High-temperature-resistant composite diaphragm for lithium ion battery and preparation method thereof

A technology for lithium-ion batteries and composite diaphragms, applied in secondary batteries, battery pack components, circuits, etc., can solve the problem of not being able to fully utilize the high-temperature resistant nanofiber porous membrane, increase the thermal dimensional stability of the diaphragm, and the self-discharge rate of the battery Advanced problems, to achieve the effect of simple and easy preparation process, improved mechanical properties, and improved safety

Pending Publication Date: 2020-11-10
BEIJING YUCHENG TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the electrospun nanofiber membrane itself has high porosity and large pore size, and its application alone will lead to a high self-discharge rate of the battery. Applying the electrospinning method to spray the nanofiber membrane on the surface of the polyolefin separator for modification will improve the wettability of the separator. Liquid absorption, increasing the thermal dimensional stability of the separator
For example, the patent CN107275554A of Dalian University of Technology is based on electrospinning technology to prepare polyaryl ether sulfone ketone / polyolefin three-layer composite membrane. The nanofiber membrane / polyolefin multilayer composite membrane is prepared by electrospinning on the surface. The bonding force between the two is weak, which is not enough to fully utilize the respective advantages of the high temperature resistant nanofiber porous membrane and the polyolefin separator, and the yield of the process is lower

Method used

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  • High-temperature-resistant composite diaphragm for lithium ion battery and preparation method thereof
  • High-temperature-resistant composite diaphragm for lithium ion battery and preparation method thereof
  • High-temperature-resistant composite diaphragm for lithium ion battery and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0034] A: Preparation of polymer porous membrane by electrospinning method:

[0035] 10g of PAN with a molecular weight of 150,000 was added to 90g of N-methylpyrrolidone (NMP), stirred at 25°C until the PAN was completely dissolved, the solution became transparent, and an electrospinning solution with a mass fraction of 10% was obtained. The spinning solution was injected into the electrospinning machine to carry out electrospinning under the conditions of 15KV voltage and a distance of 5 cm between the spinning head and the receiving substrate to obtain a polymer nanofiber porous membrane. After rolling, the porosity was adjusted to 35%, and the thickness was 10 μm. High temperature resistant polymer porous membrane (A 1 1), high temperature resistant polymer porous membrane (A 2 1);

[0036] B: The two surfaces of the polyethylene diaphragm B1 with a thickness of 12 μm are modified, and the surface is coated with a PVDF adhesive solution with a concentration of 4%, and th...

Embodiment 2

[0039] A: Preparation of polymer porous membrane by electrospinning method:

[0040] The polyimide precursor is synthesized by solution condensation polymerization in DMF solvent with diamine and dibasic acid anhydride monomers at a molar ratio of 1:1

[0041] ——Polyamic acid solution, to obtain a polyamic acid electrospinning solution with a solid content of 25%, inject the prepared electrospinning solution into an electrospinning machine and perform electrospinning under the conditions of 50KV voltage and a distance of 20cm from the spinning head to the receiving substrate , to make a polyamic acid nanofiber membrane; place the prepared polyamic acid nanofiber membrane in a hot furnace, raise the temperature to 450°C, and keep it for 0.1h to obtain a polyimide (PI) nanofiber porous membrane with a thickness of 2 microns, porosity 60%; as a high temperature resistant polymer porous membrane (A 1 2), high temperature resistant polymer porous membrane (A 2 2);

[0042] B: Th...

Embodiment 3

[0045] A: Preparation of polymer porous membrane by electrospinning method:

[0046] Add 8g of P84 with a molecular weight of 300,000 to 92g of N-methylpyrrolidone (NMP), stir at 70°C until completely dissolved, the solution becomes transparent, and an electrospinning solution with a mass fraction of 8% is obtained. The prepared electrospinning The silk liquid is injected into the electrospinning machine to carry out electrospinning under the condition of 36KV voltage and 15cm distance between the spinning head and the receiving substrate to obtain a polymer nanofiber porous membrane with a thickness of 10 μm and a porosity of 85% as a high temperature resistant polymer porous membrane ( A 1 3), high temperature resistant polymer porous membrane (A 2 3);

[0047] B: Modify the polyethylene separator B3 with a thickness of 25 μm, and apply 2kw plasma to irradiate the polyolefin separator for 5 minutes to make the surface have polar groups, so as to have better interfacial adh...

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Abstract

The invention relates to a high-temperature-resistant multi-layer composite diaphragm for a lithium ion battery and a preparation method thereof. The diaphragm is of an A1/B/A2 three-layer structure or an A1/B two-layer structure, wherein A1 and A2 are high-temperature-resistant polymer porous membranes prepared by applying an electrostatic spinning process; the middle layer B is a polyolefin diaphragm, A1/B/A2 or A1/B is compounded through a compounding process, and a three-layer or two-layer composite diaphragm is obtained. The lithium battery diaphragm prepared by the invention has the characteristics of lower closed pore temperature of the middle layer and high temperature resistance of the porous diaphragm on the surface layer, the preparation process is simple and feasible, the adhesive force between different diaphragms is strong, the thermal dimensional stability is excellent, and the dimensional stability, the integrity and the electrolyte wettability of the diaphragm under the condition of extremely high temperature of the lithium ion battery can be improved; therefore, the safety of the battery is improved and the application prospect is good.

Description

technical field [0001] The invention belongs to the technical field of novel lithium-ion battery separators, and in particular relates to a high-temperature-resistant porous composite membrane for lithium-ion batteries and a preparation method thereof. Background technique [0002] With the increasing demand for global energy, lithium-ion batteries are widely used as an energy storage device that can store chemical energy conveniently and quickly and convert the stored energy into electrical energy efficiently and without pollution. Lithium-ion batteries are composed of positive and negative electrodes, electrolyte, and separator. The separator plays an important role in allowing only lithium ions to pass through and avoiding direct contact between the positive and negative electrodes to cause short circuit and battery explosion. Most of the lithium-ion batteries currently used in the market are polyethylene (PE), polypropylene (PP) and their PP-PE composite films, which are...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M10/0525
CPCH01M10/0525Y02E60/10
Inventor 王杰
Owner BEIJING YUCHENG TECH CO LTD
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