A preparation method of silicon-carbon composite negative electrode material with high capacity

Abstract

The invention provides a preparation method of a high-capacity silicon-carbon composite negative electrode material. The method comprises three preparation steps of a composite material A, a composite material B and the silicon-carbon composite negative electrode material, wherein polystyrene, a carboxylated carbon nano tube and nanosized silica spheres are used in the preparation process of the composite material A; the composite material A and a sucrose solution are used in the preparation process of the composite material B; an argon furnace and argon are used in the preparation process of the silicon-carbon composite negative electrode material; and the prepared silicon-carbon composite negative electrode material is doped with small-particle size silica in a large-particle size polystyrene gap, so that the contact area and the compaction density of the silicon-carbon composite material can be improved and the internal resistance of the silicon-carbon composite material is reduced. The silica is expanded in the charge and discharge processes, but the spherical polystyrene can buffer expansion of the silica. Meanwhile, the polystyrene has a double-bond structure, so that the transmission rate of electrons can be improved and the rate capability of the silicon-carbon composite negative electrode material is improved.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion battery materials, in particular to a preparation method of a high-capacity silicon-carbon composite negative electrode material. Background technique [0002] Graphite anode material is the key material for lithium-ion batteries, and has become the first choice for lithium-ion battery anode materials due to its advantages of good cycle performance, strong stability, low price and high compatibility with electrolyte. [0003] In order to meet the market demand for high energy density of lithium-ion batteries, the current lithium-ion battery anode materials can no longer meet the market requirements in terms of gram capacity, rate performance and other parameters, so it is very urgent to develop high-capacity anode materials, and the current High-capacity anode materials mainly include silicon-carbon anodes, tin anodes, alloy anodes, etc., while the silicon-carbon anode material technology is r...

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Problems solved by technology

[0003] In order to meet the market demand for high energy density of lithium-ion batteries, the current lithium-ion battery anode materials can no longer meet the market requirements in terms of gram capacity, rate performance and other parameters, so it is very urgent to develop high-capacity anode materials, and the current High-capacity anode materials mainly include silicon-carbon anodes, tin anodes, alloy anodes, etc., while the silicon-carbon anode material technology is relatively mature, but the silicon-carbon anode has a large volume expansion during charging and discharging, making it difficult for industrial application

[0004] In view of the shortcomings of silicon-carbon anodes, domestic researchers mainly reduce the expansion of silicon materials through measures such as surface coating of silicon materials. For example, Chinese patent CN105118974 A discloses a silicon-based anode material and its preparation method, which introduces carbon nanofibers to reduce the expansion of silicon materials. The volume expansion of silicon nanoparticles avoids the breakage of silicon particles and the repeated generation of SEI film, and improves the mechanical strength of negative electrode materials, but the preparation process is complicated, the stability is poor, the process is complicated, and it is difficult to industrialize production

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