Composite separator, fabrication method thereof and lithium ion battery

A composite diaphragm and electrical insulation technology, applied in secondary batteries, battery pack components, circuits, etc., can solve problems such as explosion, battery positive and negative short circuit, and potential safety hazards

Active Publication Date: 2017-06-20
TSINGHUA UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

During the cycle, the lithium dendrites that continue to grow on the negative electrode will pierce the separator and reach the positive electrode, causing a short circuit between the positive and negative electrodes inside the battery, causing local overheating and causing fire or even explosion, which poses a great safety hazard.

Method used

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  • Composite separator, fabrication method thereof and lithium ion battery

Examples

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preparation example Construction

[0045] The present invention also provides a preparation method of the composite diaphragm 10, comprising:

[0046] S110, prepare the conductive fiber layer 12; and

[0047] S120 , forming an electrically insulating nanofiber layer 14 on the conductive fiber layer 12 .

[0048] Preferably, further comprising:

[0049] S130 , forming an inorganic nanolayer 16 on the electrically insulating nanofiber layer 14 .

[0050] In one of the embodiments, S110 further includes:

[0051] S112, providing a first polymer solution;

[0052] S114, making the first polymer solution into a nanofiber film by electrospinning; and

[0053] S116 , carbonizing the nanofiber film to obtain the conductive fiber layer 12 .

[0054] In step S112, the first polymer solution is preferably at least one of polyamic acid solution and polyacrylonitrile solution. The solvent in the first polymer solution may be at least one of N,N-dimethylformamide, dimethylacetamide, acetone, tetrahydrofuran, N-methylpy...

Embodiment 1

[0082] S110, prepare the conductive fiber layer 12 nanometer carbon fiber layer, including:

[0083] S112, using biphenyltetracarboxylic dianhydride (BPDA) and p-phenylenediamine (PPD), synthesize a polyamic acid solution with a mass percentage of 6% in N, N-dimethylformamide solution at -5°C ;

[0084] S114, preparing a polyamic acid nanofiber membrane by an electrospinning method. Specifically, the polyamic acid solution obtained in step S112 is added to the syringe pump, and the ambient humidity is controlled to be 30%; the syringe pump is connected to the spinning needle through a pipeline; the distance between the needle and the receiving device is 30 cm, and 25 kV is applied between the two. High-voltage electricity; through the pipeline from the syringe pump to the polymer solution in the spinning needle, the polyamic acid nanofibers are sprayed at a flow rate of 1mL / h; the polyamic acid nanofibers are collected using a receiving device to obtain polyamic acid with a t...

Embodiment 2

[0094] S110, prepare the conductive fiber layer 12 nanometer carbon fiber layer, including:

[0095] S112, preparing a polyacrylonitrile solution with a mass percentage of 15%, using N, N dimethylformamide as a solvent;

[0096] S114, preparing a polyamic acid nanofiber membrane by an electrospinning method. Add the polyacrylonitrile solution to the syringe pump, and control the ambient humidity to 50%; the syringe pump is connected to the spinning needle through a pipeline; the distance between the needle and the receiving device is 20cm, and a high voltage of 35kV is applied between the two; Polyacrylonitrile nanofibers are sprayed out from the polymer solution in the spinning needle from the syringe pump at a flow rate of 2mL / h; the polyacrylonitrile nanofibers are collected using a receiving device to obtain a polyacrylonitrile nanofiber film with a thickness of 20 μm;

[0097] S116a, preoxidizing the polyacrylonitrile nanofiber membrane to obtain a treated polyacrylonitr...

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Abstract

The invention relates to a composite separator. The composite separator comprises a conductive fiber layer and an electrical insulation nanofiber layer which are arranged in a lamination way, wherein the conductive fiber layer comprises a plurality of nanometer conductive fibers, the plurality of nanometer conductive fibers intersect to form a mesh-shaped structure, and the conductive fiber layer is provided with a plurality of micropores formed by the nanometer conductive fibers. A lithium ion battery comprises the composite separator, a positive electrode and a negative electrode, and the conductive fiber layer is arranged at one side of the negative electrode and is electrically connected with the negative electrode. The invention also relates to a fabrication method of the composite separator.

Description

technical field [0001] The invention relates to the field of batteries, in particular to a composite diaphragm, a preparation method thereof, and a lithium ion battery using the composite diaphragm. Background technique [0002] Lithium-ion batteries have the characteristics of high energy density, large output power, small self-discharge, no memory effect, long cycle life, and environmental friendliness, and are widely used in power and energy storage. The diaphragm is an important part of the lithium-ion battery, used to block the positive and negative electrodes, to prevent direct contact between the two poles and short circuit. The separator allows lithium ions to pass through and prevents electrons from flowing through, completing the transmission of lithium ions between the positive and negative electrodes during charge and discharge. The diaphragm determines the interface structure, internal resistance, battery capacity, etc. of the lithium-ion battery, and its perfo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M10/0525H01M50/403H01M50/417H01M50/423H01M50/44H01M50/443H01M50/446H01M50/457H01M50/489H01M50/491
CPCH01M10/0525H01M50/44H01M50/403H01M50/431H01M50/411H01M50/449Y02E60/10
Inventor 杨颖梁幸幸
Owner TSINGHUA UNIV
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