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High-performance binder for silicon materials for lithium ion batteries and preparation method thereof

A lithium-ion battery and binder technology, which is applied in the direction of battery electrodes, circuits, electrical components, etc., to achieve the effects of easy cyclization, alleviating volume expansion, and improving microscopic composition

Active Publication Date: 2015-04-22
JIANGXI XIAN CAI NANOFIBERS TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, silicon particles are used as the electrode active material, and the traditional binder PVDF (polyvinylidene fluoride) cannot solve many problems such as the separation of silicon particles from the electrode due to volume expansion during the cycle.

Method used

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  • High-performance binder for silicon materials for lithium ion batteries and preparation method thereof
  • High-performance binder for silicon materials for lithium ion batteries and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Prepare a kind of binder for lithium ion battery silicon material of the present invention, preparation method is as follows:

[0038] With a mechanical stirrer, N 2Add monobutyl itaconate (accounting for 5% of monomer mass), azoisobutyronitrile (accounting for 0.5% of monomer mass), n-butyl acrylate in different proportions to the 250mL four-necked flask with protective device and thermometer (accounting for 2% of the mass of acrylonitrile monomer), emulsifier OP10 (accounting for 0.5% of the mass of the monomer), acrylonitrile monomer and water (9 times the mass of the monomer), heated to 110 ° C, and took it out after 24 hours of reaction , after washing and filtering with deionized water several times, the polymer powder whose main component is polyacrylonitrile is obtained, which is used as the binder I for silicon materials of lithium-ion batteries, and its molecular weight is about 280,000.

Embodiment 2

[0040] Prepare a kind of binder for lithium ion battery silicon material of the present invention, preparation method is as follows:

[0041] With a mechanical stirrer, N 2 Add monobutyl itaconate (accounting for 8% of the monomer mass), azoisobutyronitrile (accounting for 0.5% of the monomer mass), n-butyl acrylate in different proportions in the 250mL four-necked flask with protective device and thermometer (2% of monomer mass), emulsifier OP10 (0.5% of monomer mass), acrylonitrile monomer (90% of monomer mass) and water (9 times of monomer mass), heated to Take it out after reacting for 24 hours at 85°C, wash and filter for many times to obtain a polymer powder whose main component is polyacrylonitrile, which is used as the binder II for silicon material of lithium ion battery, and its molecular weight is about 354,000.

Embodiment 3

[0043] In this embodiment, a high-purity crystalline silicon (Wt%=99.9%) material with a diameter of ~100nm and a particle size of ~1 μm Super P, 3 μm mesophase carbon microspheres, and MWCNTs are selected as the conductive agent (Super P: MCMB: MWCNTs w / w=60:35:5), using the binder I prepared in Example 1 as the binder material for preparing electrodes.

[0044] Follow the steps below to prepare high-purity crystalline silicon electrodes:

[0045] 1) Weighing 50% of the silicon-based active material and 20% of the carbon material conductive agent according to mass percentage and mixing and dispersing evenly;

[0046] 2) By mass percentage, take 30% of the binder I prepared in Example 1 as binder powder, dissolve it in an appropriate amount of NMP, disperse evenly, and stir into a transparent sol;

[0047] 3) Add the powder obtained in step 1) to the sol-like material obtained in step 2), control the solid content at 40%, stir vigorously, and form a slurry after stirring eve...

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Abstract

The invention provides a high-performance binder for silicon materials for lithium ion batteries, which is a polyacrylonitrile copolymer, a polymeric monomer of the copolymer comprises acrylonitrile, also comprises a second monomer and / or a third monomer; and the second monomer is a monobutyl itaconate monomer, and the third monomer is selected from a mixture of one or more of an itaconic acid, sodium allylsulfonate, acrylamide, amino, a pyridyl or acylamino monomer, n-butyl acrylate or methyl acrylate. The invention also provides a preparation method of the binder. Compared with existing binders, the binder disclosed by the invention has better binding power, can effectively improve the expansion of silicon materials in the processes of charging and discharging, and can improve the performance of a silicon electrode in the process of cycling. Meanwhile, the binder is simple in preparation method, low in cost and good in repeatability, and can achieve the practical need of mass production.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a silicon negative electrode binder for lithium ion batteries and a preparation method thereof. Background technique [0002] At this stage, the anode material of lithium-ion batteries is still dominated by graphite materials, and its capacity utilization has basically reached the theoretical value (372mA·h / g). In order to meet the requirements of next-generation wireless communication equipment and hybrid electric vehicles, we need to significantly increase the energy density and power density of lithium-ion batteries. The silicon negative electrode has a specific capacity ten times higher than that of the traditional carbon negative electrode (mass specific capacity: 4200mA·h / g; volume specific capacity: 9786mA·h / cm 3 ), and has a relatively low discharge potential (the average delithiation potential is about 0.4V), and the silicon element is abundant...

Claims

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Application Information

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IPC IPC(8): H01M4/62H01M4/1395C08F220/44C08F220/18C08F222/16C08F2/30
CPCC08F2/30C08F220/44H01M4/1395H01M4/622C08F220/1804C08F222/16Y02E60/10
Inventor 侯豪情王琦赵丹
Owner JIANGXI XIAN CAI NANOFIBERS TECH
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