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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.

Inactive Publication Date: 2015-08-19
东莞市魔方新能源科技有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In this invention, the non-swellable part of the polymer needs to support a certain skeleton space to allow the expansion of the pole piece, and at the same time, the swollen part of the polymer needs to be bonded to the pole piece. The bonding polymer with only one degree of swelling cannot play a good role. These two functions

Method used

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  • Isolating membrane for lithium ion secondary battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] 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:

[0040] A polyethylene microporous film with a thickness of 9 μm was used as the main body of the isolation membrane.

[0041] Preparation of Adhesive Polymer Coating:

[0042] Stir polyvinylidene fluoride-hexafluoropropylene with 80% swelling degree and polyvinylidene fluoride-hexafluoropropylene with 30% swelling degree and polyacrylate solution in water for 4 hours to form a uniform slurry, and 80% swelling degree The weight ratio of polyvinylidene fluoride-hexafluoropropylene and 30% swelling degree of polyvinylidene fluoride-hexafluoropropylene and polyacrylate is 30:50:20, the solid content of the slurry is 30%, and it is printed by screen printing The polymer ...

Embodiment 2

[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] Isolation film:

[0046] A polyimide with a thickness of 9 μm is used as the isolation membrane body.

[0047] Preparation of polymer coating:

[0048] Stir polyvinylidene fluoride-hexafluoropropylene with 90% swelling degree, polyacrylonitrile and styrene-butadiene polymer with 30% swelling degree in water for 4 hours to form a uniform slurry, and 90% swelling degree The weight ratio of polyvinylidene fluoride-hexafluoropropylene to polyacrylonitrile and styrene-butadiene polymer with a swelling degree of 30% is 20:65:15, and the solid content of the slurry is 35%. The polymer solution was coated on both sides of the isolation film with a thickness of 4um, ...

Embodiment 3

[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] Isolation film:

[0052] A polypropylene microporous film with a thickness of 9 μm was used as the isolation membrane body.

[0053] Preparation of polymer coating:

[0054] Stir together polyoxyethylene with 90% swelling degree, 80% vinylidene fluoride-hexafluoropropylene, 40% swelling degree vinylidene fluoride-hexafluoropropylene and sodium carboxymethyl cellulose in water for 4 hours to form a uniform slurry Material, polyoxyethylene with 90% swelling degree, 80% vinylidene fluoride-hexafluoropropylene and 40% swelling degree vinylidene fluoride-hexafluoropropylene and the weight ratio of carboxymethyl cellulose sodium are 10:10: 70:10, the solid content...

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Abstract

The invention belongs to the technical field of battery manufacture, and specifically relates to an isolating membrane for a lithium ion secondary battery, comprising an isolating membrane main body, wherein at least one surface of the isolating membrane main body is coated with a binder-polymer coating, and the binder-polymer coating comprises a binder polymer and a binder, and the binder-polymer coating at least comprises two polymers with different swelling degrees, wherein at least one polymer with lower swelling degree is used as cage construction for holding a certain expansion space for a pole piece of the lithium ion battery, and at least one polymer with higher swelling degree can be well bonded with the pole piece. Because the binder-polymer coating comprises the binder polymer and the binder, and the system is an environmental water system, and the coating coverage rate is 10 percent to 90 percent, the isolating membrane for the lithium ion secondary battery not only can be used for providing the expansion space of the pole piece, but also has small blockage for the hole of the isolating membrane, which cannot have influence on the battery performance. The polymer with high swelling degree can be well bonded with the pole piece so as to effectively restrain 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] Lithium-ion secondary batteries are widely used in consumer electronics products, such as mobile phones, notebook computers, tablet computers, Bluetooth headsets, MP3, digital cameras and other fields have been widely used. With the increasingly serious problems of environmental pollution and energy crisis, the use of lithium-ion secondary batteries in power batteries and stationary power stations is becoming more and more popular. [0003] With the continuous improvement of energy density, the use of high-capacity anode materials leads to serious expansion during charging and discharging, resulting in battery distortion. In order to solve this problem, a bonding polymer coating is applied to the surface of the separator, or a bonding polymer coating is applie...

Claims

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Application Information

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IPC IPC(8): H01M2/18H01M2/16H01M10/0525H01M50/417H01M50/431H01M50/489H01M50/491
CPCY02E60/10
Inventor 蒋中林
Owner 东莞市魔方新能源科技有限公司
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