Preparation method of diaphragm with high porosity and safety performance

A technology with high porosity and safety performance, applied in the field of lithium-ion batteries, can solve the problems of low tensile strength and puncture strength, poor air permeability, and low porosity of the diaphragm, so as to improve the tensile strength and puncture strength, avoid The effect of clogging

Inactive Publication Date: 2020-08-11
华鼎国联四川动力电池有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Aiming at the problems of low porosity, poor air permeability and overall mechanical properties of the diaphragm in the prior art, including low tensile strength and puncture strength, the p...

Method used

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Examples

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Effect test

preparation example Construction

[0033]The preparation method of the diaphragm with high porosity and safety performance of the present invention, the specific implementation steps are as follows:

[0034] (1) Pre-immerse the porous substrate in the solvent medium to saturate the micropores with the adsorption solvent; the porous substrate is PP, PE or a multilayer composite material; the thickness of the substrate is 5-20 μm. The solvent medium is solvents such as acetone, ethanol, ether, or other polar solvents.

[0035] (2) coating a layer of ceramic coating (and / or gluing) slurry on the base material full of prepreg medium; the ceramic slurry includes solvent, inorganic ceramic particles, binding agent, pore-forming agent, Cross-linking agent and thickening agent, etc.; the gluing slurry includes solvent, binder, pore-forming agent, cross-linking agent and thickening agent, etc.

[0036] Wherein, the solvent is an aqueous solvent such as water, alcohols, ethers, or an oily solvent such as N-methylpyrroli...

Embodiment 1

[0047] (1) Select a PE separator with a thickness of 12 μm as the base material, and immerse it in acetone for a pre-soaking time of 4 minutes to obtain the infiltrated base material. The physical properties of the substrate PE separator: membrane rupture temperature 152°C, porosity 49.5%, air permeability 408s / 100cc, tensile strength 125MPa, puncture strength 3.5N, elongation at break 62%, heat shrinkage 2.9%.

[0048] (2) Coating a layer of ceramic coating slurry on the substrate filled with acetone solvent by spraying. According to weight percentage, NMP solvent in the slurry accounts for 87.6% of the whole slurry, alumina accounts for 10%, polyvinylidene fluoride accounts for 2%, petroleum ether 0.3%, and BPO 0.1%.

[0049] (3) Heat the ceramic-coated diaphragm to 75° C. for 10 minutes, the cross-linking agent is cross-linked, and the binder molecules are cross-linked together.

[0050] (4) Reheat the diaphragm to 90° C. for 2 minutes, and dry to obtain a ceramic diaphrag...

Embodiment 2

[0054] (1) Select a PE separator with a thickness of 12 μm as the substrate, and immerse it in ethanol for a pre-soaking time of 3 minutes to obtain an infiltrated substrate.

[0055] (2) Coating a layer of ceramic coating slurry on the substrate filled with ethanol solvent by spraying. According to weight percentage, NMP solvent in the slurry accounts for 76.3% of the whole slurry, silicon oxide accounts for 20%, polyvinylidene fluoride accounts for 3%, petroleum ether 0.5%, and GA 0.2%.

[0056] (3) Heat the ceramic-coated diaphragm to 70° C. for 12 minutes, the cross-linking agent is cross-linked, and the binder molecules are cross-linked together.

[0057] (4) Reheat the diaphragm to 100° C., hold the temperature for 1 min, and dry to obtain a ceramic diaphragm with high porosity and high mechanical properties.

[0058] (5) The obtained base material is coated with a ceramic coating with a single side of 2 μm.

[0059] (6) The rupture temperature of the gained ceramic co...

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Abstract

The invention relates to a preparation method of a diaphragm with high porosity and safety performance, and belongs to the technical field of lithium ion batteries. The method comprises: pre-immersinga porous base material in a solvent medium, so that the micropores of the base material are filled with the solvent medium; coating the base material filled with the pre-immersing medium with a layerof ceramic slurry and/or glue slurry; heating the diaphragm coated with the ceramic or the glue, wherein a cross-linking agent acts, so that the molecules of the binder are cross-linked together; andheating to a high temperature, and drying to obtain the ceramic and/or glued diaphragm with high porosity and high mechanical properties. According to the invention, a base material pre-impregnationmedium is adopted, so that pores of the base material can be prevented from being blocked by surface coating slurry, and the porosity of the original base material is ensured; binder molecules are cross-linked together by utilizing a cross-linking agent, so that the overall tensile strength and puncture strength of the diaphragm are improved; and the porosity of the surface coating is ensured by utilizing a pore-forming agent, so that the coated diaphragm with high porosity and high safety performance can be finally obtained.

Description

technical field [0001] The invention relates to a method for preparing a diaphragm with high porosity and safety performance, in particular to a diaphragm coating slurry and a preparation method thereof, belonging to the technical field of lithium ion batteries. Background technique [0002] The main function of the lithium battery separator is to separate the positive and negative plates in the battery, to prevent the direct contact of the positive and negative plates to cause short circuit, and it has electronic insulation and ion conductivity. The separator has a large number of zigzagging micropores through which the ionophores in the electrolyte can freely pass through the micropores and migrate between the positive and negative plates to form the internal conductive loop of the battery, while the electrons migrate between the positive and negative electrodes through the external loop A current is formed for use by electrical equipment. With the development of science ...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M10/0525
CPCH01M10/0525H01M50/403Y02E60/10
Inventor 李娟马艳孟金孙延先
Owner 华鼎国联四川动力电池有限公司
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