Diaphragm and preparation method thereof, and lithium ion battery

A technology for lithium-ion batteries and diaphragms, applied in the field of inorganic-organic composite porous diaphragms and their preparation, can solve the problems of low flash point of acetone, potential safety hazards, diaphragm substrates affecting the performance of organic diaphragms, etc., to achieve high production efficiency and improve safety properties, improvement of overheating shrinkage performance and puncture strength effect

Active Publication Date: 2012-08-01
NINGDE AMPEREX TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But for NMP, due to its high boiling point, drying at high temperature (>80°C) will cause excessive thermal shrinkage of the separator substrate and affect the performance of the organic separator.
However, when acetone is used to prepare slurry, due to the low flash point of acetone, there is a great potential safety hazard

Method used

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  • Diaphragm and preparation method thereof, and lithium ion battery
  • Diaphragm and preparation method thereof, and lithium ion battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0042] The preparation of negative pole piece: take graphite as the negative electrode active material, and its weight content is 95%; With styrene-butadiene rubber (SBR) as binding agent, its weight content is 2%; With carbon black as conductive agent, its weight content is 3%; the above materials were added to deionized water and stirred evenly to make negative electrode slurry; the negative electrode slurry was evenly coated on copper foil, dried and compacted, and then cut into pieces and welded with negative electrode lugs to obtain negative electrode sheets .

[0043] Preparation of positive electrode sheet: lithium cobalt oxide (LiCoO 2 ) is positive electrode active material, and its weight content is 96%; With polyvinylidene fluoride (PVDF) as binding agent, its weight content is 2%; With carbon black as conductive agent, its weight content is 2%; Above-mentioned material Add it into N-methylpyrrolidone (NMP) and stir evenly to make a positive electrode slurry; evenl...

Embodiment 2

[0052] Different from embodiment 1 is the preparation of coating slurry:

[0053] Dilute 0.84 kg of polyacrylic acid-sodium polyacrylate aqueous solution with a mass fraction of 25% in deionized water. After mixing evenly, add 0.42 kg of vinylidene fluoride-hexafluoropropylene copolymer powder. After dispersing for 2 hours, the amount added is about 3.52 kg of SiO 2 After the powder is stirred for 1 hour, it is placed in a ball mill and ground for 1 hour, and then a sodium carboxymethyl cellulose solution with a solid content of 1.0 wt% is added to the ground slurry, wherein the degree of substitution of sodium carboxymethyl cellulose is 0.6, and the 1% aqueous solution The viscosity was 3000mPa·s, and the stirring was continued for 1h to obtain a coating slurry. The coating slurry had a viscosity of 300 mPa·s and a pH of 4.0.

[0054] Among them, SiO 2 The specific surface area is 4m 2 / g, the particle size D50 is 2.5 μm.

[0055] And the thickness of the single-layer ac...

Embodiment 3

[0058] Different from embodiment 1 is the preparation of coating slurry:

[0059] Dilute 2.52 kg of 25% polyacrylic acid-sodium polyacrylate aqueous solution in deionized water, mix well and add 0.42 kg of polyvinylidene fluoride-hexafluoropropylene powder. After dispersing for 2 hours, add about 3.1 kg of TiO 2 and Al 2 o 3 The mixture (the mass ratio of the two is 1:1) powder is stirred for 1h and then placed in a ball mill for grinding for 1h, and then a sodium carboxymethyl cellulose solution with a solid content of 1.0wt% is added to the slurry after grinding, wherein carboxymethyl The degree of substitution of cellulose sodium is 1.0, the viscosity of 1% aqueous solution is 2000mPa·s, and the stirring is continued for 1h to prepare the coating slurry. The coating slurry had a viscosity of 50 mPa·s and a pH of 4.5.

[0060] And the thickness of the single-layer active coating on the porous membrane substrate is 5 μm.

[0061] Among them, TiO 2 The specific surface ar...

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Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to an inorganic and organic composite multihole diaphragm. The diaphragm comprises a multihole diaphragm base material and an active coating layer attached to at least one surface of the multihole diaphragm base material, wherein the active coating layer comprises inorganic particles, vinylidene fluoride and hexafluoropropylene copolymer, cellulose based polymer with the molecular weight of 100,000 to 1,000,000 and at least one of polyacrylic acid and polyacrylate. Compared with the prior art, the diaphragm keeps relatively high air permeability and lithium ion transmission capacity; the active coating layer and the multihole diaphragm base material are well bonded; and the overheating contraction performance and the puncture strength of a diaphragm base can be improved remarkably. Furthermore, the invention also discloses a preparation method for the diaphragm and a lithium ion battery with the diaphragm.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to an inorganic-organic composite porous diaphragm, a preparation method thereof, and a lithium ion battery comprising the diaphragm. Background technique [0002] Lithium-ion batteries have been widely used as power sources for various mobile devices since their commercialization due to their advantages such as high energy density, high operating voltage, no memory effect, and long cycle life. With the large-scale application of lithium-ion batteries, their safety issues have become increasingly prominent. [0003] Currently, lithium-ion batteries generally use polyolefin-based separators. However, since such polyolefin-based separators have a melting point of 200° C. or lower, they have a drawback that when the temperature of the battery increases due to internal and / or external factors, the separator shrinks or melts, causing positive electrode tabs and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M10/0525
CPCY02E60/122Y02E60/10
Inventor 邓耀明许瑞柳娜王正
Owner NINGDE AMPEREX TECH
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