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Thermal shutdown composite diaphragm and application thereof

A composite diaphragm and thermal shutdown technology, applied in the field of electrochemistry, can solve the problems of non-woven substrates without thermal shutdown function, explosion, and inability to effectively prevent the development of battery reactions, etc.

Inactive Publication Date: 2015-05-06
XIAMEN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] 1. Due to the limitation of the manufacturing process, the non-woven fabric substrate usually has a pore size of more than 1-2 μm. The huge pore size will lead to uneven internal current of the lithium battery, which will further lead to the generation of lithium branch crystals and cause the loss of lithium battery capacity.
[0006] 2. Although the non-woven fabric substrate can improve the thermal stability of the separator itself by means of material selection and other means, the non-woven fabric substrate itself does not have a thermal shutdown function. When the lithium battery thermal runaway occurs, it cannot effectively prevent the battery from reacting. Further development, the temperature continues to rise, causing the battery to burn or explode
However, none of the diaphragms in the prior art has a temperature-controlled thermal shutdown function and a suitable pore size at the same time.

Method used

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  • Thermal shutdown composite diaphragm and application thereof
  • Thermal shutdown composite diaphragm and application thereof
  • Thermal shutdown composite diaphragm and application thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0054]Mix 1g of spray-dried and granulated PE balls (PE molecular weight 10000-20000) with sodium carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) at a mass ratio of 95:2:3, and put it into deionized water Mix 10ml of the solution with acetone (3:1, v:v), ball mill the obtained slurry overnight, ultrasonically disperse the mixed slurry for 20 minutes, and apply the obtained slurry to membrane coating. The thermal shutdown composite diaphragm was fabricated with PI nonwoven fabric as the thermal support layer. The resulting slurry was evenly coated on one side of the PI non-woven membrane, and the thickness of the coating layer was controlled at 3 μm. Use an electric heating plate to preheat at 60°C, wait for most of the solvent to volatilize, put it in a vacuum oven and dry it overnight at 60°C to completely remove the solvent, and obtain a non-woven composite diaphragm with a thermal shutdown temperature from 115°C to >200°C (scan Electron microscope photos su...

Embodiment 2

[0059] Mix 10g of spray-dried and granulated PP balls (PP molecular weight 100,000-200,000) with sodium carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) in a mass ratio of 90:4:6, and put them into deionized water Mix 150ml of the solution with acetone (4:1, v:v), ball mill the obtained coating slurry overnight, and ultrasonically disperse the mixed slurry for 20 minutes, and apply the obtained slurry to membrane coating. The composite diaphragm was fabricated with PMIA electrospun microporous membrane as thermal support layer. The obtained slurry is evenly coated on both sides of the PMIA electrospun microporous membrane, and the thickness of the coating layer is controlled at 5 μm. Preheat with an electric heating plate at 80°C, wait for most of the solvent to volatilize, put it in a vacuum oven at 80°C and dry overnight to completely remove the solvent, and obtain a composite diaphragm with a thermal shutdown temperature from 155°C to >200°C. The resulting d...

Embodiment 3

[0062] Mix 100g of spray-dried and granulated PE balls (PE molecular weight 1,000,000-2,000,000) with gelatin and polyvinyl alcohol (PVA) in a mass ratio of 80:8:12, and put them into deionized water and ethanol (4:1, v: v) Mix 1 L of solution, ball mill the obtained ceramic slurry overnight, ultrasonically disperse the mixed slurry for 50 minutes, and apply the obtained slurry to membrane coating. The thermal shutdown composite diaphragm was fabricated with PET non-woven fabric as the thermal support layer. The obtained slurry was evenly coated on one side of the PET non-woven membrane, and the thickness of the coating layer was controlled at 1 μm. Preheat with an electric heating plate at 70°C, wait for most of the solvent to volatilize, put it in a vacuum oven at 70°C and dry overnight to completely remove the solvent, and obtain a non-woven composite diaphragm with a thermal shutdown temperature from 115°C to >180°C. The resulting diaphragm was clamped between two metal s...

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Abstract

The invention discloses a thermal shutdown composite diaphragm and an application thereof. The thermal shutdown composite diaphragm consists of a nonwoven fabric base material with a melting point of 150 to 350 DEG C and a coating which is smeared on the surface of the nonwoven fabric base material, wherein the thickness of the coating is 0.5 to 20 micrometers, raw materials of the coating include a polymer, a binder and a solvent, the melting point of the polymer is 80 to 170 DEG C, the mass ratio of the polymer to the binder is (80-95): (5-20), and the binder accounts for 0.1 to 20 percent of the total mass of the polymer, the binder and the solvent. A lithium ion battery utilizing the thermal shutdown composite diaphragm has the characteristics of high capacity, good circulating property, good multiplying power performance and the like, a thermal shutdown function is given to the nonwoven fabric base material, and the aperture of the nonwoven fabric base material is effectively reduced.

Description

technical field [0001] The invention belongs to the technical field of electrochemistry, and in particular relates to a heat-shutdown composite diaphragm and an application thereof. Background technique [0002] At present, chemical power systems using liquid electrolytes, such as lithium-ion batteries, need to use diaphragm materials to block the positive and negative electrodes to avoid short circuits. The diaphragm material is mainly composed of polyethylene (Polyethylene, PE), polypropylene (Polypropylene, PP), polytetrafluoroethylene (Polytetrafluoroethylene, PTFE) and other polymer films containing microporous structures, non-woven fabrics and electrospun fabrics. Silk septum. Liquid electrolyte (generally a carbonate organic solvent containing electrolyte salt) exists in the microporous structure to realize the conduction of ions between the positive and negative electrodes. The separator and liquid electrolyte constitute the electrolyte system. [0003] With the d...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M10/0525H01M50/414H01M50/449
CPCY02E60/10
Inventor 赵金保张鹏石川
Owner XIAMEN UNIV
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