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A separator, its preparation method and a lithium-ion battery

A diaphragm and substrate technology, applied in the field of diaphragm, can solve the problems of increasing the migration resistance of lithium ions in the electrolyte, reducing the high temperature resistance of the battery diaphragm, and poor adhesion of sheet-shaped flexible substrates, etc., to improve the conductivity of lithium ions, Improved electrolyte resistance and perfect effect of heat-resistant layer

Active Publication Date: 2016-08-10
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the coating prepared by the above method has poor adhesion to the sheet-shaped flexible substrate. The ceramic layer and the substrate only rely on the adhesive in the ceramic layer to bond, and the bonding strength is weak. And during the charging and discharging process of the battery, the coating particles are more likely to fall off, thereby reducing the high temperature resistance of the battery separator produced according to the above method, and the falling ceramic particles will also cause uneven performance of the separator and affect the consistency of battery performance. ; It will also increase the migration resistance of lithium ions in the electrolyte, which is not conducive to fast charging and fast discharging; it may also migrate to the surface of the positive and negative electrodes, affecting the insertion and extraction of lithium ions; it may even cause pinholes in the diaphragm, causing a short circuit between the positive and negative electrodes of the battery etc., seriously affect battery performance and affect its practical application

Method used

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Examples

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preparation example Construction

[0021] The present invention also provides a method for preparing a diaphragm, the steps include:

[0022] S1. After the polymer raw material is mixed with the initiator and / or curing agent, a polymer matrix containing the initiator and / or curing agent is prepared. Among them, the mixing of the polymer raw material and the initiator and / or curing agent is not limited and preferred in the present invention. Based on the quality of the polymer raw material, the content of the initiator and / or curing agent is 0.1-1 wt%. The method for preparing a mixture of polymer raw materials and initiator and / or curing agent into a polymer substrate containing initiator and / or curing agent is not limited in the present invention, such as biaxial stretching, etc., preferably in the present invention, through spinning Prepare a polymer substrate containing initiator and / or curing agent.

[0023] S2. The ceramic slurry is attached to the surface of the polymer matrix and then cured. Preferably, ste...

Embodiment 1

[0040] This embodiment is used to illustrate the diaphragm and preparation method thereof disclosed in the present invention.

[0041] 1. Preparation of polymer matrix

[0042] Polyethylene is mixed with 0.85 wt% of dicyandiamide, and a polymer matrix containing a curing agent is prepared by a spinning method. The thickness of the prepared polymer matrix is ​​35 μm and the porosity is 50%.

[0043] 2. Preparation of slurry

[0044] Mix 1 part by weight of epoxy resin E-51 and 39 parts by weight of toluene, and then add 10 parts by weight of Al to it 2 O 3 , After fully stirring and mixing uniformly, transfer to the ball mill for ball milling to Al 2 O 3 The average particle size is 200nm, the specific surface area is 10m 2 / g, the ceramic slurry is obtained, and then the ceramic slurry is heated to 80°C for use.

[0045] 3. Prepare the slurry layer and solidify

[0046] Dip the polymer matrix obtained in step 1 into the ceramic slurry, take it out after 10 minutes, and attach 0.86μm thic...

Embodiment 2

[0048] 1. Preparation of polymer matrix

[0049] A polymer matrix containing a curing agent was prepared by mixing polypropylene with 0.73 wt% azobis-isoheptonitrile by a spinning method. The thickness of the prepared polymer matrix was 26 μm and the porosity was 71%.

[0050] 2. Preparation of slurry

[0051] Mix 1 part by weight of acrylate-terminated oligosiloxane TA10 and 42.5 parts by weight of benzene, and then add 8 parts by weight of ZnSO to it 4 , After fully stirring and mixing uniformly, transfer to the ball mill for ball milling to ZnSO 4 The average particle size is 110nm, the specific surface area is 23m 2 / g, the ceramic slurry is obtained, and then the ceramic slurry is heated to 110°C for use.

[0052] 3. Prepare the slurry layer and solidify

[0053] Dip the polymer matrix obtained in step 1 into the ceramic slurry, take it out after 8 minutes, and attach a 0.92μm thick ceramic slurry on both sides of the polymer matrix, and then place it at 100°C for curing for 20 min...

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Abstract

The invention provides a diaphragm, a preparation method thereof and a lithium ion battery containing the diaphragm. The diaphragm includes a polymer matrix and a slurry layer located inside and on the surface of the matrix. The slurry layer contains ceramic particles and a cured resin. The cross-linked resin is obtained by cross-linking and curing reaction, the diaphragm has excellent high temperature resistance, the heat-resistant layer is not easy to fall off, it is easier to wind, easier to prepare, and easier to practical application.

Description

Technical field [0001] The invention relates to a diaphragm, a preparation method thereof and a lithium ion battery. Background technique [0002] The separator of a lithium ion secondary battery is usually a thin porous insulating material, which has high ion permeability and good mechanical strength, and has long-term stability to various chemical substances and chemical solvents. Therefore, the non-conductivity of the separator is used to separate the positive and negative electrodes of the battery to prevent the two electrodes from contacting and short-circuit; at the same time, relying on the microporous structure of the separator itself allows lithium ions to pass through easily and maintain good ionic conductivity between the positive and negative electrodes. . When an abnormally large current is generated inside the battery due to an external short circuit or an incorrect connection, when the internal temperature of the battery rises to a certain level, the diaphragm wil...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M2/16H01M10/0525H01M50/403H01M50/411H01M50/414H01M50/434H01M50/451
CPCH01M10/0525H01M50/409Y02E60/10
Inventor 陈小芳苗伟峰
Owner BYD CO LTD
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