【Technical Field】
[1] This application claims the benefit of priority
to Korean Patent Application No. 2020-0157821 filed on
November 23, 2020, the disclosure of which is
incorporated herein by reference in its entirety.
[2] The present invention relates to a battery pack
including a thermal spread inhibition structure. More
particularly, the present invention relates to a battery
pack including a thermal spread inhibition structure
capable of directly injecting a coolant into an ignited
battery cell in order to prevent spread of flames of the
ignited battery cell in the battery pack.
[3]
【Background Art】
[4] As the result of continuous research and
development of a lithium secondary battery, it has been
possible to manufacture and commercialize a lithium
secondary battery having increased capacity and improved
output. In addition, demand for the lithium secondary
2
battery as an energy source replaceable fossil fuels,
which cause environmental pollution, has increased.
[5] Accordingly, application of the lithium secondary
battery to various devices has increased. For example,
the lithium secondary battery has been widely used as an
energy source for wireless mobile devices, which are
small multifunctional products, and wearable devices,
which are worn on the body, and has also been used as an
energy source for electric vehicles and hybrid electric
vehicles presented as alternatives to existing gasoline
and diesel vehicles or as an energy storage system (ESS).
[6] As the lithium secondary battery is used as a
large-capacity, high-output energy source, as described
above, securing safety of the lithium secondary battery
becomes an important subject of interest.
[7] Generally, in the case in which fire breaks out
in a battery cell received in the energy storage system,
a method of injecting water into a battery module or a
battery pack through a separate watering device is used.
[8] In this case, however, facilities and space for
the watering device are required, and the fire may spread
due to a time difference between sensing time of gas
discharged due to venting of the battery cell and
watering time.
[9] Alternatively, a method of disposing an
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insulating material or a fire extinguishing agent inside
or outside the battery module or the battery pack in
order to interrupt heat transfer between battery cells or
to cool the ignited battery cell may be used.
[10] In the case in which the insulating material is
used, however, a fire extinguishing function is not
performed although propagation of flames is interrupted.
In the case in which the fire extinguishing agent is used,
the fire extinguishing agent is not exactly spread to the
point at which fire breaks out, since the fire
extinguishing agent is disposed in an empty space in the
battery pack in consideration of energy density.
[11] As technology for preventing thermal runaway of
the battery pack, Patent Document 1 discloses an
apparatus configured such that a bag containing water is
located above a battery, the bag is made of a material
that has a relatively low melting point, and when the
temperature of the battery is increased, the bag is
melted and the water in the bag is discharged to the
battery.
[12] In Patent Document 1, the entirety of the bag is
made of material that has a low melting point. When the
temperature of the battery is increased, therefore, the
water is not discharged from a specific portion of the
bag but the entirety of the water in the bag is
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discharged while the bag is melted.
[13] In the case in which the bag is disposed so as to
be located under the battery cell, therefore, the water
cannot be injected into the battery cell, whereby it is
not possible to exhibit a fire extinguishing function.
Consequently, there is a limitation in that the bag must
be used only in a specific direction such that the bag is
disposed above the battery cell.
[14] Patent Document 2 is configured such that a
middle case and an inner case are received in an outer
case, a plurality of cells is received in the middle case,
a fire extinguishing agent is received in the inner case,
and when the cells generate heat to an upper limit
temperature or higher, the fire extinguishing agent is
introduced into the middle case through an injection pipe.
When the cells generate heat to an upper limit
temperature or higher, the injection pipe is opened,
whereby the fire extinguishing agent received in the
inner case is injected into the middle case.
[15] In Patent Document 2, compressed gas for spraying
the fire extinguishing agent, a nozzle used as the
injection pipe, and the inner case configured to receive
the fire extinguishing agent are included, whereby an
additional space therefor is necessary, and expense
necessary to purchase the fire extinguishing agent and
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the compressed gas is also further incurred.
[16] Patent Document 3 discloses a battery module
including a cell assembly, a heat sink located so as to
abut the outer surface of the cell assembly, the heat
sink having formed therein a refrigerant flow path, along
which a refrigerant flows, and a thermally shrinkable
tube thermally shrunk such that the cell assembly and the
heat sink come into tight contact with each other.
[17] In Patent Document 3, the heat sink and the cell
assembly are disposed in tight contact with each other,
whereby it is possible to obtain a cell assembly heat
dissipation effect; however, it is not possible to
exhibit a function of preventing spread of flames between
adjacent battery modules when fire breaks out in the cell
assembly.
[18] Therefore, there is a high necessary for
technology capable of minimizing spread of flames and
preventing a decrease in energy density without needing
an additional space when fire breaks out in a battery
cell received in a battery pack.
[19]
[20] (Prior Art Documents)
[21] (Patent Document 1) Japanese Patent Application
Publication No. 2014-523622 (2014.09.11)
[22] (Patent Document 2) Japanese Patent Application
6
Publication No. 2012-252909 (2012.12.20)
[23] (Patent Document 3) Korean Patent Application
Publication No. 2020-0030964 (2020.03.23)
[24]
【Disclosure】
【Technical Problem】
[25] The present invention has been made in view of
the above problems, and it is an object of the present
invention to provide a battery pack including a fire
extinguishing and thermal spread inhibition structure
capable of extinguishing ignition of a battery cell when
the battery cell catches fire or explodes and preventing
spread of flames to battery cells adjacent thereto.
[26]
【Technical Solution】
[27] A battery pack according to the present invention
to accomplish the above object includes a battery module
configured to receive a plurality of battery cells; a
battery pack case configured to receive two or more
battery modules, and a heat sink located under the
battery modules, wherein each of the battery modules
includes a plurality of battery cells; a water tank
located above the plurality of battery cells, and a
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module case configured to receive the plurality of
battery cells and the water tank.
[28] In the battery pack according to the present
invention, a flow path configured to guide flow of a
coolant introduced into and discharged from the heat
sink may be formed in the heat sink.
[29] In the battery pack according to the present
invention, the water tank may be mounted integrally to
the inside of an upper surface of the module case.
[30] In the battery pack according to the present
invention, an upper part of the module case may be open,
and the water tank may be coupled to the module case so
as to cover the upper surface of the open module case.
[31] In the battery pack according to the present
invention, a through-hole may be formed in one surface
of the water tank that faces the plurality of battery
cells, and a sealing member may be added to the throughhole.
[32] In the battery pack according to the present
invention, the sealing member may be made of a material
that is melted by high-temperature gas or sparks
discharged from the battery cell.
[33] In the battery pack according to the present
invention, the through-hole may be opened as the result
of melting of the sealing member, and a coolant received
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in the water tank may be introduced into the battery
cell through the through-hole.
[34] In the battery pack according to the present
invention, the through-hole may be configured to have a
structure in which a plurality of holes is formed in the
one surface of the water tank so as to be uniformly
dispersed.
[35] In the battery pack according to the present
invention, a partition wall may be added between the
module cases.
[36] In the battery pack according to the present
invention, the through-hole may be filled with the
sealing member, and the sealing member may include an
extension portion further extending outwards from an
outer surface of the water tank than the circumference
of the through-hole.
[37] In the battery pack according to the present
invention, each of the battery cells may be a pouchshaped battery cell, a prismatic battery cell, or a
cylindrical battery cell.
[38]
【Advantageous Effects】
[39] As is apparent from the above description, a
battery pack according to the present invention has a
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water tank disposed therein, whereby it is possible to
rapidly cool an ignited battery cell without increasing
the external size of the battery pack, and therefore it
is possible to securely inhibit a thermal runaway
phenomenon of the battery cell.

【Claim 1】 A battery pack comprising:
a battery module configured to receive a plurality
of battery cells;
a battery pack case configured to receive two or
more of the battery modules; and
a heat sink located under the battery modules,
wherein each of the battery modules comprises:
a plurality of battery cells;
a water tank located above the plurality of
battery cells; and
a module case configured to receive the
plurality of battery cells and the water tank.
【Claim 2】 The battery pack according to claim 1,
wherein a flow path configured to guide flow of a
coolant introduced into and discharged from the heat
sink is formed in the heat sink.
【Claim 3】 The battery pack according to claim 1,
wherein the water tank is mounted integrally to an
inside of an upper surface of the module case.
【Claim 4】 The battery pack according to claim 1,
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wherein an upper part of the module case is open, and
wherein the water tank is coupled to the module case
so as to cover the upper surface of the open module case.
【Claim 5】 The battery pack according to claim 1,
wherein a through-hole is formed in one surface of the
water tank that faces the plurality of battery cells, and
wherein a sealing member is added to the throughhole.
【Claim 6】 The battery pack according to claim 5,
wherein the sealing member is made of a material that is
melted by high-temperature gas or sparks discharged from
the battery cell.
【Claim 7】 The battery pack according to claim 6,
wherein the through-hole is opened as a result of
melting of the sealing member, and
wherein a coolant received in the water tank is
introduced into the battery cell through the throughhole.
【Claim 8】 The battery pack according to claim 5,
wherein the through-hole is configured to have a
structure in which a plurality of holes is formed in the
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one surface of the water tank so as to be uniformly
dispersed.
【Claim 9】 The battery pack according to claim 1,
wherein a partition wall is added between the module
cases.
【Claim 10】 The battery pack according to claim 1,
wherein the through-hole is filled with the sealing
member, and
wherein the sealing member comprises an extension
portion further extending outwards from an outer surface
of the water tank than a circumference of the throughhole.
【Claim 11】 The battery pack according to claim 1,
wherein each of the battery cells is a pouch-shaped
battery cell, a prismatic battery cell, or a cylindrical
battery cell.