Patent Publication Number: US-2023144655-A1

Title: Method for manufacturing battery module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a National Stage Application of International Application No. PCT/KR2021/009872, filed on Jul. 29, 2021, which claims priority to and the benefit of Korean Patent Application No. 10-2020-0094336 filed on Jul. 29, 2020, and Korean Patent Application No. 10-2021-0095773 filed on Jul. 21, 2021, the disclosures of which are incorporated herein by reference in their entireties. 
    
    
     FIELD OF DISCLOSURE 
     The present disclosure relates to a method for manufacturing a battery module, and more particularly, to a method for manufacturing a battery module which may minimize an error caused by an operator during a process of manufacturing the battery module. 
     BACKGROUND 
     There has been increasing technology development and demand for a mobile device, and demand for a secondary battery as an energy source is thus rapidly increasing. Accordingly, many studies have been conducted on the secondary battery which may meet various needs. 
     The secondary battery is spotlighted as the energy source for a power device such as an electric bicycle, an electric vehicle or a hybrid electric vehicle, as well as a mobile device such as a mobile phone, a digital camera or a laptop computer. 
     A small battery pack in which one battery cell is packed may be used for a small device such as the mobile phone or the camera. However, a medium-sized or large-sized battery pack, which is a battery pack having two or more battery cells connected in parallel and/or in series with each other, may be used for a mid- to large-sized device such as the laptop computer or the electric vehicle. Accordingly, the number of battery cells included in the battery pack may be variously set based on required output voltage or charge/discharge capacity. 
     Meanwhile, the battery pack may be formed by connecting the plurality of battery cells in series/parallel with each other. In this case, the battery pack may be generally formed by first forming at least one battery module including the battery cells, and then adding other components thereto by using the at least one battery module. 
     In the case of such a battery module, there is a gradually emerging importance of technology which may efficiently cool heat occurring in the battery cell as the required battery capacity is increased. To this end, introduced is a structure which may improve thermal conductivity of the battery module by applying a resin for heat dissipation to the inside of a case of the battery module. 
     However, when the resin is injected into the case of such a battery module through an injection hole, a manufacturing process may be carried out in a state in which a lower surface of the battery module is turned upside down, thus making it difficult to check a condition of the battery module, included in its upper surface, etc. For this reason, defects may often occur by finishing the process in a state where the resin is not sufficiently cured. 
     SUMMARY 
     An exemplary embodiment of the present disclosure provides a method for manufacturing a battery module, which may minimize a process error caused by an operator by making it easy to check a process condition of an injected resin or the like even during processes of injecting the resin into the battery module and curing the same. 
     However, technical problems to be solved by an exemplary embodiment of the present disclosure are not limited to the aforementioned problems, and may be variously expanded in the scope of a technical idea included in the present disclosure. 
     According to an exemplary embodiment of the present disclosure, a method for manufacturing a battery module includes: forming a battery cell stack by stacking a plurality of plate-shaped battery cells parallel and adjacent to each other; accommodating the battery cell stack in a module frame including four plates surrounding at least four surfaces of the battery cell stack; attaching adhesive tapes to perimeters of an injection hole and of an observation hole formed in a lower plate among the four plates; injecting a thermal conductive resin solution through the injection hole; and writing injection information of the injecting a thermal conductive resin solution on at least a portion of the adhesive tapes. 
     The method may further include curing the thermal conductive resin solution based on the injection information after injecting the thermal conductive resin solution, and then removing the adhesive tapes. 
     Curing time of the thermal conductive resin solution may be one hour to two hours. 
     The injection hole may include at least two holes formed in a central portion of the lower plate in a length direction. 
     The observation hole may be spaced apart from the injection hole in a length direction of the lower plate and positioned at each of two ends of the lower plate in the length direction. 
     The thermal conductive resin solution may be a thermal resin. 
     The thermal conductive resin solution may be cured to form a thermal conductive resin layer between the battery cell stack and the lower plate. 
     The injection of the thermal conductive resin solution may be performed until the thermal conductive resin solution is observed through the observation hole. 
     The adhesive tapes may have holes respectively corresponding to the observation hole and the injection hole, and the excess thermal conductive resin solution overflown out of the injection hole or the observation hole may also be removed by removing the adhesive tapes. 
     The injection information of the injecting a thermal conductive resin solution may include injection time of the injecting a thermal conductive resin solution. 
     The adhesive tapes may be transparent, and attached so as to block the observation hole. 
     The adhesive tapes may have a characteristic changed by temperature change or time elapse. 
     The characteristic may be at least one of color or transparency of the adhesive tapes. 
     The writing injection information may be performed with an ink, and the ink may have a characteristic changed by temperature change or time elapse. 
     The characteristic may be at least one of color or transparency of the ink. 
     Advantageous Effects 
     As set forth above, an exemplary embodiment of the present disclosure may provide the method for manufacturing a battery module, which may minimize the process error caused by the operator by making it easy to check the process condition of the injected resin or the like even during the processes of injecting the resin into the battery module and curing the same. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIGS.  1  to  6    are views each showing a method for manufacturing a battery module according to an exemplary embodiment of the present disclosure. 
         FIG.  7    is a view showing a portion of a cross section taken along line A-A′ of  FIG.  5   . 
         FIGS.  8 A and  8 B  are cross-sectional views showing a portion of a cross section taken along line B-B′ of  FIG.  6    respectively in an exemplary embodiment of the present disclosure and a comparative example. 
         FIG.  9    is a cross-sectional view showing a portion of a cross section taken along line B-B′ of  FIG.  6    in another exemplary embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present disclosure are described in detail with reference to the accompanying drawings so that those skilled in the art to which the present disclosure pertains may easily practice the present disclosure. The present disclosure may be implemented in various different forms and is not limited to exemplary embodiments provided herein. 
     A portion unrelated to the description is omitted in order to obviously describe the present disclosure, and the same or similar components are denoted by the same reference numeral throughout the present specification. 
     In addition, the size and thickness of each component shown in the accompanying drawings are arbitrarily shown for convenience of explanation, and therefore, the present disclosure is not necessarily limited to contents shown in the accompanying drawings. The thicknesses are exaggerated in the drawings in order to clearly represent several layers and regions. In addition, in the drawings, the thicknesses of some layers and regions are exaggerated for convenience of explanation. 
     In addition, when an element such as a layer, a film, a region, or a substrate is referred to as being “on” or “above” another element, it may be “directly on” another element or may have a third element interposed therebetween. On the contrary, when an element is referred to as being “directly on” another element, there is no third element interposed therebetween. In addition, when an element is referred to as being “on” or “above” a reference element, it may be positioned on or below the reference element, and it may not necessarily be “on” or “above” the reference element toward an opposite direction of gravity. 
     In addition, throughout the present specification, unless explicitly described to the contrary, “including” any components may be understood to imply the inclusion of other elements rather than the exclusion of any other elements. 
     Further, throughout the specification, the word “on the plane” may indicate a case where a target is viewed from the top, and the word “on the cross section” may indicate a case where a cross section of a target taken along a vertical direction is viewed from the side. 
       FIGS.  1  to  6    are views each showing a method for manufacturing a battery module according to an exemplary embodiment of the present disclosure; and  FIG.  7    is a view showing a portion of a cross section taken along line A-A′ of  FIG.  5   . 
     Referring to  FIG.  1   , a battery module  100  according to an exemplary embodiment of the present disclosure may be manufactured by forming a battery cell stack  110  by stacking a plurality of plate-shaped battery cells  112  parallel and adjacent to each other and then by accommodating the battery cell stack  110  in a module frame  120  including four plates surrounding at least four surfaces of the battery cell stack  110 . 
     The battery cell stack  110  may be a secondary battery assembly including the plurality of battery cells  112 . The battery cell stack  110  may include the plurality of battery cells  112 , and each battery cell may include an electrode lead  114 . The battery cell stack  110  may be formed by stacking the plurality of battery cells  112  on each other and connecting the battery cells with each other by using the electrode lead  114 . The battery cell  112  may be a pouch-type battery cell having a plate shape, and is not limited thereto. The electrode lead  114  may be a positive electrode lead or a negative electrode lead. Here, an end of the electrode lead  114  of each battery cell  112  may be bent in one direction, and may thus come into contact with the end of the electrode lead of another battery cell  112  adjacent thereto. The two electrode leads  114  in contact with each other may be fixed to each other through welding or the like, thereby making the battery cells  112  in the battery cell stack  110  be electrically connected to each other. 
     The plurality of battery cells  112  may be vertically stacked on each other so that the electrode leads  114  are aligned in one direction to form the battery cell stack  110 . The battery cell stack  110  may have at least one opening  128  open in a length direction of the battery cell stack  110 , and may be accommodated in the module frame  120  including the four plates surrounding at least four surfaces of the battery cell stack  110 . For example, the module frame  120  may have an upper plate  121  and a lower plate  126 , which are perpendicular to a surface on which the battery cell stack  110  is mounted, and a pair of side plates  124  which are parallel to the surface on which the battery cell stack  110  is mounted. In addition, this exemplary embodiment describes an example of the module frame  120  having a square tube in which the upper plate  121 , the lower plate  126  and the pair of side plates  124  are integrally formed with each other, and the present disclosure is not limited thereto. The present disclosure may also use the module frame  120  formed so that three surfaces thereof form a U-shaped frame and a plate forming the other surface covers an open surface of the U-shaped frame. 
     The lower plate  126  of the module frame  120  may include a plurality of injection holes  125  (shown in  FIG.  3   ) for injecting a thermal conductive resin solution  122  (shown in  FIG.  7   ) for forming a thermal conductive resin layer  122 ′ (shown in  FIGS.  8 A and  8 B ) for heat dissipation, which is described below. 
     Next, referring to  FIG.  2   , an end plate  130  may be coupled to the opening  128  of the module frame  120 . The end plate  130  may include a component electrically connecting the electrode lead  114  to the outside. 
     Next, referring to  FIG.  3   , the battery module  100  may be inverted so that the lower plate  126  of the module frame  120  faces upward. 
     At least one injection hole  125  and at least one observation hole  123  may be formed in the lower plate  126 . At least one injection hole  125  may be formed in a central portion of the lower plate  126 , and the thermal conductive resin solution  122  may be injected through the injection hole  125  formed in the central portion, flow to both side portions of the lower plate, and thus be entirely spread over and applied to a space between the lower plate  126  and the battery cell stack  110 . Here, the observation hole  123  may be formed at each of two ends of the lower plate  126  in the length direction to check whether the thermal conductive resin solution  122  is sufficiently injected.  FIG.  3    shows that one observation hole  123  is formed in a portion adjacent to each of two ends, and the present disclosure is not limited thereto. Two or more observation holes  123  may be formed in the lower plate  126  in a width direction, and appropriately selected based on a size of the battery module  100 . 
     Next, referring to  FIG.  4   , adhesive tapes  210  and  220  may respectively be attached to perimeters of the injection hole  125  and the observation hole  123  of the lower plate  126 . 
     The adhesive tapes  210  and  220  attached to the perimeters of the injection hole  125  and observation hole  123  may include holes respectively corresponding to the injection hole  125  and the observation hole  123 . These adhesive tapes  210  and  220  may be removed after an injection process and a curing process are finished, and here, the excess thermoplastic resin solution  122  overflown out of the hole may also be removed. That is, the adhesive tapes  210  and  220  may serve as a kind of masking tapes. 
     Next, referring to  FIGS.  5  and  7   , the thermal conductive resin solution  122  may be injected through the injection hole  125 , and injection information of the injecting a thermal conductive resin solution  122  may be written on at least a portion of the adhesive tapes  210  and  220 . 
     The thermal conductive resin solution  122  may form the thermal conductive resin layer  122 ′ made of a thermal conductive material to dissipate heat occurring in the battery cell stack  110  to the outside, and may be made of thermal resin for example. An example of the thermal resin may be silicone, urethane, epoxy or the like. 
     The thermal conductive resin solution  122  may be injected through the injection hole  125 , and whether an injection amount is sufficient may be determined by observing, through the observation hole  123 , whether the thermal conductive resin solution  122  arrives at either end of the lower plate  126  in the length direction. 
     The thermal conductive resin solution  122  injected in a liquid state may be naturally cured after the injection is completed to form the thermal conductive resin layer  122 ′. Here, when the adhesive tapes  210  and  220  are removed while curing time is not sufficiently elapsed, an incomplete filling phenomenon may occur in which the thermal conductive resin solution  122  fails to sufficiently fill the space between the lower plate  126  and the battery cell stack  110 . That is, as shown in  FIG.  7   , a portion of the thermal conductive resin solution  122  may flow out of the hole such as the observation hole  123  and then be cured while permeating into the hole again during the curing process, thereby completely filling the inside of the hole. Here, when the adhesive tapes are removed after insufficient curing time, the incomplete filling phenomenon may occur. 
     Therefore, in order to prevent an error in removing the adhesive tapes  210  and  220  before the sufficient curing time is elapsed, the injection information of the injected thermal conductive resin solution  122  may be written on at least a portion of the adhesive tapes  210  and  220 , for example, the adhesive tape  210  attached to the perimeter of any one observation hole  123 , as shown in  FIG.  5   . Here, injection date and injection time may be written as the injection information for example. The injection information may be written on the adhesive tape  220  in the perimeter of the injection hole  125 . However, it may be more preferable to write the information on the adhesive tape  210  in the perimeter of the observation hole  123  which may secure a wider area. It may be possible to check whether the sufficient curing time is elapsed after checking the written injection information in this step, and then perform the next step, thereby preventing the incomplete filling due to an error caused by an operator, etc. 
     In particular, as shown in  FIG.  5   , the injection and curing of the thermal conductive resin solution  122  may be performed in a state where the lower plate  126  is inverted to face upward. The information on the battery module  100  may thus be checked while being inverted in this way, thus making it easier to classify, manage, and identify the product in a semi-finished state. 
     The curing time may be taken one hour to two hours so that the thermal conductive resin solution  122  may be completely cured by the natural curing, is not limited thereto, and may be appropriately adjusted based on the type and amount of the injected thermal conductive resin. Accordingly, not only the injection time but also the type and amount of the injected resin may be written on the adhesive tape  210 , and the present disclosure is not particularly limited thereto. 
     In addition, the adhesive tapes  210  and  220  may each be a tape having its own characteristic in which its color or transparency is changed by time elapse, or a tape having a characteristic in which its color or transparency is changed by temperature change. Accordingly, even if the operator does not write the injection information by mistake, it may be inferred how much time is elapsed or how much the curing of the inner thermal conductive resin solution  122  is progressed based on the change in the color or transparency of the adhesive tape  210  or  220 , thereby doubly preventing the process error. Here, in order to more accurately check the change in color of the adhesive tape  210  or  220  over time, the operator may check a color change table over time or the like after the attachment of the adhesive tape  210  or  220 . In addition, the thermal conductive resin solution  122  may be mixed while being injected into the module through a nozzle, have a slight temperature rise as a reaction occurs during its mixing, and then return to its original temperature when the curing is completed. Accordingly, the curing time may be inferred by using the adhesive tapes  210  and  220  which are sensitive to this temperature difference. 
     In addition to the adhesive tapes  210  and  220 , an ink for marking on the adhesive tapes  210  and  220  may have a characteristic in which its color is changed by time elapse or temperature change. It is thus possible to doubly check process information by using such an ink. 
     Next, referring to  FIGS.  6 ,  8 A and  8 B , the battery module  100  including the thermal conductive resin layer  122 ′ may be completed by removing the adhesive tapes  210  and  220  after completing the curing of the thermal conductive resin solution  122 . 
     Here, some of the resin solution flowing out through the observation hole  123  and the injection hole  125  and then cured may also be removed together with the adhesive tapes  210  and  220 , and it is thus possible to complete the battery module  100  having a neat appearance. In particular, in an exemplary embodiment of the present disclosure in which the adhesive tapes  210  and  220  are removed after the sufficient curing time is elapsed by utilizing the injection information written on the adhesive tape  210 , the thermal conductive resin layer  122 ′ is formed to sufficiently fill the space between the lower plate  126  and the battery cell stack  110  as shown in  FIG.  8 A , thereby preventing the incomplete filling phenomenon. On the other hand, unlike an exemplary embodiment of the present disclosure, when the adhesive tapes  210  and  220  are removed before the curing is completed without checking the injection information, a defect may occur in which the thermal conductive resin layer  122  fails to sufficiently fill the space between the lower plate  126  and the battery cell stack  110  and has a partial depression as shown in  FIG.  8 B , etc. In this case, it may be difficult to rework to fill the corresponding portion with the thermal conductive resin solution, and it may take excessive time for classify and inspecting the defect. According to an exemplary embodiment of the present disclosure, it is possible to prevent the occurrence of such a defect in advance, and it is thus possible to easily and accurately manage and identify the injection process of the thermal conductive resin solution. 
     Hereinafter, the description describes a method for manufacturing a battery module according to another exemplary embodiment of the present disclosure with reference to  FIG.  9   . 
     Another exemplary embodiment of the present disclosure omits the description of the same part as that of the method for manufacturing a battery module according to an exemplary embodiment described above, and only describes a different part. 
       FIG.  9    is a cross-sectional view showing a portion of a cross section taken along line B-B′ of  FIG.  6    in another exemplary embodiment of the present disclosure. 
     Referring to  FIG.  9   , another exemplary embodiment of the present disclosure is the same as an exemplary embodiment described above, except that an adhesive tape  210 ′ attached to the observation hole  123  is a transparent tape blocking the observation hole  123 . The transparent adhesive tape  210 ′ may be attached to the observation hole  123 , and it is thus possible to observe whether the resin solution is injected. In addition, the observation hole  123  may be blocked from the outside by the adhesive tape  210 ′. Accordingly, the thermoplastic resin solution  122  does not leak to the outside, and may be moved into the lower plate  126  again by adhesive pressure of the adhesive tape  210 ′. The resin composition may thus be evenly spread even to the most distal end of the lower plate  126 . 
     In addition, the information on the thermoplastic resin solution  122  injected into the transparent adhesive tape  210 ′ may be written and the curing time may be controlled by checking the information, thereby making it possible to remove the adhesive tape  210 ′ after the sufficient curing is achieved. Even in this exemplary embodiment, when the adhesive tape  210 ′ is removed before the sufficient curing time is elapsed, an uncured portion may be attached to and removed from the adhesive tape  210 ′ through the hole, resulting in the incomplete filling problem. However, it is possible to prevent the occurrence of the defect due to the incomplete filling by writing the information on the injected thermoplastic resin solution  122  on the transparent adhesive tape  210 ′ and checking the information to secure the sufficient curing time. 
     Although the exemplary embodiments of the present disclosure have been described in detail hereinabove, the scope of the present disclosure is not limited thereto. That is, various modifications and alterations made by a person of ordinary skill in the art by using a basic concept of the present disclosure as defined in the following claims fall within the scope of the present disclosure. 
     DESCRIPTION OF REFERENCE NUMERALS 
     
         
         
           
               100 : battery module 
               110 : battery cell stack 
               120 : module frame 
               122 : thermosetting resin solution 
               123 : observation hole 
               125 : injection hole 
               210 ,  220 : adhesive tape