Abstract:
A rechargeable battery includes an electrode assembly including wound positive and negative electrodes with a separator therebetween, a case configured to contain the electrode assembly, a cap plate configured to seal an opening of the case, the cap plate including a terminal hole therethrough, an electrode terminal through the terminal hole of the cap plate, the electrode terminal including a terminal through-out portion extending through the terminal hole, a terminal plate connected to the terminal through-out portion outside the case, and a fastening portion including a terminal fastening portion connected to the terminal plate, and a lead tab inside the case, the lead tab connecting the terminal through-out portion of the electrode terminal to the electrode assembly.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    The described technology relates generally to a rechargeable battery with an improved fastening force of an electrode terminal. 
         [0003]    2. Description of the Related Art 
         [0004]    A rechargeable battery may include an electrode assembly formed in a jelly roll shape by winding a positive electrode, a negative electrode, and a separator therebetween, and a case containing the electrode assembly. The rechargeable battery may further include a cap plate sealing an opening of the case, an electrode terminal electrically connected to the electrode assembly and protruding to the outside of the cap plate through a terminal hole formed in the cap plate, and a lead tab respectively connecting the positive electrode and the negative electrode of the electrode assembly to the electrode terminal. For example, the electrode terminal penetrates the terminal hole through an insulation structure. When a plurality of rechargeable battery cells are connected in series or in parallel, the electrode terminal may be fastened by an additional nut via a bus bar connected to the outer side of the cap plate. 
         [0005]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY 
       [0006]    Embodiments are directed to a rechargeable battery, which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art. 
         [0007]    It is therefore a feature of an embodiment to provide a rechargeable battery with an electrode terminal having strong weldability on an inner side of a cap plate, while having an improved fastening force on an outer side of the cap plate. 
         [0008]    At least one of the above and other features and advantages may be realized by providing a rechargeable battery, including an electrode assembly including wound positive and negative electrodes with a separator therebetween, a case configured to contain the electrode assembly, a cap plate configured to seal an opening of the case, the cap plate including a terminal hole therethrough, an electrode terminal through the terminal hole of the cap plate, the electrode terminal including a terminal through-out portion extending through the terminal hole, a terminal plate connected to the terminal through-out portion outside the case, and a fastening portion including a terminal fastening portion connected to the terminal plate, and a lead tab inside the case, the lead tab connecting the terminal through-out portion of the electrode terminal to the electrode assembly. 
         [0009]    The terminal through-out portion and the terminal plate may include different materials, and the terminal plate and the terminal fastening portion may include a substantially same material. 
         [0010]    The terminal fastening portion and the terminal plate may include a material having a higher mechanical strength than the material of the terminal through-out portion. 
         [0011]    The terminal through-out portion may include copper or aluminum, and the terminal plate and the terminal fastening portion include steel. 
         [0012]    An interface between the terminal plate and the terminal fastening portion may consist essentially of a material of the terminal plate, and an interface between the terminal through-out portion and the terminal plate may include a material other than materials of the terminal through-out portion and the terminal plate. 
         [0013]    The terminal plate may include a through-out portion hole and a protruding portion on at least one side of the through-out portion hole, the terminal through-out portion penetrating through the through-out portion hole. 
         [0014]    The protruding portion may include a first protruding portion and a second protruding portion separated from each other along a first direction to be on different sides of the through-out hole portion, the first and second protruding portions extending along a second direction perpendicular to the first direction. 
         [0015]    The terminal fastening portion may include a plate portion inserted between the first and second protruding portions, and a screw thread portion integral with and protruding from the plate portion. 
         [0016]    The screw thread portion may be a male thread. 
         [0017]    The screw thread portion may be a female thread. 
         [0018]    The protruding portion may further include a third protruding portion and a fourth protruding portion separated along the second direction to be on different sides of the through-out portion hole, the third and fourth protruding portions extending along the first direction. 
         [0019]    The first, second, third, and fourth protruding portions may be connected to each other to define a quadrangular shape. The terminal fastening portion may include a plate portion having a quadrangular shape corresponding to that of the protruding portion and a screw thread portion integrally extending from the plate portion, the plate portion being inserted into the quadrangularly-shaped protruding portion. 
         [0020]    The rechargeable battery may further include fifth and sixth protruding portions, the first through sixth protruding portions being connected with each other to define a hexagonal shape. The terminal fastening portion may include a plate portion having a hexagonal shape corresponding to that of the protruding portion and a screw thread portion integrally extending from the plate portion, the plate portion being inserted into the hexagonally-shaped protruding portion. 
         [0021]    At least one of the above and other features and advantages may also be realized by providing a method of forming a rechargeable battery, including forming an electrode assembly including wound positive and negative electrodes with a separator therebetween, forming a case configured to contain the electrode assembly, forming a cap plate configured to seal an opening of the case, the cap plate including a terminal hole therethrough, forming an electrode terminal through the terminal hole of the cap plate, the electrode terminal including a terminal through-out portion extending through the terminal hole, a terminal plate connected to the terminal through-out portion outside the case, and a fastening portion including a terminal fastening portion connected to the terminal plate, and forming a lead tab connecting the terminal through-out portion of the electrode terminal to the electrode assembly inside the case. 
         [0022]    The terminal through-out portion and the terminal plate may be connected to each other by caulking, and the terminal plate and the terminal fastening portion may be connected to each other by welding. 
         [0023]    The terminal through-out portion and the terminal plate may be formed of different materials, and the terminal plate and the terminal fastening portion may be formed of a substantially same material. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]    The above and other features and advantages will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings, in which: 
           [0025]      FIG. 1  illustrates a perspective view of a rechargeable battery according to a first exemplary embodiment. 
           [0026]      FIG. 2  illustrates a cross-sectional view of  FIG. 1 , taken along the line II-II. 
           [0027]      FIG. 3  illustrates an exploded perspective view of an electrode terminal. 
           [0028]      FIG. 4  illustrates a cross-sectional view of an electrode terminal and a bus bar in a fastened state. 
           [0029]      FIG. 5  illustrates an exploded perspective view of an electrode terminal of a rechargeable battery according to a second exemplary embodiment. 
           [0030]      FIG. 6  illustrates an exploded perspective view of an electrode terminal of a rechargeable battery according to a third exemplary embodiment. 
           [0031]      FIG. 7  illustrates a cross-sectional view of an electrode terminal and a bus bar of a rechargeable battery in a fastened state according to a fourth exemplary embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0032]    Korean Patent Application No. 10-2010-0047712, filed on May 20, 2010, in the Korean Intellectual Property Office, and entitled: “Rechargeable Battery,” is incorporated by reference herein in its entirety. 
         [0033]    Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0034]    In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
         [0035]      FIG. 1  illustrates a perspective view of a rechargeable battery according to a first exemplary embodiment, and  FIG. 2  illustrates a cross-sectional view of  FIG. 1  along line II-II. Referring to  FIG. 1  and  FIG. 2 , a rechargeable battery  100  of the first exemplary embodiment may include a case  20  for containing an electrode assembly  10 , a cap plate  30  sealing an opening formed at one side of the case  20 , electrode terminals  41  and  42  through the cap plate  30 , and lead tabs  51  and  52  connecting respective electrode terminals  41  and  42  with the electrode assembly  10 , e.g., by welding. 
         [0036]    The electrode assembly  10  may include an insulating separator  13 , a positive electrode  11 , and a negative electrode  12 . The positive electrode  11  and the negative electrode  12  may be disposed at both sides of the separator  13 , and the electrode assembly  10  may be formed in a jelly roll shape by winding the positive and negative electrodes  11  and  12  together with the separator  13 . The positive electrode  11  and the negative electrode  12  respectively include a current collector formed as a thin plate metal foil and an active material coated on the surface of the current collector. In addition, the positive electrode  11  and the negative electrode  12  may be respectively partitioned to a coated region, i.e., where the active material is coated on the current collector, and uncoated regions  111  and  121 , i.e., where the current collector is not coated by the active material. The coated region forms the most of the positive and electrodes  11  and  12  in the electrode assembly  10 , and the uncoated regions  111  and  121  are respectively disposed at both sides of the coated region in the jelly roll state. 
         [0037]    The uncoated regions  111  and  121  of the respective positive and negative electrodes  11  and  12  may be connected to respective lead tabs  51  and  52 , and may have substantially same structures. Thus, the uncoated region  111  and the lead tab  51  formed at the positive electrode  11  side will be exemplarily described. The lead tab  51  may include a connection portion  511  connected to the electrode terminal  41  and a current collecting region  512  extending from the connection portion  511  toward a bottom of the case  20 . The collecting region  512  may be bent relatively to the connection portion  511 , e.g., may be perpendicular thereto, and may be connected to the uncoated region  111 , e.g., by ultrasonic welding or laser welding. The connection portion  511  may include a fastening hole  513  ( FIG. 3 ) opened toward the electrode terminal  41  for connection with the electrode terminal  41 . 
         [0038]    The case  20  may outline the rechargeable battery  100 , and may be formed of a conductive metal, e.g., aluminum, aluminum alloy, or nickel-plated steel. The case  20  provides a space for installing the electrode assembly  10 . For example, the case  20  may have a hexahedron shape having an opening at one side for receiving a hexahedral-shaped electrode assembly  10 . The opening of the case  20  faces upward in  FIGS. 1 and 2 . 
         [0039]    The cap plate  30  may be formed as a thin plate, and may be coupled to the opening of the case  20  to seal the opening. While blocking the inside of the sealed case  20  from the outside, the cap plate  30  may connect the inside and the outside of the case  20  as necessary. For example, the cap plate  30  may include an electrolyte solution inlet  32  for insertion of an electrolyte solution into the sealed case  20 . After insertion of the electrolyte solution, the electrolyte solution inlet  32  may be sealed by a sealing cap  33 . 
         [0040]    The cap plate  30  may further include a vent hole  35  and a vent plate  34 , e.g., formed of a plate thinner than the cap plate  30 , welded to the vent hole  35 . When the internal pressure of the case  20  is increased over a predetermined level, the vent plate  34  is ruptured by gas generated through charging and discharging of the electrode assembly  10  to prevent explosion of the rechargeable battery  100 . 
         [0041]    The electrode terminals  41  and  42  may be respectively provided in terminal holes  311  and  312  ( FIG. 4 ) through the cap plate  30  to draw out the positive and negative electrodes  11  and  12  of the electrode assembly  10 . For example, the electrode terminals  41  and  42  may extend through respective terminal holes  311  and  312 , while outer insulators  431  and  432 , as well as inner insulators  441  and  442 , may electrically insulate between each of the electrode terminals  41  and  42  and the cap plate  30 . The terminal holes  311  and  312 , the inner insulators  441  and  442 , and the outer insulators  431  and  432  may be formed in the two electrode terminals  41  and  42  with the same structure. Therefore, the electrode terminal  41 , the terminal hole  311 , the inner insulator  441 , and the outer insulator  431  at one side will be exemplarily described. 
         [0042]    As illustrated in  FIG. 2 , the outer insulator  431  may be partially inserted into the terminal hole  311  from the outside of the cap plate  30  to electrically insulate the electrode terminal  41  and the cap plate  30 . That is, the outer insulator  431  insulates the outer surface of the electrode terminal  41  and the outer surface of the cap plate  30 , and simultaneously insulates the outer surface of the electrode terminal  41  and an inner surface of the terminal hole  311 . The inner insulator  441  electrically insulates the cap plate  30  and the lead tab  51  in the inside of the cap plate  30  corresponding to the terminal hole  311 . That is, the inner insulator  441  insulates the upper surface of the connection portion  511  of the lead tab  51  and the inner surface of the cap plate  30 . 
         [0043]      FIG. 3  illustrates a detailed, exploded perspective view of the electrode terminal  41 .  FIG. 4  illustrates a cross-sectional view of the electrode terminal  41  and a bus bar in a fastened state. 
         [0044]    Referring to  FIG. 3  and  FIG. 4 , the electrode terminal  41  according to example embodiments may be formed to maintain excellent weldability with the lead tab  51  at the inner side of the cap plate  30 , i.e., in the interior of the case  20 , and to have a strong fastening force at the outer side of the cap plate  30 , i.e., in the exterior of the case  20 . Therefore, the electrode terminal  41  may include a terminal through-out portion  61 , a terminal plate  62 , and a terminal fastening portion  63  that are separately fastened and connected, as will be explained in detail below. That is, the separately formed terminal through-out portion  61 , terminal plate  62 , and terminal fastening portion  63  may form the electrode terminal  41  by being fastened and connected to each other. Thus, the materials and connection methods of the terminal through-out portion  61 , the terminal plate  62 , and the terminal fastening portion  63  of the electrode terminal  41  may be selectively adjusted to provide strong connections both inside and outside the case  20 . 
         [0045]    In other words, in the electrode terminal  41 , the terminal through-out portion  61  may be connected to the lead tab  51  inside the case  20  in order to maintain excellent weldability with the connection portion  511  of the lead tab  51  at the inner side of the cap plate  30 . Further, the terminal fastening portion  63  may be formed outside the case  20  in order to increase torque durability when being fastened with a nut  72  of a bus bar  71  at the outer side of the cap plate  30 , thereby providing a strong fastening force. In this case, the terminal plate  62  may be fastened to the terminal through-out portion  61  and may be connected to the terminal fastening portion  63 . That is, the terminal plate  62  may connect the terminal through-out portion  61  and the terminal fastening portion  63 , thereby enabling the electrode terminal  41  to exhibit both excellent weldability and strong fastening force. 
         [0046]    In detail, the terminal through-out portion  61  and the terminal plate  62  may be formed of different materials, and therefore, may be fastened to each other via caulking. As such, a fastening force, e.g., via caulking, between the terminal through-out portion  61  and the terminal plate  62  may be increased despite the different materials, thereby preventing deterioration of weldability between the terminal through-out portion  61  and the connection portion  511  of the lead tab  51 . The terminal plate  62  and the terminal fastening portion  63  may be formed of the same material, and therefore, may be welded to each other. As such, a fastening force between the terminal fastening portion  63  and the nut  72  may be reinforced. In other words, the terminal plate  62  and the terminal fastening portion  63  may be coupled by welding so that they have strong weldability. As the different parts of the electrode terminal  41  are formed of different materials and are connected to each other by different methods, an interface between the terminal plate  62  and the terminal fastening portion  63  may consist essentially of a material of the terminal plate, i.e., due to the welding, and an interface between the terminal through-out portion  61  and the terminal plate  62  may include a material other than materials of the terminal through-out portion  61  and the terminal plate  62 , i.e., due to the caulking. 
         [0047]    The terminal fastening portion  63  and the terminal plate  62  may be formed of a mechanically stronger material, i.e., a material capable of withstanding a higher stress application, than the terminal through-out portion  61 . For example, the terminal through-out portion  61  may be made of copper or aluminum, and the terminal plate  62  and terminal fastening portion  63  may be made of steel. Thus, when the nut  72  is mounted on the terminal fastening portion  63  with the bus bar  71 , the terminal fastening portion  63  may endure strong torque and the terminal plate  62  and the terminal fastening portion  63  may maintain the strong welding state against the strong torque. 
         [0048]    The terminal through-out portion  61  may include a substantially flat member extending between the connection portion  511  of the lead tab  51  and the cap plate  30 , e.g., the inner insulator  441  may separate the flat member of the terminal through-out portion  61  from the cap plate  30 . A vertical protruding portion may extend from the flat member of the terminal through-out portion  61  through the terminal hole  311  to be inserted into the terminal plate  62 , e.g., the outer insulator  431  may separate the vertical protruding portion from the cap plate  30 . The flat member and the vertical protruding portion of the terminal through-out portion  61  may be integral, and may further include a terminal portion below the connection portion  511  of the lead tab  51  to increase stability between the lead tab  51  and the terminal through-out portion  61 . 
         [0049]    The terminal plate  62  may include a through-out hole  621  and at least one protruding portion  622  at one side of the through-out hole  621 . The through-out hole  621  may be aligned with the terminal through-out portion  61 , i.e., with the vertical protruding portion of the terminal through-out portion  61 , so the terminal through-out portion  61  may penetrate the through-out hole  621 . For example, the through-out hole  621  may have a step at the plane center of the terminal plate  62 , e.g., so the terminal through-out portion  61  may be inserted therein. For example, an upper surface of the protruding portion  622  may extend above the through-out hole  621 , and the through-out hole  621  and the terminal through-out portion  61  may be deformed from the dash-dot line state to the solid line state and then fastened to each other by caulking. 
         [0050]    For example, the protruding portion  622  of the terminal plate  62  may be formed at one side of the through-out hole  621 . In another example, as shown in  FIG. 3  and  FIG. 4 , the protruding portion  622  may include a first protruding portion  221  and a second protruding portion  222  separated from each other along a first direction (x-axis direction) to be at both sides of the through-out hole  621  and to extend along a second direction (y-axis direction) perpendicular to the first direction. When the terminal fastening portion  63  is welded to the terminal plate  62 , the protruding portion  622  supports at least one side of the terminal fastening portion  63  to prevent rotation of the terminal fastening portion  63  when the terminal fastening portion  63  receives torque. The first and second protruding portions  221  and  222  may support both sides of the terminal fastening portion  63 , so that rotation of the terminal fastening portion  63  can be effectively prevented. In addition, the terminal through-out portion  61  is fastened to the through-out hole  621  at one side and simultaneously caulked and welded to the fastening hole  513  in the connection portion  511  of the lead tab  51 , and therefore, the lead tab  51 , the terminal plate  62 , and the terminal fastening portion  63  may be electrically connected. 
         [0051]    The terminal fastening portion  63  may include a plate portion  411  inserted between the first and second protruding portions  221  and  222  of the terminal plate  62 , e.g., to cover the through-out hole  621 . The plate portion  411  may be welded to the terminal plate  62 , and a screw thread portion  412 , e.g., integrally formed with the plate  411 , may extend vertically from the plate portion  411  away from the terminal plate  62 . For example, when the plate portion  411  is inserted between the first and second protruding portions  221  and  222  of the terminal plate  62 , the plate portion  411  may completely fill a space between the first and second protruding portions  221  and  222 , and upper surfaces of the plate portion  411  and the first and second protruding portions  221  and  222  may be substantially coplanar. Therefore, rotation of the plate portion  411  may be prevented by the first and second protruding portions  221  and  222 , as well as by welding portions W of the first and second protruding portions  221  and  222 . As such, torque durability of the plate portion  411  with respect to torque transmitted to the screw thread portion  412  may be increased. In other words, the torque transmitted to the screw thread portion  412  is blocked by the first and second protruding portions  221  and  222  through the plate portion  411  and the welding portions W of the first and second protruding portions  221  and  222 . For example, as illustrated in  FIG. 4 , the welding portions W may be at an interface, e.g., at upper surfaces facing away from the cap plate  30 , between the plate portion  411  of the terminal fastening portion  63  and the first and second protruding portions  221  and  222  of the terminal plate  62 . 
         [0052]    As illustrated in  FIG. 4 , the screw thread portion  412  may be inserted to a fastening hole of the bus bar  71  to be fastened with the nut  72  on the bus bar  71 . In this case, the bus bar  71  connects rechargeable batteries  100  arranged adjacent to each other in series or in parallel. 
         [0053]      FIG. 5  illustrates an exploded perspective view of an electrode terminal of a rechargeable battery according to a second exemplary embodiment. Referring to  FIG. 5 , in an electrode terminal  81  of the second exemplary embodiment, a protruding portion  722  of a terminal plate may include the first and second protruding portions  221  and  222  of the first exemplary embodiment, and a third protruding portion  223  and a fourth protruding portion  224  separated from each other along the second direction, i.e., along the y-axis, to be on both sides of the through-out hole  621  and to extend along the first direction, i.e., along the x-axis. 
         [0054]    The protruding portion  722 , i.e., the first, second, third, and fourth protruding portions  221 ,  222 ,  223  and  224 , may be formed independently, and the first through fourth protruding portions  221  through  224  may be connected with each other to form a quadrangle shape extending above and surrounding the through-out hole  621 . The plate portion  411  in the terminal fastening portion  63  may be formed in a quadrangular shape corresponding to the shape of the protruding portion  722 , so the plate portion  411  may be inserted into the protruding portion  722  and welded thereto. In this case, torque transmitted to the screw thread portion  412  is blocked by the first, second, third, and fourth protruding portions  221 ,  222 ,  223 , and  224 , and is blocked by the plate portion  411  and welding portions of the first, second, third, and fourth protruding portions  221 ,  222 ,  223 , and  224 . The larger number of the protruding portions in the protruding portion  722  of the second exemplary embodiment may provide a stronger fastening force of the terminal fastening portion  63  than that of the first exemplary embodiment. 
         [0055]      FIG. 6  illustrates an exploded perspective view of an electrode terminal of a rechargeable battery according to a third exemplary embodiment. Referring to  FIG. 6 , in an electrode terminal  82  of the third exemplary embodiment, first, second, third, fourth, fifth, and sixth protruding portions  331 ,  332 ,  333 ,  334 ,  335 , and  336  of a protruding portion  822  may be connected with each other to form a hexagonal space surrounding a through-out portion hole  621 . A plate portion  413  in a terminal fastening portion  64  may be formed to have a hexagonal shape inserted into the hexagonal shape of the protruding portion  822  and welded thereto. In this case, a torque transmitted to the screw thread portion  412  is blocked by the first through sixth protruding portions  331  through  336  via the plate portion  413  and the welding portions of the protruding portion  822 . The protruding portion  822  of the third exemplary embodiment may have a similar fastening force, as compared to the protruding portion  722  of the second exemplary embodiment, and may be modified to various structures. Thus, the protruding portion  822  and the plate portion  413  may have any suitable polygonal shape, e.g., quadrangular, hexagonal, etc. 
         [0056]      FIG. 7  illustrates a cross-sectional view of an electrode terminal and a bus bar of a rechargeable battery  200  in a fastened state according to a fourth exemplary embodiment. As illustrated in  FIG. 7 , a screw thread portion  414  of a terminal fastening portion  65  formed in an electrode terminal  83  may be formed as a female thread. Compared to the first to third exemplary embodiments, a spacer  66  and a bolt  67  that supports the spacer  66  by being screw thread-coupled to the screw thread portion  414  may be used to fasten terminal fastening portions  65  of cells of neighboring rechargeable batteries  200  with the bus bar  71  instead of using the nut  72 . The bolt  67  may be fastened to the screw thread portion  414 , and therefore, the bus bar  71  may press the first and second protruding portions  221  and  222  of the terminal plate  62  through the spacer  66 . 
         [0057]    As described above, according to the exemplary embodiments, the electrode terminal may include the terminal through-out portion, the terminal plate, and the terminal fastening portion, which may be separately formed and then fastened and connected to each other. As such, each part of the electrode terminal may be formed of a different material. Thus, strong weldablity between the terminal through-out portion and the lead tab may be maintained at the inner side of the cap plate, and simultaneously, an improved fastening force between the terminal fastening portion and the terminal plate at the outer side of the cap plate may be provided. That is, when a nut is fastened to a bus bar in the terminal fastening portion, a fastening torque of the nut may be reinforced, and when the bus bar is coupled to the terminal fastening portion by welding, weldablity between the terminal fastening portion and the bus bar may be enhanced. 
         [0058]    In contrast, when a conventional electrode terminal is formed of a single material, it may be difficult to have both a strong fastening force with the nut or bus bar while maintaining weldability with the lead tab. For example, when the conventional electrode terminal is made of copper or aluminum, it may exhibit excellent weldability with a copper or aluminum lead tab, but it may not have a strong fastening force with a steel nut or bus bar outside the cap plate. In such a case, the nut may be loosened or the welding portion of the electrode terminal and the bus bar may be separated due to vibration, temperature, or impact, thereby increasing contact resistance. 
         [0059]    Exemplary embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims. 
       DESCRIPTION OF SYMBOLS 
       [0060]      
         [0000]    
       
         
               
               
             
               
             
               
               
             
               
             
               
               
             
           
               
                   
               
             
             
               
                  10: electrode assembly 
                  11: positive electrode 
               
               
                  12: negative electrode 
                  13: separator 
               
               
                  20: case 
                  30: cap plate 
               
               
                  32: electrolyte solution inlet 
                  33: sealing cap 
               
               
                  34: vent plate 
                  35: vent hole 
               
               
                  41, 42, 81, 82, 83: electrode terminal 
                  51, 52: lead tab 
               
               
                  61: terminal through-out 
                  62: terminal plate 
               
               
                  63, 64, 65: terminal fastening portion 
                  66: spacer 
               
               
                  67: bolt 
                  71: bus bar 
               
               
                  72: nut 
                 100, 200: rechargeable battery 
               
               
                 111, 121: uncoated region 
                   
               
             
          
           
               
                 221, 222, 223, 224: first through fourth protruding portions 
               
             
          
           
               
                 311, 312: terminal hole 
                   
               
             
          
           
               
                 331, 332, 333, 334, 335, 336: first through sixth protruding portions 
               
             
          
           
               
                 411, 413: plate portion 
                 412, 414: screw thread portion 
               
               
                 431, 432: outer insulator 
                 441, 442: inner insulator 
               
               
                 511: connection portion 
                 512: current collecting portion 
               
               
                 513: fastening hole 
                 621: through-out hole 
               
               
                 622, 722, 822: protruding portion