Patent Description:
Secondary batteries are gaining attention for their primary advantage of remarkably reducing the use of fossil fuels and not generating by-products from the use of energy, making it a new eco-friendly and energy efficient source of energy.

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

In general, secondary batteries have an operating voltage of about <NUM>. 5V to <NUM>. Accordingly, electric vehicles or energy storage systems requiring large capacity and high output use battery packs as an energy source, and the battery pack includes battery modules connected in series and/or in parallel, each battery module including a plurality of secondary batteries connected in series and/or in parallel.

As secondary batteries are used as a large capacity and high output energy source, ensuring the safety of the battery modules/packs is an important issue.

The state-of-the-art battery modules are designed such that a large number of secondary batteries are densely packed to improve the energy density, and in case that a fire occurs due to a failure in one of the secondary batteries, they are prone to thermal runaway propagation to adjacent secondary batteries. By this reason, the battery modules and the battery packs include a cooling system and a fire extinguishing system. Such battery modules are disclosed in <CIT>, <CIT> and <CIT>.

Currently, when a fire occurred in a secondary battery, fire extinguishing systems configured to detect the fire using a gas sensor and feed water into the battery pack or the battery module have been developed in the corresponding industry, but they fail to stop the spread of the fire to other secondary batteries at the initial stage due to a predetermined time difference until water contacts the secondary battery in which the fire occurred for the first time since a water valve has been opened.

Meanwhile, high temperature gas generated from the secondary battery in which the fire triggers the rapid transfer of heat to other secondary batteries. However, in general, compared to air-cooled battery modules, water-cooled battery modules have an air-tight structure, so they fail to smoothly force high temperature gas out, and thermal propagation to secondary batteries occurs faster.

The present disclosure is designed to solve the above-described technical problem, and therefore the present disclosure is directed to providing a battery module for quickly feeding a coolant to a battery cell in which a fire occurred and smoothly forcing venting gas out.

The technical problem of the present disclosure to be solved is not limited to the above-mentioned problem, and these and other problems will be clearly understood by those skilled in the art from the following description.

According to the present disclosure, there is provided a battery module including a plurality of battery cells; and a module case accommodating the plurality of battery cells, wherein the module case includes an upper plate positioned on the plurality of battery cells and a lower plate positioned below the plurality of battery cells, each having a channel in which a coolant flows, the upper plate and the lower plate include a melting spot which melts when heated in a first plate in contact with the plurality of battery cells, and the upper plate includes a vent hole and a first sealing cap in a second plate which faces the first plate, the vent hole through which gas is forced out, and the first sealing cap configured to seal the vent hole and made of a thermomeltable material.

The vent hole may be provided with a mesh structure.

The vent hole may be formed over a region of the second plate along the channel.

The upper plate and the lower plate may comprise a heatsink having a channel between the first plate and the second plate.

The heatsink may include the first plate and the second plate made of aluminum (A1), or may be fabricated by dissimilar materials joining of the first plate made of aluminum (Al) and the second plate made of steel.

The melting spot may include a first melting spot in the upper plate and a second melting spot in the lower plate, and the first melting spot and the second melting spot may be arranged at vertically symmetric locations with the at least one battery cell interposed between.

The melting spot may include a through-hole in a thicknesswise direction of the first plate and a second sealing cap configured to seal the through-hole and made a thermomeltable material, and the through-hole and the second sealing cap may be provided at a predetermined interval along the channel.

The second sealing cap may include a body which is disposed in the through-hole; and a top flange and a bottom flange horizontally extended from top and bottom of the body to cover an upper surface and a lower surface of the first plate, respectively.

The top flange and the bottom flange may have at least one protrusion in a direction facing each other, and the first plate may have a groove of a shape which matches the protrusion.

The protrusion may have any one of triangular, trapezoidal, rectangular and semicircular shapes in cross section.

According to another aspect of the present disclosure, there is provided a battery pack including at least one battery module described above.

According to an aspect of the present disclosure, when a fire occurs in a certain battery cell, the sealing cap adjacent to the corresponding battery cell melts to immediately feed a coolant to the corresponding battery cell. Accordingly, it is possible to prevent thermal propagation in the battery module quickly and effectively.

Additionally, according to another aspect of the present disclosure, after the coolant of the upper plate is supplied to the battery cell in which the fire occurred, the channel of the upper plate may be used as a gas exit passage. High temperature gas may flow along the channel of the upper plate and exit through the vent hole of the upper plate.

Additionally, the vent hole is formed with a mesh structure, thereby preventing the propagation of blazing flames with the high temperature gas.

Additionally, the upper plate and the lower plate of the module case of the present disclosure comprise a heatsink. The heatsink performs a cooling function in normal condition and a fire extinguishing function in emergency. That is, the cooling system and the fire extinguishing system are operated in combination by the same component. Accordingly, it is possible to improve the energy density of the battery module, reduce the number of components and achieve cost savings.

The effects of the present disclosure are not limited to the above-mentioned 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, exemplary embodiments 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 some exemplary embodiments of the present disclosure, but not intended to fully describe the technical aspects of the present disclosure, so it should be understood that a variety of other equivalents and modifications could have been made thereto at the time that the application was filed.

A battery module <NUM> according to an embodiment of the present disclosure includes a cell stack including a plurality of battery cells <NUM> and a module case <NUM> accommodating the cell stack.

The battery cell <NUM> may include a pouch-type battery cell <NUM>. The pouch-type battery cell <NUM> is an approximately plate-shaped battery cell <NUM> including a hermetically sealed pouch-type case in which an electrode assembly and an electrolyte solution are received, and it is well known at the filing date of the present disclosure and its detailed description is omitted.

Each of the pouch-type battery cells <NUM> standing in the vertical direction (±Z) is stacked such that wide surfaces face each other in the horizontal direction (±Y) to form a cell stack. A buffer pad or a thin-film type cooling pin may be interposed between the pouch-type battery cells <NUM> to absorb swelling or transfer heat.

The battery cells <NUM> may be swollen by the expansion and contraction of the electrode assembly and gas generated as charging/discharging by-products in the repeated charging/discharging process. The battery module <NUM> may further include a barrier <NUM> of a hollow structure (see <FIG>) between the battery cells <NUM> to absorb the swelling of the battery cells <NUM> and minimize the deformation of the module case <NUM>.

As described below in detail, the battery module <NUM> of this embodiment may be configured such that each of the top edge and bottom edge of the pouch-type battery cells <NUM> is secured to the module housing with a thermally conductive adhesive and a coolant W1 is brought into indirect contact with the battery cells <NUM> to cool the battery cells <NUM>.

Meanwhile, although this embodiment shows the pouch-type battery cells <NUM>, cylindrical or prismatic battery cells <NUM> may be used as an alternative to the pouch-type battery cells.

The module case <NUM> may be made of a material having high mechanical strength to receive the cell stack and protect it from the external impacts or vibrations and may be approximately in the shape of a six-sided box. For example, as shown in <FIG>, the module case <NUM> of this embodiment may be formed in the shape of a six-sided box including an upper plate <NUM> positioned on the cell stack, a lower plate <NUM> positioned below the cell stack and a wall frame <NUM> disposed around the cell stack. Although briefly shown, the wall frame may be an assembly of four plates including front/rear cover plates that cover the front side and the rear side of the cell stack and a pair of side plates that cover the sides of the cell stack.

In particular, in the module case <NUM> of the present disclosure, the upper plate <NUM> and the lower plate <NUM> comprise a heatsink to effectively cool the battery cells <NUM> in a normal condition and stop fires in the battery cells <NUM> quickly in emergency. Here, the heatsink refers to a cooling component having a channel in which the coolant W1 flows to absorb heat.

In general, in the case of the conventional water-cooled battery module, the heatsink is a separate component from the module case and is positioned below the lower plate of the module case. However, the battery module <NUM> according to this embodiment includes the module case <NUM> integrally formed with the heatsink, and the upper plate <NUM> and the lower plate <NUM> of the module case <NUM> correspond to the heatsink. By this configuration of the module case <NUM>, it is possible to reduce the path along which heat from each battery cell <NUM> is transferred to the heatsink, reduce the number of heat transfer components and increase the energy density of the battery module <NUM>.

The structure of the upper plate <NUM> and the lower plate <NUM> of the module case <NUM> and the battery module <NUM> for the cooling and fire extinguishing of the battery cells <NUM> will be described below in detail with reference to <FIG>.

Referring to <FIG>, the upper plate <NUM> of the module case <NUM> may be a heatsink including a first plate <NUM> and a second plate <NUM>, and a channel F between the first plate <NUM> and the second plate <NUM>. The lower plate <NUM> of the module case <NUM> may be the same as the upper plate <NUM> except a vent hole <NUM> as described below.

The first plate <NUM> may be positioned in contact with the battery cells <NUM> and made of aluminum (Al) having high thermal conductivity, and the second plate <NUM> may be made of steel having high stiffness. The first plate <NUM> and the second plate <NUM> of dissimilar materials may be joined, for example, by braze welding.

As the heatsink is fabricated by dissimilar materials joining of the aluminum first plate <NUM> and the steel second plate <NUM>, it is possible to prevent damage such as perforation in the outer side of the heatsink by high temperature gas and particles. However, the scope of protection of the present disclosure is not limited to the heatsink fabricated by dissimilar materials joining of aluminum and steel. That is, in the fabrication of the heatsink, for easy fabrication process and light weight, both the first plate <NUM> and the second plate <NUM> may be made of aluminum or any other material having light weight and high stiffness may be used.

The channel F may be defined as a sealed space created by joining the second plate <NUM> having a convex pattern shown in <FIG> on one surface of the flat first plate <NUM>. An inlet port P1 and an outlet port P2 may be detachably connected to one side and the other side of the channel F, respectively.

The coolant W1 may be supplied to the channel F through the inlet port P1 and exit through the outlet port P2. Although this embodiment describes the inlet port P1 and the outlet port P2 installed at both the upper plate <NUM> and the lower plate <NUM>, for example, the upper plate <NUM> may be filled with the coolant W1 and the inlet port P1 and the outlet port P2 may not be connected. In this case, the upper plate <NUM> may be used like a water tank that stores a predetermined amount of coolant W1.

By the above-described configuration, heat generated from the battery cells <NUM> may be dissipated through two paths. That is, the heat of the battery cells <NUM> may be transferred in an order of "the top edge of the battery cells <NUM> => the aluminum first plate <NUM> of the upper plate <NUM> => the coolant W1" and "the bottom edge of the battery cells <NUM> => the aluminum first plate <NUM> of the lower plate <NUM> => the coolant W1". Accordingly, the battery module <NUM> of the present disclosure may be effective in quickly lowering the temperature of the battery cells <NUM> overheated by charging/discharging.

Additionally, to stop the propagation of a fire occurring in one or some of the battery cells <NUM> to the adjacent battery cells <NUM>, the upper plate <NUM> and the lower plate <NUM> of the module case <NUM> according to the present disclosure have a melting spot in the first plate <NUM>. The melting spot refers to a region of the first plate <NUM> that melts when heated.

The melting spot may include a first melting spot in the upper plate <NUM> and a second melting spot in the lower plate <NUM>, and the first melting spot and the second melting spot may be arranged at vertically symmetric locations with at least one battery cell <NUM> interposed between.

More specifically, referring to <FIG> and <FIG>, the first melting spot may include a through-hole <NUM> in the thicknesswise direction of the first plate <NUM> and a second sealing cap <NUM> made of a thermomeltable material. The through-hole <NUM> and the second sealing cap <NUM> may be provided at a predetermined interval along the channel F in the upper plate <NUM>.

In the same way as the first melting spot, the second melting spot may include a through-hole and a second sealing cap <NUM>, and may be provided at a predetermined interval along the channel F in the lower plate <NUM>.

As shown in <FIG>, the second sealing cap <NUM> may include a body 213a which is disposed in the through-hole <NUM> and a top flange 213b and a bottom flange 213c horizontally extended from the top and bottom of the body 213a to cover an upper surface and a lower surface of the first plate <NUM>, respectively.

Additionally, the top flange 213b and the bottom flange 213c may have at least one protrusion 213d in a direction facing each other and the first plate <NUM> may have a groove of a shape that matches the protrusion 213d. In particular, the protrusion 213d may be in a knife edge shape, i.e., a triangular shape in cross section. In addition to the knife edge shape of this embodiment, for example, the protrusion 213d may be in trapezoidal, rectangular and semicircular shapes.

In this embodiment, the protrusion 213d of the knife edge shape is applied to the top flange 213b and the bottom flange 213c to enhance the sealability and the coupling strength of the second sealing cap <NUM>.

The material of the second sealing cap <NUM> may include a plastic resin such as polyethylene (PE) or polypropylene (PP). For example, the plastic second sealing cap <NUM> and the aluminum first plate <NUM> may be integrally formed by insert molding. Meanwhile, the scope of protection of the present disclosure is not limited to the second sealing cap <NUM> made of the plastic material. That is, the second sealing cap <NUM> may be made of any other material, for example, rubber having thermomeltability and sealability.

<FIG> is a diagram illustrating the cooling structure of the battery module <NUM> according to an embodiment of the present disclosure.

In the battery module <NUM> according to this embodiment, the through-hole <NUM> of the first plate <NUM> is sealed by the second sealing cap <NUM> in normal condition as shown in <FIG>. Accordingly, the coolant W1 of the upper plate <NUM> and the lower plate <NUM> does not permeate into the battery cells <NUM> through the through-hole <NUM> and absorbs the heat of the battery cells <NUM> while the coolant W1 flows along the channel F.

As described above, the first plate <NUM> is made of aluminum to transfer the heat of the battery cells <NUM> to the coolant W1 fast. To increase the heat transfer rate, a heat transfer material <NUM> may be positioned on one surface of the first plate <NUM> in contact with the battery cells <NUM> or a space between the edge of the battery cells <NUM> and one surface of the first plate <NUM> may be filled with a thermally conductive resin.

<FIG> is a diagram illustrating a fire extinguishing situation when a fire occurs in the specific battery cell <NUM> in the battery module <NUM> according to an embodiment of the present disclosure.

When the temperature of a certain battery cell <NUM> among the battery cells <NUM> is abnormally high or a fire occurs, the second sealing cap <NUM> disposed on and below the corresponding battery cell <NUM> may melt by heat and high temperature gas or sparks generated from the corresponding battery cell <NUM> as shown in <FIG>. Accordingly, the second sealing cap <NUM> may cease to exist and the coolant W1 of the upper plate <NUM> may be immediately fed into the corresponding battery cell <NUM> through the opened through-hole <NUM> in the channel F.

In other words, when the second sealing cap <NUM> disposed on the battery cell <NUM> in which the fire occurred melts, the coolant W1 may be fed directly from above the corresponding battery cell <NUM>. Accordingly, it is possible to stop the fire occurred in the battery cell <NUM> quickly and prevent thermal propagation to the adjacent battery cells <NUM>.

<FIG> is a diagram illustrating a gas exit situation of the specific battery cell <NUM> in the battery module <NUM> according to an embodiment of the present disclosure.

High temperature gas generated from the battery cell <NUM> in which the fire occurred and blazing flames with the gas may be the cause of fire propagation. To protect the adjacent battery cells <NUM> from the high temperature gas and flames, the module case <NUM> according to this embodiment has the vent hole <NUM> in the second plate <NUM> of the upper plate <NUM> as shown in <FIG>.

More specifically, referring to <FIG> and <FIG> together, at least one vent hole <NUM> may be formed over a region of the second plate <NUM> along the channel F.

In particular, the vent hole <NUM> may be provided with a mesh structure. The vent hole <NUM> of this embodiment is formed by processing a region of the second plate <NUM> into a mesh structure. In an alternative example of the vent hole <NUM>, an opening may be formed in the second plate <NUM> and a mesh or a cover of a mesh structure may be installed in the opening.

As shown in <FIG> and <FIG>, the vent hole <NUM> may be sealed by a first sealing cap <NUM> made of a thermomeltable material. Accordingly, in the case of the battery module <NUM> in normal condition, the vent hole <NUM> is closed, so the coolant W1 in the channel F does not leak out of the module case <NUM>. Additionally, there is no risk that impurities from the outside of the module case <NUM> go into the vent hole <NUM>.

However, in case that a fire occurs in the battery cell <NUM>, when the coolant W1 is fed into the battery cell <NUM> through the through-hole <NUM> from the channel F of the upper plate <NUM> as shown in <FIG>, an empty space is formed in the channel F of the upper plate <NUM>. The channel F of the upper plate <NUM> at that time may be used as a gas exit path. The high temperature gas and flames move along the channel F of the upper plate <NUM> through the opened through-hole <NUM> and melt the first sealing cap <NUM>. After the first sealing cap <NUM> ceases to exist, when the vent hole <NUM> is opened, the high temperature gas may be forced out through the vent hole <NUM> at a high speed by a pressure difference between the inside and outside of the module case <NUM>. In this instance, the flames or sparks may cease to exist as the temperature becomes lower while the flames or sparks move along the channel F or may be filtered out by the vent hole <NUM> of the mesh structure. Accordingly, it is possible to prevent the propagation of flames or sparks and quickly force gas out.

Subsequently, a variation of this embodiment will be described with reference to the accompanying drawings.

<FIG> is a diagram showing a variation of the upper plate <NUM> of the module case <NUM> of <FIG>, and <FIG> and <FIG> are diagrams showing variations of the second sealing cap <NUM> of <FIG>.

The same reference number as the previous drawings indicates the same element, and an overlapping description of the same element is omitted and it will be briefly described based on different(s) between this embodiment and the above-described embodiment.

Referring to <FIG>, the upper plate 210A of the module case <NUM> according to this variation has the vent hole <NUM> extended in the lengthwise direction longer than the vent hole <NUM> of <FIG>. It is possible to force a large amount of gas out more smoothly and quickly by expanding the vent hole <NUM>.

Subsequently, <FIG> and <FIG> are diagrams showing variations of the second sealing cap <NUM>, respectively, and as shown in <FIG> and <FIG>, the shape, number and position of the protrusion 213d may be variously provided for the optimized sealing area and the enhanced coupling strength between the second sealing cap <NUM> and the first plate <NUM>.

By the components and operation of the battery module <NUM> according to the present disclosure as described hereinabove, the cooling performance of the battery cells <NUM> is very good, and when a fire occurs in the battery cell <NUM>, the coolant W1 may be immediately fed into the corresponding battery cell <NUM>, thereby effectively preventing thermal propagation in the battery module <NUM>. Additionally, gas, flames and sparks generated from the battery cell <NUM> in which the fire occurred may be guided by the channel F of the upper plate <NUM>, and gas may be forced out while preventing the spread of flames and sparks.

Meanwhile, a battery pack (not shown) according to the present disclosure may include at least one battery module. In addition to the battery module, the battery pack may further include a pack case (not shown) accommodating the battery module and a variety of devices (not shown) for controlling the charge/discharge of the battery module, for example, a Battery Management System (BMS), a current sensor, a fuse or the like.

While the present disclosure has been hereinabove described with regard to a limited number of embodiments and drawings, the present disclosure is not limited thereto and a variety of modifications and changes may be made thereto by those skilled in the art within the scope of the appended claims.

Claim 1:
A battery module (<NUM>), comprising:
a plurality of battery cells (<NUM>); and
a module case (<NUM>) accommodating the plurality of battery cells (<NUM>),
wherein the module case (<NUM>) includes:
an upper plate (<NUM>) positioned on the plurality of battery cells (<NUM>) and a lower plate (<NUM>) positioned below the plurality of battery cells (<NUM>), each having a channel (F) in which a coolant (W1) flows,
characterized in that
the upper plate (<NUM>) and the lower plate (<NUM>) include a melting spot which melts when heated in a first plate (<NUM>) in contact with the plurality of battery cells (<NUM>), and
in that
the upper plate (<NUM>) includes a vent hole (<NUM>) and a first sealing cap (<NUM>) in a second plate (<NUM>) which faces the first plate (<NUM>), the vent hole (<NUM>) through which gas is forced out, and the first sealing cap (<NUM>) configured to seal the vent hole (<NUM>) and made of a thermomeltable material.