The present application claims the benefit of the
priority of Korean Patent Application Nos. 10-2018-0118867,
filed on October 05, 2018, and 10-2019-0122402, filed on
October 02, 2019, which are hereby incorporated by reference
in their entirety.
TECHNICAL FIELD
[0002] The present invention relate to a secondary battery.
BACKGROUND ART
[0003] Secondary batteries are rechargeable unlike primarily
batteries, and also, the possibility of compact size and high
capacity is high. Thus, recently, many studies on secondary
batteries are being carried out. As technology development
and demands for mobile devices increase, the demands for
secondary batteries as energy sources are rapidly increasing.
[0004] Secondary batteries are classified into coin type
cells, cylindrical type cells, prismatic type cells, and
pouch type cells according to a shape of a battery case. In
such a secondary battery, an electrode assembly mounted in a
battery case is a chargeable and dischargeable power
generating device having a structure in which an electrode
and a separator are stacked.
[0005] The electrode assembly may be approximately
classified into a jelly-roll type electrode assembly in which
a separator is interposed between a positive electrode and a
negative electrode, each of which is provided as the form of
3
a sheet coated with an active material, and then, the
positive electrode, the separator, and the negative electrode
are wound, a stacked type electrode assembly in which a
plurality of positive and negative electrodes with a
separator therebetween are sequentially stacked, and a
stack/folding type electrode assembly in which stacked type
unit cells are wound together with a separation film having a
long length. Among them, the jelly-roll type electrode
assembly is widely used because the jelly-roll type electrode
assembly has an advantage is easily manufactured and has high
energy density per weight.
DISCLOSURE OF THE INVENTION
TECHNICAL PROBLEM
[0006] One aspect of the present invention is to provide a
secondary battery that induce short circuit when hightemperature heat and high pressure occur to improve stability
of the battery.
TECHNICAL SOLUTION
[0007] A secondary battery according to an embodiment of the
present invention comprises an electrode assembly in which a
first electrode, a separator, and a second electrode are
alternately stacked to be wound, a can in which an
accommodation part configured to accommodate the electrode
assembly therein is formed and which comprises a first can
and a second can, which have cylindrical shapes and are
opened in a direction facing each other, and an insulator
configured to insulate an overlapping portion between the
first can and the second can, wherein the first can is
electrically connected to the first electrode, and the second
can is electrically connected to the second electrode, the
insulator is provided with a short-circuit induction through-
4
part having the form of a through-hole or a cutoff line, and
short circuit occurs between the first can and the second can
through the short-circuit induction through-part that is
deformed in shape as heat or a pressure is applied to contact
or expand the insulator.
ADVANTAGEOUS EFFECTS
[0008] According to the present invention, the first
electrode and the second electrode may be electrically
connected to the first can and the second can, and the
insulator in which the circuit-circuit induction through-part
that insulates the first can and the second can from each
other may be provided. As the high-temperature heat or the
high pressure is applied to contract and expand the insulator,
the insulator may be deformed in shape, and thus, the short
circuit may occur between the first can and the second can
through the short-circuit induction through-part. Therefore,
the energy level of the battery may be reduced to prevent the
battery from being exploded.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] FIG. 1 is a perspective view of a secondary battery
according to an embodiment of the present invention.
[0010] FIG. 2 is a cross-sectional view of the secondary
battery according to an embodiment of the present invention.
[0011] FIG. 3 is an exploded perspective view of the
secondary battery according to an embodiment of the present
invention.
[0012] FIG. 4 is a front view of the secondary battery
according to an embodiment of the present invention.
[0013] FIG. 5 is a perspective view illustrating a first
example of an insulator in the secondary battery according to
5
an embodiment of the present invention.
[0014] FIG. 6 is a perspective view illustrating a second
example of the insulator in the secondary battery according
to an embodiment of the present invention.
[0015] FIG. 7 is a perspective view illustrating a third
example of the insulator in the secondary battery according
to an embodiment of the present invention.
[0016] FIG. 8 is a perspective view illustrating a fourth
example of the insulator in the secondary battery according
to an embodiment of the present invention.
[0017] FIG. 9 is a perspective view illustrating states
before and after the insulator is deformed in the secondary
battery according to an embodiment of the present invention.
[0018] FIG. 10 is a perspective view of a secondary battery
according to another embodiment of the present invention.
[0019] FIG. 11 is an exploded perspective view of the
secondary battery according to another embodiment of the
present invention.
[0020] FIG. 12 is a perspective view of a secondary battery
according to further another embodiment of the present
invention.
[0021] FIG. 13 is an exploded perspective view of the
secondary battery according to further another embodiment of
the present invention.
[0022] FIG. 14 is a view illustrating a displacement of a
can in a secondary battery according to Manufacturing Example
1.
[0023] FIG. 15 is a view illustrating a displacement of a
can in a secondary battery according to Manufacturing Example
2.
6
[0024] FIG. 16 is a view illustrating a displacement of a
can in a secondary battery according to Comparative Example 1.
[0025] FIG. 17 is a view illustrating a displacement of a
can in a secondary battery according to Comparative Example 2.
MODE FOR CARRYING OUT THE INVENTION
[0026] The objectives, specific advantages, and novel
features of the present invention will become more apparent
from the following detailed description taken in conjunction
with the accompanying drawings. It should be noted that the
reference numerals are added to the components of the
drawings in the present specification with the same numerals
as possible, even if they are illustrated in other drawings.
Also, the present invention may be embodied in different
forms and should not be construed as limited to the
embodiments set forth herein. In the following description
of the present invention, the detailed descriptions of
related arts which may unnecessarily obscure the gist of the
present invention will be omitted.
[0027] FIG. 1 is a perspective view of a secondary battery
according to an embodiment of the present invention, and FIG.
2 is a cross-sectional view of the secondary battery
according to an embodiment of the present invention.
[0028] Referring to FISG. 1 and 2, a secondary battery 100
according to an embodiment of the present invention comprises
an electrode assembly 110 in which a first electrode 111, a
separator 114, and a second electrode 112 are alternately
stacked, a can 120 comprising a first can 121 and a second
can 122, which accommodate the electrode assembly 110 therein,
and an insulator 123 insulating an overlapping portion
between the first can 121 and the second can 122.
7
[0029] FIG. 3 is an exploded perspective view of the
secondary battery according to an embodiment of the present
invention.
[0030] Hereinafter, the secondary battery according to an
embodiment of the present invention will be described in more
detail with reference to FISG. 1 to 9.
[0031] Referring to FISG. 2 and 3, the electrode assembly
110 may be a chargeable and dischargeable power generation
element and have a structure in which an electrode 113 and
the separator 114 are combined to be alternately stacked with
each other. Here, the electrode assembly 110 may have a
wound shape.
[0032] The electrode 113 may comprise the first electrode
111 and the second electrode 112. Also, the separator 114
may separate the first electrode 111 from the second
electrode 112 to insulate the first and second electrodes 111
and 112 from each other. Here, each of the first electrode
111 and the second electrode may be provided in the form of a
sheet and then be wound together with the separator 114 so as
to be formed in a jelly roll type. Here, the electrode
assembly 110 may be wound, for example, in a cylindrical
shape.
[0033] The first electrode 111 may comprise a first
electrode collector 111a and a first electrode active
material 111b applied on the first electrode collector 111a.
Also, the first electrode 111 may comprises a first electrode
non-coating portion 111c that is not coated with the first
electrode active material 111b.
[0034] Here, the first electrode 111 may be provided as, for
example, a negative electrode and comprise a negative
8
electrode collector (not shown) and a negative electrode
active material (not shown) applied on the negative electrode
collector. Also, a negative electrode non-coating portion
that is not coated with the negative electrode active
material may be formed on the first electrode 111.
[0035] For example, the negative electrode collector may be
provided as foil made of a copper (Cu) or nickel (Ni)
material. The negative electrode active material may
comprise synthetic graphite, lithium a metal, a lithium alloy,
carbon, petroleum coke, activated carbon, graphite, a silicon
compound, a tin compound, a titanium compound, or an alloy
thereof. Here, the negative electrode active material may
further comprise, for example, non-graphite-based SiO
(silica) or SiC (silicon carbide).
[0036] The second electrode 112 may comprise a second
electrode collector 112a and a second electrode active
material 112b applied on the second electrode collector 112a.
Also, the second electrode 112 may comprises a second
electrode non-coating portion 112c that is not coated with
the second electrode active material 112b.
[0037] Here, the second electrode 112 may be provided as,
for example, a positive electrode and comprise a positive
electrode collector (not shown) and a positive electrode
active material (not shown) applied on the positive electrode
collector. Also, a positive electrode non-coating portion
that is not coated with the positive electrode active
material may be formed on the second electrode 112.
[0038] For example, the positive electrode collector may be
provided as foil made of an aluminum material, and the
positive electrode active material may be made of lithium
9
manganese oxide, lithium cobalt oxide, lithium nickel oxide,
lithium iron phosphate, or a compound or mixture thereof
containing at least one or more of the above-described
materials.
[0039] The separator 114 may be made of an insulating
material, and the first electrode 111, the separator 114, and
the second electrode 112 may be alternately stacked. Here,
the separator 114 may be disposed between the first electrode
111 and the second electrode 1 1 2 on outer surfaces of the
first electrode 111 and the second electrode 112. Here, the
separator 114 may be disposed at the outermost side in a
width direction when the electrode assembly 110 is wound.
[0040] Also, the separator 114 may be made of a flexible
material. Here, the separator 114 may be made of, for
example, a polyolefin-based resin film such as polyethylene
or polypropylene having micropores.
[0041] FIG. 4 is a front view of the secondary battery
according to an embodiment of the present invention, and FIG.
5 is a perspective view illustrating a first example of the
insulator in the secondary battery according to an embodiment
of the present invention.
[0042] Referring to FISG. 2 to 4, the can 120 may be
provided with an accommodation part that accommodates the
electrode assembly 110 therein and comprise a first can 121
and a second can 122, which have cylindrical shapes and are o
pened in a direction facing each other.
[0043] Here, the first can 121 may be electrically connected
to the first electrode 111, and the second can 122 may be
electrically connected to the second electrode 112.
[0044] Also, each of the first can 121 and the second can
10
122 may have the cylindrical shape. The first can 121 may
have an inner circumferential surface greater than an outer
circumferential surface of the second can 122 so that the
second can 122 is inserted into the first can 121.
[0045] Furthermore, the first can 121 may have one side 121b
in which a first opening (not shown) that is opened in one
direction C1 is formed and the other side 121c at which a
first connection part 121a that is closed in the other
direction C2 is formed. The second can 122 may have the
other side 122c in which a second opening 122d that is opened
in the other direction C2 is formed and one side 122b at
which a second connection part 122a that is closed in the one
direction C1 is formed. At this time, the first electrode
111 may have one end connected to the first connection part
121a, and the second electrode 112 may have one end connected
to the second connection part 122a.
[0046] Here, one end 123b of the insulator 123 may extend to
be closer to the second connection part 122a than one end of
the first can 121. Also, the other end 123c of the insulator
123 may extend to be closer to the first connection part 121a
than the other end of the second can 122. However, as
described below, when the insulator is formed to be applied
on an outer circumferential surface of the second can, the
other end 123c of the insulator 123 may match the other end
of the second can 122.
[0047] Here, a distance a between the one end of the first
can 121 to the one end 123b of the insulator 123 may be
greater than zero, and a distance b between the other end of
the second can 122 to the other end 123c of the insulator 123
may be greater than zero.
11
[0048] The insulator 123 may comprise an insulation material
to insulate the overlapping portion between the first can 121
and the second can 122.
[0049] Also, referring to FISG. 2 to 5, a short-circuit
induction through-part 123a-1 that is provided in the form of
a through-hole or a cutoff line may be formed in the
insulator 123. Here, short circuit may occur between the
first can 121 and the second can 122 through the shortcircuit induction through-part 123a-1 that is deformed in
shape when the insulator 123 is contracted or expanded by
high-temperature heat or a high pressure. Thus, an energy
level of the secondary battery 100 may be lowered to prevent
the secondary battery 100 from being exploded. This is done
because the insulator 123 is contracted or expanded when a
predetermined temperature or more and a predetermined
pressure or more are applied to the insulator 123. When the
can increases in temperature or is expanded under abnormal
situations, the insulation may also be subjected to the hightemperature heat and the high pressure, and thus, the
insulator may be contracted or expanded to be deformed in
shape.
[0050] The insulator 123 may comprise a polymer material.
Also, the polymer material may comprise, for example, any one
of polyethylene (PE), polypropylene (PP), and polyethylene
terephthalate (PET). Particularly, the polymer material may
comprise a polyethylene (PE) or polypropylene (PP) material
having a melting point at a temperature of 180°C or less.
More specifically, the polymer material may comprise, for
example, low-medium density PE having a melting point of
110°C or medium-high density PE having a melting point of
12
120°C to 180°C. Since the battery is exploded at a
temperature of about 180 degrees to 200 degrees, the
insulator made of the above-described material is used, the
short circuit may occur between the first can 121 and the
second can 122 so as to be lowered in energy level before the
battery is exploded.
[0051] Since resistance R corresponds to a value of the
product of specific resistance and area per thickness, the
resistance R of the cylindrical insulator 123 may satisfy
following equation: R = material (p) * thickness (t)/A =
material (p) * thickness (t)/(diameter (d) * height (L))
[0052] If the resistance is high, there is an advantage that
an amount of heat is suddenly reduced. However, if the
resistance is too high, an amount of heat to be generated may
be too small, and thus, the resistance may be adjusted to
have the amount of heat within a proper range. In this case,
the resistance of the insulator 123 may be adjusted by
changing the material p and the shapes d, L, and t.
[0053] For example, the insulator 123 may be applied on an
outer circumferential surface of the second can 122 to form a
coating layer. Here, the insulator 123 may be formed by
applying an insulation material on the outer circumferential
surface of the second can 122.
[0054] Furthermore, for another example, the insulator 123
may be attached to the outer circumferential surface of the
second can 122 through any one of painting, printing,
cladding, lamination, spraying, masking, dipping, and bonding.
In more detail, the insulator 123 may be formed on the outer
circumferential surface of the second can 122 through the
painting of painting the insulation material on the outer
13
circumferential surface of the second can 122, the spraying
of spraying the insulation material on the outer
circumferential surface of the second can 122, the masking of
attaching a masking agent on the outer circumferential
surface of the second can 122 or attaching the insulation
material a portion except for a mask, dipping of putting the
outer circumferential surface of the second can 122 into an
insulation solution to form an insulation layer, bonding of
allowing the insulator to adhere to the outer circumferential
surface of the second can 122 by using an adhesive component,
and the lamination of laminating the insulator 123 on the
outer circumferential surface of the second can 122.
[0055] For example, the first can 121 disposed at the
outside may comprise steel, and the second can 122 disposed
at the inside may comprise aluminum. Here, since the second
can 122 comprises the aluminum, the second can 122 may be
well expanded by the high-temperature heat. As a result, the
insulator 123 attached to the outer circumferential surface
of the second can 122 may be well expanded, and thus, the
short circuit may easily occur between the first can 121 and
the second can 122 due to the high-temperature heat through
the short-circuit induction through-part 123a-1 formed in the
insulator 123.
[0056] Here, the first electrode 111 may be provided as the
negative electrode, and the second electrode 112 may be
provided as the positive electrode.
[0057] FIG. 6 is a perspective view illustrating a second
example of the insulator in the secondary battery according
to an embodiment of the present invention, FIG. 7 is a
perspective view illustrating a third example of the
14
insulator in the secondary battery according to an embodiment
of the present invention, and FIG. 8 is a perspective view
illustrating a fourth example of the insulator in the
secondary battery according to an embodiment of the present
invention.
[0058] Referring to FIG. 5, as a first example, the shortcircuit induction through-part 123a-1 may be provided in
plurality to form at least one column in the insulator 123-1.
Particularly, the short-circuit induction through-part 123a-1
may be provided as through-holes to form the column along a
longitudinal direction of the insulator 123-1.
[0059] Referring to FIG. 6, as a second example, the shortcircuit induction through-part 123a-2 may be provided in
plurality to form at least one row in the insulator 123-2.
Particularly, the short-circuit induction through-part 123a-2
may be provided as through-holes to form the row along a
longitudinal direction of the insulator 123-2.
[0060] Referring to FIG. 7, as a third example, the shortcircuit induction through-part 123a-3 may be provided in
plurality to form a lattice shape in the insulator 123-3.
Particularly, the short-circuit induction through-part 123a-3
may be provided as through-holes.
[0061] Referring to FIG. 8, as a fourth example, the shortcircuit induction through-part 123a-4 may be provided in
plurality to be formed in the form of a cutoff line in the
insulator 123-4.
[0062] When the battery is in a normal state, the shortcircuit induction through-part may have a size that is
sufficient so that the first can and the second can do not
contact each other. When the battery is in an abnormal state,
15
the short-circuit induction through-part may be deformed in
shape so that the first can and the second can contact each
other.
[0063] FIG. 9 is a perspective view illustrating states
before and after the insulator is deformed in the secondary
battery according to an embodiment of the present invention.
Here, FIG. 9(a) illustrates a state before the insulator is
deformed, and FIG. 9(b) illustrates a state after the
insulator is deformed.
[0064] Referring to FIG. 9, it is seen that the shortcircuit induction through-part may be provided as a plurality
of through-holes so that a deformation amount of 0.10647 mm
occurs when an internal pressure is generated in the
insulator having a lattice shape.
[0065] As a result, it is seen that as the insulator is
subjected to high-temperature heat or a high pressure so as
to be contracted or expanded to be deformed in shape, causing
short circuit between the first can and the second can.
[0066] Hereinafter, a secondary battery according to another
embodiment will be described.
[0067] FIG. 10 is a perspective view of a secondary battery
according to another embodiment of the present invention, and
FIG. 11 is an exploded perspective view of the secondary
battery according to another embodiment of the present
invention.
[0068] Referring to FISG. 10 and 11, a secondary battery 200
according to another embodiment of the present invention
comprises an electrode assembly 210 in which a first
electrode 211, a separator 214, and a second electrode 212
are alternately stacked, a can 220 comprising a first can 221
16
and a second can 222, which accommodate the electrode
assembly 210 therein, and an insulator 223 insulating an
overlapping portion between the first can 221 and the second
can 222.
[0069] The secondary battery 200 according to another
embodiment of the present invention is different from the
secondary battery according to the foregoing embodiment in
materials of the first can 221 and the second can 222 and
polarities of the first electrode 211 and the second
electrode 212. Thus, contents of this embodiment, which are
duplicated with those according to the forgoing embodiment,
will be briefly described, and also, differences therebetween
will be mainly described.
[0070] In more detail, in the secondary battery 200
according to another embodiment of the present invention, the
can 220 may be provided with an accommodation part that
accommodates the electrode assembly 210 therein and comprise
a first can 221 and a second can 222, which have cylindrical
shapes and are opened in a direction facing each other.
[0071] Here, the first can 221 may be electrically connected
to the first electrode 211, and the second can 222 may be
electrically connected to the second electrode 212.
[0072] Also, each of the first can 221 and the second can
222 may have the cylindrical shape. The first can 221 may
have an inner circumferential surface greater than an outer
circumferential surface of the second can 222 so that the
second can 222 is inserted into the first can 221.
[0073] Furthermore, the first can 221 may have one side 221b
in which a first opening (not shown) that is opened in one
direction C1 is formed and the other side 221c at which a
17
first connection part 221a that is closed in the other
direction C2 is formed. The second can 222 may have the
other side 222c in which a second opening 222d that is opened
in the other direction C2 is formed and one side 222b at
which a second connection part 222a that is closed in the one
direction C1 is formed. At this time, the first electrode
211 may have one end connected to the first connection part
221a, and the second electrode 212 may have one end connected
to the second connection part 222a.
[0074] The insulator 223 may comprise an insulation material
to insulate the overlapping portion between the first can 221
and the second can 222.
[0075] Also, a short-circuit induction through-part 123a-1
that is provided in the form of a through-hole or a cutoff
line may be formed in the insulator 223. Here, short circuit
may occur between the first can 221 and the second can 222
through the short-circuit induction through-part 123a-1 that
is deformed in shape when the insulator 223 is contracted or
expanded by heat or a pressure (see FIG. 5).
[0076] Also, the first can 221 may comprise aluminum, and
the second can 222 may comprise steel. Here, the second can
222 disposed at the inside may comprise the steel, and thus,
the first can 221 and the second can 222 may be easily pressfitted with respect to each other due to physical properties
of high rigidity (it is preferable that the first can and the
second can according to the present invention are coupled to
each other in the press-fitting manner). When external force
occurs, it may be easy to protect an object to be
accommodated such as the electrode assembly 210 accommodated
into the can 220. Also, in the can 220, the first can 221
18
disposed at the outside may comprise aluminum having a high
strain rate. Thus, when the first can 221 is deformed, the
insulator may be deformed to easily cause short circuit
between the first can 221 and the second can 222 through the
short-circuit induction through-part 123a-1.
[0077] Here, the first electrode 211 may be provided as a
positive electrode, and the second electrode 212 may be
provided as a negative electrode.
[0078] Hereinafter, a secondary battery according to further
another embodiment will be described.
[0079] FIG. 12 is a perspective view of a secondary battery
according to further another embodiment of the present
invention, and FIG. 13 is an exploded perspective view of the
secondary battery according to further another embodiment of
the present invention.
[0080] Referring to FISG. 12 and 13, a secondary battery 300
according to further another embodiment of the present
invention comprises an electrode assembly 310 in which a
first electrode 311, a separator 314, and a second electrode
312 are alternately stacked, a can 320 comprising a first can
321 and a second can 322, which accommodate the electrode
assembly 310 therein, and an insulator 323 insulating an
overlapping portion between the first can 321 and the second
can 322.
[0081] The secondary battery 300 according to further
another embodiment of the present invention is different from
the secondary batteries according to the foregoing
embodiments in a shape of the can 310. Thus, contents of
this embodiment, which are duplicated with those according to
the forgoing embodiment, will be omitted or briefly described,
19
and also, differences therebetween will be mainly described.
[0082] In more detail, in the secondary battery 300
according to further another embodiment of the present
invention, the can 320 may be provided with an accommodation
part that accommodates the electrode assembly 310 therein and
comprise a first can 321 and a second can 322, which have
cylindrical shapes and are opened in a direction facing each
other.
[0083] Here, the first can 321 may be electrically connected
to the first electrode 311, and the second can 322 may be
electrically connected to the second electrode 312.
[0084] Also, each of the first can 321 and the second can
322 may have a rectangular cylindrical shape. The first can
321 may have an inner width greater than an outer width of
the second can 322 so that the second can is inserted into
the first can 321.
[0085] Furthermore, the first can 321 may have one side 321b
in which a first opening (not shown) that is opened in one
direction C1 is formed and the other side 321c at which a
first connection part 321a that is closed in the other
direction C2 is formed. The second can 322 may have the
other side 322c in which a second opening 322d that is opened
in the other direction C2 is formed and one side 322b at
which a second connection part 322a that is closed in the one
direction C1 is formed. At this time, the first electrode
311 may have one end connected to the first connection part
321a, and the second electrode 312 may have one end connected
to the second connection part 322a.
[0086] The insulator 323 may comprise an insulation material
to insulate the overlapping portion between the first can 321
20
and the second can 322.
[0087] Also, a short-circuit induction through-part 323a
that is provided in the form of a through-hole or a cutoff
line may be formed in the insulator 323. Here, the short
circuit occurs between the first can 321 and the second can
322 through the short-circuit induction through-part 323a
that is deformed in shape when the insulator 323 is
contracted or expanded by heat or a pressure.
[0088] In the secondary battery 300 according to further
another embodiment of the present invention, for example, the
first can 321 may comprise steel, and the second can 322 may
comprise aluminum.
[0089] Furthermore, for another example, the first can 321
may comprise aluminum, and the second can 322 may comprise
steel.
[0090] In the secondary battery 300 according to further
another embodiment of the present invention, for example, the
first electrode 311 may be provided as a negative electrode,
and the second electrode 312 may be provided as a positive
electrode.
[0091] Furthermore, for another example, the first electrode
311 may be provided as a positive electrode, and the second
electrode 312 may be provided as a negative electrode.
[0092]
[0093] FIG. 14 is a view illustrating a displacement of a
can in a secondary battery according to Manufacturing Example
1.
[0094] A secondary battery comprising an electrode assembly,
a can in which an accommodation part that accommodates the
electrode assembly therein is formed and which comprises a
21
first can and a second can, which have cylindrical shapes and
are opened in a direction facing each other, and an insulator
in which a short-circuit induction through-part that has a
through-hole and insulates an overlapping portion between the
first can and the second can is formed was manufactured.
[0095] Here, the outer can that is the first can disposed at
the outside was made of steel, and the inner can that is the
second can disposed at the inside was made of aluminum. Here,
the outer can has a thickness of 0.1t (t=1mm), and the inner
can has a thickness of 0.1t.
[0096] Also, the insulator was made of a polymer PP material
and a thickness 0.1t (t=1mm).
[0097] The inner can had an outer diameter of 50 mm.
[0098]
[0099] FIG. 15 is a view illustrating a displacement of a
can in a secondary battery according to Manufacturing Example
2.
[00100] A secondary battery comprising an electrode assembly,
a can in which an accommodation part that accommodates the
electrode assembly therein is formed and which comprises a
first can and a second can, which have cylindrical shapes and
are opened in a direction facing each other, and an insulator
in which a short-circuit induction through-part that has a
through-hole and insulates an overlapping portion between the
first can and the second can is formed was manufactured.
[00101] Here, the outer can that is the first can disposed at
the outside was made of aluminum, and the inner can that is
the second can disposed at the inside was made of steel.
Here, the outer can has a thickness of 0.1t (t=1mm), and the
inner can has a thickness of 0.1t.
22
[00102] Also, the insulator was made of a PP material and a
thickness 0.1t (t=1mm).
[00103] The inner can had an outer diameter of 50 mm.
[00104]
[00105] FIG. 16 is a view illustrating a displacement of a
can in a secondary battery according to Comparative Example 1.
[00106] A secondary battery comprising an electrode assembly,
a can in which an accommodation part that accommodates the
electrode assembly therein is formed and which comprises a
first can and a second can, which have cylindrical shapes and
are opened in a direction facing each other, and an insulator
in which a short-circuit induction through-part that has a
through-hole and insulates an overlapping portion between the
first can and the second can is not formed was manufactured.
[00107] Here, the outer can that is the first can disposed at
the outside was made of steel, and the inner can that is the
second can disposed at the inside was made of aluminum. Here,
the outer can has a thickness of 0.1t (t=1mm), and the inner
can has a thickness of 0.1t.
[00108] Also, the insulator was made of a polymer PP material
and a thickness 0.1t (t=1mm).
[00109] The inner can had an outer diameter of 50 mm.
[00110]
[00111] FIG. 17 is a view illustrating a displacement of a
can in a secondary battery according to Comparative Example 2.
[00112] A secondary battery comprising an electrode assembly,
a can in which an accommodation part that accommodates the
electrode assembly therein is formed and which comprises a
first can and a second can, which have cylindrical shapes and
are opened in a direction facing each other, and an insulator
23
in which a short-circuit induction through-part that
insulates an overlapping portion between the first can and
the second can is not formed was manufactured.
[00113] Here, the outer can that is the first can disposed at
the outside was made of aluminum, and the inner can that is
the second can disposed at the inside was made of steel.
Here, the outer can has a thickness of 0.1t (t=1mm), and the
inner can has a thickness of 0.1t.
[00114] Also, the insulator was made of a polymer PP material
and a thickness 0.1t (t=1mm).
[00115] The inner can had an outer diameter of 50 mm.
[00116]
[00117] A displacement of an inner can due to a pressure
acting to be expanded from the inside to the outside of the
battery was displayed when an internal pressure acting on a
can is 1.5 MPa, both inner and outer cans act in an outward
direction, top and bottom surfaces of the can are subjected
to the same restriction conditions.
[00118] As a result of the experiment, referring to FIG. 14,
it is seen that when the can made of aluminum (Al) according
to Manufacturing Example 1 is located at the inside, a
deformation amount of 0.30865 mm occurs. Referring to FIG.
15, it is seen that when the can made of steel according to
Manufacturing Example 2 is located at the inside, a
deformation amount of 0.08009 mm occurs. That is, it is seen
that when the can made of aluminum (Al) is located at the
inside, the can is more expanded due to an elastic modulus
lower than the can made of steel in comparison to the case
the can is located at the inside. Also, it may be expected
that even plastic deformation occurs to implement sufficient
24
deformation. The large expansion under the same conditions
may mean that the short-circuit induction through-part is
more largely deformed under the same conditions. If the
deformation of the short-circuit induction through-part is
lager, the short circuit between the first can and the second
can may occur more easily. However, when the can made of the
steel material is located at the inside, a process (a pressfitting process) of fitting the inner can into the outer can
may be easy due to physical properties of high rigidity of
the steel.
[00119] Also, referring to FIG. 16, it is seen that when the
can made of aluminum (Al) according to Comparative Example 1
is located at the inside, a deformation amount of 0.09127 mm
occurs. Referring to FIG. 17, it is seen that when the can
made of steel according to Comparative Example 2 is located
at the inside, a deformation amount of 0.03965 mm occurs.
[00120] Therefore, as illustrated in FISG. 14 to 17, when
comparing to Comparative Examples 1 and 2 in which the
insulator having no short-circuit induction through-part
formed in the form of the through-hole is provided between
the outer can and the inner can, it is seen that more
expansion occurs in the can according to Manufacturing
Examples 1 and 2 in which the insulator comprising the shortcircuit induction through-part formed in the form of the
through-hole is provided between the outer can and the inner
can.
[00121] As a result, the large expansion under the same
conditions may mean that the insulator is more largely
deformed under the same conditions. As a result, it is seen
that the deformation of the short-circuit induction through-
25
part largely occurs, and thus, the short circuit between the
first can and the second can easily occurs.
[00122] While the present invention has been particularly
shown and described with reference to exemplary embodiments
thereof, it is to be understood that the scope of the present
invention is not limited to the secondary battery according
to the present invention. It will be understood by those of
ordinary skill in the art that various changes in form and
details may be made therein without departing from the spirit
and scope of the invention.
[00123] Furthermore, the scope of protection of the present
invention will be clarified by the appended claims.

CLAIMS
1. A secondary battery comprising:
an electrode assembly in which a first electrode, a
separator, and a second electrode are alternately stacked to
be wound;
a can in which an accommodation part configured to
accommodate the electrode assembly therein is formed and
which comprises a first can and a second can, which have
cylindrical shapes and are opened in a direction facing each
other; and
an insulator configured to insulate an overlapping
portion between the first can and the second can,
wherein the first can is electrically connected to the
first electrode, and the second can is electrically connected
to the second electrode,
the insulator is provided with a short-circuit
induction through-part having the form of a through-hole or a
cutoff line, and
short circuit occurs between the first can and the
second can through the short-circuit induction through-part
that is deformed in shape as heat or a pressure is applied to
contact or expand the insulator.
2. The secondary battery of claim 1, wherein the
short-circuit induction through-part is provided in plurality.
3. The secondary battery of claim 2, wherein at
least one row or column of the short-circuit induction
through-parts is formed in the insulator.
27
4. The secondary battery of claim 2, wherein the
short-circuit induction through-part having a lattice shape
is formed in the insulator.
5. The secondary battery of claim 1, wherein the
insulator comprises a polymer material.
6. The secondary battery of claim 5, wherein the
polymer material comprises one of PE, PP, and PET.
7. The secondary battery of claim 5, wherein the
polymer material comprises a PE or PP material having a
melting point at a temperature of 180℃ or less.
8. The secondary battery of claim 1, wherein each of
the first can and the second can has a cylindrical shape, and
the first can has an inner circumferential surface
greater than an outer circumferential surface of the second
can so that the second can is inserted into the first can.
9. The secondary battery of claim 8, wherein the
insulator is applied to the outer circumferential surface of
the second can to form a coating layer.
10. The secondary battery of claim 8, wherein the
insulator is attached to the outer circumferential surface of
the second can through any one of painting, printing,
cladding, lamination, spraying, masking, dipping, and bonding.
28
11. The secondary battery of claim 8, wherein the
first can has one side in which a first opening that is
opened in one direction is formed and the other side at which
a first connection part that is closed in the other direction
is formed,
the second can has the other side in which a second
opening that is opened in the other direction is formed and
one side at which a second connection part that is closed in
the one direction is formed, and
the first electrode has one end connected to the first
connection part, and the second electrode has one end
connected to the second connection part.
12. The secondary battery of claim 11, wherein one
end of the insulator extends to be closer to the second
connection part than one end of the first can.
13. The secondary battery of claim 11, wherein the
other end of the insulator extends to be closer to the first
connection part than the other end of the second can.
14. The secondary battery of claim 8, wherein the
first can comprises steel, and the second can comprises
aluminum.
15. The secondary battery of claim 8, wherein the
first can comprises aluminum, and the second can comprises
steel.
16. The secondary battery of claim 14, wherein the
29
first electrode is provided as a negative electrode, and the
second electrode is provided as a positive electrode.
17. The secondary battery of claim 15, wherein the
first electrode is provided as a positive electrode, and the
second electrode is provided as a negative electrode.
18. The secondary battery of claim 1, wherein each of
the first can and the second can has a rectangular
cylindrical shape, and
the first can has an inner width greater than an outer
width of the second can.