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Special diaphragm for lithium ion batteries and preparation method of special diaphragm for lithium ion batteries

A lithium ion battery and separator technology, applied in the field of special separators for lithium ion batteries and their preparation, can solve the problems of no selectivity of ion penetration, poor pore closing effect, increased electrolyte contact area, and reduced corrosion resistance of the separator, etc. Achieve good dimensional stability, good closed cell effect, and small reduction in mechanical strength.

Active Publication Date: 2016-07-13
X FIPER NEW MATERIAL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

China International Patent CN201380016862.7 discloses a method by increasing the content of inorganic particles or polymer particles. Although the air permeability of the diaphragm is improved, the surface of the diaphragm is raised due to the increase of particles, which increases the contact with the electrolyte. The contact area greatly reduces the corrosion resistance of the diaphragm, resulting in a shortened service life of the battery
[0005] Chinese patent CN201410826772.0 discloses the use of aramid chopped fibers and precipitated fibers to prepare battery separators by mixing and papermaking, wherein aramid precipitated fibers are used as a bonding effect, and by using aramid fiber membranes instead of thermoplastic polyolefin resins, polyolefin resins are solved. Olefins have poor temperature resistance and poor chemical stability, but aramid fibers have no selectivity for electrolyte ion penetration, and aramid fibers have no melting point, so the membrane made has no closed-pore effect. When the battery is short-circuited, with temperature rising, causing an explosion
[0006] In order to overcome the problems in the prior art that the laminated heat-resistant layer on the surface of polyolefin causes the diaphragm to be airtight, not corrosion-resistant, and the replacement of the heat-resistant substrate results in no selectivity for ion permeation and poor closed-cell effect, therefore, it is necessary to provide a New special separator for lithium-ion batteries to solve the above problems

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] a) Immerse the diaphragm substrate into the tank filled with the aromatic polyimide solution, take it out after 20 seconds, the diaphragm substrate is a polypropylene porous membrane, and the concentration of the aromatic polyimide solution is 5wt %, the solvent used in the aromatic polyimide solution is dimethylacetamide, and the solute is aromatic polyimide;

[0025] b) immerse the diaphragm base material in the first to third coagulation baths sequentially, each coagulation bath is a mixed solution of dimethylacetamide, lithium chloride and deionized water, the first The concentration of dimethylacetamide and lithium chloride in the third-level coagulation bath decreases successively, and the weight ratio of dimethylacetamide and lithium chloride is 1:2, wherein, in the first-level coagulation bath The weight ratio of dimethylacetamide and deionized water is 5:10, the weight ratio of dimethylacetamide in the second-stage coagulation bath and deionized water is 3:10, ...

Embodiment 2

[0030] a) Immerse the diaphragm substrate into the tank filled with the para-aramid solution, take it out after 50 seconds, the diaphragm substrate is a polyethylene porous film, and the concentration of the para-aramid solution is 30wt %, the solvent used in the para-aramid solution is dimethylacetamide, and the solute is para-aramid;

[0031] b) immerse the diaphragm base material in the first to third coagulation baths sequentially, each coagulation bath is a mixed solution of dimethylacetamide, lithium chloride and deionized water, the first The concentration of dimethylacetamide and lithium chloride in the third-level coagulation bath decreases successively, and the weight ratio of dimethylacetamide and lithium chloride is 2:1, wherein, in the first-level coagulation bath The weight ratio of dimethylacetamide and deionized water is 6:10, the weight ratio of dimethylacetamide in the second-stage coagulation bath and deionized water is 5:10, and the third-stage coagulation ...

Embodiment 3

[0036] a) Immerse the diaphragm substrate into the tank containing the meta-aramid solution, take it out after 30 seconds, the diaphragm substrate is a polyethylene porous film, and the concentration of the meta-aramid solution is 8wt %, the solvent used in the meta-position aromatic polyamide solution is dimethylacetamide, and the solute is meta-position aromatic polyamide;

[0037]b) immerse the diaphragm base material in the first to third coagulation baths sequentially, each coagulation bath is a mixed solution of dimethylacetamide, lithium chloride and deionized water, the first The concentration of dimethylacetamide and lithium chloride in the third-level coagulation bath decreases successively, and the weight ratio of dimethylacetamide and lithium chloride is 1:1, wherein, in the first-level coagulation bath The weight ratio of dimethylacetamide and deionized water is 5.5:10, the weight ratio of dimethylacetamide in the second-stage coagulation bath and deionized water ...

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Abstract

The invention discloses a preparation method of a special diaphragm for lithium ion batteries.The special diaphragm for the lithium ion batteries comprises a substrate layer which is a polyethylene porous membrane or a polypropylene porous membrane, and aromatic polyamide or aromatic polyimide is uniformly attached to the surface of the substrate layer.The special diaphragm for the lithium ion batteries is 0.02-0.045mm in thickness and 50-60% in porosity.Compared with the prior art, the special diaphragm for the lithium ion batteries has the advantages of high resistance to heat and ageing, high porosity and air permeability, low closed pore temperature, small thickness and high breaking temperature.

Description

technical field [0001] The invention relates to a special diaphragm for lithium ion batteries and a preparation method thereof. Background technique [0002] With the rapid development of science and technology and electronic equipment, lithium-ion batteries are widely used. Lithium-ion batteries are composed of traditional aramid paper-based honeycomb materials, electrolytes and separators. The dissociated positive and negative ions freely pass between the positive and negative electrodes, so they play a vital role in the battery and have a direct impact on the safety of the battery. [0003] The diaphragm is generally a porous film made of thermoplastic resin. Although it has electrical insulation, ion permeability, electrolyte corrosion resistance and closed-cell effect, its melting temperature and heat aging resistance are poor. With the development of large-capacity batteries, the limitation of temperature resistance and heat aging resistance of thermoplastic resins po...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M10/0525H01M50/409
CPCH01M10/0525H01M50/403H01M50/409Y02E60/10
Inventor 钟洲何素文丁秀臣杨威
Owner X FIPER NEW MATERIAL CO LTD
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