Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

Preparation method for multilayer micro-porous membrane of lithium ion battery

A technology of lithium-ion batteries and microporous membranes, applied in secondary batteries, battery pack components, circuits, etc., can solve the problems of large performance differences, low transverse strength, and low permeability of microporous membranes, and achieve a multiplier Discharge performance and electrolyte retention rate are good, the degree of lateral orientation is increased, and the effect of improving overall performance

Active Publication Date: 2017-07-25
SHENZHEN SENIOR TECH MATERIAL
View PDF11 Cites 8 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The composite rollers used in the existing composite equipment are composited at room temperature, and the gas between the layers cannot be removed in time when the product is composited, forming small air bubbles, and there are differences in the degree of bonding of the composite films of each layer, resulting in bubbles during the stretching process. Part of it cannot be stretched into holes, forming a "blind hole" area, and the degree of lamination of the film is different. When stretched under force, it will form a serious "neck shrinkage". Big
[0004] In addition, the micropores of the separator prepared by the dry uniaxial stretching process are slit-shaped structures, because only a high degree of longitudinal stretching occurs during the stretching process, resulting in higher longitudinal strength of the finished microporous membrane and higher transverse strength. Small, easy to be torn by mechanical force during battery assembly and battery use, or because the lithium dendrites generated on the negative electrode material side penetrate the separator to form a short circuit or micro short circuit, which is likely to cause safety problems
The dry biaxial stretching process adds a β crystal form modifier with nucleating effect to polypropylene, and utilizes the difference in density between different phases of polypropylene to form micropores during the stretching process through crystal transformation, which is used for production Single-layer PP film, but because of the transition from β crystal form to α crystal form during its preparation process, the structure of the micropores is not easy to control, the micropore structure is uneven, and the permeability is low

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Preparation method for multilayer micro-porous membrane of lithium ion battery
  • Preparation method for multilayer micro-porous membrane of lithium ion battery
  • Preparation method for multilayer micro-porous membrane of lithium ion battery

Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0021] The embodiment of the present invention discloses a preparation method of a multilayer microporous membrane for lithium ion batteries, comprising the following steps: mixing polyolefin resin and auxiliary additives, and stirring to obtain a mixture; adding the mixture to an extruder, melting Plasticizing to obtain a melt; extruding the melt from a die head and tape-casting to obtain an intermediate film; taking multiple rolls of the intermediate film and compounding it through a compound device with a transverse stretching function to obtain a compound film For intermediates, the transverse stretching tension is 0.2-4.5N, the transverse stretching ratio is 1.0-2.5, and the temperature of the composite roll is 40-70°C; stretched to obtain a multilayer microporous membrane for lithium ion batteries.

[0022] As a preferred solution, the polyolefin resin is one or more of polypropylene, polyethylene and polyvinylidene fluoride. The auxiliary additives are one or more of p...

Embodiment 1

[0033] This embodiment provides a microporous membrane, the main raw material of which is polypropylene resin, the auxiliary materials are antistatic agent and antioxidant, the thickness of the microporous membrane is 16 μm, and the porosity is 37%. The content of the main resin polypropylene is 95% by mass percent, and the contents of the antistatic agent and antioxidant are respectively 2% and 3% by mass percent.

[0034] The method for preparing described microporous membrane, comprises the steps:

[0035] 1. Stir the main polyolefin resin and auxiliary additives evenly under certain conditions with a high-speed mixing mixer, the stirring speed is 2500rpm, and the stirring time is 20min to obtain the mixture I;

[0036] 2. Add the above mixture I into the extruder, melt and plasticize evenly under certain conditions, and the temperature of the extruder is 210°C;

[0037] 3. Extrude the cast sheet from the above melt through the die, and then enter the casting process, the ...

Embodiment 2

[0042] This embodiment provides a microporous membrane, the main raw material of which is polypropylene resin, the auxiliary materials are antistatic agent and antioxidant, the thickness of the microporous membrane is 16 μm, and the porosity is 45%. The content of the main resin polypropylene is 95% by mass percent, and the contents of the antistatic agent and antioxidant are respectively 2% and 3% by mass percent.

[0043] The method for preparing the microporous membrane is basically the same as in Example 1, except that in the fourth step of the compounding process, the temperature of the compounding roll is 65° C., and the transverse stretching ratio is 1.2.

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

PropertyMeasurementUnit
thicknessaaaaaaaaaa
thicknessaaaaaaaaaa
thicknessaaaaaaaaaa
Login to View More

Abstract

The invention provides a preparation method for a multilayer micro-porous membrane of a lithium ion battery. The method comprises the following steps: taking polyolefin resin and auxiliary additive as raw materials, fusing and plastifying, thereby acquiring a flux; extruding by a die head and performing tape casting, thereby acquiring intermediate membranes; taking multiple coils of intermediate membranes and compounding by adopting a compounding device with a horizontal stretching function, thereby acquiring a compound intermediate; and performing annealing treatment under an effect of bidirectional micro-tension and longitudinally stretching, thereby acquiring the multilayer micro-porous membrane of the lithium ion battery. According to the invention, a compounding roll is heated in a compounding process of the intermediate membranes, the inner macromolecular structure crystallization of the intermediate membranes is further perfected, and meanwhile, the intermediate membranes horizontally extend under the effect of bidirectional micro-tension and the horizontal orientation degree is increased, so that the micro-pores of the prepared micro-porous membrane are uniform, the horizontal strength is promoted, the capacity of resisting against lithium dendrite puncture is effectively promoted, the micro-short circuit phenomenon is avoided and the micro-porous membrane is suitable for large-scale production. The multilayer micro-porous membrane prepared according to the invention is high in structure uniformity and is effective in promoting the safety of the battery.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a preparation method of a multilayer microporous membrane for lithium ion batteries. Background technique [0002] The lithium-ion battery separator is an important part of the lithium-ion battery. The microporous structure, physical properties, chemical properties, and thermal properties of the separator are closely related to the performance of the battery. Due to the high operating voltage of lithium-ion batteries, the high oxidation of positive electrode materials and the high reducibility of negative electrode materials, lithium-ion battery separator materials and high electrochemical activity positive and negative electrode materials should have excellent compatibility. Excellent stability, solvent resistance, ionic conductivity, electronic insulation, good mechanical strength, high heat resistance and fusing isolation. The physical and chemical properties of...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M10/0525H01M50/403H01M50/449H01M50/489
CPCH01M10/0525H01M50/403H01M50/449H01M50/411Y02E60/10
Inventor 杨雪梅肖武华王永国高东波陈良
Owner SHENZHEN SENIOR TECH MATERIAL
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com