High-performance silicon-carbon composite negative electrode material with adjustable and controllable particle size and preparation method thereof

A silicon-carbon composite and negative electrode material technology, applied in the direction of negative electrodes, active material electrodes, battery electrodes, etc., can solve the problem of electrochemical indicators, particle structure, morphology, and particle size that affect the capacity, rate, and cycle performance of lithium-ion batteries. Poor performance, poor dispersion effect and poor electronic conductivity, etc., to ensure consistent particle size, improve cycle stability, and reduce production and processing costs

Inactive Publication Date: 2020-03-27
CHENGDU EMINENT NEW ENERGY TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because the carbon layer coated on the surface of nano-silicon is prone to uneven coating, resulting in poor particle structure, morphology, and particle size consistency

Method used

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  • High-performance silicon-carbon composite negative electrode material with adjustable and controllable particle size and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0017] Example 1

[0018] A high-performance silicon-carbon composite negative electrode material with adjustable particle size, comprising an inner core and a coating layer covering the outer core. The core is nano-silicon, and the coating layer includes The first carbon coating layer and the second carbon coating layer, the hardness of the first carbon coating layer is less than the hardness of the second carbon coating layer.

[0019] Specifically, the nano silicon can be one or more of high-purity silicon powder, polycrystalline silicon powder or single crystal silicon powder, with a particle size D50=50-250nm. The first carbon coating layer is made by low-temperature carbonization of pitch or paraffin, the softening point of the pitch is 80-280° C., and the particle size D50 is 1-10 μm; the second carbon coating layer is made by high-temperature carbonization of an organic carbon source. Among them, the organic carbon source is one or more of phenol resin, epoxy resin, urea r...

Example Embodiment

[0028] Example 2

[0029] S1: Mix the nano silicon with a medium particle size of D50=150nm and the asphalt with a softening point of 250°C according to a mass ratio of 100:50 in a high-speed mixer, and then disperse the mixed powder with ethanol to obtain a mixed slurry;

[0030] S2: Place the mixed slurry in a ball mill for grinding, and grind for 1 hour at a rotation speed of 1000r / min. The resulting mixed slurry is vacuum freeze-dried at -20°C to obtain a composite powder with organic carbon source coated nano silicon powder body;

[0031] S3: Place the composite powder in a fusion device with a rotation speed of 300r / min for 25 minutes at low speed to obtain a composite coating with a high degree of spheroidization;

[0032] S4: Put the composite coating into a tube furnace, raise the temperature to 600°C at 3°C / min and carbonize it for 2 hours, and pass through a 200-mesh screen after cooling to obtain a composite precursor;

[0033] S5: Mix the composite precursor with 5% hard c...

Example Embodiment

[0035] Example 3

[0036] S1: Mix the nano silicon with a medium particle size of D50=150nm and the asphalt with a softening point of 250°C according to a mass ratio of 100:50 in a high-speed mixer, and then disperse the mixed powder with ethanol to obtain a mixed slurry;

[0037] S2: Place the mixed slurry in a ball mill for grinding, and grind for 4 hours at a speed of 1000r / min. The resulting mixed slurry is vacuum freeze-dried at -20°C to obtain a composite powder with organic carbon source coated nano silicon powder body;

[0038] S3: Place the composite powder in a fusion device with a rotation speed of 300r / min for 25min at low speed to obtain a composite coating with a high degree of spheroidization;

[0039] S4: Put the composite coating into a tube furnace, raise the temperature to 600°C at 3°C / min and carbonize it for 2 hours, and pass through a 200-mesh screen after cooling to obtain a composite precursor;

[0040] S5: Mix the composite precursor with 5% hard carbon coating...

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Abstract

The invention discloses a high-performance silicon-carbon composite negative electrode material with adjustable and controllable particle size and a preparation method thereof. The negative electrodematerial comprises an inner core and a coating layer coating the inner core, the inner core is nanometer silicon, the coating layer comprises a first carbon coating layer and a second carbon coatinglayer which are sequentially arranged from inside to outside, and the hardness of the first carbon coating layer is smaller than that of the second carbon coating layer. The two carbon coating layersare coated outside the nano silicon, the first carbon coating layer is softer, is more uniform after being coated by adopting a low-temperature carbonization process, has a stable structure, is not easy to damage, and can effectively relieve the volume expansion of the nano silicon; the particle size uniformity is good, and the cycling stability of the material can be improved. The second carbon coating layer on the outermost layer is hard, particle bonding of the composite material during high-temperature carbonization can be prevented, the particle size consistency of the composite materialis guaranteed, meanwhile, the material yield can be increased, the production and processing cost is reduced, and large-scale production is easy to achieve.

Description

technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a silicon-carbon composite negative electrode material with high performance and adjustable particle size and a preparation method thereof. Background technique [0002] Due to the advantages of high voltage, high capacity, long cycle life, low self-discharge efficiency, and good safety performance, lithium-ion batteries are widely used in 3C / digital products, electric vehicles, start-stop power supplies, aircraft models, and energy storage. At present, commercial lithium-ion battery anode materials are still mainly graphite materials. The theoretical specific capacity of graphite is 372mAh / g, but the high-end graphite sold on the market is already close to this theoretical capacity, which cannot meet the requirements of higher energy for lithium-ion batteries. Density requirements, its future development space is very limited. Therefore, it is imperative to develop a new ge...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M10/0525
CPCH01M4/362H01M4/386H01M4/587H01M10/0525H01M2004/027Y02E60/10
Inventor 平国政王圆方梁运辉高川乔乔王刚
Owner CHENGDU EMINENT NEW ENERGY TECH CO LTD
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