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Silicon-based electrode with adjustable pore structure and preparation method of silicon-based electrode

A pore structure, silicon-based technology, applied in electrode manufacturing, electrode rolling/calendering, battery electrodes, etc., can solve the problems of poor mechanical stability of electrodes, achieve low price, buffer volume change, and improve cycle stability.

Active Publication Date: 2018-11-06
CHINA AUTOMOTIVE BATTERY RES INST CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The present invention aims at the problem of poor mechanical stability of the electrode in the charging and discharging process of the high specific capacity silicon-based negative electrode in the prior art, and proposes a silicon-based electrode with adjustable pore structure, and selects a binder with high-strength bonding properties, through The development of electrode formula and process, construct a high-capacity silicon-based negative electrode with variable pore structure, and realize the cycle stability of high specific capacity silicon-based negative electrode

Method used

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  • Silicon-based electrode with adjustable pore structure and preparation method of silicon-based electrode
  • Silicon-based electrode with adjustable pore structure and preparation method of silicon-based electrode
  • Silicon-based electrode with adjustable pore structure and preparation method of silicon-based electrode

Examples

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Embodiment 1

[0041] In this example, the active material used in the preparation of raw materials is 81% commercial high-capacity silicon-based composite negative electrode materials (including silicon carbon, silicon oxygen carbon, silicon and silicon alloys, etc.), with a particle size of 4-30 μm. The conductive additive is a mixed conductive agent of Super-P 5% and carbon nanofiber 2%. The binder is a mixed binder of 10% polyimide (commercially available, 45% solid content) and 2% polyvinylidene fluoride (5% solid content, NMP solvent). All of the above are mass ratios.

[0042]A method for preparing a high specific capacity silicon-based electrode with a variable pore structure is as follows:

[0043] 1) Add the binder to the N-methylpyrrolidone organic solvent, adjust the solid content of the mixture to 30%, and stir manually for 15 minutes; add a conductive agent, and stir manually for 15 minutes; add silicon-based active materials, and stir manually for 15 minutes, After manual st...

Embodiment 2

[0049] In this example, the active material used in the preparation of raw materials is 81% commercial high-capacity silicon-based composite negative electrode materials (including silicon carbon, silicon oxygen carbon, silicon and silicon alloys, etc.), with a particle size of 4-30 μm. The conductive additive is a mixed conductive agent of Super-P 5% and carbon nanotube 2%. The binder is a mixed binder of 10% polyimide and 2% polyvinylidene voltaic. The pore-forming additive is 10% of the total amount of the aforementioned raw materials.

[0050] A method for preparing a high specific capacity silicon-based electrode with a variable pore structure is as follows:

[0051] 1) Add the binder to the N-methylpyrrolidone organic solvent, adjust the solid content of the mixture to 30%, and stir manually for 15 minutes; add a conductive agent, and stir manually for 15 minutes; add silicon-based active materials, and stir manually for 15 minutes, Add ammonium carbonate, a pore-formi...

Embodiment 3

[0058] The raw material is the same as in Example 2, wherein the addition ratio of ammonium carbonate is 10%.

[0059] A method for preparing a high specific capacity silicon-based electrode with a variable pore structure is as follows:

[0060] 1) Add the binder to the N-methylpyrrolidone organic solvent, adjust the solid content of the slurry to 30%, and stir manually for 15 minutes; add the conductive agent, and stir manually for 15 minutes; add silicon-based active materials, stir manually for 15 minutes, and add The pore-forming agent ammonium carbonate with a content of 10% and a D50 of 10 μm was manually stirred for 15 minutes, and then placed in a Flucker high-shear dispersing emulsifier for 40 minutes at a speed of 1800 rpm to obtain a slurry;

[0061] 2) Coat the slurry on the surface of the current collector at a coating speed of 4-5m / min, and vacuumize during coating to obtain a semi-finished negative electrode piece; Treat for 120min; after drying, cut into discs...

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Abstract

The invention provides a silicon-based electrode with an adjustable pore structure; the porosity of the silicon-based electrode is 30%-60%; the pore structure of the silicon-based electrode is adjusted by controlling the compaction density of the electrode and adding a pore-forming additive, wherein the pore-forming additive is one or more of ammonium carbonate, ammonium hydrogen carbonate, ammonium acetate, ammonium nitrate and ammonium chloride. The invention further provides a preparation method of the silicon-based electrode. The porosity of the electrode is controlled by changing the compaction density, and the appropriate porosity can be consistent with the volume expansion rate of a high specific capacity silicon carbon negative electrode material in a lithium intercalation state, so that the integrity of the structure is kept in the circulation process of the electrode; and the volume change of silicon can be effectively buffered through the high-capacity silicon-based negativeelectrode with the variable pore structure, so that the diffusion speed of lithium ions and electrons is increased, the cycling stability of the electrode is obviously improved, and the large-currentdischarge performance of the electrode is improved.

Description

technical field [0001] The invention belongs to the field of secondary batteries, and in particular relates to a silicon-based negative electrode material of a lithium ion battery and a preparation method thereof. Background technique [0002] With the rapid development of electric vehicles, higher demands are placed on the performance of lithium-ion batteries. The key to developing high-performance lithium-ion batteries that meet the above requirements is to develop positive / negative electrode materials with high specific energy and long life. At present, the specific capacity of positive electrode materials has been doubled, so increasing the specific capacity of negative electrode materials is a necessary work for the development of high-performance lithium-ion batteries. At present, the negative electrodes of commercial lithium-ion batteries use graphite-based materials, which are already close to the theoretical capacity, and it is difficult to improve it. [0003] Si...

Claims

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Application Information

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IPC IPC(8): H01M4/134H01M4/1395H01M4/04H01M4/36H01M4/38H01M4/62H01M10/0525
CPCH01M4/0435H01M4/134H01M4/1395H01M4/364H01M4/386H01M4/62H01M4/623H01M10/0525Y02E60/10
Inventor 郑仕琦武兆辉王建涛张向军卢世刚
Owner CHINA AUTOMOTIVE BATTERY RES INST CO LTD
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