TITLE OF INVENTION
ELECTRODE ASSEMBLY AND METHOD FOR MANUFACTURING SAME,
5 CYLINDRICAL BATTERY CELL COMPRISING ELECTRODE ASSEMBLY, AND
BATTERY PACK AND AUTOMOBILE COMPRISING CYLINDRICAL BATTERY
CELL
TECHNICAL FIELD
10 The present application claims priority to Korean Patent Application Nos. 10-2021-
0022896 and 10-2021-0183106 respectively filed on February 19, 2021 and December 20,
2021 in the Republic of Korea, the disclosures of which are incorporated herein by reference.
The present disclosure relates to an electrode assembly, a method of manufacturing
the same, a cylindrical battery cell including the electrode assembly, and a battery pack and
15 a vehicle including the cylindrical battery cell.
BACKGROUND ART
Secondary batteries have high applicability according to product groups and
electrical characteristics such as high energy density, and thus, are commonly applied not
20 only to portable devices but also to electric vehicles (EVs) or hybrid vehicles (HEVs) driven
by electric power sources.
Because secondary batteries may radically reduce the use of fossil fuel and do not
generate any by-products that come with energy consumption, the secondary batteries are
3
gaining attention as a new alternative energy source for improving eco-friendliness and
energy efficiency.
Types of secondary batteries that are currently widely used include lithium-ion
batteries, lithium polymer batteries, nickel cadmium batteries, nickel hydride batteries, and
5 nickel zinc batteries. An operating voltage of a unit secondary battery cell, that is, a unit
battery cell, ranges from about 2.5 V to about 4.5 V. Accordingly, when a higher output
voltage is required, a battery pack may be configured by connecting a plurality of battery
cells in series. Also, a battery pack may be configured by connecting a plurality of battery
cells in parallel according to charge/discharge capacity required for the battery pack.
10 Accordingly, the number of battery cells included in a battery pack and an electrical
connection type may be set in various ways according to a required output voltage and/or
charge/discharge capacity.
As types of unit secondary battery cells, cylindrical, prismatic, and pouch-type
battery cells are known. In the case of a cylindrical battery cell, a separator that is an
15 insulator is located between a positive electrode and a negative electrode, and wound to form
a jelly-roll type electrode assembly, and a battery is formed by inserting the electrode
assembly into a battery can. An electrode tab having a strip shape may be connected to an
uncoated portion of each of the positive electrode and the negative electrode, and the
electrode tab electrically connects the electrode assembly and an electrode terminal exposed
20 to the outside. For reference, a positive electrode terminal is a cap plate of a sealing body
for sealing an opening of the battery can, and a negative electrode terminal is the battery can.
However, a conventional cylindrical battery cell having such a structure has problems in that,
because current is concentrated on a strip-shaped electrode tab coupled to a positive
4
electrode uncoated portion or a negative electrode uncoated portion, resistance is high, a
large amount of heat is generated, and current collecting efficiency is poor.
For a small cylindrical battery cell having a form factor of 18650 or 21700,
resistance and heat are not a big issue. However, when a form factor is increased to apply
5 a cylindrical battery cell to an electric vehicle, a large amount of heat may be generated
around an electrode tab during a rapid charging process and the cylindrical battery cell may
catch fire.
In order to solve this problem, a cylindrical battery cell (so-called tab-less
cylindrical battery cell) having a structure in which a positive electrode uncoated portion and
10 a negative electrode uncoated portion are respectively located at an upper end and a lower
end of a jelly-roll type electrode assembly and a current collecting plate is welded to each
uncoated portion to improve current collecting efficiency has been proposed.
FIGS. 1 through 3 are views illustrating a process of manufacturing a tab-less
cylindrical battery cell. FIG. 1 illustrates a structure of an electrode plate. FIG. 2
15 illustrates a winding process of the electrode plate. FIG. 3 illustrates a process of welding
a current collecting plate to a bent surface of an uncoated portion.
Referring to FIGS. 1 through 3, a positive electrode plate 10 and a negative electrode
plate 11 have a structure in which an active material 21 is coated on a current collector 20
having a sheet shape, and include an uncoated portion 22 on a long side in a winding
20 direction X.
An electrode assembly A is manufactured by sequentially stacking the positive
electrode plate 10 and the negative electrode plate 11 along with two separators 12 as shown
in FIG. 2 and then winding the same in one direction (i.e., the winding direction X). In this
5
case, uncoated portions of the positive electrode plate 10 and the negative electrode plate 11
are located in opposite directions. Positions of the positive electrode plate 10 and the
negative electrode plate 11 may be opposite to those illustrated.
After a winding process, an uncoated portion 10a of the positive electrode plate 10
5 and an uncoated portion 11a of the negative electrode plate 11 are bent toward a core. Next,
current collecting plates 30, 31 are respectively welded to the uncoated portions 10a, 11a.
Because separate electrode tabs are not coupled to the uncoated portion 10a of the
positive electrode plate 10 and the uncoated portion 11a of the negative electrode plate 11,
the current collecting plates 30, 31 are connected to external electrode terminals, and a
10 current path having a large cross-sectional area is formed in a winding axis direction (see an
arrow) of the electrode assembly A, the resistance of the battery cell may be reduced. This
is because resistance is inversely proportional to a cross-sectional area of a path through
which current flows.

WHAT IS CLAIMED IS:
1. An electrode assembly having a jelly-roll type structure in which a first
electrode current collector and a second electrode current collector each having a sheet shape
5 and a separator located between the first electrode current collector and the second electrode
current collector are wound in one direction,
wherein at least one of the first electrode current collector and the second electrode
current collector comprises an uncoated portion exposed to outside of the separator in a
longitudinal direction of the electrode assembly on a long side end portion,
10 wherein a cutting line is formed in the longitudinal direction of the electrode
assembly in at least one of the uncoated portion of the first electrode current collector and
the uncoated portion of the second electrode current collector,
wherein the uncoated portion in which the cutting line is formed is divided into a
remaining area remaining to protrude in a winding axis direction with respect to the cutting
15 line and a bent target area bent in a preset direction,
wherein at least a part of an uncoated portion included in the bent target area is bent
to have a plurality of layers overlapping in a bending direction of a certain uncoated portion.
2. The electrode assembly according to claim 1, wherein a current collecting
20 plate having a shape corresponding to a shape of the bent target area is coupled to the
uncoated portion of the bent target area.
3. The electrode assembly according to claim 2, wherein the current collecting
50
plate is welded to the uncoated portion of the bent target area.
4. The electrode assembly according to claim 1, wherein the cutting line is
formed by cutting at least once.
5
5. The electrode assembly according to claim 4, wherein the cutting line is
formed by a cutter that ultrasonically vibrates in the winding axis direction of the electrode
assembly.
10 6. The electrode assembly according to claim 6, wherein a total height of the
current collecting plate and the uncoated portion after the current collecting plate is coupled
to the uncoated portion of the bent target area corresponds to a height of the uncoated portion
remaining to protrude in a winding axis direction of the remaining area.
15 7. The electrode assembly according to claim 6, wherein a total height of the
current collecting plate of the bent target area and the uncoated portion under the current
collecting plate is equal to a height of the uncoated portion protruding in the remaining area.
8. The electrode assembly according to claim 1, wherein there is a gap
20 between any one uncoated portion of uncoated portions of the remaining area and the other
uncoated portion.
9. The electrode assembly according to claim 8, wherein an electrolytic
51
solution flows through the gap.
10. The electrode assembly according to claim 1, wherein the certain uncoated
portion is bent along the cutting line.
5
11. The electrode assembly according to claim 1, wherein the bending direction
of the certain uncoated portion is a radial direction of the electrode assembly.
12. The electrode assembly according to claim 1, wherein the bending direction
10 of the certain uncoated portion is a core direction of the electrode assembly.
13. The electrode assembly according to claim 1, wherein a shape of the bent
target area extends in a radial direction when viewed in the winding axis direction of the
electrode assembly.
15
14. The electrode assembly according to claim 1, wherein a shape of the bent
target area is a shape radially extending outward from a core center of the electrode assembly
when viewed in the winding axis direction of the electrode assembly.
20 15. The electrode assembly according to claim 14, wherein the shape of the bent
target area is a shape radially extending outward in two or more directions from the core
center of the electrode assembly when viewed in the winding axis direction of the electrode
assembly.
52
16. The electrode assembly according to claim 1, wherein a shape of the bent
target area is a cross shape extending outward from a core center of the electrode assembly
when viewed in the winding axis direction of the electrode assembly.
5
17. The electrode assembly according to claim 1, wherein a shape of the bent
target area is a shape radially extending outward from a core center of the electrode assembly
when viewed in the winding axis direction of the electrode assembly,
wherein the cutting line has an arc shape curved toward a core of the electrode
10 assembly.
18. The electrode assembly according to claim 1, wherein at least a part of the
uncoated portion included in the bent target area is bent toward a core direction of the
electrode assembly.