Patent Publication Number: US-2020287180-A1

Title: Battery module and battery pack

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority to Chinese Patent Application No. 201910173449.0, filed on Mar. 7, 2019, the content of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to the technical field of energy storage devices, and in particular, relates to a battery module and a battery pack. 
     BACKGROUND 
     In recent years, with a continuous increasing of energy density of battery unit, it is urgent to improve the safety of the battery unit in the development of electric vehicles, and the thermal runaway is a focused issue in the research about safety of the battery unit. A battery pack, as the power resource of electric vehicles, is usually installed in the chassis of the electric vehicles. The battery pack includes a plurality of battery modules, and each battery module includes a plurality of battery units arranged in series and a plurality of bus bars electrically connected to the plurality of battery units. 
     In the related art, the battery module of the battery pack is provided with no fireproof component. When the thermal runaway occurs in the battery unit, a vent of the battery unit may eject flame and high-temperature particles, and the flame and high-temperature particles are likely to burn adjacent battery units, causing a chain reaction. In this way, a more serious safety accident may occur in the whole battery pack. 
     SUMMARY 
     In view of above, the present disclosure provides a battery module and a battery pack, aiming to solve the technical problems in the related art. 
     According to a first aspect of the present disclosure, a battery module is provided. The battery module includes: at least one battery unit array structure, each of the at least one battery unit array structure a plurality of battery units and a plurality of busbars electrically connected to the plurality of battery units; an upper cover; a lower cover, the at least one battery unit array structure being disposed between the upper cover and the lower cover; and a fireproof component disposed vertically. Each of the plurality of battery units in each of the at least one battery unit array structure is provided with a vent facing towards the fireproof component. 
     As a preferable structure of the present disclosure, the at least one battery unit array structure includes two or more battery unit array structures including a first battery unit array structure and a second battery unit array structure. The vent of each of the plurality of battery units of the first battery unit array structure and the vent of each of the plurality of battery units of the second battery unit array structure both face towards the fireproof component, and the fireproof component is disposed between the vent of each of the plurality of battery units of the first battery unit array structure and the vent of each of the plurality of battery units of the second battery unit array structure. 
     As a preferable structure of the present disclosure, the fireproof component includes a fireproof main body, and a first extension portion connected to an upper end of the fireproof main body and extending towards the first battery unit array structure. 
     As a preferable structure of the present disclosure, the fireproof component further includes a second extension portion connected to the upper end of the fireproof main body and extending towards the second battery unit array structure. 
     As a preferable structure of the present disclosure, the battery module further includes a fire-extinguishing component. The fire-extinguishing component is provided below the at least one battery unit array structure, and the fire-extinguishing component is provided with a fluid passageway for storing a fire-extinguishing liquid. 
     As a preferable structure of the present disclosure, the fireproof main body, the first extension portion and the second extension portion are formed into one piece. 
     As a preferable structure of the present disclosure, the fireproof component includes a fireproof main body, and a third extension portion connected to an upper end of the fireproof main body and extending towards the plurality of battery units; and/or the fireproof component includes the fireproof main body, and a fourth extension portion connected to a lower end of the fireproof main body and extending towards the plurality of battery units. 
     As a preferable structure of the present disclosure, one battery unit array structure of the at least one battery unit array structure further includes a collecting plate. The collecting plate is disposed at a side of the one battery unit array structure and connected to the plurality of battery units of the one battery unit array structure. 
     As a preferable structure of the present disclosure, the fireproof component has a melting point higher than or equal to 500 □. 
     As a preferable structure of the present disclosure, the fireproof component is made of a mica plate. 
     As a preferable structure of the present disclosure, the fireproof component is made of mica. 
     Different from the related art, in the above technical solutions, all the vents of the plurality of battery units of the battery unit array structures face towards the fireproof component. When thermal runaway occurs in a specific battery unit, flame and high-temperature particles ejected from a vent of the battery unit are blocked by the fireproof component from burning adjacent battery units, thereby preventing the thermal runaway in the other battery units from being triggered by the existing thermal runaway. 
     In order to solve the above technical problem, a second aspect of the present disclosure provides a battery pack is provided. The battery pack includes an accommodating box, and a plurality of battery modules accommodated in the accommodating box. One of the plurality of battery modules is the battery module according to the first aspect. 
     Different from the related art, in the above technical solutions, all the vents of the plurality of battery units of the battery unit array structures face towards the fireproof component. When thermal runaway occurs in a specific battery unit, flame and high-temperature particles ejected from a vent of the battery unit are blocked by the fireproof component from burning adjacent battery units, thereby preventing the thermal runaway in the other battery units from being triggered by the existing thermal runaway. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an exploded view of a battery pack according to a specific embodiment; 
         FIG. 2  is an exploded view of a battery module according to a specific embodiment; 
         FIG. 3  is a cross-sectional view of a battery module according to a specific embodiment; 
         FIG. 4  is an exploded view of a battery unit array structure according to a specific embodiment; 
         FIG. 5  is a schematic structural diagram of a battery unit array structure according to a specific embodiment; 
         FIG. 6  is a schematic structural diagram of a fireproof component according to a specific embodiment; 
         FIG. 7  is a schematic structural diagram of a fireproof component according to another specific embodiment; 
         FIG. 8  is an exploded view of a battery unit according to a specific embodiment; 
         FIG. 9  is a cross-sectional view of a battery assembly in form of a wound structure according to a specific embodiment; and 
         FIG. 10  is a cross-sectional view of a battery assembly in form of a layered structure according to a specific embodiment. 
     
    
    
     REFERENCE SINGS 
     
         
         
           
               1 . battery module
             10  battery unit array structure
                 101  first battery unit array structure     102  second battery unit array structure   
                 11  battery unit
                 111  battery assembly
                     1111  first electrode plate     1112  second electrode plate     1113  separator     1114  flat surface   
                     112  battery casing
                     1121  first surface     1122  second surface   
                     113  electrode terminal connector     114  cover plate     115  electrode terminal     116  vent   
                 12  busbar     13  upper cover     14  lower cover     15  collecting plate     16  end plate     17  fireproof component
                 171  fireproof main body     172  first extension portion     173  second extension portion     174  third extension portion     175  fourth extension portion   
                 18  fire-extinguishing component     
               2  box cover 
               3  box body
             31  fixing beam     4  pressing bar     5  high-temperature particles.   
         
           
         
       
    
     DESCRIPTION OF EMBODIMENTS 
     The technical solutions will be described in detail below with reference to specific embodiments and accompanying drawings in term of technical content, structural features, and objects and effects. 
     The terms “first”, or “second” in the description are used for a purpose of description only, but not intended to indicate or imply relative importance thereof. Unless otherwise specified or stated, term “a plurality of” means two or more, terms “connected”, “fixed”, etc. shall be understood in a broad sense. For example, the term “connected” includes various connection manners, such as fixed connection, detachable connection, integrated connection, electrical connection, direct connection or indirect connection via an intermediate medium. These skilled in the art are able to understand specific meanings of the above terms in accordance with specific circumstances. 
     It should be understood that terms indicating orientations or positions, such as “upper”, “lower”, “left”, “right”, etc., generally are used to describe the orientations or positions with reference to the drawings, and thus should not be construed as a limitation of the present disclosure. It also should be understood that when an element is referred as being “on” or “under” another element, the element can be directly located “on” or “under” another element or connected to another element with an intermediate element. 
       FIG. 1  illustrates a battery pack according to an embodiment. The battery pack includes an accommodating box and a plurality of battery modules  1  disposed in the accommodating box. The plurality of battery modules  1  can be arranged either along a horizontal direction (a length direction indicated by arrow x or a width direction indicated by arrow y), or along a vertical direction (a direction indicated by arrow z). 
     In an example, the accommodating box includes a box cover  2  and a box body  3 . A plurality of fixing beams  31  is provided on the box body  3 . In another embodiment, the fixing beams  31  can also be provided on the box cover  2 . In the present embodiment, the fixing beams  31  can be protruding beams that protrude upwards from the bottom of the box body  3 , or act as separate components that are welded on the bottom of the box body  3 . 
     The battery pack further includes pressing bars  4 . The pressing bars  4  press both ends of the battery module  1  against the fixing beams  31 , so as to fix the battery module  1  to the box body  3 . In this case, the battery module  1  is fixed by the pressing bars  4 . 
     In an embodiment as shown in  FIG. 2 , the battery module  1  includes an upper cover  13 , a lower cover  14 , a fireproof component  17 , a fire-extinguishing component  18 , and two battery unit array structures  10  (or more than two battery unit array structures  10 ). One of the two battery unit array structures  10  is a first battery unit array structure  101 , and the other one is a second battery unit array structure  102 . Both the first battery unit array structure  101  and the second battery unit array structure  102  are disposed between the upper cover  13  and the lower cover  14 . 
     In the present embodiment, each of the first battery unit array structure  101  and the second battery unit array structure  102  includes fourteen battery units  11  arranged along the length direction (indicated by arrow x). A number, length, height, volume and the like of the battery units  11  can be adjusted as needed. 
     In another embodiment, the battery module  1  includes only one battery unit array structure  10 , and each battery unit  11  in the battery unit array structure  10  is provided with a vent  116  facing towards the fireproof component  17 . 
     The fireproof component  17  is disposed vertically. The vents  116  of the first battery unit array structure  101  and the vents  116  of the second battery unit array structure  102  all face towards the fireproof component  17 , and the fireproof component  17  is disposed between the vents  116  of the first battery unit array structure  101  and the vents  116  of the second battery unit array structure  102 . 
     In this case, as the fireproof component  17  is disposed between the vents  116  of the first battery unit array structure  101  and the vents  116  of the second battery unit array structure  102 , the fireproof component  17  separates the battery units  11  of the first battery unit array structure  101  from the battery units  11  of the second battery unit array structure  102 , thereby preventing the existing thermal runaway in some battery units from triggering the thermal runaway in adjacent battery units. 
     In an example, the fire-extinguishing component  18  is provided below the battery unit array structure  10 , and the fire-extinguishing component  18  is provided with a fluid passageway for storing a fire-extinguishing liquid. The fire-extinguishing component  18  extends along a direction in which the battery units  11  are arranged, and has a length in the length direction (indicated by arrow x) that is substantially same as or different from that of the battery unit array structure  10 . 
     In this embodiment, the fire-extinguishing component  18  is disposed below the lower cover  14 , and the fire-extinguishing liquid can be provided inside the fire-extinguishing component  18 . In this way, on the one hand, during a normal operating process of the battery module  1 , the fire-extinguishing liquid serves as a cooling liquid used for cooling the battery units  11  of the battery unit array structure  10 ; and on the other hand, when the thermal runaway occurs and the battery unit  11  is on fire, the fire-extinguishing component  18  melts and releases the fire-extinguishing liquid to extinguish the flame, thereby reducing the damage caused by the thermal runaway of the battery unit  11 . 
     As shown in  FIG. 3 , when the thermal runaway occurs in the battery unit  11  (the battery unit  11  of the first battery unit array structure  101  or the battery unit  11  of the second battery unit array structure  102 ), the vent  116  is broken to eject flame and high-temperature particles  5 . At this time, the flame and the high-temperature particles  5  are ejected from the battery unit  11  in a horizontal direction (either the length direction indicated by arrow x or the width direction indicated by arrow y), and blocked by the fireproof component  17 . Thus, the high-temperature particles  5  fall, and burn through the lower cover  14  as well as the fire-extinguishing component  18 , such that the fire-extinguishing liquid in the fire-extinguishing component  18  cool the high-temperature particles  5 . In this way, the damage to the battery units  11  caused by the thermal runaway can be reduced. 
     In an embodiment shown in  FIG. 4  and  FIG. 5 , the battery unit array structure  10  includes a plurality of battery units  11  and a plurality of busbars  12  electrically connected to the plurality of battery units  11 . The plurality of battery units  11  is arranged in the horizontal direction (the length direction indicated by arrow x or the width direction indicated by arrow y). A collecting plate  15  is vertically disposed at a side of the battery unit array structure  10 , and the collecting plate  15  is connected to the e battery units  11  in the battery unit array structure  10 . 
     In the present embodiment, the battery unit array structure  10  further includes two end plates  16 , and the two end plates  16  are respectively located at two ends of the plurality of battery units  11  in the horizontal direction (the length direction indicated by arrow x or the width direction indicated by arrow y). 
     In a specific embodiment, a side surface of the battery unit  11  is applied with glue and is bonded to an adjacent battery unit  11 . The plurality of battery units  11  is provided with the end plates  16  at the two ends, so as to form the battery unit array structure  10 . The battery units  11  are electrically connected to one another via the busbars  12 . The collecting plate  15  is provided at the positions of busbars  12  of the battery unit array structure  10 . The battery unit array structure  10  lies on the lower cover  14 , a lower surface of the battery unit array structure  10  is fixed to the lower cover  14  through a structural adhesive, and an upper surface of the battery unit array structure  10  is fixed to the upper cover  13  through a structural adhesive. 
     In an embodiment shown in  FIG. 6 , the fireproof component  17  includes a fireproof main body  171 , and a first extension portion  172  connected to an upper end of the fireproof main body  171  and extending towards the first battery unit array structure  101 . 
     The fireproof component  17  further includes a second extension portion  173  connected to the upper end of the fireproof main body  171  and extending towards the second battery unit array structure  102 . In the present embodiment, the first extension portion  172  extends in the direction facing towards the first battery unit array structure  101 , and the second extension portion  173  extends in the direction facing towards the second battery unit array structure  102 . However, the extension of the first extension portion  172  and the second extension portion  173  are not limited to the extension in the horizontal direction (the length direction indicated by arrow x or the width direction indicated by arrow y) as shown in  FIG. 6 . It is possible that the first extension portion  172  and the second extension portion  173  extend obliquely upward and downward, or extend along an arc or the like. 
     In the present embodiment, for example, the fireproof component  17  is T-shaped. Through the cooperation between the T-shaped fireproof component  17  and the fire-extinguishing component  18 , not only the flame and the high-temperature particles  5  can be prevented from being ejected upwards in a vertical direction (a direction indicated by arrow z) and endangering the passenger compartment, but also the flame and high-temperature particles  5  can be ejected downwards to cause melting of the fire-extinguishing component  18 , further reducing the damage to the battery units  11  caused by the thermal runaway. 
     In an example, the fireproof main body  171 , the first extension portion  172  and the second extension portion  173  are formed into one piece. In this way, the processing of the fireproof component  17  can be simplified. 
     In another embodiment shown in  FIG. 7 , the fireproof component  17  includes a fireproof main body  171  and a third extension portion  174  connected to an upper end of the fireproof main body  171 , and the third extension portion  174  extends towards the battery unit  11 ; and/or the fireproof component  17  includes a fireproof main body  171  and a fourth extension portion  175  connected to a lower end of the fireproof main body  17 , and the fourth extension portion  175  extends towards the battery unit  11 . 
     In another embodiment shown in  FIG. 7 , the fireproof component  17  includes a fireproof main body  171 , a third extension portion  174 , and a fourth extension portion  175 . The positions and shapes of the third extension portion  174  and the fourth extension portion  175  are not specifically limited, as long as the third extension portion  174  is configured to prevent the flame and high-temperature particles  5  from being ejected upwards in the vertical direction (the direction indicated by arrow z) and the fourth extension portion  175  is configured to prevent the flame and high-temperature particles  5  from being ejected downwards in the vertical direction (the direction indicated by arrow z), i.e., both acting as protections. Other embodiment, in which the flame and high-temperature particles  5  can be blocked from burning and damaging the adjacent battery units, shall fall within the protection scope of the present disclosure. 
     It should be noted that the above-mentioned fireproof component  17  can include any combination of the first extension portion  172 , the second extension portion  173 , the third extension portion  174 , and the fourth extension portion  175 . In practical applications, the shape of the fireproof component  17  can be adjusted according to the actual situation, in order to achieve the optimal effect. The shape of the fireproof component  17  is not limited to the shape shown in the present embodiment. 
     The fireproof component  17  has a melting point higher than or equal to 500 □, such that the flame cannot melt the fireproof component  17 , thereby achieving the fireproofness. With respect to the fireproof component  17  made of a mica plate in a specific embodiment, the mica plate has an extremely high melting point (about 1723 □), which meets the requirement on the fireproofness of the fireproof component  17 , and the mica plate also has excellent processing properties. The fireproof component  17  is not limited to the embodiment of mica plate. 
     As shown in  FIG. 8 , the battery unit  11  includes an electrode assembly  111 , a battery casing  112 , electrode terminal connectors  113 , a cover plate  114 , and electrode terminals  115 . The battery casing  112  can have a hexahedral shape or any other shape. The battery casing  112  has an inner space for accommodating the electrode assembly  111  and the electrolyte, and an opening. The electrode assembly  111  is accommodated in the battery casing  112 , the cover plate  114  covers the opening and configured to enclose the electrode assembly  111  in the battery casing  112 , and the electrode assembly  111  is electrically connected to the electrode terminals  115  through the electrode terminal connectors  113 . In the present embodiment, there are two electrode terminal connectors  113 , i.e., a positive terminal connector  113  and a negative terminal connector  113 . The battery casing  112  can be made of a material such as aluminum, aluminum alloy, or plastic. 
     The electrode assembly  111  is accommodated in the battery casing  112  and include a first electrode plate  1111 , a second electrode plate  1112 , and a separator  1113  disposed between the first electrode plate  1111  and the second electrode plate  1112 . The first electrode plate  1111  is a positive electrode plate or a negative electrode plate, and the second electrode plate  1112  has opposite polarity to the first electrode plate  1111 , i.e., the second electrode plate  1112  is a negative electrode plate or a positive electrode plate. The separator  1113  is an insulator interposed between the first electrode plate  1111  and the second electrode plate  1112 . The electrode assembly  111  can be in form of a wound structure (as shown in  FIG. 9 ) or a layered structure ( FIG. 10 ). 
     For purpose of illustration, the first electrode plate  1111  is a positive electrode plate and the second electrode plate  1112  is a negative electrode plate. In other embodiments, it is possible that the first electrode plate  1111  is a negative electrode plate and the second electrode plate  1112  is a positive electrode plate. In addition, a positive electrode active material is coated on a coating region of the positive electrode plate, and a negative electrode active material is coated on a coating region of the negative electrode plate. An uncoated region extending from each coating region acts as a tab. The electrode assembly  111  includes two tabs, i.e., a positive tab and a negative tab. The positive tab extends from the coating region of the positive electrode plate, and the negative tab extends from the coating region of the negative electrode plate. The positive electrode tab is electrically connected to the positive electrode terminal  115  through the positive electrode terminal connector  113 , and the negative electrode tab is electrically connected to the negative electrode terminal  115  through the negative electrode terminal connector  113 . 
     The battery casing  112 , in an approximately hexahedral form, includes two first surfaces  1121  and two second surfaces  1122 . Each of the first surfaces  1121  has a larger area than each of the second surfaces  1122 . In the battery module  1 , the two second surfaces  1122  of each battery unit  11  are opposite to each other in the horizontal direction (for example, the length direction indicated by arrow x), and the two first surfaces  1121  of each battery unit  11  are opposite to each other in the vertical direction (the direction indicated by arrow z). 
     When the electrode assembly  111  is in form of a wound structure, as shown in  FIG. 9 , the electrode assembly  111  is flat, and the outer surfaces of the electrode assembly  111  include two flat surfaces  1114 . The two flat surfaces  1114  are opposite to one another in the vertical direction (the direction indicated by arrow z). In other words, the flat surfaces  1114  are opposite to the first surfaces  1121 . The electrode assembly  111  has an approximately hexahedral form, and the flat surface  1114  is substantially parallel to a winding axis and is an outer surface having the largest area. The flat surface  1114  can be a relatively flat surface, rather than a strictly flat surface. 
     When the electrode assembly  111  is in form of a layered structure, as shown in  FIG. 10 , the first electrode plate  1111 , the separator  1113 , and the second electrode plate  1112  are stacked in the vertical direction (the direction indicated by arrow z), i.e., the first electrode plate  1111  is opposite to the first surface  1121 . 
     During a charging and discharging process, the electrode assembly  111  inevitably expands in a thickness direction of the first electrode plate  1111 . In the electrode assembly  111  of the wound structure, an expansion force is greatest in a direction perpendicular to the flat surface  1114 . In the electrode assembly  111  of the layered structure, the expansion force is greatest in a stacking direction of the first electrode plate  1111  and the second electrode plate  1112 . 
     The electrode assembly  111  can adopt the wound structure or the layered structure. When the electrode assembly  111  is in form of the wound structure, the flat surfaces  1114  are located in the vertical direction (the direction indicated by arrow z). When the electrode assembly  111  is in form of the layered structure, the first electrode plate  1111  and the second electrode plate  1112  are stacked in the vertical direction (the direction indicated by arrow z). It can be seen that, whether the electrode assembly  111  adopts the wound structure or the layered structure, the maximum expansion force applied by the electrode assembly  111  on the battery casing  112  is oriented in the vertical direction. 
     On the contrary, in the battery unit  11  of the battery module  1  in the related art, the maximum expansion force applied by the electrode assembly  111  on the battery casing  112  is always oriented in the horizontal direction. The battery module  1  has a much greater size in the horizontal direction than that in the vertical direction. For example, due to the limitation on the height of a vehicle chassis, more battery units  11  have to be stacked in the horizontal direction, the expansion force is accumulated in the horizontal direction. In this regard, the battery module  1  is subjected to an extremely great expansion force in the horizontal direction, and it is necessary to provide very thick end plates on both sides of the battery module  1  in the horizontal direction to resist the expansion force. However, the increased thickness of the end plates can lower the energy density of the battery module  1 . In the present embodiment, as the maximum expansion force applied by the electrode assembly  111  on the battery casing  112  is oriented in the vertical direction and the number of battery units  11  stacked in the vertical direction is smaller, the maximum expansion force of the battery module  1  is substantially reduced when compared with the related art. 
     The battery unit  11  can produce gas in the battery casing  112  during the charging and discharging process, the produced gas exerts a force on the battery casing  112 , thereby intensifying the expansion of the battery casing  112 . In the present disclosure, as the first surface  1121  has a larger area than the second surface  1122  and the two first surfaces  1121  of the battery unit  11  are opposite to each other in the vertical direction, the maximum force applied by the produced gas on the battery casing  112  is also oriented in the vertical direction. Compared with the related art, the maximum expansion force of the battery module  1  is further reduced. 
     It should be understood that the embodiments according to the present disclosure discussed above are merely illustrative embodiments, but not intended to limit the present disclosure. The technical solution according to the present disclosure can be modified or changed in various manners. Based on the description or the accompanying drawing, any modifications, equivalent replacements, improvements, and direct or indirect applications in other related arts should fall within the scope of protection of the present disclosure.