TECHNICAL FIELD
[0002] The present invention relates to a cylindrical type
secondary battery, and more particularly, to a cylindrical
type secondary battery in which, when a center pin is
15 inserted into a core of an electrode assembly, and a cap
assembly is coupled to an upper portion of a battery case,
the inserted center pin supports the electrode assembly in a
radial direction on an inner circumferential surface of the
core by elasticity to prevent collapse of the core and
20 increase in adhesion force of positive and negative
electrodes.
BACKGROUND ART
[0003] In general, secondary batteries refer to batteries
that are chargeable and dischargeable unlike non-rechargeable
25 primary batteries and have been widely used as power sources
3
of electronic devices such as cellular phones, notebook
computers and camcorders, electric vehicles or the like.
[0004] According to the shape of a battery case, such
secondary batteries may be classified into a cylindrical type
5 battery and a square type battery in each of which an
electrode assembly is embedded in a metal can having a
cylindrical or a square shape, a pouch type battery in which
an electrode assembly is embedded in a pouch-shaped case made
of an aluminum laminate sheet, and so on.
10 [0005] A cylindrical type battery commonly includes an
electrode assembly constituted by a positive electrode, a
negative electrode and a separator, a can that accommodates
the electrode assembly and is provided with an opening in an
upper end thereof, and a cap assembly that finishes the
15 opening in the upper end of the can. The positive electrode
of the electrode assembly is connected to a positive
electrode tab, and the positive electrode tab is connected to
the cap assembly on the upper end of the opening by welding.
The negative electrode of the electrode assembly is connected
20 to a negative electrode tab, and the negative electrode tab
is connected to a bottom surface of the can by welding.
[0006] Generally, the electrode assembly is formed in a
jelly-roll shape by stacking the positive electrode, the
separator and the negative electrode and winding the positive
25 electrode, the separator and the negative electrode, which
4
are stacked, in the form of a roll, and then is accommodated
in the can. A core, a central-most portion of the electrode
assembly wound in the jelly-roll shape, has a hollow
structure irrespective of an outer diameter thereof. However,
5 since such a hollow structure is at high risk of collapsing
by deterioration of the electrode assembly, there are
problems that safety of the battery is hard to achieve and
performance degradation of the battery is concerned.
[0007] In order to solve these problems, a cylindrical type
10 secondary battery 100 having a center pin 200 inserted
thereinto, as illustrated in FIG. 1, has been developed. The
cylindrical type secondary battery 100 illustrated in FIG. 1
exhibits the excellent mechanical strength by inserting the
center pin 200 into a wound electrode assembly, and prevents
15 an internal short circuit by avoiding a distal end of the
center pin 200 being in contact with the electrode assembly
even when the center pin 200 is modified by an external
impact. However, even though the center pin 200 is inserted,
there is a problem that an adhesion force of the electrode
20 assembly is still not high, and also the rate of an electrode
reaction is not relatively high. Accordingly, there is a
need to develop a cylindrical type secondary battery for
improving output of the battery.
DISCLOSURE OF THE INVENTION
25 TECHNICAL PROBLEM
5
[0008] An object of the present invention devised to solve
the problems as above is to provide a cylindrical type
secondary battery in which a center pin is inserted into a
core of an electrode assembly and a cap assembly is coupled
5 to an upper portion of a battery case so that the inserted
center pin may support the electrode assembly in a radial
direction on an inner circumferential surface of the core by
elasticity, thereby preventing collapse of the core and
increasing an adhesion force of positive and negative
10 electrodes, and also the center pin may function as a
separate positive electrode tab or negative electrode tab as
necessary, thereby reducing resistance.
TECHNICAL SOLUTION
[0009] A cylindrical type secondary battery according to the
15 present invention includes a jelly-roll-type electrode
assembly wound by interposing a separator between sheetshaped positive and negative electrodes; a battery case in
which the electrode assembly is accommodated; a cap assembly
coupled to an upper portion of the battery case; and a center
20 pin inserted into a core of the electrode assembly and
configured to support the electrode assembly in a radial
direction on an inner circumferential surface of the core by
elasticity. The center pin includes an elastic body having a
length.
25 [0010] The center pin may further include a lower support
6
which is coupled to one end of the elastic body and in
contact with a lower portion of the battery case.
[0011] The center pin may further include an upper support
which is coupled to the other end of the elastic body and in
5 contact with the cap assembly.
[0012] The center pin may further include a tubular body
which is provided between the lower support and the upper
support and in which a hollow is formed to have the elastic
body provided therein.
10 [0013] The body may have an axial length shorter than the
length of the elastic body.
[0014] A cutoff part taken along an axial direction may be
formed in the body.
[0015] The body may be finished in a shape where an end,
15 formed in the cutoff part, of the body is rolled toward the
inside of the hollow.
[0016] The elastic body may be curved in a positive radial
direction by axial compressive stress acting on the lower
support and the upper support to press the body.
20 [0017] Each of the body, the lower support, the upper
support and the elastic body may be a nonconductor.
[0018] The upper support may be a conductor, the lower
support may be a nonconductor, and the elastic body may be a
conductor.
25 [0019] A first positive electrode non-coating portion may be
7
formed at a winding start portion of the sheet-shaped
positive electrode, wherein one end of the first positive
electrode non-coating portion may be longer than one end of
the separator and protrude toward the inside of the core of
5 the electrode assembly. The elastic body may be provided to
be bonded to the first positive electrode non-coating portion
protruding toward the core of the electrode assembly.
[0020] The upper support may be a conductor, the lower
support may be a nonconductor, and each of the elastic body
10 and the body may be a conductor.
[0021] A first positive electrode non-coating portion may be
formed at a winding start portion of the sheet-shaped
positive electrode, wherein one end of the first positive
electrode non-coating portion may be longer than one end of
15 the separator and protrude toward the inside of the core of
the electrode assembly. The body may be provided to be
bonded to the first positive electrode non-coating portion
protruding toward the core of the electrode assembly.
[0022] A second positive electrode non-coating portion, and
20 a positive electrode tab protruding from the second positive
electrode non-coating portion, may be further formed at a
central portion of the sheet-shaped positive electrode,
wherein the positive electrode tab may be bonded to the upper
support.

CLAIMS
1. A cylindrical type secondary battery comprising:
a jelly-roll-type electrode assembly wound by
5 interposing a separator between sheet-shaped positive and
negative electrodes;
a battery case in which the electrode assembly is
accommodated;
a cap assembly coupled to an upper portion of the
10 battery case; and
a center pin inserted into a core of the electrode
assembly and configured to support the electrode assembly in
a radial direction on an inner circumferential surface of the
core by elasticity,
15 wherein the center pin comprises an elastic body having
a length.
2. The cylindrical type secondary battery of claim 1,
wherein the center pin further comprises a lower support
20 which is coupled to one end of the elastic body and in
contact with a lower portion of the battery case.
3. The cylindrical type secondary battery of claim 2,
wherein the center pin further comprises an upper support
25 which is coupled to the other end of the elastic body and in
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contact with the cap assembly.
4. The cylindrical type secondary battery of claim 3,
wherein the center pin further comprises a tubular body which
5 is provided between the lower support and the upper support
and in which a hollow is formed to have the elastic body
provided therein.
5. The cylindrical type secondary battery of claim 4,
10 wherein the body has an axial length shorter than the length
of the elastic body.
6. The cylindrical type secondary battery of claim 4,
wherein a cutoff part taken along an axial direction is
15 formed in the body.
7. The cylindrical type secondary battery of claim 6,
wherein the body is finished in a shape where an end, formed
in the cutoff part, of the body is rolled toward the inside
20 of the hollow.
8. The cylindrical type secondary battery of claim 4,
wherein the elastic body is curved in a positive radial
direction by axial compressive stress acting on the lower
25 support and the upper support to press the body.
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9. The cylindrical type secondary battery of claim 4,
wherein each of the body, the lower support, the upper
support and the elastic body is a nonconductor.
5
10. The cylindrical type secondary battery of claim 3,
wherein the upper support is a conductor, the lower support
is a nonconductor, and the elastic body is a conductor.
10 11. The cylindrical type secondary battery of claim
10, wherein a first positive electrode non-coating portion is
formed at a winding start portion of the sheet-shaped
positive electrode, wherein one end of the first positive
electrode non-coating portion is longer than one end of the
15 separator and protrudes toward the inside of the core of the
electrode assembly, and
the elastic body is provided to be bonded to the first
positive electrode non-coating portion protruding toward the
core of the electrode assembly.
20
12. The cylindrical type secondary battery of claim 4,
wherein the upper support is a conductor, the lower support
is a nonconductor, and each of the elastic body and the body
is a conductor.
25
34
13. The cylindrical type secondary battery of claim
12, wherein a first positive electrode non-coating portion is
formed at a winding start portion of the sheet-shaped
positive electrode, wherein one end of the first positive
5 electrode non-coating portion is longer than one end of the
separator and protrudes toward the inside of the core of the
electrode assembly, and
the body is provided to be bonded to the first positive
electrode non-coating portion protruding toward the core of
10 the electrode assembly.
14. The cylindrical type secondary battery of claim
10 or 12, wherein a second positive electrode non-coating
portion and a positive electrode tab protruding from the
15 second positive electrode non-coating portion are further
formed at a central portion of the sheet-shaped positive
electrode, wherein the positive electrode tab is bonded to
the upper support.
20 15. The cylindrical type secondary battery of claim
14, wherein the positive electrode tab is bonded to a top
surface of the upper support.
16. The cylindrical type secondary battery of claim
25 11 or 13, wherein an insulating tape is attached to a portion,
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not protruding toward the inside of the core of the electrode
assembly, of the first positive electrode non-coating portion.
17. The cylindrical type secondary battery of claim 3,
5 wherein the upper support is a nonconductor, the lower
support is a conductor, and the elastic body is a conductor.
18. The cylindrical type secondary battery of claim
17, wherein a first negative electrode non-coating portion is
10 formed at a winding start portion of the sheet-shaped
negative electrode, wherein one end of the first negative
electrode non-coating portion is longer than one end of the
separator and protrudes toward the inside of the core of the
electrode assembly, and
15 the elastic body is provided to be bonded to the first
negative electrode non-coating portion protruding toward the
core of the electrode assembly.
19. The cylindrical type secondary battery of claim 4,
20 wherein the upper support is a nonconductor, the lower
support is a conductor, and the elastic body and the body are
conductors.
20. The cylindrical type secondary battery of claim
25 19, wherein a first negative electrode non-coating portion is
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formed at winding start portion of the sheet-shaped negative
electrode, wherein one end of the first negative electrode
non-coating portion is longer than one end of the separator
and protrudes toward the inside of the core of the electrode
5 assembly, and
the body is provided to be bonded to the first negative
electrode non-coating portion protruding toward the core of
the electrode assembly.
10 21. The cylindrical type secondary battery of claim
17 or 19, wherein a second negative electrode non-coating
portion, and a negative electrode tab protruding from the
second negative electrode non-coating portion, are further
formed at a winding end of the sheet-shaped negative
15 electrode, wherein the negative electrode tab is bonded to
the lower support.
22. The cylindrical type secondary battery of claim
18 or 20, wherein an insulating tape is attached to a portion,
20 not protruding toward the inside of the core of the electrode
assembly, of the first negative electrode non-coating portion.
23. The cylindrical type secondary battery of claim 1,
wherein the elastic body has one of a cylindrical shape, a
25 plate shape or a ring shape.
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24. The cylindrical type secondary battery of claim 3,
wherein a horizontal cross-sectional area of the upper
support is larger than a horizontal cross-sectional area of
5 the core of the electrode assembly.
25. The cylindrical type secondary battery of claim 3,
wherein a diameter of the upper support is larger than a
diameter of the core of the electrode assembly.