. The use of silicon in lithium batteries The application of silicon materials in lithium batteries involves two important aspects: one is to participate in the formation of silicon-carbon cathode in the cathode material of nano-silicon; the other is to participate in the synthesis of organic silicon compounds in the electrolyte to improve the performance of the electrolyte. Nano silicon: an important part of lithium anode materials. Nano silicate refers to crystalline silicon particles with a diameter of less than 5 nanometers. It is an important non-metal amorphous material and is commonly prepared by the sol-gel method. Nano silicon powder has the characteristics of high purity, small particle size, uniform distribution, large specific surface area, high surface activity, low bulk density, non-toxic and odorless. Nano-silicon is widely used in the following fields: silicon-carbon composite materials composed of graphite materials, as the negative electrode material of lithium batteries, greatly increase the capacity of lithium batteries, which is the focus of our attention; used to process high-temperature coatings and refractory materials; (3) It is mixed with high-pressure diamond to form a silicon carbide-diamond composite material, which is used as a tool; it can react with organic matter and is an organic silicon polymer material; (5) Polysilicon is made of purified metal silicon; semiconductor microelectronic packaging material; Metal finish. Organosilicon: Functional additive for lithium electrolyte. Organosilicon is an important synthetic polymer material composed of silicon and oxygen atoms. Because the silicon-oxygen structure of the main chain has a strong chemical bond, the molecules of organosilicon polymers are more stable than those of ordinary organic polymers. The organic silicon structure makes it have the functions of both inorganic and organic materials, low surface tension, temperature coefficient of viscosity, high compressibility and high-grade basic properties of air permeability, high temperature and low temperature resistance, electrical insulation, oxidation stability, Weather resistance, flame retardant, moisture resistance, corrosion resistance, non-toxic, odorless, and physiological inertness and other excellent characteristics, widely used in aerospace, electrical appliances, electronics, construction, transportation, chemicals, textiles, food, light industry, medical And other industries, including silicones are first used for sealing, bonding, lubrication, coatings, surface activity, mold release, defoaming, inhibition, waterproofing, moisture-proof, inert fillers, etc. Although the function of mechanical silicone is not much different from other materials at room temperature, its physical and mechanical functions at high and low temperatures are prominently altered at 60+250°C and its function is not affected. Therefore, silicone polymers can be used for In this temperature region for a long time, and some silicone polymers can be used normally at temperatures as low as -100°C. Defects of silicon anode material The defects of silicon anode material are suitable. There are two important defects: 1) Silicon is embedded in the lithium ion intercalation process, which will cause the volume of silicon to expand by 100% to 300%, and greater internal stress is inside the material. Damage to the material structure, the electrode material on the copper foil, and the silicon on the surface of the SEI film-break to form a repeated form, reduce the conductivity of the electrode and cycle safe sexual behavior; silicon is a semiconductor, and its conductivity is much worse than that of graphite. This leads to a large degree of irreversibility in the process of lithium ion de-embedding, which further reduces the Coulomb power of its roughness. Therefore, it is necessary to solve the problems of silicon volume expansion and low initial charge and discharge power. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: Why are most of the lithium batteries small?