Patent Description:
The present invention relates to a battery pack and a device including the same, and more particularly, to a battery pack having improved safety and a device including the same.

A secondary battery which may be easily applied based on a product group and have an electrical characteristic such as high energy density or the like may be generally applied to an electric vehicle or hybrid vehicle, driven by an electric drive source, as well as a portable device, a power storage device or the like. This secondary battery has been spotlighted as a new energy source for improving eco-friendliness and energy efficiency not only for its primary advantage in which the secondary battery may significantly reduce use of a fossil fuel but also for the fact that no by-product occurs from use of energy.

A secondary battery currently commercialized may include a nickel cadmium battery, a nickel hydride battery, a nickel zinc battery and a lithium secondary battery. Among these batteries, the lithium secondary battery may be in spotlight because of having little memory effect compared to the nickel-based secondary batteries, thus having its free charging and discharging, very low self-discharge rate and high energy density.

The lithium secondary battery may mainly use a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery may include an electrode assembly in which a positive electrode plate and a negative electrode plate to which the positive electrode active material and the negative electrode active material are respectively applied are disposed while having a separator interposed therebetween, and a casing sealing and housing the electrode assembly together with an electrolyte, that is, a battery case.

In general, the lithium secondary battery may be classified into a prismatic secondary battery in which the electrode assembly is embedded in a metal can, and a pouch-type secondary battery in which the electrode assembly is embedded in a pouch of an aluminum laminate sheet, based on a type of the casing.

The secondary battery used in a small device may have two or three battery cells disposed therein. However, the secondary battery used in a medium to large-sized device such as an automobile may use a battery module in which a plurality of battery cells are electrically connected to each other. Such a battery module in which the plurality of battery cells are connected in series or parallel to each other to form a battery cell stack may have improved capacity and output. In addition, the plurality of battery modules may be mounted together with various control and protection systems such as a battery management system (BMS) and a cooling system to form a battery pack.

The battery pack may have a structure in which the plurality of battery modules are combined to each other, and the safety and operational efficiency of the battery pack may thus be problematic when some battery modules have overvoltage, overcurrent or overheating occurring therein. In particular, there is a trend in which the battery pack has a gradually increased capacity to improve a mileage. In a state where internal energy of the pack is also increased, it is thus necessary to design a structure to satisfy a strengthened safety standard and to secure safeties of a vehicle and a driver. To this end, there is an emerging need especially for a structure which may prevent internal thermal runaway or the like in advance or suppress transfer between the modules to minimize damage even when the runaway or the like occurs.

Document <CIT> relates to battery packs in which a plurality of battery modules are stacked. Document <CIT> discusses a battery arrangement in a vehicle which ensures high operational reliability under changing temperature and/or pressure conditions. Document <CIT> discusses a battery module including a release mechanism for releasing a gas from a battery to outside the case with safety. Document <CIT> a battery pack having improved safety and an automobile including the same. Document <CIT> relates to a secondary battery including an insulating plate which enables easy gas discharge and is not broken at high temperature.

An exemplary embodiment of the present invention provides a battery pack which may suppress transfer between battery modules to minimize damage even when some modules in a battery have overvoltage, overcurrent or overheating occurring therein.

However, technical problems to be solved by an exemplary embodiment of the present invention are not limited to the aforementioned problems, and may be variously expanded in the scope of a technical idea included in the present invention.

According to an exemplary embodiment of the present invention, a battery pack includes: a plurality of battery modules; a vent frame disposed along edges of the plurality of battery modules; and a housing accommodating the plurality of battery modules and the vent frame, wherein the vent frame includes a pair of vertical beams formed parallel to a first direction and a pair of horizontal beams formed parallel to a second direction intersecting the first direction, and wherein the vertical beam and the horizontal beam each have a shape of a tube and include a cover formed on the vertical beam or the horizontal beam in a length direction, and a passage surrounded by the cover for gas to pass through.

Each of the battery modules includes a battery cell stack in which a plurality of battery cells are stacked, a module frame accommodating the battery cell stack, and wherein an end plate covering the battery cell stack exposed to each of two ends of the module frame, and the end plate includes at least one vent gate formed in the shape of a tube externally protruding from the end plate and communicating with the inside of the battery module.

The cover of the horizontal beam includes at least one first connection hole opposite to one of the plurality of battery modules, and wherein the vent gate is formed opposite to the at least one first connection hole for the vent gate and the horizontal beam to communicate with each other.

The cover of any one of the vertical beam and the horizontal beam includes a second connection hole formed at a portion where the vertical beam and the horizontal beam intersect with each other and communicating with the passage of any one of the vertical beam and the horizontal beam.

The battery pack further includes at least one burst portion formed on the outside of any one of the horizontal beam and the vertical beam and connected to the passage.

The vent gate, the at least one first connection hole, the passage of the horizontal beam, the second connection hole and the passage of the vertical beam may be connected with one.

The housing may include a lower housing including a bottom surface on which the plurality of battery modules are disposed and a side wall extended upward from the bottom surface, and an upper cover covering an opening of an upper portion of the lower housing, and wherein the burst portion may be coupled to the horizontal beam or the vertical beam while having the side wall of the lower housing interposed therebetween.

The burst portion may be connected to the passage of the horizontal beam or vertical beam, and may be configured to burst when a pressure of introduced gas is a predetermined pressure or more.

The cover of the vertical beam may include a first inner cover disposed adjacent to the battery module in the second direction, and a first outer cover disposed away from the battery module in the second direction, and at least one of the first inner cover and the first outer cover may include a groove elongated in the first direction.

The first inner cover may include two second connection holes positioned at ends of one surface thereof adjacent to the battery module in the second direction, the ends being adjacent to the horizontal beam.

The groove elongated in the first direction may form the passage as the first inner cover and the first outer cover are coupled with each other.

The cover of the horizontal beam may include a second inner cover disposed adjacent to the battery module in the first direction, and a second outer cover disposed away from the battery module in the first direction, and wherein at least one of the second inner cover and the second outer cover may include a groove elongated in the second direction.

The second inner cover may include at least one first connection hole formed in one surface thereof adjacent to the battery module in the first direction.

The battery pack may include a burst portion disposed on the outside of the second outer cover in the first direction and connected to the passage of the horizontal beam, wherein the second outer cover includes at least one third connection hole for its communication with the burst portion.

The groove elongated in the second direction may form the passage as the second inner cover and the second outer cover are coupled with each other.

The exemplary embodiments of the present invention may minimize the damage because the flame is moved along the vent frame to be emitted to the outside, rather than being transferred randomly, even when some modules in the battery have the overvoltage, overcurrent or overheating occurring therein, thereby improving the safety of the battery pack.

Hereinafter, exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily practice the present invention. The present invention may be implemented in various different forms and is not limited to exemplary embodiments provided herein.

A portion unrelated to the description is omitted in order to obviously describe the present invention, and the same or similar components are denoted by the same reference numeral throughout the present specification.

In addition, the size and thickness of each component shown in the accompanying drawings are arbitrarily shown for convenience of explanation, and therefore, the present invention is not necessarily limited to contents shown in the accompanying drawings. The thicknesses are exaggerated in the drawings in order to clearly represent several layers and regions. In addition, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation.

In addition, when an element such as a layer, a film, a region or a substrate is referred to as being "on" or "above" another element, it may be "directly on" another element or may have a third element interposed therebetween. On the contrary, when an element is referred to as being "directly on" another element, there is no third element interposed therebetween. In addition, when referred to as being "on" or "above" a reference element, an element may be positioned on or below the reference element, and may not necessarily be "on" or "above" the reference element toward an opposite direction of gravity.

Further, throughout the present specification, unless especially described to the contrary, "including" any components may be understood to imply the inclusion of other elements rather than the exclusion of any other elements.

Furthermore, throughout the specification, the word "on the plane" may indicate a case where a target is viewed from the top, and the word "on the cross section" may indicate a case where a cross section of a target taken along a vertical direction is viewed from the side.

Hereinafter, the description describes a battery pack according to an exemplary embodiment of the present invention.

<FIG> is an exploded perspective view of a battery pack according to an exemplary embodiment of the present invention.

Referring to <FIG>, a battery pack <NUM> according to an exemplary embodiment of the present invention may include a plurality of battery modules <NUM> and a vent frame <NUM> disposed along edges of the battery modules <NUM>. The plurality of battery modules <NUM> and the vent frame <NUM> may be mounted on a pack tray <NUM> to be accommodated in a housing <NUM>. The housing <NUM> may include a lower housing <NUM> accommodating the pack tray <NUM>, and an upper cover <NUM> coupled to the lower housing <NUM> to cover an upper portion of the battery module <NUM>.

The plurality of battery modules <NUM> may each include a battery cell stack (not shown) disposed in a module frame <NUM>, and an end plate <NUM> covering the battery cell stack exposed to each of two ends of the module frame <NUM>. Here, either one of the two end plates <NUM> may include a vent gate <NUM> communicating with the inside of the battery module <NUM> to emit flame or heat that may occur therein. The vent gate <NUM> may be disposed in the battery pack <NUM> to face the outside of the battery pack <NUM>, and is disposed in each of the two ends of the battery pack <NUM> in a first direction (x-axis direction) to face the outside.

The vent frame <NUM> may be disposed along the edges of all of the plurality of battery modules <NUM>. The vent frame <NUM> may have a shape of a tube formed along each side of the battery pack <NUM>, and may include a pair of vertical beams <NUM> and a pair of horizontal beams <NUM>, respectively extended in the first direction (x-axis direction) and a second direction (y-axis direction) and formed to communicate with each other as a whole. A detailed configuration of the vent frame <NUM> is described below.

The plurality of battery modules <NUM> and the vent frame <NUM> may be mounted on the pack tray <NUM>, and fixed to the pack tray <NUM> by a fixing means when necessary. The battery module <NUM>, the vent frame <NUM> and the pack tray <NUM> may be accommodated in the lower housing <NUM>. The lower housing <NUM> may include a bottom surface on which the pack tray <NUM> is disposed, and a side wall extended upward from an edge of the bottom surface. The upper cover <NUM> covering the upper portion of the battery module <NUM> may be coupled to the lower housing <NUM> to protect an internal electric field. Here, the housing <NUM> may include various control and protection systems such as a battery management system (BMS) and a cooling system together with the battery module <NUM> mounted therein.

At least one burst portion <NUM> which may emit heat or flame occurring in the lower housing <NUM> to the outside may be formed on one sidewall of the lower housing <NUM>. A detailed configuration of the burst part <NUM> is described below.

Hereinafter, the vent frame of the battery pack according to an exemplary embodiment of the present invention is described in more detail.

<FIG> is an exploded perspective view of a vent frame in the battery pack according to an exemplary embodiment of the present invention.

Referring to <FIG> and <FIG>, the vent frame <NUM> may have the shape of a tube formed along each side of the battery pack <NUM>, and may include the pair of vertical beams <NUM> and the pair of horizontal beams <NUM>, respectively extended in the first direction (x-axis direction) and the second direction (y-axis direction) and formed to communicate with each other as a whole.

The vertical beam <NUM> may have the shape of a tube elongated in the first direction (x-axis direction), and here include a cover <NUM> defining the tubular-shaped inside, and a passage <NUM> formed inside the cover. The cover <NUM> may include a first inner cover 311a disposed adjacent to the battery module <NUM> in the second direction (y-axis direction), and a first outer cover 311b disposed opposite to the first inner cover 311a to be away from the battery module <NUM> in the second direction (y-axis direction). At least one of the first inner cover 311a and the first outer cover 311b may include a groove elongated in the first direction. That is, a cross section of at least one cover may have a U-shape (shape in which one surface is removed from a rectangular tube shape), and the other cover may be coupled thereto, thereby defining the passage <NUM>. However, the present invention is not limited thereto, and is not particularly limited as long as the tubular shape may be obtained by the cover <NUM>.

The horizontal beam <NUM> may have the shape of a tube elongated in the second direction (y-axis direction), and here include a cover <NUM> defining the tubular-shaped inside, and a passage <NUM> formed inside the cover. The cover <NUM> may include a second inner cover 321a disposed adjacent to the battery module <NUM> in the first direction (x-axis direction), and a second outer cover 321b disposed opposite to the second inner cover 321a to be away from the battery module <NUM> in the first direction (x-axis direction). At least one of the second inner cover 321a and the second outer cover 321b may include a groove elongated in the second direction. That is, a cross section of at least one cover may have a U-shape (shape in which one surface is removed from the rectangular tube shape), and the other cover may be coupled thereto, thereby defining the passage <NUM>. In particular, in this exemplary embodiment, both the second inner cover 321a and the second outer cover 321b may have the U-shaped cross section as shown in <FIG>, thereby allowing the horizontal beam <NUM> to have improved strength when assembled. However, the present invention is not limited thereto, and is not particularly limited as long as the tubular shape may be obtained by the cover <NUM>.

The horizontal beam <NUM> may include a first connection hole <NUM> formed in its surface opposite to the battery module <NUM>, that is, in one surface of the second inner cover 321a. The first connection hole <NUM> may be disposed to communicate with the vent gate <NUM> of the battery module <NUM> described above. In addition, the horizontal beam <NUM> may further include a third connection hole <NUM> formed in its surface disposed in a direction away from the battery module <NUM> in the second direction, that is, in one surface of the second outer cover 321b. The third connection hole <NUM> may be disposed to allow the burst portion <NUM> and passage <NUM> to communicate with each other. Here, the vent gate <NUM>, the passage <NUM> of the horizontal beam <NUM> and the burst portion <NUM> may be coupled with one another by a vent path bracket <NUM> to guide their communication path.

The vertical beam <NUM> may include second connection holes <NUM> formed at both ends of the first inner cover 311a, adjacent to the horizontal beam <NUM>. The passage <NUM> of the horizontal beam <NUM> and the passage <NUM> of the vertical beam <NUM> may communicate with each other through the second connection hole <NUM>.

The burst portion <NUM> may be connected to the passage <NUM> of the horizontal beam <NUM>, and include a burst surface <NUM> (shown in <FIG>) configured to burst when a pressure of introduced gas becomes a predetermined pressure or more. In addition, the burst portion <NUM> may include a wing portion <NUM> (shown in <FIG>) configured to protrude from a body on which the burst surface <NUM> is formed and to be coupled with the side wall of the lower housing <NUM>. The wing portion <NUM> may be fixed to the lower housing <NUM> by a fastening means such as a screw. In this exemplary embodiment, the burst portion <NUM> may be connected to the passage <NUM> of the horizontal beam <NUM>, and fixed to the horizontal beam <NUM> while having the lower housing <NUM> interposed therebetween. However, the present invention is not limited thereto, and may appropriately employ any configuration communicating with the passage of the vent frame <NUM> to enable the flame or heat to be emitted to the outside. In addition, this exemplary embodiment shows that two burst portions <NUM> are formed on only one side of the pair of horizontal beams <NUM>, and is not limited thereto. The burst portion may also be formed on the other side of the pair of horizontal beams <NUM>, or may be formed on the vertical beam <NUM>. Here, the position and number of the burst portion may be appropriately selected when necessary.

By the above configuration, the passage may be formed to communicate as a whole in the vent frame <NUM> having the rectangular shape by including the vertical beam <NUM> and the horizontal beam <NUM>. This passage may communicate with the vent gate <NUM> and burst portion <NUM> of the battery module <NUM>, and minimize an affect on neighboring battery modules by inducing heat and flame to the outside when thermal runaway occurs from the battery module <NUM>. Here, flame included in an occurring high-pressure venting gas may be entirely burned while passing through the passage in the vent frame <NUM> and emitted to the outside in a safer state. In addition, the vent frame <NUM> may serve as a support frame stably supporting the battery module <NUM> in normal times, other than when the thermal runaway occurs, thereby improving stability of the battery pack <NUM>.

Hereinafter, the description describes a path to control an issue such as overvoltage, overcurrent or overheating when the same occurs in some battery modules in the battery pack.

<FIG> is a view schematically showing a transfer path when thermal runaway occurs in some modules in the battery pack according to an exemplary embodiment of the present invention; <FIG> is an enlarged view of portion IV of <FIG>; and <FIG> and <FIG> are enlarged views of portion V of <FIG>.

Referring to <FIG>, the high-pressure venting gas may be emitted from the inside of the battery module <NUM> through the vent gate <NUM> when the (thermal) issue such as the overvoltage, overcurrent or overheating occurs in the battery module <NUM>. Here, gas and flame in high temperature and high pressure may be induced to the first connection hole <NUM> positioned closest to the vent gate <NUM> of the battery module <NUM> in which the thermal issue occurs. The gas and flame in the high temperature and high pressure, introduced through the first connection hole <NUM>, may be emitted to the outside along the passage formed in the vent frame <NUM>.

For example, when the thermal issue occurs in the battery module <NUM> disposed at position <NUM> in <FIG>, the gas and flame in the high pressure may be emitted through the vent gate <NUM> as shown in <FIG>, pass through the passage <NUM> of the horizontal beam <NUM>, and then be directly induced toward the burst portion <NUM> to be emitted to the outside. Accordingly, the thermal issue occurring in the battery module <NUM> disposed at position <NUM> may be emitted to the outside without affecting the neighboring modules.

In addition, when the thermal issue occurs in the battery module <NUM> disposed at position <NUM> in <FIG>, the gas and flame in the high temperature and high pressure may be emitted through the vent gate <NUM> to be introduced into the passage <NUM> of the horizontal beam <NUM>, as shown in <FIG> and <FIG>. Then, the gas and flame in the high temperature and high pressure introduced into the passage <NUM> of the vertical beam <NUM> through the second connection hole <NUM>, and then moved along the passage <NUM> may be induced to the horizontal beam <NUM> disposed close to the burst portion <NUM> through the second connection hole <NUM> formed at the opposite end of the corresponding vertical beam <NUM> to be finally emitted to the outside through the burst portion <NUM>. That is, when the thermal issue occurs in the battery module <NUM>, the gas and flame in the high temperature and high pressure may be induced to the passage of the vent frame <NUM> through the first connection hole <NUM> positioned closest to the vent gate <NUM> of the corresponding battery module <NUM> to be finally emitted to the outside.

According to this configuration, even when the thermal issue occurs in the battery module <NUM> positioned away from the burst portion <NUM> as shown in <FIG>, the heat and flame occurring therein may be induced outward and emitted without affecting the neighboring modules. On the other hand, in a case of the conventional battery pack <NUM> to which such a structure of the vent frame <NUM> is not applied, the venting gas (gas and flame in the high temperature and high pressure) occurring in a module <NUM> may be randomly transferred to all of modules <NUM> to <NUM>. As a result, all the modules in the battery pack <NUM> may be exposed to a risk in which a temperature rise and a series of additional thermal runaway occur therein.

As described above, an exemplary embodiment of the present invention may include the vent frame <NUM> which may serve as the support frame stably supporting the battery module <NUM> in the normal times, and induce the occurring high-pressure venting gas (gas and flame in the high temperature and high pressure) to the path in the vent frame <NUM> to stably emit the same to the outside of the battery pack <NUM> when the thermal issue occurs in the battery pack <NUM>, thereby preventing diffusion of the gas and flame to the neighboring modules.

Claim 1:
A battery pack (<NUM>) comprising:
a plurality of battery modules (<NUM>);
a vent frame (<NUM>) disposed along edges of the plurality of battery modules (<NUM>); and
a housing (<NUM>) accommodating the plurality of battery modules (<NUM>) and the vent frame (<NUM>),
wherein the vent frame (<NUM>) includes a pair of vertical beams (<NUM>) formed parallel to a first direction and a pair of horizontal beams (<NUM>) formed parallel to a second direction intersecting the first direction,
wherein the vertical beam (<NUM>) and the horizontal beam (<NUM>) each have a shape of a tube and include a cover (<NUM>, <NUM>) formed on the vertical beam (<NUM>) or the horizontal beam (<NUM>) in a length direction, and a passage (<NUM>, <NUM>) surrounded by the cover (<NUM>) for gas to pass through,
wherein each of the battery modules (<NUM>) includes a battery cell stack in which a plurality of battery cells are stacked, a module frame (<NUM>) accommodating the battery cell stack, and an end plate (<NUM>) covering the battery cell stack exposed to each of two ends of the module frame (<NUM>),
wherein the end plate (<NUM>) includes at least one vent gate (<NUM>) formed in the shape of a tube externally protruding from the end plate (<NUM>) and communicating with the inside of the battery module (<NUM>),
wherein the vent gate (<NUM>) is disposed in the battery pack (<NUM>) to face the outside of the battery pack (<NUM>), and is disposed in each of the two ends of the battery pack (<NUM>) in the first direction to face the outside,
wherein the cover (<NUM>) of the horizontal beam (<NUM>) includes at least one first connection hole (<NUM>) opposite to one of the plurality of battery modules (<NUM>),
wherein the vent gate (<NUM>) is formed opposite to the at least one first connection hole (<NUM>) for the vent gate (<NUM>) and the horizontal beam (<NUM>) to communicate with each other,
wherein the cover (<NUM>, <NUM>) of any one of the vertical beam (<NUM>) and the horizontal beam (<NUM>) includes a second connection hole (<NUM>) formed at a portion where the vertical beam (<NUM>) and the horizontal beam (<NUM>) intersect with each other and communicating with the passage (<NUM>, <NUM>) of any one of the vertical beam (<NUM>) and the horizontal beam (<NUM>), and characterized in that
the battery pack further comprises
at least one burst portion (<NUM>) formed on the outside of the horizontal beam (<NUM>) and connected to the passage (<NUM>, <NUM>).