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High-safety diaphragm as well as preparation method and application thereof

A high-safety, diaphragm technology, applied in the battery field, can solve the problems of reducing the flexibility of the diaphragm, limited thermal stability improvement, internal short circuit, etc., to reduce the probability of thermal runaway and combustion, good thermal stability and tensile strength. , the effect of good mechanical toughness

Active Publication Date: 2022-01-07
北京金羽新材科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the battery is at a higher temperature, the diaphragm is prone to thermal shrinkage and melting, causing a short circuit between the positive and negative electrodes, which can easily cause combustion and explosion
[0004] Inorganic ceramic materials are generally high temperature resistant and non-flammable. Adding inorganic ceramic materials to the diaphragm base material can effectively improve the safety performance. The content of inorganic ceramics in the diaphragms of patents such as CN113013552A, CN102544414B, and CN110690388A is not higher than 30%, and the thermal stability The improvement is limited; the diaphragms of patents CN108470875A and CN104485438B have high ceramic content, but their tensile strength is low; patent CN109103396B prepares ceramic / polymer substrates into non-woven diaphragms, which have large pore diameters and have internal short circuits. risk
[0005] In addition, for the preparation method of the high-safety diaphragm, since the inorganic ceramic material is rigid, adding it to the diaphragm base material will reduce the flexibility of the diaphragm, and it is difficult to use the stretching method to form a film, so more flat-plate coating methods with low production efficiency are used , this method cannot carry out large-scale industrial production, which seriously hinders the production efficiency of the diaphragm

Method used

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  • High-safety diaphragm as well as preparation method and application thereof
  • High-safety diaphragm as well as preparation method and application thereof
  • High-safety diaphragm as well as preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0093] Mix polytetrafluoroethylene (molecular weight 30,000) and granular alumina (particle size 50nm) at a ratio of 40% and 60%, and after uniform dispersion for 60 minutes, add a plasticizer (volume ratio of paraffin oil to dichloromethane 3:1), control the solid content (polytetrafluoroethylene and alumina content) at 65%. After continuing to heat (50 °C) and stirring for 60 min, the solvent was evaporated to form mixed pellets. At this time, the mass proportion of the plasticizer was 20%.

[0094] The lamination is carried out by a hydraulic press, and the lamination pressure is 20MPa. The thickness of the primary sheet-shaped blank after the first lamination is 1mm; 4 layers of the primary sheet-shaped blank are stacked and laminated to form a secondary sheet-shaped blank. is 1 mm, and the thickness of each layer of secondary sheet-shaped blanks is 0.25 mm; the secondary sheet-shaped blanks are trimmed to form the sheet-shaped blanks.

[0095] The sheet-shaped blank is r...

Embodiment 2

[0099] Mix polytetrafluoroethylene (molecular weight 30000) and fibrous alumina (particle size 200nm) at a ratio of 10% and 90%, and after uniform dispersion for 60 minutes, add plasticizer (volume ratio of paraffin oil and dichloromethane 3:1), control the solid content at 50%. After continuing heating (70 °C) and stirring for 60 min, the solvent was evaporated to form mixed pellets. At this time, the mass proportion of the plasticizer was 23%.

[0100] The lamination is carried out by a hydraulic press, and the lamination pressure is 20MPa. The thickness of the primary sheet-shaped blank after the first lamination is 1mm; 4 layers of the primary sheet-shaped blank are stacked and laminated to form a secondary sheet-shaped blank. is 1 mm, and the thickness of each layer of secondary sheet-shaped blanks is 0.25 mm; the secondary sheet-shaped blanks are trimmed to form the sheet-shaped blanks.

[0101] The sheet-shaped blank is rolled by a roller press to form a diaphragm, and...

Embodiment 3

[0105] Polytetrafluoroethylene (molecular weight 40,000), polyvinylidene fluoride (molecular weight 20,000), granular alumina (particle size 50nm) and flaky montmorillonite (particle size 2μm) at 40%, 20%, 25%, Mix at a ratio of 15%, and disperse evenly for 60 minutes, then add plasticizer (dichloromethane) to control the solid content at 50%. After continuing heating (70 °C) and stirring for 60 min, the solvent was evaporated to form mixed pellets. At this time, the mass proportion of the plasticizer was 15%.

[0106] Lamination is carried out by a hydraulic press, and the lamination pressure is 20 MPa. The thickness of the primary sheet-shaped blank after the first lamination is 1 mm; stack and laminate 4 layers of the primary sheet-shaped blank to form a secondary sheet-shaped blank. Its thickness is 1 mm, and the thickness of each layer of secondary sheet-shaped blanks is 0.25 mm; the secondary sheet-shaped blanks are trimmed to form the sheet-shaped blanks.

[0107] The ...

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Abstract

The invention relates to a high-safety diaphragm as well as a preparation method and application thereof. The preparation method comprises the steps of (I) mixing a fluorocarbon polymer, an inorganic ceramic material and a plasticizer, and heating to obtain mixed granules; (II) laminating the mixture to obtain flaky blanks; (III) rolling the flaky blanks to obtain diaphragms; (IV) coating the surfaces of the diaphragms with an isolating agent, and stacking and laminating a plurality of diaphragms of which the surfaces are coated with the isolating agent to obtain a multi-layer diaphragm; (V) rolling the multi-layer diaphragm to obtain multiple films; and (VI) performing extraction pore-forming on each film, and heating to obtain the high-safety diaphragm. According to the preparation method, the requirement of fluidity of slurry can be avoided, the diaphragm with relatively high inorganic ceramic material content can be generated, and the safety of the diaphragm is effectively improved; and the yield can be improved, and the thickness and pores of the diaphragm are easy to control.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a high-safety diaphragm and its preparation method and application. Background technique [0002] Lithium-ion batteries have the characteristics of high energy density and long life. It has broad application prospects. Especially in recent years, the demand for electric vehicles has exploded, and the requirements for lithium-ion batteries have further increased. Especially the safety performance of lithium-ion batteries. [0003] The safety performance of lithium-ion batteries is closely related to the energy density it carries. The higher the energy density, the worse the safety performance. When the battery is under high temperature conditions, the diaphragm is prone to thermal shrinkage and melting, causing a short circuit between the positive and negative electrodes, which can easily cause combustion and explosion. [0004] Inorganic ceramic materials are generally hig...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M50/403H01M50/406H01M50/446H01M50/449H01M50/491H01M10/0525H01M10/42B29D7/01B29C43/30B29C33/60
CPCH01M50/403H01M50/406H01M50/446H01M50/449H01M50/491H01M10/0525H01M10/4235B29D7/01B29C43/305B29C33/60Y02E60/10
Inventor 李爱军黄杜斌王春源杨扬
Owner 北京金羽新材科技有限公司
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