High-capacity carbon-silicon negative electrode active material and preparation and application methods thereof

Abstract

The invention discloses a high-capacity carbon-silicon negative electrode active material and preparation and application methods thereof. The high-capacity carbon-silicon negative electrode active material achieves a specific capacity of 800-1500 mAh/g and is formed by mixing carbon-silicon materials and graphite materials, wherein the carbon-silicon materials are microspherical particles prepared by performing ball milling spray-drying and thermal treatment processes on nanosilicon, crystalline flake graphite, carbon nanotubes and a carbon source, the nanosilicon is dispersed on the surfaceof the crystalline flake graphite, the carbon nanotubes are inserted into pores formed between the carbon nanotubes and the crystalline flake graphite, pyrolytic carbon of the carbon source is coatedon the surface of the nanosilicon and the surface and pores of the spherical particles formed by the nanosilicon, the crystalline flake graphite and the carbon nanotubes; the weight of silicon-carbonmaterials is 25%-80% of the total weight of the high-capacity carbon-silicon negative electrode active material. When uniformly mixed with conducting agent and bonding agent, the high-capacity carbon-silicon negative electrode active material can be coated or deposited onto copper foils, foamed nickel, foamed copper or carbon fiber paper as the negative electrode of a lithium ion battery. The preparation method of the high-capacity carbon-silicon negative electrode active material is simple in process, low in cost, applicable to amplified preparation of long-circulation carbon-silicon materials.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a high-capacity silicon-carbon negative electrode active material (800-1800mAh / g) and a preparation method and application thereof. Background technique [0002] In recent years, with the aggravation of environmental pollution and energy shortages, emerging industries represented by new energy vehicles have developed rapidly. As a power battery with long cycle life, high power density, low self-discharge rate and green environmental protection, lithium-ion battery has ushered in new opportunities, but also faces great challenges. At present, the energy density and cruising range of power lithium-ion batteries are difficult to meet the needs of electric vehicles. [0003] Graphitized carbon material is the most commonly used negative electrode material for commercial lithium-ion batteries. It has good conductivity and stable cycle, but its theoretical sp...

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Problems solved by technology

[0006] In order to solve the problems of poor cycle performance, complex preparation process, low output and high cost of high-capacity silicon-carbon negative electrode active materials, the present invention provides nano-silicon, micron flake graphite, carbon nanotubes and pyrolytic carbon as raw materials, and utilizes ball milling Simple and easy-to-scale technologies such as spray drying and spray drying are used to construct silicon-carbon materials with good pore structure and conductive network; and a process method for preparing high-capacity, long-cycle silicon-carbon negative electrode active materials (800-1800mAh / g) with graphite materials

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