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Water-based multi-layer membrane for lithium ion battery

A technology for lithium-ion batteries and diaphragms, applied in secondary batteries, battery pack components, separators/films/diaphragms/spacers, etc., can solve problems such as melting, peeling, and volume changes of diaphragms

Inactive Publication Date: 2015-08-26
SHANGHAI ENERGY NEW MATERIALS TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The separator used in lithium-ion batteries is generally a polyolefin-based microporous membrane. Since the melting point of this polyolefin-based microporous membrane is lower than 150°C, it is prone to the following defects: When the battery temperature rises due to internal or external factors When the diaphragm shrinks or melts, the volume of the diaphragm changes
Due to the low cost of water-based slurry with binary components, some manufacturers have begun to use this processing method; however, the coated diaphragm processed by this method has softness in the diaphragm and hard coating, resulting in poor compatibility between layers. , the flexibility cannot be satisfied, and it is easy to cause the overall peeling and powder dropping phenomenon, which has great hidden dangers to battery processing and safety
[0005] In addition, some manufacturers use water-based materials for coating, but they cannot guarantee the adhesion performance between them and the positive and negative electrodes, resulting in poor consistency of the battery, which ultimately affects the safety performance of the battery

Method used

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  • Water-based multi-layer membrane for lithium ion battery
  • Water-based multi-layer membrane for lithium ion battery
  • Water-based multi-layer membrane for lithium ion battery

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1-8

[0162] The preparation steps of water-based multilayer diaphragm are as follows:

[0163] 1) Select Enjie to produce ND9 series PE microporous base membrane;

[0164] 2) The PE microporous base film is passed through the MCD type coating machine (purchased from Fuji Machinery Industry Co., Ltd.), and the water-based inorganic particle slurry described in the following table 1 is coated on the PE microporous film through gravure printing, And finally after baking in an oven, a PE microporous membrane covered with an inorganic coating can be obtained;

[0165] 3) Pass the obtained PE microporous membrane covered with inorganic coating through the coating machine, and at the same time apply the water-based organic particle slurry shown in Table 1 on the intermediate product of the inorganic coating through gravure printing, and after drying After baking and shaping, the final water-based multilayer separator can be obtained.

[0166] Table 1

[0167]

[0168]

[0169] ...

Embodiment 9

[0173] Embodiment 9: test result

[0174] Embodiment 1-8 and comparative example 1 are tested, and the results are as follows:

[0175]

[0176] where MD means longitudinal direction;

[0177] TD means landscape orientation.

[0178] It can be seen from the test results that when the two coating structures are used at the same time, it can not only meet the high temperature resistance of the separator, but also meet the bonding performance of the positive and negative electrodes and the separator, so that while meeting the performance of the battery separator, it can also meet the requirements of the battery. Consistent processing requirements.

Embodiment 10-13 and comparative example 2

[0179] Examples 10-13 and Comparative Example 2: Preparation of lithium-ion batteries

[0180] In this embodiment, the lithium-ion battery is composed of a positive electrode system, a negative electrode system, and an electrolyte system, wherein lithium manganate is used in the positive stage, graphite is used in the negative electrode, the electrolyte solution is an EC / EMC system, and the lithium salt concentration is (LiPF 6 ) is 1mol / L. Preparation process: the positive electrode is composed of lithium manganate and PVDF in a weight ratio of 100:3, and the negative electrode is composed of graphite, carboxymethyl cellulose (CMC), styrene-butadiene rubber emulsion in a weight ratio of 100:2:3 and PVDF shown in the table below -HFP composition. NMP is used as the solvent for the positive electrode, and water is used as the solvent for the negative electrode, and positive and negative electrode slurries are made respectively, and the separator shown in the table below is use...

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Abstract

The invention provides a water-based multi-layer membrane for a lithium ion battery. The water-based multi-layer membrane comprises a polymer membrane substrate (A), an inorganic or organic particle coating (B) coating one or two sides of the polymer membrane substrate (A), and an organic particle coating (C) coating the inorganic or organic particle coating (B), wherein the inorganic or organic particle coating (B) is formed by a composition which comprises 15-70wt% of inorganic or organic particles and 30-85wt% of water; the inorganic or organic particles are selected from aluminum oxide, silica, barium sulfate, boehmite or polyimide; the organic particle coating (C) is formed by a composition which comprises 5-30wt% of organic particles and 70-95wt% of water; and the organic particles are selected from polyvinylidene fluoride-hexafluoropropylene, polyacrylonitrile, polyoxyethylene or polymethyl methacrylate.

Description

technical field [0001] The invention relates to a diaphragm for a lithium ion battery and a lithium ion battery using the diaphragm, in particular to an aqueous multilayer diaphragm for the lithium ion battery and a lithium ion battery using the diaphragm. Background technique [0002] Due to its good chemical stability and excellent physical properties, microporous polyethylene film is widely used in secondary lithium-ion batteries, such as: mobile phone batteries, notebook batteries, power tool batteries and power car batteries. In the lithium-ion battery, the main function of the separator is to separate the positive and negative electrodes of the battery and prevent short circuit caused by contact between the two electrodes. It is one of the key inner components. The performance of the separator determines the interface structure and internal resistance of the battery, which directly affects the capacity, cycle and safety performance of the battery. A separator with exce...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M50/411H01M50/417H01M50/443H01M50/457
CPCH01M10/0525H01M50/409Y02E60/10
Inventor 程跃李英王伟强苏晓明徐建峰
Owner SHANGHAI ENERGY NEW MATERIALS TECH CO LTD
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