Water-based PVDF coated lithium ion battery diaphragm and preparation method thereof

A lithium-ion battery and coating technology, which is applied in the direction of secondary batteries, battery pack components, circuits, etc., can solve the problems of uneven distribution of PVDF resin powder, affecting the performance of lithium-ion batteries, and increasing the thickness of the coating, achieving improved Rate discharge performance and cycle performance, which is conducive to industrialization and the effect of improving adhesion

Pending Publication Date: 2021-07-02
中化蓝天氟材料有限公司 +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In this method, the base material is prepared after mixing PVDF resin powder with other components. Due to the characteristics of the PVDF resin powder itself, it is difficult to distribute evenly in the base material, so that the distribution of PVDF resin powder in the obtained base material is uneven. Uniform, and further increase the coating thickness and uneven distribution after coating, so as to affect the performance of lithium-ion batteries

Method used

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  • Water-based PVDF coated lithium ion battery diaphragm and preparation method thereof
  • Water-based PVDF coated lithium ion battery diaphragm and preparation method thereof
  • Water-based PVDF coated lithium ion battery diaphragm and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0046] Weigh 95 parts of vinylidene fluoride-hexafluoropropylene copolymer emulsion by mass fraction, its solid content is 20%, 5 parts of polyethyl methacrylate emulsion, its solid content is 58%, mix uniformly and stir at room temperature for 10 minutes to obtain Mixed emulsion, the PVDF mixed emulsion is coated on both sides of a polyethylene-based film with a thickness of 15 μm and a porosity of 40% by gravure coating, and the coating speed is 20m / min; a three-stage oven is used for drying, each The temperature of the stage oven was 55°C, 70°C, and 60°C, respectively, and after drying, a water-based PVDF-coated lithium-ion battery separator was prepared. The thickness of the composite separator was 15.2 μm, and the thickness of each side coating was 0.1 μm.

Embodiment 2

[0048] Weigh 90 parts of polyvinylidene fluoride emulsion according to mass fraction, its solid content is 30%, 10 parts of polymethyl acrylate emulsion, its solid content is 40%, mix uniformly and stir at room temperature for 15 minutes to obtain mixed emulsion, adopt narrow slit type Coating method The PVDF mixed emulsion is coated on one side of a polyethylene-based film with a thickness of 20 μm and a porosity of 38%. °C, 60 °C, 55 °C, after drying, a water-based PVDF-coated lithium-ion battery separator was prepared, the thickness of the composite diaphragm was 20.2 μm, and the thickness of the coating was 0.2 μm.

Embodiment 3

[0050] Weigh 92 parts of vinylidene fluoride-hexafluoropropylene copolymer emulsion by mass fraction, its solid content is 35%, 8 parts of polybutyl methacrylate emulsion, its solid content is 48%, mix uniformly and stir at room temperature for 8 minutes to obtain Mixed emulsion, the PVDF mixed emulsion is coated on both sides of a polyethylene-based film with a thickness of 25 μm and a porosity of 45% by dip coating, and the coating speed is 30m / min; a three-stage oven is used for drying. The oven temperatures at all levels were 60°C, 80°C, and 70°C, and after drying, a water-based PVDF-coated lithium-ion battery separator was prepared. The thickness of the composite separator was 25.6 μm, and the thickness of each side coating was 0.3 μm.

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Abstract

The invention provides a water-based PVDF coated lithium ion battery diaphragm. The diaphragm comprises a base membrane and a PVDF coating which coats one side or two sides of the base membrane, the coating is prepared from a mixed emulsion, the mixed emulsion comprises a PVDF emulsion and a binder emulsion, the weight ratio of the PVDF emulsion in the mixed emulsion is 70-98%, and the weight ratio of the binder emulsion in the mixed emulsion is 2-30%. The invention also provides a preparation method of the water-based PVDF coated lithium ion battery diaphragm. The water-based PVDF coated lithium ion battery diaphragm provided by the invention is excellent in comprehensive performance, and the preparation method is simple in production process and pollution-free.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a water-based PVDF-coated lithium-ion battery diaphragm and a preparation method thereof. Background technique [0002] Since Japan’s Sony Corporation invented the world’s first commercial lithium-ion battery in 1991, it has high energy density, long cycle life, high specific power, low self-discharge rate, no memory effect, safety, reliability, and environmental protection. Features, lithium-ion batteries have achieved rapid development and are widely used in portable electronic (3C) products such as notebook computers, smart phones, tablet computers, digital cameras, and new energy vehicles, and have become an indispensable product in daily life . [0003] In the internal structure of lithium-ion batteries, the positive electrode, negative electrode, diaphragm, and electrolyte are the four core materials. Safety performances such as self-shutdown and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/417H01M50/449H01M50/403H01M10/0525
CPCH01M10/0525Y02E60/10
Inventor 郑怡磊吴于松徐煜韬许远远朱伟伟方敏
Owner 中化蓝天氟材料有限公司
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