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Battery diaphragm and preparation method thereof, and lithium ion battery containing diaphragm

A technology of battery diaphragm and diaphragm, which is applied in the direction of secondary battery, battery pack parts, secondary battery repair/maintenance, etc. It can solve the problem of easy puncture, high porosity, and poor liquid absorption and liquid retention capacity of polyolefin diaphragm and other problems, to achieve the effect of improving mechanical properties and heat resistance, high mechanical strength, and good corrosion resistance

Inactive Publication Date: 2019-06-04
JIANGSU TAFEL NEW ENERGY TECH CO LTD +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the lithium-ion battery separators we use commercially are generally single-layer polyethylene separators, single-layer polypropylene separators, or polyethylene / polypropylene composite separators. Although polyolefin separators have better acid and alkali resistance, higher Tensile strength, higher porosity and other properties, but the polyolefin separator still has the following shortcomings: 1) The melting point of polyethylene is about 140 ° C, and the melting point of polypropylene is about 160 ° C. When the local temperature of the battery rises to its melting point In the above cases, a short circuit may occur due to the contact of the positive and negative electrodes of the battery due to the fusing of the diaphragm, and the high temperature thermal stability of the diaphragm still needs to be improved; Safety accident; 3) Polyolefin diaphragm has poor liquid absorption and liquid retention capacity

Method used

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  • Battery diaphragm and preparation method thereof, and lithium ion battery containing diaphragm
  • Battery diaphragm and preparation method thereof, and lithium ion battery containing diaphragm

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Preparation of positive electrode sheet:

[0029] Lithium cobaltate, conductive agent superconducting carbon (Super-P), and binder polyvinylidene fluoride (PVDF) were mixed uniformly at a mass ratio of 97:1.5:1.5 to make a lithium-ion battery cathode slurry with a certain viscosity. The slurry is coated on the aluminum foil of the current collector, and then cold pressed after drying at 85°C; then edge trimming, cutting, and slitting are performed, and after slitting, dry at 110°C for 4 hours under vacuum conditions, and weld the tabs. Made into lithium-ion battery cathode sheet.

[0030] Preparation of negative electrode sheet:

[0031] Make a slurry of graphite and conductive agent superconducting carbon (Super-P), thickener sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) at a mass ratio of 96:2.0:1.0:1.0 , coated on the current collector copper foil and dried at 85°C, trimmed, cut into pieces, slitting, and dried at 110°C for 4 hours...

Embodiment 2

[0039] Different from Example 1 is the preparation of diaphragm:

[0040] 1) Mix glass fibers with a diameter of 0.3 μm and polymethacrylic acid accounting for 6% of the glass fiber mass, add deionized water and stir evenly to form a slurry. The viscosity of the slurry is 2500mPa·s, and the solid content of the slurry is 45%;

[0041] 2) Coating and forming the slurry obtained in 1), dehydrating and drying to obtain a diaphragm base layer, the thickness of the diaphragm base layer is 10 μm, and the porosity of the diaphragm base layer is 42%;

[0042]3) Add polystyrene to NMP solvent, then add polymethyl acrylate, stir evenly, and apply spray coating or gravure coating on the base layer of the diaphragm to form a hot-melt polymer layer. The hot-melt polymer The coating mass of the layer is 0.6% of the mass of the base layer of the separator, and the thickness of the hot-melt polymer layer is 4 μm.

[0043] The rest are the same as in Embodiment 1, and will not be repeated he...

Embodiment 3

[0045] Different from Example 1 is the preparation of diaphragm:

[0046] 1) Mix glass fibers with a diameter of 0.4 μm and polymethyl acrylate accounting for 7% of the glass fiber mass, add deionized water and stir evenly to form a slurry. The viscosity of the slurry is 3000mPa·s, and the solid content of the slurry is 50%;

[0047] 2) Coating and forming the slurry obtained in 1), dehydrating and drying to obtain a diaphragm base layer, the thickness of the diaphragm base layer is 11 μm, and the porosity of the diaphragm base layer is 45%;

[0048] 3) Add polyvinyl chloride to NMP solvent, then add polyethyl acrylate, stir evenly, and apply spray coating or gravure coating on the base layer of the diaphragm to form a hot-melt polymer layer. The hot-melt polymer The coating mass of the layer is 0.7% of the mass of the base layer of the separator, and the thickness of the hot-melt polymer layer is 5 μm.

[0049] The rest are the same as in Embodiment 1, and will not be repea...

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Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a battery diaphragm. The battery diaphragm includes a diaphragm base layer and a hot-melt polymer layer arranged on at least one surface of the diaphragm base layer. The diaphragm base layer includes at least one of glass fibers and ceramic fibers, and first adhesive. The hot-melt polymer layer includes a hot-melt polymer and second adhesive. Compared with the prior art, the diaphragm has better thermal stability, higher mechanical strength and stronger liquid retention and absorption capacity. In addition, the invention provides a preparation method of the battery diaphragm and a lithium ion battery containing the diaphragm.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a battery diaphragm, a preparation method thereof and a lithium ion battery comprising the diaphragm. Background technique [0002] Lithium-ion battery is a new chemical power system developed rapidly in recent years. Compared with traditional nickel-cadmium or nickel-hydrogen batteries, it has the advantages of high specific energy, long cycle life, no memory effect and fast charging and discharging. It is widely used In portable electronic products, electric vehicles and hybrid vehicles, etc. [0003] Lithium-ion batteries are usually mainly composed of positive electrodes, negative electrodes, separators, electrolytes, and battery casings. In the lithium-ion battery structure, the separator is one of the key inner components. The main function of the diaphragm is to separate the positive and negative electrodes of the battery, prevent the positive a...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M2/14H01M10/0525H01M10/42
CPCY02E60/10
Inventor 宋贺华秉杨林沃荣梁正峰黄天翔
Owner JIANGSU TAFEL NEW ENERGY TECH CO LTD
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