A kind of preparation method of silicon graphite anode material
Lithium-ion batteries have many advantages such as high voltage, high energy, long cycle life, and no memory effect, and have been widely used in consumer electronics, power tools, medical electronics, energy storage and other fields. In the structure of the battery, the anode material is one of the key factors affecting its performance. At present, the commonly used anode materials mainly include graphite, carbon, and lithium titanate. The specific capacity of graphite and carbon anode materials is generally in the range of 300~400mAh/g, and the specific capacity of lithium titanate is only 170mAh/g and the voltage platform is too high (1.5V vs Li+/Li). This greatly affects the energy density of the battery, thereby affecting the miniaturization of the battery and its application in fields such as electric vehicles.
As a negative electrode material, silicon has the characteristics of high specific capacity (4200mAh/g), environmental friendliness, and abundant reserves. Because of its wide attention, it is considered as the negative electrode material for next-generation high-energy-density lithium-ion batteries. But silicon still has some problems that affect its application. One is that the reversible capacity of silicon is proportional to the volume expansion during the lithium storage process. For example, when the capacity reaches 3590mAh/g, the corresponding volume expansion can reach 320%, thus affecting the processing and design of the battery. At the same time, the volume change will lead to the granulation of silicon, and the active material will fall off from the current collector, thus seriously affecting the cycle performance of the battery.
The particleization of silicon during cycling also causes the fresh silicon surface to be exposed to the electrolyte to continuously generate a solid electrolyte interface (SEI), which continuously consumes the lithium source and electrolyte inside the battery, resulting in continuous battery capacity decay and internal resistance. Increase. Therefore, it is necessary to develop new materials and technologies to reduce or avoid the volume expansion problem of silicon materials and to avoid the problem of continuous SEI. At present, in response to this problem, it is one of the more effective methods to use carbon materials to prepare composite materials. The silicon material is coated with carbon, so as to avoid the contact between silicon and the electrolyte, and at the same time, the coating can be fixed on the carbon material. inside to prevent it from falling off. However, the preparation method suitable for production still needs to be studied and explored.
The technology provides a preparation method of silicon graphite anode material. The expanded graphite is used as a raw material, an organic dispersion of nano-silicon is adsorbed, and then heat-treated to obtain an expanded graphite-silicon composite material, and the silicon graphite anodematerial is obtained by flattening a pair of rollers. . The silicon graphite anode material has the characteristics of high initial efficiency, high cycle life and high capacity, and the method is simple in process, easy to obtain raw materials, and the organic dispersion used can be recycled, which is green and environmentally friendly, and is easy to industrialize production.
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Luoyang Moon & Star New Energy Technology Co., LTD, founded on October 17, 2008, is a high-tech enterprise committed to the research and development, production, processing, sales and technical services of graphite anode materials, we are high quality graphite anode supplier. Our Company has a diversified product structure with natural graphite, artificial graphite, composite graphite, intermediate phase and other negative materials (silicon carbon materials, etc.). The products are widely used in high-end lithium ion digital, power and energy storage batteries.
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