Patent Publication Number: US-2022238937-A1

Title: Battery module and battery pack including the same

Description:
CROSS CITATION WITH RELATED APPLICATION(S) 
     This application claims the benefit of Korean Patent Application No. 10-2019-0133808 filed on Oct. 25, 2019 with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a battery module and a battery pack including the same, and more particularly to a battery module having improved welding safety, and a battery pack including the same. 
     BACKGROUND ART 
     Secondary batteries, which are easily applicable to various product groups and have electrical characteristics such as high energy density, are universally applied not only for a portable device but also for an electric vehicle or a hybrid electric vehicle, an energy storage system or the like, which is driven by an electric driving source. Such secondary battery is attracting attention as a new environment-friendly energy source for improving energy efficiency since it gives a primary advantage of remarkably reducing the use of fossil fuels and also does not generate by-products from the use of energy at all. 
     Currently commercialized secondary batteries include a nickel cadmium battery, a nickel hydrogen battery, a nickel zinc battery, and a lithium secondary battery. Among them, the lithium secondary battery has come into the spotlight because they have advantages, for example, hardly exhibiting memory effects compared to nickel-based secondary batteries and thus being freely charged and discharged, and having very low self-discharge rate and high energy density. 
     Such lithium secondary battery mainly uses a lithium-based oxide and a carbonaceous material as a positive electrode active material and a negative electrode active material, respectively. 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 between them, and an exterior material, i.e., battery case, which seals and houses the electrode assembly together with an electrolyte solution. 
     Generally, the lithium secondary battery may be classified based on the shape of the exterior material into a prismatic type secondary battery in which the electrode assembly is embedded in a metal can, and a pouch-type secondary battery in which the electrode assembly is embedded in a pouch of an aluminum laminate sheet. 
     Small-sized mobile devices use one to three battery cells for each device, whereas middle- or large-sized devices such as vehicles require high power and large capacity. Therefore, a middle- or large-sized battery module having a plurality of battery cells electrically connected to one another is used. 
     The middle- or large-sized battery module is preferably manufactured so as to have as small a size and weight as possible. Consequently, a prismatic type battery or a pouch-type battery, which can be stacked with high integration and has a small weight relative to capacity, is mainly used as a battery cell of the middle- or large-sized battery module. 
     Meanwhile, in order to protect a plurality of battery cells from external shock, heat, or vibration, the battery module may include a module frame member which houses the battery cell stack composed of a plurality of battery cells in an internal space. 
       FIG. 1  is a perspective view illustrating a conventional battery module  10 . 
     Referring to  FIG. 1 , the conventional battery module  10  includes a module frame  20  that houses the battery cell stack therein, and an end plate  30  that covers an opened front surface (Y-axis direction) and the other surface (direction opposite to the Y-axis) of the module frame  20 . 
       FIG. 2  is a cross-sectional view showing a part of a cross-section taken along the cutting line A of  FIG. 1 . 
     Referring to  FIG. 2 , in order to bond the module frame  20  and the end plate  30 , welding is performed on the joining surface in a state where the module frame  20  and the end plate  30  are located to face each other. 
     At this time, a laser welding may be performed for welding, and internal components including battery cells may be damaged due to the laser itself or weld spatters penetrated during the welding process. 
     Therefore, there is a need for a technology capable of solving the problems of the prior arts. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     Embodiments of the present disclosure have been designed to solve the above-mentioned problems involved in the prior art methods and, therefore, it is an object of the present disclosure to provide a battery module that can protect internal components during welding, and a battery pack including the same. 
     However, the problem to be solved by embodiments of the present disclosure is not limited to the above-described problems, and can be variously expanded within the scope of the technical idea included in the present disclosure. 
     Technical Solution 
     A battery module according to an embodiment of the present disclosure includes: a battery cell stack in which a plurality of battery cells are stacked; a module frame that houses the battery cell stack and has an opened front surface and an opened rear surface facing each other; an end plate that covers each of the front surface and the rear surface of the module frame; and an insulator interposed between the battery cell stack and the end plate, wherein the module frame includes a first joining surface formed on sides constituting each of the front surface and the rear surface, wherein the end plate includes a second joining surface joined to the first joining surface, and wherein the insulator includes a rib extending in a direction in which the battery cell stack is located. 
     The rib may be extended along a direction parallel to one of sides constituting each of the front surface and the rear surface of the module frame. 
     The rib may be extended from at least one of an upper side, a lower side, and both sides of the insulator. 
     The rib may be located between the first joining surface and the battery cell stack. 
     The rib may be integrated with the insulator. 
     The insulator may include at least one of polycarbonate, polypropylene, and polyethylene terephthalate. 
     The first joining surface and the second joining surface are weld-connected to each other. 
     The rib may include a first extension part separated from the first joining surface and extending in a direction in which the battery cell stack is located, and a second extension part extending from one end of the first extension part toward an inner side surface of the module frame. 
     The first extension part may be parallel to the inner side surface of the module frame, and the second extension part may be perpendicular to the inner side surface of the module frame. 
     The end plate may include a protruding part located on the center side of the end plate than the second joining surface and protruding in the direction in which the battery cell stack is located. 
     The rib may include a first extension part separated from the first joining surface and extending in a direction in which the battery cell stack is located, and a second extension part extending from one end of the first extension part toward the inner side surface of the module frame, and the protruding part comes into contact with the first extension part and the second extension part. 
     The protruding part may include a lower surface in contact with the first extension part, a side surface in contact with the second extension part, and an upper surface in contact with the inner side surface of the module frame. 
     A chamfer may be formed on the protruding part to improve the assembling property of the end plate and the module frame. 
     The module frame may be a mono frame in which an upper surface, a lower surface, and both sides are integrated. 
     The module frame may include a U-shaped frame having an opened front surface, an opened rear surface and an opened upper surface, and an upper cover covering the opened upper surface of the U-shaped frame. 
     Advantageous Effects 
     According to the embodiments of the present disclosure, it is possible to prevent the laser or weld spatter penetrated through the rib formed in the insulator from damaging the internal components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a conventional battery module. 
         FIG. 2  is a cross-sectional view showing a part of a cross section cut along the cutting line A of  FIG. 1 . 
         FIG. 3  is a perspective view of the battery module according to one embodiment of the present disclosure. 
         FIG. 4  is an exploded perspective view of the battery module of  FIG. 3 . 
         FIG. 5  is a cross-sectional view showing a part of a cross section cut along the cutting line B of  FIG. 3 . 
         FIG. 6  is a perspective view showing only the module frame and the insulator in the cross section cut along the cutting line B of  FIG. 3 . 
         FIG. 7  is a perspective view showing an end plate having a protruding part. 
         FIG. 8  is a cross-sectional view showing a state in which an end plate having a protruding part is connected to a module frame. 
         FIG. 9  is a perspective view showing a mono frame. 
         FIG. 10  is a perspective view showing a U-shaped frame and an upper cover. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement them. The present disclosure may be modified in various different ways, and is not limited to the embodiments set forth herein. 
     Portions that are irrelevant to the description will be omitted to clearly describe the present disclosure, and like reference numerals designate like elements throughout the specification. 
     Further, in the figures, the size and thickness of each element are arbitrarily illustrated for convenience of description, and the present disclosure is not necessarily limited to those illustrated in the figures. In the figures, the thickness of layers, regions, etc. are exaggerated for clarity. In the figures, for convenience of description, the thicknesses of some layers and regions are shown to be exaggerated. 
     In addition, it will be understood that when an element such as a layer, film, region, or plate is referred to as being “on” or “above” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, it means that other intervening elements are not present. Further, the word “on” or “above” means disposed on or below a reference portion, and does not necessarily mean being disposed on the upper end of the reference portion toward the opposite direction of gravity. 
     Further, throughout the specification, when a portion is referred to as “including” a certain component, it means that it can further include other components, without excluding the other components, unless otherwise stated. 
     Further, throughout the specification, when referred to as “planar”, it means when a target portion is viewed from the upper side, and when referred to as “cross-sectional”, it means when a target portion is viewed from the side of a cross section cut vertically. 
       FIG. 3  is a perspective view of the battery module  100  according to one embodiment of the present disclosure, and  FIG. 4  is an exploded perspective view of the battery module  100  of  FIG. 3 . 
     Referring to  FIGS. 3 and 4 , the battery module  100  according to one embodiment of the present disclosure includes: a battery cell stack, a module frame  200  that houses the battery cell stack and has an opened front surface (Y-axis direction) and an opened rear surface (direction opposite to the Y-axis) facing each other, an end plate  300  that covers each of the front surface and the rear surface of the module frame  200 ; and an insulator  400  interposed between the battery cell stack and the end plate  300 . 
     Although not specifically shown in  FIG. 4 , the battery cell stack is a structure in which a plurality of battery cells are stacked and is housed in the module frame  200 . 
     The module frame  200  is a structure in which the front surface and the rear surface facing each other are opened, and can protect the battery cell stack from the outside. 
     The end plate  300  can cover the front surface and the rear surface of the module frame  200  to protect electrode leads or bus bars. At this time, in order to prevent the end plate  300  from coming into contact with the electrode lead or the bus bar to cause a danger of short circuit or the like, the end plate  300  may be a metal plate having a predetermined strength, and an insulator  400  is interposed between the battery cell stack and the end plate  300 . 
       FIG. 5  is a cross-sectional view showing a part of a cross section cut along the cutting line B of  FIG. 3 . 
     Referring to  FIG. 5  together with  FIG. 4 , welding is performed in a state in which the first joining surface  250  of the module frame  200  and the second joining surface  350  of the end plate  300  come into contact with each other, so that the end plate  300  is joined to the module frame  200 . 
     The first joining surface  250  is located on the sides  210 ,  220 ,  230 , and  240  constituting the front surface (Y-axis direction) and the rear surface (direction opposite to the Y-axis) of the module frame  200 , respectively. The second joining surface  350  is also provided on the sides of the end plate  300  so as to correspond to the first joining surface  250 , and the first joining surface  250  and the second joining surface  350  are joined through welding. That is, the first joining surface  250  and the second joining surface  350  are weld-connected to each other. 
     The welding method is not limited, but it is preferable to perform laser welding. 
     However, if a laser beam is shot for welding, the laser beam may transmit through the module frame  200  and the end plate  300  to damage the battery cell stack or other internal components. Further, during the welding process, a weld spatter phenomenon in which welding sparks are scattered in all directions occurs, and the weld spatter can also damage the battery cell stack or other internal components. 
     Therefore, the insulator  400  in the present embodiment includes a rib  410  extending in a direction in which the battery cell stack is located. 
     The rib  410  may be extended from at least one of an upper side, a lower side, and both sides of the insulator  400 , and may be in a shape extending along a direction parallel to one of the sides  210 ,  220 ,  230 , and  240  constituting each of the front surface (Y-axis direction) and the rear surface (direction opposite to the Y-axis) of the module frame  200 .  FIGS. 4 and 5  show, for example, a state in which a rib  410  extending from the upper side of the insulator  400  extends along the direction parallel to the upper side  210  in the front surface (Y-axis direction) of the module frame  200 . 
     Through the structure of the rib  410  as described above, it is possible to block the transmitted laser beam or weld spatter from affecting the battery cell stack or other internal components. 
     In particular, as shown in  FIG. 5 , the rib  410  must be located between the first joining surface  250  and the battery cell stack, so the weld spatter can be effectively blocked. That is, the rib  410  may be located between the first joining surface  250  and the second joining surface  350  that are weld-connected to each other, and the battery cell stack. 
       FIG. 6  is a perspective view showing only the module frame and the insulator in the cross section cut along the cutting line B of  FIG. 3 . 
     Referring to  FIG. 6 , the rib  410  of the insulator  400  may include a first extension part  411  separated from the first joining surface  250  and extending in the direction in which the battery cell stack is located, and a second extension part  412  extending from one end of the first extension part  411  toward the inner side of the module frame  200 . In this case, the first extension part  411  may be parallel to the inner side surface of the module frame  200 , and the second extension part  412  may be perpendicular to the inner side surface of the module frame  200 . 
     The rib  410  may include a first extension part  411  and a second extension part  412  to form a kind of basket-like appearance. The rib  410  is disposed so as to surround the welded portion of the first joining surface  250  and the second joining surface  350 , and thus, can more effectively block the weld spatter in which welding sparks are scattered in all directions. 
     Further, the configuration of the rib  410  may be a structure that is easy to surround the protruding part of the end plate shown in  FIG. 7  described below. 
     Hereinafter, in  FIGS. 7 and 8 , as another embodiment of the present disclosure, an end plate  300   a  having a protruding part  360  and a configuration in which the protruding part  360  is surrounded by the rib  410  will be described. 
       FIG. 7  is a perspective view showing an end plate  300   a  having a protruding part  360 . Referring to  FIG. 7 , the second joining surface  350  is located on four sides  310 ,  320 ,  330 , and  340  of the end plate  300   a  corresponding to the four sides  210 ,  220 ,  230  and  240  of the module frame  200  shown in  FIG. 3 , respectively. 
     In this case, the end plate  300   a  may include a protruding part  360  located at the center side of the end plate  300   a  than the second joining surface  350  and protruding in a direction in which the battery cell stack is located. 
     The protruding part  360  may be formed on at least one of the four sides  310 ,  320 ,  330 , and  340  of the end plate  300   a,  and may be formed on all of the four sides  310 ,  320 ,  330  and  340  as shown in  FIG. 7 . 
     This protruding part  360  has a shape extending along a direction parallel to one of the four sides  310 ,  320 ,  330  and  340  of the end plate  300   a,  and can block the laser beam and weld sputter transmitted for welding from affecting the battery cell stack and other internal components. 
     Further, when the end plate  300   a  is connected to the module frame  200 , the protruding part  360  is inserted into the inner side space of the module frame  200 , so that the end plate  300   a  can be connected to a correct position without dislocation. That is, the protruding part  360  may play a role of improving the temporary assembling property between the module frame  200  and the end plate  300   a.    
     Meanwhile, the protruding part  360  may have a structure integrated with the end plate  300   a,  and the end plate  300   a  having the protruding part  360  may be manufactured by processing and molding. Since the previously set rib-shaped plates are not joined, a separate joining step is not required. 
     The protruding part  360  may be disposed in a space where the basket-shaped rib  410  is formed, which will be described in detail in  FIG. 8  below. 
       FIG. 8  is a cross-sectional view showing a state in which an end plate  300   a  having a protruding part  360  is connected to a module frame  200 . 
     Referring to  FIG. 8  together with  FIGS. 6 and 7 , the protruding part  360  of the end plate  300   a  can be disposed in a space where the rib  410  including the first extension part  411  and the second extension part  412  is formed. 
     Therefore, the protruding part  360  may include a lower surface in contact with the first extension part  411 , a side surface in contact with the second extension part  412 , and an upper surface in contact with the inner side surface of the module frame  200 . 
     Since the battery module in the present embodiment includes both the rib  410  and the protruding part  360 , it is possible to more effectively block the laser and weld spatter that can be transmitted during the welding process of the first joining surface  250  and the second joining surface  350 . 
     Specifically, the protruding part  360  may primarily block the laser that is transmitted from the first joining surface  250  and the second joining surface  350 , and the rib  410  of the insulator  400  may secondarily block the weld spatter that may be scattered into the gap between the protruding part  360  and the inner side surface of the module frame  200 . 
     Meanwhile, in  FIG. 7 , a chamfer  361  may be formed on the protruding part  360  to improve the assembling property of the end plate  300   a  and the module frame  200 . In particular, the chamfer  361  may be formed at a corner of the protruding part  360  that comes into contact with the inner side surface of the module frame  200 . 
     The protruding part  360  may be located adjacent to the first joining surface  250  and the second joining surface  350 , and thus, it may be difficult to insert the protruding part  360  into the inner side space of the module frame  200 . Through the chamfer  361 , it is possible to prevent this problem and improve the assembling property of the end plate  300  and the module frame  200 . 
     Meanwhile, the rib  410  may have a structure integrated with the insulator  400  and may be manufactured by plastic injection molding. Accordingly, the thickness or shape of the rib  410  can be freely modified according to the applied battery module. 
     Further, the insulator  400  is for preventing the end plate  300  from coming into contact with the electrode lead or the bus bar and causing a danger of short circuit or the like, and it is preferable to include a material exhibiting electrical insulation. 
     The material exhibiting such electrical insulation may include at least one of polycarbonate (PC), polypropylene (PP), and polyethylene terephthalate (PET) 
     Meanwhile, the module frame  200  in the present disclosure may be a mono frame or a U-shaped frame.  FIGS. 9 and 10  are for illustrating this.  FIG. 9  is a perspective view showing a mono frame  2001 , and  FIG. 10  is a perspective view showing a U-shaped frame  200   b  and an upper cover  210   b.  Other configurations are omitted for convenience of description. 
     First, referring to  FIG. 9 , the module frame used in the present disclosure may be a mono frame  200   a.    
     The mono frame  200   a  may have a structure of metal plate in which the front surface (Y-axis direction) and the rear surface (direction opposite to the Y-axis) are opened, and the upper surface (Z-axis direction), the lower surface (direction opposite to the Z-axis) and both side surfaces (X-axis direction and the opposite direction thereof) are integrated. The opened front surface and the opened rear surface of the mono frame are connected by the above-mentioned end plates. 
     Next, referring to  FIG. 10 , the module frame in the present disclosure may include a U-shaped frame  200   b  and an upper cover  210   b.    
     The U-shaped frame  200   b  may have a structure in which a front surface (X-axis direction), a rear surface (direction opposite to the X-axis), and an upper surface (Z-axis direction) are opened, and it is provided with both side surface ports  212  extending in the upper direction (Z-axis direction) from the bottom part  211  and both opposite ends of the bottom part  211 . 
     The upper cover  210   b  is connected to the opened upper surface of the U-shaped frame  200   b,  and the opened front surface and the opened rear surface of the U-shaped frame  200   b  may be connected by the above-mentioned end plates, respectively. 
     The U-shaped frame  200   b  may be connected to the upper cover  210   b  by welding. Meanwhile, it is preferable that the module frame  200  and the end plate  300  of the present embodiment be a metal plate having a predetermined strength, and in particular, it is preferable to include an aluminum alloy. More specifically, the module frame  200  may include an Al—Mg-based alloy such as Al 5052 or an Al—Mg—Si-based alloy such as Al 6063, and the end plate  300  may include an Al—Si—Cu-based alloy such as ADC12 alloy, or an alloy in which Mg and Mn are added to an Al—Si based alloy such as Silafont-36 alloy. 
     One or more battery modules according to the present embodiment described above may be mounted together with various control and protection systems such as a battery management system (BMS) and a cooling system to form a battery pack. 
     The battery module or the battery pack including the battery module may be applied to various devices. These devices may be applied to transportation means such as an electric bicycle, an electric vehicle, a hybrid vehicle, but the present disclosure is not limited thereto and can be applied to various devices that can use the secondary battery. 
     Although the preferred embodiments of the present disclosure have been described in detail above, the scope of the present disclosure is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present disclosure defined in the following claims also belong to the scope of rights. 
     DESCRIPTION OF REFERENCE NUMERALS 
       100 : battery module 
       200 : module frame 
       250 : first joining surface 
       300 : end plate 
       350 : second joining surface 
       400 : insulator 
       410 : rib