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Compound lithium-ion battery diaphragm and preparation method thereof

A technology for ion batteries and lithium composites, which is applied to battery components, separators/films/diaphragms/spacers, circuits, etc., and can solve the problems of inability to meet the requirements of high-rate charge and discharge, increased curvature of the internal aperture of the diaphragm, and Increase the ion transfer path and other issues to achieve the effects of avoiding interface defects, improving electrochemical performance, and increasing liquid absorption rate

Active Publication Date: 2015-02-18
SUZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] However, the blended separator increases the bending degree of the internal pore diameter of the prepared separator, which increases the ion transfer path, which is not conducive to the improvement of its electrochemical performance. The current blending modification method can no longer meet the requirements of high rate charge and discharge.

Method used

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  • Compound lithium-ion battery diaphragm and preparation method thereof
  • Compound lithium-ion battery diaphragm and preparation method thereof
  • Compound lithium-ion battery diaphragm and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] 1. Preparation of PVDF-HFP composite diaphragm supported by PP non-woven fabric (slurry solid content 10%):

[0038] (1) Treatment of PP non-woven fabrics: arrange PP non-woven fabrics in ethanol, ultrasonically clean them for 30 minutes, dry them and place them in an oven at 70 °C for flattening treatment;

[0039] (2) Preparation of PVDF-HFP composite diaphragm supported by PP non-woven fabric: Weigh 5 g polyvinylidene fluoride hexafluoropropylene (PVDF-HFP), dissolve it in 45 g acetone and 5 g DMF, stir and dissolve for 2 hours, It was then coated on a flat polypropylene non-woven fabric, dried naturally for 30 minutes, and then vacuum-dried at 60°C for 8 hours to obtain a PVDF-HFP composite separator supported by PP non-woven fabric.

[0040] 2. Half-battery test results: The theoretical specific capacity of the lithium-ion half-battery is 170 mA·h·g -1 , the actual discharge specific capacity at 0.2 C / 0.2 C is 143 mA·h·g -1 , the coulombic efficiency of the batte...

Embodiment 2

[0042] 1. Preparation of three-layer composite separator for lithium ion battery:

[0043] (1) PMMA nanoparticles were obtained by soap-free emulsion polymerization, with an average particle size of 200 nm; the emulsion obtained by polymerization was concentrated to a solid content of 10% by a rotary evaporator;

[0044] (2) Treatment of PP non-woven fabric: arrange PP non-woven fabric in ethanol, ultrasonically clean it for 30 minutes, dry it and place it in an oven at 70 °C for flattening treatment;

[0045] (3) The intermediate matrix layer is obtained by solution coating, and the large-pore diameter PP non-woven fabric is used as the support material. The preparation process is as follows: weigh 5 g of PVDF-HFP, dissolve in 45 g of acetone and 5 g of DMF, and stir to dissolve 2 hours, then coated on a flat polypropylene non-woven fabric, dried naturally for 30 minutes, and then vacuum-dried at 60°C for 8 hours to obtain a PVDF-HFP matrix film supported by a PP non-woven fa...

Embodiment 3

[0057] A three-layer composite separator for lithium-ion batteries was prepared as follows:

[0058] (1) PMMA nanoparticles were obtained by soap-free emulsion polymerization, 100 nm; the emulsion obtained by polymerization was concentrated to a solid content of 20% by a rotary evaporator;

[0059] (2) Treatment of PP non-woven fabrics: arrange PP non-woven fabrics in ethanol, ultrasonically clean them for 30 min, dry them and place them in an oven at 70 °C for flattening treatment;

[0060](3) The intermediate matrix layer was obtained by solution coating, and the above-mentioned PP non-woven fabric was used as the supporting material. The preparation process is as follows: weigh 5 g PVDF-HFP, dissolve in 45 g acetone and 5 g DMF, stir and dissolve for 2 hours, and then apply it on a flat PP non-woven fabric, let it dry naturally for 30 minutes, and then dry it at 60 Vacuum drying at ℃ for 8 hours to obtain a PVDF-HFP matrix layer supported by PP non-woven fabric;

[0061] ...

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Abstract

The invention relates to a compound lithium-ion battery diaphragm and a preparation method thereof, aiming to solve the problems of low ionic conductivity, poor rate discharge performance, poor heat resistance stability and the like of an existing battery diaphragm. The compound lithium-ion battery diaphragm has a sandwich type lamellar structure, the middle of the compound lithium-ion battery diaphragm is a PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) matrix layer supported by a PP (Propene Polymer) nonwoven fabric, and two sides of the compound lithium-ion battery diaphragm are nanometer layers uniformly covered by polymer nanoparticles. The compound lithium-ion battery diaphragm has a porosity of reaching 75 percent, a liquid absorbing rate of being greater than 200 percent, and an ionic conductivity of about 1.846-10<-3> S / cm. A LiFePO4 / CPE / Li battery is assembled by using the compound lithium-ion battery diaphragm, the discharge specific capacity at 0.2C / 0.2C reaches 150 mA.h.g<-1> (theoretical specific capacity is 170 mA.h.g<-1>), the coulombic efficiency of a battery reaches 99 percent; and the discharge at 2C / 0.2C can be always kept 90 percent of the original specific capacity.

Description

technical field [0001] The invention relates to the technical field of lithium-ion battery diaphragm production, in particular to a modified composite diaphragm for lithium-ion batteries and a preparation method thereof. Background technique [0002] Lithium-ion batteries, as one of the important modern energy storage devices, have attracted extensive attention of researchers. Lithium-ion batteries have the advantages of high energy density and high stability, and are widely used in mobile electronic devices and electric vehicles. In addition, its application in electric vehicles has the advantage of zero carbon emissions, making the modern automobile industry extremely demanding the development of lithium-ion batteries with fast charging and discharging performance. The discharge rate of the battery refers to the current value required by the battery to discharge its rated capacity within a specified time, which is numerically equal to the multiple of the rated capacity of...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M50/403H01M50/417H01M50/42H01M50/426H01M50/443H01M50/457H01M50/489H01M50/491H01M50/497
CPCH01M50/409H01M50/403Y02E60/10
Inventor 张明祖吴大钊何金林倪沛红
Owner SUZHOU UNIV
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