Patent Description:
In a battery module that includes a plurality of battery cells, if an abnormality such as a short circuit occurs in some battery cells to raise temperature continuously so that the temperature of the battery cell exceeds a critical temperature, a thermal runaway phenomenon occurs. If a thermal runaway phenomenon occurs in some battery cells as described above, safety issues may be generated.

If a flame or the like is generated due to the thermal runaway phenomenon occurring in some battery cells, the flame rapidly raises the temperature of adjacent battery cells, and thus the thermal runaway phenomenon may be propagated to adjacent cells within a short time.

Eventually, if the thermal runaway phenomenon occurring in some battery cells is not quickly responded, it may lead to disasters such as ignition and explosion of a battery module or a battery pack, which is a battery unit with a greater capacity than the battery cell, and this may not only result in property damage but also cause safety problems.

Thus, if a flame occurs due to the thermal runaway phenomenon in some battery cells inside the battery module, it is urgently necessary to block air supplied to the flame to prevent the flame from spreading further. In addition, it is also important to lower the inner pressure of the battery module by quickly discharging the gas discharged by venting of the battery cell to the outside of the battery module.

In particular, a battery module adopting an air-cooled structure must have a structure capable of allowing an air to flow smoothly from the outside of the battery module to the inside thereof. A battery module adopting an air-cooled structure is disclosed in <CIT>. Therefore, there is a demand to develop a battery module having a structure capable of quickly discharging a venting gas generated therein to the outside while completely blocking the air introduced therein when a thermal runaway phenomenon occurs inside the battery module.

The present invention is designed to solve the problems of the related art, and therefore the present invention is directed to providing a battery module having a structure capable of quickly discharging a venting gas generated therein to the outside while completely blocking the air introduced therein in order to prevent the flame from spreading further when a thermal runaway phenomenon occurs inside the battery module.

However, the technical problem to be solved by the present invention is not limited to the above, and other objects not mentioned herein will be understood from the following description by those skilled in the art.

According to the present invention, there is provided a battery module, comprising: a cell stack having a plurality of battery cells; a module case configured to accommodate the cell stack; a pair of module covers configured to cover openings at both sides of the module case; and a ventilation unit installed through the module cover, wherein the ventilation unit includes: a one-way venting valve disposed at a center of a perforation hole formed through the module cover; a first hole sealing portion attached onto an inner wall of the perforation hole; and a second hole sealing portion attached onto an outer circumference of the one-way venting valve.

The first hole sealing portion and the second hole sealing portion are expanded at a reference temperature or above to meet each other so that the perforation hole is sealed.

The first hole sealing portion and the second hole sealing portion may be made of a sheet containing at least one of an epoxy-based resin, a butyl-based resin and a vinyl chloride-based resin.

The one-way venting valve may discharge a venting gas from an inside thereof to the outside when a pressure inside the module case is a reference pressure or above.

The ventilation unit may include a valve support configured to traverse the perforation hole, and the one-way venting valve may be fixed to the valve support.

The battery module may further comprise a case sealing portion attached onto an inner edge of the module case and a border area where an inner surface of the module case meets the module cover.

The case sealing portion may be expanded at a reference temperature or above to reinforce airtightness of the module case.

The one-way venting valve may include a lower cap having at least one first flow path; an upper cap having at least one second flow path and coupled to an upper portion of the lower cap to form an inner space; and a flow path cover located in the inner space and installed to cover the second flow path as being elastically pressed from the upper cap toward the lower cap.

The one-way venting valve may be made of an elastic material and has a funnel shape having an inner space gradually narrowed outward from an inner side of the module case so that facing surfaces at a top end thereof are in contact with each other.

Meanwhile, a battery pack according to an embodiment of the present invention includes a plurality of battery modules according to an embodiment of the present invention as described above.

According to one aspect of the present invention, the battery module having a air-cooled structure may quickly discharge a venting gas generated therein to the outside while completely blocking the air introduced therein in order to prevent the flame from spreading further when a thermal runaway phenomenon occurs therein, thereby securing the safety of the battery module in use.

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

Prior to the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, 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 claims.

Referring to <FIG> and <FIG>, a battery module according to an embodiment of the present invention includes a cell stack <NUM>, a module case <NUM>, a case sealing portion <NUM>, a module cover <NUM>, and a ventilation unit <NUM>.

Referring to <FIG>, the cell stack <NUM> is formed by stacking a plurality of battery cells <NUM>. As the battery cell <NUM>, for example, a pouch-type battery cell may be applied.

Referring to <FIG> along with <FIG> and <FIG>, the module case <NUM> has an approximately rectangular parallelepiped shape with openings at both longitudinal sides thereof. The module case <NUM> may be made of a metal material such as aluminum to secure rigidity.

The module case <NUM> may include an upper plate for covering an upper portion of the cell stack <NUM>, a lower plate for covering a lower portion of the cell stack <NUM>, and side plates for covering both sides of the cell stack <NUM>. The coupling between the upper plate and the side plate and the coupling between the lower plate and the side plate may be performed by welding.

Referring to <FIG> along with <FIG> and <FIG>, the case sealing portion <NUM> is attached on a border area where an inner edge of the module case <NUM> and an inner surface of the module case <NUM> meet the module cover <NUM>. That is, the case sealing portion <NUM> is attached on a border area where the upper plate and the side plate of the module case <NUM> meet, a border area where the lower plate and the side plate meet, and a periphery of the inner surface of the opening of the module case <NUM>.

The case sealing portion <NUM> is expanded at a reference temperature or above to enhance the airtightness of the module case <NUM>. If a problem such as a short circuit occurs in some of the plurality of battery cells <NUM> disposed inside the battery module and thus a temperature rises to cause a thermal runaway, it is necessary to completely block the introduction of an external air so that the flame is not propagated to neighboring cells. Since the case sealing portion <NUM> is disposed at a weak region of the module case <NUM> and expanded at or above the reference temperature at which a thermal runaway phenomenon occurs, the airtightness of the battery module is reinforced.

To perform this function, the case sealing portion <NUM> may be made of a sheet containing at least one of an epoxy-based resin, a butyl-based resin and a vinyl chloride-based resin. However, the component of the case sealing portion <NUM> is just exemplary, and any component may be applied thereto without limitation as long as it expands at the reference temperature or above to enhance airtightness.

Referring to <FIG>, the module cover <NUM> covers the openings at both longitudinal sides of the module case <NUM> and has a shape corresponding to the opening. The module cover <NUM> may also be made of a metal material for coupling with the module case <NUM> made of a metal material, and may be coupled with the module case <NUM> by welding.

As described above, since the case sealing portion <NUM> is also installed on the border area where the module case <NUM> and the module cover <NUM> meet, when the temperature inside the battery module rises to the reference temperature or above, the airtightness of the coupling portion of the module case <NUM> and the module cover <NUM> may be ensured.

Referring to <FIG> along with <FIG> and <FIG>, the ventilation unit <NUM> is installed on one longitudinal side of the module cover <NUM>, and the ventilation units <NUM> installed at the pair of module covers <NUM> are located at opposite sides. The ventilation unit <NUM> includes a perforation hole H, a valve support <NUM>, a one-way venting valve <NUM>, a first hole sealing portion <NUM> and a second hole sealing portion <NUM>.

The perforation hole H is formed through one longitudinal side of the module cover <NUM>, and functions as an air passage for cooling the battery cells <NUM> located inside the battery module when the battery module is in a normal use state. That is, if the perforation hole H formed at one longitudinal side of the battery module functions as an inlet, the perforation hole H located at the opposite side serves as an outlet.

The valve support <NUM> traverses the perforation hole H, and the one-way venting valve <NUM> is installed at a longitudinal center thereof. That is, the valve support <NUM> is a component provided for fixing the one-way venting valve.

The one-way venting valve <NUM> is fixedly installed at the center of the valve support <NUM> in the longitudinal direction, and when the inner pressure of the battery module rises to a reference pressure or above due to the gas generated by venting of the battery cell <NUM>, the gas is discharged from the inside of the battery module to the outside. That is, the one-way venting valve <NUM> blocks the introduction of air from the outside of the battery module, and is opened to discharge gas only from the inside to the outside only when the inner pressure increases. Examples of the specific structure of the one-way venting valve <NUM> will be described in detail later with reference to <FIG>.

The first hole sealing portion <NUM> is attached around an inner wall of the perforation hole H. The second hole sealing portion <NUM> is attached on an outer circumference of the one-way venting valve. According to the invention, the first hole sealing portion <NUM> and the second hole sealing portion <NUM> are expanded at the reference temperature or above to meet each other, thereby sealing the perforation hole H.

To perform this function, the first hole sealing portion <NUM> and the second hole sealing portion <NUM> may be made of a sheet containing at least one of an epoxy resin, a butyl resin and a vinyl chloride resin, similar to the case sealing portion <NUM> described above. However, the materials of the first hole sealing portion <NUM> and the second hole sealing portion <NUM> are just examples, and various materials may be applied without limitation as long as they are capable of expanding at a reference temperature or above to seal the perforation hole H.

As shown in <FIG>, if the first hole sealing portion <NUM> and the second hole sealing portion <NUM> are expanded to seal the perforation hole H, the air may not be introduced from the outside of the battery module any longer, and thus the flame does not spread due to a thermal runaway. In addition, if the gas leaked from the battery cell <NUM> increases inside the module case <NUM> due to the increase in temperature and thus the inner pressure of the battery module increases to the reference pressure or above, the one-way venting valve <NUM> is opened to discharge the gas, thereby preventing the battery module from exploding due to the increase in the inner pressure of the battery module.

As described above, since the battery module according to an embodiment of the present invention includes the sealing portions <NUM>, <NUM>, <NUM>, which are expanded to seal the battery module when the internal temperature rises, and the one-way venting valve <NUM>, which may discharge gas only from the inside to the outside as the internal pressure increases, it is possible to completely block the introduction of air from the outside in the event of a thermal runaway and quickly discharge the gas therein to the outside, thereby eliminating the risk of ignition/explosion.

Next, an exemplary structure of the one-way venting valve <NUM> applied to the present invention will be described with reference to <FIG>.

First, referring to <FIG>, one embodiment of the one-way venting valve <NUM> is illustrated. According to this embodiment, the one-way venting valve <NUM> may be a unidirectional valve including a lower cap <NUM> having at least one first flow path 421a, an upper cap <NUM> having at least one second flow path 422a, a flow path cover <NUM>, and an elastic pressing member <NUM>.

The upper cap <NUM> is formed at an upper portion of the lower cap <NUM> to form an inner space S. The flow path cover <NUM> is located in the inner space S and is elastically pressed from the upper cap <NUM> toward the lower cap <NUM> by the elastic pressing member <NUM> such as a spring to cover the first flow path 421a.

If the inner pressure of the battery module increases to the reference pressure or above, the flow path cover <NUM> compresses the elastic pressing member <NUM> to release the sealed state of the first flow path 421a, and the gas inside the battery module is discharged to the outside of the battery module through the inner space S and the second flow path 422a (see an arrow in <FIG>).

Next, referring to <FIG>, another embodiment of the one-way venting valve <NUM> is shown. According to this embodiment, the one-way venting valve <NUM> is made of an elastic material such as rubber, and has a funnel shape whose inner space is gradually narrowed outward from the inside of the battery module so that facing surfaces at a top end thereof (referring to an upper end when viewed with reference to <FIG>) are in contact with each other. At a bottom end of the one-way venting valve <NUM> (referring to a lower end when viewed with reference to <FIG>), facing surfaces thereof are spaced apart from each other.

If the inner pressure of the battery module increases to the reference pressure or above, the sealed state of the battery module is released as the top end of the elastic material of the one-way venting valve <NUM> is opened, and the gas inside the battery module is discharged to the outside along an arrow depicted in <FIG>.

Claim 1:
A battery module, comprising:
a cell stack (<NUM>) having a plurality of battery cells (<NUM>);
a module case (<NUM>) configured to accommodate the cell stack (<NUM>);
a pair of module covers (<NUM>) configured to cover openings at both sides of the module case (<NUM>); and
a ventilation unit (<NUM>) installed through the module cover (<NUM>),
characterized in that the ventilation unit (<NUM>) includes:
a one-way venting valve (<NUM>) disposed at a center of a perforation hole (H) formed through the module cover (<NUM>);
a first hole sealing portion (<NUM>) attached onto an inner wall of the perforation hole (H); and
a second hole sealing portion (<NUM>) attached onto an outer circumference of the one-way venting valve (<NUM>),
wherein the first hole sealing portion (<NUM>) and the second hole sealing portion (<NUM>) are expanded at a reference temperature or above to meet each other so that the perforation hole (H) is sealed.