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A silicon-carbon composite pole piece, its preparation method and application

A silicon-carbon composite and pole piece technology, applied in electrode manufacturing, battery electrodes, structural parts, etc., can solve the problems of silicon-carbon negative electrode being less safe than graphite negative electrode, reducing the first coulomb efficiency, affecting battery safety, etc. The effect of increasing the transmission rate and improving the first-time efficiency

Active Publication Date: 2022-06-21
SVOLT ENERGY TECHNOLOGY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, in the actual use process, there are many inherent "deficiencies" in the silicon-carbon negative electrode, which are specifically manifested in: during the charging and discharging process, the volume of silicon will expand by 100-300%, and the continuous shrinkage and expansion will cause the powder of the silicon negative electrode material. It will seriously affect the life of the battery; secondly, the continuous expansion of silicon will generate a lot of stress inside the battery, which will squeeze the pole piece, and the pole piece may break after many cycles; and it is also very likely Causes the reduction of the internal porosity of the battery, reduces the movement channel of lithium ions, causes the precipitation of lithium metal, and affects the safety of the battery
In addition, the conductivity of silicon is much worse than that of graphite, which leads to a large degree of irreversibility in the lithium ion intercalation process, thereby reducing its first Coulombic efficiency.
At the same time, due to the improvement of battery energy density, silicon carbon negative electrodes are prone to safety problems caused by excessive instantaneous current, including the above-mentioned problem of lithium analysis caused by silicon expansion, which makes silicon carbon negative electrodes not as safe as graphite negative electrodes.

Method used

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  • A silicon-carbon composite pole piece, its preparation method and application
  • A silicon-carbon composite pole piece, its preparation method and application
  • A silicon-carbon composite pole piece, its preparation method and application

Examples

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Effect test

Embodiment 1

[0060] This embodiment provides a preparation method of a silicon-carbon composite pole piece, and the preparation method includes:

[0061] (1) In the three-electrode system, a foam current collector (30 μm in thickness, 50% porosity) was used as the working electrode, a lithium sheet was used as the counter electrode, and a 0.1 mol / L lithium difluorooxalate solution was used as the electrolyte. Cyclic voltammetry (scanning from -2V to 2V) deposited lithium salts inside and on the surface of the foam current collector for 10 weeks, and after washing and drying, a prelithiated foam current collector was obtained;

[0062] (2) Mix the silicon carbon anode material, CMC, SBR, SP and water uniformly in a mass ratio of 93:1.5:3.5:2:150 to obtain a silicon-oxygen slurry; coat the surface of the pre-lithiated foam current collector 30μm thick silicon-oxygen slurry is dried and rolled to form a silicon-carbon material layer;

[0063] (3) Mix the polyalkylene carbonate, SP and N-meth...

Embodiment 2

[0067] This embodiment provides a preparation method of a silicon-carbon composite pole piece, and the preparation method includes:

[0068] (1) In the three-electrode system, a foam current collector (30 μm in thickness, 50% porosity) was used as the working electrode, a lithium sheet was used as the counter electrode, and a 0.1 mol / L lithium difluorooxalate solution was used as the electrolyte. Cyclic voltammetry (scanning from -2V to 2V) deposited lithium salts inside and on the surface of the foam current collector for 10 weeks, and after washing and drying, a prelithiated foam current collector was obtained;

[0069] (2) Mix the silicon carbon anode material, CMC, SBR, SP and water uniformly in a mass ratio of 93:1.5:3.5:2:150 to obtain a silicon-oxygen slurry; coat the surface of the pre-lithiated foam current collector 20μm thick silicon-oxygen slurry is dried and rolled to form a silicon-carbon material layer;

[0070] (3) Mix the polyalkylene oxide, SP and N-methylpy...

Embodiment 3

[0073] This embodiment provides a preparation method of a silicon-carbon composite pole piece, and the preparation method includes:

[0074] (1) In the three-electrode system, a foam current collector (30 μm in thickness, 50% porosity) was used as the working electrode, a lithium sheet was used as the counter electrode, and a 0.1 mol / L lithium difluorooxalate solution was used as the electrolyte. Cyclic voltammetry (scanning from -2V to 2V) deposited lithium salts inside and on the surface of the foam current collector for 10 weeks, and after washing and drying, a prelithiated foam current collector was obtained;

[0075] (2) Mix the silicon carbon anode material, CMC, SBR, SP and water uniformly in a mass ratio of 93:1.5:3.5:2:150 to obtain a silicon-oxygen slurry; coat the surface of the pre-lithiated foam current collector 50μm thick silicon-oxygen slurry is dried and rolled to form a silicon-carbon material layer;

[0076] (3) Mix the polyalkyl acrylate, SP and N-methylpyrr...

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Abstract

The invention provides a silicon-carbon composite pole piece, its preparation method and application. The silicon-carbon composite pole piece includes a pre-lithiated foam current collector, and the surface of the pre-lithiated foam current collector is sequentially stacked with silicon carbon. Material layer, organic polymer layer and graphene layer; said pre-lithiated foam current collector includes foam current collector and lithium salt compound deposited on its surface and inside. The present invention improves the first-time efficiency of silicon carbon through pre-lithiation of foam current collectors, and coating organic polymers between pole pieces to improve storage performance, and graphene in the outer layer improves rate performance and processing performance.

Description

technical field [0001] The invention belongs to the technical field of preparation of negative electrode materials, and relates to a silicon-carbon composite pole piece, a preparation method and application thereof. Background technique [0002] At present, the negative electrodes of commercial lithium-ion batteries mainly use carbonaceous materials such as natural graphite and artificial graphite, and their theoretical capacity is only 372mAh / g, which is relatively low. The theoretical gram capacity of graphite negative electrodes is 372mAh / g. Using the joint efforts of the two systems, the current gram capacity of the graphite negative electrode in the full battery has reached 355mAh / g, reaching more than 95% of the theoretical value, and the application of the graphite negative electrode is approaching the limit. It can no longer meet the requirements of high-energy cathode materials such as lithium-rich materials and nickel-manganese spinel high-voltage materials, nor ca...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/134H01M4/133H01M4/62H01M4/1395H01M4/1393H01M4/04H01M10/052H01M10/0525
CPCY02E60/10
Inventor 赵晓锋
Owner SVOLT ENERGY TECHNOLOGY CO LTD
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