High-strength three-layer co-extrusion lithium ion battery diaphragm and preparation method thereof

A lithium-ion battery, three-layer co-extrusion technology, applied in the direction of secondary batteries, battery pack components, circuits, etc., to achieve the effect of enhancing puncture strength, optimizing porosity and pore size distribution, and avoiding delamination

Active Publication Date: 2022-05-13
NINGBO CHANGYANG TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to overcome the difference in the melt index between the polypropylene materials of each layer when the dry-process diaphragm is prepared by three-layer co-extrusion in the prior art, so as to ensure the processing performance of the diaphragm, but this is not conducive to the pore size of the diaphragm. To improve the distribution and mechanical properties, a high-strength three-layer co-extruded lithium-ion battery separator and its preparation method are provided. Two different polypropylenes with a large difference in melt index are used to make A / The diaphragm with B / A structure, by adding lubricating nucleation particles in the middle layer, can effectively improve the mechanical properties of the diaphragm while ensuring the processing performance of the diaphragm

Method used

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  • High-strength three-layer co-extrusion lithium ion battery diaphragm and preparation method thereof

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preparation example Construction

[0033] In parts by weight, the components of the B layer include 90-99 parts of homopolypropylene and 1-10 parts of lubricating nucleating particles, and the melt index of the homopolypropylene at 230°C is 1-5g / 10min , the isotacticity is not less than 98%; the preparation method of the lubricated nucleating particles comprises the following steps: A) mixing polytetrafluoroethylene micropowder and pimelic acid for ball milling; the ball milling medium is ethanol, and the ball milling time is 1~3h ; B) adding calcium stearate, and continuing ball milling for 0.5~1h; after ball milling, the obtained product was washed and dried to obtain the lubricated nucleation particles; wherein, the added polytetrafluoroethylene micropowder, pimelic acid and stearic acid The mass ratio of calcium is 5~10:1:1~2; the ball milling temperature in steps A) and B) is -20~-10°C, the mass ratio of the balls added during ball milling is 1:10~30, poly The mass volume ratio of fluoroethylene micropowder ...

Embodiment 1

[0043] A high-strength three-layer co-extruded lithium-ion battery separator, including a B layer and an A layer arranged on both sides of the B layer; the total thickness of the separator is 16 μm, wherein the thickness of the B layer is 14 μm, and the thickness of the A layer is 1 μm;

[0044] The component of layer A is copolymerized polypropylene (Korea Petrochemical CB5230, its melt index at 230°C is 30 g / 10min, and its rigid modulus is 18000 kgf / cm 2 , heat distortion temperature is 135 ℃); in parts by weight, the components of layer B include 90 parts of homopolypropylene (Korea Petrochemical S801, whose melt index at 230 ℃ is 3.0 g / 10min, isotactic degree of 98%) and 5 parts of lubricating nucleating particles;

[0045] Among them, the preparation method of lubricating nucleating particles includes the following steps: A) mixing polytetrafluoroethylene micropowder (DuPont MP1300 in the United States) and pimelic acid in a high-energy ball mill for ball milling; the bal...

Embodiment 2

[0055] The difference between Example 2 and Example 1 is: in parts by weight, the components of layer A include 99 parts of copolymerized polypropylene (Korean Petrochemical CB5230) and 1 part of calcium sulfate whisker (Video Bio), and the rest are Same as in Example 1.

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Abstract

The invention relates to the technical field of lithium ion battery diaphragms, and discloses a high-strength three-layer co-extrusion lithium ion battery diaphragm and a preparation method thereof.The diaphragm comprises a layer B and layers A arranged on the two sides of the layer B; the component of the layer A comprises co-polypropylene, and the melt index of the co-polypropylene at 230 DEG C is greater than or equal to 30 g/10 min; the layer B is prepared from the following components in parts by weight: 90 to 99 parts of homo-polypropylene and 1 to 10 parts of lubricating nucleating particles, and the melt index of the homo-polypropylene at 230 DEG C is 1 to 5g/10min; the lubricating nucleation particles are prepared from polytetrafluoroethylene micro powder, pimelic acid and calcium stearate through step-by-step ball milling. According to the invention, the diaphragm with an A/B/A structure is prepared from two different types of polypropylene with relatively large melt index difference in a three-layer co-extrusion manner, and the lubricating nucleation particles are added into the middle layer, so that the mechanical property of the diaphragm is effectively improved while the processing property of the diaphragm is ensured.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery diaphragms, in particular to a high-strength three-layer co-extruded lithium-ion battery diaphragm and a preparation method thereof. Background technique [0002] As the main component of liquid lithium-ion batteries, the battery separator plays a vital role in the battery. The diaphragm material is between the positive and negative electrodes of the lithium battery, a layer of insulating film containing a large number of microporous structures, and the main composition is an insulating polymer material. The main function of the separator is two points: one is to isolate the positive and negative poles in the battery, to prevent the two poles from directly contacting and short circuiting, and at the same time, it needs to be as thin as possible under the premise of ensuring safety, so as to reduce the distance between the two poles and reduce the internal resistance of the battery; the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/414H01M50/457H01M50/403H01M50/489H01M50/491H01M50/494H01M10/0525
CPCH01M50/414H01M50/457H01M50/403H01M50/489H01M50/491H01M50/494H01M10/0525
Inventor 王绪田慧婷范建国李健权杨雄
Owner NINGBO CHANGYANG TECH
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