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Silicon-carbon composite material for secondary lithium battery and preparation method thereof

A technology of silicon-carbon composite materials and secondary lithium batteries, which is applied in the direction of secondary batteries, battery electrodes, circuits, etc., can solve the problems of unrealized and high technical barriers, and achieve the goal of improving material performance, improving cycle performance, and reducing new surface Effect

Pending Publication Date: 2021-12-21
LANXI ZHIDE ADVANCED MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Practice has proved that in order to obtain ideal electrochemical performance, the particle size of silicon particles in composite materials should not exceed 200-300nm, but the technical barriers to key indicators such as specific surface area, particle size distribution, impurities, and surface passivation layer thickness High, not yet implemented

Method used

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  • Silicon-carbon composite material for secondary lithium battery and preparation method thereof
  • Silicon-carbon composite material for secondary lithium battery and preparation method thereof
  • Silicon-carbon composite material for secondary lithium battery and preparation method thereof

Examples

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preparation example Construction

[0030] The preparation method provided by the present invention includes the following steps: a precursor step, a first coating layer coating step, a pre-lithiation step, and a second coating layer coating step;

[0031] The precursor process refers to chemical vapor deposition of silicon raw materials to obtain SiO x (0<x<2) precursor;

[0032] The first cladding layer cladding process refers to the SiO by chemical vapor deposition x Precursor or lithium-doped active particles are coated with conductive layer;

[0033] The pre-lithiation process refers to inserting lithium into the aforementioned coated material to generate lithium silicate inside the silicon oxide compound to obtain lithium-doped active particles;

[0034] The second coating layer coating process refers to SiO x The precursor or lithium-doped active particles are mixed with the ion-enhanced phase and the ion matrix, and evenly dispersed in pure water, and then the mixed solution is filtered and dried to c...

Embodiment 1

[0043] A certain amount of Si powder and SiO 2 Mix the powder evenly, put it into a vacuum furnace for heat treatment, and heat it to 1200°C under the condition of 500Pa vacuum degree, and the heat treatment time is 1h. 1~10um silicon oxide precursor particles.

[0044] Evenly disperse the particles obtained above into pure water, then add 1% CNT (carbon nanotubes) by mass fraction, continue to stir evenly, filter and dry to obtain silicon sub-silicon particles with CNT attached to the surface, and then the particles obtained in the previous step Load it into a CVD furnace, heat it to 950°C, and feed acetylene with a flow rate of 9L / min, hydrogen gas with a flow rate of 9L / min and argon gas with a flow rate of 18L / min, and the deposition time is 1h. Acetylene is decomposed at high temperature to form pyrolytic carbon coated on the surface of CNT and particles to obtain the first coating layer. The cladding layer is a carbon composite material, wherein CNT is a reinforcing ph...

Embodiment 2

[0048] Follow the same method as in Preparation Example 1, except that the ion-conducting layer (second coating layer) is coated first, and then the conductive layer (first coating layer) is coated.

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Abstract

The invention discloses a silicon-carbon composite material for a secondary lithium battery and a preparation method thereof. The silicon-carbon composite material for the secondary lithium battery comprises an inner core containing a silicon-based material, a first coating layer and a second coating layer, wherein the first coating layer is a conducting layer, the second coating layer is an ion conducting layer, and the first coating layer and the second coating layer are not sequentially defined. According to the silicon-carbon composite material provided by the invention, the coating layer is the composite material, and the electric conduction (or ion conduction) capability of a base material and the reinforcing and toughening properties of a reinforcing phase are combined, so that the material has very strong anti-expansion capability. In the secondary battery, the coating layer which is not easy to crack means fewer new surfaces, so that the electrolyte consumption is reduced, and the cycle performance of the battery is improved. In addition, the preparation method is simple, easy to implement and suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to the field of lithium-ion battery materials, in particular to a silicon-carbon negative electrode material for a secondary lithium battery and a preparation method thereof. Background technique [0002] In recent years, the replacement of carbon materials by silicon-based materials as anode materials for lithium-ion batteries has become a research hotspot in academia and industry. However, the volume expansion effect of silicon in the lithium alloying process is particularly serious, which will lead to serious pulverization of electrode materials. The collapse of the electrode structure and the loss of electrical contact between the active material and the current collector lead to poor cycle performance of the battery. The problem of volume expansion can be solved by controlling the content of silicon in carbon materials, reducing the volume of silicon to the nanometer level; or changing the texture and shape of graphite to ach...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/366H01M4/386H01M4/625H01M10/0525H01M4/62Y02E60/10H01M4/364H01M4/587H01M2004/027C01B33/113C01P2004/80C01B33/32C01B32/168C01B32/05H01M4/485C01B33/183C01P2002/72C01P2006/40H01M4/622
Inventor 陈青华胡盼姚林林房冰
Owner LANXI ZHIDE ADVANCED MATERIALS CO LTD
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