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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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  • Application Information

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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, poor dispersion effect, and poor electronic conductivity, which seriously affect the capacity, rate, and cycle performance of lithium-ion batteries. Chemical indicators

Method used

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

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Experimental program
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Effect test

Embodiment 1

[0018] A silicon-carbon composite anode material with high performance and adjustable particle size, including an inner core and a coating layer coated outside the inner core, the inner core is nano-silicon, and the coating layer is arranged sequentially from the inside to the outside. A first carbon coating layer and a second carbon coating layer, the hardness of the first carbon coating layer is less than that of the second carbon coating layer.

[0019] Specifically, one or more of high-purity silicon powder, polycrystalline silicon powder or monocrystalline silicon powder can be used for nano-silicon, and the particle size D50=50-250nm. The first carbon coating layer is obtained by low-temperature carbonization of pitch or paraffin, the softening point of the pitch is 80-280°C, and the particle size D50=1-10 μm; the second carbon coating layer is obtained by high-temperature carbonization of organic carbon sources. Wherein, the organic carbon source is one or more of pheno...

Embodiment 2

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

[0030] S2: Put the mixed slurry in a ball mill and grind it for 1 hour at a rotational speed of 1000r / min, and vacuum freeze-dry the obtained mixed slurry at -20°C to obtain a composite powder of organic carbon source-coated nano-silicon powder body;

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

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

[0033] S5: Mix the composite precursor with 5% hard carbon coating amount and phenolic resin in ...

Embodiment 3

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

[0037] S2: Put the mixed slurry in a ball mill and grind it for 4 hours at a rotational speed of 1000r / min, and vacuum freeze-dry the obtained mixed slurry at -20°C to obtain a composite powder of organic carbon source-coated nano-silicon powder body;

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

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

[0040] S5: Mix the composite precursor with 5% hard carbon coating amount and phenolic resin in...

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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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