Silicon carbon composite negative electrode material and preparation method thereof

A silicon-carbon composite and negative electrode material technology, applied in the direction of battery electrodes, rayon manufacturing, fiber chemical characteristics, etc., can solve the problems of limiting material cycle performance, reserving buffer space, etc., the process is simple and fast, and prevents electrical contact loss , Improve the effect of mechanical stability

Inactive Publication Date: 2019-05-03
HUNAN SHINZOOM TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The polyacrylonitrile (PAN) solution doped with Li and other nano-silicon particles is electrospun, and after oxidative carbonization, the nano-carbon fibers with silicon particles embedded in the carbon matrix are obtained, and this is used as the negative electrode material of the lithium-ion battery. The initial capacity It can reach 1000mAh / g, and after 50 cycles, the capacity decays to less than 700mAh / g, mainly because there is no buffer space reserved for the expansion of silicon in the carbon matrix, which limits the improvement of the cycle performance of the material; agglomeration, a large number of silicon particles are exposed on the surface of carbon nanofibers

Method used

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  • Silicon carbon composite negative electrode material and preparation method thereof
  • Silicon carbon composite negative electrode material and preparation method thereof
  • Silicon carbon composite negative electrode material and preparation method thereof

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Effect test

Embodiment 1

[0040] Use high-purity nitrogen to repeatedly purge the reaction furnace and vacuumize to ensure the safety of the system. Flow high-purity silane gas (99.99%) at a low flow rate of 2.0 L / min and keep it constant to heat the silane at 950°C. Decomposition, after 20 minutes using high-purity acetylene (C 2 h 2 ) gas into the same furnace, carbon coating was carried out at 950 °C at a flow rate of 2.0 L / min for 6 min, and finally the system was naturally cooled to room temperature under the protection of nitrogen, and the furnace powder S1 was collected.

[0041] Take S1 and add it to the DMF solution of polyacrylonitrile with a mass fraction of 3.40% (the mass ratio of S1 to the solution is 1:5), and use electrospinning technology (electrospinning is a polymer solution or a solution formed by the action of an electrostatic field) The process, when the electric field force of the charged polymer solution overcomes the surface tension, and when it is extruded from the spinneret,...

Embodiment 2

[0045] The reaction furnace was purged repeatedly with high-purity nitrogen and vacuumed to ensure the safety of the system. High-purity silane gas (99.99%) flowed at a low flow rate of 1.0 L / min and kept constant. Use silane to heat at 750°C. Decomposition, after 20 minutes using high-purity acetylene (C 2 h 2 ) gas in the same furnace at 750 °C for 10 min at a flow rate of 2.0 L· / min, and finally the system was naturally cooled to room temperature under the protection of nitrogen, and the furnace powder S1 was collected.

[0046] Take S1 and add it to 4.50% polyacrylonitrile DMF solution (the mass ratio of S1 to solution is 1:11), and electrospin the mixed solution in an electric field with an electric field strength of 75KV / m using electrospinning technology. The obtained polyacrylonitrile fiber membrane of silicon nanoparticles was dried under vacuum condition at 80° C. to remove the solvent. Then put it in a tube furnace for pre-oxidation (room temperature, 5°C / min, hea...

Embodiment 3

[0050] The experimental system was repeatedly purged and vacuumed with high-purity nitrogen to ensure the safety of the system. High-purity silane gas (99.99%) flowed at a low flow rate of 1.5 L / min and kept constant. Use silane to heat at 800 °C. Decomposition, after 20 minutes using high-purity acetylene (C 2 h 2 ) gas in the same furnace at 800 °C with a flow rate of 2.0 L / min for 7 min, and finally the system was naturally cooled to room temperature under the protection of nitrogen, and the furnace powder S1 was collected.

[0051] Take S1 and add it to a 3.40% polyacrylonitrile dimethylformamide (DMF) solution (the mass ratio of S1 to the solution is 1:9), and use electrospinning technology to mix the solution in an electric field with an electric field strength of 55KV / m Perform electrospinning. The obtained polyacrylonitrile fiber membrane of silicon nanoparticles was dried under vacuum condition at 60° C. to remove the solvent. Then put it in a tube furnace for pre-...

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Abstract

The invention provides a preparation method of a silicon carbon composite negative electrode material. Nano-silicon is prepared by employing a CVD method, then the nano-silicon is added to a DMF solution of polyacrylonitrile, electrostatic spinning is performed in an electric field, a silicon-carbon composite fiber is obtained, the silicon-carbon composite fiber, natural spherical graphite and asphalt are dissolved in a solvent for stirring and dispersing, then spray pyrolysis is carried out, and a high capacity silicon carbon composite material is obtained. The method is simple in equipment,is easy to operate and has good industrial application prospects. The silicon carbon composite negative electrode material prepared by the method has excellent electrochemical performance.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a silicon-carbon composite negative electrode material and a preparation method of a lithium-ion battery. Background technique [0002] Lithium-ion batteries have superior performance, wide range of uses, and broad prospects. Compared with traditional lead-acid batteries, nickel-cadmium batteries and nickel-hydrogen batteries and other secondary batteries, lithium-ion batteries have high energy density, high open circuit voltage, long cycle life, and self-discharge. It has obvious advantages such as low efficiency, no memory effect, green and pollution-free. With the continuous advancement of technology, lithium-ion batteries have been widely used in people's lives, such as portable electronic products, new energy vehicles and other fields. However, the mass specific capacity (Wh kg-1) and volume specific energy (Wh L-1) of lithium-ion batteries need to...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525D01F9/22D01F1/10
CPCY02E60/10
Inventor 李钰李能陈松彭杨城皮涛王志勇邵浩明余梦泽
Owner HUNAN SHINZOOM TECH
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