Patent Publication Number: US-2022238964-A1

Title: Battery Module and Battery Pack Including the Same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2021/002256, filed on Feb. 23, 2021, which claims the benefit of Korean Patent Application No. 10-2020-0050725 filed on Apr. 27, 2020 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a battery module and a battery pack including the same, and more particularly to a battery module that improves a molding defect caused by the size increase of a component, and a battery pack including the same. 
     BACKGROUND ART 
     As technology development and demands for mobile devices increase, the demand for batteries as energy sources is rapidly increasing. In particular, a secondary battery has attracted considerable attention as an energy source for power-driven devices, such as an electric bicycle, an electric vehicle, and a hybrid electric vehicle, as well as an energy source for mobile devices, such as a mobile phone, a digital camera, a laptop computer and a wearable device. 
     Small-sized mobile devices use one or several battery cells for each device, whereas middle- or large-sized devices such as vehicles require high power and large capacity. A middle or large-sized battery module is preferably manufactured so as to have as small a size and weight as possible. For this reason, a prismatic battery, a pouch-type battery or the like, which can be stacked with high integration and has a small weight relative to capacity, is usually used as a battery cell of the middle or large-sized battery module. Therefore, a middle or large-sized battery module in which a large number of battery cells are electrically connected is used, and gradually, the need for installing many more battery cells within a battery module is increasing. 
     On the other hand, as the need for the battery module to include many more battery cells is increased, the size of the component included in the battery module also needs to be increased. However, among the components included in the battery module, the component formed by injection molding causes an unmolded section to occur as the size increases. Accordingly, in order to realize the size increase of the battery module, there is a need to improve a molding defect in the unmolded section. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     It is an object of the present disclosure to provide a battery module that can improve a molding defect of a component caused by the size increase of the battery module, and a battery pack including the same. 
     The objects of the present disclosure are not limited to the aforementioned objects, and other objects which are not described herein should be clearly understood by those skilled in the art from the following detailed description and the accompanying drawings. 
     Technical Solution 
     According to one embodiment of the present disclosure, there is provided a battery module comprising a battery cell stack in which a plurality of battery cells are stacked, and a busbar frame located on a front surface or a rear surface of the battery cell stack, wherein the busbar frame comprises a support part surrounding at least a portion of a bottom surface of the battery cell stack, and wherein the support part comprises an extension region extending from the busbar frame in a lengthwise direction of a battery cell of the plurality of battery cells, and a protrusion region on the extension region. 
     The protrusion region may include at least two protrusion regions, with each protrusion region of the at least two protrusion regions being spaced apart from each other in a direction corresponding to a direction in which the plurality of battery cells are stacked. 
     The protrusion region may be at a location corresponding to where an unmolded section would be disposed in the support part. 
     The protrusion region may be at a location corresponding to a region between two of the plurality of battery cells in the battery cell stack. 
     The protrusion region may be protruded from the extension region toward the battery cell stack. 
     The protrusion region may have a symmetrical shape. 
     At least one layer of the protrusion region may be stacked on the extension region. 
     At least two layers of the protrusion region may be stacked on the extension region, with a length of a layer of the at least two layers adjacent to the extension region being longer than lengths of other layers of the at least two layers. 
     The length of the layer adjacent to the extension region may be identical to or smaller than a region between two of the plurality of battery cells in the battery cell stack. 
     A thickness of the extension region may be smaller than a thickness of a location of the support part at which the protrusion region is disposed. 
     According to one embodiment of the present disclosure, there is provided a battery pack comprising the above-mentioned battery module. 
     Advantageous Effects 
     According to the embodiments of the present disclosure, the molding defect caused when the busbar frame is injection-molded can be improved by reinforcing a thickness of a partial section of the busbar frame according to the size increase of the battery module. 
     Further, an application amount of the thermally conductive resin can be prevented from being increased due to an increase in the entire thickness, through a partial reinforcement of the thickness of the busbar frame. 
     The effects of the present disclosure are not limited to the effects mentioned above and additional other effects not described above will be clearly understood from the description of the appended claims by those skilled in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view illustrating a battery module according to an embodiment of the present disclosure; 
         FIG. 2  is a perspective view illustrating a state in which elements constituting the battery module of  FIG. 1  are coupled to each other; 
         FIG. 3  is a view illustrating a busbar frame in a battery module according to a comparative example. 
         FIG. 4  is a view illustrating a molding defect section in the busbar frame of  FIG. 3 ; 
         FIG. 5  is a view illustrating a busbar frame in the battery module according to the embodiment of the present disclosure; 
         FIG. 6  is an enlarged view of region A of  FIG. 5 ; 
         FIG. 7  is a view illustrating a cross-section taken along an xy plane of  FIG. 2 ; 
         FIG. 8  is a sectional view of region B of  FIG. 7 , taken along the cutting line a-a′; 
         FIG. 9  is a sectional view of region B of  FIG. 8 , taken along the cutting line b-b′; and 
         FIG. 10  is a sectional view of region B of  FIG. 8 , taken along the cutting line c-c′. 
     
    
    
     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 carry out 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. 
     In the following, an electrode for a secondary battery according to an embodiment of the present disclosure will be described. However, the description herein is made based on the front surface of the front and rear surfaces of the battery module, but is not necessarily limited thereto, and even in the case of the rear surface, the same or similar contents may be described. 
       FIG. 1  is an exploded perspective view illustrating a battery module according to an embodiment of the present disclosure.  FIG. 2  is a perspective view illustrating a state in which elements constituting the battery module of  FIG. 1  are coupled to each other. 
     Referring to  FIGS. 1 and 2 , a battery module  100  according to the present embodiment includes a battery cell stack  120  in which a plurality of the battery cells  110  are stacked, a module frame  200  for housing the battery cell stack  120 , and end plates  150  for covering front and rear surfaces of the battery cell stack  120 . Further, the battery module  100  further includes a busbar frame  130  located between the end plates  150  and the battery cell stack  120 . 
     As an example, the module frame  200  includes a U-shaped frame  300 , of which an upper surface, a front surface, and a rear surface are opened, and an upper plate  400  for covering an upper part of the battery cell stack  120 . However, the module frame  200  is not limited thereto and may be replaced by a frame of another shape, such as an L-shaped frame or a mono frame surrounding the battery cell stack  120  excluding front and rear surfaces thereof. 
     The busbar frame  130  may include parts surrounding lower ends of the front and rear surfaces of the battery cell stack  120  stacked in parallel, thereby protecting the battery cell stack  120  from an external impact and improving the insulation performance of the battery cell stack  120 . 
     However, the battery module  100  according to an embodiment of the present disclosure includes a large-area module in which the battery cell stack  120  includes a relatively larger number of battery cells as compared with the existing battery module. In the case of the large-area module, the horizontal length of the battery module becomes relatively longer. Here, the horizontal length of the battery module may mean a length in a direction in which the battery cells are stacked. 
     Hereinafter, the busbar frame  130  included in the battery module  100  according to an embodiment of the present disclosure will be described in detail in comparison with a comparative example. 
       FIG. 3  is a view illustrating a busbar frame in a battery module according to a comparative example.  FIG. 4  is a view illustrating a molding defect section in the busbar frame of  FIG. 3 . 
     Referring to  FIGS. 3 and 4 , the busbar frame  13  included in the battery module (not illustrated) has a support part  14  that can surround at least a partial region of bottom surfaces of the front and rear surfaces of the battery cell stack (not illustrated). The support part  14  is extended from the busbar frame  13  in a direction that is perpendicular to the busbar frame  13 . 
     However, in order to mount a busbar frame  13  on the large-area module, the busbar frame  13  also have to be increased in size as it progresses in a horizontal direction of the battery module, and accordingly, the support part  14  of the busbar frame  13  also has to be increased in size. Referring to  FIG. 4 , when the upsized busbar frame  13  is injection-molded, an unmolded section  14   a  may be caused in a partial region of the support part  14 . Here, the unmolded section  14   a  means that the partial region of the support part  14  is not subjected to injection molding due to a thin thickness of the support part  14 . 
     In order to prevent the unmolded section  14   a  of the support part  14  from occurring, when an entire thickness of the support part  14  increases, a total weight of the busbar frame  13  due to the support part  14  increases and thus, a load applied to the frame  200  may increase and damage may be caused due to weight. Further, in this case, because the battery cell stack supported by the support part  14  also becomes far away from a bottom part of the module frame due to the increase in thickness of the support part  14 , an application amount of a thermally conductive resin, which is used to form the thermally conductive resin layer between the battery cell stack and the module frame, may also increase. Accordingly, the total weight of the module and thermal resistance increase, heat generation caused from the battery cell stack  120  is not sufficiently discharged to the outside, and the danger of a fire due to heat generation may increase. Further, as the application amount of the thermally conductive resin increases, the manufacturing costs and the manufacturing time may increase. 
     Thus, in the embodiment of the present disclosure, at the time of forming the upsized busbar frame  130  for being mounted on the large-area module by injection molding, the busbar frame, which is configured to prevent formation of a part such as unmolded section  14   a  of the support part  14  according to the above-mentioned comparative example, will be described. 
       FIG. 5  is a view illustrating a busbar frame in the battery module according to the embodiment of the present disclosure.  FIG. 6  is an enlarged view of region A of  FIG. 5 . 
     Referring to  FIGS. 1, 2, 5, and 6 , the busbar frame  130  included in the battery module  100  may have the support part  140  that can surround at least a partial region of bottom surfaces of the front and rear surfaces of the battery cell stack  120 . In particular, each of the battery cells  110  of the battery cell stack  120  may include a protrusion (not illustrated) that faces the bottom surface of the frame  100 , and the support part  140  can surround the protrusions (not illustrated) formed in the battery cells  110 . Accordingly, the support part  140  can protect the protrusion (not illustrated) from an external impact and can improve the insulation performances of the battery cells  110 . 
     The support part  140  is extended from the busbar frame  130  in a lengthwise direction of the battery cells. Further, the support part  140  is extended so as to surround the bottom surfaces of the front and rear surfaces of the battery cell stack  120 . Further, the support part  140  is extended so as to surround the protrusions (not illustrated) formed in the battery cells  110  of the battery cell stack  120 . 
     The support part  140  may include an extension region  141  and at least two protrusion regions  145  formed on the extension region  141 . The extension region  141  may be a region extending from the busbar frame  130  in a direction that is perpendicular to the busbar frame  130 . The protrusion regions  145  are regions protruding from the extension region  141  toward the battery cell stack  120 . At least two protrusion regions  145  may be spaced apart from each other in a direction in which the battery cells  110  of the battery cell stack  120  are stacked. Here, the protrusions region  145  can perform the role of reinforcing a thickness of the extension region  141 . 
     The support part  140  may be injection-molded, and the extension region  141  and the protrusion regions  145  may also be integrally injection-molded. The support part  140  needs to maintain the thin thickness in order to reduce a load that is applied to the frame  200 , reduce the application amount of an insulation substance applied to the frame  200 , and have a proper thermal resistance. However, as the busbar frame  130  is injected by further extending in a staking direction of the battery cell stack so as to be mounted on the large-area module, the extension region  141  is also injected by further extending in the stacking direction of the battery cell stack. Accordingly, as the extension region  141  maintains the thin thickness and also extends in the stacking direction of the battery cell stack more than the existing length, the unmolded section  14   a  as shown in  FIG. 4  may occur. 
     Referring to  FIGS. 1, and 4 to 6 , in order to prevent the unmolded section  14   a  as in  FIG. 4  from occurring during injection molding of the support part  140 , the protrusion regions  145  may be partially formed in a section in which there is a high possibility of causing the unmolded section  14   a  to occur in the extension region  141 . Further, the protrusion regions  145  may be formed at locations corresponding to where the unmolded section would be formed in the extension region  141 . Further, in order to prevent the unmolded section  14   a  from occurring in the extension region  141 , the protrusion regions  145  may be formed to be spaced apart from each other at a regular interval on the extension region  141 . 
     Accordingly, while the support part  140  included in the upsized busbar frame  140  maintains the thin thickness, the thickness of a partial section of the extension region  141  may be reinforced due to the protrusion region  145 . That is, while the support part  140  does not increase the thickness of the extension region  141 , a vulnerable portion due to unmolding due to the widened areas may be supplemented by the protrusion region  145 . Further, the protrusion region  145  may be integrally molded as the busbar frame  140  is injection-molded, and thus the method for manufacturing may become simpler and the manufacturing time may become shorter. 
       FIG. 7  is a view illustrating a cross-section taken along an xy plane of  FIG. 2 .  FIG. 8  is a sectional view of region B of  FIG. 7 , taken along the cutting line a-a′. 
     Referring to  FIGS. 1, and 5 to 8 , the support part  140  may have the extension region  141  and the protrusion region  145 , and the protrusion regions  145  may be formed at the location corresponding to a region between at least two battery cells  110 . As an example, each of the battery cells  110  of the battery cell stack  120  includes a protrusion  110 P. The protrusion regions  145  may be formed at the location corresponding to the region between the protrusions  110 P formed at two or more of the battery cells  110 , respectively. 
     Accordingly, the support part  140  forms the protrusion region  145  in order to prevent the unmolded section due to the increase of size, and forms the protrusion region  145  at the location corresponding to the region between the protrusions  110 P of the battery cells  110  to thereby minimize an empty space between the support part  140  and the battery cell stack  120 . Further, the protrusion region  145  of the support part  140  may also protect side surfaces of the protrusion  110 P and thus, protection performance from the external impact about the protrusion  110 P of the battery cell  110  can be improved. Further, because an empty space between the support part  140  and the battery cell stack  120  is minimized and thus, the thickness of the thermally conductive resin layer applied to the frame  200  can be maintained similar to the existing thickness thereof, the total weight and thermal resistance may not increase. 
     Referring to  FIGS. 1, and 5 to 8 , the protrusion region  145  may have a symmetrical shape. Further, the protrusion region  145  may have a region in which at least one layer is formed to be curved on the extension region  141 . Further, the protrusion region  145  may have a region in which at least one layer is formed to be stacked on the extension region  141 . In particular, the region formed through stacking may be smoothly connected to the extension region  141 . Here, the protrusion region  145  may have a region in which at least one layer having shorter length as compared with the extension region  141  is formed on the extension region  141 . Further, the protrusion region  145  may be formed by stacking at least two layers, the length of at least two layers is smaller as compared with the extension region  141 , and the length of a layer adjacent to the extension region  141  may be formed longer. Further, when the protrusion region  145  is formed at the location corresponding to a region between the protrusions  110 P, the protrusion region  145  may be identical to or smaller than a region between two battery cells  110 . 
     Accordingly, the protrusion region  145  may be formed in the support part  140  to prevent an unmolded section according to the increase of size, and when the protrusion region  145  is injection-molded, the manufacturing process may become simple and the manufacturing time may become shorter. 
       FIG. 9  is a sectional view of region B of  FIG. 8 , taken along the cutting line b-b′.  FIG. 10  is a sectional view of region B of  FIG. 8 , taken along the cutting line c-c′. 
     Referring to  FIGS. 1, and 5 to 10 , the support part  140  may be configured such that a thickness h 1  of the extension region  141  is smaller as compared with a thickness h 2  of the support part at the location in which the protrusion region  145  is formed. This is because the extension region  141  surrounds the protrusion  110 P formed at the battery cell  110  of the battery cell stack  120  and thus, must have a thin thickness as compared with the protrusion region  145 . Accordingly, the support part  140  corresponds to the extension region  141  and a lower surface of the protrusion  110 P, and the protrusion region  145  corresponds to the side surfaces of the protrusion  110 P and thus, the protection performance from an external impact about the protrusion  110 P of the battery cell  110  can be improved. 
     Therefore, according to the invention described herein, despite the expansion of the area of the support part  140  due to the size increase of the busbar frame  130 , not only the protection and insulation performances of the protrusion  110 P of the battery cell  110 , which are the existing purposes of the support part  140 , can be realized, but also through the protrusion region  145 , the unmolded section of the support part  140  can be reinforced, the rigidity can be improved, and the protection of the protrusion  110 P can be strengthened. 
     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 
       110 : battery cell 
       120 : battery cell stack 
       130 : busbar frame 
       140 : support part 
       200 : module frame