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A kind of composite polypropylene microporous membrane and its preparation method and lithium-ion battery diaphragm comprising the membrane

A technology of compounding polypropylene and microporous film, applied in the field of microporous film, can solve the problems of poor fit, low surface energy, poor wettability, etc.

Active Publication Date: 2020-09-04
BEIJING NORMAL UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the diaphragm prepared by the method is used as a lithium-ion battery diaphragm, since polypropylene is a non-polar material with low surface energy, the infiltration of the non-polar polypropylene diaphragm by the carbonate polar electrolyte in the battery poor sex
At the same time, during the battery assembly process, the non-polar polypropylene separator and the battery pole piece are also prone to poor bonding due to polarity differences

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0063] The homopolypropylene resin whose melt index is 2.5g / 10min is mixed with the polypropylene beta crystal nucleating agent N,N-dicyclohexyl-2,6 naphthalene diamide accounting for 0.03wt% of the homopolypropylene resin, and mixed uniformly in After melting at a temperature of 200-250°C, a polypropylene layer melt is formed;

[0064] Mix polyvinylidene fluoride and boehmite with a mass ratio of 3:2 evenly, that is, mix polyvinylidene fluoride accounting for 60 wt% of the total non-polypropylene layer with boehmite accounting for 40 wt% of the total non-polypropylene layer , After melting at a temperature of 200-250 ° C, a non-polypropylene layer melt is formed.

[0065] The polypropylene layer melt and the non-polypropylene layer melt are fed into the three-layer co-extrusion T-die head through the melt pipe, the polypropylene layer is on both surfaces, and the non-polypropylene layer is on the core layer. Cool and crystallize on a film roll to obtain a polypropylene film ...

Embodiment 2

[0068] Except that the composition of the polypropylene porous layer is different, the others are the same as in Example 1. The non-polypropylene layer is composed of polyvinylidene fluoride and polytetrafluoroethylene nanopowder with a mass ratio of 4:1, that is, polyvinylidene fluoride accounting for 80 wt% of the total non-polypropylene layer and 20 wt% of the total non-polypropylene layer PTFE nanopowder. The obtained composite microporous membrane had a thickness of 25 micrometers. The thicknesses of the two polypropylene microporous layers are 8 microns respectively, and the thickness of the non-polypropylene porous layer of the core layer is 9 microns.

[0069] When the composite polypropylene microporous membrane prepared above is used as a lithium-ion battery separator, the wettability and liquid absorption rate of the separator to the lithium-ion battery electrolyte are significantly improved compared with the single-layer polypropylene separator.

Embodiment 3

[0071] Unless the composition of the polypropylene layer is polyethylene terephthalate (PET) and aluminum oxide with a mass ratio of 3:2, that is, polyethylene terephthalate and aluminum oxide accounting for 60 wt% of the total non-polypropylene layer Accounting for the aluminum oxide of 40wt% of the total non-polypropylene layer, the non-polypropylene layer is on both surfaces, and the polypropylene layer is outside the core layer, and the rest of the steps are the same as in Example 1. The obtained composite microporous membrane had a thickness of 25 micrometers. The thicknesses of the two non-polypropylene porous layers are respectively 8 microns, and the thickness of the core polypropylene microporous layer is 9 microns.

[0072] When the composite polypropylene microporous membrane prepared above is used as a lithium-ion battery separator, the wettability and liquid absorption rate of the separator to the lithium-ion battery electrolyte are significantly improved compared...

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Abstract

The invention discloses a composite polypropylene microporous membrane, a preparation method thereof and a lithium-ion battery diaphragm comprising the membrane. The non-polypropylene polymer porous layer forms a film with at least two layers of structure, and the film is stretched in both longitudinal and transverse directions to realize the preparation of the composite polypropylene microporous film. The method of the invention simplifies the production process of the composite polypropylene microporous membrane, and improves the performance of the polypropylene microporous membrane. The composite polypropylene microporous membrane is used in the lithium-ion battery separator, because the non-polypropylene polymer porous layer is a polymer or composition that can form a gel with the electrolyte, or has higher heat resistance than polypropylene The polymer can improve the cycle and safety performance of lithium-ion batteries.

Description

technical field [0001] The invention belongs to the technical field of microporous membranes, and in particular relates to a composite polypropylene microporous membrane, a preparation method thereof, and a lithium ion battery diaphragm comprising the composite polypropylene microporous membrane. Background technique [0002] Polyolefin microporous membrane is a kind of polymer membrane, which is a porous membrane with a pore size between 5nm and 1000nm. It is widely used in breathable materials (such as diapers, medical dressings, clothing linings, etc.), liquid separation Materials, ultrafiltration materials, membrane filtration materials, and supercapacitor and battery diaphragm materials and other fields. [0003] There are mainly two methods for preparing polyolefin microporous membranes, one is melt extrusion stretching method (dry method), and the other is thermally induced phase separation method (TIPS, wet method). Among them, the dry stretching process can also be...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08J5/18C08L23/12C08L27/16C08L27/18C08L67/02C08K5/20C08K3/22H01M2/14H01M2/16
CPCC08J5/18C08J2323/12C08J2433/12C08J2483/04H01M50/403H01M50/449H01M50/411C08J7/0427Y02E60/10
Inventor 周建军胡志宇李林方芳
Owner BEIJING NORMAL UNIVERSITY