Patent Description:
Currently, commercialized secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium secondary batteries, etc. Among these batteries, lithium secondary batteries are in the limelight because the lithium secondary batteries have almost no memory effect compared with nickel-based secondary batteries and thus charging/discharging is freely performed, a self-discharge rate is very low, and energy density is high.

The lithium secondary battery primarily uses a lithium-based oxide and a carbon material as an anode active material and a cathode active material, respectively. The lithium secondary battery includes an electrode assembly in which an anode plate and a cathode plate coated with the anode active material and the cathode material, respectively, are arranged with a separator therebetween, and an exterior material sealing the electrode assembly and an electrolyte together.

Generally, lithium secondary batteries may be classified into can-type secondary batteries in which an electrode assembly is mounted within a metallic can, and pouch-type secondary batteries in which an electrode assembly is mounted within a pouch including an aluminum laminated sheet depending on the shape of an exterior material.

Recently, secondary batteries are widely used for medium and large apparatuses such as automobiles or power storing apparatuses as well as small apparatuses such as portable electronic apparatuses. In the case where the secondary batteries are used for medium and large apparatuses, lots of secondary batteries are electrically connected in order to increase capacity and power. Particularly, pouch-type secondary batteries are widely used for the medium and large apparatuses due to an advantage of easy stacking. Also, a plurality of secondary batteries may be stored in a pack case to configure one battery pack.

The battery pack requires various characteristics. Safety is a representative characteristic among the characteristics. Furthermore, since it is considered that safety of the battery pack mounted on an automobile is directly linked to life of a passenger, the safety of the battery pack is very important.

Particularly, one of important issues relating to the safety of the battery pack is direct exposure to a flame. In the case of the battery pack, although preventing fire from occurring in the inside of the battery pack is a first priority, fire may occur in the inside of the battery pack depending on cases. In this case, when a flame or a high temperature gas is exposed much to the outside of the battery pack, the exposed flame or high temperature gas may destroy or damage other elements in the vicinity of the battery pack and cause secondary fire. Particularly, when fire occurs in the inside of the mounted battery pack, the occurred fire may be very dangerous for a passenger. Furthermore, in the case where the battery pack is mounted on a hybrid automobile or collides with another automobile, when fire or a high temperature gas is exposed to a fuel storing tank, explosion of fuel may be caused and thus a big accident may be generated.

Also, another of important issues relating to the safety of the battery pack is impact resistance. That is, it is preferable that internal elements of the battery pack are not easily destroyed even by an impact of a preset level or more and maintain their performance. Particularly, since a battery pack for an automobile is always exposed to a danger of automobile collision, a characteristic that internal elements of the battery pack are not easily destroyed from an accident is required even more.

<CIT> discloses a battery pack fixed to a framework built by frame bodies each having a hollow structure.

The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a battery pack which may secure safety when fire or gas occurs therein or an external impact is applied thereto, and an automobile including the battery pack.

Also, it will be easily understood that the objects and advantages of the present disclosure may be realized by the means shown in the appended claims.

In one aspect of the present disclosure, there is provided a battery pack including: a cell assembly including a plurality of secondary batteries; and a pack case including a bottom part having a plate shape and located under the cell assembly, and a side wall part protruding from the bottom part to a preset height, the pack case accommodating the cell assembly in an inner space defined by the bottom part and the side wall part, wherein the side wall part of the pack case includes a hollow in a direction at least partially perpendicular to a thickness direction of the side wall part, and the hollow includes an inwardly open inlet and an outwardly open outlet.

The hollow may be provided long in a peripheral direction of the bottom part.

The hollow may be provided as two or more hollows in the side wall part.

The two or more hollows may be vertically arranged in the side wall part, a vertical through part may be provided between the two or more hollows, and the inlet and the outlet may be provided in different hollows, respectively.

In the pack case, the inlet and the outlet may be provided at an end part of one side of the two or more hollows, and the through part may be provided at an end part of another side of the two or more hollows.

The pack case includes two or more inlets and two or more outlets.

The side wall part may include a first side wall including the hollow and a second side wall not including the hollow.

The first side wall may be arranged in a peripheral direction of the bottom part with respect to the second side wall and opposite ends of the first side wall may be coupled to the second side wall.

The hollow may be provided vertically long.

The pack case may include a metallic material.

In another aspect of the present disclosure, there is also provided an automobile including the battery pack according to the present disclosure.

According to the present disclosure, safety of a battery pack may be improved.

Particularly, in one aspect of the present disclosure, even when fire occurs in the inside of a battery pack, direct exposure of the fire or high temperature gas to the outside of the battery pack may be prevented or effectively reduced.

Therefore, according to this aspect of the present disclosure, loss of lives and property loss due to fire of a battery pack may be minimized and secondary fire or explosion, etc. may be prevented.

Furthermore, these effects of the present disclosure may be accomplished by a pack case, and a separate additional part or space, etc. for accomplishing these effects is not required or may be minimized.

Also, in another aspect of the present disclosure, even when an impact is applied from the outside of the battery pack, the pack case may relieve the impact.

Therefore, according to this aspect of the present disclosure, even when an automobile mounting the battery pack therein collides with another automobile or a building, destruction or damage of internal elements of the battery pack may be prevented or reduced. Therefore, in this case, even when a traffic accident occurs, an operation of the battery pack may be guaranteed, a reuse rate may be raised, and a danger such as ignition or explosion, etc. due to an accident may be reduced.

The accompanying drawings illustrate a preferred embodiment of the present disclosure and together with the foregoing disclosure, serve to provide further understanding of the present disclosure, and thus, the present disclosure is not construed as being limited to the drawing.

Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the disclosure, so it should be understood that other equivalents and modifications could be made thereto without departing from the scope of the invention as defined by the appended claims.

<FIG> is a perspective view schematically illustrating a configuration of a battery pack according to an embodiment of the present disclosure.

Referring to <FIG>, the battery pack according to the present disclosure includes a cell assembly <NUM> and a pack case <NUM>.

The cell assembly <NUM> may include a secondary battery. Here, the secondary battery may be a pouch-type secondary battery, but the present disclosure is not limited thereto.

The secondary battery may include an electrode assembly, an electrolyte, and an exterior material. Here, the electrode assembly is an assembly including an electrode and a separation layer and may be configured in a form in which one or more anode plates and one or more cathode plates are arranged with the separation layer therebetween. Also, an electrode tap may be provided to each electrode plate of the electrode assembly and connected to an electrode lead. Particularly, in the case of a pouch-type secondary battery, one or more electrode taps may be connected to the electrode lead, the electrode lead may be arranged between pouch exterior materials, one end thereof may be exposed to outside, and thus function as an electrode terminal. The exterior material may have an empty space therein to accommodate the electrode assembly and the electrolyte and may be provided in a sealed form. The exterior material may include a metallic material in the case of a can-type secondary battery, and in the case of a pouch-type secondary battery, may be configured in a form including an external insulating layer, a metallic layer, and an inner adhesive layer.

Since the configuration of the secondary battery is obvious to those skilled in the art to which the present disclosure pertains, more detailed description thereof is omitted. Also, the battery pack according to the present disclosure may employ various secondary batteries known at the time of filing of the present disclosure.

The cell assembly <NUM> may include a plurality of secondary batteries. For example, the cell assembly <NUM> may include a plurality of pouch-type secondary batteries. In this case, the pouch-type secondary batteries may be stacked in at least one direction. For example, a pouch-type secondary battery may be configured in a form in which the pouch-type secondary battery stands approximately vertically on the ground such that two wide surfaces thereof are located at left and right sides, a sealing part is located on upper and lower parts, and front and rear pars thereof. Also, the secondary battery standing as above may be arranged as a plurality of secondary batteries such that the plurality of secondary batteries are parallel horizontally in a form in which wide surfaces thereof face each other.

Also, a plurality of cell assemblies <NUM> may be provided to the battery pack. That is, one pack case <NUM> may include the plurality of cell assemblies <NUM> therein, and the plurality of cell assemblies <NUM> may be arranged horizontally and/or vertically. Also, the plurality of cell assemblies <NUM> may be mutually connected in series and/or in parallel through an assembly bus bar, etc..

The cell assembly <NUM> may further include various elements in addition to the secondary battery. For example, the cell assembly <NUM> may include a cartridge. The cartridge includes a polymer material and surrounds a periphery of a pouch-type secondary battery. Also, the cartridges may accommodate a pouch-type secondary battery in an inner space thereof and may be mutually stacked such that the plurality of pouch-type secondary batteries are arranged in parallel. Alternatively, the cell assembly <NUM> may further include a cell cover in addition to the secondary battery. The cell cover may include a metallic material such as aluminum and two cell covers are combinable as one unit and may accommodate one or more pouch-type secondary batteries in an inner space thereof while they are combined.

Also, the cell assembly <NUM> may further include an assembly case in addition to the secondary battery. The assembly case may be provided in a polyhedron shape such as a rectangular parallelepiped to accommodate one or more cell assemblies <NUM> in an inner space thereof. An assembly terminal may be provided to the outside of the assembly case and connected to another cell assembly <NUM>, or electrically connected to an electrode terminal of the pack case <NUM>.

The pack case <NUM> may include a bottom part <NUM> and a side wall part <NUM>.

Here, the bottom part <NUM> may be provided in a plate form and located under the cell assembly <NUM> in parallel to the ground. For example, the bottom part <NUM> may be configured in an approximately quadrangular plate shape. Also, the cell assembly <NUM> may be seated on the bottom part <NUM>.

The side wall part <NUM> may protrude to a preset height in an upward direction from the bottom part <NUM>. Particularly, the side wall part <NUM> may be located along the bottom part <NUM>, particularly, the periphery of the bottom part <NUM> to form one inner space in a horizontal direction. The cell assembly <NUM> may be accommodated in the inner space. For example, in the case where the bottom part <NUM> is provided in a quadrangular plate shape, the side wall part <NUM> may protrude to a preset height along the periphery of the bottom part <NUM> and so an upper surface thereof may have an approximately quadrangular ring shape when viewed in a direction from an upper part to a lower part. One or more cell assemblies <NUM> may be accommodated in a central part of the quadrangular ring.

Since the bottom part <NUM> may be configured in various shapes depending on a structure of an apparatus on which the battery pack is mounted, for example, an automobile, an upper surface of the side wall part <NUM> may also have various shapes depending on the shape of the bottom part <NUM>. Also, the side wall part <NUM> is not necessarily located at the outermost portion of the bottom part <NUM>, and at least a portion of the bottom part <NUM> may protrude outwardly further than the side wall part <NUM> in a horizontal direction.

The side wall part <NUM> may stand approximately vertically with respect to the bottom part <NUM>. Also, the height of the side wall part <NUM> may change variously. For example, the side wall part <NUM> may have a height which is the same as or similar to the height of the cell assembly <NUM>. Therefore, the side wall part <NUM> may cover at least a portion of a lateral surface of the cell assembly <NUM>.

The pack case <NUM> may accommodate the cell assembly <NUM> in the inner space defined by the bottom part <NUM> and the side wall part <NUM>. That is, the bottom part <NUM> may define a lower part of the pack case <NUM>, and the side wall part <NUM> may define a lateral part of the pack case <NUM>. Therefore, the lower surface of the cell assembly <NUM> may be covered by the bottom part <NUM>, and the lateral surface of the cell assembly <NUM> may be covered by the side wall part <NUM>.

Particularly, in the pack case <NUM> of the battery pack according to the present disclosure, the side wall part <NUM> may at least partially include a hollow, which is described more specifically with reference to <FIG>.

<FIG> is a cross-sectional view taken along a line A1-A1' of <FIG>, and <FIG> is a cross-sectional view taken along a line A2-A2' of <FIG>.

Referring to <FIG>, like a part marked by H, an empty space, that is, a hollow may be provided in the inside of the side wall part <NUM> of the pack case <NUM>. Also, the hollow H may be provided long in a direction perpendicular to a thickness direction of the side wall part <NUM>. That is, a flow direction of fluid in the hollow H may be a direction perpendicular to the thickness direction of the side wall part <NUM>. Here, the direction perpendicular to the thickness direction of the side wall part <NUM> may be a direction on a plane perpendicular to the thickness direction of the side wall part <NUM>. For example, in the configuration of <FIG>, in the case where the hollow H is provided to the left side wall part or the right side wall part, the hollow H is not provided such that a flow channel is provided in an x axis direction, which is the thickness direction of the side wall part <NUM>, but is provided such that the flow channel is provided in one of directions on a y-z plane, which is a plane perpendicular to the thickness of the side wall part <NUM>. Alternatively, in the configuration of <FIG>, in the case where the hollow H is provided to the front side wall part or the rear side wall part, the hollow H may be provided such that a flow channel is provided in one of directions on an x-z plane, which is a plane perpendicular to the thickness of the side wall part <NUM>. A part of the hollow H may be also provided in the thickness direction of the side wall part <NUM>.

Also, an inlet and an outlet may be provided in the hollow H. That is, as marked by I and O in <FIG>, the hollow H may be partially open inwardly and outwardly. Also, a hole which opens the hollow H inwardly may be referred to as the inlet, and a hole which opens the hollow H outwardly may be referred to as the outlet.

According to the configuration of the present disclosure, a gas discharge path including the inlet I, the hollow H, and the outlet O may be provided to the side wall part <NUM> of the pack case <NUM>, and when a gas is generated from the inside of the battery pack, the gas may be swiftly discharged to the outside of the pack case <NUM>. Therefore, explosion of the battery pack due to an increase in inner pressure of the pack case <NUM> by generation of the inner gas may be prevented.

Particularly, according to the configuration of the present disclosure, the length of the gas discharge path may be much longer than the thickness of the side wall part <NUM>. That is, in the pack case <NUM> according to the present disclosure, the gas discharge path includes the inlet I, the hollow H, and the outlet O. The hollow H is not provide in the thickness direction of the side wall part <NUM> but may be provided in a lengthwise direction of the side wall part <NUM> like an arrow of <FIG>, that is, a direction perpendicular to the thickness direction of the side wall part <NUM>. Therefore, the length of the gas discharge path may be much longer than the thickness of the side wall part <NUM>.

Therefore, even when fire occurs in the inside of the batter pack, flame may not be directly emitted to the outside of the battery pack. That is, the flame of the inside of the battery pack may be introduced to the hollow H to some extent, but the hollow H of the side wall part <NUM> may have a considerable length, so the flame may not reach to the outlet O of the side wall part <NUM>. Therefore, according to this aspect of the present disclosure, when fire occurs in the inside of the battery pack, secondary fire, etc. due to outflow of flame to the outside may be effectively prevented.

Also, high temperature gas may be generated when fire occurs. According to the configuration of the present disclosure, leakage of the high temperature gas may be reduced. That is, temperature of the high temperature gas generated from the inside of the battery pack may be reduced while flowing through the hollow H of the side wall part <NUM>, so leakage of the very high temperature gas to the outside may be minimized.

Furthermore, according to the configuration of the present disclosure, even when an impact is applied from the outside of the battery pack, the side wall part <NUM> may relieve the impact. That is, since the side wall part <NUM> includes the hollow H, when the impact is applied from the outside of the battery pack, the impact may be considerably absorbed by the hollow H of the side wall part <NUM>. Therefore, destruction of elements inside the battery pack, for example, a secondary battery or various electric parts may be prevented by reducing transfer of the impact from the outside to the inside of the battery pack.

Preferably, the hollow H may be provided in the peripheral direction of the bottom part <NUM>. Here, the peripheral direction of the bottom part <NUM> may be a horizontal direction among directions perpendicular to the thickness of the side wall part <NUM>, that is, a direction parallel to the surface of the bottom part <NUM>. For example, in the case of the left side wall part and the right side wall part in the configuration of <FIG>, the peripheral direction may mean a y axis direction. Also, in the case of the front side wall part and the rear side wall part in the configuration of <FIG>, the peripheral direction may mean an x axis direction.

Meanwhile, the configurations of the side wall parts <NUM> illustrated in <FIG> are mere examples, and the present disclosure is not limited thereto and the side wall part <NUM> may be configured in various forms.

<FIG> is a perspective view schematically illustrating a configuration of the side wall part <NUM> of the pack case <NUM> according to another embodiment of the present disclosure, and <FIG> is a cross-sectional view taken along a line A4-A4' of <FIG>. For convenience of description, <FIG> illustrates the inner surface and the upper surface of the side wall part <NUM> are cut. Here, the side wall part <NUM> illustrated in <FIG> may configure a partial side wall part, for example, all or a portion of the right side wall part in the pack case <NUM> of <FIG>.

Referring to <FIG> and <FIG>, the pack case <NUM> may include two or more hollows H. That is, the side wall part <NUM> of the pack case <NUM> includes an empty space therein, and the inner space may be divided into two or more compartments by a partition wall. Also, each compartment may configure a separate hollow H. For example, the side wall part <NUM> of the pack case <NUM> may include two hollows as marked by H1 and H2 in <FIG>. According to the configuration of the present disclosure, a discharge path of gas, flame, etc. may be provided in various numbers or various forms.

Particularly, in the pack case <NUM>, two or more hollows may be vertically arranged. For example, as illustrated in <FIG> and <FIG>, the side wall part <NUM> may include two hollows, and the two hollows may be vertically arranged. That is, the inner space of the side wall part <NUM> may include an upper hollow H1 and a lower hollow H2.

Here, a vertical through part may be provided between the two or more vertically arranged hollows. For example, in the configuration illustrated in <FIG> and <FIG>, the upper hollow H1 may be separated from the lower hollow H2 by a central partition wall, and a vertical opening, that is, a through part may be provided to at least a part of the partition wall as marked by P. Also, the inner space of the upper hollow H1 may be connected to the inner space of the lower hollow H2 via the through part P.

In the above configuration, the inlet I and the outlet O may be provided in different hollows, respectively. For example, in the configuration of <FIG> and <FIG>, the inlet I provided to the inside of the battery pack may be provided in the upper hollow H1, and the outlet O provided to the outside of the battery pack may be provided in the lower hollow H2.

According to this configuration of the present disclosure, the length of the gas discharge path from the inlet I to the outlet O may increase remarkably. For example, referring to the configuration of <FIG> and <FIG>, the length of the hollow from the inlet I to the outlet O may be approximately sum of a length of the lower hollow H2 from the inlet I to the through part P and a length of the upper hollow H1 from the through part P to the outlet O. Therefore, the length of the hollow from the inlet I to the outlet O may be much longer than the length of the side wall part <NUM>. Therefore, in this case, even when flame of the inside of the battery pack is introduced through the inlet I, it is very difficult for the flame to reach the outlet O by way of the hollow, so direct leakage of the flame to the outside of the battery pack may be prevented more surely. Also, in this case, temperature of gas discharged through the outlet O may be lowered while the gas passes through the hollow.

More preferably, in the pack case <NUM>, the inlet I and the outlet O may be provided at an end part of one side of two or more hollows, and the through part P may be provided at an end part of an opposite side of the two or more hollows, that is, the end part of the another side. For example, in the configuration of <FIG>, the inlet I and the outlet O may be provided at the left end part of the side wall part <NUM>, and the through part P may be provided at the right end part of the side wall part <NUM>.

According to this configuration of the present disclosure, the length of the gas discharge path from the inlet I to the outlet O may be maximized. For example, in the configuration of <FIG>, a gas introduced through the inlet I of the lower hollow H2 flows in a right direction through the lower hollow H2, and then may be introduced to the upper hollow H1 through the through part P at the right end part of the side wall part <NUM>. Then, the gas flows in a left direction through the upper hollow H1, and then may be discharged to the outside of the pack case <NUM> through the outlet O at the left end part of the side wall part <NUM>. In this case, the length of the gas discharge path from the inlet I to the outlet O may be a length corresponding to approximately twice a horizontal length of the side wall part <NUM>. Therefore, possibility of exposure of flame of the battery pack to the outside is reduced maximally, and temperature of the discharged gas is also lowered maximally.

<FIG> is a perspective view schematically illustrating a configuration of the side wall part <NUM> of the pack case <NUM> according to still another embodiment of the present disclosure, and <FIG> is a cross-sectional view taken along a line A5-A5' of <FIG>. For convenience of description, <FIG> illustrates the inner surface and the upper surface of the side wall part <NUM> are cut. Meanwhile, the side wall part <NUM> illustrated in <FIG> may configure a partial side wall part, for example, all or a portion of the right side wall part in the pack case <NUM> of <FIG>. In the configurations of <FIG> and <FIG>, for parts to which descriptions of the above embodiments are equally or similarly applicable, descriptions thereof are omitted, and different parts are mainly described.

Referring to <FIG> and <FIG>, the pack case <NUM> may include three hollows vertically as marked by H1, H2, and H3. Also, the three hollows, that is, the upper hollow H1, an intermediate hollow H2, and the lower hollow H3 may be provided such that a flow direction of fluid in the inside is configured in a horizontal direction perpendicular to the thickness direction of the side wall part.

Also, a through part P may be provided between the three hollows. For example, the through part P may be provided between the upper hollow H1 and the intermediate hollow H3, and between the intermediate hollow H3 and the lower hollow H2. In this case, the through part P between the lower hollow H2 and the intermediate hollow H3 may be provided at a right end part of the side wall part <NUM>, and the through part P between the intermediate hollow H3 and the upper hollow H1 may be provided at a left end part of the side wall part <NUM>. Also, the inlet I may be provided at a left end part of the lower hollow H2, and the outlet O may be provided at a right end part of the upper hollow H1.

According to the embodiment, a discharge path of gas or flame may be lengthened even more than the embodiment of <FIG> and <FIG>. That is, in the embodiment of <FIG> and <FIG>, a gas introduced through the inlet I may flow in a right direction along the lower hollow H2 and then be introduced to the intermediate hollow H3 through the through part P and flow in a left direction. Then, the gas which reaches a left end part of the intermediate hollow H3 may be introduced to the upper hollow H1 through the through part P and may flow in the right direction and be discharged through the outlet O at a right end part of the upper hollow H1. Therefore, in this case, the discharge path of the gas may have a length approximately three times the horizontal length of the side wall part <NUM>.

<FIG> is a perspective view schematically illustrating a configuration of the side wall part <NUM> of the pack case <NUM> according to still another embodiment of the present disclosure. For convenience of description, <FIG> illustrates the inner surface and the upper surface of the side wall part <NUM> are cut. The side wall part <NUM> illustrated in <FIG> may configure, for example, all or a portion of the right side wall part in the pack case <NUM> of <FIG>. In the embodiment, parts which are different from the above embodiments are mainly described.

Referring to <FIG>, the pack case <NUM> may include a plurality of inlets I and a plurality of outlets O. That is, in the configuration of <FIG>, two hollows classified as an upper hollow H1 and a lower hollow H2 are provided to the side wall part <NUM>. Three inlets I are provided in the lower hollow H2, and three outlets O are provided in the upper hollow H1. In this case, a gas introduced through the three inlets I may flow horizontally through the lower hollow H2, reach a through part P, and move to the upper hollow H1. The gas introduced to the upper hollow H1 may flow through the upper hollow H1 horizontally and then be discharged to the outside through the plurality of outlets O.

Also, the pack case <NUM> may include a plurality of through parts P. That is, in the configuration of <FIG>, two through parts P are provided between the upper hollow H1 and the lower hollow H2.

According to the configuration of the present disclosure, a gas discharge may be performed more swiftly. That is, in the case where a large amount of gas are generated from the inside of the battery pack or a gas is generated from a specific part, the relevant gas may be introduced to the hollow in various directions through the plurality of inlets I, and swiftly discharged to the outside through the plurality of through parts P and the plurality of outlets O.

Particularly, in this case, the through parts P may not be provided, horizontally, at locations same as or similar to those of the inlets I and/or the outlets O, but may be provided at different locations. For example, as illustrated in <FIG>, the through hole P may be located between the inlet I and the outlet O. According to this configuration, even when the plurality of inlets I, outlets O, and/or through parts P are provided, the length of the gas discharge path may be lengthened maximally.

<FIG> is a perspective view illustrating a part separated from a pack case <NUM> of the battery pack of <FIG>.

Referring to <FIG>, the pack case <NUM> includes the bottom part <NUM> and the side wall part <NUM>. The side wall part <NUM> may include a first side wall <NUM> and a second side wall <NUM>. Here, like the side wall parts <NUM> illustrated in <FIG>, the first side wall <NUM> may be a side wall including a hollow therein. Also, the second side wall <NUM> may be a side wall not including a hollow. Also, the various embodiments of the side wall part <NUM> illustrated in <FIG> are applicable to the first side wall <NUM> in the configuration of <FIG>.

According to the configuration of the present disclosure, the pack case <NUM> may be more easily manufactured. Manufacturing the side wall part <NUM> at a time such that a hollow is provided to a preset part and a hollow is not provided to the other part may be difficult. However, since the present embodiment may manufacture the first side wall <NUM> including a hollow and the second side wall <NUM> not including a hollow separately, the side wall part <NUM> including a hollow at only a preset part may be easily manufactured. Particularly, the side wall part <NUM> may be configured such that the first side wall <NUM> includes the hollow therein in the form of an extruded frame, and then opposite ends of the first side wall <NUM> are covered. The first side wall <NUM> may include an inlet I and an outlet O. Also, in the case where the side wall part <NUM> includes a plurality of hollows and so one or more through parts P are provided, the through part P may be formed by boring a hole in an outer surface of the first side wall <NUM>, for example, an upper surface or a lower surface of the first side wall <NUM> in order to form the through part P, inserting a drill through the hole, and boring a hole in a partition wall between the hollows.

In this configuration, the first side wall <NUM> may be arranged in the peripheral direction of the bottom part <NUM> with respect to the second side wall <NUM>. That is, in the pack case <NUM> of <FIG>, the whole of a front side wall part, a rear side wall part, and a left side wall part, and a portion of a right side wall part may configure the second side wall <NUM>. Also, most of the right side wall part of the pack case <NUM> may configure the first side wall <NUM>. Therefore, the first side wall <NUM> and the second side wall <NUM> may be coupled to provide an upper surface in a ring shape.

In this case, opposite ends of the first side wall <NUM> may be coupled to the second side wall <NUM>. That is, the opposite ends of the first side wall <NUM> marked by B1 in <FIG> contact opposite ends of the second side wall <NUM> to define an inner space, and the contact parts may be coupled and fixed. In this case, a coupling and fixing method of the first side wall <NUM> and the second side wall <NUM> may be various. Welding may be used as a representative method. That is, the opposite ends of the first side wall <NUM> may be coupled and fixed to the second side wall <NUM> by using welding.

Meanwhile, though the embodiments mainly illustrate the hollow is provided in a horizontal direction among directions perpendicular to the thickness of the side wall part <NUM>, the present disclosure is not limited thereto and the hollow may be provided in various forms.

<FIG> is a perspective view schematically illustrating a configuration of the side wall part <NUM> of the battery pack according to another embodiment of the present disclosure, and <FIG> is a cross-sectional view taken along a line A6-A6' of <FIG>. In the embodiment of <FIG> and <FIG>, parts which are different from the above embodiments are mainly described.

Referring to <FIG> and <FIG>, the side wall part <NUM> of the pack case <NUM> may include a plurality of hollows, and each hollow may be provided in a vertical direction among directions perpendicular to the thickness direction of the side wall part <NUM>. In this case, in the case where an inlet I is provided to a part marked by B2 in <FIG>, fluid, for example, gas introduced through the inlet I may flow in an upward direction through a right hollow and be introduced to a central hollow through a through part P, and then flow in a downward direction. Then, the gas may be introduced to a left hollow through a through part P located in a lower portion of the central hollow and then flow in the upward direction and be discharged to the outside of the pack case <NUM>.

According to the configuration of the present disclosure, like the previous embodiments in which the hollow is provided horizontally, the length of the gas discharge path may be advantageously lengthened. Particularly, as illustrated in <FIG>, the pack case <NUM> of the battery pack may be provided vertically long, and in this case, a plurality of hollows may be easily provided by providing vertical hollows.

Furthermore, the side wall part <NUM> having a configuration in which a horizontal hollow and a vertical hollow are mixed may be possible. In this case, since the pack case <NUM> of the battery pack may be configured in various forms and the inlet I and the outlet O may be also arranged at various locations, the present disclosure is efficiently adaptable to various battery pack configurations or mounting locations through an appropriate arrangement of the horizontal hollow and the vertical hollow.

Preferably, the pack case <NUM> may at least partially include a metallic material. For example, the pack case <NUM> may include an aluminum material on the whole. A metallic material such as aluminum has excellent mechanical rigidity and so may effectively protect the cell assembly <NUM>, etc. against an external impact, etc. Particularly, since the metallic material is not easily molten compared with a plastic material when fire occurs in the inside of the battery pack, flame may not easily leak to the outside of the battery pack. Furthermore, the battery pack according to the present disclosure may effectively prevent leakage of flame through a configuration of the hollow of the side wall part <NUM>.

Meanwhile, though not shown in the drawings, the pack case <NUM> of the battery pack according to the present disclosure may further include a cover part.

The cover part may be mounted on an upper end of the side wall part <NUM> to seal an inner space of the pack case <NUM>. Therefore, the cover part may cover an upper side of the cell assembly <NUM>. For example, similarly with the bottom part <NUM>, the cover part may be configured in a plate form and mounted on the upper end of the side wall part <NUM>. Also, the cover part may be fixed to the side wall part <NUM> by using a fastening member such as a bolt or welding, etc..

The battery pack is applicable to an automobile such as an electric automobile or a hybrid automobile. That is, an automobile according to the present disclosure may include the battery pack according to the present disclosure. Particularly, in the case of an automobile, since a passenger may be nearby and the automobile may be adjacent to a fuel tank of another automobile, when fire occurs in the inside of the battery pack, flame thereof should not be easily exposed to the outside. Since the battery pack according to the present disclosure has an excellent flame exposure prevention effect, the safety of an automobile may be improved.

Meanwhile, although terms representing directions such as up, down, left, right, front, and rear are used in the present specification, it is obvious to those skilled in the art that these terms are used for convenience of description only, and the terms may change depending on a location of an object considered as a subject or a location of an observer, etc..

Claim 1:
A battery pack comprising:
a cell assembly (<NUM>) comprising a plurality of secondary batteries; and
a pack case (<NUM>) comprising a bottom part (<NUM>) having a plate shape and located under the cell assembly (<NUM>), and a side wall part (<NUM>) protruding from the bottom part (<NUM>) to a preset height, the pack case (<NUM>) accommodating the cell assembly (<NUM>) in an inner space defined by the bottom part (<NUM>) and the side wall part (<NUM>),
wherein the side wall part (<NUM>) of the pack case (<NUM>) comprises a hollow (H) in a direction at least partially perpendicular to a thickness direction of the side wall part (<NUM>), wherein the hollow is provided in the inside of the side wall part and the hollow (H) comprises an inwardly open inlet (I) and an outwardly open outlet (O),
characterized in that
the hollow (H) is provided long in a peripheral direction of the bottom part (<NUM>),
the hollow (H) is provided as two or more hollows (H1, H2) in the side wall part (<NUM>), and the two or more hollows (H1, H2) are vertically arranged in the side wall part (<NUM>), a vertical through part (P) is provided between the two or more hollows (H1, H2), and the inlet (I) and the outlet (O) are provided in different hollows (H1, H2), respectively, and wherein the side wall part (<NUM>) comprises a first side wall (<NUM>) comprising the hollow (H) and a second side wall (<NUM>) not comprising the hollow (H), and the inlet (I) and the outlet (O) are provided at an end part of one side of two or more hollows (H1, H2) and the through part (P) is provided at an end part of an opposite side of the two or more hollows.