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Modified composite diaphragm and method for preparing diaphragm

A composite modification and diaphragm technology, applied in chemical instruments and methods, synthetic resin layered products, electrical components, etc., can solve the problems of unfavorable high-rate discharge performance of batteries, high air permeability of diaphragms, and high preparation costs, and achieve easy The effect of industrialized production, low air permeability value and low preparation cost

Inactive Publication Date: 2015-05-20
SHENZHEN WISEWOD TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Using this diaphragm can indeed greatly improve its thermal stability, but it still needs to use organic solvents to form sol-like polymers, such as dimethylformamide, triethyl phosphate, N-methylpyrrolidone, dimethyl Based on sulfoxide, the organic solvent is toxic, not conducive to environmental protection and the preparation cost is high. In addition, the gas permeability of the prepared separator is relatively high, which is not conducive to the high rate discharge performance of the battery.

Method used

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  • Modified composite diaphragm and method for preparing diaphragm
  • Modified composite diaphragm and method for preparing diaphragm
  • Modified composite diaphragm and method for preparing diaphragm

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preparation example Construction

[0031] Specifically, the preparation method of the composite modified diaphragm according to the embodiment of the present invention includes the following steps:

[0032] A), the thickener is dissolved in deionized water to form an aqueous solution;

[0033] B), ceramics and polyvinylidene fluoride-hexafluoropropylene are dispersed in an aqueous solution to form a suspension;

[0034] C) A binder is added to the suspension to form a slurry. In the slurry, deionized water accounts for 50-80 wt%, ceramics accounts for 20-60 wt%, and polyvinylidene fluoride-hexafluoropropylene accounts for 20-60 wt%. , the binder accounts for 1.5-8wt%, and the thickener accounts for 0.3-0.8wt%;

[0035] D), the slurry is evenly coated on at least one surface of the film substrate;

[0036] E), drying the film substrate coated with the slurry to obtain a composite modified diaphragm;

[0037] Wherein, the ceramic is selected from one or more of alumina, zirconia and titania with a particle dia...

specific Embodiment 1

[0045] Get polyethylene microporous membrane as base material, its thickness is 9 μm, 0.3g thickening agent sodium carboxymethyl cellulose (molecular weight is about 6.0×10 4 ) was dispersed in 105 g of deionized water and stirred at a controlled speed of 1500 r / min, and stirred for 0.5 h. Then 75g of alumina (particle size D50 is 200nm) and 25g of polyvinylidene fluoride-hexafluoropropylene (molecular weight is 200,000, average particle size is 10 μm) are added step by step into the solution and stirred at high speed, the control speed is 2500r / min, Stir for 2h. Then add 10 g of the binder polyacrylate emulsion into the suspension, control the stirring speed to 2500 r / min, and stir for 1 hour to obtain the slurry. The slurry is evenly coated on one side of the substrate, and the wet film thickness on one side is controlled to be 10-20 μm. Then place the wet coating at 38~50℃ to blow dry, control the air volume to 30m 3 / h, and the drying time was controlled for 5-10 minute...

specific Embodiment 2

[0046] Get polyethylene microporous membrane as base material, its thickness is 9 μm, 0.3g thickening agent sodium carboxymethyl cellulose (molecular weight is about 6.0×10 4 ) was dispersed in 105 g of deionized water and stirred at a controlled speed of 1500 r / min, and stirred for 0.5 h. Then 70g of alumina (particle size D50 is 800nm) and 30g of polyvinylidene fluoride-hexafluoropropylene (molecular weight is 2 million, average particle size is 8 μ m) are added to the solution step by step and stirred at high speed, the control speed is 2500r / min, Stir for 2h. Then add 10 g of the binder polyacrylate emulsion into the suspension, control the stirring speed to 2500 r / min, and stir for 1 h. That is, the slurry is obtained. The slurry is evenly coated on one side of the substrate, and the wet film thickness on one side is controlled to be 10-20 μm. Then place the wet coating at 38~50℃ to blow dry, control the air volume to 30m 3 / h, and the drying time was controlled for 5...

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Abstract

The invention relates to a modified composite diaphragm and a method for preparing the diaphragm. The preparation method is characterized in that ceramics and polyvinylidene fluoride-hexafluoropropylene with proper particle sizes are selected and the ratio of contents in a slurry is controlled, so that ceramics and polyvinylidene fluoride-hexafluoropropylene can be uniformly dispersed in an aqueous solution to form the easily coated slurry with proper viscosity and steadiness under the action of a binder and a thicker; the modified composite diaphragm with better permeability and lower air permeability values can be prepared after the easily coated slurry coats the surface of a film substrate, and the whole preparation process is an aqueous preparation process without including organic solvents and forming sol-like polymers, thus the modified composite diaphragm is simple in preparation method, low in cost, environmentally friendly and easy in realizing industrial production.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a composite modified diaphragm and a preparation method thereof. Background technique [0002] The battery separator refers to the polymer separator between the positive and negative electrodes of the lithium-ion battery. It is one of the most critical parts of the lithium-ion battery and has a direct impact on battery safety. Its functions are: to isolate the positive and negative electrodes and prevent the electrons in the battery from passing freely; to enable the ions in the electrolyte to pass freely between the positive and negative electrodes. [0003] At present, in commonly used lithium-ion batteries, the separator and the positive and negative electrodes are only weakly bonded by the weak surface tension generated by the separator. Problems such as uneven spacing lead to uneven current density during use of the battery, increased electrode polarization, a...

Claims

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Application Information

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IPC IPC(8): H01M2/16B32B27/32H01M50/426H01M50/491
CPCB32B27/32B32B27/322H01M50/446H01M50/403Y02E60/10
Inventor 商光禄李斌朱继涛
Owner SHENZHEN WISEWOD TECH
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