Patent Publication Number: US-2023138854-A1

Title: Method of manufacturing battery module capable of preventing chain ignition

Description:
TECHNICAL FIELD 
     This application claims the benefit of priority to Korean Patent Application No. 2020-0079310 filed on Jun. 29, 2020, the disclosure of which is incorporated herein by reference in its entirety. 
     The present invention relates to a method of manufacturing a battery module capable of preventing chain ignition, and more particularly to a method of manufacturing a battery module capable of preventing chain ignition configured such that heat transfer to adjacent battery cells is inhibited and the weight of the battery module is reduced. 
     BACKGROUND ART 
     With recent development of alternative energies due to air pollution and energy depletion caused as the result of use of fossil fuels, demand for secondary batteries capable of storing electrical energy that is produced has increased. The secondary batteries, which are being capable of being charged and discharged, are intimately used in daily life. For example, the secondary batteries are used in mobile devices, electric vehicles, and hybrid electric vehicles. 
     Required capacities of secondary batteries used as energy sources of various kinds of electronic devices inevitably used in modern society have been increased due to an increase in usage of mobile devices, increasing complexity of the mobile devices, and development of electric vehicles. In order to satisfy demand of users, a plurality of battery cells is disposed in a small-sized device, whereas a battery module including a plurality of battery cells electrically connected to each other or a battery pack including a plurality of battery modules is used in a vehicle. 
     In the battery module or the battery pack, a plurality of battery cells is connected to each other in series or in parallel in order to increase capacity and output of the battery module or the battery pack. In the case in which a plurality of battery cells is used in a state of being connected to each other, a problem, such as overload, may occur. 
     In order to solve this problem, a battery module including a module case capable of inhibiting transfer of heat generated in a specific battery cell to another battery cell adjacent thereto has been developed. 
       FIG.  1    is a perspective view showing a conventional battery module. As shown in  FIG.  1   , the conventional battery module  10  includes a plurality of battery cells  11 , a module case  12  configured to receive the plurality of battery cells  11  therein, and a filler  13  configured to wrap the plurality of battery cells  11  and to fill spaces among the battery cells  11 . 
     In the conventional battery module, the filler  13  is formed among the battery cells  11  received in the module case  12 , whereby the battery cells  11  are disposed spaced apart from each other by a predetermined distance. Consequently, there is an effect that it is possible to inhibit movement of heat generated in a specific battery cell  11  to another battery cell  11  adjacent thereto, whereby it is possible to improve safety of the battery module. 
     Since the battery cells  11  are disposed adjacent to each other, however, filling using the filler  13  is not easy. Furthermore, in the case in which an empty space is generated, it is not possible to sufficiently inhibit heat transfer, and the battery cells are not securely fixed, whereby the battery cells  11  may move even due to weak external impact, which may lead to a major accident. 
     PRIOR ART DOCUMENT 
     (Patent Document 1) Korean Patent Application Publication No. 2019-0132631 
     DISCLOSURE 
     Technical Problem 
     The present invention has been made in view of the above problems, and it is an object of the present invention to provide a method of manufacturing a battery module capable of preventing chain ignition configured such that movement of heat generated in any one of a plurality of battery cells received in the battery module to another battery cell adjacent thereto is inhibited and that the battery cells are securely fixed. 
     It is another object of the present invention to provide a method of manufacturing a battery module capable of preventing chain ignition such that energy density of the battery module is high while the weight of the battery module is reduced. 
     It is a further object of the present invention to provide a method of manufacturing a battery module capable of preventing chain ignition such that manufacturing time is reduced and a product defect rate is reduced. 
     Technical Solution 
     A method of manufacturing a battery module capable of preventing chain ignition according to the present invention to accomplish the above objects includes a step of preparing a module case ( 110 ) having a plurality of receiving portions ( 114 ) formed therein, each of the receiving portions having a space of a predetermined size; a step of receiving a battery cell ( 130 ) in each of the receiving portions ( 114 ); and a step of performing heating to a predetermined temperature to fix the battery cell ( 130 ), wherein the module case ( 110 ) includes a lower plate ( 111 ), a plurality of side plates ( 112 ), and a plurality of partition walls ( 113 ) configured to form the receiving portions ( 114 ), and each of the partition walls ( 113 ) includes a lower partition wall ( 113 ( a )) extending from the lower plate ( 111 ) by a predetermined height and an upper partition wall ( 113 ( b )) extending from the lower partition wall ( 113 ( a )) by a predetermined height. 
     Also, in the battery module manufacturing method according to the present invention, the lower partition wall ( 113 ( a )) and the upper partition wall ( 113 ( b )) may be made of different materials. 
     Also, in the battery module manufacturing method according to the present invention, each of the lower plate ( 111 ), the side plate ( 112 ), and the lower partition wall ( 113 ( a )) of the module case ( 110 ) may be made of a thermoplastic resin, and the upper partition wall ( 113 ( b )) may be made of a thermosetting resin. 
     Also, in the battery module manufacturing method according to the present invention, the thermoplastic resin may be modified polyphenylene ether (mPPE) or polycarbonate (PC), and the thermosetting resin may be at least one of silicon, epoxy, and polyurethane. 
     Also, in the battery module manufacturing method according to the present invention, the upper partition wall ( 113 ( b )) may further include glass bubbles. 
     Also, in the battery module manufacturing method according to the present invention, the module case ( 110 ) may be formed by injection molding. 
     Also, the battery module manufacturing method according to the present invention may further include a step of injecting an adhesive member ( 120 ) into the receiving portions ( 114 ) between the step of preparing the module case ( 110 ) having the plurality of receiving portions ( 114 ) formed therein, each of the receiving portions having the space of the predetermined size, and the step of receiving the battery cell ( 130 ) in each of the receiving portions ( 114 ). 
     Also, in the battery module manufacturing method according to the present invention, the adhesive member ( 120 ) may be a thermosetting resin. 
     Also, in the battery module manufacturing method according to the present invention, the battery cell ( 130 ) may be cylindrical or prismatic. 
     In addition, the present invention provides a battery pack having received therein a battery module ( 100 ) manufactured through the manufacturing method having one or more of the features mentioned above. 
     In addition, the present invention provides a device having the above battery pack mounted therein. 
     Advantageous Effects 
     As is apparent from the above description, a method of manufacturing a battery module capable of preventing chain ignition has a merit in that battery cell receiving portions are formed in a module case in advance, an adhesive member is injected into the receiving portions, and battery cells are received and fixed in the receiving portions, whereby it is possible to greatly reduce manufacturing time. 
     In addition, the method of manufacturing the battery module capable of preventing chain ignition has an advantage in that the thermosetting adhesive member injected into the receiving portions in advance uniformly wraps the outer surfaces of the battery cells in a battery cell receiving process, whereby it is possible to securely fix the battery cells, and therefore impact resistance of the battery module is high. 
     Furthermore, the method of manufacturing the battery module capable of preventing chain ignition has an advantage in that glass bubbles are included in a partition wall configured to partition the battery cells from each other, whereby it is possible to reduce the weight of the battery module, and a thermosetting resin, which is relatively expensive, is less used, whereby it is possible to reduce manufacturing cost. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view showing a conventional battery module. 
         FIG.  2    is a perspective view of a battery module according to a preferred embodiment of the present invention. 
         FIG.  3    is a sectional view taken along line A-A′ of  FIG.  2   . 
         FIG.  4    is a sectional view of a battery cell according to a preferred embodiment of the present invention. 
         FIG.  5    is a flowchart illustrating a battery module manufacturing method according to a preferred embodiment of the present invention. 
         FIG.  6    is a conceptual view illustrating the battery module manufacturing method according to the preferred embodiment of the present invention. 
     
    
    
     BEST MODE 
     Now, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that the preferred embodiments of the present invention can be easily implemented by a person having ordinary skill in the art to which the present invention pertains. In describing the principle of operation of the preferred embodiments of the present invention in detail, however, a detailed description of known functions and configurations incorporated herein will be omitted when the same may obscure the subject matter of the present invention. 
     In addition, the same reference numbers will be used throughout the drawings to refer to parts that perform similar functions or operations. In the case in which one part is said to be connected to another part in the entire specification, not only may the one part be directly connected to the other part, but also, the one part may be indirectly connected to the other part via a further part. In addition, that a certain element is included does not mean that other elements are excluded, but means that such elements may be further included unless mentioned otherwise. 
     Hereinafter, a method of manufacturing a battery module capable of preventing chain ignition according to the present invention will be described with reference to the accompanying drawings. 
       FIG.  2    is a perspective view of a battery module according to a preferred embodiment of the present invention, and  FIG.  3    is a sectional view taken along line A-A′ of  FIG.  2   . 
     Referring to  FIGS.  2  and  3   , the battery module  100  according to the present invention includes a module case  110 , an adhesive member  120 , and a plurality of battery cells  130  received in the module case  110 . 
     First, the module case  110 , which has an approximately hexahedral external shape, includes a flat lower plate  111  and four side plates  112  extending upwards perpendicularly from the edge of the lower plate  111  so as to provide a space in which the plurality of battery cells  130  is received in a state of being spaced apart from each other by a predetermined distance. 
     Here, each of the lower plate  111  and the four side plates  112  may be made of a thermoplastic resin that exhibits predetermined strength in order to protect the received battery cells  130  from external impact, such as modified polyphenylene ether (mPPE) or polycarbonate (PC). However, the material for each plate is not particularly restricted as long as the plate is capable of achieving the same purpose and function. 
     In addition, a partition wall  113  is provided in the space defined by the lower plate  111  and the side plates  112  in order to form a plurality of receiving portions in which the battery cells  130  are separately received. The partition wall  113  may include a lower partition wall  113 ( a ) extending from the lower plate  111  by a predetermined height and an upper partition wall  113 ( b ) extending from the lower partition wall  113 ( a ) by a predetermined height. 
     Here, it is preferable for the lower partition wall  113 ( a ) to be made of the same material as the lower plate  111 , i.e. a thermoplastic resin, such as modified polyphenylene ether (mPPE) or polycarbonate (PC), whereas it is preferable for the upper partition wall  113 ( b ) to be made of a thermosetting resin that exhibits low thermal conductivity and high heat resistance, e.g. at least one of silicon, epoxy, and polyurethane. 
     Consequently, a portion of the lower side of each received battery cell  130  may be supported by the lower partition wall  113 ( a ), which exhibits high stiffness, and heat transfer from the battery cell to another battery cell adjacent thereto may be minimized by the upper partition wall  113 ( b ). Of course, it is obvious that the battery cell  130  may also be fixed and supported by the upper partition wall  113 ( b ). 
     Meanwhile, empty glass bubbles each having a predetermined size may be further included in the upper partition wall  113 ( b ). That is, in the case in which a thermosetting resin, such as silicon, epoxy, or polyurethane, is mixed with glass bubbles to form the upper partition wall  113 ( b ), it is possible to reduce weight of the module case  110 , and the thermosetting resin, which is relatively expensive, is less used, whereby it is possible to reduce manufacturing cost. 
     In addition, an adhesive member  120 , e.g. an adhesive member  120  made of the same material as the upper partition wall  113 ( b ), i.e. a thermosetting resin, may be further provided between the outer surface of the battery cell  130  and the partition wall  113 . 
     Although the adhesive member  120  is shown as being interposed only between the partition wall  113  and the side surface of the battery cell  130  in  FIG.  3   , it is obvious that the adhesive member may also be formed between the lower plate  111  and the bottom surface of the battery cell  130 . 
     Although not particularly restricted, the thickness of the partition wall  113  or the sum of the thickness of the partition wall  113  and the thickness of the adhesive member  120  may be 2 mm or less, preferably 1 mm or less, in order to increase energy density of the battery module. 
       FIG.  4    is a sectional view of a battery cell according to a preferred embodiment of the present invention. The battery cell received in the module case according to the present invention is not restricted to the cylindrical battery cell shown in  FIG.  4   , and may be a prismatic battery cell. 
     When describing the cylindrical battery cell shown in  FIG.  4    by way of example, the battery cell  130  may be manufactured by receiving a wound type electrode assembly  131  in a metal can  132 , injecting an electrolytic solution into the metal can  132 , and coupling a cap assembly  133  having an electrode terminal formed thereon to the open upper end of the metal can  132 . 
     Here, the electrode assembly  131  is manufactured by sequentially stacking a positive electrode  131 ( a ), a negative electrode  131 ( b ), and a separator  131 ( c ) and winding the same so as to have a round shape. 
     A cylindrical center pin  135  is inserted into a hollow core portion  134  formed at a central region of the electrode assembly  131 . The center pin  135  is generally made of a metal material so as to have predetermined strength. The center pin  135  serves to fix and support the electrode assembly  131 , and also serves as a passage configured to discharge gas generated as a result of internal reaction when the battery cell is charged and discharged and when the battery cell is operated. 
     Meanwhile, a positive electrode terminal  133 ( a ) is formed on a central region of the upper end of the cap assembly  133  in a protruding state, and the remaining region of the metal can  132  forms a negative electrode terminal  133 ( b ). 
     Of course, a battery cell usable as a secondary battery is not limited to a cylindrical battery cell  130  having the above construction. 
       FIG.  5    is a flowchart illustrating a battery module manufacturing method according to a preferred embodiment of the present invention, and  FIG.  6    is a conceptual view illustrating the battery module manufacturing method according to the preferred embodiment of the present invention. 
     Referring to  FIGS.  5  and  6   , the battery module manufacturing method according to the preferred embodiment of the present invention includes a step (S 1 ) of preparing a module case having a plurality of receiving portions formed therein, a step (S 2 ) of injecting an adhesive member into the plurality of receiving portions, a step (S 3 ) of receiving a battery cell in each of the receiving portions, and a step (S 4 ) of performing heating to a predetermined temperature to fix the battery cell. 
     First, the step (S 1 ) of preparing the module case having the plurality of receiving portions formed therein is a step of preparing a module case  110  having the above construction, i.e. a module case  110  having a space defined by a lower plate  111  and four side plates  112 , wherein receiving portions  114  are formed in the space by partition walls  113 , each of which includes a lower partition wall  113 ( a ) and an upper partition wall  113 ( b ). 
     Here, it is obvious that the inner diameter of each of the receiving portions  114  must be slightly greater than the outer diameter of a cylindrical battery cell received therein, and glass bubbles are preferably mixed in the upper partition wall  113 ( b ). 
     Meanwhile, it is preferable for the module case  110  to be manufactured as one body by injection molding. As an example, over-molding, multiple injection, or blocking injection molding may be used. However, the molding method is not particularly restricted as long as it is possible to integrate dissimilar materials. In the case in which the above molding method is adopted, there are advantages in that it is possible to form a partition wall  113  having a small thickness and the thickness of the partition wall  113  is uniform. 
     The step (S 2 ) of injecting the adhesive member into the plurality of receiving portions is a step of injecting a predetermined amount of an adhesive member  120  made of a thermosetting material, such as silicon, epoxy, or polyurethane, through an injection portion  200 . 
     The adhesive member  200  fills a gap between a battery cell  130  to be received and the partition wall  113  in order to securely fix the battery cell  130  and to prevent heat transfer to another battery cell  130  adjacent thereto. 
     In the step (S 3 ) of receiving the battery cell in each of the receiving portions, the battery cell  130  is seated in the receiving portion  114  in the state in which the receiving portion  114  is filled with the predetermined amount of the adhesive member  120 . At this time, the adhesive member  120  is pushed upwards to the space between the partition wall  113  and the battery cell  130 , whereby the adhesive member has a shape surrounding the outer circumferential surface of the battery cell  130 . 
     The step (S 4 ) of performing heating to a predetermined temperature to fix the battery cell, which is the last step, is a step of heating the adhesive member  120  to a predetermined temperature at which a thermosetting resin can be hardened for a predetermined time to fix the battery cell  130  to the partition wall  113 . 
     Conventionally, a plurality of battery cells is received in a module case, a thermosetting resin is injected into a space between the battery cells, and the thermosetting resin is hardened, whereby a battery module is manufactured. However, it is not easily to inject the thermosetting resin into a small gap between the battery cells, whereby product defects are incurred and manufacturing time is increased. 
     In the present invention, by contrast, a module case having battery cell receiving portions formed therein is prepared, an adhesive member is injected into the receiving portions, and battery cells are received and hardened, whereby it is possible to very easily form a partition wall that partitions the battery cells. 
     The present invention may provide a battery pack having received therein a battery module manufactured by the battery module manufacturing method having at least one of the features described above. 
     In addition, the present invention may provide a device having the battery pack mounted therein. The device may be an electronic device including a large-capacity battery, such as an electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. 
     Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible within the category of the present invention based on the above description. 
     DESCRIPTION OF REFERENCE SYMBOLS 
     
         
         
           
               100 : Battery module 
               110 : Module case 
               111 : Lower plate  112 : Side plate 
               113 : Partition wall 
               113  ( a ): Lower partition wall  113  ( b ): Upper partition wall 
               114 : Receiving portion 
               120 : Adhesive member 
               130 : Battery cell 
               131 : Electrode assembly 
               131 ( a ): Positive electrode  131 ( b ): Negative electrode 
               131 ( c ): Separator 
               132 : Metal can 
               133 : Cap assembly 
               133 ( a ): Positive electrode terminal  133 ( b ): Negative electrode terminal 
               134 : Core portion 
               135 : Center pin 
               200 : Injection portion