Secondary battery

Patent metadata

Field	Value
Publication number	US-12255348-B2
Application number	US-202217719837-A
Country	US
Kind code	B2
Filing date	Apr 13, 2022
Priority date	Apr 15, 2021
Publication date	Mar 18, 2025
Grant date	Mar 18, 2025

Abstract

The secondary battery includes an electrode assembly to which an electrode lead is attached; a case configured to receive the electrode assembly therein; a lead film configured to surround a part of an outer surface of the electrode lead and interposed between the electrode lead and the case; a vent region formed in at least a part of the case; and a vent member inserted into the vent region and configured to contain linear low-density polyethylene having a poly dispersity index (PDI) of 4 or less, wherein the vent member has a maximum sealing strength of less than 6 kgf/15 mm at 100° C. or above and a maximum sealing strength of 6 kgf/15 mm or more at room temperature to 60° C.

First claim

What is claimed is:

1. A secondary battery, comprising:
an electrode assembly;
an electrode lead attached to the electrode assembly;
a case configured to receive the electrode assembly therein;
a lead film configured to surround a part of an outer surface of the electrode lead, the lead film being interposed between the electrode lead and the case;
a vent region formed in at least a part of the case; and
a vent member inserted into the vent region, wherein the vent member contains linear low-density polyethylene having a poly dispersity index (PDI) of from 2.6 to 4,
wherein the vent member has a maximum sealing strength of less than 6 kgf/15 mm at from 100° C. to 120° C. and a maximum sealing strength of 6 kgf/15 mm or more at room temperature to 60° C.,
wherein the case includes a sealing portion formed to seal the electrode assembly, the sealing portion contains a sealant resin, and the linear low-density polyethylene has a lower melting point than the sealant resin,
wherein a difference between a crystallization temperature of the sealant resin and a crystallization temperature of linear low-density polyethylene is 10° C. or less,
wherein the linear low-density polyethylene is made by polymerizing in the presence of a metallocene catalyst, and wherein the linear low-density polyethylene has a crystallization temperature of 90° C. to 115° C.

2. The secondary battery according to claim 1 ,
wherein the vent member has an average sealing strength of less than 4.5 kgf/15 mm at 100° C. or above.

3. The secondary battery according to claim 1 ,
wherein the vent member has an average sealing strength of 4.5 kgf/15 mm or more at room temperature to 60° C.

4. The secondary battery according to claim 1 ,
wherein the vent member melts at 100° C. to 120° C. to vent gases.

5. The secondary battery according to claim 4 ,
wherein the vent member is vented at a pressure of 1.5 atm or more.

6. The secondary battery according to claim 1 ,
wherein the linear low-density polyethylene has a melting point of 100° C. to 130° C.

7. The secondary battery according to claim 1 ,
wherein the linear low-density polyethylene has a weight-average molecular weight of 100,000 g/mol to 400,000 g/mol.

8. The secondary battery according to claim 1 ,
wherein the vent region is located in the sealing portion.

9. The secondary battery according to claim 8 ,
wherein the vent region is located in the sealing portion at a corner of the case.

10. The secondary battery according to claim 1 ,
wherein the secondary battery is a pouch-type secondary battery.

11. The secondary battery according to claim 1 ,
wherein the vent member has an average sealing strength of less than 4.5 kgf/15 mm at 100° C. to 120° C.

12. The secondary battery according to claim 1 ,
wherein the vent member has the maximum sealing strength of less than 3 kgf/15 mm at 120° C. or more.

13. The secondary battery according to claim 1 ,
wherein the vent member has an average sealing strength of less than 2 kgf/15 mm at 120° C. or more.

14. The secondary battery according to claim 1 ,
wherein the linear low-density polyethylene has a crystallization temperature of from 105° C. to 107° C.

Assignees

• Lg Energy Solution Ltd

Inventors

• Song Dae-Woong
• Kim Sang-Hun
• Kang Min-Hyeong
• Yu Hyung-Kyun
• Lim Hun-Hee
• Hwang Soo-Ji

Classifications

• C08F210/02

  Ethene · CPC title

• C08F2500/34

  Melting point [Tm] · CPC title

• C08F2500/33

  Crystallisation temperature [Tc] · CPC title

• H01M2200/10

  Temperature sensitive devices · CPC title

• C08F2500/08

  Low density, i.e. < 0.91 g/cm3 · CPC title