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Polyimide porous membrane and preparation method and lithium ion battery thereof

A polyimide and porous membrane technology, applied in battery pack parts, circuits, electrical components, etc., can solve the problem of uneven pore size of polyimide membrane, and achieve high processing yield and uniform pore diameter distribution. , the effect of high thermal stability

Active Publication Date: 2012-09-12
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The object of the present invention is to overcome the disadvantages of the uneven pore size of the polyimide membrane in the above-mentioned prior art, and provide a polyimide membrane with uniform pore size Amine porous membrane and preparation method thereof, also provides a lithium ion battery using the porous membrane as a battery separator

Method used

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  • Polyimide porous membrane and preparation method and lithium ion battery thereof
  • Polyimide porous membrane and preparation method and lithium ion battery thereof
  • Polyimide porous membrane and preparation method and lithium ion battery thereof

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preparation example Construction

[0015] The preparation method of the polyimide porous membrane provided by the invention comprises forming a polyamic acid membrane from a mixture containing polyamic acid, a pore-forming substance and a solvent, contacting the polyamic acid membrane with a coagulation solution, and performing imidization, The solvent is a solvent that dissolves polyamic acid but slightly dissolves or does not dissolve pore-forming substances, and the coagulation liquid is a liquid that dissolves pore-forming substances but slightly dissolves or does not dissolve polyamic acid. "Slightly soluble" as described herein means that the solubility at 25°C is less than 1% (w / w) and greater than 0.01% (w / w); "insoluble" means that the solubility at 25°C is less than 0.01% (w / w).

[0016] According to the preparation method provided by the present invention, preferably, the weight ratio of the pore-forming substance to the polyamic acid is 0.01-0.3:1, and the weight ratio of the polyamic acid to the sol...

Embodiment approach

[0047] According to a preferred embodiment of the present invention, the preparation method of polyimide porous membrane provided by the present invention comprises the steps:

[0048] (1) Tetraacid dianhydride and organic diamine are added to the solvent according to the molar ratio of 0.8-1.2:1, the amount of solvent used is such that the concentration of the obtained polyamic acid is 5-40% by weight, at 20-70°C After stirring and reacting for 3-15 hours, add pore-forming substances, the weight ratio of pore-forming substances to the obtained polyamic acid is 0.01-0.3:1; vacuum degassing at the same temperature for 1-12 hours to obtain a polyamic acid solution;

[0049] (2) At a temperature of 10-40°C and a relative humidity of 20-80%, the above polyamic acid solution is coated on a stainless steel or glass support, dried at 20-200°C, and the solvent is removed to obtain 5 - 50 micron polyamic acid film;

[0050] (3) immersing the support body of the above-mentioned polyami...

Embodiment 1

[0064] (1) 4,4'-diaminodiphenyl ether and pyromellitic dianhydride are added to 300 milliliters of N,N-dimethylacetamide at a molar ratio of 1:1, wherein the solid content is 10% by weight . Stir the reaction at 25°C for 8 hours, then add 3 grams of propylene glycol methyl ether acetate, and vacuum degassing at this temperature for 1 hour to obtain a viscous mixture with an intrinsic viscosity η int =150 ml / g (measurement conditions: Ubbelohde viscometer, constant temperature 30°C, the mixture is diluted to a solid content of 0.005 g / ml);

[0065] (2) At a temperature of 10°C and a relative humidity of 50%, the above mixture is coated on a stainless steel plate, dried at 100°C for 20 minutes, and then the solvent is removed to obtain a polyamic acid film;

[0066] (3) Dip the above-mentioned stainless steel plate with polyamic acid film in 100 ml of coagulation solution composed of ethanol, ether and acetone (the volume ratio of ethanol, ether and acetone is 3:2:1) at 20°C fo...

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Abstract

The invention provides a polyimide porous membrane and the pore distribution of the polyimide porous membrane is as follows: the pore volume of 50-300nm of pores is above 75% of the total pore volume and the pore volume of less than 50nm and more than 300nm of pores is below 25%. The invention also provides a preparation method of the polyimide porous membrane and a lithium ion battery using the porous membrane as diaphragm. The polyimide porous membrane provided by the invention has uniform pore distribution and higher mechanical strength so that the lithium ion battery prepared by using theporous membrane as diaphragm has higher service life, processing yield and thermal stability and the safety performance of the cell is greatly improved.

Description

technical field [0001] The invention relates to a polyimide porous membrane, a preparation method of the polyimide porous membrane, and a lithium ion battery using the porous membrane as a battery diaphragm. Background technique [0002] So far, lithium ion secondary batteries using liquid electrolytes have been widely used. However, since the liquid electrolyte needs to be packaged in a sealed metal shell, in some cases of improper use, such as when the battery is working in a high temperature environment, the external heat is transferred to the inside of the battery through the metal shell, or when the discharge current is large. Overheating inside or outside the battery will greatly increase the internal pressure of the battery, and the battery will explode due to the thermal instability of the liquid electrolyte. Therefore, there are potential safety hazards in lithium-ion secondary batteries using liquid electrolytes, which limits the use of liquid electrolytes for lith...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08J9/26C08L79/08H01M2/14H01M2/16H01M50/403H01M50/423H01M50/489
CPCY02E60/12Y02E60/10
Inventor 杨卫国江林宫清
Owner BYD CO LTD
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