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Preparation method of modified diaphragm for polymer lithium-ion battery

A technology of lithium-ion batteries and polymers, which is applied in the direction of secondary battery components, etc., can solve the problems of insufficient adsorption of precursor solutions, high automation requirements, and large investment in drying systems, so as to improve the performance of high-current charging and discharging and Cycling performance, avoiding high equipment automation requirements, and improving market competitiveness

Inactive Publication Date: 2008-08-27
SHENZHEN SENIOR TECH MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, there are still big obstacles in the popularization of this technology. The main problem is that almost the whole process of battery production needs to be carried out in a dry environment, which requires high automation of equipment, large investment in the drying system, and high operating costs, resulting in very high battery manufacturing costs. High, the product price is difficult to compete with liquid batteries in the market
Although the on-site polymerization technology is very suitable for the large-scale production of polymer batteries, and the battery manufacturing cost is low, compared with other technologies, there is a big gap in the technical performance of its products
The main manifestations are: due to the low porosity of the diaphragm used in liquid batteries, the ability to adsorb the precursor solution is not enough, resulting in the insufficient stability and uniformity of the interface between the electrode and the diaphragm after polymerization, resulting in high internal resistance and low high-current discharge platform of the polymer battery

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] The cross-linking agent butanediol diacrylate and polyvinylidene fluoride are mixed according to the mass ratio of 40%:70%, and then dissolved in acetone solvent. By adjusting the amount of solvent, the viscosity of the modified liquid is controlled at about 70Psi. Then a polyethylene microporous membrane with a thickness of 16 micrometers was immersed in the above-mentioned modifying solution. After drying, a modified separator with a thickness of 20 microns was obtained.

Embodiment 2

[0033] After mixing the crosslinking agent pentanediol diacrylate and polyvinylidene fluoride-hexafluoropropylene copolymer according to the mass ratio of 14:80, they are dissolved in tetrahydrofuran solvent. By adjusting the amount of solvent, the viscosity of the modified liquid is controlled at about 100Psi. Then the polyethylene-polypropylene composite microporous membrane with a thickness of 25 microns was immersed in the above-mentioned modifying solution. After drying, a modified separator with a thickness of 35 microns was obtained.

Embodiment 3

[0035] Dissolve polyvinylidene fluoride-hexafluoroethylene in acetone solvent, adjust the amount of solvent to control the viscosity of the modified solution at about 40Psi, and then impregnate a polyethylene-polypropylene microporous membrane with a thickness of 20 microns in the above modified solution, and dried to obtain a modified diaphragm with a thickness of 25 microns.

[0036] When using separator of the present invention to prepare lithium-ion battery, the method of following formula can be used to form positive pole piece and negative pole piece:

[0037] In the positive electrode slurry and the negative electrode slurry used in the preparation of liquid lithium ion batteries, add high-boiling chemical crosslinking agent monomers respectively, and the mass percentage of the added chemical crosslinking agent monomers in the solid content of the pole piece coating is 0.01 %-1%, and then prepare the corresponding positive pole piece and negative pole piece according to...

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Abstract

The invention relates to the field of modified diaphragm preparation process technology for lithium ion cells. The preparation process of modified diaphragm for polymer lithium ion cell in the invention comprises the following steps: forming modified diaphragm, mixing chemical cross-linking agent monomer with polymer which has physical cross-linking property according to molar ratio of 10:100-50:50, dissolving the mixture into organic solvent to form modifying fluid whose viscosity is kept within 30Psi-300Psi, using conventional liquid lithium ion cell diaphragm as diaphragm substrate to dip in the modifying fluid, drying after taking out, thereby obtaining the modified diaphragm. Since porous polymer layer on the surface of the modified diaphragm has strong fluid storage ability for electrolyte, stable and even interface and smooth ion transmission channel can be obtained after the modified diaphragm is used between electrode which is solidified in cross-linking and diaphragm, thereby effectively increasing the large current charge and discharge property and cycling property of polymer cell products.

Description

technical field [0001] The invention relates to the technical field of a method for preparing a modified diaphragm for a lithium ion battery. Background technique [0002] Polymer lithium ion battery is a new generation of high specific energy secondary battery system developed on the basis of liquid lithium ion battery. Compared with traditional liquid lithium-ion batteries, it has the following obvious advantages: [0003] (1) The use of polymer electrolyte instead of liquid electrolyte solution can effectively avoid the electrolyte leakage problem that may exist in liquid batteries, and the reliability of the battery is higher; [0004] (2) Using lightweight soft plastic material as the shell, compared with liquid batteries using metal shells, on the one hand, it can effectively reduce the quality of the battery shell, improve the quality efficiency of the battery, and make the polymer lithium-ion battery more efficient. High specific energy, such as the specific energy...

Claims

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Application Information

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IPC IPC(8): C08J5/22C08J7/12C08L27/16C08L27/18H01M10/02
CPCY02E60/10
Inventor 杨梅
Owner SHENZHEN SENIOR TECH MATERIAL
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