Cap assembly having improved stability and cylindrical secondary battery including the same

Patent metadata

Field	Value
Publication number	US-10818959-B2
Application number	US-201615575653-A
Country	US
Kind code	B2
Filing date	Jul 21, 2016
Priority date	Jul 21, 2015
Publication date	Oct 27, 2020
Grant date	Oct 27, 2020

Abstract

The present invention relates to a cap assembly formed of a composite of cap assembly ceramic for the cylindrical battery and mounted on a top end portion of the cylindrical secondary battery in which an electrode assembly is placed in a cylindrical can, which includes a safety vent having a predetermined notch configured to be ruptured by high pressure gas generated in the battery, a current interrupt device coupled to a lower end of the safety vent and blocking a current when an internal pressure of the battery rises, and a gasket for the current interrupt device surrounding an outer circumferential surface of the current interrupt device, wherein the gasket for the current interrupt device comprises a polymer resin having a melting point of 250° C. or more and a heat deflection temperature (HDT) of 200° C. or more, and a cylindrical secondary battery including the same.

First claim

The invention claimed is:

1. A cap assembly for a cylindrical secondary battery, which is mounted on a top end portion of the cylindrical secondary battery having a structure in which an electrode assembly is placed in a cylindrical can, the cap assembly comprising:
a safety vent having a predetermined notch configured to be ruptured by high pressure gas generated in the battery;
a current interrupt device coupled to a lower end of the safety vent and blocking a current when an internal pressure of the battery rises; and
a gasket for the current interrupt device surrounding and directly contacting an outer circumferential surface of the current interrupt device,
wherein the gasket for the current interrupt device comprises a composite of a polymer resin and a ceramic material, the polymer resin having a melting point of 250° C. or more and a heat deflection temperature of 200° C. or more, the polymer resin comprising at least one polymer resin selected from the group consisting of a perfluoroalkoxy resin and a thermoplastic polyester elastomer (TPEE) having a weight-average molecular weight of 10,000 to 500,000, and
wherein the gasket for the current interrupt device has an opening at a center thereof such that the gasket for the current interrupt device does not block through holes of the current interrupt device.

2. The cap assembly for a cylindrical secondary battery of claim 1 , wherein the perfluoroalkoxy resin comprises a copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether.

3. The cap assembly for a cylindrical secondary battery of claim 2 , wherein the copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether comprises at least one selected from the group consisting of poly(tetrafluoroethylene-co-perfluoro(methylvinyl ether)), poly(tetrafluoroethylene-co-perfluoro(ethylvinyl ether)), and poly(tetrafluoroethylene-co-perfluoro(propylvinyl ether)).

4. The cap assembly for a cylindrical secondary battery of claim 1 , wherein the cap assembly has a stack structure in which the current interrupt device, the gasket for the current interrupt device, the safety vent, and a top cap having at least one gas outlet formed therein are stacked, and
a crimping gasket is further mounted on an outer circumferential surface of the stack structure.

5. The cap assembly for a cylindrical secondary battery of claim 4 , wherein the safety vent, the current interrupt device, and the gasket for the current interrupt device are disposed to communicate with each other in a straight line.

6. The cap assembly for a cylindrical secondary battery of claim 1 , wherein the safety vent, the current interrupt device, and the gasket for the current interrupt device are disposed to communicate with each other in a straight line.

7. The cap assembly for a cylindrical secondary battery of claim 1 , wherein the ceramic material includes at least one selected from the group consisting of: silicon (Si), aluminum (Al), zirconium (Zr), titanium (Ti), and insulating oxides, nitrides, hydroxides, alkoxides, and ketones of each of such elements.

8. The cap assembly for a cylindrical secondary battery of claim 7 , wherein the ceramic material includes at least one selected from the group consisting of: silica (SiO 2 ), alumina (Al 2 O 3 ), zirconium oxide (ZrO 2 ), and titanium oxide (TiO 2 ).

9. The cap assembly for a cylindrical secondary battery of claim 1 , wherein the ceramic material includes a material in which a thermal expansion coefficient at a temperature of 200° C. is 0.2% or less and in which a thermal expansion coefficient at a temperature of 400° C. in a range of 0.1% to 0.4%.

10. The cap assembly for a cylindrical secondary battery of claim 1 , wherein the polymer resin has a weight ratio to the ceramic material in the composite that is greater than or equal to 80:20.

11. A cylindrical secondary battery comprising:
an electrode assembly comprising a negative electrode, a positive electrode, and a separator;
a battery can having an opening at one side thereof and accommodating the electrode assembly and an electrolyte through the opening; and
the cap assembly of claim 1 sealing the opening of the battery can.

Assignees

• Lg Chemical Ltd

Inventors

• Park Pil Kyu
• Sung Joo Hwan
• Kang Jung Koo
• Lee Je Jun
• Song Han Gab
• Yoon yeo min

Classifications

• H01M50/195

  Composite material consisting of a mixture of organic and inorganic materials · CPC title

• H01M50/191

  Inorganic material · CPC title

• H01M50/186

  characterised by the disposition of the sealing members · CPC title

• H01M50/193

  Organic material · CPC title

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title