Patent Publication Number: US-2023155241-A1

Title: Battery module, battery pack, and vehicle including same

Description:
TECHNICAL FIELD 
     The present disclosure relates to a battery module, a battery pack and a vehicle including the same, and more particularly, to a battery module with improved stability against fire or explosion, a battery pack and a vehicle including the same. The present application claims priority to Korean Patent Application No. 10-2020-0121769 filed on Sep. 21, 2020 in the Republic of Korea, the disclosures of which are incorporated herein by reference. 
     BACKGROUND ART 
     In recent years, the demand for portable electronic products such as notebooks, video cameras, mobile phones, or the like is rapidly increasing, and the development of electric vehicles, energy storage batteries, robots, satellites, or the like is in earnest. For this reason, high-performance secondary batteries enabling repeated charging and discharging are being actively researched. 
     Secondary batteries commercialized at the present include nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries are in the spotlight due to advantages such as free charging and discharging by little memory effect compared to nickel-based secondary batteries, and very low self-discharge rate and high energy density. 
     The lithium secondary battery mainly uses a lithium-based oxide and a carbon material as a positive electrode active material and a negative electrode active material, respectively. Also, the lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate respectively coated with the positive electrode active material and the negative electrode active material are disposed with a separator being interposed therebetween, and an exterior, namely a battery case, for hermetically storing the electrode assembly together with an electrolyte. 
     In addition, the lithium secondary battery may be classified depending on the exterior shape into a can-type secondary battery in which an electrode assembly is included in a metal can and a pouch-type secondary battery in which an electrode assembly is included in a pouch made of an aluminum laminate sheet. 
     In particular, the demand for large-capacity battery modules applied to electric vehicles or the like is increasing recently. Such a large-capacity battery module includes a plurality of battery cells. Thus, when a fire or explosion occurs in a part of the plurality of battery cells, high-temperature fragments of the electrode assembly, flames, and high-temperature gas are discharged to adjacent other battery cells to increase the temperature thereof. Accordingly, thermal runaway, fire, or the like may be propagated to adjacent other battery cells to cause a secondary explosion, thereby increasing the damage. 
     DISCLOSURE 
     Technical Problem 
     The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to providing a battery module with improved stability against fire or explosion, a battery pack and a vehicle including the same. 
     These and other objects and advantages of the present disclosure may be understood from the following detailed description and will become more fully apparent from the exemplary embodiments of the present disclosure. Also, it will be easily understood that the objects and advantages of the present disclosure may be realized by the means shown in the appended claims and combinations thereof. 
     Technical Solution 
     In one aspect of the present disclosure, there is provided a battery module, comprising: 
     a plurality of battery cells, each having electrode terminals respectively provided at an upper portion and a lower portion thereof; 
     a connection plate having electric conductivity to electrically connect the plurality of battery cells, the connection plate including a body portion extending in a horizontal direction and a connection portion extending from the body portion to contact the electrode terminal; and 
     a module case configured such that the connection plate is mounted to an outer side thereof, the module case being configured to accommodate the plurality of battery cells therein, the module case including a plurality of exposure holes configured to expose the electrode terminals of each of the plurality of battery cells to the outside and a cover portion configured to protrude toward the connection plate from an outer circumference of the exposure hole. 
     Also, the cover portion may have a hollow and be shaped to be opened in at least a top end thereof. 
     In addition, the cover portion may include a bending part bent at the protruding end of the cover portion to extend in a horizontal direction to hide a part of the exposure hole of the module case. 
     Also, the connection plate may include a plurality of connection holes formed by opening a part of the body portion so that the connection portion is located in the opening thereof, and 
     the cover portion may be configured such that the open end thereof is inserted into the connection hole. 
     Moreover, the connection plate may include an extension portion configured to extend from the connection hole toward the battery cell to screen an internal material ejected from the battery cell. 
     In addition, the battery module may further comprise a heat conduction pad having thermal conductivity and mounted to an outer side of the connection plate, the heat conduction pad having a plurality of communication holes configured to communicate with the connection hole. 
     Further, the communication hole may be formed relatively smaller than the opening size of the connection hole. 
     Also, the heat conduction pad may include two or more screen portions respectively configured to extend toward a center of the communication hole from an outer circumference of the communication hole to screen an internal material ejected from the battery cell, the two or more screen portions being located to be spaced apart from each other. 
     In addition, in another aspect of the present disclosure, there is also provided a battery pack, comprising at least one battery module as above. 
     Moreover, in another aspect of the present disclosure, there is also provided a vehicle, comprising at least one battery module as above. 
     Advantageous Effects 
     According to an embodiment of the present disclosure, the module case included in the battery module according to the present disclosure includes the cover portion protruding from the outer circumference of the exposure hole toward the connection plate. This structure may physically block the movement of a high-temperature active material discharged from the exploded battery cell to adjacent battery cells while maintaining the function of ejecting, namely venting, the gas and flame generated when the battery cell is ignited. By doing so, when the battery cell behaves abnormally to explode so that the internal material is ejected, gas and flame are ejected through the exposure hole, but the movement of the high-temperature active material is suppressed by the cover portion. Therefore, it is possible to prevent the internal material from moving to other adjacent battery cells through other exposure holes. Therefore, it is possible to prevent chain ignition, such as propagating of thermal runaway, fire or explosion to other battery cells. Accordingly, the present disclosure may greatly improve the safety. 
    
    
     
       DESCRIPTION OF DRAWINGS 
       The accompanying drawings illustrate a preferred embodiment of the present disclosure and together with the foregoing disclosure, serve to provide further understanding of the technical features of the present disclosure, and thus, the present disclosure is not construed as being limited to the drawing. 
         FIG.  1    is a perspective view schematically showing a battery module according to an embodiment of the present disclosure. 
         FIG.  2    is an exploded perspective view schematically showing the battery module according to an embodiment of the present disclosure. 
         FIG.  3    is a sectional view schematically showing a battery cell of the battery module according to an embodiment of the present disclosure. 
         FIG.  4    is a partial vertical sectional view schematically showing a part of the battery module of  FIG.  1   , cut in a front and rear direction. 
         FIG.  5    is a partial sectional view schematically showing a battery module according to another embodiment of the present disclosure. 
         FIG.  6    is a partial sectional view schematically showing a part of a battery module according to still another embodiment of the present disclosure. 
         FIG.  7    is a partial sectional view schematically showing a part of a battery module according to still another embodiment of the present disclosure. 
         FIG.  8    is a partial sectional view schematically showing a part of a battery module according to still another embodiment of the present disclosure. 
         FIG.  9    is a vertical sectional view schematically showing a part of the battery module according to still another embodiment of the present disclosure. 
     
    
    
     MODES OF PRACTICE 
     Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 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 disclosure 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 disclosure, so it should be understood that other equivalents and modifications could be made thereto without departing from the scope of the disclosure. 
       FIG.  1    is a perspective view schematically showing a battery module according to an embodiment of the present disclosure.  FIG.  2    is an exploded perspective view schematically showing the battery module according to an embodiment of the present disclosure. Also,  FIG.  3    is a sectional view schematically showing a battery cell of the battery module according to an embodiment of the present disclosure. 
     Referring to  FIGS.  1  to  3   , a battery module  100  according to an embodiment of the present disclosure includes a plurality of battery cells  110 , a connection plate  120 , and a module case  130 . 
     Specifically, the battery cell  110  may include an electrode assembly  116 , a battery can  112 , and a cap assembly  113 . For example, the battery cell  110  may be a cylindrical battery cell. In addition, the battery cell  110  may include electrode terminals  111  respectively located at an upper portion and a lower portion thereof The plurality of battery cells  110  may be electrically connected by a connection plate  120  having a metal material. The plurality of battery cells  110  may be electrically connected in series, in parallel, or in series and in parallel, through the connection plate  120 . 
     The electrode assembly  116  may have a wound structure with a separator being interposed between a positive electrode plate and a negative electrode plate. A positive electrode tab  114  may be attached to the positive electrode plate and connected to the cap assembly  113 , a negative electrode tab  115  may be attached to the negative electrode plate and connected to a lower end of the battery can  112 . 
     The battery can  112  may have an empty space so that the electrode assembly  116  may be accommodated therein. In particular, the battery can  112  may be configured in a cylindrical shape with an open top end. In addition, the battery can  112  may be made of a metal material such as steel or aluminum to secure rigidity. In addition, the negative electrode tab may be attached to the bottom of the battery can  112 , such that not only the lower portion of the battery can  112  but also the battery can  112  itself may function as a negative electrode terminal. 
     The cap assembly  113  may be coupled to the open top end of the battery can  112  to seal the open top end of the battery can  112 . The cap assembly  113  may have a circular or rectangular shape depending on the shape of the battery can  112 , and may include sub-components such as a top cap C 1 , a vent unit C 2 , and a gasket C 3 . 
     Here, the top cap C 1  may be located at an uppermost portion of the cap assembly  113  and configured to protrude upward. In particular, the top cap C 1  may function as a positive electrode terminal in the battery cell  110 . Accordingly, the top cap C 1  may be electrically connected to an external device, for example another battery cell  110  or a charging device, through the connection plate  120  or the like. The top cap C 1  may be made of, for example, a metal material such as stainless steel or aluminum. If a severe explosion or fire occurs at the battery cell  110 , at least a part of the top cap C 1  may be torn or detached from the battery can  112 , thereby opening the battery can  112 . 
     In addition, the vent unit C 2  may be configured to be deformed (ruptured) when the internal pressure of the battery cell  110 , namely the internal pressure of the battery can  112 , increases over a predetermined level, so that the gas inside the battery can  112  may be discharged to the outside through an opening D of the top cap C 1 . Here, the predetermined level of the internal pressure may be 5 to 10 atmospheres. 
     Moreover, the gasket C 3  may be made of a material with electrical insulation so that edge portions of the top cap Cl and the vent unit C 2  may be insulated from the battery can  112 . 
     Meanwhile, the cap assembly  113  may further include a current interrupt device C 4 . The current interrupt device C 4  is also called CID. When the internal pressure of the battery increases due to gas generation so that the shape of the vent unit C 2  is reversed, the contact between the vent unit C 2  and the current interrupt device C 4  may be broken, or the current interrupt device C 4  may be damaged, thereby blocking the electrical connection between the vent unit C 2  and the electrode assembly  116 . 
     The above configuration of the battery cell  110  is widely known to those skilled in the art at the time of filing of this application, and thus will not be described in more detail. In addition, although an example of the cylindrical battery cell  110  is illustrated in  FIG.  3   , the battery module  100  according to the present disclosure is not limited to the configuration of the battery cell  110  having a specific shape. That is, various types of battery cells known at the time of filing of this application may be employed in the battery module  100  according to the present disclosure. 
     In addition, the connection plate  120  may have electrical conductivity to electrically connect the plurality of battery cells  110 . The connection plate  120  may include, for example, aluminum, nickel, or copper. The connection plate  120  may include a body portion  121  and a connection portion  122 . The body portion  121  may have a plate shape extending in a horizontal direction. The body portion  121  may be mounted to an upper portion or a lower portion of the module case  130 . The connection portion  122  may have a shape extending from the body portion  121  to contact the electrode terminal  111 . For example, as shown in  FIG.  2   , the connection portion  122  may have a bifurcated structure protrusively extending from the body portion  121 . The connection portion  122  may be welded to the electrode terminal  111 . At this time, as a welding method, resistance welding may be used, for example. 
     Moreover, the connection plate  120  may be mounted to an outer side of the module case  130 . For example, as shown in  FIG.  2   , the two connection plates  120  may be mounted to the upper portion and the lower portion of the module case  130 , respectively. 
     The module case  130  may be configured to accommodate the plurality of battery cells  110  therein. The module case  130  may include an upper frame  133  and a lower frame  134 . Each of the upper frame  133  and the lower frame  134  may include a plurality of hollows  135  configured so that the plurality of battery cells  110  are partially inserted therein. The module case  130  may have a plurality of exposure holes  131 . Each of the plurality of exposure holes  131  may be formed by perforating a part of the module case  130  so that the electrode terminals  111  of each of the plurality of battery cells  110  may be exposed to the outside. For example, as shown in  FIG.  2   , a plurality of exposure holes  131  may be provided in each of the upper surface of the upper frame  133  and the lower surface of the lower frame  134 . The space between the upper surface of the upper frame  133  and the connection plate  120  may serve as a venting space in front of the battery cell  110 . 
     The module case  130  includes a cover portion  132  having a shape protruding toward the connection plate  120 . When the battery cell  110  explodes due to abnormal behavior of the battery cell  110  so that an internal material is ejected to the outside, the cover portion  132  may be configured to prevent the internal material from moving to other adjacent battery cells  110  through other adjacent exposure holes  131 . The cover portion  132  may be formed to surround the exposure hole  131 . The cover portion  132  may have a rib shape protruding upward from the outer surface of the module case  130 . 
     Therefore, according to this configuration of the present disclosure, the module case  130  included in the battery module  100  according to the present disclosure includes the cover portion  132  protruding from the outer circumference of the exposure hole  131  toward the connection plate  120 . This structure may physically block the movement of a high-temperature active material discharged from the exploded battery cell to adjacent battery cells while maintaining the function of ejecting, namely venting, the gas and flame generated when the battery cell is ignited. By doing so, when the battery cell  110  behaves abnormally to explode so that the internal material is ejected, gas and flame are ejected through the exposure hole  131 , but the movement of the high-temperature active material is suppressed by the cover portion  132 . Therefore, it is possible to prevent the internal material from moving to other adjacent battery cells  110  through other exposure holes  131 . Therefore, it is possible to prevent chain ignition, such as propagating of thermal runaway, fire or explosion to other battery cells  110 . Accordingly, the present disclosure may greatly improve the safety. 
       FIG.  4    is a partial vertical sectional view schematically showing a part of the battery module of  FIG.  1   , cut in a front and rear direction. At this time, the configuration of the connection portion  122  of the connection plate  120  is not shown in  FIG.  4    for convenience of drawing description. 
     Referring to  FIG.  4    along with  FIG.  2   , the cover portion  132  of the battery module  100  of the present disclosure may be configured in a form where a hollow H is formed and at least a top end thereof is opened. The top end of the cover portion  132  may be configured to be in contact with the lower surface of the connection plate  120 , or may be positioned to be spaced apart from the lower surface of the connection plate  120  to secure a tolerance gap. 
     Therefore, according to this configuration of the present disclosure, since the top portion of the cover portion  132  is in contact with the lower surface of the connection plate  120 , even if an explosion occurs in some of the plurality of battery cells  110 , it is possible to prevent the high-temperature active material, gas and flame from moving to adjacent battery cells  110  through the empty space between the connection plate  120  and the module case  130 . The space between the upper surface of the upper frame  133  and the connection plate  120  serves as a venting space in front of the battery cell  110 , and the cover portion  132  maintains the venting space in an upward direction of the battery cell  110 , while making the venting space maintaining the venting space to be independent for each battery cell  110  in a lateral direction of the battery cell  110 . Accordingly, the cover portion  132  may suppress that the high-temperature active material is discharged to move to adjacent battery cells  110 , while maintaining the function of ejecting the gas and flame generated during ignition. The cover portion  132  constitutes an isolated mechanism structure for each battery cell  110  so as to suppress the scattering of an active material mass. In this way, chain ignition may be suppressed, thereby greatly improving the safety of the battery module  100  of the present disclosure. 
       FIG.  5    is a partial sectional view schematically showing a battery module according to another embodiment of the present disclosure. 
     Referring to  FIG.  5   , in the battery module  100  according to another embodiment of the present disclosure, the cover portion  132  may further include a bending part  132   a.  The bending part  132   a  may be configured to hide a part of the exposure hole  131  of the module case  130 . The bending part  132   a  may be a portion bent to extend in a horizontal direction from an end of the cover portion  132  protruding upward. The bending part  132   a  may be configured to hide a part of the open end of the cover portion  132 . For example, the bending part  132   a  may be configured to be bent toward the central from the open end of the upper portion of the cover portion  132  so that the opening of the open end is more narrowed. 
     Therefore, according to this configuration of the present disclosure, in the present disclosure, even if an explosion occurs in some of the plurality of battery cells  110  to eject an internal material (e.g., an active material), the amount of material discharged to the outside of the module case  130  may be effectively reduced by the bending part  132   a.  Accordingly, it is possible to effectively reduce the movement of the internal material ejected from the exploded battery cell  110  to other adjacent battery cells  110 . Ultimately, in the present disclosure, it is possible to provide the battery module  100  with greatly improved safety. 
       FIG.  6    is a partial sectional view schematically showing a part of a battery module according to still another embodiment of the present disclosure. 
     Referring to  FIG.  6    along with  FIG.  2   , the cover portion  132  of the battery module  100  according to another embodiment of the present disclosure may include an accommodation groove  132 b. The accommodation groove  132 b may be formed by indenting a part of the cover portion  132  so that the connection portion  122  of the connection plate  120  may pass therethrough or be accommodated therein. For example, referring to  FIG.  6   , the accommodation groove  132 b of the cover portion  132  may be formed by indenting a part of the upper end of the cover portion  132  downwards. 
     Therefore, according to this configuration of the present disclosure, by providing the accommodation groove  132 b to the cover portion  132 , the connection portion  122  of the connection plate  120  may be easily connected to the electrode terminal  111  of the battery cell  110 . 
       FIG.  7    is a partial sectional view schematically showing a part of a battery module according to still another embodiment of the present disclosure. 
     Referring to  FIG.  7    along with  FIGS.  2  and  6   , the connection plate  120  of the battery module  100  according to another embodiment of the present disclosure may include a plurality of connection holes  123 . The connection hole  123  may be formed by opening a part of the body portion  121 . The connection hole  123  may be configured so that the connection portion  122  is located inside the opening. That is, the connection portion  122  may have a shape extending from the outer circumference of the connection hole  123  formed in the body portion  121 . 
     In addition, the cover portion  132  may be configured such that an upwardly protruding part thereof is inserted into the connection hole  123 . In other words, the cover portion  132  may be configured such that the open end thereof is inserted into the connection hole  123 . The top end of the cover portion  132  may be positioned parallel to the upper surface of the body portion  121  of the connection plate  120 . 
     Therefore, according to this configuration of the present disclosure, in the present disclosure, the gap between the cover portion  132  and the connection plate  120  may be effectively reduced by inserting the open end of the cover portion  132  into the connection hole  123  of the connection plate  120 . Accordingly, in the present disclosure, even if an explosion occurs in some of the plurality of battery cells  110 , it is possible to effectively prevent a high-temperature active material, gas, flame, or the like from being moved through the empty space between the connection plate  120  and the module case  130 . Accordingly, the safety of the present disclosure may be greatly improved. 
       FIG.  8    is a partial sectional view schematically showing a part of a battery module according to still another embodiment of the present disclosure. 
     Referring to  FIG.  8   , the connection plate  120  of the battery module  100  according to still another embodiment of the present disclosure may further include an extension portion  124 , when compared with the connection plate  120  of  FIG.  4   . The extension portion  124  may be configured to screen an internal material ejected from the battery cell  110 . The extension portion  124  may be bent to extend from the connection hole  123  toward the battery cell  110 . 
     For example, as shown in  FIG.  8   , the extension portion  124  extending downward may be provided to each of the plurality of connection holes  123 . The extension portion  124  may be configured to be inserted into the cover portion  132 . The extension portion  124  may extend to face the inner surface of the inside of the cover portion  132 . The extension portion  124  may have a rib shape extending downward and having a ‘C’ shape on a plane to correspond to the internal structure of the cover portion  132 , for example. 
     Therefore, according to this configuration of the present disclosure, in the present disclosure, since the extension portion  124  of the connection plate  120  is provided, even if an explosion occurs in some of the plurality of battery cells  110 , it is possible to effectively prevent the internal material of the battery cell  110  or high-temperature active material, gas, flame, or the like from moving through the empty space between the connection plate  120  and the module case  130 . Accordingly, the safety of the present disclosure may be greatly improved. 
     Referring to  FIGS.  1 ,  2  and  4    again, the battery module  100  according to an embodiment of the present disclosure may further include a heat conduction pad  140 . The heat conduction pad  140  may have a material with high thermal conductivity while being electrically insulating. For example, the heat conduction pad  140  may include a silicone resin. 
     In addition, the heat conduction pad  140  may be mounted to an outer side of the connection plate  120 . The heat conduction pad  140  may include a plurality of communication holes  141 . The communication hole  141  may be formed to communicate with the connection hole  123  formed in the connection plate  120 . The heat conduction pad  140  may be configured to transfer heat transferred to the connection plate  120  to the outside with high thermal conductivity. In addition, the communication hole  141  may be formed to be relatively smaller than the opening size of the connection hole  123 . For example, as shown in  FIG.  2   , the heat conduction pad  140  may include a plurality of communication holes  141  configured to respectively communicate with the plurality of connection holes  123  formed in the connection plate  120 . Each of the plurality of communication holes  141  may have a size smaller than the opening size of each of the plurality of connection holes  123 . 
     Therefore, according to this configuration of the present disclosure, in the present disclosure, by forming the communication hole  141  relatively smaller than the opening size of the connection hole  123 , the communication hole  141  may effectively screen the high-temperature active material discharged to the outside through the connection hole  123  of the connection plate  120 , thereby greatly reducing the amount of the high-temperature active material discharged to the outside. Accordingly, the present disclosure may provide the battery module  100  with greatly improved safety. 
       FIG.  9    is a vertical sectional view schematically showing a part of the battery module according to still another embodiment of the present disclosure. 
     Referring to  FIG.  9    along with  FIG.  2   , the heat conduction pad  140  of the battery module  100  according to still another embodiment of the present disclosure may include two or more screen portions  142  provided inside or outside the communication hole  141 . Each of the two or more screen portions  142  may be configured to screen the internal material ejected from the battery cell  110 . The two or more screen portions  142  may have a shape extending from the outer circumference of the communication hole  141  toward the center of the communication hole  141 . The two or more screen portions  142  may be positioned to be spaced apart from each other in a vertical direction. 
     For example, as shown in  FIG.  9   , two screen portions  142  may be positioned at the inner upper end and inner lower end of the communication hole  141  of the heat conduction pad  140 , respectively. The two screen portions  142  have a shape protruding from the outside of the communication hole  141  toward the center of the communication hole  141 . 
     In addition, the heat conduction pad  140  may be configured such that, when an explosion occurs in some of the plurality of battery cells  110 , the generated gas passes through the screen portion  142 . In this case, the two or more screen portions  142  may be configured to screen fragments of the high-temperature electrode assembly, particularly high-temperature active material, ejected from the exploded battery cell  110  not to pass through the communication hole  141 . 
     Therefore, according to this configuration of the present disclosure, in the present disclosure, since two or more screen portions  142  are provided to the heat conduction pad  140 , it is possible to effectively prevent high-temperature fragments of the electrode assembly ejected from the exploded battery cell  110  from moving to other adjacent battery cells  110 . Accordingly, the present disclosure may provide the battery module  100  with high safety. 
     Meanwhile, a battery pack according to an embodiment of the present disclosure may include at least one battery module  100  as described above and a battery management system (BMS) electrically connected to the battery module  100 . The BMS may include various circuits or elements to control charging and discharging of the plurality of battery cells. 
     Meanwhile, a vehicle (not shown) according to an embodiment of the present disclosure may include at least one battery module  100  as described above and a vehicle body having an accommodation space for accommodating the battery module  100 . For example, the vehicle may be an electric vehicle, an electric scooter, an electric wheelchair, or an electric bike. 
     Meanwhile, even though the terms indicating directions such as upper, lower, left, right, front and rear directions are used in the specification, it is obvious to those skilled in the art that these merely represent relative locations for convenience in explanation and may vary based on a location of an observer or an object. 
     The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description.