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High-compaction-density lithium ion battery silicon-carbon negative electrode material and preparation method thereof

A lithium-ion battery and negative electrode material technology, applied in battery electrodes, secondary batteries, circuits, etc., can solve the problems of unsatisfactory conductivity of silicon-carbon composite materials, unfavorable pole piece coating process, low compaction density, etc., to achieve Ensure structural integrity and stability, improve electrochemical stability, and enhance the effect of electron transport capabilities

Inactive Publication Date: 2019-04-05
湖南宸宇富基新能源科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this structure, because there is a reserved space between silicon and carbon, the stress damage caused by the volume expansion of silicon to the carbon shell can be relieved, but this material has a low compaction density and a high specific surface area, which is not conducive to obtaining The battery pole piece with high surface loading is also not conducive to the later pole piece coating process
Even if the rolling treatment is carried out in the post-electrode optimization, it is very easy to cause structural damage to the shell-core structure.
In addition, the carbon used is mostly amorphous carbon, and the conductivity of the obtained silicon-carbon composite material is not ideal.

Method used

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  • High-compaction-density lithium ion battery silicon-carbon negative electrode material and preparation method thereof
  • High-compaction-density lithium ion battery silicon-carbon negative electrode material and preparation method thereof
  • High-compaction-density lithium ion battery silicon-carbon negative electrode material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0055] (1) Take 1 g of silicon particles with an average particle size of 50 nm, add 20 g of agate into an agate mortar and perform ball milling at a speed of 200 r / min for 8 hours.

[0056] (2) Place the ball-milled silicon particles, mesocarbon microspheres (1g), and polyvinylidene fluoride (0.2g) in a mixer to mix evenly, and send the mixed material into a twin-screw extruder to extrude The sheet is discharged and then compacted by a roller press.

[0057] (3) Place the compacted material obtained in the previous step in a crusher for crushing and grading, and control the product D 50 = 20-30μm, the fine powder is put back into the twin-screw extruder to extrude the sheet, and then rolled and compacted; the coarse powder is crushed and classified again.

[0058] (4) Heat treatment is carried out on the material after the classification in the previous step under nitrogen atmosphere, the heat treatment temperature is 800° C., and the holding time is 2 hours.

[0059] (5) D...

Embodiment 2

[0061] (1) Take 1 g of silicon particles with an average particle size of 100 nm, add 20 g of agate to an agate mortar and perform ball milling at a speed of 400 r / min for 5 hours.

[0062] (2) Place the silicon particles after ball milling, artificial graphite (1g) and pitch (0.5g) in a mixer to mix evenly, and send the mixed material into a twin-screw extruder to extrude the sheet, and then pass Roller compaction.

[0063] (3) Place the compacted material obtained in the previous step in a crusher for crushing and grading, and control the product D 50 = 20-30μm, the fine powder is put back into the twin-screw extruder to extrude the sheet, and then rolled and compacted; the coarse powder is crushed and classified again.

[0064] (4) Put the material after the classification in the previous step into a tube furnace, and conduct heat treatment under an argon atmosphere. The heating rate is 5°C / min, the heat treatment temperature is 900°C, and the holding time is 2h.

[0065]...

Embodiment 3

[0067] (1) Take 1 g of silicon particles with an average particle size of 500 nm, add 20 g of agate into an agate mortar and perform ball milling at a speed of 500 r / min for 10 h.

[0068] (2) Place the ball-milled silicon particles, natural flake graphite (1.2g), and polyacrylic acid (0.5g) in a mixer to mix evenly, and send the mixed material into an internal mixer to knead a block , and then compacted by a roller press.

[0069] (3) Place the compacted material obtained in the previous step in a crusher for crushing and grading, and control the product D 50 =15~30μm, the fine powder is re-inserted into the twin-screw extruder to extrude the sheet, and then rolled and compacted; the coarse powder is crushed and classified again.

[0070] (4) Place the graded material obtained in the previous step in a tube furnace, and conduct heat treatment under an argon atmosphere with a heating rate of 5°C / min, a holding temperature of 900°C, and a holding time of 4 hours.

[0071] (5)...

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Abstract

The invention relates to a high-compaction-density lithium ion battery silicon-carbon negative electrode material and a preparation method thereof; the negative electrode material comprises a carbon matrix and silicon particles, wherein the silicon particles are ball milled and activated to be uniformly mixed with the carbon matrix material, and then compaction and forming are carried out on the silicon particles to enable the silicon particles to be uniformly laid in the carbon matrix; next, the oxide on the surface of the silicon particles is removed by acid washing, and gaps are formed between the silicon particles and the carbon matrix. The preparation method comprises the following steps of uniformly mixing the silicon particles with the carbon matrix material after the silicon particles are ball milled and activated, then carrying out compacting and forming, crushing, grading, carbonizing in a protective atmosphere, and washing in a hydrofluoric acid solution. The prepared silicon-carbon composite negative material has the advantages of high compaction density, small specific surface area and high first coulombic efficiency; and the compaction density of the powder body of the silicon-carbon negative electrode material prepared by the preparation method is not lower than 1.6g / cm3, D50 is 10-30 microns, the specific surface area is not higher than 10m2 / g, and the first coulombic efficiency is higher than 85%. The preparation method is simple in process flow, low in cost and suitable for large-scale production.

Description

technical field [0001] The invention relates to a silicon-carbon composite negative electrode material for a lithium-ion battery and a preparation method thereof, in particular to a silicon-carbon negative electrode material with a high compacted density lithium-ion battery and a preparation method thereof. The invention belongs to the field of composite material and electrochemical technology. Background technique [0002] At present, with the development of society and the improvement of people's requirements for high quality of life, new green and environmentally friendly rechargeable batteries have attracted much attention. Lithium-ion batteries, in particular, have seen unprecedented growth in applications ranging from portable electronics to powered vehicles since they were first commercialized in 1990. However, the limited specific capacity of graphite anode limits the development and application of high-performance lithium-ion batteries. [0003] In the research of...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/362H01M4/386H01M4/625H01M4/628H01M10/0525Y02E60/10
Inventor 周昊宸
Owner 湖南宸宇富基新能源科技有限公司
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