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

Patent metadata

Field	Value
Publication number	US-9263760-B2
Application number	US-201514707850-A
Country	US
Kind code	B2
Filing date	May 8, 2015
Priority date	Apr 20, 2012
Publication date	Feb 16, 2016
Grant date	Feb 16, 2016

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 unit having different areas, the two or more types of electrode unit 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, satisfying following Equation 1-2 so that N/P ratio at the interface is balanced:
1≦ N n /P n ≦N n /P n+1 ≦1.2,  Equation 1-2:

where n is an integer not less than 1,
N n is reversible capacitance per unit area of the negative electrode of the electrode unit that is the n-th largest in area,
P n is reversible capacitance per unit area of the positive electrode of the electrode unit that is the n-th largest in area, and
P n+1 is reversible capacitance per unit area of the positive electrode of the electrode unit that is the (n+1)th largest in area.

2. The electrode assembly according to claim 1 , wherein Equation 2-2 is satisfied:
1≦ N n /P n ≦N n /P n+1 ≦N n+1 /P n+1 ≦N n+1 /P n+2 ≦1.2  Equation 2-2:

where n is an integer not less than 1,
N n is reversible capacitance per unit area of a negative electrode of the electrode unit that is the n-th largest in area,
N n+1 is reversible capacitance per unit area of a negative electrode of the electrode unit that is the (n+1)th largest in area,
P n is reversible capacitance per unit area of a positive electrode of the electrode unit that is the n-th largest in area,
P n+1 is reversible capacitance per unit area of the positive electrode of the electrode unit that is the (n+1)th largest in area, and
P n+2 is reversible capacitance per unit area of a positive electrode of an electrode unit that is the (n+2)th largest in area.

3. The electrode assembly according to claim 1 , 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 3 is satisfied,
N n /P n+2 ≦N n+1 /P n+2   Equation 3:

where n is an integer not less than 1,
N n is reversible capacitance per unit area of a negative electrode of the electrode unit that is the n-th largest in area,
N n+1 is reversible capacitance per unit area of a negative electrode of the electrode unit that is the (n+1)th largest in area, and
P n+2 is reversible capacitance per unit area of a positive electrode of an electrode unit that is the (n+2)th largest in area.

4. The electrode assembly according to claim 1 , wherein at the interface between the electrode units having different areas, a negative electrode of an electrode unit having a relatively large area and a positive electrode of an electrode unit having a relatively small area face one another.

5. The electrode assembly according to claim 1 , wherein the reversible capacitance per unit area of the negative electrode is a value defined as a charge capacitance of the negative electrode per unit area [mAh/cm 2 ]×efficiency [%] of the negative electrode and the reversible capacitance per unit area of the positive electrode is a value defined as a loaded amount [g/cm 2 ] of a positive electrode active material×a charge capacitance [mAh/g] per unit weight of positive electrode−an irreversible capacitance [mAh] per unit area of negative electrode.

6. The electrode assembly according to claim 1 , wherein
when 500 charge and discharge cycles have been performed at 25° C. under charging conditions (A) and 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 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 discharging is completed when the voltage reaches at 3V.

7. The electrode assembly according to claim 1 , wherein a ratio of a thickness of the negative electrode to a thickness of the negative electrode facing the positive electrode at the interface between the electrode units is in a range of 0.5 to 2.

8. The electrode assembly according to 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%.

9. The electrode assembly according to claim 1 , wherein Equation 4 is satisfied:
dN n /dP n ≦dN n /dP n+   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.

10. The electrode assembly according to claim 9 , 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 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.

11. The electrode assembly according to claim 9 , 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.

12. The electrode assembly according to claim 10 , wherein Equation 5-1 is satisfied:
0.5 ≦N 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.

13. The electrode assembly according to claim 11 , 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

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