Patent Publication Number: US-2022223984-A1

Title: Rechargeable battery

Description:
TECHNICAL FIELD 
     The present invention relates to a rechargeable battery, and more particularly, to an ultra-compact rechargeable battery. 
     BACKGROUND ART 
     A rechargeable battery differs from a primary battery in that it can be repeatedly charged and discharged, while the latter is incapable of being recharged. A low-capacity rechargeable battery is used in a portable electronic device such as a mobile phone, a notebook computer, and a camcorder, and a large-capacity rechargeable battery is widely used as a power source for driving a motor of a hybrid vehicle and the like. 
     As typical rechargeable batteries, there are a nickel-cadmium (Ni—Cd) battery, a nickel-hydrogen (Ni-MH) battery, a lithium (Li) battery, a lithium ion (Li-ion) rechargeable battery, etc. Particularly, the Li-ion rechargeable battery has an operating voltage that is three times as high as those of the Ni—Cd battery and the Ni-MH battery that are widely used as a power supply for portable electronic devices. In addition, the lithium ion rechargeable battery has been widely used because its energy density per unit weight is high. 
     Particularly, as demand for wearable devices such as a headphone, an earphone, a smartwatch, and a body-worn medical device using Bluetooth has increased, a need for a rechargeable battery having a high energy density and an ultra-small size has been increasing. 
     As an example, the ultra-small rechargeable battery includes a coin cell or a button cell. Since the coin cell or button cell has a low overall height, when a thickness of a portion in which an electrode terminal thereof is installed increases, battery capacity may be reduced. In addition, since end portions of a bent lead tab are adjacent to both ends of an electrode assembly wound with a lower height than a diameter thereof, workability for welding end portions of the lead tab and the electrode terminal is deteriorated. 
     DISCLOSURE 
     One aspect of the present invention is to provide a rechargeable battery that increases capacity by reducing a thickness at which an electrode terminal is installed and that easily connects a lead tab to the electrode terminal. 
     An embodiment of the present invention provides a rechargeable battery including: an electrode assembly formed by disposing and winding a separator between a first electrode and a second electrode; a case that faces one of the both wound ends of the electrode assembly and accommodates the electrode assembly; a cap plate that faces the other of the wound both ends and closes and seals an opening of the case; an electrode terminal installed by interposing an insulating material in a terminal hole formed in one of the cap plate and the case; a first lead tab connecting one of the first electrode and the second electrode to the electrode terminal; and a second lead tab connecting the other of the first electrode and the second electrode to the other of the cap plate and the case. 
     The rechargeable battery according to the embodiment of the present invention may further include a terminal plate coupled to the electrode terminal and connected to the first lead tab together with the electrode terminal. 
     The insulation material may include a first gasket disposed at the outside of the terminal hole in a thickness direction of the cap plate and inserted into an inner surface of the terminal hole, and a second gasket disposed at the inside of the terminal hole and coupled to an inserted outer surface of the first gasket, and the terminal plate may be disposed inside the second gasket. 
     The electrode terminal may include a first plate portion extending from and supported on an outer surface of the first gasket, a pillar portion connected to the first plate portion and inserted into the first gasket portion, and a second plate portion connected to the pillar portion and extending from and supported on an inner surface of the terminal plate. 
     The second gasket may be provided with a protrusion protruding from an outer circumference thereof toward the electrode assembly to form a gap between an inner circumferential surface of the protrusion and an outer circumferential surface of the terminal plate. 
     The terminal plate may be coupled to the pillar portion to be connected to the second plate portion, and the second lead tab may be connected to the case. 
     The terminal hole may be formed in the cap plate, the first gasket may be disposed on the outside of the cap plate, and the second gasket may be disposed on the inside of the cap plate. 
     The first gasket may be provided with an insertion portion inserted into the terminal hole, and a diameter of the terminal hole and an inner diameter of the second gasket may be the same as an outer diameter of the insertion portion. 
     The cap plate may be provided with a first accommodating groove having a step to accommodate the first gasket. 
     The terminal plate may be provided with a second accommodating groove having a step to accommodate the second plate portion, and a lower end of the insertion portion may form the same plane as the second accommodating groove. 
     An upper surface of the second plate portion may support the second accommodating groove of the terminal plate and a lower end of the insertion portion. 
     The rechargeable battery according to the embodiment of the present invention may further include a first insulating member interposed between the second lead tab and the electrode assembly, in a bottom side of the case. 
     The rechargeable battery according to the embodiment of the present invention may further include a second insulating member interposed between the first lead tab and the electrode assembly, in the cap plate side. 
     The rechargeable battery according to the embodiment of the present invention may further include a third insulating member interposed between the first lead tab and the cap plate. 
     A height (H) may be set as a minimum distance between outer planes of the case and the cap plate, a diameter (D) may be set as a maximum distance of an outer circumference of the case, and a ratio of the height to the diameter may be 1 or less (H/D≤1). 
     The terminal plate may be coupled to the pillar portion to be connected to the second plate portion, and the second lead tab may be connected to the cap plate. 
     The terminal hole may be formed in the case, the first gasket may be disposed on the outside of the case, and the second gasket may be disposed on the inside of the case. 
     The case may be provided with a first accommodating groove having a step to accommodate the first gasket. 
     The terminal plate may be provided with a second accommodating groove having a step to accommodate the second plate portion, an upper end of the insertion portion may form the same plane as the second accommodating groove, and a lower surface of the second plate portion may be supported on the second accommodating groove of the terminal plate and an upper end of the insertion portion. 
     The rechargeable battery according to the embodiment of the present invention may further include: a first insulating member interposed between the second lead tab and the electrode assembly, in the cap plate side; a second insulating member interposed between the first lead tab and the electrode assembly, in a bottom side of the case; and a third insulating member interposed between the first lead tab and the bottom of the case. 
     As such, according to the embodiment of the present invention, by interposing an insulating material in a terminal hole formed in a case or cap plate to install an electrode terminal and by connecting the electrode terminal to an electrode assembly with a first lead tab, it is possible to increase capacity by reducing a thickness at which the electrode terminal is installed. 
     In addition, according to the embodiment of the present invention, by laser-welding a first lead tab to a second plate portion or terminal plate having a thin thickness of an electrode terminal, it is possible to easily connect the first lead tab and the electrode terminal. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an exploded perspective view of a rechargeable battery according to a first embodiment of the present invention. 
         FIG. 2  illustrates a cross-sectional view taken along line II-II of  FIG. 1 . 
         FIG. 3  specifically illustrates a cross-sectional view of a coupling state between a terminal hole and an electrode terminal formed in a cap plate of  FIG. 2 . 
         FIG. 4  illustrates an exploded perspective view of a rechargeable battery according to a second embodiment of the present invention. 
         FIG. 5  illustrates a cross-sectional view taken along line V-V of  FIG. 4 . 
         FIG. 6  specifically illustrates a cross-sectional view of a coupling state between a terminal hole and an electrode terminal formed in a case of  FIG. 5 . 
     
    
    
     MODE FOR INVENTION 
     The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
     A rechargeable battery according to an embodiment of the present invention is an ultra-small battery, and may be a coin cell or button cell. Here, the coin cell or button cell is a thin coin-type or button-type cell, which means a battery having a ratio (height/diameter) of a height to a diameter of 1 or less. 
     Since the coin cell or the button cell is mainly cylindrical, a horizontal cross-section is circular, but the present invention is not limited thereto, and a horizontal cross-section may be oval or polygonal. In this case, the diameter means a maximum distance based on a horizontal direction of the battery, and the height means a minimum distance from a flat bottom surface of the battery to a flat top surface of the battery. 
     However, the present invention is not limited to the coin cell or the button cell that is an example of the present invention, and a battery of the present invention may be a cylindrical-type or pin-type of battery. However, hereinafter, a case in which a rechargeable battery according to an embodiment of the present invention is a coin cell or a button cell will be exemplarily described in detail. 
       FIG. 1  illustrates an exploded perspective view of a rechargeable battery according to a first embodiment of the present invention, and  FIG. 2  illustrates a cross-sectional view taken along line II-II of  FIG. 1 . Referring to  FIG. 1  and  FIG. 2 , a rechargeable battery  1  of the first embodiment includes an electrode assembly  10 , a case  20 , a cap plate  30 , an electrode terminal  40 , a first lead tab  51 , a second lead tab  52 , and a terminal plate  53 . 
     The electrode assembly  10  includes a first electrode  11  (for example, a negative electrode) and a second electrode  12  (for example, a positive electrode) provided on respective surfaces of a separator  13  that is an electrical insulating material, and is formed by winding the first electrode  11 , the separator  13 , and the second electrode  12 . Accordingly, the electrode assembly  10  may have a jelly-roll shape, and is configured to charge and discharge a current. 
     In this case, a winding axis of the electrode assembly  10  may be arranged in parallel with a height direction of the case  20 , and a lower surface (one of respective ends of winding) of the electrode assembly  10  and an upper surface (the other of respective ends of winding) thereof may be flat and parallel to each other. 
     The electrode assembly  10  is provided with a center pin  15  at a position of the winding axis. When the first and second lead tabs  51  and  52  are welded to the electrode terminal  40  and the case  20 , the center pin  15  allows the first lead tab  51  and the electrode terminal  40  to be in close contact with each other and allows the second lead tab  52  and the case  20  to be in close contact with each other, so that it is possible to improve welding performance. The center pin  15  may be formed as a cylinder to allow a gas and an electrolyte to flow therein. In addition, the center pin may be formed in a circular cylindrical shape (not shown). 
     Hereinafter, in the description, a case in which the first electrode  11  and the second electrode  12  are respectively a negative electrode and a positive electrode will be exemplarily described, but the present invention is not limited thereto, and the first electrode  11  and the second electrode  12  may respectively be a positive electrode and a negative electrode. 
     The negative electrode  11  (first electrode) is formed in a long extending strip shape, and includes a negative electrode coated region that is a region in which a negative electrode active material layer is coated to a current collector of a metal foil (for example, a Cu foil) and a negative electrode uncoated region that is a region in which an active material is not coated. The negative electrode uncoated region may be disposed at one end portion in a length direction of the negative electrode. 
     The positive electrode  12  (second electrode) is formed in a long extending strip shape, and includes a positive electrode coated region that is a region in which a positive electrode active material layer is coated to a current collector of a metal foil (for example, an Al foil) and a positive electrode uncoated region that is a region in which an active material is not coated. The positive electrode uncoated region may be disposed at one end portion in a length direction of the positive electrode. 
     The case  20  allows the electrode assembly  10  to be inserted and accommodated through an opening  21  formed in one side thereof. The case  20  sets a space in which the electrode assembly  10  and an electrolyte are accommodated. For example, the case  20  may have a cylindrical shape with a low height, and may be provided with the circular opening  21  for inserting the cylindrical electrode assembly  10  at an upper end thereof. 
     The cap plate  30  closes and seals the opening  21  of the case  20 , and is coupled to the opening  21  to be closed and sealed by welding. The electrode terminal  40  is installed in a terminal hole  41  formed in the cap plate  30  with an insulating material interposed therebetween. That is, the electrode terminal  40  and the cap plate  30  have different polarities. 
     In the electrode assembly  10 , the first lead tab  51  (negative electrode tab) is fixedly installed on the negative electrode  11 , and the second lead tab  52  (positive electrode tab) is fixedly installed on the positive electrode  12 . Accordingly, in the first embodiment, the electrode terminal  40  has a negative polarity, and the cap plate  30  has a positive polarity. Although not separately shown, the electrode terminal  40  may have a positive polarity, and the cap plate  30  may have a negative polarity. 
     The first lead tab  51  and the second lead tab  52  may be respectively installed in the negative uncoated region and the positive electrode uncoated region, extend parallel to the winding axis, and then have end portions bent toward the winding axis. For example, the bent end portions of the first lead tab  51  and the second lead tab  52  may be disposed on an upper portion (a cap plate  30  side) and a lower portion (a case  20  side) of the electrode assembly  10 , respectively. 
     The first lead tab  51  is made of an electrically conductive material such as copper or nickel, and is electrically connected to the electrode terminal  40  directly or through the terminal plate  53 . For example, the bent end portion of the first lead tab  51  may be connected to the electrode terminal  40  or the terminal plate  53  by laser welding. 
     That is, the terminal plate  53  may be mechanically coupled to the electrode terminal  40 , and the terminal plate  53  may be connected to the bent end portion of the second lead tab  52  together with the electrode terminal  40  by laser welding. 
     The second lead tab  52  is made of an electrically conductive material such as nickel or aluminum, and is electrically connected to the case  20 . For example, the bent end portion of the second lead tab  52  may be connected to an inner bottom surface of the case  20  by laser welding. 
     Insulating materials interposed between the electrode terminal  40  and the terminal hole  41  and around the electrode terminal  40  include a first gasket  61  and a second gasket  62 . The first gasket  61  is disposed at the outside of the terminal hole  41  to be inserted into the terminal hole  41 , so it electrically insulates between the electrode terminal  40  and the terminal hole  41  and between the electrode terminal  40  and the cap plate  30  at the outside of the cap plate  30 . 
     Since the second gasket  62  is disposed at the inside the terminal hole  41  to be coupled to an outside thereof in which the first gasket  61  is inserted, it electrically insulates between the electrode terminal  40  and the cap plate  30  inside the cap plate  30 . 
     The outside means an outer side of the rechargeable battery  1  in a thickness direction of the cap plate  30 , and the inside means an inner side of the rechargeable battery  1  in the thickness direction of the cap plate  30 . 
     The terminal plate  53  is disposed at the inside of the second gasket  62 , and is electrically connected to the electrode terminal  40 . Accordingly, the second gasket  62  further electrically insulates between the terminal plate  53  and the cap plate  30 . 
     As an example, the electrode terminal  40  is formed as a rivet, and a completed structure thereof is formed after a riveting process. The first gasket  61  is interposed in the terminal hole  41  at the outside of the cap plate  30  to insert a rivet in a state before the electrode terminal  40  is formed, and the second gasket  62  and the terminal plate  53  are coupled to an outer surface of the first gasket  61  at the inside of the cap plate  30 , and then the rivet is deformed to form the electrode terminal  40 . 
     After riveting, the electrode terminal  40  includes a first plate portion  401 , a pillar portion  403 , and a second plate portion  402 . The first plate portion  401  is extended and supported in a wide area on an outer surface of the first gasket  61 . The second plate portion  402  is extended and supported in a wide area on an inner surface of the terminal plate  53 . The pillar portion  403  is inserted into the first gasket  61  to connect the first plate portion  401  and the second plate portion  402  to each other. 
     Accordingly, while the first and second plate portions  401  and  402  are disposed at the outside and inside of the terminal hole  41  with the cap plate  30  therebetween and while the first and second gaskets  61  and  62  and the terminal plate  53  are installed in the terminal hole  41 , the electrode terminal  40  is installed. 
       FIG. 3  specifically illustrates a cross-sectional view of a coupling state between a terminal hole and an electrode terminal formed in a cap plate of  FIG. 2 . Referring to  FIG. 2  and  FIG. 3 , the second gasket  62  is provided with a protrusion  621  protruding from an exterior circumference thereof towards the electrode assembly  10 . 
     In a diameter direction of the cap plate  30 , the terminal plate  53  is coupled to the inside of the protrusion  621  of the second gasket  62 . The terminal plate  53  is coupled to the inner surface of the second gasket  62 . In this case, a gap (G) is formed between an inner circumferential surface of the protrusion  621  and an outer circumferential surface of the terminal plate  53  in the diameter direction. The gap (G) forms an assembly tolerance of the terminal plate  53 , and may accommodate a deformation amount of the terminal plate  53  due to a riveting pressure deviation. 
     In the first embodiment, the terminal plate  53  connected to the first lead tab  51  is coupled to the pillar portion  403  of the electrode terminal  40  to be connected to the second plate portion  402 , and the second lead tab  52  is connected to the case  20 . 
     The terminal hole  41  is formed in the cap plate  30 , the first gasket  61  is disposed on the outside of the cap plate  30 , and the second gasket  62  is disposed on the inside of the cap plate  30 . 
     The first gasket  61  is provided with an insertion portion  611  that is inserted into the terminal hole  41 , and a diameter of the terminal hole  41  and an inner diameter of the second gasket  62  are the same as an outer diameter of the insertion portion  611 . Accordingly, the second gasket  62  may be coupled to the first gasket  61  in an airtight structure inside the cap plate  30 . 
     The cap plate  30  is provided with a first accommodating groove  301  on an outer surface having a step to accommodate the first gasket  61 . Accordingly, the first gasket  61  inserted from the outside of the cap plate  30  is accommodated in the first accommodating groove  301  so that an outer surface of the first gasket  61  and an outer surface of the cap plate  30  may form the same horizontal plane. Accordingly, a thickness of a portion in which the electrode terminal  40  is installed is decreased at the outside, and thus capacity may be increased. 
     In addition, the first plate portion  401  of the electrode terminal  40  is coupled to a third accommodating groove  612  formed on an outer surface of the first gasket  61 , so that an outer surface of the first plate portion  401  and an outer surface of the first gasket  61  may form the same horizontal plane. Accordingly, the thickness of the portion in which the electrode terminal  40  is installed is further decreased at the outside, and thus the capacity may be further increased. 
     The terminal plate  53  is provided with a second accommodating groove  531  having a step difference to accommodate the second plate portion  402 . Accordingly, by accommodating the second plate portion  402  formed inside the cap plate  30 , an inner surface of the second plate portion  402  and an inner surface of the terminal plate  53  may form the same horizontal plane. Accordingly, the thickness of the portion in which the electrode terminal  40  is installed is decreased from the inside, and thus the capacity may be increased. 
     In this case, an upper surface of the second plate portion  402  supports lower ends of the second accommodating groove  531  of the terminal plate  53  and the insertion portion  611  of the first gasket  61 . That is, the lower end of the insertion portion  611  of the first gasket  61  forms the same plane as the second accommodating groove  531 , so that an inner surface of the second plate portion  402  and an inner surface of the terminal plate  53  may form the same horizontal plane. 
     The first lead tab  51  is directly laser-welded to the second plate portion  402  with a thin thickness, or is mechanically coupled to the pillar portion  403  to be electrically connected to the second plate portion  402  and to be laser-welded to the terminal plate  53  with a thin thickness, so the process of connecting the first lead tab  51  to the electrode terminal  40  is facilitated. 
     In addition, the second lead tab  51  is directly laser-welded to a bottom of the case  20 . In this case, the center pin  15  supports the first and second lead tabs  51  and  52  to allow the first lead tab  51  and the electrode terminal  40  to closely contact each other and to allow the second lead tab  52  and the case  20  to closely contact each other, thereby improving each welding performance. 
     Referring back to  FIG. 1  and  FIG. 2 , the rechargeable battery  1  of the first embodiment further includes a first insulating member  71  interposed between the second lead tab  52  and the electrode assembly  10 , in a bottom side of the case  20 . The first insulating member  71  electrically insulates between the electrode assembly  10  and the bent second lead tab  52 . 
     The rechargeable battery  1  of the first embodiment further includes, in the cap plate  30  side, a second insulating member  72  interposed between the first lead tab  51  and the electrode assembly  10 , and a third insulating member  73  interposed between the first lead tab  51  and the cap plate  30 . 
     The second insulating member  72  electrically insulates between the electrode assembly  10  and the bent first lead tab  51 . The third insulating member  73  further electrically insulates between the bent first lead tab  51  and the cap plate  30 . 
     In the present embodiment, the first and second insulating members  71  and  72  have a through hole through which the center pin  15  passes so that the center pin  15  more firmly supports the first and second lead tabs  51  and  52 . Although not shown, the first and second insulating members are not provided with a through hole, and the center pin may supports the first and second insulating members to support the first and second lead tabs. 
     Although not shown, the electrode assembly  10  is covered with an insulating tape along an outer circumferential surface in a diameter direction. The insulating tape electrically insulates the external circumferential surface of the electrode assembly  10  from the inner surface of the case  20 , while protecting the outside of the electrode assembly  10 . 
     When the rechargeable battery  1  of the first embodiment is applied to a coin cell or a button cell, the height (H) is set to a minimum distance between the outer planes of the case  20  and the cap plate  30 , and the diameter D is set to a maximum distance of the outer circumference of the case  20 . In addition, a ratio of the height H to the diameter D is 1 or less (H/D≤1). 
     As described above, in the case of the coin cell or the button cell with a low height compared with a diameter, since the connection structure between the electrode terminal  40  and the first lead tab  51  is thinly formed, when they have the same height (H) and diameter (D), compared with a case in which the connection structure is thick, as a size of the electrode assembly  10  increases, the overall capacity of the rechargeable battery  1  may increase. 
     Hereinafter, a second embodiment of the present invention will be described. Compared with the first embodiment, the same components are omitted, and different components are described. 
       FIG. 4  illustrates an exploded perspective view of a rechargeable battery according to a second embodiment of the present invention, and  FIG. 5  illustrates a cross-sectional view taken along line V-V of  FIG. 4 . Referring to  FIG. 4  and  FIG. 5 , as in the rechargeable battery  1  of the first embodiment, the terminal plate  53  is connected to the second plate portion  402  of the electrode terminal  40 . 
     In the rechargeable battery  2  of the second embodiment, the second lead tab  52  is electrically connected to a cap plate  230 . For example, the bent end portion of the second lead tab  52  may be connected to an inner surface of the cap plate  230  by laser welding. 
     A terminal hole  31  is formed in a case  220 . The first gasket  61  is disposed at the outside of the case  220  and inserted into the terminal hole  31 , so it electrically insulates between the electrode terminal  40  and the terminal hole  41  and between the electrode terminal  40  and the case  200  at the outside of the case  220 . 
     The second gasket  62  is disposed inside the case  220  and is disposed inside the terminal hole  31  to be coupled to an inserted outer surface of the first gasket  61 , so that it electrically insulates between the electrode terminal  40  and the case  220  at the inside of the case  220 . 
     The outside means an outer side of the rechargeable battery  2  in a thickness direction of a bottom of the case  200 , and the inside means an inner side of the rechargeable battery  2  in the thickness direction of the bottom of the case  220 . 
     The terminal plate  53  is disposed at the inside of the second gasket  62 , and is electrically connected to the electrode terminal  40 . Accordingly, the second gasket  62  further electrically insulates between the terminal plate  53  and the case  220 . 
       FIG. 6  specifically illustrates a cross-sectional view of the coupling state between the terminal hole and the electrode terminal formed in the case of  FIG. 5 . Referring to  FIG. 5  and  FIG. 6 , the case  220  is provided with a first accommodating groove  201  on an outer surface having a step to accommodate the first gasket  61 . 
     Accordingly, the first gasket  61  inserted from the outside of the case  220  is accommodated in the first accommodating groove  201  so that an outer surface of the first gasket  61  and an outer surface of the case  220  may form the same horizontal plane. Accordingly, a thickness of a portion in which the electrode terminal  40  is installed is decreased at the outside, and thus capacity may be increased. 
     The terminal plate  53  is provided with a second accommodating groove  531  having a step difference to accommodate the second plate portion  402 . Accordingly, by accommodating the second plate portion  402  formed inside the case  220 , an inner surface of the second plate portion  402  and an inner surface of the terminal plate  53  may form the same horizontal plane. Accordingly, the thickness of the portion in which the electrode terminal  40  is installed is decreased from the inside, and thus the capacity may be increased. 
     In this case, a lower surface of the second plate portion  402  is supported on lower ends of the second accommodating groove  531  of the terminal plate  53  and the insertion portion  611  of the first gasket  61 . That is, the upper end of the insertion portion  611  of the first gasket  61  forms the same plane as the second accommodating groove  531 , so that an inner surface of the second plate portion  402  and an inner surface of the terminal plate  53  may form the same horizontal plane. 
     Referring back to  FIG. 4  and  FIG. 5 , the rechargeable battery  2  of the second embodiment further includes a first insulating member  71  interposed between the second lead tab  52  and the electrode assembly  10 , in the cap plate  230  side. The first insulating member  75  electrically insulates between the electrode assembly  10  and the bent second lead tab  52 . 
     The rechargeable battery  2  of the second embodiment further includes, in the bottom side of the case  200 , a second insulating member  76  interposed between the first lead tab  51  and the electrode assembly  10 , and a third insulating member  77  interposed between the first lead tab  51  and the case  220 . 
     The second insulating member  76  electrically insulates between the electrode assembly  10  and the bent first lead tab  51 . The third insulating member  77  further electrically insulates between the bent first lead tab  51  and the bottom of the case  220 . 
     While this invention has been described in connection with what is presently considered to be practical embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
     
       
         
           
               
             
               
                   
               
               
                 &lt;Description of symbols&gt; 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
            
               
                 1, 2: rechargeable battery 
                 10: electrode assembly 
               
               
                 11: first electrode (negative electrode) 
               
               
                 12: second electrode (positive electrode) 
               
               
                 13: separator 
                 20, 220: case 
               
               
                 21: opening 
                 30, 230: cap plate 
               
               
                 31, 41: terminal hole 
                 40: electrode terminal 
               
               
                 51: first lead tab 
                 52: second lead tab 
               
               
                 53: terminal plate 
                 61: first gasket 
               
               
                 62: second gasket 
                 71, 75: first insulating member 
               
               
                 72, 76: second insulating members 
                 73, 77: third insulating member 
               
               
                 201, 301: first accommodating groove 
               
               
                 401: first plate portion 
               
               
                 402: second plate portion 
                 403: pillar portion 
               
               
                 531: second accommodating groove 
                 611: insertion portion 
               
               
                 621: protrusion 
                 D: diameter 
               
               
                 G: gap 
                 H: height