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Battery isolating membrane, preparation method thereof and secondary battery

A separator and battery technology, applied in battery pack components, non-aqueous electrolyte batteries, circuits, etc., can solve the problems of reduced heat resistance, battery short-circuit, and high battery short-circuit rate, improve liquid absorption and wetting ability, enhance Force and stability, the effect of building a three-dimensional skeleton structure

Pending Publication Date: 2022-04-01
SINOMA LITHIUM BATTERY SEPARATOR CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] At present, most of the substrates of commercial battery separators are made of polyolefin. Because polyolefin itself has a low melting point, the separator will shrink severely when it is above 100°C, causing the positive and negative electrodes to contact, which will easily cause the battery to catch fire and explode.
In order to improve the above problems, one or more layers of functional coatings are usually coated on the surface of polyolefin substrates. Common coatings mainly include inorganic filler coatings, polymer coatings, and inorganic fillers and polymer materials. Hybrid coating, although the traditional inorganic filler coating can maintain a certain shape at high temperature, but the hardness of the inorganic material is high, it is easy to scratch the substrate during the coating process, resulting in a high short circuit rate during the battery assembly process; polymer materials It has a high melting point, but it is applied as a coating on the surface of the substrate, and it is loosely bonded to the substrate, and the heat resistance is reduced, causing a short circuit of the battery and causing a safety accident

Method used

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  • Battery isolating membrane, preparation method thereof and secondary battery
  • Battery isolating membrane, preparation method thereof and secondary battery

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preparation example Construction

[0063] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned battery separator, comprising the following steps:

[0064] (1) Prepare the base material;

[0065] (2) Put the non-conductive particles into the organic solvent, and after the dispersion is even, add the heat-resistant resin to continue the dispersion to obtain the slurry;

[0066] (3) using the slurry prepared in step (2) to coat at least one side of the substrate to obtain a coating film;

[0067] (4) passing the coating film through a coagulation bath or saturated steam, the heat-resistant resin porous coating forms a network fiber structure, and the inorganic particles are evenly distributed in the porous coating;

[0068] (5) washing the coating film obtained in step (4) with water, and drying to obtain a battery separator.

[0069] In step (1), the preparation method of the base material is not particularly limited, dry uniaxial stretching, bidire...

Embodiment 1

[0078] (1) Add 4 parts of alumina powder to 100 parts of NMP, stir through a high-speed dispersing emulsifier for 20 minutes, then add 2 parts of para-aramid, continue stirring for 20 minutes with a high-speed dispersing and emulsifying machine, and obtain a uniform The para-aramid fiber slurry, wherein the alumina particle size D97 = 1.125, particle size distribution α = 2.32, β = 3.852 × 10 7 m / g;

[0079] (2) Choose a polyethylene-based film with a thickness of 9 μm, a porosity of 38%, and an air permeability of 150 s / 100 cc. Use the gravure coating method to first coat one side of the base film with an organic solvent, and then coat it on the other side of the base film. One side is coated with the above-mentioned para-aramid slurry by gravure coating, and the coating thickness is 3.1 μm;

[0080] (3) The prepared coating film stays in a saturated steam atmosphere, then enters a pure water tank for washing, and finally enters an oven for drying to obtain a battery separat...

Embodiment 2

[0082] (1) Add 4 parts of boehmite powder to 100 parts of NMP, stir for 20 minutes through a high-speed dispersing emulsifier, then add 2 parts of para-aramid, continue stirring for 20 minutes with a high-speed dispersing and emulsifying machine, and obtain a uniform mixture after filtering through a 1000-mesh filter. Para-aramid slurry, in which boehmite particle size D97=1.032, particle size distribution α=2.59, β=3.53×10 7 m / g;

[0083] (2) Choose a polyethylene-based film with a thickness of 9 μm, a porosity of 38%, and an air permeability of 150 s / 100 cc. Use the gravure coating method to first coat one side of the base film with an organic solvent, and then coat it on the other side of the base film. One side is coated with the above-mentioned para-aramid slurry by gravure coating, and the coating thickness is 3.0 μm;

[0084] (3) The prepared coating film stays in a saturated steam atmosphere, then enters a pure water tank for washing, and finally enters an oven for dr...

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Abstract

The invention provides a battery isolating membrane, a preparation method thereof and a secondary battery, and relates to the technical field of batteries, the isolating membrane comprises a base material with a porous structure and a heat-resistant polymer coating coated on at least one surface of the base material; the heat-resistant polymer coating comprises heat-resistant resin and non-conductive particles; the particle size D97 of the non-conductive particles is less than or equal to the thickness of the heat-resistant polymer coating; the particle size distribution of the non-conductive particles meets the condition that 0.5 < = (D90-D10) / D50 < = 3.0; the ratio of the specific surface area S of the non-conductive particles to the average particle size D50 is 0 lt; s / D50 < = 5 * 107 m / g. The diaphragm disclosed by the invention has a uniform porous coating, relatively high temperature resistance and excellent electrochemical stability, and the assembly yield, the electrical property and the safety performance of the battery are greatly improved.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a battery separator, a preparation method thereof, and a secondary battery. Background technique [0002] With the development of new energy technology, secondary batteries are applied to digital products, electric vehicles and energy storage devices due to their high energy density, long life and high safety performance. The secondary battery is mainly composed of four parts, namely the positive electrode, the electrolyte, the separator, and the negative electrode. Among them, the main function of the separator is to separate the positive and negative electrodes and prevent the direct contact between the positive and negative electrodes to cause a short circuit. In addition, the through-hole structure in the separator can play the role of allowing the positive and negative ions to pass through. The performance of the separator It will directly affect important performances su...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/403H01M50/414H01M10/05
CPCY02E60/10H01M50/414H01M50/403H01M10/05
Inventor 白麟王连广刘淑真高飞飞汤晓秦文娟张绪杰刘杲珺白耀宗甘珊珊
Owner SINOMA LITHIUM BATTERY SEPARATOR CO LTD