Fluorine-containing silicon monoxide negative electrode material and preparation method and application thereof

Abstract

The invention discloses a fluorine-containing silicon monoxide negative electrode material and a preparation method and application thereof. The mass content of fluorine in the fluorine-containing silicon monoxide material is 1-20%, and the fluorine elements are uniformly distributed on the surface of silicon monoxide; the average particle size of the fluorine-containing silicon monoxide materialis 10-70 [mu] m. The preparation method comprises the following steps: mixing and grinding silicon monoxide powder and ammonium fluoride powder to obtain silicon monoxide-ammonium fluoride composite powder; and sintering the silicon monoxide-ammonium fluoride composite powder under the protection of inert gas to obtain the fluorine-containing silicon monoxide negative electrode material. The negative electrode material obtained by the method can form a LiF fast ion conductor layer to coat the surfaces of silicon monoxide particles in the charging and discharging process, formation of a more stable SEI film is promoted, and the electrochemical performance of a battery is improved. The raw materials adopted by the invention are low in cost, the preparation process is simple, a toxic fluorine-containing additive or a fluorine-containing additive with harsh use condition requirements is not adopted, the safety is high, and the method is suitable for large-scale production.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery negative electrode materials, and in particular relates to a fluorine-containing silicon monoxide negative electrode material and a preparation method and application thereof. Background technique [0002] In recent years, with the rapid development of the new energy industry, lithium-ion batteries have been widely used in the fields of electronic products, power batteries and energy storage due to their advantages such as high energy density and long cycle life. However, with the continuous improvement of battery performance requirements for electric vehicles and hybrid vehicles, the development of high-power and high-energy-density lithium-ion batteries has become an urgent problem to be solved. The positive and negative electrode materials of lithium-ion batteries are closely related to the performance of the battery. At present, the energy density of commercial graphite anode materials has ...

AI Technical Summary

Problems solved by technology

At present, the energy density of commercial graphite anode materials has reached the bottleneck, and it is difficult to have room for improvement, while silicon-based anode materials have a high theoretical specific capacity (Si: 4200mAh g -1 , SiO: 2500mAh·g -1 ), low lithium-deintercalation potential, and abundant reserves are considered to be the most promising next-generation lithium-ion battery anode materials that can replace graphite anodes.

[0003] The silicon-based negative electrode provides capacity through the process of alloying and dealloying with lithium ions during charge and discharge, and this process will produce a huge volume expansion (about 300%), which will lead to many problems, such as: 1. Huge volume expansion will lead to crushing and powdering of silicon-based material particles; 2. A large amount of pulverized material will peel off from the current collector, resulting in capacity attenuation and poor cycle performance; 3. Repeated volume changes during charge and discharge will make the material The SEI film (solid electrolyte interfacial film) on the particle surface is constantly broken and reconstructed, which will consume a large amount of active lithium, which will reduce the capacity retention and coulombic efficiency

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