Silicon anode material with spherical thorn-shaped structure and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion battery electrode materials and preparation thereof and discloses a silicon anode material with a spherical thorn-shaped structure and a preparation method thereof, and belongs to the technical field of lithium ion battery electrode materials and preparation thereof. A silicon source compound, a hydrolyzing agent, a reducing agent and a surfactant are added into an inert solvent, the suspension liquid is transferred to a closed reaction kettle, and a silicon-oxygen material precursor is prepared through a hydrothermal method; then conductive carbon coating is conducted on a silicon oxide compound by adopting a vapor deposition method under the protection of nitrogen, and finally cooling is executed to obtain the silicon anode material with the spherical thorn-shaped structure, wherein the chemical formula of the siliconanode material is SiOx/C, and x is greater than 0 but is smaller than 1. The gram capacity of the first reversible discharge of the silicon anode material prepared by the preparation method is 2101 mAh/g and the first efficiency is 86% under the current of 0.1C, the capacity retention rate is 100% after 100charge-discharge cycles under the current of 0.5C, and the silicon anode material has excellent electrochemical performance.

Description

technical field [0001] The invention belongs to the technical field of lithium ion battery electrode materials and preparation thereof, and in particular provides a silicon negative electrode material and a preparation method thereof. Background technique [0002] With the continuous improvement of the endurance requirements of new energy vehicles, the energy density requirements of lithium-ion batteries as a power source are also rising. At present, increasing the energy density of lithium-ion batteries in the industry mainly focuses on the development of high-nickel ternary cathode materials and high-capacity silicon anode materials. The theoretical gram capacity of silicon material can reach 4200mAh / g. Compared with the traditional graphite anode material (372mAh / g), it has obvious advantages in gram capacity, and the earth reserves of silicon element are high. It has become a hot spot in the development of anode materials in the industry. [0003] However, during the ch...

AI Technical Summary

Problems solved by technology

The continuous expansion and contraction of silicon negative electrode materials will bring a series of problems: 1. The cracking of silicon particles will cause the material to pulverize and the pole piece will fall off; 2. The surface of the cracked silicon particles will form a new SEI film with the electrolyte, which will consume limited lithium. 3. The continuously generated SEI film will increase the internal resistance of the battery

Although the invention prepares a hollow carbon-coated silicon negative electrode material by copper oxide template method and organic carbon source pyrolysis method, which can improve the cycle performance of silicon materials to a certain extent, but the method of the invention is complex and does not have industrial production feasibility

Moreover, in the cold pressing process of the battery manufacturing process, the silicon negative electrode material of the invention will have a hollow structure crushed and crushed, and lose the buffer space that can accommodate the volume expansion of silicon, resulting in a sharp deterioration in the electrical properties of the silicon negative electrode material.

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