Coating diaphragm for lithium ion battery and preparation method thereof

A lithium-ion battery and coating technology, applied in the field of lithium-ion batteries, can solve the problems of hindering ion conduction and low safety

Active Publication Date: 2017-05-31
SHENZHEN SENIOR TECH MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the water-based PVDF-coated diaphragm will form a film after soaking in the electrolyte, which will hinder the conduction of ions to a certain extent, and the safety is not high.

Method used

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  • Coating diaphragm for lithium ion battery and preparation method thereof

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preparation example Construction

[0022] Correspondingly, the present invention also provides a preparation method of a lithium-ion battery coated separator, comprising the following steps: 5-15 parts by weight of PVDF powder, 2-10 parts by weight of additives, 40-90 parts by weight of the first solvent and 3 ~15 parts by weight of the second solvent are mixed, and mixed slurry is obtained after stirring, and the additive is selected from barium titanate, montmorillonite, carbon nanotubes, polyimide, styrene-butadiene latex, styrene-acrylic latex, polystyrene, One or more of polyacrylonitrile and aramid fiber; the mixed slurry is coated on one or both sides of a polyethylene-based film, pre-solidified, washed with water, and dried to obtain a lithium-ion battery coated separator.

[0023] The additive used in the present invention has the characteristics of high temperature resistance and not being swelled by the electrolyte. Therefore, the addition of the additive can effectively strengthen the skeleton struct...

Embodiment 1

[0031] A kind of lithium-ion battery coating separator and preparation method thereof, the additive that 10 weight parts PVDF powders, 4 weight parts carbon nanotubes and polyimide are formed, wherein the ratio of carbon nanotubes and polyimide is 6: The first solvent that 4,80 parts by weight dimethylacetamide and dimethylformamide are formed, wherein the ratio of dimethylacetamide and dimethylformamide is 5:5, 6 parts by weight of ethanol as the second solvent, The mixed slurry is made under the force of high-speed stirring, coated on both sides of the polyethylene diaphragm, and pre-coagulated in an environment with a relative humidity of 92%. The pre-coagulation time is 5s, the washing time is 10s, and it is dried at 45°C. , the thickness of the single-side coating of the obtained separator was 6 μm.

[0032] Scanning electron microscope analysis is carried out to the separator prepared in this embodiment, the result is as follows figure 1 shown.

Embodiment 2

[0034] A lithium-ion battery coated diaphragm and a preparation method thereof, an additive composed of 8 parts by weight of PVDF powder, 2.5 parts by weight of styrene-butadiene rubber and barium titanate, wherein the ratio of styrene-butadiene rubber and barium titanate is 4:6, 86 parts by weight of N-methylpyrrolidone and the first solvent of trimethyl phosphate, wherein the ratio of N-methylpyrrolidone and trimethyl phosphate is 7:3, the second solvent of 3.5 parts by weight of water and ethyl acetate, wherein The ratio of water and ethyl acetate is 8:2, and the mixed slurry is made under high-speed stirring force, coated on both sides of the polyethylene diaphragm, and pre-coagulated in an environment with a relative humidity of 95%. The pre-coagulation time 4s, washing time 25s, drying at 55°C, and the coating thickness on one side of the obtained separator is 4μm.

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Abstract

The invention provides a preparation method for a coating diaphragm for a lithium ion battery. The method comprises the following steps: mixing PVDF powder, an additive, a first solvent and a second solvent and then stirring, thereby obtaining a mixed sizing agent; coating the mixed sizing agent on one side or two sides of a polyvinyl membrane; and pre-solidifying, washing with water and drying, thereby obtaining the coating diaphragm for the lithium ion battery. The diaphragm prepared according to the invention has excellent adhesiveness; the hardness of the battery is increased; the adopted additive has the characteristics of high temperature resistance and incapability of being dissolved and swelled by electrolyte; the skeleton structure of the coating is effectively enhanced; the membrane breaking temperature of the polyvinyl membrane is increased; and when the temperature in the battery is increased, the coating still can achieve the function of isolating an anode from a cathode. The hole closing/membrane breaking temperature difference of the coating diaphragm prepared according to the invention can reach above 35 DEG C; the safety performance of the battery is greatly promoted; due to the rigid enhancing function of the additive, the curling phenomenon of the coating in a drying process can be avoided; and the preparation method is simple in preparation process, low in cost, safe and controllable.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion battery coated diaphragm and a preparation method thereof. Background technique [0002] Due to its high energy density, high operating voltage, long cycle life and low self-discharge rate, lithium-ion batteries have attracted more and more attention, and their application range has gradually expanded. In the lithium battery structure, the separator is one of the key inner components, which isolates the positive and negative electrodes, prevents the short circuit caused by contact between the two electrodes, and also has the function of providing electrolyte ions to pass through. [0003] With the development of power vehicles, energy density has become the biggest challenge for the current development of lithium-ion batteries. People expect the energy density of batteries to reach a new level, so that the battery life or mileage of the product will no...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M2/14H01M10/42
CPCH01M10/4235H01M2200/00H01M50/403H01M50/411Y02E60/10
Inventor 廖柳辉曹江苗发成朱继俊陈勇陈秀峰
Owner SHENZHEN SENIOR TECH MATERIAL
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