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Isolating membrane for lithium ion secondary battery

A secondary battery and separator technology, applied in secondary batteries, battery components, circuits, etc., can solve the problems of complex process, difficult process control, complex process, etc., to improve thermal stability, suppress deformation, The effect of inhibiting shrinkage

Active Publication Date: 2015-09-30
东莞市魔方新能源科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Patents CN102569701A and CN102610773A are achieved by first forming an insulating layer of inorganic particles, and then coating a polymer bonding layer. Multiple coatings are required, and the process is relatively complicated and difficult to control.
Chinese patent CN103441230A is achieved through a process of mixing inorganic particles and bonding polymers, but it needs to be heated and pre-swelled, and the process is more complicated
Chinese patent CN101326658A forms a gradient change in the content ratio of the binder polymer / inorganic particles on the surface of the porous substrate by multiple coatings, and the process is also very complicated

Method used

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  • Isolating membrane for lithium ion secondary battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] The preparation of the positive electrode sheet, the negative electrode sheet and the battery of this embodiment are the same as those of Comparative Example 1, and will not be repeated. The separator is different from Comparative Example 1. The separator and its preparation are described in detail below:

[0045] A polyethylene microporous film with a thickness of 9 μm was used as the main body of the isolation membrane.

[0046] Preparation of functional coating slurry:

[0047] 1) Add Al to deionized water first 2 o 3The particles were stirred for 1h, the solid content was 40wt%, and then ground in a ball mill for 1h, then added to the acrylate emulsion (the content of polyacrylate in the aqueous solution was 25wt%) and stirred for 1h, the mass ratio of Al2O3 to acrylate was 80:20, Then add polyvinylidene fluoride-hexafluoropropylene powder and stir for 2h, Al 2 o 3 The mass ratio of polyvinylidene fluoride-hexafluoropropylene is 50:50, the solid content of the s...

Embodiment 2

[0050] The preparation of the positive electrode sheet, the negative electrode sheet and the battery of this embodiment are the same as those of Comparative Example 1, and will not be repeated. The separator is different from Comparative Example 1. The separator and its preparation are described in detail below:

[0051] A polyimide with a thickness of 9 μm is used as the isolation membrane body.

[0052] Preparation of functional coating slurry:

[0053] 1) First add boehmite particles into deionized water and stir for 1 hour, the solid content is 30wt%, then grind in a ball mill for 1 hour, then add polyacrylonitrile emulsion (the content of polyacrylonitrile in the aqueous solution is 20wt%) and stir for 1 hour, The mass ratio of boehmite to polyacrylonitrile is 90:10, then polyoxyethylene powder is added and stirred for 2 hours, the mass ratio of boehmite to polyoxyethylene is 80:20, and the solid content of the slurry is 33wt% , the average particle size of boehmite part...

Embodiment 3

[0056] The preparation of the positive electrode sheet, the negative electrode sheet and the battery of this embodiment are the same as those of Comparative Example 1, and will not be repeated. The separator is different from Comparative Example 1. The separator and its preparation are described in detail below:

[0057] A polypropylene microporous film with a thickness of 9 μm was used as the isolation membrane body.

[0058] Preparation of functional coating slurry:

[0059] 1) Add TiO to the mixed solvent of ethanol and deionized water (the mass of ethanol and deionized water is 50:50) 2 The particles were stirred for 1 h, the solid content was 30 wt%, and then ground in a ball mill for 1 h, then added sodium carboxymethyl cellulose solution (concentration of sodium carboxymethyl cellulose solution was 1.5 wt%) and stirred for 1 h, TiO 2 The mass ratio with sodium carboxymethyl cellulose is 95:5, then add polymethacrylate (PMMA) powder and stir for 2h, TiO 2 The mass rati...

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Abstract

The invention belongs to the technical field of battery manufacture and in particular relates to an isolating membrane for a lithium ion secondary battery. According to the isolating membrane, at least one surface of an isolating membrane body is coated with a functional coating layer; the functional coating layer is formed in a manner that inorganic particles, a binder and a polymer are mixed and stirred in a solvent to form slurry, and at least one surface or two surfaces of the isolating membrane body is / are coated with the slurry; and the coating process of the functional coating layer is controlled by adopting a process, so as to enable an inorganic particle layer to be enriched on the surface of the isolating membrane body, and the polymer to be enriched on the surfaces of the inorganic particles. The inorganic particles in the functional coating layer have the excellent heat stability, so that the shrinking of the isolating membrane under a high temperature condition is inhibited, and the heat stability of the isolating membrane is improved; and simultaneously a polymer layer enriched on the surfaces of the inorganic particles can be bonded together with electrode pieces of the lithium ion secondary battery in the lithium ion secondary battery so as to inhibit the deformation of the battery.

Description

technical field [0001] The invention belongs to the technical field of battery isolation membranes, and in particular relates to an isolation membrane for lithium-ion secondary batteries. Background technique [0002] The separator of the lithium-ion secondary battery is used as the isolation of the positive and negative electrodes, and is sandwiched between the positive and negative electrodes. The main function is to prevent the short circuit from direct contact between the positive and negative electrodes. At present, the separator is mainly composed of polyethylene, polypropylene and other polyolefin porous media. The polyolefin separator has a melting point below 200°C. , The separator is prone to heat shrinkage, resulting in a larger short circuit between the positive and negative electrodes, resulting in thermal runaway of the battery and causing a fire accident. In addition, as the energy density of lithium-ion secondary batteries continues to increase, the graphite...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M2/14H01M50/403H01M50/431H01M50/449H01M50/491
CPCH01M10/0525H01M50/446H01M50/403Y02E60/10
Inventor 蒋中林
Owner 东莞市魔方新能源科技有限公司
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