Patent Publication Number: US-2013252071-A1

Title: Battery

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-066061, filed Mar. 22, 2012, the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a battery. 
     BACKGROUND 
     Secondary batteries are widely used as power sources for electric vehicles, hybrid electric vehicles, and electric bicycles or for electronic apparatuses. For example, lithium-ion secondary batteries, non-aqueous secondary batteries, have become noticeable as power sources for electric vehicles and the like, since they have high output power and high energy density. 
     In general, a secondary battery is constructed as a cell comprising an outer casing of aluminum or the like, an electrode group, and electrode terminals. The outer casing is in the form of a flat rectangular box. The electrode group is accommodated together with an electrolyte in the outer casing. The electrode terminals are disposed on the outer casing and connected to the electrode group. 
     Further, the capacity and output power are increased by using an assembled battery or secondary battery device (or battery) comprising the assembled battery and an electric circuit attached thereto. The assembled battery comprises a plurality of cells arranged side by side in a case and connected in parallel or series. 
     In batteries, case-side terminals are expected to be precisely connected to leads on electrode bodies. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing an external appearance of a secondary battery device according to an embodiment; 
         FIG. 2  is an exploded perspective view showing the structure of the secondary battery device; 
         FIG. 3  is a sectional view showing the structure of terminal areas of the secondary battery device; 
         FIG. 4  is an explanatory diagram showing an assembly process for the secondary battery device; 
         FIG. 5  is an explanatory diagram showing the assembly process for the secondary battery device; 
         FIG. 6  is an explanatory diagram showing the structure of a secondary battery device according to another embodiment and an assembly process therefor; 
         FIG. 7  is an explanatory diagram showing the structure of the secondary battery device and the assembly process therefor; 
         FIG. 8  is a sectional view showing the structure of terminal areas of the secondary battery device; 
         FIG. 9  is an explanatory diagram showing an assembly process for a secondary battery device according to still another embodiment; 
         FIG. 10  is an explanatory diagram showing a welding process for the secondary battery device; 
         FIG. 11  is an explanatory diagram showing a sealing process for the secondary battery device; and 
         FIG. 12  is a plan view showing the structure of a terminal of the secondary battery device. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a battery comprises, an electrode body comprising a positive electrode plate, a negative electrode plate, and an insulating separator disposed between the positive and negative electrode plates, a lead electrically connected to the electrode body, and a metal terminal comprising a cavity electrically connected to the lead at any one point. 
     First Embodiment 
     A secondary battery device  1  according to a first embodiment will now be described with reference to  FIGS. 1 to 5 . In these drawings, arrows X, Y and Z indicate three orthogonal directions, individually, and some structural elements are enlarged or reduced in scale or omitted for ease of illustration. 
       FIG. 1  is a perspective view showing an external appearance of the secondary battery device (battery) according to the embodiment.  FIG. 2  is an exploded perspective view.  FIG. 3  is a sectional view of terminal areas taken along line A-A of  FIG. 1 ;  FIG. 4  is a sectional view taken along line B-B of  FIG. 1 , showing the internal structure and an assembly process; and  FIG. 5  is a sectional view taken along line A-A of  FIG. 1 . 
     As shown in  FIGS. 1 and 2 , the secondary battery device  1  comprises a battery case  11 , in which a plurality of divided spaces are formed, and a plurality of electrode groups  12  accommodated together with a non-aqueous electrolyte in the case  11 . The secondary battery device  1  is constructed as an assembled battery which comprises a plurality of secondary battery units serving as secondary battery. In the present embodiment, each of the electrode groups  12  comprises an electrode body and leads (for example, positive electrode lead  22   a  and negative electrode lead  22   b  shown in  FIG. 2 ). The electrode body comprises a positive electrode plate and negative electrode plate, with an insulating separator therebetween. The leads are electrically connected individually to the positive and negative electrode plates of the electrode body. 
     The battery case  11  is in the form of a rectangular box, comprising first and second case members  13  and  14  on the upper and lower sides, respectively. The first and second case members  13  and  14  are assembled and sealed together to form a closed space in the battery case  11  that accommodates the electrode groups  12  together with the non-aqueous electrolyte. 
     Preferably, a thermoplastic (or amorphous) resin is used for the first and second case members  13  and  14 . For example, the resin material may be modified polyphenylene ether [m-PPE]), which is an insulating synthetic resin. 
     The first case member  13  comprises a rectangular plate-like lid  13   a , which is a resin molding constituting a ceiling wall that closes a top opening of the second case member  14 . The first case member  13  has the functions of sealing accommodation sections  11   a  in the battery case  11  in a liquid-tight manner and preventing a short circuit through electrical insulation. 
     The first case member  13  comprises the lid  13   a  and a plurality of terminals  15  formed thereon by insert molding. In this case, the integrally molded terminals  15  correspond in number to the positive and negative electrode leads  22   a  and  22   b  of the accommodated electrode groups  12 . 
     The terminals  15  serve to position the first case member  13  on the second case member  14  and assemble them together and are arranged on their corresponding positive and negative electrode leads  22   a  and  22   b  of the electrode groups  12 . 
     As shown in  FIG. 3 , the terminals  15  are made of metal, such as aluminum. Each terminal  15  is, for example, circular in a plan view and integrally comprises a cylindrical side portion  15   a  and circular bottom portion  15   b . It is recessed inward to form a hollow circular cavity  15   c  at the junction to the positive and negative electrode leads  22   a  and  22   b.    
     The outer peripheral surface of the side portion  15   a  of the terminal  15  is formed integrally with the plastic first case member  13  by insert molding such that it is bonded and held. The bottom portion  15   b  is a thin-walled portion whose mediolateral thickness (in the direction of arrow Z) is smaller than that of the side portion  15   a . The bottom portion  15   b  can be subjected to welding, such as laser welding, through the cavity  15   c  from the outer surface. 
     The laser welding should preferably be performed in a circular manner, so that the bottom portion  15   b  should preferably have a circular shape. Weld beads formed by laser welding are not limited to a circular shape and may have various other shapes, such as elliptical or polygonal shapes. 
     For example, plate thickness t 1  of the lid  13   a  of the first case member  13  is set to about 4 mm; Z-direction thickness t 2  of the side portion  15   a  of the terminal  15  to about 10 mm, inner diameter d 1  of the cavity  15   c  to about 7 mm, and Z-direction thickness t 3  of the bottom portion  15   b  to about 0.5 mm. 
     The terminal  15  penetrates the lid  13   a  of the first case member  13  so that its one Z-direction end projects to the outside of the first case member and is connected to a bus bar  18  and an external terminal and the other end projects inward and is connected to its corresponding electrode group  12 . 
     Further, electrolyte injection holes  16   a  are formed in transverse central portions of the first case member  13  such that they are closed by sealing members  16 , individually. Furthermore, a gas exhaust valve and the like are arranged on the first case member  13 . The gas exhaust valve comprises a thin-walled portion formed by substantially halving the thickness of a part of the lid. If gas continues to be produced in the case in an abnormal mode such that the internal pressure is increased to a predetermined value or more, the gas exhaust valve is opened so that the internal pressure is reduced to prevent a failure, such as a rupture. 
     As shown in  FIGS. 1 ,  2  and  4 , the second case member  14  is a resin molding comprising an outer shell  14   a , partition plates  14   b , supporting portions  14   c , and ribs  14   d , which are integrally constructed by injection molding or the like. The outer shell  14   a  is in the form of an open-topped rectangular box. The partition plates  14   b  are arranged side by side in a first direction (X-direction in the drawings) in the outer shell  14   a . The supporting portions  14   c  are arranged on top opening edges of the outer shell  14   a . The ribs  14   d  serve to reinforce the supporting portions  14   c.    
     The outer shell  14   a  is a box comprising the accommodation sections  11   a  arranged along the electrode groups  12  and opens on one end side (at the upper part in the drawings). 
     The partition plates  14   b  are arranged side by side so that they divide the internal space of the outer shell  14   a  into a plurality of parts in the Y-direction, thereby forming the accommodation sections  11   a  as many as the electrode groups  12  in parallel relation. In this case, 11 partition plates  14   b  on ZY-planes are arranged side by side in the X-direction. The partition plates  14   b  have the functions of positioning the electrode groups  12  and preventing a short circuit between the electrode groups  12  or members. The partition plates  14   b  define inside the outer shell  14   a  the accommodation sections  11   a , which are divided from one another and open at one end. Each accommodation section  11   a  has an elongated rectangular shape corresponding to each electrode group  12  such that the electrode group  12  can be accommodated extending in the transverse direction (Y-direction) of the battery case  11 . 
     The supporting portions  14   c  are plates that are individually arranged at transversely opposite ends of the opening edges of the outer shell  14   a  and project outward. The supporting portions  14   c  are arranged throughout the X-direction length of the opening edges on the opposite sides in the Y-direction, and are configured to individually support the positive and negative electrode leads  22   a  and  22   b . The electrode leads  22   a  and  22   b  placed on the supporting portions  14   c  are sandwiched between the lid  13   a  and supporting portions  14   c  with the electrode groups  12  located in the accommodation sections  11   a . The ribs  14   d  are triangular plates that connect the outer surface of the outer shell  14   a  and the lower surfaces of the supporting portions  14   c , thereby reinforcing the supporting portions  14   c.    
     Each electrode group  12  comprises a coil  21 (electrode body) and the positive and negative electrode leads  22   a  and  22   b  that are led out on the opposite sides of the coil  21  and connected to current collectors  22  at the opposite ends. 
     The coil  21  is formed into a flat rectangular shape in such a manner that, for example, the positive and negative electrode plates are spirally wound with the insulating separator (not particularly shown) between them and further radially compressed. In this case, for example, lithium cobalt oxide and lithium titanate are used as the positive and negative electrode materials, respectively, of the coil  21 . 
     The positive and negative electrode leads  22   a  and  22   b  are connected to the positive and negative electrode plates, respectively, of the coil  21  and disposed integrally with the current collectors  22  led out at the opposite ends of the coil  21 , and they are made of metal, such as aluminum or copper. The positive and negative electrode leads  22   a  and  22   b  are plates that extend above the coil  21  and are bent so as to project transversely outward relative to the battery case  11  from the coil  21 . The bottom portions  15   b  of the terminals  15  are connected individually to the positive and negative electrode leads  22   a  and  22   b  from above. 
     The positive and negative electrode leads  22   a  and  22   b  outwardly project to be sandwiched between the supporting portions  14   c  and lid  13   a  and connected to the bottom portions  15   b  with the coils  21  located individually in the accommodation sections  11   a  in the battery case  11 . 
     The electrode groups  12  are oriented so that the positive and negative electrode leads  22   a  and  22   b  of each two adjacent electrode groups  12  are arranged alternately. The electrode groups  12  are electrically connected, for example, in series by a plurality of bus bars  18  for use as electrically conductive members through the terminals  15 . In this embodiment, 11 bus bars  18  are located in predetermined positions and formed integrally with the first case member  13  so that the adjacent electrodes of 12 electrode groups  12  are connected in series. 
     Each bus bar  18  is a metal plate member of an electrically conductive material, such as aluminum, copper, or bronze, and integrally comprises a pair of terminal areas  18   a  and  18   b . The one terminal area  18   a  of the bus bar  18  is electrically connected to the positive electrode lead  22   a  of each electrode group  12 , and the other terminal area  18   b  to the negative electrode lead  22   b  of an adjoining electrode group  12 . Also, these terminal areas  18   a  and  18   b  are electrically connected to each other. The 12 electrode groups  12  are connected in series by the bus bars  18 . Alternatively, the electrode groups  12  may be connected in parallel. 
     The terminals  15  are connected to the negative electrode lead  22   b  of that one of the electrode groups  12  which is located at one end of the array and the positive electrode lead  22   a  of the electrode group  12  at the other end, and function as external output terminals. 
     Further, the bus bars  18  and a battery monitoring board (not shown), comprising a voltage control unit, voltage detector, temperature sensor, etc., are installed outside the first case member  13 . Also, a lid (not shown) that covers the bus bars  18  and battery monitoring board is attached to the outside of the first case member  13 . 
     A manufacturing method for the secondary battery device according to the present embodiment will now be described with reference to  FIGS. 4 and 5 . In an assembly process, as shown in  FIGS. 4 and 5 , the electrode groups  12  are first introduced individually into accommodation chambers of the second case member  14  on the lower side through the top opening, whereby they are assembled to the second case member  14 . Thereupon, the positive and negative electrode leads  22   a  and  22   b  are located and supported on the supporting portions  14   c  on the opposite sides of the second case member  14 . 
     When this is done, the positive and negative electrode leads  22   a  and  22   b  are connected individually to the terminals  15  that are disposed integrally with the second case member  14 , whereupon the electrical connection and bonding/holding of the terminal areas are simultaneously performed, as shown in  FIG. 3  and &lt;b&gt; of  FIG. 5 . 
     Then, a welding process, such as laser welding, is performed such that each terminal  15  and the positive and negative electrode leads  22   a  and  22   b  are bonded together. In doing this, as shown in  FIG. 3 , welding to the thin-walled bottom portion  15   b  can be performed through the cavity  15   c  from outside the case  11 , so that the welding process can be easily accomplished with reliability. The battery manufactured by this welding process is formed with a welding trace on the outer surface (upper surface in the drawings) of the bottom portion  15   b . In this case, for example, the welding trace is formed along a circular welding path on the outer surface of the bottom portion  15   b . Since junctions between the terminal  15  and positive and negative electrode leads  22   a  and  22   b  are supported from below by the supporting portion  14   c  in positions deviated outward from the coil  21 , moreover, the welding process can be stably performed, and an influence of laser radiation or the like on the coil  21  during the welding process can be avoided. 
     Subsequently, the opening edges of the first and second case members  13  and  14  are bonded and sealed together by thermal deposition or the like. 
     Thereafter, various processes, such as injection of the electrolyte, initial charge/discharge, etc., are sequentially performed, and finally, the terminals  15  outwardly projecting from the case  11  are connected in series by the bus bars  18 . Thereupon, the secondary battery device  1  for use as an assembled battery is completed. 
     The secondary battery device and the manufacturing method therefor according to the present embodiment can provide the following effects. Specifically, the metal terminals  15  are disposed integrally on the plastic first case member  13 , and the cavities  15   c  are arranged in positions corresponding to the leads. Thus, the process for assembling the battery case  11  and the connection of the terminal areas can be simultaneously performed, and the welding or other bonding process can be performed from outside the battery case  11 . Further, the cavity  15   c  can be thin-walled so that the outer peripheral surface of the side portion  15   a  is wide. In this way, the cavity  15   c  can be easily externally bonded to the positive and negative electrode leads  22   a  and  22   b  while maintaining the bondability with the plastic case member  13  during the insert molding. 
     Since the case  11  integrally comprises the terminals  15 , moreover, the electrode groups  12  can be arranged directly in the accommodation sections  11   a  in the case  11  so that their positive and negative electrode leads  22   a  and  22   b  are electrically connected to the terminals  15  as the case  11  is assembled. Thus, the assembly parts count can be reduced, and the assembly process can be simplified while maintaining high precision. 
     Further, the junctions between each terminal  15  and the positive and negative electrode leads  22   a  and  22   b  project on the opposite sides and are supported from below by the supporting portion  14   c  in positions deviated outward from the coil  21 . Therefore, the welding process can be stably performed, and an influence of laser radiation or the like on the coil  21  during the welding process can be avoided. 
     Second Embodiment 
     The structure of and a manufacturing method for a secondary battery device  2  according to a second embodiment will now be described with reference to  FIGS. 5 to 8 . In these drawings, arrows X, Y and Z indicate three orthogonal directions, individually, and some structural elements are enlarged or reduced in scale or omitted for ease of illustration. 
     In the present embodiment, each of terminals  15  comprises, in place of the thin-walled cavity  15   c , a hole portion  115   c  that penetrates it in a mediolateral direction (indicated by arrow Z). In this arrangement, positive and negative electrode leads  22   a  and  22   b  are bent transversely inward, and a connector  23  is formed on each of the leads  22   a  and  22   b  such that it is inserted into the hole portion  115   c  for connection. In the present embodiment, moreover, a first case member  13  comprises partition plates  113   b  that define accommodation sections  11   a , which are closed by a second case member  14 . Since other structures are the same as those of the first embodiment, a repeated description thereof is omitted. 
       FIGS. 6 and 7  are explanatory diagrams showing the sectional configuration of the secondary battery device  2  and an assembly process, and  FIG. 8  is an enlarged view showing terminal areas. 
     As shown in &lt;b&gt; of  FIGS. 6 and 7 , the secondary battery device  2 , like the secondary battery device  1  of the first embodiment, comprises a battery case  11 , in which a plurality of divided spaces are formed, and a plurality of electrode groups  12  accommodated together with a non-aqueous electrolyte in the battery case  11 . Each of the electrode groups  12  is constructed as an assembled battery, which integrally comprises a plurality of secondary battery units serving as secondary batteries. 
     In the present embodiment, as in the foregoing first embodiment, each of the electrode groups  12  comprises an electrode body and leads (for example, positive electrode lead  22   a  and negative electrode lead  22   b  shown in  FIG. 2  and &lt;a&gt; and &lt;b&gt; of  FIG. 6 ). The electrode body comprises a positive electrode plate, negative electrode plate, and insulating separator between them. The leads are electrically connected individually to the positive and negative electrode plates of the electrode body. The battery case  11  is in the form of a rectangular box, comprising first and second case members  13  and  14  on the upper and lower sides, respectively. The first and second case members  13  and  14  are assembled and sealed together to form a closed space in the case  11  that accommodates the electrode groups  12  together with the non-aqueous electrolyte. 
     Preferably, a thermoplastic (or amorphous) resin is used for the first and second case members  13  and  14 . For example, the resin material may be modified polyphenylene ether [m-PPE]), which is an insulating synthetic resin. 
     The first case member  13  comprises an outer shell  113   a  and the partition plates  113   b , which are integrally constructed by injection molding or the like. The outer shell  113   a  is in the form of an open-bottomed rectangular box. The partition plates  113   b  are arranged side by side in a first direction (X-direction in the drawings) in the outer shell  113   a . The outer shell  113   a  is shaped along the electrode groups  12  and opens on the other end side (at the lower part in the drawings). 
     The partition plates  113   b  are arranged side by side so that they divide the internal space of the outer shell  113   a  into a plurality of parts in the Y-direction, thereby forming the accommodation sections  11   a  as many as the electrode groups  12  in parallel relation. In this case, 11 partition plates  113   b  on ZY-planes are arranged side by side in the X-direction. The partition plates  113   b  have the functions of positioning the electrode groups  12  and preventing a short circuit between the electrode groups  12  or members. The partition plates  113   b  define inside the outer shell  113   a  the accommodation sections  11   a , which are divided from one another and open downward. Each accommodation section  11   a  has an elongated rectangular shape corresponding to each electrode group  12  such that the electrode group  12  can be accommodated extending in the transverse direction (Y-direction) of the battery case  11 . 
     A bottom portion  113   c  of the outer shell  113   a  integrally comprises the terminals  15  formed by insert molding. In this case, the integrally molded terminals  15  correspond in number to the positive and negative electrode leads  22   a  and  22   b  of the accommodated electrode groups  12 . 
     The terminals  15  are arranged so that the connectors  23  on the positive and negative electrode leads  22   a  and  22   b  of the electrode groups  12  are inserted individually into their respective hole portions  115   c  the moment the electrode groups  12  are positioned and assembled to the first case member  13 . The terminals  15  are made of metal, such as aluminum or copper. Each terminal  15  is, for example, circular in a plan view and comprises a cylindrical side portion  115   a . It is formed with the hole portion  115   c  that penetrates it in the mediolateral direction at the junction between the positive and negative electrode leads  22   a  and  22   b . The outer peripheral surface of the side portion  115   a  of the terminal  15  is formed integrally with the plastic first case member  13  by insert molding. The terminal  15  penetrates the bottom portion  113   c  of the first case member  13  so that its one Z-direction end projects to the outside of the first case member and is connected to a bus bar  18  and an external terminal. 
     As shown in  FIG. 8 , each electrode group  12  comprises a coil  21  and the positive and negative electrode leads  22   a  and  22   b  that are led out on the opposite sides of the coil  21 . The coil  21 , like that of the first embodiment, is formed into a flat rectangular shape in such a manner that, for example, the positive and negative electrode plates are spirally wound with the insulating separator (not particularly shown) between them and further radially compressed. In this case, for example, lithium cobalt oxide and lithium titanate are used as the positive and negative electrode materials, respectively, of the coil  21 . 
     The positive and negative electrode leads  22   a  and  22   b  are connected to the positive and negative electrode plates, respectively, of the coil  21  and disposed integrally with current collectors  22  led out at the opposite ends of the coil  21 , and they are made of metal, such as aluminum or copper. The positive and negative electrode leads  22   a  and  22   b  are plates that extend above the coil  21  and are bent so as to project transversely inward relative to the battery case  11  above the coil  21 . The columnar connectors  23  individually protrude upward from the electrode leads  22   a  and  22   b  toward the first case member  13 . 
     In the present embodiment, the connectors  23  are inserted into their corresponding hole portions  115   c  and bonded to their inner surfaces, whereupon they are electrically connected to the terminals  15  and positive and negative electrode leads  22   a  and  22   b.    
     The second case member  14  comprises a rectangular plate-like lid  114   a , which closes a bottom opening of the first case member  13 , and seals the accommodation sections  11   a  in the battery case  11  in a liquid-tight manner. 
     The electrode groups  12  of the secondary battery device  2 , like those of the secondary battery device  1  of the first embodiment, are oriented so that the positive and negative electrode leads  22   a  and  22   b  of each two adjacent electrode groups  12  are arranged alternately. The electrode groups  12  are electrically connected, for example, in series by a plurality of bus bars  18  for use as electrically conductive members through the terminals  15 . 
     A manufacturing method for the secondary battery device according to the present embodiment will now be described with reference to  FIGS. 6 and 7 . In an assembly process, as shown in  FIGS. 6 and 7 , the electrode groups  12  are first introduced individually into the accommodation sections  11   a  in the first case member  13  on the upper side through the bottom opening, whereby they are assembled to the first case member  13 . Thereupon, the upwardly projecting connectors  23  are inserted into their corresponding hole portions  115   c  of the terminals  15  that are disposed integrally with the first case member  13 , above the positive and negative electrode leads  22   a  and  22   b , individually. Thus, electrical connection and bonding of the terminals  15  and leads  22   a  and  22   b  are simultaneously performed. 
     Then, a welding process, such as laser welding, is performed such that each terminal  15  and the positive and negative electrode leads  22   a  and  22   b  are bonded together. 
     In doing this, welding to the bonded regions can be performed through the hole portion  115   c  from outside the case  11 , so that the welding process can be easily accomplished with reliability. The battery manufactured by this welding process is formed with a welding trace on an outer surface (upper surface in the drawings) around the hole portion  115   c.    
     Subsequently, the second case member  14  is assembled to the first case member  13  so as to close its bottom opening, and their opening edges are bonded and sealed together by thermal deposition or the like. As in the case of the first embodiment, moreover, various processes, such as injection of the electrolyte, initial charge/discharge, etc., are sequentially performed, and finally, the terminals  15  outwardly projecting from the case  11  are connected in series by the bus bars  18 . Thereupon, the secondary battery device  2  for use as an assembled battery is completed. 
     The secondary battery device  2  and the manufacturing method therefor according to the present embodiment can provide the same effects as in the first embodiment. Specifically, the metal terminals  15  are disposed integrally on the plastic first case member  13 , and the hole portions  115   c  are arranged in positions corresponding to the respective connectors  23  of the positive and negative electrode leads  22   a  and  22   b . Thus, the process for assembling the battery case  11  and the connection of the terminal areas can be simultaneously performed, and the welding process can be performed from outside the case  11 . Since the case  11  integrally comprises the terminals  15 , moreover, the electrode groups  12  can be arranged directly in the accommodation sections  11   a  in the case  11  so that their positive and negative electrode leads  22   a  and  22   b  are electrically connected to the terminals  15  as the case  11  is assembled. Thus, the assembly parts count can be reduced, and the assembly process can be simplified while maintaining high precision. 
     Further, positioning can be facilitated and reliable bonding can be achieved by inserting the projecting connectors  23  into the hole portions  115   c.    
     Third Embodiment 
     The structure of and a manufacturing method for a secondary battery device  3  according to a third embodiment will now be described with reference to  FIGS. 9 to 12 . In these drawings, arrows X, Y and Z indicate three orthogonal directions, individually, and some structural elements are enlarged or reduced in scale or omitted for ease of illustration. 
     In the present embodiment, each of terminals  15  comprises, in place of the thin-walled cavity  15   c , a hole portion  115   c  that penetrates it in a mediolateral direction, and the respective upper surfaces of plate-like positive and negative electrode leads  22   a  and  22   b  are resistance-welded. Since other structures are the same as those of the first embodiment, a repeated description thereof is omitted. 
     In the present embodiment, as shown in  FIGS. 9 to 11 , the terminals  15  are made of metal, such as aluminum or copper. Each terminal  15  is, for example, circular in a plan view and comprises a cylindrical side portion  115   a . It is formed with the hole portion  115   c  that penetrates it in the mediolateral direction at the junction between the positive and negative electrode leads  22   a  and  22   b . The outer peripheral surface of the side portion  115   a  of the terminal  15  is formed integrally with a plastic first case member  13  by insert molding. The terminal  15  penetrates a lid  13   a  of the first case member  13  so that its one Z-direction end projects to the outside of the first case member and is connected to a bus bar  18  and an external terminal. 
     Further, projections  115   d  for spot welding protrude inward (downward in the drawings) from the inner end surface of each terminal  15 . As shown in  FIG. 12 , the projections  115   d  are arranged individually at three spots equally spaced at 120° on, for example, a cylindrical side peripheral portion. 
     The manufacturing method for the secondary battery device according to the third embodiment will now be described with reference to  FIGS. 9 to 11 . Since processes other than a welding process are the same as those of the first embodiment, a description thereof is omitted. 
     When electrode groups  12  are assembled to the first case member  13  in an assembly process, as shown in  FIG. 9 , the projections  115   d  abut the positive and negative electrode leads  22   a  and  22   b . If current is passed through an electrode  31  located in the hole portion  115   c  in this state, as shown in  FIG. 10 , the projections  115   d  are electrified and melted by resistance heat. Thereupon, the leads  22   a  and  22   b  and terminals  15  are spot-welded. Further, an electrically conductive sealant  32 , such as a low-melting metal, is filled into each hole portion  115   c  from outside a case  11  to achieve sealing and electrical connection, as shown in  FIG. 11 , whereupon the welding process is completed. 
     In the present embodiment, as in the foregoing first and second embodiments, each of the electrode groups  12  comprises an electrode body and leads (for example, positive and negative electrode leads  22   a  and  22   b  shown in  FIGS. 1 and 9 ). The electrode body comprises a positive electrode plate, negative electrode plate, and insulating separator between them. The leads are electrically connected individually to the positive and negative electrode plates of the electrode body. 
     In this arrangement, resistance welding, filling of the sealant  32 , etc., can be performed through the hole portion  115   c  from outside the case  11 , so that the welding process can be easily accomplished with reliability. In the battery manufactured by this welding process, the sealant  32  is filled into the hole portion  115   c . Subsequently, the opening edges of the first case member  13  and a second case member  14  are bonded and sealed together by thermal deposition or the like. 
     Thereafter, various processes, such as injection of the electrolyte, initial charge/discharge, etc., are sequentially performed, and finally, the terminals  15  outwardly projecting from the case  11  are connected in series by the bus bars  18 . Thereupon, the secondary battery device  3  for use as an assembled battery is completed. 
     The secondary battery device  3  and the manufacturing method therefor according to the present embodiment can provide the same effects as in the first and second embodiments. Specifically, the metal terminals  15  are disposed integrally on the plastic first case member  13 , and the terminals  15  are arranged in positions corresponding to the positive and negative electrode leads  22   a  and  22   b . Thus, the process for assembling the battery case  11  and the connection of the terminal areas can be simultaneously performed, and the welding process can be performed from outside the case  11 . Since the case  11  integrally comprises the terminals  15 , moreover, the electrode groups  12  can be arranged directly in accommodation sections  11   a  in the case  11  so that their positive and negative electrode leads  22   a  and  22   b  are electrically connected to the terminals  15  as the case  11  is assembled. Thus, the assembly parts count can be reduced, and the assembly process can be simplified while maintaining high precision. 
     The embodiments described herein are exemplary only and are not limiting the scope of the invention, and specific configurations, materials, assembly procedure, etc., may be changed as required. 
     For example, the resin material used for the first and second case members  13  and  14  may be any of various materials other than m-PPE described before. Available materials for this purpose include, for example, olefin resins, such as PE, PP, and PMP; polyester resins, such as PET, PBT, and PEN; POM resins; polyamide resins, such as PA6, PA66, and PA12; crystalline resins, such as PPS and LCP, and their alloy resins; and noncrystalline resins, such as PS, PC, PC/ABS, ABS, AS, PES, PEI, and PSF, and their alloy resins. A laminated film may be used for the second case member. Further, materials for the positive and negative electrodes of the coil  21  and the terminals  15  are not limited to the above-described ones, and may be appropriately changed. 
     In the procedures described in the first and third embodiments, the upper first case member  13  is assembled after the electrode groups  12  are arranged in the accommodation sections  11   a  previously formed in the lower second case member  14 . In the procedure described in the second embodiment, in contrast, the opening is closed by the second case member  14  after the electrode groups  12  are arranged in the accommodation sections  11   a  previously formed in the upper first case member  13 . Alternatively, however, the structures of the terminals  15  and battery case  11  and the procedures may be combined oppositely in each of the embodiments. 
     In the process for arranging the electrode groups  12  in the accommodation sections  11   a  in the case members  13  and  14 , the electrode groups  12  may be introduced one after another or collectively. 
     Although the electrode groups  12  are arranged, for example, side by side in a row in the first direction according to the embodiments described above, they may alternatively be arranged in a plurality of rows. In the above-described embodiments, moreover, the electrode groups  12  are connected in series to increase voltage. Alternatively, however, the electrode groups  12  may be arranged in parallel to increase the capacity, thereby forming an assembled battery. Furthermore, it is also applicable to a configuration in which a plurality of blocks each including some electrode groups  12  arranged in parallel are connected in series. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.