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Lithium ion battery diaphragm and preparation method thereof

A lithium-ion battery and separator technology, applied in battery pack parts, circuits, electrical components, etc., can solve problems such as affecting the performance of the separator, excessive thickness of the film, and uneven film thickness, and achieve uniform distribution of micropores and shrinkage. The effect of small rate and simple operation

Active Publication Date: 2013-09-04
SHANGHAI SHUANGAO ENERGY TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above formula enhances the strength of the membrane, and the diaphragm also basically meets the requirements of the lithium-ion battery for the diaphragm, but there are still the following defects: the pore size of the formed lithium-ion battery diaphragm is not uniform, which affects the performance of the diaphragm in the lithium-ion battery. Performance
[0005] The above formula and method solve the problem of uneven film thickness and excessive film thickness in the traditional technology, but there are still the following defects: the through-porosity of the membrane hole cannot exceed 70%, and the average pore diameter cannot be lower than 0.03 microns
This limits the performance of the separator in Li-ion batteries
[0006] In the past, there was a problem of uneven dissolution of raw materials in the preparation process of separators.
Specifically, due to the inhomogeneous dissolution and phase separation between the polyethylene material and mineral oil, the distribution of polyethylene in the formed lithium-ion battery separator is uneven, which in turn makes the micropores of the formed lithium-ion battery separator uneven , which cannot meet the requirements of lithium-ion battery production

Method used

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  • Lithium ion battery diaphragm and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0029] Add ultra-high molecular weight polyethylene with a molecular weight of 1 million, mineral oil with an available viscosity grade of 55, and a pore-forming agent, dioctyl phthalate, into the mixer to fully stir the raw materials at a speed of 60 RPM. The mass ratio of high molecular polyethylene is 8-9:1; the mass ratio of dioctyl phthalate and ultra-high molecular polyethylene is 9-10:1; ℃ heating and continuous extrusion to form a flat film; the flat film is cooled and formed by a cooling molding machine with a temperature of 50 °C; Stretch the flat film into a film, and the thickness of the stretched film reaches 20 μm; add n-hexane to extract the mineral oil and dioctyl phthalate in the film; heat-treat the film at a temperature of 100 ° C for 5 minutes; curl Lithium battery separators are cut and packaged.

[0030] The thickness, porosity, average pore diameter and thermal shrinkage of the diaphragm are tested using the following methods.

[0031] (1) Determinatio...

Embodiment 2

[0049] Add ultra-high molecular weight polyethylene with a molecular weight of 10 million, mineral oil with an available viscosity grade of 55, and a pore-forming agent, dioctyl phthalate, into the mixer to fully stir the raw materials at a speed of 60 RPM. The mass ratio of high molecular polyethylene is 8-9:1; the mass ratio of dioctyl phthalate and ultra-high molecular polyethylene is 9-10:1; ℃ heating and continuous extrusion to form a flat film; the flat film is cooled and formed by a cooling molding machine with a temperature of 50 °C; Stretch the flat film into a film, and the thickness of the stretched film reaches 20 μm; add n-hexane to extract the mineral oil and dioctyl phthalate in the film; heat-treat the film at a temperature of 100 ° C for 5 minutes; curl Lithium battery separators are cut and packaged.

[0050] The thickness of the lithium-ion battery separator of this embodiment measured by the above method is 20 microns, the porosity is 73%, the average pore...

Embodiment 3

[0052] Add ultra-high molecular weight polyethylene with a molecular weight of 5 million, mineral oil with an available viscosity grade of 55, and a pore-forming agent, dioctyl phthalate, into the mixer to fully stir the raw materials at a speed of 60 RPM. The mass ratio of high molecular polyethylene is 8-9:1; the mass ratio of dioctyl phthalate and ultra-high molecular polyethylene is 9-10:1; ℃ heating and continuous extrusion to form a flat film; the flat film is cooled and formed by a cooling molding machine with a temperature of 50 °C; Stretch the flat film into a film, and the thickness of the stretched film reaches 20 μm; add n-hexane to extract the mineral oil and dioctyl phthalate in the film; heat-treat the film at a temperature of 100 ° C for 5 minutes; curl Lithium battery separators are cut and packaged.

[0053] The thickness of the lithium-ion battery separator of this embodiment measured by the above method is 20 microns, the porosity is 73%, the average pore ...

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Abstract

The invention relates to a lithium ion battery diaphragm and a preparation method thereof. The method comprises the following steps of: 1) mixing ultrahigh molecular weight polyethylene, mineral oil and a pore-forming agent to form a uniform mixture; 2) heating the uniform mixture at the temperature of between 150 and 250 DEG C, and extruding continuously to form a flat diaphragm; 3) cooling the flat diaphragm at the temperature of less than 100 DEG C for forming, and stretching the flat diaphragm in horizontal and longitudinal directions simultaneously, so that the flat diaphragm is stretched to form a membrane; 4) extracting the mineral oil and the pore-forming agent from the membrane by using an extracting agent; and 5) performing heat treatment on the membrane at the temperature of between 80 and 160 DEG C to obtain the lithium ion battery diaphragm. Compared with the prior art, the lithium ion battery diaphragm has the advantages of uniform micropore distribution and pore forms, fine pore diameters, high porosity, high strength and the like.

Description

technical field [0001] The invention relates to the research field of lithium ion batteries, in particular to a lithium ion battery diaphragm and a preparation method thereof. Background technique [0002] Due to its high operating voltage and high energy density, the demand for lithium-ion secondary batteries is also increasing. Including low-end mobile phones, laptop computers, digital cameras, power tools and miner's lamps, mid-range wind power and solar energy storage, and high-end electric bicycles, electric motorcycles, electric scooters, electric wheelchairs, electric cars and electric buses, in the military There are also great applications in the aerospace field, including tanks, submarines, rockets, and lunar vehicles. Therefore, the preparation of raw materials for lithium-ion secondary batteries is becoming more and more important, and the preparation of separators is an indispensable one. [0003] US4588633 discloses a method for preparing a lithium-ion batter...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M2/18
CPCY02E60/12Y02E60/10
Inventor 吴群伟吴爱文
Owner SHANGHAI SHUANGAO ENERGY TECH
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