Electrode assembly including electrode units having the same width and different lengths, and battery cell and device including the electrode assembly
View Patent ↗There are provided an electrode assembly, a battery cell including the electrode assembly, and a device including the electrode assembly. The electrode assembly includes a combination of two or more electrode units having the same width and different lengths, wherein the electrode units are stacked so that a stepped portion is formed between the electrode units, and electrodes having different polarities face each other at an interface between the electrode units.
1. An electrode assembly comprising a combination of two or more electrode units having the same width and different lengths,
wherein the electrode units are stacked so that a stepped portion is formed between the electrode units,
a positive electrode and a negative electrode face each other at an interface between the electrode units,
wherein each of the electrode units is selected from the group consisting of a single electrode, a stacked type unit cell, a jelly-roll type unit cell, a stacked and folded type unit cell, and any combination thereof, and
the electrode assembly satisfies Formula 1-2 to prevent swelling:
1≦ N n /P n ≦N n /P n+1 ≦1.2 Formula 1-2:
where n denotes an integer equal to or greater than 1,
N n denotes reversible capacity per unit area of a negative electrode of the nth longest electrode unit,
P n denotes reversible capacity per unit area of a positive electrode of the nth longest electrode unit, and
P n+1 denotes reversible capacity per unit area of a positive electrode of the (n+1)th longest electrode unit.
2. The electrode assembly of claim 1 , wherein at the interface between the electrode units having the same width and different lengths, a negative electrode of a relatively long electrode unit faces a positive electrode of a relatively short electrode unit.
3. The electrode assembly of claim 1 , wherein after 500 charging and discharging cycles at 25° C. under a charging condition (A) and a discharging condition (B), the electrode assembly has 60% or more of an electrical capacity measured after one charging and discharging cycle, and an overall thickness of the electrode assembly is varied by 15% or less as compared with an overall thickness measured after one charging and discharging cycle,
wherein in the charging condition (A), the electrode assembly is charged to a voltage of 4.2 V or 4.35 V at 1C rate in a constant current mode, and a current is supplied to the electrode assembly in a constant voltage mode until the current reaches 1/20 of a battery minimal capacity, and
in the discharging condition (B), the electrode assembly is discharged at 1C rate to a voltage of 3 V in a constant current mode.
4. The electrode assembly of claim 1 , wherein the electrode assembly satisfies Formula 2:
N n /P n ≦N n /P n+1 ≦N n+1 /P n+1 ≦N n+1 /P n+2 Formula 2:
where n denotes an integer equal to or greater than 1,
N n denotes the reversible capacity per unit area of the negative electrode of the nth longest electrode unit,
N n+1 denotes reversible capacity per unit area of a negative electrode of the (n+1)th longest electrode unit,
P n denotes the reversible capacity per unit area of the positive electrode of the nth longest electrode unit,
P n+1 denotes the reversible capacity per unit area of the positive electrode of the (n+1)th longest electrode unit, and
P n+2 denotes reversible capacity per unit area of a positive electrode of the (n+2)th longest electrode unit.
5. The electrode assembly of claim 4 , wherein the electrode assembly satisfies Formula 2-1:
1≦ N n /P n ≦N n /P n+1 ≦N n+1 /P n+1 ≦N n+1 /P n+2 Formula 2-1:
where n denotes an integer equal to or greater than 1,
N n denotes the reversible capacity per unit area of the negative electrode of the nth longest electrode unit,
N n+1 denotes the reversible capacity per unit area of the negative electrode of the (n+1)th longest electrode unit,
P n denotes the reversible capacity per unit area of the positive electrode of the nth longest electrode unit,
P n+1 denotes the reversible capacity per unit area of the positive electrode of the (n+1)th longest electrode unit, and
P n+2 denotes the reversible capacity per unit area of the positive electrode of the (n+2)th longest electrode unit.
6. The electrode assembly of claim 4 , wherein the (n+2)th longest electrode unit is disposed between the nth longest electrode unit and the (n+1)th longest electrode unit,
wherein the electrode assembly satisfies Formula 3:
N n /P n+2 ≦N n+1 /P n+2 Formula 3:
where n denotes an integer equal to or greater than 1,
N n denotes the reversible capacity per unit area of the negative electrode of the nth longest electrode unit,
N n+1 denotes the reversible capacity per unit area of the negative electrode of the (n+1)th longest electrode unit, and
P n+2 denotes the reversible capacity per unit area of the positive electrode of the (n+2)th longest electrode unit.
7. The electrode assembly of claim 1 , wherein the electrode assembly satisfies Formula 4:
dN n /dP n ≦dN n /dP n+1 Formula 4:
where n denotes an integer equal to or greater than 1,
dN n denotes a thickness of the negative electrode of the nth longest electrode unit,
dP n denotes a thickness of the positive electrode of the nth longest electrode unit, and
dP n+1 denotes a thickness of the positive electrode of the (n+1)th longest electrode unit.
8. The electrode assembly of claim 1 , wherein the electrode assembly satisfies Formula 4-1:
0.5≦ dN n /dP n ≦dN n /dP n+1 ≦2 Formula 4-1:
where n denotes an integer equal to or greater than 1,
dN n denotes a thickness of the negative electrode of the nth longest electrode unit,
dP n+1 denotes a thickness of the positive electrode of the nth longest electrode unit, and
dP n+1 denotes a thickness of the positive electrode of the (n+1)th longest electrode unit.
9. The electrode assembly of claim 1 , wherein the electrode assembly satisfies Formula 5:
dN n /dP n ≦dN n /dP n+1 ≦dN n+1 /dP n+1 ≦dN n+1 /dP n+2 Formula 5:
where n denotes an integer equal to or greater than 1,
dN n denotes a thickness of the negative electrode of the nth longest electrode unit,
dN n+1 denotes a thickness of a negative electrode of the (n+1)th longest electrode unit,
dP n denotes a thickness of the positive electrode of the nth longest electrode unit, and
dP n+1 denotes a thickness of the positive electrode of the (n+1)th longest electrode unit, and
dP n+2 denotes a thickness of a positive electrode of the (n+2)th longest electrode unit.
10. The electrode assembly of claim 1 , wherein the electrode assembly satisfies Formula 5-1:
0.5≦ dN n /dP n ≦dN n /dP n+1 ≦dN n+1 /dP n+1 ≦dN n+1 /dP n+2 ≦2 Formula 5-1:
where
n denotes an integer equal to or greater than 1,
dN n denotes a thickness of the negative electrode of the nth longest electrode unit,
dN n+1 denotes a thickness of a negative electrode of the (n+1)th longest electrode unit,
dP n denotes a thickness of the positive electrode of the nth longest electrode unit, and
dP n+1 denotes a thickness of the positive electrode of the (n+1)th longest electrode unit, and
dP n+2 denotes a thickness of a positive electrode of the (n+2)th longest electrode unit.
11. The electrode assembly of claim 9 , wherein the (n+2)th longest electrode unit is disposed between the nth longest electrode unit and the (n+1)th longest electrode unit,
wherein the electrode assembly satisfies Formula 6:
dN n /dP n+2 ≦dN n+1 /dP n+2 Formula 6:
where n denotes an integer equal to or greater than 1,
dN n denotes the thickness of the negative electrode of the nth longest electrode unit,
dN n+1 denotes the thickness of the negative electrode of the (n+1)th longest electrode unit, and
dP n+2 denotes the thickness of the positive electrode of the (n+2)th longest electrode unit.
12. The electrode assembly of claim 1 , wherein the electrode assembly comprises three or more kinds of electrode units having different lengths,
wherein a ratio of reversible capacity per unit area of a negative electrode to reversible capacity per unit area of a positive electrode facing the negative electrode at an interface between the electrode units is 1 or is increased as contact areas between the electrode units are decreased.
13. The electrode assembly of claim 1 , wherein at least one unit cell includes at least one positive electrode, at least one negative electrode, and at least one separator.
14. The electrode assembly of claim 1 , wherein electrodes and unit cells of the electrode units are partially or entirely surrounded by at least one long sheet of separation film.
15. The electrode assembly of claim 13 , wherein electrodes disposed on both outermost sides of the unit cell have the same polarity.
16. The electrode assembly of claim 13 , wherein electrodes disposed on both outermost sides of the unit cell have different polarities.
17. The electrode assembly of claim 1 , wherein each of the electrode units has a rectangular sectional shape, a rectangular sectional shape having at least one curved corner, or a sectional shape having at least one curved side.
18. The electrode assembly of claim 1 , wherein the electrode units have the same sectional shape.
19. The electrode assembly of claim 1 , wherein the electrode units comprise one or more electrode tabs, and
the electrode tabs are stacked in such a manner that electrode tabs of the same polarity are overlapped with each other.
20. The electrode assembly of claim 19 , wherein the electrode tabs have different sizes.
21. The electrode assembly of claim 1 , wherein the electrode units are arranged in such a manner that the lengths of the electrode units decrease in a direction from a lower side to an upper side of the electrode assembly.
22. The electrode assembly of claim 1 , wherein the electrode units are arranged in such a manner that the lengths of the electrode units increase in a direction from a lower side to an upper side of the electrode assembly.
23. The electrode assembly of claim 1 , wherein the longest electrode unit of the electrode units is disposed in a middle layer of the electrode assembly.
24. The electrode assembly of claim 1 , wherein the electrode units are arranged in such a manner that planar center points of the electrode units are aligned with each other.
25. The electrode assembly of claim 1 , wherein the electrode units are arranged in such a manner that planar center points of the electrode units are arranged with predetermined intervals therebetween.
26. The electrode assembly of claim 1 , wherein the electrode units are arranged in such a manner that widthwise sides of the electrode units are aligned with each other.
27. A battery cell comprising:
the electrode assembly of claim 1 and;
a battery case accommodating the electrode assembly.
28. The battery cell of claim 27 , wherein the battery case is a pouch type case.
29. The battery cell of claim 27 , wherein the battery case has a shape corresponding to a shape of the electrode assembly.
30. The battery cell of claim 27 , wherein the battery cell is a lithium ion secondary battery or a lithium ion polymer secondary battery.
31. A device comprising at least one battery cell as claimed in claim 27 .
32. The device of claim 31 , wherein a system component of the device is disposed in a remaining space of the battery cell.
33. The device of claim 32 , wherein the device is a cellular phone, a portable computer, a smartphone, a smartpad, a net book, an LEV (light electronic vehicle), an electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or a power storage device.
34. The electrode assembly of claim 1 , wherein two of the electrode units are different ones selected from the group consisting of the single electrode, the stacked type unit cell, the jelly-roll type unit cell, the stacked and folded type unit cell, and any combination thereof.