A silicon-based composite negative electrode material and its preparation method and application

A negative electrode material, silicon-based technology, applied in the field of silicon-based composite negative electrode material and its preparation, can solve the problems of restricting the migration rate of lithium ions, loss of electrochemical connection of active materials, low electrical conductivity, etc., and achieves insignificant volume expansion effect. Good cycle stability, the effect of reducing production costs

Active Publication Date: 2021-11-19
SHENZHEN DYNANONIC
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] Due to the advantages of high energy density, long cycle life, and environmental friendliness, lithium-ion batteries are widely used in portable electronic products such as mobile phones and notebook computers, new energy vehicles, and energy storage fields. The negative electrode material of the battery is graphite-based carbon material, but graphite-based carbon material has problems such as low theoretical capacity, poor compatibility with solvents, and poor high-rate discharge performance; therefore, it has the advantages of high capacity, high safety, and wide source of raw materials. Silicon-based materials used as negative electrode active materials have become an important research direction to improve the energy density of lithium-ion batteries.
[0003] However, the above-mentioned silicon-based negative electrode materials will have a large volume expansion during the charge and discharge process, which will cause problems such as powdering and falling off during the charge and discharge process, and the electrochemical connection between the active materials and the current collector will be lost; At the same time, it will also make the silicon-based negative electrode material unable to form a stable surface solid electrolyte film (ie SEI film) in the electrolyte. After the electrode structure is destroyed, the newly exposed silicon surface will form a new SEI film again, which will further lead to capacity fading, cycle reduction
In addition, the intrinsic conductivity of silicon is low, which restricts the migration rate of lithium ions, resulting in poor material rate performance.

Method used

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  • A silicon-based composite negative electrode material and its preparation method and application
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  • A silicon-based composite negative electrode material and its preparation method and application

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[0054] see figure 1 , one embodiment of the present invention provides a method for preparing a silicon-based composite negative electrode material, comprising the following steps:

[0055] S01, corroding silicon oxide particles to obtain silicon oxide with a porous structure;

[0056] S02. In the presence of a catalyst, carbon nanotubes are grown in situ on the surface and in the pores of the silicon oxide with a porous structure, and then pickled to remove the catalyst; wherein, the catalyst and the porous structure The mass ratio of silicon oxide is 1:(10-1000), and the aspect ratio of the carbon nanotubes is not less than 3000;

[0057] S03, carbon-coating the material obtained in step S02 by chemical vapor deposition to form a first coating layer;

[0058] S04, prepare the material obtained in step S03 with graphite, conductive agent, binder, and solvent to form a mixed slurry; spray-dry and granulate the mixed slurry, and form an embedded material outside the first coa...

Embodiment 1

[0062] A method for preparing a silicon-based composite negative electrode material, comprising the following steps:

[0063] (1) Take amorphous silicon oxide with an average particle size D50 of 5 μm and add it to a hydrofluoric acid solution with a mass concentration of 10%, and carry out corrosion reaction for 1 hour while stirring with ultrasonic waves. After the corrosion is completed, filter the reaction mixture with suction , and the solid obtained by suction filtration was washed with pure water until the pH of the washing liquid was 7, and then dried in an oven at 110°C to obtain a porous silicon-based matrix, that is, silicon oxide with a porous structure;

[0064] (2) The iron powder with a particle size of 150nm and the above-mentioned porous silicon-based substrate are mechanically fused according to a mass ratio of 1:99, the fusion machine speed is 4500rpm, and the fusion time is 10min, so that the iron powder is evenly distributed on the surface of the porous sil...

Embodiment 2

[0070] A method for preparing a silicon-based composite negative electrode material, comprising the following steps:

[0071](1) Take amorphous silicon oxide with an average particle size D50 of 5 μm and add it to a hydrofluoric acid solution with a mass concentration of 20%, and carry out corrosion reaction for 0.5 h while stirring with ultrasonic waves. After the corrosion is completed, pump the reaction mixture The solid obtained by suction filtration was washed with pure water until the pH of the washing solution was 7, and then dried in an oven at 110°C to obtain a porous silicon-based matrix, that is, silicon oxide with a porous structure.

[0072] (2) According to the mass ratio of 3:97, the catalyst with a particle size of 100nm (specifically, a mixture of iron powder and nickel powder) is mechanically fused with the above-mentioned porous silicon-based substrate. The fusion machine speed is 3500rpm, and the fusion time is 20min. The catalyst powder is evenly distribut...

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Abstract

The invention provides a method for preparing a silicon-based composite negative electrode material, comprising the following steps: (1) corroding silicon oxide particles to obtain silicon oxide with a porous structure; (2) in the presence of a catalyst, in the In-situ growth of carbon nanotubes on the surface and pores of silicon oxide with a porous structure; (3) carbon-coating the material obtained in step (2) by chemical vapor deposition to form a first coating layer; (4) The material obtained in step (3) is prepared into a mixed slurry with graphite, conductive agent, binder, and solvent, and the mixed slurry is spray-dried and granulated to form a second coating outside the first coating layer. cladding. The preparation method has simple process and low cost, and can be used in industrialized production; meanwhile, the obtained silicon-based composite negative electrode material has good conductivity and cycle stability. The invention also provides a silicon-based composite negative electrode material and its application.

Description

technical field [0001] The invention relates to the field of lithium ion battery materials, in particular to a silicon-based composite negative electrode material and a preparation method and application thereof. Background technique [0002] Due to the advantages of high energy density, long cycle life and environmental friendliness, lithium-ion batteries are widely used in portable electronic products such as mobile phones and notebook computers, new energy vehicles, and energy storage fields. The negative electrode material of the battery is graphite-based carbon material, but graphite-based carbon material has problems such as low theoretical capacity, poor compatibility with solvents, and poor high-rate discharge performance; therefore, it has the advantages of high capacity, high safety, and wide source of raw materials. Silicon-based materials used as negative electrode active materials have become an important research direction to improve the energy density of lithi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/587H01M4/62H01M10/0525
CPCH01M4/364H01M4/386H01M4/587H01M4/625H01M10/0525H01M2004/027Y02E60/10
Inventor 朱成奔万远鑫孔令涌任望保钟泽钦
Owner SHENZHEN DYNANONIC
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