Balanced stepped electrode assembly, and battery cell and device comprising the same

Patent metadata

Field	Value
Publication number	US-9431674-B2
Application number	US-201414284959-A
Country	US
Kind code	B2
Filing date	May 22, 2014
Priority date	Apr 20, 2012
Publication date	Aug 30, 2016
Grant date	Aug 30, 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 units having different areas, the two or more types of 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
when 500 charge and discharge cycles have been performed at 25° C. under a charging conditions (A) and discharging conditions (B), an electrical capacitance 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 at 3V,
wherein Equation 1 is satisfied:
N n /P n ≦N n /P n+1 ,  Equation 1:

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, and
wherein Equation 4-1 is satisfied:
1.0≦ dN n /dP n ≦dN n /dP n+1 ≦1.5  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.

2. The electrode assembly of claim 1 , wherein the positive electrode and the negative electrode facing each other at the interface between the electrode units are configured to balance each other.

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 a ratio of reversible capacitance per unit area of the negative electrode to 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.

5. The electrode assembly of claim 1 , wherein Equation 1-1 is satisfied:
1≦ N n /P n ≦N n /P n+1 ,  Equation 1-1:

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.

6. The electrode assembly of claim 1 , wherein Equation 2 is satisfied:
N n /P n ≦N n /P n+1 ≦N n+1 /P n+1 ≦N n+1 /P n+2 ,  Equation 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.

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

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.

8. The electrode assembly of claim 7 , 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,
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.

9. 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.

10. The electrode assembly of claim 1 , wherein Equation 5-1 is satisfied:
1.0≦ dN n /dP n ≦dN n /dP n+1 ≦dN n+1 /dP n+1 ≦dN n+1 /dP n+2 ≦1.5  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.

11. The electrode assembly of claim 9 , wherein the electrode

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