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Lithium ion battery diaphragm with hydrophilic cross-linking surface layer and manufacture method of lithium ion battery diaphragm

A lithium-ion battery, cross-linked layer technology, applied in battery pack parts, circuits, electrical components, etc., can solve the problem of affecting battery cycle performance and charge-discharge efficiency, increase lithium-ion battery internal resistance, low porosity and air permeability and other problems, to achieve the effect of easy implementation, improved liquid absorption rate and liquid retention rate, high porosity and air permeability

Active Publication Date: 2012-11-14
扬州市永佳车辆配件有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The technical problem to be solved by the present invention is: due to surface modification of polyolefin microporous membranes in the prior art, it is easy to change the pore structure of the microporous membranes, resulting in uneven pore size distribution, low porosity and air permeability, and increased lithium ion density. The internal resistance of the battery affects the cycle performance and charge and discharge efficiency of the battery

Method used

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  • Lithium ion battery diaphragm with hydrophilic cross-linking surface layer and manufacture method of lithium ion battery diaphragm
  • Lithium ion battery diaphragm with hydrophilic cross-linking surface layer and manufacture method of lithium ion battery diaphragm
  • Lithium ion battery diaphragm with hydrophilic cross-linking surface layer and manufacture method of lithium ion battery diaphragm

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0046] Add polyvinyl alcohol (polymerization degree 600, alcoholysis degree 78%) and distilled water into a three-necked flask at a ratio of 25:75 (wt%), heat up to 60°C in a water bath while stirring, stir and dissolve for 1 hour, and obtain polyvinyl alcohol Aqueous solution of vinyl alcohol. Soak the polypropylene microporous membrane in the solution for 30 minutes, and then take it out. Wash the polypropylene microporous membrane with dimethyl sulfoxide, and then dry the microporous membrane with hot air at 80° C. for 10 minutes to obtain a polypropylene microporous membrane whose pores are filled and protected by polyvinyl alcohol.

[0047] Submerge the polypropylene microporous membrane filled and protected by polyvinyl alcohol into an ethanol solution containing 1% benzoin dimethyl ether and 20% N-hydroxyethylacrylamide, blow in nitrogen to remove the air, and irradiate with ultraviolet light for 10 minutes. After the membrane is taken out, the surface of the membrane ...

Embodiment 2

[0051] The chemical grafting of the polypropylene microporous membrane in Example 1 was changed from UV-induced grafting to initiator-induced grafting. The steps for the initiator to initiate grafting are: immerse the polypropylene microporous membrane filled and protected by polyvinyl alcohol into an ethanol solution containing 0.3% potassium persulfate and 5% N-hydroxyethylacrylamide, and react at 70°C After 3 hours, the membrane surface was washed with acetone after the membrane was taken out to obtain a polypropylene microporous membrane grafted with N-hydroxyethylacrylamide on the surface.

[0052] All other steps were the same as in Example 1 to obtain a polypropylene microporous membrane with a hydrophilic cross-linked layer on the surface. The performance data of the modified microporous membrane are listed in Table 1.

Embodiment 3

[0054] Polyvinyl alcohol (polymerization degree 2000, alcoholysis degree 78%) and distilled water were prepared into a polyvinyl alcohol aqueous solution at a ratio of 25:75 (wt%), and the rest were the same as in Example 1. The performance data of the modified microporous membrane As described in Table 1.

[0055] Due to the high degree of polymerization of polyvinyl alcohol and the high viscosity of its aqueous solution, it is difficult for the polymer solution to fill the pores of the microporous membrane. Therefore, the protection of polyvinyl alcohol on the pores of the microporous membrane is insufficient, resulting in a large decrease in the porosity and air permeability of the modified PP microporous membrane.

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Abstract

The invention relates to a lithium ion battery diaphragm with a hydrophilic cross-linking surface layer and the manufacture method of the lithium ion battery diaphragm. The battery diaphragm is a polyolefin microporous film; and the manufacture method comprises: (1) surface pretreatment of the polyolefin microporous film, (2) surface grafting reaction of the polyolefin microporous film, (3) cross-linking of a surface hydrophilic layer of the polyolefin microporous film; and (4) post-treatment of the polyolefin microporous film. The prepared microporous film can still keep the original porosity and penetration rate, and is improved obviously in the surface hydrophilicity so as to facilitate the full wetting of electrolyte on the surface of the diaphragm, thereby lowering the internal resistance of the lithium ion battery and realizing the excellent cycling performance and higher charging-discharging efficiency of the battery. Meanwhile, the heat-resistant contraction performance and the size stability of the diaphragm under heating are improved, thereby improving the use safety of the lithium ion battery.

Description

technical field [0001] The invention relates to a lithium-ion battery separator and a preparation method thereof, in particular to a polyolefin microporous membrane with a hydrophilic crosslinked surface layer on the surface and a preparation method thereof. Background technique [0002] Lithium-ion battery is a new type of chemical power system. Compared with traditional nickel-cadmium or nickel-hydrogen batteries, it has the advantages of high energy, long cycle life, no memory effect, fast charge and discharge, etc. It can be used in mobile phones, notebook computers, cameras, etc. The power supply required for portable electronic products such as video recorders and environmentally friendly electric vehicles. The battery separator is an important part of the lithium-ion battery. Its main functions are: (1) to isolate the positive and negative electrodes of the battery, so that the electrons inside the battery cannot freely pass through and prevent short circuits; (2) to ...

Claims

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Application Information

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IPC IPC(8): H01M2/16C08J9/36C08J9/42C08J7/18
CPCY02E60/12Y02E60/10
Inventor 蒋姗徐丹姚自力杨茜朱梦冰俞强邱圆鑫丁永红朱威张洪文
Owner 扬州市永佳车辆配件有限公司
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