【Technical Field】
[1] This application claims the benefit of priority
to Korean Patent Application No. 2020-0157820 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
3
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
4
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
5
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
housing configured to receive a plurality of battery
cells; a battery pack case configured to receive one or
more of battery module housings; a water tank located
above the battery module housings; and a heat sink
located under the battery module housings, wherein at
least a portion of the surface of the battery module
7
housing that faces the water tank is open.
[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 configured to have a
size that covers upper surfaces of all of the battery
module housings.
[30] In the battery pack according to the present
invention, the water tank may be attached to the inside
of an upper surface of the battery pack case.
[31] In the battery pack according to the present
invention, an upper part of the battery pack case may be
open, and the water tank may be coupled to the battery
pack case so as to cover the upper surface of the open
battery pack case.
[32] In the battery pack according to the present
invention, the battery module housing may be formed in
the shape of a plate disposed at each of opposite side
surfaces of a battery cell stack constituted by a
plurality of battery cells.
[33] In the battery pack according to the present
invention, a metal strap configured to fix the plurality
of battery cells may be added to each of an upper
8
surface and a lower surface of the battery cell stack.
[34] In the battery pack according to the present
invention, the battery module housing may be configured
to have a structure that wraps outer surfaces of a
battery cell stack constituted by the plurality of
battery cells excluding opposite ends thereof from which
electrode terminals protrude, and an opening may be
formed in one surface of the battery module housing that
faces the water tank.
[35] 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 battery module housing,
and a sealing member may be added to the through-hole.
[36] 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.
[37] 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
in the water tank may be introduced into the battery
cell through the through-hole.
[38] 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 one
9
surface of the water tank so as to be uniformly
dispersed.
[39] In the battery pack according to the present
invention, a partition wall may be added between the
battery module housings.
[40] 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.
[41] 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.
[42]
【Advantageous Effects】
[43] As is apparent from the above description, a
battery pack according to the present invention has a
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.
10
[44] In addition, a sealing member is added to one
surface of the water tank that faces a battery module
housing. When the sealing member is removed as the
result of melting, it is possible to spray a coolant
toward the ignited battery cell irrespective of the
position or orientation of the battery pack.
[45] In addition, a through-hole is formed in one
surface of the water tank, and the through-hole is filled
with the sealing member, whereby it is possible to
minimize an increase in weight of the battery pack due to
addition of the sealing member.
[46] In addition, even though fire breaks out in any
one of battery cells constituting a battery cell stack,
it is possible to exactly inject the coolant into the
ignited battery cell. Even when the present invention is
applied to a large-capacity battery pack, therefore, it
is possible to obtain a thermal spread interruption
effect.
[47] Also, in the case in which water is used instead
of a fire extinguishing agent, it is possible to reduce
production cost.
[48]
【Description of Drawings】
[49] FIG. 1 is a perspective view of a battery pack
11
according to a first embodiment of the present invention.
[50] FIG. 2 is an exploded perspective view of the
battery pack according to the first embodiment.
[51] FIG. 3 is a perspective view of a battery module
including a battery module housing having an opening
formed in one surface thereof that faces a water tank.
[52] FIG. 4 is a sectional view of the battery pack
taken along line A-A’ of FIG. 1.
[53] FIG. 5 is a schematic view illustrating a
situation in which flames are extinguished when fire
breaks out in the battery pack according to the first
embodiment.
[54] FIG. 6 is an exploded perspective view of a
battery pack according to a second embodiment.
[55] FIG. 7 is a sectional view of the battery pack
taken along line A-A’ of FIG. 6.
[56] FIG. 8 is a schematic view illustrating a
situation in which flames are extinguished when fire
breaks out in the battery pack according to the second
embodiment.
[57] FIG. 9 is an exploded perspective view of a
battery pack according to a third embodiment.
[58] FIG. 10 is a sectional view of the battery pack
taken along line A-A’ of FIG. 9.
[59] FIG. 11 is a schematic view illustrating a
12
situation in which flames are extinguished when fire
breaks out in the battery pack according to the third
embodiment.
[60]
【Best Mode】
[61] Now, preferred embodiments of the present
invention will be described in detail with reference to
the accompanying drawings such that the preferred
embodiments of the present invention can be easily
implemented by a person having ordinary skill in the art
to which the present invention pertains. In describing
the principle of operation of the preferred embodiments
of the present invention in detail, however, a detailed
description of known functions and configurations
incorporated herein will be omitted when the same may
obscure the subject matter of the present invention.
[62] In addition, the same reference numbers will be
used throughout the drawings to refer to parts that
perform similar functions or operations. In the case in
which one part is said to be connected to another part
throughout the specification, not only may the one part
be directly connected to the other part, but also, the
one part may be indirectly connected to the other part
via a further part. In addition, that a certain element
13
is included does not mean that other elements are
excluded, but means that such elements may be further
included unless mentioned otherwise.
[63] In addition, a description to embody elements
through limitation or addition may be applied to all
inventions, unless particularly restricted, and does not
limit a specific invention.
[64] Also, in the description of the invention and the
claims of the present application, singular forms are
intended to include plural forms unless mentioned
otherwise.
[65] Also, in the description of the invention and the
claims of the present application, “or” includes “and”
unless mentioned otherwise. Therefore, “including A or B”
means three cases, namely, the case including A, the case
including B, and the case including A and B.
[66] In addition, all numeric ranges include the
lowest value, the highest value, and all intermediate
values therebetween unless the context clearly indicates
otherwise.
[67] Embodiments of the present invention will be
described in detail with reference to the accompanying
drawings.
[68] FIG. 1 is a perspective view of a battery pack
according to a first embodiment of the present invention,
14
and FIG. 2 is an exploded perspective view of the
battery pack according to the first embodiment.
[69] Referring to FIGS. 1 and 2, the battery pack
according to the present invention includes a battery
module housing 111 configured to receive a plurality of
battery cells 120, a battery pack case 100 configured to
receive one or more battery module housings 111, a water
tank 200 located above the battery module housings 111,
and a heat sink 300 located under the battery module
housings 111, wherein at least a portion of the surface
of the battery module housing 111 that faces the water
tank 200 is open.
[70] A through-hole is formed in the lower surface of
the water tank 200. A sealing member 220 is added to the
through-hole in order to prevent discharge of a coolant
through the through-hole when the battery pack is in a
normal state. Since the sealing member 220 is added to
the lower surface of the water tank, the sealing member
is not visible from outside of the battery pack. For the
convenience of description, however, the sealing member
220 is shown in FIGS. 1 and 2.
[71] In a concrete example, each of the plurality of
battery cells 120 may be a pouch-shaped battery cell, and
the bottoms of electrode assembly receiving portions are
disposed so as to be perpendicular to the ground in the
15
state in which the pouch-shaped battery cells are stacked
such that the electrode assembly receiving portions are
in tight contact with each other.
[72] The pouch-shaped battery cell may be a
bidirectional battery cell having a positive electrode
lead and a negative electrode lead protruding in opposite
directions or a unidirectional battery cell having a
positive electrode lead and a negative electrode lead
protruding in the same direction.
[73] A flow path 310 configured to guide flow of the
coolant introduced into and discharged from the heat
sink is formed in the heat sink 300, and the temperature
of the coolant introduced into and discharged from the
heat sink 300 may be maintained at a predetermined level.
Even though heat is generated in the battery cell 120
due to repeated charging and discharging of a lithium
secondary battery, therefore, it is possible to inhibit
an increase in overall temperature of the battery pack.
[74] The water tank 200 is formed in a rectangular
parallelepiped shape in which the lower surface of the
water tank that faces the battery module housings 111
and the upper surface of the water tank, which is
opposite the lower surface, are wide, and the area of
each of the upper surface and the lower surface has a
size that covers the upper surfaces of all of the
16
plurality of battery module housings 111 received in the
battery pack case 100.
[75] In a concrete example, the battery pack case 100
may be a rectangular parallelepiped box from which an
upper surface is removed such that an upper part of the
battery pack case is open, and the water tank 200 may be
coupled to the battery pack case 100 so as to cover the
open upper surface of the battery pack case 100.
[76] That is, the water tank 200 is disposed at the
upper surfaces of the battery module housings 111, and
therefore the water tank may serve as a cover of the
battery pack case having the open upper surface.
[77] In another concrete example, the battery pack
case 100 may be a structure including a rectangular
parallelepiped case body from which an upper surface is
removed such that an upper part of the battery pack case
is open and a top plate coupled to the open upper surface.
At this time, the water tank 200 may be coupled to the
top plate. That is, the water tank 200 may be attached
to an inner surface of the top plate.
[78] Alternatively, the top plate may be the upper
surface of the water tank, and the water tank may be
integrated with the top plate.
[79] The battery module housing 111 shown in FIG. 2
is formed in the shape of a plate disposed at each of
17
opposite side surfaces of a battery cell stack
constituted by a plurality of battery cells 120.
[80] In addition, a metal strap 140 configured to fix
the plurality of battery cells 120 is added to each of
the upper surface and the lower surface of the battery
cell stack.
[81] For example, two or more metal straps 140 may be
added to each battery cell stack, and the metal strap
140 may be added to each of the upper surface and the
lower surface of the battery cell stack in the state in
which the plate-shaped battery module housing 111 is
attached to the opposite side surfaces of the battery
cell stack.
[82] The metal strap 140 added to the upper surface
of the battery cell stack may include an extension
portion extending downwards along the opposite side
surfaces of the battery cell stack, and the metal strap
140 added to the lower surface of the battery cell stack
may include an extension portion extending upwards along
the opposite side surfaces of the battery cell stack.
It is possible to fix the battery cell stack using the
metal straps each including the extension portion such
that the shape of the battery cell stack is maintained.
[83] In addition, the battery cells 120 are exposed
through the portion of the upper surface of the battery
18
cell stack to which the metal strap 140 is not added,
and therefore the coolant may be directly introduced
into the battery cells when the coolant is sprayed from
the water tank 200.
[84] During repeated charging and discharging of the
battery cell 120, the electrode assembly is expanded and
contracted, and gas is generated as a byproduct of
charging and discharging. As a result, the battery
module housing may swell. A partition wall 101 may be
added between one battery module housing 111 and another
battery module housing 111 in order to minimize the
effect of swelling of one battery module housing 111 on
battery module housings adjacent thereto and to fix and
support the battery module housings 111.
[85] FIG. 3 is a perspective view of a battery module
housing having an opening formed in one surface thereof
that faces the water tank.
[86] Referring to FIG. 3, the battery module housing
110 is configured to have a structure that wraps outer
surfaces of a battery cell stack constituted by a
plurality of battery cells 120 excluding opposite ends
thereof from which electrode terminals 121 protrude, and
an opening 130 is formed in one surface of the battery
module housing 110 that faces the water tank.
[87] The shape, size, and number of openings are not
19
particularly restricted as long as a coolant can be
directly injected into all of the battery cells mounted
in the battery module housing 110 through the openings
130 formed in the battery module housing.
[88] The battery cell shown in FIG. 3 is a pouchshaped battery cell, wherein the pouch-shaped battery
cell may be a bidirectional battery cell having a
positive electrode lead and a negative electrode lead
protruding in opposite directions or a unidirectional
battery cell having a positive electrode lead and a
negative electrode lead protruding in the same direction.
[89] FIG. 4 is a sectional view of the battery pack
taken along line A-A’ of FIG. 1, and FIG. 5 is a
schematic view illustrating a situation in which flames
are extinguished when fire breaks out in the battery
pack according to the first embodiment.
[90] Referring to FIGS. 4 and 5, the plate-shaped
battery module housings 111 shown in FIG. 2 are used as
battery module housings, and no metal straps are shown
in the section for the convenience of description.
[91] A plurality of battery module housings 111 is
disposed in the battery pack case 100, and a plurality
of battery cells 120 is disposed in each battery module
housing 111. The water tank 200 is disposed above the
plurality of battery module housings 111, and the
20
interior of the water tank 200 is filled with a coolant
configured to lower the temperature of a heated or
ignited battery cell.
[92] A through-hole is formed in one surface of the
water tank 200 that faces the battery module housings
111, and a sealing member 220 is added to the throughhole in order to hermetically seal the through-hole.
The sealing member 220 is made of a material that is
melted by high-temperature gas or sparks discharged from
the battery cell 120. That is, when the battery cell
120 is in a normal state, the state in which the
through-hole is hermetically sealed by the sealing
member 220 is maintained. However, when the temperature
of an ignited battery cell, e.g. a battery cell 120’, is
increased and flames are generated and spread to a
sealing member located adjacent thereto, the sealing
member 220, which has a low melting point, is melted,
whereby the through-hole 230 is opened. Consequently,
the coolant in the water tank 200 may be directly
introduced into the battery cell.
[93] The coolant received in the water tank 200 is
evaporated by fire outbreak in the battery cell, whereby
the volume of the coolant is increased and thus the
coolant is transformed into a high pressure state. When
the through-hole 230 is opened, therefore, the coolant
21
may be sprayed toward the ignited battery cell at a high
pressure.

【CLAIMS】
【Claim 1】 A battery pack comprising:
a battery module housing configured to receive a
plurality of battery cells;
a battery pack case configured to receive one or
more of the battery module housings;
a water tank located above the battery module
housings; and
a heat sink located under the battery module
housings, wherein
at least a portion of a surface of the battery
module housing that faces the water tank is open.
【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 configured to have a size that
covers upper surfaces of all of the battery module
housings.
【Claim 4】 The battery pack according to claim 1,
31
wherein the water tank is attached to an inside of an
upper surface of the battery pack case.
【Claim 5】 The battery pack according to claim 1,
wherein an upper part of the battery pack case is open,
and
wherein the water tank is coupled to the battery
pack case so as to cover the upper surface of the open
battery pack case.
【Claim 6】 The battery pack according to claim 1,
wherein the battery module housing is formed in a shape
of a plate disposed at each of opposite side surfaces of
a battery cell stack constituted by a plurality of
battery cells.
【Claim 7】 The battery pack according to claim 6,
wherein a metal strap configured to fix the plurality of
battery cells is added to each of an upper surface and a
lower surface of the battery cell stack.
【Claim 8】 The battery pack according to claim 1,
wherein the battery module housing is configured to have
a structure that wraps outer surfaces of a battery cell
stack constituted by the plurality of battery cells
32
excluding opposite ends thereof from which electrode
terminals protrude, and
wherein an opening is formed in one surface of the
battery module housing that faces the water tank.
【Claim 9】 The battery pack according to claim 1,
wherein a through-hole is formed in one surface of the
water tank that faces the battery module housing, and
wherein a sealing member is added to the throughhole.
【Claim 10】 The battery pack according to claim 9,
wherein the sealing member is made of a material that is
melted by high-temperature gas or sparks discharged from
the battery cell.
【Claim 11】 The battery pack according to claim 10,
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 12】 The battery pack according to claim 9,
wherein the through-hole is configured to have a
33
structure in which a plurality of holes is formed in the
one surface of the water tank so as to be uniformly
dispersed.
【Claim 13】 The battery pack according to claim 1,
wherein a partition wall is added between the battery
module housings.
【Claim 14】 The battery pack according to claim 9,
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 15】 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.