Composite porous isolating film and electrochemical device

A technology of separator and porous substrate, which is applied in the field of electrochemistry, can solve the problems of reducing the energy density of electrochemical devices, reducing the thickness of ceramic coatings, and being unable to suppress the expansion of pole pieces, so as to improve low-temperature kinetic performance and cycle performance , Improve energy density, increase low-temperature discharge rate and capacity retention

Active Publication Date: 2014-07-02
DONGGUAN AMPEREX TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, there are also some problems: the adhesion between the ceramic particles and the isolation film is low, which causes the ceramic particles to fall off easily during the processing of the isolation film; the low adhesion between the ceramic particles and the isolation film cannot guarantee safety. Reduce the thickness of the ceramic coating, thereby reducing the energy density of the electrochemical device; the ceramic coating cannot be bonded to the pole piece, and cannot inhibit the expansion of the pole piece during charging and discharging, resulting in deformation of the electrochemical device

Method used

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preparation example Construction

[0032] According to the second aspect of the present invention, the preparation method of the first composite porous isolation membrane includes the steps of: mixing the polymer matrix, plasticizer, antioxidant, and filler A and then extruding through a twin-screw extruder, and performing the first horizontal and then longitudinal Stretch to form a base film, then immerse the stretched base film in an extractant to extract the plasticizer, and then undergo heat setting treatment to obtain a composite porous substrate; mix filler B, binder and solvent evenly Make a slurry, and make the solid content of the slurry reach a specified value, then evenly coat the slurry on at least one surface of the composite porous substrate to obtain a wet film, and dry the wet film in an oven to obtain a composite porous isolation membrane .

[0033] In the preparation method of the first composite porous isolation membrane according to the second aspect of the present invention, the plasticizer...

Embodiment 1

[0058] A lithium-ion secondary battery was prepared according to the method of Comparative Example 1, except that in the preparation of the separator (i.e. in step (3)),

[0059] The polymer matrix polyvinylidene fluoride with a mass percentage of 54%, the plasticizer paraffin oil with a mass percentage of 14.5%, and the antioxidant 2,6-di-tert-butylphenol with a mass percentage of 0.5% and lithium titanium carbonate (Rockwell hardness 3.6) with a mass percentage content of 31% (filler A, surface-modified by the surface modifier aminopropyltriethoxysilane, the surface modifier accounts for 10% of the mass of lithium titanium carbonate 0.1%) are mixed and extruded through a twin-screw extruder, stretched horizontally and then vertically to form a base film, and then the stretched base film is immersed in the extractant dichloroethane to extract the plasticizer paraffin oil After coming out, it is then heat-set to obtain a composite porous substrate with a thickness of 14 μm;

...

Embodiment 2

[0062] A lithium-ion secondary battery was prepared according to the method of Comparative Example 1, except that in the preparation of the separator (i.e. in step (3)),

[0063] The polymer matrix polypropylene with a mass percentage of 20% and calcium sulfate (Rockwell hardness 3.6) with a mass percentage of 80% (modified by surface modifier cinnamic acid, the surface modifier accounted for calcium sulfate The mixture of 0.15% of the mass) and polyimide (mass ratio 1:1, filler A) is melt-extruded through a twin-screw extruder, stretched horizontally and then longitudinally, and then heat-set to obtain a thickness of 20μm composite porous substrate;

[0064] Add the acrylonitrile-styrene-butadiene copolymer (filler B) with a mass percentage of 20% and the binder polyacrylic acid-styrene copolymer with a mass percentage of 80% into the solvent acetone and mix uniformly to prepare Form a slurry and make the solid content of the slurry 55%, and then use screen printing to evenl...

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Abstract

The invention provides a composite porous isolating film and an electrochemical device. The composite porous isolating film comprises a composite porous base material and a composite porous coating which is coated on at least one surface of the composite porous base material. The composite porous base material comprises filler A and a polymer substrate, and the filler A is selected from at least one of inorganic particles and organic particles; the composite porous coating comprises filler B and an adhesive, and the filler B is selected from at least one of inorganic particles and organic particles. The electrochemical device has a composite porous isolating film. By adopting the composite porous isolating film, the heat stability of the composite porous isolating film is improved, the deformation resistance and the capacity maintaining rate of the electrochemical device can be improved, and the cycling performance and low-temperature kinetic performance of the electrochemical device can be improved.

Description

technical field [0001] The invention relates to the field of electrochemical technology, in particular to a composite porous isolation membrane and an electrochemical device. Background technique [0002] Uncoated separators are prone to problems such as shrinkage, fusing, oxidation, and puncture, which pose a great threat to the safety of electrochemical devices. [0003] The separator with traditional ceramic coating can improve the mechanical strength and fusing temperature of the separator, and improve the safety performance of the electrochemical device. However, there are also some problems: the adhesion between the ceramic particles and the isolation film is low, which causes the ceramic particles to fall off easily during the processing of the isolation film; the low adhesion between the ceramic particles and the isolation film cannot guarantee safety. The thickness of the ceramic coating is reduced, thereby reducing the energy density of the electrochemical device;...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M10/0525H01M50/414H01M50/449H01M50/457H01M50/489
CPCY02E60/122H01M50/446H01M50/414H01M50/457H01M50/489H01M10/0525Y02E60/10
Inventor 赵俊华张盛武陈永乐江辉关朝余李晓燕程文强
Owner DONGGUAN AMPEREX TECH
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