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Preparation method for isolating membrane of lithium ion battery

A lithium-ion battery and separator technology, applied in the field of electrochemistry, can solve the problems of complex process and high cost

Inactive Publication Date: 2017-07-04
SHANGHAI ENERGY NEW MATERIALS TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the improvement of the performance of the lithium-ion battery diaphragm in the existing technology is mainly to coat a layer of heat-resistant material on the surface of the diaphragm, and the process is relatively complicated and the cost is high.

Method used

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  • Preparation method for isolating membrane of lithium ion battery

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preparation example Construction

[0031] The preparation method of lithium-ion battery separator provided by the invention comprises steps:

[0032] The first step is to prepare cross-linkable polyethylene;

[0033] The second step is twin-screw extrusion to obtain a liquid-phase stable system;

[0034] In the third step, the cast sheet is cooled and formed;

[0035] The fourth step is stretching into a film;

[0036] The fifth step, extraction and polycondensation cross-linking;

[0037] The sixth step, the aging process.

[0038] The preparation method provided by the present invention selects polyethylene material as the base resin, completes the silane grafting reaction through a twin-screw extruder, thereby obtaining cross-linkable polyethylene, and then mixes it with a high boiling point, low molecular weight small molecule filler to form a thermodynamic The single-phase polymer solution, through cooling, the solution phase separation occurs, and the polymer solidifies into a thick sheet at the same ...

Embodiment 1

[0074] Use high-density polyethylene (HDPE, Mw=5*10 5 , melting point 124°C) as polyethylene raw material, 100 parts by weight of HDPE, 2 parts by weight of vinyltrimethoxysilane, 0.075 parts by weight of dicumyl peroxide and 0.0125 parts by weight of dibutyltin dilauric acid were mixed evenly, after precise The metering system is added to the twin-screw extruder to obtain silane-grafted polyethylene. The temperature of each section of the extruder is 140°C-180°C-200°C-210°C-200°C.

[0075] Using the silane cross-linked polyethylene prepared above as component I, the kinematic viscosity at 100°C is (7-8)mm 2 / s paraffin oil as component II. The contents of component I and component II are 30% by weight and 70% by weight respectively. The polyethylene solution is formed by melting and mixing through a twin-screw extruder (φ=30mm). The extrusion temperature is 150-250 degrees Celsius and the rotation speed is 200 rpm. The obtained solution is extruded from the die head throug...

Embodiment 2

[0077] Use high-density polyethylene (HDPE, Mw=5*10 5 , melting point 124°C) as polyethylene raw material, 100 parts by weight of HDPE, 1 part by weight of vinyltrimethoxysilane, 0.075 parts by weight of dicumyl peroxide and 0.0125 parts by weight of dibutyltin dilauric acid were mixed evenly, after accurate The metering system is added to the twin-screw extruder to obtain silane-grafted polyethylene. The temperature of each section of the extruder is 140°C-180°C-200°C-210°C-200°C.

[0078] Using the silane cross-linked polyethylene prepared above as component I, the kinematic viscosity at 100°C is (7-8)mm 2 / s paraffin oil as component II. The contents of component I and component II are 30% by weight and 70% by weight respectively. The polyethylene solution is formed by melting and mixing through a twin-screw extruder (φ=30mm). The extrusion temperature is 150-250 degrees Celsius and the rotation speed is 200 rpm. The obtained solution is extruded from the die head throug...

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Abstract

The invention discloses a preparation method for an isolating membrane of a lithium ion battery. The preparation method comprises the following steps of (1) extruding a mixed raw material to form a polyethylene solution; (2) cooling the polyethylene solution to form a sheet material; (3) stretching the sheet material to obtain a thin film; (4) performing extraction on the thin film to form a micropore membrane; and (5) performing heat setting on the micropore membrane to obtain the isolating membrane of the lithium ion battery, wherein the mixed raw material in the step (1) comprises silane grafted and modified crosslinkable polyethylene and a filling agent. The isolating membrane prepared by the preparation method disclosed by the invention is relatively low in hole-closing temperature and relatively high in membrane rupture temperature, so that the safety of a battery prepared from the membrane is effectively improved.

Description

technical field [0001] The invention relates to the field of electrochemistry, in particular to a preparation method of a lithium-ion battery separator. Background technique [0002] Lithium-ion battery separator is an electrically insulating film with nano-scale microporous structure. It is an important part of lithium batteries and plays the role of preventing positive and negative electrodes from contacting, preventing battery short circuit and transporting lithium ions. The performance of the diaphragm directly affects the rate performance, cycle life, high and low temperature performance, and safety performance of lithium batteries. [0003] The main performance parameters of battery separator include strength, heat shrinkage rate, closed cell temperature and membrane rupture temperature, etc. During the production and assembly process of battery components, the separator needs to be pulled, and after the assembly is completed, it is necessary to ensure that the separa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M10/0525C08J9/28H01M50/411H01M50/417H01M50/494
CPCH01M10/0525C08J9/28C08J2323/06H01M50/417H01M50/494Y02E60/10
Inventor 程跃孟宪伟何方波王伟强顾亮
Owner SHANGHAI ENERGY NEW MATERIALS TECH CO LTD
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