Prismatic secondary battery employed with safety groove

Patent metadata

Field	Value
Publication number	US-8974936-B2
Application number	US-201113306677-A
Country	US
Kind code	B2
Filing date	Nov 29, 2011
Priority date	Sep 24, 2009
Publication date	Mar 10, 2015
Grant date	Mar 10, 2015

Abstract

A prismatic secondary battery includes an electrode assembly having a cathode, an anode, and a separator mounted in a prismatic battery case in a sealed state, the battery case including a hexahedral case body open at the top thereof, the hexahedral case body being made of a metal material, and a case cap coupled to the open top of the case body, the case cap having an electrode terminal, wherein the case body is provided at a region exhibiting a stress distribution equivalent to 40% or less of the maximum stress of the case in a high pressure state with a line-shaped safety groove configured to be ruptured when high pressure occurs in the battery, and the safety groove is configured such that a residual thickness of the case body is decreased toward the middle from opposite ends of the safety groove in the longitudinal direction.

First claim

The invention claimed is:

1. A prismatic secondary battery comprising an electrode assembly consisting of a cathode, an anode, and a separator mounted in a prismatic battery case in a sealed state, the battery case comprising a hexahedral case body open at a top thereof, the hexahedral case body being made of a metal material, and a case cap coupled to the open top of the case body, the case cap having an electrode terminal, wherein
the case body has a thickness of 0.4 mm or less,
the case body has at least one surface where a vertical length of the surface is greater than a lateral width of the surface, and the surface has a vertical center axis region that extends along the vertical length,
the case body has a stress distribution when under pressure,
a safety groove having a line-shape is provided at a region of the case exhibiting a stress distribution equivalent to 40% or less of a maximum stress (S MAX ) of the case in a high pressure state, the safety groove being configured to be ruptured when high pressure occurs in the battery,
the safety groove is configured in a structure in which a vent thickness of the case body is gradually decreased toward a middle from opposite ends of the safety groove in a longitudinal direction of the safety groove,
the safety groove is formed to intersect the vertical center axis region in the surface of the case body,
the safety groove is formed in an arc shape, the arc shape of the safety groove has a radius of curvature equivalent to ½ to 1.5 times of the vertical length of the case body,
the safety groove is formed at only a middle position of the case body, the middle position having a width equivalent to ¼ to ½ of the lateral width of the case body and the safety groove is formed at an upper position of the case body, the upper position having a length equivalent to 1/20 to ⅕ of the vertical length of the case body, and
the safety groove is formed at a region of the case body corresponding to a space defined between the open top of the case body and a top of the electrode assembly mounted in the case body.

2. The prismatic secondary battery according to claim 1 , wherein the case body has a thickness of 02 to 0.4 mm.

3. The prismatic secondary battery according to claim 1 , wherein the high pressure in the battery at which the safety groove is ruptured is twice or more internal pressure of the battery in a normal condition.

4. The prismatic secondary battery according to claim 1 , wherein the safety groove is formed at a region of the case body exhibiting a stress distribution equivalent to 10 to 40% of the maximum stress (S MAX ) of the case.

5. The prismatic secondary battery according to claim 1 , wherein the safety groove is formed in an upward arc shape in which the center of curvature of the arc shape is located at an upside or in a downward arc shape in which the center of curvature of the arc shape is located at a downside.

6. The prismatic secondary battery according to claim 1 , wherein the vent thickness has an average value equivalent to 40 to 70% of the thickness of the case body.

7. The prismatic secondary battery according to claim 1 , wherein a minimum vent thickness at the middle of the safety groove is equivalent to 20 to 50% of the thickness of the case body.

8. The prismatic secondary battery according to claim 1 , wherein the vent thickness is gradually decreased toward the middle from the opposite ends of the safety groove.

9. The prismatic secondary battery according to claim 1 , wherein the vent thickness at the middle of the safety groove is equivalent to 40 to 70% of the vent thickness at the opposite ends of the safety groove.

10. The prismatic secondary battery according to claim 1 , wherein a vertical section of the safety groove is formed in a downward wedge shape.

11. The prismatic secondary battery according to claim 1 , wherein a vertical section of the safety groove is formed in a trapezoidal shape.

12. The prismatic secondary battery according to claim 1 , wherein the electrode assembly comprises a jelly-roll.

13. The prismatic secondary battery according to claim 1 , wherein the secondary battery comprises a lithium secondary battery.

14. The prismatic secondary battery according to claim 1 , wherein the at least one surface includes a front and rear side of the case body and the safety groove is provided in plural such that both the front and rear side of the case body are provided with one of the safety grooves.

Assignees

• Lee Jinsoo
• Lee Kilyoung
• Kim Jin
• Ahn Soonho
• Sung Joo-Hwan
• Lg Chemical Ltd

Inventors

• Lee Jinsoo
• Lee Kilyoung
• Kim Jin
• Ahn Soonho
• Sung Joo-Hwan

Classifications

• H01M50/133

  Thickness · CPC title

• H01M50/119

  Metals · CPC title

• Y02E30/00

  Energy generation of nuclear origin · CPC title

• H01M10/052

  Li-accumulators · CPC title

• H01M2/0285

  Electricity · mapped topic