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A carbon-silicon composite material, its preparation method and a lithium-ion battery comprising the composite material

A composite material and carbon-silicon composite technology, applied in the field of lithium-ion batteries, can solve the problems of high first efficiency, low value, and difficulty in guaranteeing

Active Publication Date: 2021-01-08
深圳市贝特瑞新能源技术研究院有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the structure of this material is difficult to guarantee a high first effect, and the cost is relatively high in practical applications.
[0006] For example, patent CN103618074A discloses a method of embedding nano-silicon with polymer microspheres to improve the dispersion of nano-silicon in silicon-carbon composite negative electrode materials, thereby alleviating the volume effect of silicon during lithium intercalation and improving its cycle performance, but the patent The published preparation method has many procedures and cumbersome process, and the value of practical application is not high

Method used

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  • A carbon-silicon composite material, its preparation method and a lithium-ion battery comprising the composite material
  • A carbon-silicon composite material, its preparation method and a lithium-ion battery comprising the composite material
  • A carbon-silicon composite material, its preparation method and a lithium-ion battery comprising the composite material

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Experimental program
Comparison scheme
Effect test

preparation example Construction

[0088] The specific preparation method of the cylindrical battery is as follows: the negative electrode material, the conductive agent and the binder are dissolved and mixed in the solvent according to the mass percentage of 94:1:5, and the solid content is controlled at 50%, and coated on the copper foil current collector Then, the ternary positive pole piece prepared by traditional mature technology, 1mol / L LiPF6 / EC+DMC+EMC (v / v=1:1:1) electrolyte, Celgard 2400 separators and casings are assembled with 18650 cylindrical single cells using conventional production processes.

[0089] Test the charging and discharging performance and first effect of the battery under the test conditions of charging and charging: Among them, the charging and charging test conditions are: first discharge in the way of CC+CV (that is, first constant current and then constant voltage), and then charge in the way of CC (constant current), and the constant current rate during charging and discharging...

Embodiment 1

[0093] (1) Surface modification: Use a binder to modify the surface of amorphous carbon by solid-phase modification. Specifically, accurately weigh 47.6g of high-temperature pitch and 456.4g of soft carbon, and mix them in a VC mixer for 30 minutes , The speed of the VC mixer is 3000r / min. Then, put the obtained material into the fusion machine, and fuse it for 45 minutes. The rotation speed of the fusion machine is 3000r / min, and obtain the soft carbon modified by high temperature pitch, which is marked as SC@LQ;

[0094] (2) Composite: adding nano-silica powder and dispersant to isopropanol, high-energy ball milling, the ball milling condition is 300r / min, ball milling 24h, to obtain silicon slurry. Accurately weigh the silicon slurry (converted to 2.8 g of silicon, the solvent is isopropanol), ultrasonically disperse for 30 min, and set aside. Under the condition of stirring at room temperature, 36.0 g of high-temperature pitch-modified soft carbon (SC@LQ) was added to the...

Embodiment 2

[0108] (1) Surface modification: Use a binder to modify the surface of amorphous carbon by the liquid phase modification method, accurately weigh 3.4g of high-temperature pitch, and add the high-temperature pitch to 100mL of tetrahydrofuran (THF) solution under the condition of magnetic stirring at room temperature , and stirred for 1 hour to obtain a THF solution of asphalt. Add 32.6 g of soft carbon to the THF solution of asphalt, heat and evaporate the solvent to obtain a soft carbon modified with high-temperature pitch.

[0109] (2) Composite: adding nano-silica powder and dispersant to isopropanol, high-energy ball milling, the ball milling condition is 300r / min, ball milling 24h, and silicon slurry solution is obtained. Add the high-temperature pitch-modified soft carbon obtained in step (1) and the silicon slurry after ultrasonic dispersion for 1 hour (converted to 2.8 g of silicon, and the solvent is isopropanol) into 80 mL of isopropanol solvent, and stir at room tempe...

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Abstract

The invention discloses a carbon-silicon composite material and a preparation method of the carbon-silicon composite material as well as a lithium-ion battery comprising the composite material. The carbon-silicon composite material comprises an amorphous carbon inner core and a shell which is formed by dispersing nano silicon into a pyrolytic carbon layer. The method is simple and easy to operate, is environmental-friendly and is suitable for large-scale production; the prepared carbon-silicon composite material has a stable structure, the nano silicon has good dispersibility and the coated degree of the nano silicon is very high; the carbon-silicon composite material is used as a negative electrode material of the lithium-ion battery and has a very high lithium removing specific capacity, a good circulating performance and an excellent rapid charging property; the lithium removing specific capacity is 391.7mAh / g or more, the capacity retention rate is 95.3 percent or more after the lithium-ion battery is charged and discharged at constant current of 1.0C for 50 times, and the charging rate of 10min can reach 90.2 percent.

Description

technical field [0001] The invention belongs to the technical field of electrochemistry and lithium-ion battery negative electrode materials, and relates to a composite material, a preparation method thereof and a lithium-ion battery containing the composite material, in particular to a carbon-silicon composite material, a preparation method thereof, and a carbon-silicon composite material containing the carbon-silicon composite material. Silicon composite materials as negative electrode materials for lithium-ion batteries. Background technique [0002] The rate performance and low temperature performance of traditional graphite materials are poor, and the theoretical capacity is only 372mAh / g, which limits its application in the field of power batteries. Amorphous (soft carbon, hard carbon) has relatively excellent rate, cycle, and low temperature performance, and is one of the ideal materials for preparing power batteries. Its disadvantage is that the specific capacity of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/386H01M4/587H01M4/621H01M4/622H01M4/625H01M4/628H01M10/0525H01M2220/20Y02E60/10
Inventor 程钢汪福明任建国岳敏
Owner 深圳市贝特瑞新能源技术研究院有限公司
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