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A kind of composite 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 transmission path and other issues to achieve the effects of avoiding interface defects, improving electrochemical performance, and increasing liquid absorption rate

Active Publication Date: 2017-03-22
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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  • A kind of composite lithium-ion battery diaphragm and preparation method thereof
  • A kind of composite lithium-ion battery diaphragm and preparation method thereof
  • A kind of composite 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 (solid content of slurry 10%):

[0038] (1) PP non-woven fabric treatment: arrange the PP non-woven fabric in ethanol, ultrasonically clean for 30 minutes, dry it and place it in an oven at 70 ℃ 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, Then, it was 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 membrane supported by the PP non-woven fabric.

[0040] 2. Half-cell test result: The theoretical specific capacity of the lithium-ion half-cell is 170 mA·h·g -1 ,The actual discharge specific capacity at 0.2 C / 0.2C is 143 mA·h·g -1 , The coulombic efficiency of the battery reaches over 85%;...

Embodiment 2

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

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

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

[0045] (3) The intermediate base layer is obtained by solution coating, and the large pore size PP non-woven fabric is used as the support material. The preparation process is: weigh 5 g PVDF-HFP, dissolve it in 45 g acetone and 5 g DMF, stir and dissolve 2 hours, then coated on a flat polypropylene non-woven fabric, air-dried for 30 minutes, and then vacuum dried at 60 ℃ for 8 hours to obtain a PVDF-HFP base film supported by PP non-woven fabric, which is the middle layer;

[0046] (4) Im...

Embodiment 3

[0057] The three-layer composite diaphragm of lithium ion battery is prepared as follows:

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

[0059] (2) PP non-woven fabric treatment: arrange the PP non-woven fabric in ethanol, ultrasonically clean for 30 min, dry it and place it in an oven at 70 ℃ for flattening treatment;

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

[0061] (4) Immerse the obtained substrate layer in P...

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Abstract

The invention relates to a composite lithium ion battery diaphragm and a preparation method thereof. The purpose of the invention is to solve the problems of low ion conductivity, poor rate discharge performance and poor heat resistance stability of the existing battery separator. The composite separator has a sandwich-type layered structure: a PVDF-HFP matrix layer supported by PP non-woven fabric in the middle, and nano-layers uniformly covered by polymer nanoparticles on both sides. The composite membrane has a porosity of 75%, a liquid absorption rate of more than 200%, and an ion conductivity of about 1.846×10-3 S / cm. The composite separator was assembled into a LiFePO4 / CPE / Li battery, and the discharge specific capacity at 0.2 C / 0.2 C reached 150 mA·h·g-1 (theoretical specific capacity was 170 mA·h·g-1). Coulombic efficiency reaches 99%; discharge at 2 C / 0.2 C can still maintain 90% 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] As one of modern important energy storage devices, lithium-ion batteries have attracted extensive attention from 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, which makes the modern automobile industry extremely need to develop lithium-ion batteries with fast charge and discharge performance. The discharge rate of a battery refers to the current value required when the battery discharges its rated capacity within a specified time, and it is numerically equal to a multiple of the battery's rated capacity. How to improv...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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