Battery diaphragm and fabrication method thereof

A technology for battery diaphragms and diaphragms, which is applied in the field of power battery diaphragms and its preparation, and can solve the problem of battery diaphragm air permeability, high-temperature membrane rupture temperature, high closed-cell temperature of polyvinylidene fluoride non-woven diaphragm, puncture pull Poor tensile strength and other problems

Active Publication Date: 2012-12-12
BYD CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] In order to solve the technical problems of unsatisfactory air permeability and high-temperature membrane rupture temperature of the existing battery diaphragm, excessively high closed cell temperature of the polyvinylidene fluoride non-woven diaphragm, and poor pie

Method used

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Examples

Experimental program
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Effect test

preparation example Construction

[0024] The present invention also provides a method for preparing a battery diaphragm, comprising the following steps:

[0025] (a) mixing ultra-high molecular weight polyethylene and linear low-density polyethylene, placing them in a second solvent after mixing, heating and stirring to dissolve, and obtaining a mixed solution;

[0026] (b) Coating the mixed solution on both sides of the polyvinylidene fluoride nonwoven fabric to obtain a coated membrane;

[0027] (c) Stretching the coated membrane to obtain a stretched membrane;

[0028] (d) heat-setting the stretched membrane to obtain a separator;

[0029] The second solvent is a good solvent for polyolefin, which refers to a solvent close to the polarity of polyolefin, preferably, selected from decahydronaphthalene, kerosene, benzene, toluene, chloroform, ether, trichloroethylene, paraffin or liquid paraffin one or more.

[0030] In the preparation method of the battery separator provided by the present invention, prefe...

Embodiment 1

[0053] The diaphragm in this example is made through the following steps:

[0054] (s1) 4kg, weight average molecular weight is 3.7×10 5 1. Mix polyvinylidene fluoride with a molecular weight distribution of 2.4, 32kg N,N-dimethylformamide, and 4kg acetone, add it to a stirring tank, heat up to 60°C at a stirring rate of 50r / min, heat and stir for 1h, and ultrasonically Degassing and standing for 2h to obtain polyvinylidene fluoride spinning solution;

[0055] (s2) Inject the spinning liquid obtained in (s1) into the tee pipe in the high-voltage electrospinning device, connect the spinneret to the anode output end of the high-voltage power supply, connect the cathode output end to the metal receiving plate, and turn on the high-voltage power supply 13KV , preheat for 30min, adjust the spinning voltage and the distance between the spinneret and the metal receiving plate to 15cm, start spinning to form fiber aggregates similar to non-woven fabrics, and then reinforce and compac...

Embodiment 2

[0064] The difference from Example 1 is that in step (s2), the high-voltage power supply is 20KV, and the thickness of the prepared non-woven fabric is 26 um. The obtained separator is designated as S2.

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Abstract

The invention provides a battery diaphragm. The base material of the diaphragm is a polyvinylidene fluoride non-woven fabric, coating layers are arranged on two sides of the polyvinylidene fluoride non-woven fabric, and the material of the coating layers includes an ultra high molecular weight polyethylene and a linear low density polyethylene. A fabrication method of the battery diaphragm is further provided. According to the battery diaphragm and the fabrication method thereof, the provided battery diaphragm has the advantages that the air permeability is remarkably improved, the closed pore temperature is remarkably lowered, the puncture strength and diaphragm breaking temperature are remarkably improved, a safe protective property is provided for a battery, and the battery diaphragm is applicable to power batteries.

Description

technical field [0001] The invention relates to a battery separator, in particular to a separator for a power battery and a preparation method thereof. Background technique [0002] Lithium ion secondary battery is a kind of battery with extremely high energy density, but there is a danger of explosion due to short circuit. In lithium-ion secondary batteries, the separator is mainly used for the conduction of lithium ions, and separates the positive and negative electrodes inside the battery from each other, so as to prevent battery self-discharge and short-circuit of the two poles, and play a certain role in safety protection. The thermal stability, permeability, porosity, and film thickness of the separator all have an important impact on the performance of the battery. [0003] In recent years, the application of lithium-ion secondary batteries has been extended to fields such as hybrid electric vehicles, and the thermal stability requirements for separators are becoming...

Claims

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Application Information

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IPC IPC(8): H01M2/16B32B27/08B32B27/30B32B27/32H01M50/417H01M50/426H01M50/454H01M50/457H01M50/489H01M50/491
CPCY02E60/12H01M2/1686H01M10/0525H01M2/162H01M2/1653Y02T10/7011Y02E60/10H01M50/417H01M50/454H01M50/457H01M50/491H01M50/489H01M50/426H01M50/44
Inventor 林妙云尤臻于伟成罗明俊刘会权
Owner BYD CO LTD
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