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Battery diaphragm and preparation method thereof

A technology for battery separators and polyolefin microporous membranes, which is applied to battery components, circuits, electrical components, etc., can solve the problem of not responding quickly and protecting battery safety, high closed-cell temperature of dry-process polypropylene separators, and melting To avoid problems such as slow fluid flow, achieve good safety, improve tensile strength and puncture strength, and avoid potential safety hazards

Inactive Publication Date: 2019-05-24
武汉中兴创新材料技术有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing wet-process diaphragm is usually made of ultra-high molecular weight polyethylene, the melt flow rate is slow, the thermal shrinkage is large during the heating process, and the pores cannot be closed in time
The closed cell temperature of the dry-process polypropylene separator is relatively high, and the heat shrinks greatly during the heating process, so it cannot respond quickly and protect the safety of the battery
In the dry-process polypropylene / polyethylene / polypropylene three-layer separator, although the polyethylene layer is designed as a protection, the polyethylene layer is in the middle, and it takes a certain amount of heat transfer and time to function as a circuit breaker.

Method used

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  • Battery diaphragm and preparation method thereof
  • Battery diaphragm and preparation method thereof
  • Battery diaphragm and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0038] The polyolefin microporous membrane preparation device of this example, wherein, the part that is used to prepare the middle layer of the multi-layer structure of micro-nano lamination, such as figure 1 As shown, it includes two extruders 1, co-extrusion module 5, micro-nano layer multiplier 2, extrusion die 3 and cooling traction module 4; wherein, two extruders 1 are used to extrude and prepare the middle layer respectively Polypropylene raw material and polyethylene raw material; the co-extrusion module 5 is set at the output port of the two extruders, and is used for converging and extruding the polyolefin materials extruded by the two extruders, and then transporting them to the micro-nano layer to multiply The device 2; the micro-nano layer multiplier 2 is a split layer container as a whole, which is used to divide the molten polyolefin material extruded by the co-extrusion module 5 into several strands, and then each strand forms a layer, and finally forms a plura...

Embodiment 2

[0049] In this example, the same device and method as in Example 1 were used to prepare a polyolefin microporous membrane battery separator. The surface layer is made of polypropylene with an isotacticity of 99% and a melt index of 1.5g / 10min, and the middle layer is a cross-laminated 16-layer composite of 8 layers of polypropylene layers and 8 layers of polyethylene layers formed by micro-nano lamination technology. Structure, the preparation of the 16-layer stacked intermediate layer specifically uses three micro-nano layer multipliers in series. Wherein, the polypropylene layer of the middle layer is the same as the polypropylene used in the upper surface layer, and the polyethylene layer is made of high-density polyethylene with a melt index of 0.7g / 10min. The total thickness of the polyolefin microporous membrane of this example is 16 microns, the thickness of the upper surface layer is 1 micron, the thickness of the lower surface layer is 1 micron, and the thickness of t...

Embodiment 3

[0052] In this example, the same device and method as in Example 1 were used to prepare a polyolefin microporous membrane battery separator. The surface layer is made of polypropylene with an isotacticity of 99% and a melt index of 2g / 10min, and the middle layer is a 32-layer composite structure formed by micro-nano lamination technology with 16 layers of polypropylene and 16 layers of polyethylene. The layer-stacked intermediate layer specifically adopts four series-connected micro-nano layer multipliers. Wherein, the polypropylene layer of the middle layer is the same as the polypropylene used in the upper surface layer, and the polyethylene layer is made of high-density polyethylene with a melt index of 0.3g / 10min. The total thickness of the polyolefin microporous membrane of this example is 16 microns, the thickness of the upper surface layer is 2 microns, the thickness of the lower surface layer is 2 microns, and the thickness of the middle layer is 12 microns, and the th...

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Abstract

The present invention discloses a battery diaphragm and a preparation method thereof. The battery diaphragm of the present invention comprises a micro-nano laminated polyolefin microporous membrane; the micro-nano laminated polyolefin microporous membrane is composed of an upper surface layer, a middle layer and a lower surface layer; and the middle layer is of a multilayer structure formed by polypropylene layers and polyethylene layers through a micro-nano lamination technique. According to the battery diaphragm, the middle layer of the multilayer structure formed by the polypropylene layersand the polyethylene layers through the micro-nano lamination technique is adopted, and therefore, on the one hand, the multi-layer structure has better safety, and on the other hand, the micro-nanolamination technique can assist in improving the tensile strength, puncture strength and other mechanical properties of the battery diaphragm, and can make the battery diaphragm thinner when forming the middle layer, thereby satisfying the requirements of the thin and high-safety lithium battery diaphragm for mechanical properties and safety; and distances from the polyethylene layers in the middle layer to the surface of the battery diaphragm can be adjusted, so that fast breaking functions of different effects can be realized, and therefore, the use requirements of the different breaking functions can be satisfied.

Description

technical field [0001] The present application relates to the field of lithium-ion battery separators, in particular to a battery separator and a preparation method thereof. Background technique [0002] With the development of electric vehicles and energy storage industries, the requirements for lithium batteries are getting higher and higher, requiring lithium batteries to be safer and have higher energy density. The lithium battery separator is one of the most critical materials in the lithium battery, which directly affects the safety and energy density of the lithium battery. Therefore, the preparation of a safe, environmentally friendly, thin, and low-cost microporous membrane is a difficulty in the development of the lithium battery separator. At present, there are two methods of manufacturing lithium battery separators: wet method and dry method. Among them, the wet process needs to use a large amount of organic diluent, the equipment is complicated, the cost is hig...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16B29C48/08B29C48/21H01M50/403H01M50/411H01M50/457H01M50/489
CPCY02E60/10
Inventor 王哲陈官茂姚坤刘建金
Owner 武汉中兴创新材料技术有限公司
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