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Composite diaphragm for lithium ion batteries, production method thereof, and lithium ion battery

A lithium-ion battery, composite diaphragm technology, applied in secondary batteries, battery pack parts, separators/films/diaphragms/spacers, etc. Problems such as direct contact between positive and negative electrodes

Inactive Publication Date: 2017-12-05
WINNERWAY MOTORS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The polymer separator is light in weight and has good electronic insulation performance. The disadvantage is that the melting point of the polymer is generally low. When the battery is thermally abused, the heat accumulation inside the battery is easy to deform and the positive and negative electrodes are in direct contact with each other. short circuit
In order to improve the safety of the separator, many inorganic fillers have been coated on the surface of the polyolefin separator in recent years to improve the thermal stability of the separator. However, when the battery works for a long time, a short circuit will still occur, and the ceramic coating separator will It also reduces the wettability of the diaphragm and the electrolyte; in addition, the inorganic filler powder without surface treatment is prone to agglomeration and falls off from the surface of the polyolefin diaphragm, affecting the performance of the diaphragm product

Method used

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  • Composite diaphragm for lithium ion batteries, production method thereof, and lithium ion battery
  • Composite diaphragm for lithium ion batteries, production method thereof, and lithium ion battery

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preparation example Construction

[0030] The present invention also provides a preparation method of a composite diaphragm for a lithium ion battery, comprising the following steps:

[0031] A. Carry out swelling treatment to cellulose, obtain swollen cellulose;

[0032] B. Mix the ceramic particles and ceramic whiskers in the dispersant evenly, then add swelling cellulose, add the binder after mixing evenly, and obtain the ceramic slurry after stirring evenly;

[0033] C. Coating the ceramic slurry on the surface of the polymer matrix, and drying to obtain a composite thin film for the lithium ion battery.

[0034] According to the present invention, the ceramic slurry is coated on the surface of the polymer matrix by a coating method, the coating speed is 5-100m / min, the drying temperature is 30-80°C, and the ceramic slurry coats the base film The thickness of the obtained ceramic coating is 0.1-50 μm.

[0035]According to the present invention, in step A, the swelling treatment step of the cellulose is: s...

Embodiment 1

[0044] A lithium ion battery is made up of positive pole, negative pole and diaphragm, and its preparation method is as follows:

[0045] (1) Preparation of positive electrode

[0046] 100 parts by weight of the positive electrode active material LiNi 0.33 co 0.33 mn 0.34 o 2 , 4 parts by weight of binder polyvinylidene fluoride (PVDF), 4 parts by weight of conductive agent acetylene black are added in 50 parts by weight of N-methylpyrrolidone (NMP), then stirred in a vacuum mixer to form a uniform positive electrode slurry ; Coat the slurry evenly on an aluminum foil with a width of 400mm and a thickness of 20μm, then dry it at 120°C, roll it under a pressure of 1.6MPa and cut it on a slitting machine to obtain a positive electrode with a size of 385mm×42mm×135μm , the dressing density of the obtained positive electrode sheet is 3.4g / cm 3 .

[0047] (2) Preparation of negative electrode

[0048] 100 parts by weight of negative electrode active material natural graphite...

Embodiment 2

[0056] A lithium ion battery is made up of positive pole, negative pole and diaphragm, and its preparation method is as follows:

[0057] (1) The preparation method of positive electrode is the same as embodiment 1;

[0058] (2) the preparation method of negative pole is with embodiment 1;

[0059] (3) Preparation of diaphragm:

[0060] A. Soak 1.5 parts by weight of cellulose in sodium hydroxide / urea aqueous solution (25° C.) for 5 hours, then filter to remove the filtrate, wash the filter residue with water until neutral, then ultrasonically disperse for 30 minutes, and filter to obtain swollen cellulose;

[0061] B, 9 parts by weight of magnesium oxide particles (average particle diameter is 10nm), 20 parts by weight of titanium dioxide particles (average particle diameter is 50nm), polyurethane spinning 0.72 parts by weight (average diameter is 100nm) and yttrium oxide crystal 5.8 parts by weight of whiskers (the average diameter is 100nm, and the average length is 2 μm)...

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Abstract

The invention relates to the technical field of lithium ion batteries, and discloses a composite diaphragm for lithium ion batteries, a production method thereof, and a lithium ion battery. The composite diaphragm for lithium ion batteries includes a polymer matrix and a ceramic film coated on the surface of the polymer matrix, the ceramic film is made of a ceramic slurry, the ceramic slurry contains a dispersant, a binder and a powder, and the powder contains ceramic particles, ceramic whiskers and cellulose. The addition of ceramic fibers to the ceramic slurry increases the mechanical properties of the composite film, so the composite film does not shed from the polymer matrix, maintains a good adhesion, and inhibits dry linting of the ceramic diaphragm; and the addition of the cellulose increases the electrolyte absorption and retention ability of the diaphragm, and also effectively reduces the thermal shrinkage rate of the diaphragm at a high temperature.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a composite separator for lithium ion batteries, a preparation method thereof and a lithium ion battery. Background technique [0002] In recent years, with the depletion of earth resources and the enhancement of social environmental awareness, green and clean energy has become an important direction in the field of energy storage and energy conversion. As a basic energy storage and conversion device, chemical power sources have become an indispensable part of production and life. Today, with the rapid development of portable electronic devices, the demand for rechargeable chemical power sources is extremely urgent. Compared with traditional secondary batteries such as nickel-cadmium and lead-acid, lithium-ion batteries have the characteristics of high energy density, long life and no pollution to the environment, and have been widely used as power sources for port...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M2/16H01M10/0525H01M50/403H01M50/426H01M50/434
CPCH01M10/0525H01M50/409H01M50/403Y02E60/10
Inventor 刘营涛徐清孙步云陈辉智吴宏义
Owner WINNERWAY MOTORS CO LTD
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