Stepped electrode assembly, secondary battery including the electrode assembly, and method of manufacturing the electrode assembly

Patent metadata

Field	Value
Publication number	US-2016372781-A1
Application number	US-201414360829-A
Country	US
Kind code	A1
Filing date	Feb 6, 2014
Priority date	Feb 8, 2013
Publication date	Dec 22, 2016
Grant date	—

Abstract

There is provided a stacked and folded type electrode assembly in which at least two first electrode units having a first area and at least two second electrode units having a second area smaller than the first area are wound and stacked together with a rectangular separator. The electrode assembly includes: a first electrode stack in which the first electrode units are stacked; a second electrode stack in which the second electrode units are stacked; and a stepped portion formed by an area difference between the first electrode stack and the second electrode stack, wherein two or more layers of the separator cover the stepped portion, and the separator has the same shape as the stepped portion.

First claim

1 . A stacked and folded type electrode assembly in which at least two first electrode units having a first area and at least two second electrode units having a second area smaller than the first area are wound and stacked together with a rectangular separator, the electrode assembly comprising:
a first electrode stack in which the first electrode units are stacked; a second electrode stack in which the second electrode units are stacked; and a stepped portion formed by an area difference between the first electrode stack and the second electrode stack, wherein two or more layers of the separator cover the stepped portion, and the separator has the same shape as the stepped portion.

2 . The electrode assembly of claim 1 , wherein the layers of the separator covering the stepped portion have different thicknesses.

3 . The electrode assembly of claim 2 , wherein the separator covering the stepped portion has a thickness increasing in an inward direction.

4 . The electrode assembly of claim 3 , wherein at least an outermost layer of the separator covering the stepped portion is cut.

5 . The electrode assembly of claim 1 , wherein a thickness of the separator at a portion covering the stepped portion is 95% or less of a thickness of the separator at portions placed in the electrode stacks.

6 . The electrode assembly of claim 1 , wherein the separator covering the stepped portion is elongated.

7 . The electrode assembly of claim 1 , wherein the separator covering the stepped portion is cut.

8 . The electrode assembly of claim 1 , wherein the second electrode stack comprises an electrode stack comprising at least one electrode unit having an area smaller than the second area and disposed on the second electrode units, and the second electrode stack has at least two stepped portions.

9 . The electrode assembly of claim 1 , wherein the electrode units comprise a single electrode; a unit cell in which at least one positive electrode and at least one negative electrode are stacked with a separator disposed therebetween; or a combination thereof.

10 . The electrode assembly of claim 9 , wherein the unit cell comprises at least one selected from the group consisting of a jelly-roll type unit cell, a stacked type unit cell, a laminated and stacked type unit cell, and a stacked and folded type unit cell.

11 . The electrode assembly of claim 1 , wherein an uppermost electrode of the first electrode stack is a negative electrode.

12 . The electrode assembly of claim 1 , wherein electrodes facing each other at an interface between the first electrode stack and the second electrode assembly are different electrodes.

13 . A method of manufacturing an electrode assembly, the method comprising:
assembling an electrode assembly by arranging at least two first electrode units having a first area and at least two second electrode units having a second area smaller than the first area on a rectangular separator, and winding the separator to surround the electrode units, in such a manner that a comparatively large electrode stack formed by comparatively large electrode units and a comparatively small electrode stack formed by comparatively small electrode units are stacked to form a stepped portion therebetween, and at least two slopes of the separator having different angles are formed from ends of the comparatively small electrode units to an end of an uppermost side of the comparatively large electrode stack so as to cover the stepped portion; and removing tension of the separator covering the stepped portion so as to remove the slopes of the separator, wherein after the removing of the tension of the separator, the separator has a varying thickness.

14 . The method of claim 13 , wherein after the removing of the tension of the separator, the separator has a thickness increasing in an inward direction from an outer surface of the electrode assembly.

15 . The method of claim 13 , wherein the removing of the tension of the separator covering the stepped portion is performed by elongating the separator.

16 . The method of claim 15 , wherein the separator covering the stepped portion is elongated at 80° C. to 100° C.

17 . The method of claim 15 , wherein the separator covering the stepped portion is elongated by pressing the separator with a jig heated to 80° C. to 100° C.

18 . The method of claim 17 , wherein the jig has the same shape as the stepped portion.

19 . A second battery comprising:
the electrode assembly of claim 1 ; and a battery case in which the electrode assembly is disposed.

20 . The secondary battery of claim 19 , wherein the battery case comprises a stepped portion having the same shape as the stepped portion of the electrode assembly.

Assignees

• Lg Chemical Ltd

Inventors

• Kwon Sung-Jin
• Kim Dong-Myung
• Kim Ki-Woong
• Ahn Soon-Ho

Classifications

• H01M10/0583

  of accumulators with folded construction elements except wound ones, i.e. folded positive or negative electrodes or separators, e.g. with "Z"-shaped electrodes or separators · CPC title

• H01M2220/30

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

• H01M10/0431 Primary

  Cells with wound or folded electrodes (H01M10/045 takes precedence) · CPC title

• H01M2220/20

  Batteries in motive systems, e.g. vehicle, ship, plane · CPC title

• H01M10/0525

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