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Preparation method of polyolefin microporous membrane and polyolefin microporous membrane

A polyolefin microporous membrane and polyolefin technology, applied in electrical components, electrochemical generators, circuits, etc., can solve problems such as reduced energy density, poor interface compatibility, and increased internal resistance of batteries to improve ion transmission capabilities and energy density, the overall thickness consistency is good, and the effect of reducing tortuosity

Inactive Publication Date: 2020-05-08
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 surface coating of the separator alleviates the problem of overheating and shrinkage of the separator to a certain extent, but there are problems such as poor interface compatibility, powder falling, increased internal resistance of the battery, reduced energy density, and increased cost
Due to the special structure of the middle PE layer, the PP / PE / PP three-layer separator has the protective function of closing the closed cells at a low temperature of 130 °C, and also has high-temperature melt integrity due to the skeleton effect of the PP protective layer; but the three-layer During the use of the membrane, due to the difference in the interlayer structure, the tortuosity is relatively large, and the lithium ion transmission process is more hindered, and its cost is relatively higher.

Method used

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  • Preparation method of polyolefin microporous membrane and polyolefin microporous membrane
  • Preparation method of polyolefin microporous membrane and polyolefin microporous membrane
  • Preparation method of polyolefin microporous membrane and polyolefin microporous membrane

Examples

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Effect test

preparation example Construction

[0020] The preparation method of the present application breaks the limitation of the traditional PP / PE / PP three-layer diaphragm, and creatively uses the progressive tape casting process to prepare a double-layer composite polyolefin microporous membrane, so that the prepared double-layer composite polyolefin microporous membrane The membrane, while improving the interfacial contact, reduces the tortuosity of the double-layer composite polyolefin microporous membrane, making the resistance in the lithium ion transmission process smaller and the transmission rate faster.

[0021] The preparation method of the present application utilizes the difference in thermal stability of polyolefins of different materials, and takes into account the skeleton layer and protective layer of the prepared double-layer composite polyolefin microporous membrane through a new method of in-line casting and lamination. While improving the safety of the double-layer composite polyolefin microporous me...

Embodiment 1

[0024] In this example, the melt index is 0.8g / 10min (230°C, 2.16kg), and the density is 0.9g / cm 3 Polypropylene is used as the first component polyolefin; the melt index is 0.72g / 10min (190°C, 2.16kg), and the density is 0.96g / cm 3 The polyethylene used as the second component polyolefin; two extruders were used to extrude the first component polyolefin and the second component polyolefin respectively, and the polypropylene and Polyolefin microporous membrane with polyethylene double layer composite.

[0025] In this example, the step-by-step tape casting process is as follows: figure 1 As shown, the first component polyolefin polypropylene is extruded by the first extruder 1 to form a polypropylene casting film 01, and then conveyed to the bottom of the second extruder 3 by the transfer roller 2, the second extruder 3 Extrude the second component polyolefin polyethylene 02 on the surface of the polypropylene cast film 01 to form a cast film 03 laminated with a polypropylen...

Embodiment 2

[0036] This example uses the same method as in Example 1 to prepare a double-layer composite polyolefin microporous membrane. The difference is that the first component polyolefin in this example is poly-1-butene, and the second component polyolefin is polyolefin. 1 identical polyethylene, all the other steps are identical with embodiment 1. The thickness of the double-layer composite polyolefin microporous membrane in this example is 20 μm, wherein the thickness of the poly-1-butene layer is 10 μm, and the thickness of the polyethylene layer is 10 μm.

[0037] Similarly, the same test method as in Example 1 was used to perform thickness uniformity sequencing, tortuosity test, diaphragm lithium ion transmission resistance test and lithium ion transmission rate test on the double-layer composite polyolefin microporous membrane of this example.

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Abstract

The invention discloses a preparation method of a polyolefin microporous membrane and the polyolefin microporous membrane. The preparation method comprises the following steps: extruding a first component polyolefin by adopting a first extruder to form a first component cast film; extruding a second component polyolefin on one surface of the first component cast film by using a second extruder toform a laminated cast film; annealing, stretching and shaping the laminated cast film to obtain a double-layer composite polyolefin microporous film, wherein one of the first component polyolefin andthe second component polyolefin is polyethylene, and the other one is polypropylene, poly-1-butene or polypentene. According to the preparation method, intermittent tape casting fitting is adopted, two layers of cast films are extruded in sequence and then subjected to subsequent treatment together, so that the prepared double-layer composite polyolefin microporous film is good in overall thickness consistency, the overall tortuosity of the polyolefin microporous film is reduced, the resistance is smaller in the lithium ion transmission process, the transmission rate is higher, and the ion transmission capacity and the energy density of the polyolefin microporous film are improved.

Description

technical field [0001] The present application relates to the field of battery separators, in particular to a preparation method of a polyolefin microporous membrane and the polyolefin microporous membrane. Background technique [0002] As an important part of the lithium-ion battery, the diaphragm is used to isolate the positive and negative electrodes, prevent the short circuit of the positive and negative electrodes, and at the same time have the function of ion conduction, so that the chemical reaction can proceed smoothly. The separator has an important influence on the cycle performance, rate performance and safety performance of the battery. In order to improve the safety performance of the diaphragm, the development of diaphragm surface coating and PP / PE / PP three-layer diaphragm has become a research hotspot. The surface coating of the separator alleviates the problem of overheating and shrinkage of the separator to a certain extent, but there are problems such as p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/14H01M2/16H01M10/0525
CPCH01M10/0525H01M50/403H01M50/411Y02E60/10
Inventor 程庚刘建金姚坤范宇陈巧
Owner 武汉中兴创新材料技术有限公司
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