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Composite porous membrane and preparation method thereof

A porous film and adhesive technology, applied in electrical components, circuits, battery pack components, etc., can solve the problems of reducing the porosity of composite separators, affecting lithium ion transport performance, etc., achieving low thermal shrinkage, good cycle characteristics, The effect of excellent temperature resistance

Active Publication Date: 2012-05-02
BEIJING NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The porosity of the polyolefin diaphragm is usually 30-70%, and the size of the micropores is less than 200nm. In the above-mentioned disclosed method, the pores of the composite diaphragm formed due to the penetration of the coating solution into the micropores during the coating process will be blocked. The rate is reduced, which affects the transport performance of lithium ions in the microporous channel

Method used

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  • Composite porous membrane and preparation method thereof
  • Composite porous membrane and preparation method thereof
  • Composite porous membrane and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0063] Vinylidene fluoride-hexafluoropropylene copolymer (Kynar2801) (20 parts by weight) was added to a mixed solvent (600 parts by weight) of N-methyl 2-pyrrolidone (NMP) and acetone (wherein NMP: acetone v / v = 7:3), the solution was obtained after fully dissolving under stirring conditions, and slowly added aluminum oxide (85 parts by weight, average particle size 0.5 μm) and gelatin (5 parts by weight) to the solution, under ultrasonic and strong shear Continue to stir under the conditions to form a stable suspension, which is the coating slurry. A polyethylene single-layer separator with a thickness of 25 μm (porosity 35%) prepared by a wet method is first immersed in NMP to fill the inside of the separator with NMP, and after removing excess NMP on the surface, scrape a layer of coating on one surface of the separator. Apply the slurry, and after drying, form an aluminum oxide coating with a thickness of 5 μm to obtain a composite diaphragm with a thickness of 30 μm coat...

Embodiment 2

[0065] Polyurethane (10 parts by weight) is added in ethyl acetate (500 parts by weight), fully dissolved under stirring to obtain a solution, and zirconium dioxide (50 parts by weight, average particle diameter 1.0 μm), polyethylene wax (40 parts by weight, average particle size 0.5 μm) and polyoxyethylene ether (3 parts by weight), continue to stir under ultrasonic and strong shear conditions to form a stable suspension that is the coating slurry. The polypropylene single-layer diaphragm (porosity 45%) with dry uniaxial stretching thickness of 25 μm is first immersed in acetone so that the interior of the diaphragm is filled with acetone, and after the solvent on the surface of the diaphragm is volatilized, transfer printing One layer of coating slurry is coated, and after drying, a composite coating with a thickness of 7 μm is formed to obtain a composite diaphragm with a thickness of 32 μm coated on one side (the cross-sectional schematic diagram is as follows: figure 1 e ...

Embodiment 3

[0067] Add silicon dioxide (70 parts by weight, average particle diameter 2 μm), sodium polyacrylate (3 parts by weight) and gelatin (7 parts by weight) to polyurethane aqueous dispersion (20 parts by weight (solid content 30%)), add appropriate amount After adding water, stir under ultrasonic and strong shear conditions to form a stable suspension, which is the coating slurry. The double-sided dip-coating of the surface of a 40 μm thick polypropylene single-layer separator (porosity 42%) with a dry biaxially stretched thickness is formed after drying to a silicon dioxide coating with a thickness of 5 μm, and the thickness of the double-sided coating is 50μm composite diaphragm (the schematic diagram of its cross-section is shown in figure 1 shown in b). The air permeability and thermal shrinkage performance at 140° C. of the tested composite film are listed in Table 1 below.

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Abstract

The invention provides a composite porous membrane, which comprises a porous membrane substrate, inorganic particles and / or thermo-sensitive particles, and a binding agent, wherein the inorganic particles and / or the thermo-sensitive particles are bound on one side or two sides of the porous membrane substrate through the binding agent, and thereby an independent inorganic particle coating and / or an independent thermo-sensitive particle coating and / or a mixed coating with the inorganic particles and the thermo-sensitive particles are formed; and pores at the inner part of the porous membrane substrate are not provided with the binding agent and / or the inorganic particles and / or the thermo-sensitive particles. The composite porous membrane provided by the invention has higher porosity while having good high-temperature-resistant performance, and is suitable for preparing power lithium-ion batteries with high discharge rates.

Description

technical field [0001] The invention relates to a porous membrane and a manufacturing method thereof, in particular to an organic-inorganic composite porous membrane and a manufacturing method thereof. Background technique [0002] Lithium-ion batteries have penetrated into all aspects of life. In addition to being widely used in digital electronic products such as mobile phones, notebook computers, and MP3s, they have also been used in some high-power power batteries such as electric vehicles, electric bicycles, and electric tools in recent years. . Power lithium-ion batteries have higher power / energy density than communication lithium-ion batteries, which put forward higher requirements for the safety performance of power lithium-ion batteries. The separator plays the role of blocking the positive and negative electrodes and providing lithium ion transmission channels in the lithium-ion battery, and the high-temperature thermal stability of the separator will directly aff...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M2/18
CPCY02E60/12Y02E60/10
Inventor 周建军李林张灏
Owner BEIJING NORMAL UNIVERSITY
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