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Coating composition for separator of lithium ion secondary battery and method for producing the separator

A coating composition and secondary battery technology, applied in secondary batteries, battery components, coatings, etc., can solve the problems of diaphragm rupture, low closed cell temperature, and low melt fracture temperature

Active Publication Date: 2014-10-29
河南惠强新能源材料科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the disadvantage is that its melt rupture temperature (Melt-downtemperature) is also low. As the temperature of the battery rises and exceeds the melting point by about 15°C, the diaphragm will rupture when heated, causing the internal structure of the battery to collapse and cause an explosion. Therefore, usually we A material with a low current interruption temperature and a high melt fracture temperature is desired
However, although the PET base film has good heat resistance and its melting point is 256-265°C, based on the safety considerations of lithium-ion secondary batteries, the low closed-cell temperature that should be provided as a lithium-ion secondary battery separator is ignored. It is difficult to think that such a diaphragm has a reliable safety performance

Method used

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  • Coating composition for separator of lithium ion secondary battery and method for producing the separator

Examples

Experimental program
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Embodiment 1

[0047]The copolymer emulsion of lipophilic monomer n-butyl acrylate, hydrophilic monomer sodium acrylate and functional group monomer acrylic acid is selected as (the composition of the copolymer is, n-butyl acrylate: sodium acrylate: acrylic acid=6:3:1, weight ratio ) is a heat-resistant resin binder, which is dissolved and dispersed for 1 hour at room temperature with water as a solvent. Then add 80 parts of glass powder (average particle size of 0.8 μm) and 20 parts of the above heat-resistant resin binder solution into 100 parts of deionized water, and then disperse and mix it through a sand mill for 3 hours to obtain Coating solution.

[0048] Coat the coating solution prepared above with a wire bar on both surfaces of a 20 μm ultra-high molecular weight polyethylene-based film (abbreviated as UHMWPE, the same below), and then dry it in a blast drying oven at a temperature of 50 ℃. Composite microporous membranes with a total thickness of 6 μm (3 μm respectively) on bot...

Embodiment 2

[0051] The difference between this example and Example 1 is that: the coating solution prepared in Example 1 is coated on one surface of the UHMWPE base film, and then dried in an oven at 50°C. A composite microporous membrane with a coating thickness of 6 μm on one side was prepared.

[0052] Table 1 shows the properties of the composite microporous membrane for lithium-ion secondary batteries prepared above.

Embodiment 3

[0054] The difference between this embodiment and embodiment 1 lies in that the average particle diameter of the inorganic non-conductive insulating particles (glass frit) is 1.2 μm, which is the same as that of embodiment 1.

[0055] Table 1 shows the properties of the composite microporous membrane for lithium-ion secondary batteries prepared above.

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Abstract

A coating composition for a lithium ion secondary battery separator and a method for manufacturing the separator. The coating composition comprises a heat-resistant resin and inorganic non-conducting insulating particles, wherein the heat-resistant resin comprises the molecular chains of oleophylic structural units, hydrophilic structural units and functional group structural units, and has a thermal decomposition temperature of higher than 250°C. The inorganic non-conducting insulating particles feature high temperature resistance, low density, low rigidity and low water absorption and so on. The composite micro-porous separator prepared by the coating composition features not only a low hole closing temperature and a high separator breaking temperature, but also a low thermal shrinkage rate, high bonding force between a heat-resistant coating and a substrate, good wettability of the heat-resistant coating surface and so on; and when used as a separator of a lithium ion secondary battery, the separator has good comprehensive properties and reliable safety performance.

Description

technical field [0001] The invention relates to a coating composition for lithium-ion secondary battery diaphragms, and also relates to a manufacturing method of lithium-ion secondary battery diaphragms using the coating composition. Background technique [0002] Lithium-ion secondary batteries are widely used due to their long life and high energy density. The separator is an important part of the lithium-ion battery, which plays the role of isolating the positive and negative electrodes and ion conduction. Most of the separator materials currently on the market are polyolefin materials, mainly including polyethylene and polypropylene. [0003] Due to the difference in thermal properties between polyethylene and polypropylene, the current shutdown temperature (Shut-down temperature) of the separator made of polyethylene is relatively low. When the battery is overloaded, the microporous structure inside the separator is very fast as the temperature rises. It is destroyed a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C09D133/08C09D133/20C09D7/12H01M2/16C08F220/18C08F220/06C08F220/46C08F220/54C08J9/42C08J7/04C08L23/00C08L23/06C08J7/043C08J7/046C08J7/056C09D7/48C09D7/61H01M50/403H01M50/449H01M50/457H01M50/489H01M50/494
CPCH01M2/1686C08J7/04H01M2/145C08L23/06C08J9/42H01M10/0525H01M2/166C08F220/46C08F220/06C09D133/08C08F220/54C09D7/12C08F220/18C09D133/20C08L23/00C08F222/04C08J2323/02C08J2323/04C09D5/00C08K3/34C09D123/06C09D7/61C08J7/0427C09D7/48Y02E60/10H01M50/446H01M50/403H01M50/449C08J7/043C08J7/046C08J7/056C08F220/1804H01M50/457H01M50/489H01M50/494
Inventor 邱钧锋王松钊蔡朝辉吴耀根廖凯明
Owner 河南惠强新能源材料科技股份有限公司
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