Patent Description:
Secondary batteries are attracting the attention as a new eco-friendly and energy efficient source of energy for their advantages such as remarkably reducing the use of fossil fuels and not generating by-products from the use of energy.

Accordingly, secondary batteries are increasingly used in a wide range of device applications. For example, secondary batteries are widely used as not only an energy source of multifunctional small products such as wireless mobile device or wearable device, but also an energy source of electric vehicles and hybrid electric vehicles suggested as an alternative to gasoline vehicles and diesel vehicles or energy storage systems (ESSs).

Lithium secondary batteries widely used in recent years have the operating voltage of about <NUM>. 5V to <NUM>. 5V for an individual lithium secondary battery. Accordingly, electric vehicles or energy storage systems requiring high capacity and high output use battery packs as their energy source, and a battery pack includes battery modules connected in series and/or in parallel, each battery module including lithium secondary batteries connected in series and/or in parallel.

Depending on the output or capacity of the battery packs required for electric vehicles, the number of lithium secondary batteries in a battery module may increase or the number of battery modules in a battery pack may increase.

However, as the battery pack includes a larger number of lithium secondary batteries, more serious damage occurs in the event of fires and explosion.

For example, when an event occurs in any battery module such as a short between lithium secondary batteries or an abnormal temperature rise, a large amount of venting gas may occur in the lithium secondary batteries, and when degradation is aggravated, in addition to the venting gas, high temperature spark including electrode active materials and aluminum particles may flare up. In this instance, the venting gas and the high temperature spark causes thermal damage to the adjacent battery module, and there is a very high risk that an additional event may occur to the other battery modules.

Accordingly, there is a need for the development of a gas venting path for allowing venting gas to flow out of the battery pack quickly and safely while minimizing the influence on other battery modules in the event of venting gas and high temperature spark in any battery module.

Further prior art is described in <CIT>, <CIT>, <CIT>, <CIT>, and <CIT>.

The present disclosure is designed to solve the above-described problem, and therefore the present disclosure is directed to providing a battery pack with a gas venting path for minimizing the influence on other battery modules in the event of venting gas or spark in any battery module.

According to the present disclosure, there is provided a battery pack including a plurality of battery modules, each including battery cells, a module housing accommodating the battery cells and a gas venting channel in communication with an inside of the module housing; and a pack case accommodating the plurality of battery modules, the pack case including a top plate to cover upper parts of the plurality of battery modules, the top plate having a venting port, wherein the gas venting channel of each battery module is in communication with the venting port, wherein the gas venting channel is disposed on the module housing, and includes a duct of a hollow structure; a gas inlet provided on one surface of the duct; and a gas outlet provided on the other surface of the duct at a predetermined distance from the gas inlet in an extension direction of the duct, wherein the gas inlet matches an opening of the module housing and the gas outlet matches the venting port of the top plate, and the venting port includes a rupturable membrane which ruptures under a predetermined pressure or above.

The top plate may include a plurality of the venting ports, and each venting port may be vertically connected to the gas outlet of each battery module.

The top plate may be formed in a hollow structure and may include a lower plate facing an upper surface of the gas venting channel; and an upper plate opposite to the lower plate with an empty space therebetween, and the venting port may include a first venting port in the lower plate, the first venting port vertically connected to the gas outlet; and a second venting port in the upper plate at a predetermined distance apart from the first venting port in a horizontal direction.

The rupturable membrane may be in any one of the first venting port and the second venting port, and a mesh may be in the other venting port.

The battery pack may further include an outer cover plate configured to surround an upper area of the top plate.

The duct may include a plurality of partitions to partition an internal space.

The duct may include a plurality of narrow passages extended in a lengthwise direction between the plurality of partitions.

The battery cells may include first group battery cells and second group battery cells that are disposed to face each other with a firewall interposed therebetween configured to partition an internal space of the module housing.

The opening may include a first opening on a left top side of the module housing and a second opening on a right top side of the module housing with respect to the firewall, and the gas inlet may include a first gas inlet which matches the first opening and a second gas inlet which matches the second opening.

The gas outlet may include a first gas outlet in a left edge area of the duct and a second gas outlet in a right edge area of the duct.

The opening may be closed with a cap made of a hot melt material.

The module housing and the gas venting channel may be integrally formed.

According to an aspect of the present disclosure, it is possible to provide a battery pack having a gas venting path for allowing venting gas to flow out of the pack case quickly and safely without affecting other battery modules when venting gas or spark is generated from any battery module.

The effect of the present disclosure is not limited to the above-described effects, and these and other effects will be clearly understood by those skilled in the art from the present disclosure and the accompanying drawings.

Hereinafter, the exemplary embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. Therefore, the embodiments described herein and the illustrations shown in the drawings are just an exemplary embodiment of the present disclosure, but not intended to fully describe the technical aspects of the present disclosure.

The terms top plate and base plate are used herein to define the main parts of a pack case, but when the battery pack is for example flipped upside down, it is obvious that the top plate corresponds to the bottom of the battery pack and the base plate corresponds to the top of the battery pack. That is, it should be noted that the top plate and the base plate may be interpreted differently from the dictionary meaning depending on the placement of the battery pack or the position of an observer.

<FIG> is a schematic perspective view of a battery pack according to an embodiment of the present disclosure, <FIG> is a partial exploded perspective view of the battery pack of <FIG>, and <FIG> is a conceptual diagram of a gas venting path of the battery pack of <FIG>.

As shown in <FIG> and <FIG>, the battery pack <NUM> according to an embodiment of the present disclosure includes a plurality of battery modules <NUM>, and a pack case <NUM> accommodating the plurality of battery modules <NUM>, wherein a gas venting channel <NUM> of each battery module <NUM> is connected to a venting port <NUM> of a top plate <NUM> of the pack case <NUM> for gas venting when gas is generated from each battery module <NUM>.

As described below in detail, when gas is generated from each battery module <NUM>, the battery pack <NUM> of the present disclosure may allow venting gas to move to the edge of the battery module <NUM> and exit the pack case <NUM> through the venting port <NUM> of the pack case <NUM> on each battery module <NUM> as shown in <FIG>. The venting port <NUM> includes a rupturable membrane <NUM> that may rupture under a predetermined pressure or above, and the rupturable membrane <NUM> may be closed in normal condition, and when venting gas occurs, may be torn open by the pressure.

When gas is generated from any battery module <NUM>, the battery pack <NUM> according to the present disclosure may allow venting gas to exit the pack case <NUM> directly from the corresponding battery module <NUM>, thereby preventing the spread of heat or high temperature spark to the other battery module <NUM> in the pack case <NUM>. Accordingly, the battery pack <NUM> of the present disclosure may prevent thermal runaway propagation to the other battery modules <NUM> in the event of high temperature venting gas in any battery module <NUM>.

Hereinafter, the battery module <NUM> and the pack case <NUM> according to an embodiment of the present disclosure for achieving the above-described effect will be described in detail.

<FIG> is a perspective view of the battery module <NUM> according to an embodiment of the present disclosure, <FIG> is an exploded perspective view of the main parts of the battery module <NUM> of <FIG>, <FIG> is a diagram showing the bottom of the battery module <NUM> of <FIG>, and <FIG> is an enlarged diagram of section A in <FIG>.

To begin with, the battery module <NUM> according to an embodiment of the present disclosure will be described with reference to <FIG>. The battery module <NUM> includes a plurality of battery cells <NUM>, a module housing <NUM>, a firewall <NUM>, a heat sink <NUM> and the gas venting channel <NUM>.

The battery cell <NUM> may include a pouch-type battery cell <NUM> that has high energy density and is easy to stack. As shown in <FIG>, the pouch-type battery cells <NUM> may be stacked in the horizontal direction (Y axis direction) upright in the vertical direction (Z axis direction) to form a cell stack. As opposed to this embodiment, the battery module <NUM> may include prismatic battery cells <NUM> of a rectangular prism shape or cylindrical battery cells <NUM>.

The module housing <NUM> is a component used to receive the plurality of battery cells <NUM>, and may be formed with a hermetic structure using a material having high mechanical strength to protect the plurality of battery cells <NUM> from external physical and chemical factors. The module housing <NUM> may include a lower housing <NUM> to cover the lower parts of the battery cells <NUM> and an upper housing <NUM> to cover the upper parts of the battery cells <NUM>. The upper housing <NUM> and the lower housing <NUM> may be in the shape of an approximately U-shaped plate, and they may be coupled to each other by bolting and/or welding.

In general, the conventional battery module <NUM> includes one cell stack received in one module housing <NUM>. However, the battery module <NUM> of this embodiment includes a plurality of cell stacks received in one module housing <NUM>.

For example, as shown in <FIG>, the battery module <NUM> of this embodiment includes first group battery cells G1 that form a cell stack and second group battery cells G2 that form another cell stack, and the first group battery cells G1 and the second group battery cells G2 may be received in the module housing <NUM> such that they are disposed face each other with the firewall <NUM> interposed therebetween, wherein the firewall <NUM> divides the internal space of the module housing <NUM> into two.

That is, the first group battery cells G1 are positioned in one space of the lower housing <NUM> partitioned by the firewall <NUM> and the second group battery cells G2 are positioned in the other space of the lower housing <NUM>. Each of the upper parts of the first group battery cells G1 and the second group battery cells G2 positioned as described above may be received in each of the two hermetic spaces surrounded by the upper housing <NUM>, the lower housing <NUM> and the firewall <NUM>, with the upper parts covered with the upper housing <NUM>.

Here, the firewall <NUM> refers to a plate-shaped structure that partitions the internal space of the module housing <NUM> into two physically separated spaces. The firewall <NUM> may be made of, for example, a fire-resistant material or a stiff material, and may have a sheet of fire-resistant material (for example, mica) attached to two surfaces. The firewall <NUM> may block heat transfer between the first group battery cells G1 and the second group battery cells G2, and prevent the module housing <NUM> from sagging in the middle due to the top and bottom connected to the center of the upper housing <NUM> and the lower housing <NUM>, respectively.

Although not shown, for example, the upper housing <NUM> may have an opening that is open at a part of the central side area. The opening may be used to install a connection means for electrically connecting the first group battery cells G1 to the second group battery cells G2. The connection means may include a metal rod-shaped busbar, and after the connection means is installed, the opening may be sealed up.

One battery module <NUM> according to this embodiment may have, for example, the capacity equivalent to two battery modules <NUM>, each including one cell stack received in one module housing <NUM>, but may reduce the volume. Accordingly, the battery modules <NUM> may be advantageous in reducing the left-right width (X axis direction) of the pack case <NUM> when fabricating the battery pack <NUM>.

The heat sink <NUM> may be provided at the bottom of the module housing <NUM>, in other words, on the lower surface of the lower housing <NUM> as shown in <FIG>. Here, the heat sink <NUM> refers to a cooling component that absorbs heat by indirect contact with the battery cells <NUM>. The heat sink <NUM> may have an aluminum plate shape with an internal flow channel, and as shown in this embodiment, may be incorporated into the lower housing <NUM> or may be detachably attached to the surface of the lower housing <NUM>.

The gas venting channel <NUM> is used to allow venting gas inside the battery module <NUM> out, and one side of the gas venting channel <NUM> may be in communication with the inside of the module housing <NUM> and the other side thereof may be in communication with the outdoor environment. The gas venting channel <NUM> may be attached to the outer side of the module housing <NUM> or may be integrally formed with the module housing <NUM>.

The gas venting channel <NUM> of this embodiment may have a hollow flat rectangular box shape with a size approximately corresponding to the upper surface of the upper housing <NUM>, and may be attached onto the module housing <NUM>. Additionally, the gas venting channel <NUM> may be made of a fire-resistant material to prevent deformation caused by high temperature gas or high temperature spark.

Specifically, referring to <FIG> and <FIG>, the gas venting channel <NUM> includes a duct <NUM> of a hollow structure, a gas inlet <NUM> that corresponds to a hole through which gas enters the duct <NUM>, and a gas outlet <NUM> that corresponds to a hole through which gas exits the duct <NUM>.

The duct <NUM> has an area corresponding to the upper surface of the module housing <NUM> and is hollow to allow gas to flow inside. Additionally, the duct <NUM> may include a plurality of partitions <NUM> to partition the internal space, and the partitions <NUM> may be spaced apart from each other in the widthwise direction and extended in the lengthwise direction.

For example, as shown in <FIG>, the duct <NUM> is partitioned by the partitions <NUM> to form narrow passages <NUM> between the partitions <NUM>. The high temperature spark or flame moving together with the venting gas may be restrained from moving or extinguished due to bottlenecking or trapping while moving in the narrow passages. As an additional solution to suppress the movement of the high temperature spark or flame, a metal mesh (not shown) may be additionally applied to the narrow passages or the gas inlet <NUM>.

The gas inlet <NUM> may be provided on the lower surface of the duct <NUM> and match an opening <NUM> on top of the module housing <NUM>.

More specifically, as shown in <FIG>, the gas inlet <NUM> may have a long hole shape that is as large as the width of the module housing <NUM> in the central area of the lower surface of the duct <NUM>. The gas inlet <NUM> may include a first gas inlet 152a and a second gas inlet 152b, and the first gas inlet 152a and the second gas inlet 152b may be symmetric with respect to the center of the module housing <NUM>.

Additionally, as shown in <FIG> and <FIG>, the opening <NUM> of the module housing <NUM> includes a first opening 123a on the left top side of the module housing <NUM> and a second opening 123b on the right top side of the module housing <NUM> with respect to the firewall <NUM>. When the gas venting channel <NUM> is attached to the upper surface of the module housing <NUM>, the first opening may vertically match the first gas inlet 152a and the second opening may vertically match the second gas inlet 152b.

Accordingly, gas and high temperature spark generated from the first group battery cells G1 may enter the duct <NUM> through the first opening 123a and the first gas inlet 152a, and gas and high temperature spark generated from the second group battery cells G2 may enter the duct <NUM> through the second opening 123b and the second gas inlet 152b.

Additionally, as shown in <FIG>, a barrier 151a in the internal space of the duct <NUM> between the first gas inlet 152a and the second gas inlet 152b may prevent gas generated from the first group battery cells G1 from moving to the second group battery cells G2.

Although not shown, the opening <NUM> may be closed with a cap (not shown) made of a hot melt material (for example, rubber or plastic). The cap may prevent impurities from entering the module housing <NUM> through the opening <NUM> in normal condition. When venting gas or high temperature spark occurs, the cap is melted down by heat and pressure to open the opening <NUM>. The cap may be replaced with a mesh.

The gas outlet <NUM> may be provided on the upper surface of the duct <NUM>. The gas outlet <NUM> may include a first gas outlet 153a and a second gas outlet 153b. The gas outlet <NUM> may vertically match the venting port <NUM> of the top plate <NUM>.

The first gas outlet 153a may be provided at a predetermined distance from the first gas inlet 152a in the left extension direction (-X axis direction) of the duct <NUM>, and the second gas outlet 153b may be provided at a predetermined distance from the second gas inlet 152b in the right extension direction (+X axis direction) of the duct <NUM>.

That is, referring to <FIG> and <FIG>, the first gas outlet 153a acts as an exit of venting gas entering the duct <NUM> through the first gas inlet 152a, and the second gas outlet 153b acts as an exit of venting gas entering the duct <NUM> through the second gas inlet 152b.

The first gas outlet 153a and the second gas outlet 153b may be each formed in a hole shape of sufficient size to vertically match the venting port <NUM>, and may be provided at the left edge area and the right edge area of the upper surface of the duct <NUM>, respectively.

The pack case <NUM> is a component used to receive the battery modules <NUM>, and as shown in <FIG>, may include a base plate <NUM>, the top plate <NUM>, a left side frame <NUM>, a right side frame <NUM>, a front cover <NUM> and a rear cover <NUM>.

In particular, the top plate <NUM> is configured to cover the upper parts of the battery modules <NUM>, and includes a plurality of venting ports <NUM> through which venting gas exits.

As shown in <FIG> and <FIG>, the venting port <NUM> may be at a location vertically corresponding to the first gas outlet 153a or the second gas outlet 153b of each battery module <NUM> when the battery modules <NUM> are covered with the top plate <NUM>. For example, in this embodiment, the battery modules <NUM> are arranged along the lengthwise direction (Y axis direction) of the pack case <NUM> with the first gas outlet 153a and the second gas outlet 153b of each battery module <NUM> at the two edges in the widthwise direction of the pack case <NUM>. Half of the venting ports <NUM> is provided at the left edge area of the top plate <NUM> and the remaining half is provided at the right edge area of the top plate <NUM>, so the gas outlets <NUM> of all the battery modules <NUM> and the venting ports <NUM> vertically match and are connected in a one-to-one relationship.

The arrangement structure of the battery modules <NUM> received in the pack case <NUM> or the positions of the first gas outlet 153a and the second gas outlet 153b of the battery module <NUM> may be properly changed as necessary differently from this embodiment. In this case, the venting ports <NUM> may be positioned in the top plate <NUM> to match the changed positions of the first gas outlet 153a and the second gas outlet 153b.

The venting port <NUM> of this embodiment includes a through-hole <NUM> and the rupturable membrane <NUM>.

The through-hole <NUM> may have a size that is equal to or larger than the gas outlet <NUM> to prevent the leakage of venting gas, and a sealing member (not shown) such as an O-ring) may be applied around the through-hole <NUM>.

The rupturable membrane <NUM> may be configured to cover the through-hole <NUM> and rupture when the internal pressure of the pack case <NUM> exceeds the predetermined pressure. According to this configuration, it is possible to prevent the infiltration of moisture or impurities into the pack case <NUM> in normal condition, and when venting gas occurs, the rupturable membrane <NUM> ruptures by the heat and pressure of the venting gas to open the through-hole <NUM> to allow the venting gas to flow out of the pack case <NUM>. In this instance, it is possible to allow the venting gas out through the through-hole quickly without leakage due to a large pressure difference between the inside and outside of the pack case <NUM>.

The rupturable membrane <NUM> may be in the form of an aluminum or plastic thin film, but is not limited thereto, and may be made of any material that can rupture by the predetermined pressure. Additionally, the rupturable membrane <NUM> may include at least one notch (not shown) that is partially cut in the thicknesswise direction from the surface. The notch may help the rupturable membrane <NUM> to easily rupture when the predetermined pressure is applied.

In this embodiment, a support frame <NUM> of a frame shape may be used to easily mount the rupturable membrane <NUM> in the through-hole <NUM>.

The support frame <NUM> may support the periphery of the rupturable membrane <NUM>, and the through-hole <NUM> may be covered with the rupturable membrane <NUM> by mounting the support frame <NUM> in the top plate <NUM> by bolting or riveting. In this case, compared to when the rupturable membrane <NUM> is directly mounted in the top plate <NUM>, it is easier to assemble and sealability may be improved.

Additionally, the top plate <NUM> according to this embodiment may further include a partition extended across the top plate <NUM> in the widthwise direction and running down from the surface to form a wall. The top plate <NUM> may include a plurality of partitions arranged at a predetermined interval along the lengthwise direction (Y axis direction) of the top plate <NUM>. The partitions may prevent the deformation of the top plate <NUM>, and block the heat transfer between the adjacent battery modules <NUM> when a fire occurs as they are disposed in a space between the battery modules <NUM> when the battery modules <NUM> are covered with the top plate <NUM>.

By the configuration of the battery pack <NUM> according to an embodiment of the present disclosure, when venting gas occurs in the battery module <NUM>, the venting gas may exit in the following flow.

Venting gas occurs in each battery module <NUM> -> the gas exits the module housing <NUM> through the first opening 123a or the second opening 123b on top of the module housing <NUM> -> the gas enters the gas venting channel <NUM> through the first gas inlet 152a or the second gas inlet 152b of the venting gas channel -> the venting gas moves to the first gas outlet 153a or the second gas outlet 153b at the two edges of the battery module <NUM> along the duct <NUM> -> the rupturable membrane <NUM> of the venting port <NUM> ruptures to open the venting port <NUM> -> the venting gas exits the pack case <NUM> through the open venting port <NUM>.

Accordingly, as described above, since the battery pack <NUM> according to an embodiment of the present disclosure is configured to allow venting gas to exit the pack case <NUM> directly from each battery module <NUM> without moving in the pack case <NUM>, when venting gas occurs due to a failure in any battery module <NUM>, the venting gas does not cause thermal damage to the other battery modules <NUM>. Accordingly, when a fire occurs in one battery module <NUM>, the present disclosure may prevent thermal runaway that causes the fire to spread due to the transfer of venting gas or high temperature spark to the other battery module <NUM>. Additionally, the battery pack <NUM> of the present disclosure may intuitively detect the battery module <NUM> at which the fire occurred from the location at which venting gas comes out, which makes it possible to accurately and effectively take an action, for example, concentratively supplying fire-fighting water to the corresponding battery module <NUM>.

Subsequently, a variation of the top plate <NUM> and another embodiment of the present disclosure will be described with reference to <FIG> and <FIG>.

To begin with, referring to <FIG>, the top plate 220A according to the variation has a hollow structure, and includes a lower plate <NUM> facing the upper surface of the gas venting channel <NUM>, and an upper plate <NUM> opposite to the lower plate with an empty space O therebetween.

Additionally, the venting port includes a first venting port 221A in the lower plate <NUM>, and a second venting port 221B in the upper plate <NUM> at a predetermined distance apart from the first venting port 221A in the horizontal direction, wherein the first venting port 221A matches and is vertically connected to the gas outlet <NUM> of the gas venting channel <NUM>. The rupturable membrane <NUM> may be provided in the first venting port 221A, and instead of the rupturable membrane <NUM>, a mesh <NUM> may be provided in the second venting port 221B. On the contrary, the mesh <NUM> may be provided in the first venting port 221A, and the rupturable membrane <NUM> may be provided in the second venting port 221B.

When compared with the top plate <NUM> described above, the top plate 220A according to this variation may be advantageous in reducing the venting gas pressure due to its more complicated gas venting path. Additionally, the complicated venting path and the configuration of the first venting port 221A and the second venting port 221B makes it more difficult for high temperature spark or flame to exit the pack case <NUM> together when allowing the venting gas out. Accordingly, this variation may be more advantageous than the above-described embodiment in preventing fire risks near the outside of the battery pack <NUM>.

Subsequently, a battery pack according to another embodiment of the present disclosure will be described with reference to <FIG>. The same reference numeral as the previous embodiment indicates the same element. To avoid redundancy, the overlapping description of the same element is omitted and the following description is made based on difference(s) between this embodiment and the previous embodiment.

When compared with the previous embodiment, the battery pack according to another embodiment of the present disclosure may further include an outer cover plate <NUM> configured to surround the upper area of the top plate <NUM> as shown in <FIG>.

The battery pack <NUM> of the previous embodiment may have the risk of damage caused by external forces since the rupturable membrane <NUM> on the top plate <NUM> is directly exposed to the external environment. Accordingly, the battery pack according to another embodiment of the present disclosure is configured to cover the rupturable membrane <NUM> with the outer cover plate <NUM> to protect the rupturable membrane <NUM> from external forces. The outer cover plate <NUM> may be, for example, a high strength plastic, aluminum or iron plate, and may have an air permeable structure such as, for example, a grating, to allow air to pass therethrough, where necessary.

The battery pack according to the present disclosure may be applied to a vehicle such as an electric vehicle or a hybrid electric vehicle. The battery pack may be installed in a vehicle body frame below the vehicle seat or the trunk space, and the battery pack may be installed in the vehicle with the top plate of the pack case flipped upside down where necessary.

Claim 1:
A battery pack (<NUM>), comprising:
a plurality of battery modules (<NUM>), each including battery cells (<NUM>), a module housing (<NUM>) accommodating the battery cells (<NUM>) and a gas venting channel (<NUM>) in communication with an inside of the module housing (<NUM>); and
a pack case (<NUM>) accommodating the plurality of battery modules (<NUM>), the pack case (<NUM>) including a top plate (<NUM>) to cover upper parts of the plurality of battery modules (<NUM>), the top plate (<NUM>) having a venting port (<NUM>),
wherein the gas venting channel (<NUM>) of each battery module (<NUM>) is in communication with the venting port (<NUM>),
wherein the gas venting channel (<NUM>) is disposed on the module housing (<NUM>), and
wherein the gas venting channel (<NUM>) includes a duct (<NUM>) of a hollow structure; a gas inlet (<NUM>) provided on one side of the duct (<NUM>); and a gas outlet (<NUM>) provided on the other side of the duct (<NUM>) at a predetermined distance from the gas inlet (<NUM>) in an extension direction of the duct (<NUM>),
characterized in that the gas inlet (<NUM>) matches an opening (<NUM>) of the module housing (<NUM>), and the gas outlet (<NUM>) matches the venting port (<NUM>) of the top plate (<NUM>), and
the venting port (<NUM>) includes a rupturable membrane (<NUM>) which ruptures under a predetermined pressure or above.