Abstract:
A battery pack including a battery cell including an electrode assembly arranged within a can and an electrode terminal electrically connected to the electrode assembly, the can having an opening sealed by a cap plate, a top case attached to the battery cell at a top portion of the battery cell, the top case having an inner space and a protective circuit module including a protection circuit board arranged within said inner space of said top case and electrically connected to the electrode assembly, wherein the top case includes a top portion opposite from the electrode assembly and first and second pairs of opposed sides, the first pair of opposed sides having an edge, a portion of the edge has a recessed interference preventing portion, the recessed interference preventing portion corresponds to a location of a weld connecting an electrode tap to the electrode terminal.

Description:
CLAIM OF PRIORITY 
       [0001]    This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for BATTERY PACK earlier filed in the United States Patent &amp; Trademark Office on Nov. 16, 2010 and there duly assigned Ser. No. 61/414,079. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    One or more embodiments of the present invention relates to a battery pack in which a top case including a protection circuit module (PCM) is coupled to a battery cell. 
         [0004]    2. Description of Related Art 
         [0005]    Unlike primary batteries, secondary batteries are chargeable and dischargeable. Secondary batteries are used as energy sources for small-sized devices, such as cellular phones, laptop computers, and camcorders, and medium-large sized devices such as electric cars, hybrid electric cars, electric bicycles, and uninterruptible power supplies (UPS). 
         [0006]    A lithium secondary battery is an example of the secondary battery. The lithium secondary battery may be classified into a can-type secondary battery, which has a cylindrical and square pillar shape, and a pouch-type secondary battery having flexibility according to the shape of a case accommodating an electrode assembly. 
         [0007]    Conventionally, a battery cell accommodating an electrode assembly is electrically connected to a protection circuit module (PCM). The PCM includes a plurality of electrode taps. In a secondary battery having a square pillar shape, a positive electrode tap is electrically connected to a can or cap plate of a battery cell, and a negative electrode tap is electrically connected to an electrode terminal of the battery cell. The PCM is installed in a top case, and the top case is coupled to the battery cell. 
         [0008]    In a battery pack having a structure as described above, there is a need to reduce assembly errors, such as defects in welding, which may be caused during a process of assembling components when a top case is coupled to a battery cell. 
       SUMMARY OF THE INVENTION 
       [0009]    One or more embodiments of the present invention include a battery pack in which a top case including a protection circuit module (PCM) is coupled to a battery cell. 
         [0010]    According to one or more embodiments of the present invention, there is provided a battery pack that includes a battery cell including an electrode assembly arranged within a can and an electrode terminal electrically connected to the electrode assembly, the can having an opening sealed by a cap plate, a top case attached to the battery cell at a top portion of the battery cell, the top case having an inner space and a protective circuit module including a protection circuit board arranged within said inner space of said top case and electrically connected to the electrode assembly, wherein the top case may include a top portion opposite from the electrode assembly and first and second pairs of opposed sides, the first pair of opposed sides having an edge, wherein a portion of the edge may have a recessed interference preventing portion, wherein the recessed interference preventing portion corresponds to a location of a weld connecting an electrode tap to the electrode terminal. 
         [0011]    The first pair of opposed sides of the top case may be longer than the second pair of opposed sides. Each of the sides of the first pair of opposed sides may include an edge having a recessed interference preventing portion. The electrode tap may electrically connect the electrode terminal to the protection circuit board of the protective circuit module. The electrode assembly may include a negative electrode plate and a positive electrode plate separated by a separator and rolled into a jellyroll configuration, the electrode terminal being connected to the negative electrode plate. The battery pack may also include an electrical insulator arranged on the cap plate in a vicinity of the electrode terminal, the electrical insulator to insulate the electrode terminal from the cap plate. One of the first pair of sides of the top case may include a recessed interference preventing portion at a location that corresponds to the electrical insulator. 
         [0012]    The recessed interference preventing portions of each side of the first pair of sides of the top case may include a first portion, a second portion and a third portion, the third portion may be further recessed along the edges of each of the first pair of sides than the second portion and the second portion may be further recessed along the edges of each of the first pair of sides than the first portion by having the third portion being nested within the second portion and the second portion being nested within the first portion. The third portion of the recessed interference preventing portion on one of the first pair of sides of the top case may correspond to a location of the electrode terminal. The third portion of the recessed interference preventing portion of one of the first pair of sides of the top case may correspond to the location of the weld. The second portion of the recessed interference preventing portion of one of the sides of the first pair of sides of the top case may correspond to a location of an electrical insulator on the top case that electrically insulates the electrode terminal from the cap plate. 
         [0013]    The top case may also include a position determination portion comprising a hook protruding from an inner wall of each of the first pair of sides. The protection circuit board may be arranged on an upper portion of the position determination portions. A location of the position determination portion on the inner wall of one of the first pair of sides may correspond to a location of the position determination portion on the inner wall of an other of the first pair of sides. Each inner wall of the first pair of sides of the top case may include a plurality of position determination portions. 
         [0014]    According to another aspect of the present invention, there is provided a battery pack that includes a battery cell including an electrode assembly arranged within a can and a cap plate sealing an opening of the can, the battery cell further including an electrode terminal arranged on the cap plate and electrically connected to the electrode assembly, a top case attached to the battery cell at a top portion of the battery cell, the top case having an inner space, the top case includes a top portion opposite from the electrode assembly and first and second pairs of opposed sides, the first pair of opposed sides having an edge, wherein a portion of the edge has a recessed interference preventing portion, a protective circuit module including a protection circuit board arranged within said inner space of said top case and electrically connected to the electrode assembly and an electrode tap electrically connecting the electrode terminal to the protection circuit board, the electrode tap having a first end, a second end opposite the first end and a bend portion arranged between the first end and the second end, the recessed interference preventing portion of the top case being arranged at a location that corresponds to the second end of the electrode tap. 
         [0015]    The bend portion may include a notch to facilitate bending of the bend portion. The first end of the electrode tap may be attached to the protection circuit board and the second end being attached to the electrode terminal. The electrode tap may be arranged between the cap plate and the protection circuit board arranged within the top case. The electrode tap may allow the top case to rotate open and closed with respect to the cap plate of the battery cell while electrically connecting the electrode assembly to the protection circuit board arranged within the top case 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    A more complete appreciation of then invention, and many of the attendant advantages to thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
           [0017]      FIG. 1  is an exploded perspective view illustrating a battery pack according to an embodiment of the present invention; 
           [0018]      FIG. 2  is a perspective view of a battery cell and a top case accommodating a protection circuit module (PCM) of  FIG. 1 ; 
           [0019]      FIG. 3  is a plan view of  FIG. 2 ; 
           [0020]      FIG. 4  is a cross-sectional view of the top case taken along line IV-IV of  FIG. 1 ; 
           [0021]      FIG. 5  is a perspective view of the battery pack of  FIG. 1 ; 
           [0022]      FIG. 6  is a close-up side view of top case taken along VI-VI of  FIG. 1 ; 
           [0023]      FIG. 7  is a close-up side view of top case taken along VII-VII of  FIG. 1 ; and 
           [0024]      FIG. 8  is a close-up view of an electrode tap of the battery pack of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawing. 
         [0026]    Turning now to  FIG. 1 ,  FIG. 1  is an exploded perspective view illustrating a battery pack  100  according to an embodiment of the present invention. Referring to  FIG. 1 , the battery pack  100  includes a battery cell  110 , a protection circuit module (PCM)  130 , a top case  150 , a bottom case  170 , and an outer case  190 . The battery cell  110  includes an electrode assembly  111 , a can  112  for accommodating the electrode assembly  111 , and a cap plate  113  sealing an opening of the can  112 . The electrode assembly  111  includes a positive electrode plate  114 , a negative electrode plate  115 , and a separator  116  interposed between the positive electrode plate  114  and the negative electrode plate  115 . 
         [0027]    The positive electrode plate  114  includes a positive electrode current collector made out of a metal foil and a positive electrode active material layer coated on at least one surface of the positive electrode current collector. A positive electrode lead  117  is electrically connected to the positive electrode current collector of the positive electrode plate  114 . The positive electrode lead  117  extends toward the top of the can  112  and is electrically connected to the cap plate  113 . The positive electrode lead  117  may instead be directly connected to the can  112 . 
         [0028]    The negative electrode plate  115  includes a negative electrode current collector made out of metal foil and a negative electrode active material layer coated on at least one surface of the negative electrode current collector. A negative electrode lead  118  is electrically connected to the negative electrode current collector of the negative electrode plate  115 . The negative electrode lead  118  extends toward the top of the can  112 . The negative electrode lead  118  is electrically connected to a protection device such as a thermal fuse  120 . The thermal fuse  120  is electrically connected to a negative electrode terminal  119 . The thermal fuse  120  is surrounded by a polymer layer  121  to block a reaction with an electrolyte. A gasket  122  is disposed around the negative electrode terminal  119 . The negative electrode terminal  119  is insulated from the cap plate  113  by the gasket  122 . If there is no thermal fuse  120 , the negative electrode lead  118  may be directly connected to the negative electrode terminal  119 . 
         [0029]    The separator  116  may be a film made out of a porous insulating material, such as polyethylene, polypropylene, or any combination thereof. 
         [0030]    The electrode assembly  111  is formed by winding the positive electrode plate  114 , the negative electrode plate  115 , and the separator  116  interposed between the positive electrode plate  114  and the negative electrode plate  115  into a jelly-roll type configuration. The wound electrode assembly  111  is inserted into the can  112 . The can  112  is a square pillar having space for accommodating the electrode assembly  111 . The can  112  is made out of a conductive metal, such as aluminum (Al), iron (Fe), and an alloy of Al or Fe, and is fabricated by press molding, for example, by deep drawing. 
         [0031]    The opening of the can  112  is sealed by the cap plate  113 . The can  112  itself serves as a positive electrode terminal by being electrically connected to the positive electrode plate  114 , the positive electrode lead  117 , and the cap plate  113 . 
         [0032]    A PCM  130  is disposed between the battery cell  110  and the top case  150 . The PCM  130  includes a protection circuit board  131 . The protection circuit board  131  includes a printed circuit substrate on which at least one circuit pattern layer is stacked. 
         [0033]    A plurality of electric devices  132  and a plurality of electrode output terminals  133  are mounted on the protection circuit board  131 . The electric devices  132  include an integrated circuit (IC) chip, a field effect transistor (FET), a resistor, a capacitor, a positive temperature coefficient (PTC) element  134 , etc. The electrode output terminal  133  includes a positive output terminal P+, a negative output terminal P−, and a resistance output terminal CF. 
         [0034]    A positive electrode tap  160  that is electrically connected to the cap plate  113  of the battery cell  110  is electrically connected to a trace for the positive electrode on the protection circuit board  131 . A trace is a conductive pathway arranged on the protection circuit board  131 , and a trace of the positive electrode is a trace on the protection circuit board  131  that is connected to the positive electrode plate  114  of the electrode assembly  111 . Likewise, a negative electrode tap  140  that is electrically connected to the negative electrode terminal  119  of the battery cell  110  is electrically connected to a trace for the negative electrode on the protection circuit board  131 . Accordingly, the battery cell  110  is electrically connected to the PCM  130 . 
         [0035]    In this regard, the PTC element  134  is disposed on the trace of the negative electrode of the protection circuit board  131 . The PTC element  134  is a safety element including a polymer and conductive particles. The PTC element  134  forcibly blocks a conductive pathway of the negative electrode between the protection circuit board  131  and the negative electrode terminal  119  when the temperature thereof or the current flowing therein exceeds a certain level. One end (or first metal thin plate)  143  of the negative electrode tap  140  is connected to the PTC element  134 , and the other end (or second metal thin plate)  144  of the negative electrode tap  140  is connected to the negative electrode terminal  119 . 
         [0036]    Meanwhile, an insulating tape  135  may be attached to a portion of the cap plate  113  corresponding to the PTC element  134 . Since cap plate  113  is positively charged, insulating tape serves to electrically insulate negative electrode terminal  119  from cap plate  113 . 
         [0037]    The PCM  130  is accommodated within the top case  150 . The top case  150  including the PCM  130  is coupled to the upper end portion of the battery cell  110 . The top case  150  protects the PCM  130  against external impact and prevents the protection circuit board  131  from being circuit-shorted. The top case  150  may be made out of a polymer resin such as polycarbonate. The top case  150  has a plurality of electrode output terminal holes  151  through which the electrode output terminal  133  is exposed outside of the top case  150 . 
         [0038]    The bottom case  170  covers the lower end portion of the battery cell  110 . 
         [0039]    The battery cell  110  is surrounded by the outer case  190 . The outer case  190  may be a pouch to which an adhesive and a label  191  are adhered. 
         [0040]    A method of fabricating the battery pack  100  will now be described. The electrode assembly  111  is fabricated by winding the positive electrode plate  114 , the negative electrode plate  115 , and the separator  116  interposed between the positive electrode plate  114  and the negative electrode plate  115  into a jelly-roll configuration. The wound electrode assembly  111  is inserted into the can  112 . The opening of the can  112  is sealed by the cap plate  113  by welding portions of cap plate  113  to can  112 . 
         [0041]    In this regard, the positive electrode lead  117  extending from the positive electrode plate  114  is welded to the bottom surface of cap plate  113 , and the negative electrode lead  118  extending from the negative electrode plate  115  is electrically connected to the thermal fuse  120  that is welded to the negative electrode terminal  119 . 
         [0042]    Separately, the PCM  130  is inserted into the top case  150  to prepare a sub-assembly. Then, the top case  150  is positioned at an upper portion of the battery cell  110 , and the negative electrode tap  140  is welded to the negative electrode terminal  119 . After the welding is completed, the top case  150  is coupled to the battery cell  110 . 
         [0043]    Then, the positive electrode tap  160  is electrically connected to the cap plate  113  by using a screw  153  via a screw hole  152  arranged in the top case  150 . The screw hole  152  is filled with an adhesive  154 . 
         [0044]    The bottom case  170  is coupled to the lower end portion of the battery cell  110  by an adhesive  171 . The outer surface of the battery cell  110  is surrounded by the outer case  190 . A label is  191  for allowing identification of information about the battery pack  100  is attached onto the outer surface of the outer case  190 . According to the assembly process, the battery pack  100  shown in  FIG. 5  is fabricated. 
         [0045]    In the present invention, the top case  150  has an interference preventing portion to avoid interference by a welding device when the negative electrode tap  140  is welded to the negative electrode terminal  119 . This will now be described in more detail below. 
         [0046]    Turning now to  FIGS. 2 and 3 ,  FIG. 2  is a perspective view of the battery cell  110  and the top case  150  accommodating the PCM  130  of  FIG. 1  and  FIG. 3  is a plan view of  FIG. 2 . Referring to  FIGS. 2 and 3 , the top case  150  includes a flat top portion  155 , a first long side  156  and a second long side  157  which extend downward from both long side edges of the top portion  155  and facing each other, and a first short side  158  and a second short side  159  which extend downward from both short side edges of the top portion  155  and facing each other. The top case  150  has space S for accommodating the PCM  130 . 
         [0047]    The PCM  130  includes the protection circuit board  131 . The negative electrode tap  140  and the positive electrode tap  160  are disposed on one surface of the protection circuit board  131  facing the battery cell  110 . 
         [0048]    The negative electrode tap  140  includes a first metal thin plate  143  and a second metal thin plate  144  that is bent with respect to the first metal thin plate  143 . The second metal thin plate  144  extends from and is integrally formed with the first metal thin plate  143 . 
         [0049]    The negative electrode tap  140  may have any shape provided the first metal thin plate  143  is electrically connected to the protection circuit board  131 , and the second metal thin plate  144  is electrically connected to the negative electrode terminal  119 . In addition, the first metal thin plate  143  and the second metal thin plate  144  may be integrally formed with each other or separately formed and then coupled to each other. 
         [0050]    In an assembly process of the PCM  130 , the first metal thin plate  143  is electrically connected to an element on the trace of the negative electrode of the protection circuit board  131 , such as the PTC element  134 . To achieve this, the first metal thin plate  143  may be soldered to PTC element  134 . This soldering process can occur when protection circuit module  130  is assembled to top case  150 . Meanwhile, the positive electrode tap  160  is electrically connected to an element on the trace of the positive electrode of the protection circuit board  131 . 
         [0051]    The top case  150  is positioned at an upper portion of the battery cell  110  when the negative electrode tap  140  is welded to the negative electrode terminal  119 . During this welding process, the top case  150  is positioned to expose a portion of the second metal thin plate  144  that is to be welded to the negative electrode terminal  119  in order to facilitate the welding. That is, the second long side  157  of the top case  150  is disposed close to one edge of the upper end portion of the battery cell  110 , and the first long side  156  facing the second long side  157  is disposed in a path of a welding rod  210  of the welding device that is applied in a direction perpendicular to the welding portion. Accordingly, the portion of the negative electrode terminal  119  that is to be welded to second metal thin plate  144  is exposed to the outside. 
         [0052]    The second metal thin plate  144  is in surface contact with the negative electrode terminal  119  and is welded to the negative electrode terminal  119  by the welding rod  210  of the welding device. The welding rod  210  passes the first long side  156  of top case  150  from an upper portion of the first long side  156  in a direction perpendicular to the portion of second metal thin plate  144  that is to be welded. 
         [0053]    In this regard, the top case  150  has a size suitable for being inserted onto the battery cell  110 , and thus the first long side  156  and the second long side  157  occupy more than a half of the upper portion of the top case  150 . Accordingly, when the welding rod  210  passes the first long side  156  to be positioned above the second metal thin plate  144 , the welding rod  210  may interfere with edge  156   a  of the first long side  156 . 
         [0054]    In order to prevent the interference, the first long side  156  has a first interference preventing portion  181 . The first interference preventing portion  181  is formed by partially cutting the first long side  156  along an edge  156   a  of the first long side  156  so that the first long side  156  becomes recessed in the vicinity of where the welding rod  210  passes. 
         [0055]    The size of the first interference preventing portion  181  cut from the first long side  156  is determined such that interference is not caused between the welding rod  210  and the first long side  156  when the welding rod  210  passes the first long side  156 . Furthermore, the first interference preventing portion  181  preferably has a size suitable to completely expose the portion of the second thin metal plate  144  that is to be welded to the negative electrode terminal  119  in a direction perpendicular to the welding portion. 
         [0056]    In addition, the second long side  157  has a second interference preventing portion  182 . The second interference preventing portion  182  is formed by partially cutting the second long side  157  to prevent interference between the second long side  157  and the negative electrode terminal  119  or the gasket  122  when the top case  150  is positioned at an upper portion of the battery cell  110 . 
         [0057]    The second interference preventing portion  182  includes a first portion  183  that is cut from one edge  157   a  of the second long side  157  and a second portion  184  that extends from the first portion  183  and is cut. The first portion  183  is cut to avoid interference with the insulating tape  135 , and the second portion  184  is cut to avoid interference with the negative electrode terminal  119  or the gasket  122 . The shape of the second interference preventing portion  182  is substantially identical to that of the first interference preventing portion  181 . 
         [0058]    In an alternate variation to this embodiment, the edge of the insulating tape  135  may instead be cut to prevent interference with the second long side  157  without forming the first portion  183 . 
         [0059]    In the top case  150  having the structure described above, the second metal thin plate  144  contacts the negative electrode terminal  119 , and the second long side  157  is positioned along one edge of the upper end portion of the battery cell  110 . In this arrangement, since the second long side  157  has the second interference preventing portion  182 , the second long side  157  may be positioned without interfering with the negative electrode terminal  119 , the gasket  122 , and the insulating tape  135  disposed on the cap plate  113 . 
         [0060]    Then, the welding rod  210  passes the first long side  156  from an upper portion of the first long side  156  in a direction perpendicular to the cap plate  113  so that the welding rod is positioned above the second metal thin plate  144 , and the welding process is performed. In this regard, since the first long side  156  of top case  150  has the first interference preventing portion  181 , the welding rod  210  may perform the welding without interfering with the first long side  156 . Thus, a welding points  300  are formed at a desired location on the second metal thin plate  144 . 
         [0061]    According to the process described above, the negative electrode tap  140  is welded to the negative electrode terminal  119 . After the welding is completed, the position of the top case  150  is changed according to the arrow in  FIG. 2  to assemble the top case  150  to the battery cell  110 . 
         [0062]    Meanwhile, the position of the PCM  130  to which the negative electrode tap  140  is electrically connected may be determined by a position determination portion when the PCM  130  is inserted into an inner space S of the top case  150 . 
         [0063]    Turning now to  FIGS. 6 and 7 ,  FIG. 6  is a close-up view of first long side  156  of top case  150  taken along line VI-VI of  FIG. 1  and  FIG. 7  is a close-up view of second long side  157  of top case  150  taken along line VII-VII of  FIG. 1 . Referring now to  FIG. 6 , edge  156   a  of first long side  156  is actually recessed in three nested steps. Portions  181   z  at either end of edge  156   a  are unrecessed, and first interference preventing portion  181  at a center of edge  156   a  is nested within recessed portions  181   x , which are nested within recessed portions  181   y , which are recessed with respect to unrecessed portions  181   z . Referring now to  FIG. 7 , edge  157   a  of second long side  157  has a profile similar to that of edge  156   a  of  FIG. 6 , where portion  184  is recessed from portions  183  and  182   x , which are recessed from portions  182   y  which are recessed from unrecessed portions  182   z  at the left and right sides of edge  157   a.    
         [0064]    Referring now to  FIG. 8 ,  FIG. 8  is a close-up view of the negative electrode tap  140  illustrated in  FIGS. 1 through 3 . As can be seen in  FIG. 8 , negative electrode tap  140  has a first end or first metal thin plate  143  connected to second end or second metal thin plate  144  by a bend portion  145 . The bend portion  145  is capable of being bent, and may include one or more notches  146  to facilitate in the bending process. 
         [0065]    In the present invention, the second end  144  of negative electrode tap is welded to negative electrode terminal  119 , and the first end  143  is attached to protective circuit board  131  which is fixed within inner space S of top case  150 . More specifically, the first end  143  may be connected to PTC element  134  arranged on a bottom side of protective circuit board  131 . 
         [0066]    Bend portion  145  having notches  146  is of significance during assembly as after both first and second ends  143  and  144  are fixed to the protective circuit board  131  and negative electrode terminal  119  respectively, top case  150  containing the protective circuit board  131  within is moved with respect to the battery cell  110  and the bend portion  145  with notches  146  allows the top case  150  to move without breaking negative electrode tap  140  even though the first end  143  of negative electrode tap  140  is attached to the protective circuit board  131  arranged within top case  150 . 
         [0067]    Turning now to  FIG. 4 ,  FIG. 4  is a cross-sectional view taken along line IV-IV of  FIG. 1 . Referring to  FIG. 4 , a first position determination portion  401  is disposed on an inner wall of the first long side  156 . The first position determination portion  401  may be a hook protruding from the inner wall of the first long side  156  to the inner space S of the top case  150 . A second position determination portion  402  is formed on an inner wall of the second long side  157 . The second position determination portion  402  may also be a hook protruding from the inner wall of the second long side  157  to the inner space S of the top case  150 . The first position determination portion  401  and the second position determination portion  402  are formed at the same location along the inner walls of the top case  150 . A plurality of the first position determination portions  401  and the second position determination portions  402  may be formed. 
         [0068]    In an alternate variation to the embodiment, the first position determination portion  401  and the second position determination portion  402  may have a shape consecutively protruding along the circumference of the inner wall of the top case  150 . In addition, the top case  150  may have a coupling groove and a projection at a location corresponding to the protection circuit board  131  which are coupled to each other. The position of the PCM  130  is not limited in the top case  150 . 
         [0069]    The protection circuit board  131  having the structure described above is inserted into the space S of the top case  150 , and the edge of the protection circuit board  131  is guided from a lower portion  403  of the first position determination portion  401  and a lower portion  404  of the second position determination portion  402 . The protection circuit board  131  that passes the lower portion  403  of the first position determination portion  401  and the lower portion  404  of the second position determination portion  402  is positioned at an upper portion  405  of the first position determination portion  401  and an upper portion  406  of the second position determination portion  402  which serve as a hook. Accordingly, the PCM  130  may be installed in the top case  150 . 
         [0070]    As described above, in the battery pack, interference preventing portions are formed in the top case, and thus interference does not occur when the electrode tap is welded to the electrode terminal. In addition, since the top case has the position determination portions, the electrode tap may be efficiently welded to the electrode terminal in the top case after the PCM has been assembled into the top case. 
         [0071]    It should be understood that the exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.