Battery cell having improved reliability of preventing humidity penetration

Patent metadata

Field	Value
Publication number	US-10637012-B2
Application number	US-201615735011-A
Country	US
Kind code	B2
Filing date	Jul 20, 2016
Priority date	Aug 12, 2015
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

Disclosed herein is a battery cell including a battery case, wherein the battery case includes thermally bondable portions thermally bonded to each other to constitute a first sealed portion of the battery cell, a first space for receiving an electrode assembly, and second spaces defined outside the thermally bondable portions, the second spaces constituting the outer edges of the battery case together with the thermally bondable portions, and wherein a metal piece for preventing the penetration of humidity into the first space from the outside is mounted in at least one of the second spaces.

First claim

The invention claimed is:

1. A plate-shaped battery cell having an electrode assembly received in a battery case together with an electrolyte in a state in which a periphery of the battery case is sealed, wherein the battery case comprises:
an upper portion and a lower portion each made of a respective laminate sheet comprising a resin layer and a metal layer thermally bonded to each other at thermally bondable portions of the battery case, the thermally bondable portions defining a first sealed portion of the battery cell;
a first space defined between the upper and lower portions of the battery case inside the thermally bondable portions for receiving the electrode assembly;
second spaces defined between the upper and lower portions of the battery case outside the thermally bondable portions, the second spaces extending from the thermally bondable portions to an outer edge of the battery case defined by terminal ends of the upper and lower portions, the second spaces together with the thermally bondable portions constituting the periphery of the battery case; and
a metal piece for preventing penetration of humidity into the first space from outside the battery case, the metal piece positioned in at least one of the second spaces and welded to the metal layer of the battery case so as to define a second sealed portion for preventing penetration of humidity into the first sealed portion, wherein the metal piece extends outwardly, away from the thermally bondable portions, to the outer edge of the battery case without extending beyond the outer edge.

2. The battery cell according to claim 1 , wherein
the battery case is a pouch-shaped battery case configured to have a structure in which a polypropylene layer, an aluminum layer, and one or more selected from among a nylon layer and a polyethylene terephthalate layer are sequentially stacked from an inside of the battery case toward an outside of the battery case, and
the metal piece is welded to the aluminum layer of the battery case in the at least one of the second spaces.

3. The battery cell according to claim 2 , wherein, when the aluminum layer of the battery case is exposed in the at least one of the second spaces as a result of the polypropylene layer in the at least one of the second spaces being melted by welding, the aluminum layer of the battery case is joined to the metal piece in a state in which the aluminum layer of the battery case is in tight contact with the metal piece.

4. The battery cell according to claim 2 , wherein an outer surface of the metal piece is configured to have an irregular structure in vertical section in order to increase joining force between the outer surface of the metal piece and the aluminum layer of the battery case while securing a large welding area of the outer surface of the metal piece with respect to the aluminum layer.

5. The battery cell according to claim 2 , wherein the metal piece has one or more through holes formed therein such that at least a portion of the aluminum layer melted at a time of welding is joined to the metal piece in the through holes.

6. The battery cell according to claim 2 , wherein at least a portion of the metal piece is configured to have a tapered structure in which a thickness of the at least a portion of the metal piece is gradually decreased toward the thermally bondable portions.

7. The battery cell according to claim 2 , wherein the metal piece is configured to have a structure in which an end of the metal piece facing the thermally bondable portions and a top surface and a bottom surface of the metal piece adjacent to the end of the metal piece protrude outward.

8. The battery cell according to claim 1 , wherein the metal piece has a thickness of 0.01 mm to 5 mm.

9. The battery cell according to claim 8 , wherein the metal piece has a thickness of 0.1 mm to 3 mm.

10. The battery cell according to claim 1 , wherein the metal piece is a plate having a length equivalent to 50% to 100% of a length of each of the thermally bondable portions.

11. The battery cell according to claim 1 , wherein the metal piece is made of one or more materials selected from among aluminum, copper, lead, and tin.

12. The battery cell according to claim 1 , wherein metal pieces are mounted only in the other second spaces, excluding one second space in which the electrode terminals are located.

13. The battery cell according to claim 1 , wherein metal pieces are mounted in parts of one second space in which the electrode terminals are located such that the metal pieces do not contact the electrode terminals, and are mounted in all of the other second spaces.

14. A method of manufacturing a battery cell according to claim 1 , the method comprising:
(a) receiving an electrode assembly in a first space together with an electrolyte and placing a cover and a case body such that the cover and the case body face each other to form thermally bondable portions and second spaces;
(b) thermally bonding the thermally bondable portions to form a first sealed portion;
(c) inserting a metal piece into each of the second spaces;
(d) welding the metal piece to a battery case in each of the second spaces using a welder to form a second sealed portion; and
(e) cutting the second sealed portion along a longitudinal direction thereof such that part of the second sealed portion equivalent to 30% to 90% of a width of the second sealed portion is removed.

15. The method according to claim 14 , wherein the welding is performed using an ultrasonic bonder or an ultra seam welder.

16. The method according to claim 14 , wherein
the case body defines the first space, and the cover extends from one end of the case body or is provided separately from the case body, and
the case body comprises bondable surfaces extending outward from respective ends of the first space, the bondable surfaces facing the cover to define the thermally bondable portions and the second spaces.

17. The method according to claim 16 , wherein
the thermally bondable portions are bonded so as to have a width equivalent to 20% to 50% of a width of each of the bondable surfaces, thereby constituting the first sealed portion, and
each of the second spaces is welded to the metal piece so as to have a width equivalent to 50% to 80% of the width of each of the bondable surfaces, thereby constituting a second sealed portion.

18. The method according to claim 17 , wherein the step of cutting the second sealed portion comprises cutting the second sealed portion by 50 to 90% of a width thereof in a longitudinal direction in a state in which the second sealed portion is welded to the metal piece.

19. A method of manufacturing a battery cell according to claim 1 , the method comprising:
(a) receiving an electrode assembly in a first space together with an electrolyte and placing a cover and a case body such that the cover and the case body face each other to form thermally bondable portions and second spaces;
(b) mounting a metal piece in each of the second spaces adjacent to the thermally bondable portions;
(c) welding the metal piece to a battery case in each of the second spaces using a welder and thermally bonding the thermally bondable portions using heat generated during welding to form a first sealed portion and a second sealed portion; and
(d) cutting the second sealed portion along a longitudinal direction thereof such that part of the second sealed portion equivalent to 30% to 90% of a width of the second sealed portion is removed.

20. A battery module compris

Assignees

• Lg Chemical Ltd

Inventors

• Kim Seong Min

Classifications

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• H01M10/0585

  of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators · CPC title

• H01M2/0275

  Electricity · mapped topic

• H01M2/0207

  Electricity · mapped topic