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Composite membrane for lithium ion secondary battery, manufacturing method of composite membrane and electrochemical device containing membrane

A technology for secondary batteries and composite diaphragms, which is applied in the field of composite diaphragms for lithium-ion secondary batteries and electrochemical devices. It can solve problems such as fire, thermal shrinkage of the diaphragm, and thermal runaway of the battery. It achieves simple operation, excellent safety performance, and excellent performance. The effect of electrochemical performance

Active Publication Date: 2014-09-24
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

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. Extremely prone to heat shrinkage, leading to a larger short circuit between the positive and negative electrodes, leading to thermal runaway of the battery and causing fire accidents

Method used

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  • Composite membrane for lithium ion secondary battery, manufacturing method of composite membrane and electrochemical device containing membrane
  • Composite membrane for lithium ion secondary battery, manufacturing method of composite membrane and electrochemical device containing membrane
  • Composite membrane for lithium ion secondary battery, manufacturing method of composite membrane and electrochemical device containing membrane

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preparation example Construction

[0038] A preparation method for a composite diaphragm for a lithium ion secondary battery, comprising the following steps:

[0039] a) Dissolve the binder in a solvent to form a binder solution, add inorganic particles to the binder solution corresponding to different porous insulating layers, and mix evenly to prepare a slurry for each layer of porous insulating layer; the solvent is tetrahydrofuran , methyl ethyl ketone, dimethyl formamide, dimethyl acetamide, tetramethyl urea, tetramethyl phosphate, acetone, dichloromethane, chloroform, dimethylamide, N-methylpyrrolidone, cyclohexane, water , any one or a combination of several alcohols;

[0040] b) Add different amounts of pore-forming agents to the slurries corresponding to different porous insulating layers to form the final slurry of each layer of porous insulating layer; the final slurry formed by binder, inorganic particles and pore-forming agent The mass percent concentration of the mixture is 20-70wt%, preferably 3...

Embodiment 1

[0058] The preparation method of the positive and negative electrodes is the same as that of Comparative Example 1, and will not be described below.

[0059] Porous diaphragm: A polyethylene microporous film with a thickness of 9 μm is used as the porous diaphragm.

[0060]Preparation of porous insulating layer 1: first add 40wt% polyacrylate emulsion (the content in aqueous solution is 40wt%) to deionized water and stir for 1 hour, then add 55wt% Al 2 o 3 Particles (average particle size is 0.5 μm, particle size distribution is 0.1 ~ 3.5um) are stirred for 2 hours, and then ground in a ball mill for 1 hour, and then 5 wt % ammonium bicarbonate is added to the ground slurry, and stirring is continued for 1 hour to prepare a slurry. The solid content is 30wt%. Then use gravure coating to uniformly cover the prepared slurry on one surface of a 9 μm polyethylene microporous film with a coating thickness of 4 μm, and set aside.

[0061] Preparation of porous insulating layer 2:...

Embodiment 2

[0065] Porous diaphragm: A polyethylene microporous film with a thickness of 9 μm is used as the porous diaphragm.

[0066] Preparation of porous insulating layer 1: first add 15wt% polyacrylate emulsion (40wt% in aqueous solution) to deionized water and stir for 1 hour, then add 75wt% Al 2 o 3 After the particles (average particle size is 0.5 μm, particle size distribution is 0.1~3.5um) are stirred for 2 hours, they are ground in a ball mill for 1 hour, and then 10 wt% of ammonium bicarbonate is added to the ground slurry, and the stirring is continued for 1 hour to prepare a slurry. The solid content is 30wt%. Then use gravure coating to uniformly cover the prepared slurry on one surface of a 9 μm polyethylene microporous film with a coating thickness of 1 μm, and set aside.

[0067] Preparation of porous insulating layer 2: first add 15wt% polyacrylate emulsion (40wt% in aqueous solution) to deionized water and stir for 1 hour, then add 60wt% Al 2 o 3 After the particle...

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Abstract

The invention discloses a composite membrane for a lithium ion secondary battery. The composite membrane comprises a porous membrane and a plurality of porous insulating layers, wherein at least one surface of the porous membrane is covered by the porous insulating layers, the hole diameters of the porous insulating layers are distributed from small to large in a gradient manner from the porous membrane to the direction of a pole piece, and the porous insulating layers contain inorganic particles and binding agents. The invention further discloses a preparation method of the composite membrane. The preparation method comprises the following steps: firstly, mixing and dispersing the inorganic particles, the binding agents and a hole forming agent in a solvent to obtain slurry, coating the surface of the porous membrane with the slurry, and drying to obtain the composite membrane. The invention further discloses an electrochemical device containing the composite membrane. According to the composite membrane, the preparation method of the composite membrane and the electrochemical device which are disclosed by the invention, the composite membrane has the advantages of good thermostability, low thermal shrinkage, excellent safety performance and good electrochemical performance, the preparation method of the composite membrane has the advantages of simplicity in operation and convenience, and the electrochemical device has excellent safety performance and good electrochemical performance.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion secondary batteries, and in particular relates to a composite diaphragm for lithium-ion secondary batteries, a manufacturing method thereof and an electrochemical device containing the diaphragm. Background technique [0002] Due to the characteristics of high energy density, high working voltage and light weight, lithium-ion secondary batteries have been widely used in consumer electronics products, such as mobile phones, notebook computers, tablet computers, Bluetooth headsets, MP3, digital cameras and other fields. With the increasingly severe environmental pollution and energy crisis, the use of lithium-ion secondary batteries in power batteries and stationary power stations has become more and more popular, but the safety of lithium-ion secondary batteries has always been the focus of attention. [0003] The diaphragm of the lithium-ion secondary battery is used as the isolation of the po...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/18H01M50/40H01M50/446
CPCH01M10/0525H01M50/446H01M50/403H01M50/463Y02E60/10
Inventor 蒋中林
Owner 东莞市魔方新能源科技有限公司
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