Stepped electrode assembly having predetermined a thickness ratio in the interface between electrode units, battery cell and device comprising the same

Patent metadata

Field	Value
Publication number	US-9627708-B2
Application number	US-201414497493-A
Country	US
Kind code	B2
Filing date	Sep 26, 2014
Priority date	Apr 20, 2012
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

There are provided an electrode assembly, and a battery cell, a battery pack, and a device. The electrode assembly includes a combination of two or more types of electrode units having different areas, wherein the electrode units are stacked such that steps are formed, and electrode units are formed such that a positive electrode and a negative electrode face one another at an interface between the electrode units.

First claim

The invention claimed is:

1. An electrode assembly comprising a combination of two or more types of electrode units having different areas, the electrode units being stacked so as to form a stepped portion therebetween,
wherein a positive electrode and a negative electrode are formed to face each other at an interface between the electrode units, and
Equation 4 is satisfied:
dN n /dP n ≦dN n /dP n+1 ,  Equation 4:

where n is an integer not less than 1,
dN n is a thickness of the negative electrode of the electrode unit that is the n-th largest in area,
dP n is a thickness of the positive electrode of the electrode unit that is the n-th largest in area, and
dP n+1 is a thickness of the positive electrode of the electrode unit that is the (n+1)th largest in area.

2. An electrode assembly of claim 1 , wherein Equation 4-1 is satisfied:
0.5≦ dN n /dP n ≦dN n /dP n+1 ≦2  Equation 4-1:

where n is an integer not less than 1,
dN n is a thickness of a negative electrode of an electrode unit that is the n-th largest in area,
dP n is a thickness of a positive electrode of an electrode unit that is the n-th largest in area, and
dP n+1 is a thickness of a positive electrode of the electrode unit that is the (n+1)th largest in area.

3. The electrode assembly of claim 1 , wherein the positive electrode of the electrode unit having a relatively small area faces the negative electrode of the electrode unit having a relatively large area at the interface between the electrode units having different areas.

4. The electrode assembly of claim 1 , wherein
when 500 charge and discharge cycles have been performed at 25° C. under charging conditions (A) and a discharging conditions (B), an electrical capacitance of the electrode assembly is 60% or more of an electrical capacitance after a single charge and discharge cycle, and a total thickness variation ratio of the electrode assembly is 15% or less:
charging conditions (A): after a battery is charged to 4.2V or 4.35V in a constant current mode of 1 C, the constant current mode is converted to a constant voltage mode, and the charging is completed after current flows until the amount of charged current becomes 1/20 of a minimum capacitance of the battery; and
discharging conditions (B): a discharge current of 1 C flows in the constant current mode, and the discharge is completed when the voltage reaches 3V.

5. The electrode assembly of claim 1 , wherein a ratio of a reversible capacitance per unit area of the negative electrode to a reversible capacitance per unit area of the positive electrode facing the negative electrode at the interface between the electrode units having different areas is not less than 1.

6. The electrode assembly of claim 1 , wherein Equation 5 is satisfied:
dN n /dP n ≦dN n /dP n+1 ≦dN n+1 /dP n+1 ≦dN n+1 /dP n+2   Equation 5:

where n is an integer not less than 1,
dN n is a thickness of the negative electrode of the electrode unit that is the n-th largest in area,
dN n+1 is a thickness of the negative electrode of the electrode unit that is the (n+1)th largest in area,
dP n is a thickness of the positive electrode of the electrode unit that is the n-th largest in area,
dP n+1 is a thickness of the positive electrode of the electrode unit that is the (n+1)th largest in area, and
dP n+2 is a thickness of the positive electrode of the electrode unit that is the (n+2)th largest in area.

7. The electrode assembly of claim 1 , wherein Equation 5-1 is satisfied:
0.5≦ dN n /dP n ≦dN n /dP n+1 ≦dN n+1 /dP n+1 ≦dN n+1 /dP n+2 ≦2  Equation 5-1:

where n is an integer not less than 1,
dN n is a thickness of the negative electrode of the electrode unit that is the n-th largest in area,
dN n+1 is a thickness of the negative electrode of the electrode unit that is the (n+1)th largest in area,
dP n is a thickness of the positive electrode of the electrode unit that is the n-th largest in area,
dP n+1 is a thickness of the positive electrode of the electrode unit that is the (n+1)th largest in area, and
dP n+2 is a thickness of the positive electrode of the electrode unit that is the (n+2)th largest in area.

8. The electrode assembly of claim 6 , wherein the electrode unit that is the (n+2)th largest in area is disposed between the electrode unit that is the n-th largest in area and the electrode unit that is (n+1)th largest in area, and
Equation 6 is satisfied,
dN n /dP n+2 ≦dN n+1 /dP n+2   Equation 6:

where n is an integer not less than 1,
dN n is a thickness of the negative electrode of the electrode unit that is the n-th largest in area,
dN n+1 is a thickness of the negative electrode of the electrode unit that is the (n+1)th largest in area,
dP n+1 is a thickness of the positive electrode of the electrode unit that is the (n+1)th largest in area, and
dP n+2 is a thickness of the positive electrode of the electrode unit that is the (n+2)th largest in area.

9. The electrode assembly of claim 1 , wherein the electrode assembly comprises a combination of three or more types of electrode unit having different areas, and
the ratios of the reversible capacitances per unit area of the negative electrodes to the reversible capacitances per unit area of the positive electrodes facing the negative electrodes at the interface between the electrode units are the same as each other or increase as the contact area between the electrode units is reduced.

10. The electrode assembly of claim 1 , wherein the positive electrode has a porosity in a range of 10% to 30%, and
the negative electrode has a porosity in a range of 15% to 50%.

11. The electrode assembly of claim 1 , wherein the electrode unit comprises: one or more single electrodes; one or more unit cells including at least one positive electrode, at least one negative electrode, and at least one separator; or any combination thereof.

12. The electrode assembly of claim 11 , wherein the unit cell is 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.

13. The electrode assembly of claim 1 , wherein the electrode assembly has a structure in which some or all of the single electrode and the unit cells constituting the electrode units are wrapped with a long sheet-type separation film.

14. The electrode assembly of claim 11 , wherein polarities of electrodes disposed on both outermost surfaces of the unit cell are the same.

15. The electrode assembly of claim 11 , wherein polarities of electrodes disposed on both outermost surfaces of the unit cell are different.

16. The electrode assembly of claim 1 , wherein a section of the electrode unit has a quadrangular shape, a quadrangular-like shape with at least one corner having a curved shape, or a shape with at least one or more sides having a curved shape.

17. The electrode assembly of claim 1 , wherein the electrode assembly includes a combination of electrode units having different sectional shapes.

18. The electrode assembly of claim 1 , wherein the electrode assembly includes a combination of electrode units having the same sectional shape.

19. The electrode assembly of claim 1 , wherein the electrode units include one or more electrode tabs, and the electrode tabs having the same polarity are connected.

20. The electrode assembly of claim 19 , wherein the electrode tabs ha

Assignees

• Lg Chemical Ltd

Inventors

• Kwon Sung-Jin
• Ahn Soon-Ho
• Kim Dong-Myung
• Kim Ki-Woong
• Kim Young-Hoon
• Yoon Sung-Han
• Ryu Seung-Min

Classifications

• H01M50/103

  prismatic or rectangular (H01M50/109, H01M50/11 take precedence) · CPC title

• H01M2010/4292

  Aspects relating to capacity ratio of electrodes/electrolyte or anode/cathode · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M10/0585

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

• H01M2220/10

  Batteries in stationary systems, e.g. emergency power source in plant · CPC title