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Lithium-ion battery separator prepared by polyethylene mixture and preparation method of lithium-ion battery separator

A technology of polyethylene microporous film and polyethylene, which is applied in the direction of secondary batteries, battery components, circuits, etc., can solve the unfavorable oriented lamella structure, and can not continuously and stably prepare cast base film and lamella growth Slow down the speed and other problems to achieve the effect of expanding the range of raw materials

Active Publication Date: 2014-06-25
CHANGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, when the molecular weight of the resin is low, it is not easy to form a stable oriented crystal nucleus, and a casting base film with a perfect oriented lamellar structure cannot be obtained; but if the molecular weight of the polyethylene resin is too high, it will cause melt strength and melt elasticity. If it is too high, the manufacturability of cast film forming under high draft ratio is very poor, and cast base film cannot be prepared continuously and stably; and the molecular weight of polyethylene resin is too high, which will slow down the growth rate of lamellar crystals, which is not conducive to cast base film Formation of meso-oriented lamellar structure

Method used

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  • Lithium-ion battery separator prepared by polyethylene mixture and preparation method of lithium-ion battery separator
  • Lithium-ion battery separator prepared by polyethylene mixture and preparation method of lithium-ion battery separator
  • Lithium-ion battery separator prepared by polyethylene mixture and preparation method of lithium-ion battery separator

Examples

Experimental program
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Effect test

Embodiment 1

[0074] Select the weight average molecular weight as 1.68×10 6 The ultra-high molecular weight polyethylene (UHMWPE-2) and the HDPE-3 resin in Comparative Example 1 are 5:95 according to the mass ratio (using the original, unswollen ultra-high molecular weight polyethylene UHMWPE-2 and HDPE-3 The mass ratio of the resin) is blended in two ways:

[0075] (1) Directly melt blend UHMWPE-2 and HDPE-3 resin on a twin-screw extruder;

[0076](2) First use liquid paraffin with a molecular weight of 150 as a swelling agent to swell UHMWPE-2 in a stainless steel reactor. The mass ratio of UHMWPE-2 to liquid paraffin is 10:90, and the swelling conditions are: nitrogen protection, 160°C , 12 hours; after cooling, a gel-like UHMWPE-2 was obtained. Melt and blend the jelly-like UHMWPE-2 and HDPE-3 resins on a twin-screw extruder. The temperature settings of each zone of the twin-screw extruder are: 170, 200, 220, 220, 220°C, and the head temperature is 220°C ℃. The extruded product is ...

Embodiment 2

[0084] Using the UHMWPE-2 and HDPE-3 resins in Example 1, UHMWPE-2 is swelled according to the swelling conditions in Example 1, and the jelly-like UHMWPE-2 and HDPE-3 resin obtained after cooling are processed in a twin-screw Melt blending on the extruder, the process conditions of the twin-screw extruder are the same as in Example 1, and the blending mass ratios of UHMWPE-2 and HDPE-3 are respectively: 1:99, 3:97, 7:93 and 10: 90 (both based on the mass ratio of the original, unswollen ultra-high molecular weight polyethylene UHMWPE-2 to HDPE-3 resin). According to the extrusion casting process conditions, heat treatment process conditions and cold and hot stretching process conditions in Example 1, the four kinds of blended modified resins were respectively subjected to extrusion casting film formation, heat treatment and stretching to form holes, and determined The parameters of the oriented lamellar structure of the cast base film and the performance parameters of the mic...

Embodiment 3

[0090] Select the weight average molecular weight as 1.35×10 6 , 1.97×10 6 and 2.53×10 6 The three kinds of ultra-high molecular weight polyethylene, respectively denoted as: UHMWPE-1, UHMWPE-3, UHMWPE-4. According to the swelling conditions in Example 1, the three kinds of UHMWPE were swelled, and after cooling, jelly-like UHMWPE was obtained. UHMWPE and the HDPE-3 resin in Comparative Example 1 are based on a mass ratio of 5:95 (based on the mass ratio of the original, unswollen ultra-high molecular weight polyethylene and HDPE-3 resin), in a twin-screw extrusion Melt blending was carried out on the machine, and the process conditions of the twin-screw extruder were the same as in Example 1. According to the extrusion casting process conditions, heat treatment process conditions and cold and hot stretching process conditions in Example 1, the three kinds of blended modified resins were respectively subjected to extrusion casting film formation, heat treatment and stretchi...

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Abstract

The invention discloses a lithium-ion battery separator prepared by a polyethylene mixture and a preparation method of the lithium-ion battery separator. The invention relates to a polyolefin microporous film material for the lithium-ion battery separator and a preparation method of the polyolefin microporous film material. The method comprises the following steps: fully swelling ultrahigh molecular weight polyethylene (UHMWPE) and a certain types of diluents to form UHMWPE jell; performing melt blending on a certain amount of UHMWPE jell and high-density polyethylene (HDPE) on a double-screw extruder, performing extrusion casting on a blending resin on casting equipment, and preparing a casting base film with a perfect oriented lamellar crystal structure; and performing heat treatment on the casting base film to perform cold drawing and hot drawing, and performing heat setting to prepare the polyethylene microporous film. The limitation on the range of raw material resin melt flow rate (molecular weight) range in the process of preparing the polyethylene microporous film in a conventional uniaxial stretching process is broken, the casting base film with the perfect oriented lamellar crystal structure is prepared by using polyethylene resin with wide melt flow rate range, and the polyethylene resin raw material range suitable for preparing the polyethylene microporous film in the uniaxial stretching method is widened.

Description

technical field [0001] The invention relates to a polymer functional film and its preparation technology, in particular to a polyolefin microporous membrane material used for lithium-ion battery separators and its preparation method. Background technique [0002] Lithium-ion battery separator is a polymer microporous membrane material located between the positive and negative electrodes of the lithium-ion battery. Let the ions in the electrolyte pass freely between the positive and negative electrodes to keep the electrochemical reactions of the battery orderly and reversible. [0003] Polyethylene microporous membranes have the characteristics of high mechanical strength, good stability against chemical media, and low closed-cell temperature, and have been successfully used commercially as lithium-ion battery separator materials. At present, the methods for preparing polyethylene microporous membranes in industry mainly include thermal phase separation method (wet method) ...

Claims

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Application Information

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IPC IPC(8): H01M2/16H01M50/403H01M50/417H01M50/491
CPCH01M10/0525H01M50/403H01M50/411Y02E60/10
Inventor 蒋姗沈鹏杨兴诚丁永红张洪文朱梦冰俞强
Owner CHANGZHOU UNIV
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