Lithium-ion battery diaphragm and preparation method thereof

A lithium-ion battery and diaphragm technology, which is applied to battery components, circuits, electrical components, etc., can solve problems such as no shutdown function, unfavorable usability, and impact on battery performance

Inactive Publication Date: 2015-12-09
郑少华
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In view of the lack of high-temperature dimensional stability of general-purpose polyolefin battery separators, it was proposed to use polyimide to prepare battery separators, which have excellent temperature resistance, but do not have a shutdown function
In addition, some people apply a thin layer of inorganic coating on the surface of polyolefin. Such a coating has poor adhesion to the sheet substrate. The ceramic layer and the substrate are only bonded by the adhesive in the ceramic layer. The junction strength is weak. During the process of processing the separator, winding the electrode group and charging and discharging the battery, the coating particles are prone to fall off, which affects the temperature resistance of the battery separator. Inhomogeneity of performance affects the consistency of battery performance
[0004] At present, the vast majority of lithium-ion battery separators are polyolefins, usually polypropylene or polyethylene or a combination of the two. Due to the large difference in polarity between polyolefins and the electrolyte, the wettability of the battery fluid to the separator is low. Low ionic conductivity seriously affects the performance of the battery
With the development of new energy technology, especially the development of high-current power lithium-ion batteries, higher requirements are put forward for the pore size and distribution of the separator, the wettability of the electrolyte, and high-temperature resistance. Pure polyolefin separators Can no longer meet the needs of lithium-ion battery use and safety
The existing production process of lithium-ion battery diaphragm, whether it is "wet" or "dry", is limited by the process conditions, it is difficult to produce microporous materials with uniform pore size, and the selection of materials is also greatly restricted. limits
Due to the need to stretch the film, the "wet" and "dry" produced separators have a large shrinkage, which is not good for the final use, and the excellent rate of production is low

Method used

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  • Lithium-ion battery diaphragm and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0061] Lithium-ion battery separators were prepared by single-layer coating with the structure as figure 1 As shown, 1 is the coating, 2 is the porous substrate, the total thickness is 12 μm, the porosity is 48%, the thermal closing temperature is 125°C, and the liquid absorption rate is 180%.

[0062] A single-layer 7μm polyethylene diaphragm substrate is selected, with a melting point of 125°C, a porosity of 60%, and a liquid absorption rate of 50%.

[0063] The production steps are as follows:

[0064] a. The coated surface of the polyethylene diaphragm substrate is treated with corona, and the surface tension is 42dyn / cm.

[0065] b. Coating preparation:

[0066] The components of slurry A-1 include: 1 part of silane coupling agent (KH570), 10 parts of ethyl acetate, 19 parts of nano silicon dioxide (nano-SiO 2 ), 20 parts of propoxylated trimethylolpropane triacrylate (TMP3POTA), 10 parts of polyethylene glycol 1000 (PEG-1000), 10 parts of polyethylene glycol 200 (PEG-...

Embodiment 2

[0075] Preparation of Li-ion battery separator by single-sided two-layer stack coating, structure figure 2 As shown, 3 and 4 are coatings, 5 is a porous substrate, the total thickness is 20 μm, the porosity is 40%, the thermal closing temperature is 129°C, and the liquid absorption rate is 190%.

[0076] A single-layer dry-process polypropylene diaphragm substrate is selected, with a thickness of 12 μm, a porosity of 39%, and a liquid absorption rate of 36%. Coating 3 has a thickness of 4 μm and coating 4 has a thickness of 4 μm.

[0077] The production steps are as follows:

[0078] a. Substrate surface treatment:

[0079] The coated surface of the polypropylene separator substrate was treated with corona, and the surface tension was 40 dyn / cm.

[0080] b. Coating preparation:

[0081] The composition of slurry B-1 includes: 1 part of silane coupling agent (A187), 19 parts of tetraethyl orthosilicate (TEOS), 30 parts of ethyl acetate, 48.3 parts of ethylene glycol dimeth...

Embodiment 3

[0100] A lithium-ion battery separator is prepared by a single-sided single-layer coating method, and the structure is as follows image 3 As shown, 6 is the coating, 7 is the porous substrate, the total thickness is 25 μm, the porosity is 45%, and the liquid absorption rate is 150%.

[0101] A three-layered separator base film of polypropylene / polyethylene / polypropylene is used, with a thickness of 20 μm, a porosity of 46%, and a liquid absorption rate of 45%.

[0102] The production steps are as follows:

[0103] a. Substrate surface treatment: Flame treatment is carried out on the coated surface of the base film, and the surface tension is 41dyn / cm.

[0104] b. Coating preparation:

[0105] The components of slurry D-1 include: 0.5 parts of silane coupling agent (KH570), 49.5 parts of ethyl acetate, and 50 parts of porous alumina. The average particle diameter of the porous alumina is 5 μm, and the average pore diameter is 8 nm.

[0106] The preparation method of slurry...

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Abstract

The invention discloses a lithium-ion battery diaphragm. The lithium-ion battery diaphragm is prepared by coating the upper surface and the lower surface of a porous base material with one or more porous coatings, wherein the thickness of the porous base material is 4-80 microns; the porosity of the porous base material is 30%-90%; and each porous coating comprises the following raw materials in parts by weight: 30-100 parts of a polymer material, 0-70 parts of inorganic powder and a surface treating agent and 0-50 parts of a compatibilizer. The invention further discloses a preparation method of the lithium-ion battery diaphragm. The battery diaphragm disclosed by the invention is controllable in pore size and porosity and uniform in pore size; the finished diaphragm product is high in high-grade rate, good in wettability and high in safety; and the diaphragm is good in heat resistance, and has a thermal closing function.

Description

technical field [0001] The invention relates to a battery diaphragm, in particular to a lithium ion battery diaphragm and a preparation method thereof. Background technique [0002] The green and pollution-free secondary battery lithium-ion battery is in line with the development direction of energy and environmental protection in various countries today, and its usage in all walks of life is increasing rapidly. As an important part of lithium-ion batteries, the separator plays the role of separating the positive and negative electrodes of the battery cell, and its performance directly affects the overall performance of the battery. [0003] The lithium-ion battery separator is used to isolate the positive and negative electrodes in the battery, allowing free ions to pass between them, preventing the two electrodes from contacting and short-circuiting, and protecting the battery. Therefore, in addition to requiring a certain porosity and pore size distribution for the batte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M2/14H01M50/403H01M50/414H01M50/44H01M50/491
CPCH01M50/403H01M50/411Y02E60/10
Inventor 冯润财郑少华
Owner 郑少华
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