Microporous polymer isolating film for Li-ion battery and method for producing the same

一种微孔聚合物、锂离子电池的技术，应用在二次电池、电池组零部件、非水电解质蓄电池等方向，能够解决膜片涂层凹凸不平、局部电压升高、电流分布不均等问题，达到吸液速度快、高吸液率、亲水性好的效果

Active Publication Date: 2008-07-02
CHENGDU ZHONGKE LAIFANG POWER SCI & TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During the drying and use of the diaphragm in this composite method, due to vibration, bending, and folding, powder shedding will inevitably occur, resulting in uneven coating of the diaphragm. When the battery is charged and discharged, due to uneven current distribution, local voltage rise, may cause current breakdown phenomenon

Method used

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  • Microporous polymer isolating film for Li-ion battery and method for producing the same
  • Microporous polymer isolating film for Li-ion battery and method for producing the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0036] Embodiment 1 Preparation of microporous polymer membrane of the present invention

[0037] Synthesis of the first step polymer colloidal emulsion

[0038] In this example, the hydrophilic polymer polyvinyl alcohol (PVA) 1750 and the lipophilic monomer vinyl acetate (VAC) / ethyl acrylate (EA) / acrylonitrile (AN) were grafted and copolymerized in the water phase to prepare Aqueous polymer emulsion for lithium battery diaphragm, its copolymer composition is PVA: VAC: EA: AN=10: 2: 2: 5 (weight ratio, the same below), the copolymer content is 17%, and the product is a white opaque emulsion .

[0039] The specific preparation method of the polymer emulsion is: in a four-port reaction vessel with condensed water, add 1000g of distilled water and 100g of polyvinyl alcohol (PVA) 1750; After 3 hours, when the material is transparent, it can be considered as complete dissolution, turn off the heating, and cool naturally to 55°C. Add 40g of a 1:1 blend of lipophilic monomer vinyl...

Embodiment 2

[0045] Example 2 Preparation of Microporous Polymer Diaphragm of the Present Invention

[0046] Synthesis of the first step polymer colloidal emulsion

[0047] The reaction steps are basically the same as in Example 1, except that the lipophilic monomer ethyl acrylate (EA) is replaced by acrylamide (AM) with good hydrophilicity, and its copolymer composition is PVA: VAC: AM: AN=10 :2:1:8.

[0048] The specific preparation method of the polymer emulsion is: all the monomers are added in a one-time feeding method, the material concentration is adjusted to about 13%, and the initiator is directly added, and the slurry quickly passes through the process of colorless-light blue-white milky, Faster than Example 1. After 12 hours of reaction, the material was discharged to obtain the polymer diaphragm emulsion for lithium batteries.

[0049] The second step slurry equipment

[0050] The proportion of the filler added is the same as in Example 1, and the materials are titanium dio...

Embodiment 3

[0053] Synthesis of the first step polymer colloidal emulsion

[0054] In this example, polyvinyl alcohol 1788 (PVA) is added with lipophilic monomer styrene (St) / butyl acrylate (Ba) / acrylonitrile (AN) to carry out ternary copolymerization in the aqueous phase to prepare a lithium battery separator The aqueous polymer emulsion, its copolymer composition is PVA: St: Ba: AN=10: 2: 4: 5 (weight ratio, the same below), the copolymer content is 17%, and the product is white opaque emulsion.

[0055] The polymer emulsion adopts step-by-step polymerization: in a four-port reaction vessel with condensed water, add 1000g of distilled water and 100g of polyvinyl alcohol (PVA) 1799, the reaction kettle is heated to 90 degrees, stirred and dissolved, and the speed is 100 rpm. After 3 hours, when the material is transparent, it can be considered that the dissolution is complete, turn off the heating, and cool naturally to the reaction temperature of 65°C. Add styrene (St) monomer and ...

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Abstract

The invention relates to a diaphragm used for power maintaining device as a lithium ion secondary battery and a preparation method thereof, which belongs to a field of manufacturing battery and capacitor. The diaphragm of the invention takes water as reaction medium; polymers colloid and emulsion are obtained through polymerization reaction generated by polyvinyl alcohol, hydrophobic monomer and hydrophilic monomer with an initiator in water solution; by adopting tape-casting and coating process, the polymers colloid and emulsion are coated on a plastic baseband; the diaphragm is obtained through stripping after drying. The diaphragm has good liquid absorbability, high liquid absorption rate and retention, low resistivity, good mechanical strength and good thermal stability (little thermal shrinkage and little size distortion) as well as electrochemical stability; and the prepared lithium ion battery is characterized by good cycle stability and long service life.

Description

technical field [0001] The invention relates to a diaphragm material used for energy storage devices such as lithium-ion secondary batteries and a preparation method thereof, belonging to the field of battery and capacitor manufacturing. Background technique [0002] Microporous polymer membrane is one of the three indispensable materials for the manufacture of lithium-ion batteries. The material properties, microporous structure, and physical and chemical properties used in it are closely related to the electrical performance, safety and cycle life of lithium-ion batteries. The separators used in traditional liquid batteries are mainly microporous polyolefin membranes, microporous polyvinylidene fluoride membranes, and microporous polyolefin membrane / polyvinylidene fluoride composite membranes. [0003] Microporous polyolefin membrane: including polyethylene / polypropylene / polyethylene propylene composite membrane. Using mechanical biaxial stretching (dry method) and solven...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16C08J5/22H01M10/36H01M50/403H01M50/411H01M50/414H01M50/489H01M50/491H01M50/497
CPCC08J5/2231Y02E60/122H01M10/056H01M10/0565H01M2/1653H01M2300/0082H01M10/0525C08J2333/08Y02E60/10H01M50/414H01M50/489C08J5/22H01M50/403H01M50/491H01M50/446H01M50/431H01M50/417H01M50/443Y02P70/50
Inventor 邓正华潘中来李仁贵王璐邓佳闽杜鸿昌高建东索继栓
Owner CHENGDU ZHONGKE LAIFANG POWER SCI & TECH CO LTD
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