Lithium ion battery negative electrode active material, preparation method thereof, negative electrode and lithium ion battery comprising negative electrode

A negative electrode active material and lithium-ion battery technology, applied in battery electrodes, secondary batteries, circuits, etc., can solve the problems of poor battery cycle performance, unsuitable for practical use, and increased expansion of pole pieces

Inactive Publication Date: 2017-10-24
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] In the prior art, as the negative electrode active material of lithium-ion batteries, the actual capacity of graphite is close to the theoretical value of 372 mAh/g, but it still cannot meet the high requirements of power battery specific capacity and energy density; while the theoretical capacity of silicon is as high as 4212 mAh /g, so it has received extensive attention in the field of lithium-ion batteries in recent years; the lithium intercalation mechanism of silicon is an alloying mechanism, and its theoretical capacity is calculated in the final lithium intercalation state (Li 22 Si 5 ) when the volume expansion is 400% of the original. Due to the volume expansion problem, when used as a negative electrode active material, it will seriously cause the powdering and fragmentation of the negative electrode material, and at the same time, the SEI film on the surface of the negative electrode will also be destroyed and regenerated. Eventually, the expansion of the pole piece will be further increased, resulting in a significant decline in the electr...

Method used

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  • Lithium ion battery negative electrode active material, preparation method thereof, negative electrode and lithium ion battery comprising negative electrode

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preparation example Construction

[0022] The present invention also proposes a preparation method of the negative electrode active material of lithium ion battery, comprising:

[0023] (1) Mix and disperse the carbon source precursor, lithium-silicon alloy particle powder and organic solvent to obtain a slurry;

[0024] (2) Drying the slurry in step (1) to remove the organic solvent to obtain a precursor of carbon source precursor coated lithium-silicon alloy particles.

[0025] (3) Sintering the precursor in step (2) under an inert atmosphere to obtain a lithium-ion battery negative electrode active material whose core is lithium-silicon alloy particles and whose shell is a carbon layer.

[0026] Preferably, in the step (1), the mass ratio of the carbon source precursor to the lithium-silicon alloy particle powder is 5:1-20:1. By controlling the mass ratio of the carbon source precursor to the lithium-silicon alloy particles, the thickness of the carbon shell coated on the surface of the lithium-silicon allo...

Embodiment 1

[0048] (1) Get 10g polyacrylonitrile and dissolve in the dimethylformamide of 100ml, form the solution of 100g / L, get the lithium-silicon alloy particle powder (in the lithium-silicon alloy particle powder, the weight of lithium in the lithium-silicon alloy particle powder of 1000nm) of 2g mean particle size ratio of 44%), under electromagnetic stirring, the lithium-silicon alloy particles were dropped into the above solution, stirred evenly and ultrasonically dispersed to obtain a slurry;

[0049] (2) placing the slurry in step (1) under an argon protective atmosphere and spray-drying at 80° C. to obtain a carbon source precursor-coated lithium-silicon alloy particle precursor;

[0050] (3) Place the precursor in step (2) in a graphite dry crucible, keep it warm at 800°C for 6 hours under an argon protective atmosphere, and obtain a lithium-ion battery negative electrode with lithium-silicon alloy particles as the core and carbon layer as the shell after cooling Active materi...

Embodiment 2

[0053] The same method as in Example 1 was used to prepare the lithium-ion battery negative active material nuclear battery, except that in step (1) 10 g of polyvinyl alcohol was added instead of polyacrylonitrile to prepare negative active material A2 and battery S2.

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Abstract

The invention proposes a lithium ion battery negative electrode active material, a preparation method thereof, a negative electrode and a lithium ion battery comprising the negative electrode. The negative electrode active material is of a core-shell structure, wherein the core comprises lithium silicon alloy particles, and the shell is a carbon layer. In the negative electrode active material employing the core-shell structure of which the core is the lithium silicon alloy particles and the shell is the carbon layer, the volume expansion effect of silicon used as the negative electrode can be effectively reduced; and when the negative electrode is applied to the battery, relatively high capacity of the obtained battery can be maintained, and meanwhile, the battery also has good cycle property.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery negative electrode active material, a preparation method thereof, a negative electrode and a lithium ion battery containing the negative electrode. Background technique [0002] In the prior art, as the negative electrode active material of lithium-ion batteries, the actual capacity of graphite is close to the theoretical value of 372 mAh / g, but it still cannot meet the high requirements of power battery specific capacity and energy density; while the theoretical capacity of silicon is as high as 4212 mAh / g, so it has received extensive attention in the field of lithium-ion batteries in recent years; the lithium intercalation mechanism of silicon is an alloying mechanism, and its theoretical capacity is calculated in the final lithium intercalation state (Li 22 Si 5 ) when the volume expansion is 400% of the original. Due to the volume expans...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525H01M4/134
CPCH01M4/134H01M4/366H01M4/382H01M4/386H01M4/62H01M10/0525H01M2004/021Y02E60/10
Inventor 孙华军沈菊林赵瑞兰张磊钟毅
Owner BYD CO LTD
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