Silicon-carbon composite lithium ion battery negative electrode material and preparation method thereof

A technology for lithium-ion batteries and negative electrode materials, applied in battery electrodes, negative electrodes, secondary batteries, etc., can solve problems such as not being able to buffer volume expansion well, affecting material cycle performance, and nano-silicon shedding, so as to increase service life , The effect of compact particles and high tap density

Active Publication Date: 2020-01-17
SHAANXI COAL & CHEM TECH INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in this patent document, the coating agent asphalt is first mixed with the spray material, and then fused and shaped, which causes part of the nano-silicon coated on the surface of the carbon substrate to fall off and agglomerate, which affects the cycle performance of the material.
At the same time, nano-silicon is only dispersed on the surface of the carbon matrix in this method, which cannot buffer the volume expansion well, so that the expansion of the material is still very large in practical applications.

Method used

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  • Silicon-carbon composite lithium ion battery negative electrode material and preparation method thereof
  • Silicon-carbon composite lithium ion battery negative electrode material and preparation method thereof
  • Silicon-carbon composite lithium ion battery negative electrode material and preparation method thereof

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preparation example Construction

[0032] A method for preparing a silicon-carbon composite lithium-ion battery negative electrode material according to the present invention comprises the following steps:

[0033] Step 1, adding micro-silicon and dispersant into the solvent, and grinding to obtain nano-silicon slurry 1;

[0034] Step 2, adding the carbon matrix to the nano-silicon slurry 1, and stirring to obtain a mixed slurry 2; wherein the carbon matrix is ​​one of flattened artificial graphite, flattened natural graphite, and flattened mesophase carbon microspheres or Several;

[0035] Step 3, drying the mixed slurry 2 to obtain a precursor material 1; adding the precursor material 1 to a fusion machine for fusion to obtain a precursor material 2; mixing the precursor material 2 with a coating agent to obtain a precursor material 3;

[0036] Step 4, granulating the precursor material 3 to obtain a precursor material 4, placing the precursor material 4 in a protective atmosphere for heat treatment to obtai...

Embodiment 1

[0049] Disperse 500g of silicon powder with a median particle size of 5μm into 10000g of ethanol solvent, then add 5g of polyvinylpyrrolidone, and finally add it into a ball mill to obtain a nano-silicon slurry with a median particle size of 120nm, and obtain slurry 1; Flattened natural graphite with a particle size of 8-12 μm is added to the above nano-silicon slurry to obtain a mixed slurry 2; the slurry 2 is spray-dried to obtain a precursor material 1; the precursor material 1 is added to a fusion machine for fusion and shaping to obtain Precursor material 2, fusion machine knife spacing 0.1mm, rotating speed 850rpm / min, fusion time 15min; add precursor material 2 and 500g (25% of precursor material 3) coal tar pitch into VC mixer and mix to obtain precursor material 3 ; Place the precursor material 3 in a molding machine and press it into a block to obtain the precursor material 4, and then place it in a box furnace. In a nitrogen atmosphere, first heat it to 300°C and kee...

Embodiment 2

[0051] Disperse 1,000g of silicon powder with a median particle size of 3 μm into 25,000g of ethylene glycol solvent, add 10g of polyvinyl acid, and finally add it to a ball mill for ball milling to obtain a nano-silicon slurry with a median particle size of 120nm to obtain slurry 1; Flat artificial graphite with a median particle size of 5-8 μm is added to the above nano-silicon slurry to obtain a mixed slurry 2; the slurry 2 is spray-dried to obtain a precursor material 1; the precursor material 1 is added to a fusion machine for fusion shaping , to obtain precursor material 2, fusion machine knife spacing 1mm, rotating speed 400rpm / min, fusion time 30min; add precursor material 2 and 800g (20% of precursor material 3) petroleum asphalt into VC mixer and mix to obtain precursor material 3. Place the precursor material 3 in a double-roll machine and press it into a block to obtain the precursor material 4, and then place it in a box furnace. In an argon atmosphere, first heat ...

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Abstract

The invention provides a silicon-carbon composite lithium ion battery negative electrode material and a preparation method thereof. The preparation method comprises the following steps of adding micron silicon and a dispersing agent into a solvent, and grinding to obtain nano silicon slurry 1; adding a carbon matrix into the nano silicon slurry 1, and stirring to obtain mixed slurry 2, wherein thecarbon matrix is one or more of flattened artificial graphite, flattened natural graphite and flattened mesocarbon microbeads; and drying the mixed slurry 2, adding into a fusion machine for fusion,mixing with a coating agent, granulating, carrying out heat treatment in a protective atmosphere, carrying out high-temperature carbonization treatment in the protective atmosphere, crushing, gradingand demagnetizing to obtain the silicon-carbon composite negative electrode material. According to the present invention, the structure with better volume expansion can be buffered, the dispersion andcomplete coating of the nano silicon on the carbon matrix are realized, and the direct contact between the nano silicon and the electrolyte is isolated, so that the composite material can form a stable SEI film, and the service life of the battery is greatly prolonged.

Description

technical field [0001] The invention belongs to the field of lithium ion battery negative electrode materials, and relates to a silicon-carbon composite lithium ion battery negative electrode material and a preparation method thereof. Background technique [0002] At present, graphite-like carbon materials are the main materials used in the negative electrode of lithium-ion batteries, including artificial graphite, natural graphite, soft carbon, hard carbon, etc. However, these materials have a low specific capacity (<372mAh / g) during charge and discharge, which cannot meet the development requirements of batteries for energy density. Among many anode materials that have the potential to replace graphite, silicon has become a key research object because of its high specific capacity (theoretical specific capacity is 4200mAh / g), and its voltage platform is slightly higher than that of graphite anode, and it is not easy to decompose lithium during charging. , has good safe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/625H01M4/628H01M10/0525H01M2004/021H01M2004/027Y02E60/10
Inventor 曹新龙田占元曹国林邵乐范瑞娟杨时峰
Owner SHAANXI COAL & CHEM TECH INST
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