High-breakdown-strength aramid diaphragm as well as preparation method and application thereof

A technology with high breakdown strength and breakdown strength, applied in hybrid capacitor separators, hybrid/electric double layer capacitor manufacturing, structural parts, etc., can solve the problem of less attention to the breakdown strength of the diaphragm, affecting the safety performance of the battery, and short circuit of the diaphragm High efficiency and other problems, to achieve the effect of reducing the internal short circuit of the battery core, high breakdown strength, and improving safety performance

Active Publication Date: 2022-03-25
中材锂膜(宁乡)有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In the prior art, little attention has been paid to the breakdown strength of the separator, and the low breakdown strength of the separator may easily cause a high short-circuit rate of the separator in the Hi-pot process of the battery process or a short-circuit problem inside the cell during the cycle process, thereby affecting the safety performance of the battery

Method used

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  • High-breakdown-strength aramid diaphragm as well as preparation method and application thereof
  • High-breakdown-strength aramid diaphragm as well as preparation method and application thereof
  • High-breakdown-strength aramid diaphragm as well as preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0087] The para-aramid stock solution with a mass fraction of 2% and an apparent viscosity of 20,000cp and alumina powder of 3 times the mass of the aramid polymer were stirred in NMP by a high-speed dispersing emulsifier for 60 minutes, and filtered through a 1,000-mesh filter to obtain a uniform Para-aramid size.

[0088] Select a wet-process synchronous biaxially oriented polyethylene film with a thickness of 12 μm, a porosity of 38%, an air permeability of 160s / 100cc, and a breakdown voltage of 1.3kv. Coated on one side of the base film.

[0089] The diaphragm coated with aramid slurry enters the coagulation tank for pre-coagulation. The mass concentration of the NMP aqueous solution in the coagulation bath in the first coagulation tank is 25%, and the mass concentration of the NMP aqueous solution in the coagulation bath in the second coagulation tank is 5%, and the longitudinal tension in the pre-solidification process is 350N / m.

[0090] The pre-solidified aramid fibe...

Embodiment 2

[0094] The difference between this embodiment and Example 1 is that the NMP mass concentration of the coagulation bath in the first coagulation tank is 45%, the NMP mass concentration of the coagulation bath in the second coagulation tank is 15%, and the longitudinal tension of the coagulation process is 320N / m.

[0095]The obtained aramid-coated separator had a thickness of 16.2 μm, an air permeability of 244 s / 100 cc, and a breakdown voltage of 2.31 kv. The coating thickness increase value is 4.2μm, the coating air permeability increase value is 20s / 100cc / μm, and the breakdown strength of the aramid coating is 0.24kv / μm.

Embodiment 3

[0097] The difference between this embodiment and Example 1 is that the NMP mass concentration of the coagulation bath in the first coagulation tank is 30%, the NMP mass concentration of the coagulation bath in the second coagulation tank is 12%, and the longitudinal tension of the coagulation process is not controlled. .

[0098] The obtained aramid-coated separator had a thickness of 16.4 μm, an air permeability of 252 s / 100 cc, and a breakdown voltage of 2.4 kv. The coating thickness increase value is 4.4μm, the coating air permeability increase value is 21s / 100cc / μm, and the breakdown strength of the aramid coating is 0.25kv / μm.

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Abstract

The invention provides a high-breakdown-strength aramid diaphragm as well as a preparation method and application thereof, and relates to the technical field of diaphragms, the high-breakdown-strength aramid diaphragm comprises a base membrane and an aramid coating arranged on one side or two sides of the base membrane; the outer layer of the aramid fiber coating is of a dense porous structure, and the interior of the aramid fiber coating is of a fibrous porous structure; the added value of the air permeability of the aramid fiber coating of the high-breakdown-strength aramid fiber diaphragm is 20-30 s / 100 cc / mu m, and the breakdown strength of the aramid fiber coating of the high-breakdown-strength aramid fiber diaphragm is 0.24-0.3 kv / mu m. On the basis of not abnormally increasing the air permeability of the aramid fiber coating diaphragm, the breakdown strength of the diaphragm can be improved, and the safety performance is improved.

Description

technical field [0001] The invention relates to the technical field of diaphragms, in particular to an aramid diaphragm with high breakdown strength and its preparation method and application. Background technique [0002] As the key main material in the lithium-ion battery system, the diaphragm is used to isolate the positive and negative electrodes, resist electric field breakdown damage, prevent short circuit, and at the same time ensure a certain porosity and air permeability, as well as electrolyte wettability and liquid retention. Transport provides channels. The anti-breakdown ability of the separator determines the ability to block electrons, which in turn affects the safety of the battery. The porosity and air permeability of the separator can directly affect the lithium ion transport, which in turn affects the rate performance and cycle performance of the battery. [0003] In the prior art, little attention has been paid to the breakdown strength of the separator...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M10/0525H01M50/403H01M50/417H01M50/423H01M50/44H01M50/449H01M50/454H01M50/489H01M50/491H01G11/52H01G11/84
CPCH01M50/423H01M50/44H01M50/417H01M50/449H01M50/454H01M50/489H01M50/491H01M50/403H01M10/0525H01G11/52H01G11/84Y02E60/10Y02E60/13
Inventor 张影刘杲珺张绪杰李论贾国重吴奇阳徐梦白耀宗甘珊珊
Owner 中材锂膜(宁乡)有限公司
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