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Lithium ion battery and membrane thereof

A lithium-ion battery and separator technology, applied in secondary batteries, battery pack parts, secondary battery repair/maintenance, etc., can solve the problem of uncontrollable island and linear distribution, affecting battery electrochemical performance and current density distribution Non-uniformity and other problems, to avoid uneven current density distribution, unaffected electrochemical performance, and uniform current density distribution

Inactive Publication Date: 2017-08-11
东莞市魔方新能源科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the island-like and linear distribution of the organic coating in this patent is uncontrollable, and there are defects of uneven distribution, which in turn leads to uneven distribution of current density and affects the electrochemical performance of the battery.

Method used

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  • Lithium ion battery and membrane thereof
  • Lithium ion battery and membrane thereof
  • Lithium ion battery and membrane thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0051] Preparation of positive electrode sheet:

[0052] Lithium cobaltate, conductive agent superconducting carbon (Super-P), and binder polyvinylidene fluoride (PVDF) were mixed uniformly at a mass ratio of 97:1.5:1.5 to make a lithium-ion battery cathode slurry with a certain viscosity. The slurry is coated on the aluminum foil of the current collector, and then cold pressed after drying at 85°C; then edge trimming, cutting, and slitting are performed, and after slitting, dry at 110°C for 4 hours under vacuum conditions, and weld the tabs. Made into lithium-ion battery cathode sheet.

[0053] Preparation of negative electrode sheet:

[0054] Make a slurry of graphite and conductive agent superconducting carbon (Super-P), thickener sodium carboxymethyl cellulose (CMC), and binder styrene-butadiene rubber (SBR) at a mass ratio of 96:2.0:1.0:1.0 , coated on the current collector copper foil and dried at 85°C, trimmed, cut into pieces, slitting, and dried at 110°C for 4 hours...

Embodiment 2

[0060] The difference between this embodiment and Example 1 is the preparation of diaphragm:

[0061] 1) Take a polypropylene microporous membrane with a thickness of 16 μm as the base membrane;

[0062] 2) Stir polyoxyethylene and styrene-butadiene in N-methylpyrrolidone first, the mass ratio of polyoxyethylene and styrene-butadiene is 92:8, add calcium carbonate after stirring for 2 hours, poly The mass ratio of ethylene oxide to calcium carbonate is 50:50, continue to stir for 1 hour to obtain a slurry, the solid content of the slurry is 20%, and then use dip coating to evenly coat the slurry prepared above on both sides of the base film , after drying, a polymer-coated diaphragm was obtained. The coating thickness on each side was 4 μm, and then the diaphragm was soaked in 0.5M hydrochloric acid for 30 minutes, and baked in an oven at 60 ° C for 2 hours to form an island-shaped uniform Distributed polymer coating, the area of ​​the polymer coating is 90% of the area of ​​...

Embodiment 3

[0065] The difference between this embodiment and Example 1 is the preparation of diaphragm:

[0066] 1) Take a polypropylene / polyethylene / polypropylene three-layer composite microporous membrane with a thickness of 20 μm as the base membrane;

[0067] 2) Stir polymethyl methacrylate and styrene-butadiene in deionized water first, the mass ratio of polymethacrylate to styrene-butadiene is 94:6, stir for 2 hours and then add chlorinated Ammonium, the mass ratio of polymethyl methacrylate and ammonium chloride is 50:50, continue to stir for 1h to obtain a slurry, the solid content of the slurry is 40%, and then use a touch-up to coat the slurry prepared above evenly Cover one side of the base film with a coating thickness of 3 μm, and bake the coated diaphragm in an oven at 80°C for 6 hours to form a polymer coating evenly distributed in an island shape. The area of ​​the polymer coating is the base 30% of the membrane area, and then the diaphragm is cut and cut into pieces.

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Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion battery and a membrane thereof. The membrane comprises a base membrane, wherein at least one surface of the base membrane is coated with a polymer coating; and the polymer coating is prepared into slurry by mixing and stirring a polymer, an adhesive agent and a pore forming agent in a solvent, coated on the surface of the base membrane, and uniformly distributed in an island shape. Compared with the prior art, the polymer coating in the membrane has good liquid absorption swelling capacity; an interface has good stability; the prepared lithium ion battery has an excellent mechanical property; an island-shaped distribution characteristic of the polymer coating provides a space for charging and discharging of a pole piece as well as swelling in a cycle process; and the problem of deformation of the lithium ion battery is well solved. In addition, the island-shaped polymer coating formed by the pore forming agent can be uniformly distributed on the base membrane, so that nonuniform current density distribution can be effectively avoided, and an influence on a property of the battery can be prevented.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a lithium ion battery with excellent cycle performance, safety performance and mechanical performance and a diaphragm thereof. Background technique [0002] Lithium-ion batteries are widely used in mobile phones, tablets, notebook computers and various electric vehicles due to their high energy density, high working voltage, wide operating temperature, long service life, and environmental friendliness. Even aerospace, wind energy and solar energy storage equipment. [0003] While lithium-ion batteries are widely used, there are also certain potential safety hazards. So far, there have been many accidents such as mobile phone and laptop battery explosions appearing in the newspapers, which makes people question the safety performance of lithium-ion batteries. The lithium-ion battery separator is an important part to ensure the safety performance of the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M2/16H01M10/0525H01M10/42H01M50/411H01M50/431
CPCH01M10/0525H01M10/4235H01M50/431H01M50/411Y02E60/10
Inventor 汪圣龙蒋中林
Owner 东莞市魔方新能源科技有限公司
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