Abstract:
A rechargeable battery that improves a vibration-proof property is provided. The rechargeable battery includes: an electrode assembly including a positive electrode, a negative electrode, and a separator that is disposed between the positive electrode and the negative electrode, a case that houses the electrode assembly, and a cap assembly including terminals that are coupled to the case and that are electrically connected to the electrode assembly, wherein the terminal has a lead tab that is electrically connected to the electrode assembly and a vibration-proof member is installed between the lead tab and the case.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional Application 61/234,561 filed Aug. 17, 2009, in the United States Patent Office, the entire content of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     The described technology relates generally to a rechargeable battery having a member that can absorb vibration and an impact. 
     2. Description of the Related Art 
     A rechargeable battery can be discharged and recharged, unlike a primary battery that cannot be recharged. A low capacity rechargeable battery is often used for a small portable electronic device such as a mobile phone, a laptop computer, and a camcorder, and a large capacity rechargeable battery is often used as a power source for driving a motor such as for a hybrid vehicle. 
     Further a high power rechargeable battery module that uses a high energy density of non-aqueous electrolyte has been developed, and in such a high power rechargeable battery, a plurality of rechargeable batteries for driving a device requiring large electric power, for example, a motor such as an electric vehicle are coupled in series. 
     Further, a high power rechargeable battery module is formed with a plurality of rechargeable batteries that are generally coupled in series, and the rechargeable battery may be formed in a cylindrical shape and a quadrangular shape. 
     The quadrangular shape rechargeable battery includes an electrode assembly in which a positive electrode and a negative electrode are positioned with a separator disposed therebetween, a case having a space that houses the electrode assembly, a cap plate that closes and seals the case and having a terminal hole through which a terminal is inserted, and a terminal that is electrically connected to the electrode assembly and that is inserted into the terminal hole to protrude to the outside of the case. 
     The terminal is electrically connected to the electrode assembly through a lead tab, and the lead tabs are each fixed to the terminal and the electrode assembly. Due to an external vibration or impact, a contact between the lead tab and the electrode assembly and/or a contact between the lead tab and the terminal may become disrupted or ineffective. 
     Such a problem frequently occurs in a rechargeable battery that is applied to an object that continuously vibrates, such as an electric vehicle (EV) and a hybrid electric vehicle (HEV). 
     When a contact between the lead tab and the terminal or the electrode assembly becomes disrupted, an output of the rechargeable battery is deteriorated and much resistance heat occurs in a contact portion thereof. When much heat occurs within the case, an abnormal reaction such as decomposition of an electrolyte solution occurs within the case, and thus the rechargeable battery may explode or ignite. 
     Further, when the electrode assembly does not contact the case for insulation and is suspended to the lead tab, if an external vibration or impact occurs, all loads are concentrated to the terminal and thus the terminal may be deformed or cut. 
     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 
     The described technology has been made in an effort to provide a rechargeable battery having improved durability against vibration and impact. 
     An exemplary embodiment of the present invention provides a rechargeable battery including: an electrode assembly including a positive electrode, a negative electrode, and a separator that is disposed between the positive electrode and the negative electrode, a case that houses the electrode assembly, and a cap assembly including terminals that are coupled to the case and that are electrically connected to the electrode assembly, wherein the terminal has a lead tab that is electrically connected to the electrode assembly and a spacer installed between the lead tab and the case. 
     The spacer has a first support part that is installed between the case and the lead tab and a second support part that is installed between the lead tab and the electrode assembly to be supported to the lead tab. 
     According to an exemplary embodiment of the present invention, as the spacer is installed in the terminal, a terminal can be prevented from shaking due to an external vibration or impact. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a rechargeable battery according to an exemplary embodiment of the present invention. 
         FIG. 2  is a cross-sectional view of the rechargeable battery taken along line II-II of  FIG. 1 . 
         FIG. 3  is an exploded perspective view illustrating a lead tab and an anti-vibration member according to a first exemplary embodiment of the present invention. 
         FIG. 4  is an exploded perspective view illustrating a lead tab and an anti-vibration member according to a second exemplary embodiment of the present invention. 
         FIG. 5  is an exploded perspective view illustrating a lead tab and an anti-vibration member according to a third exemplary embodiment of the present invention. 
         FIG. 6  is a vertical cross-sectional view illustrating the anti-vibration members shown in  FIG. 5  coupled to the lead tab. 
         FIG. 7  is an exploded perspective view illustrating a lead tab and an anti-vibration member according to a fourth exemplary embodiment of the present invention. 
         FIG. 8  is a transverse cross-sectional view illustrating the anti-vibration members shown in  FIG. 6  coupled to the lead tab. 
     
    
    
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 Description of Reference Numerals Indicating  
               
               
                 Primary Elements in the Drawings 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 100: rechargeable battery 
                 10: electrode assembly 
               
               
                   
                  11: positive electrode 
                 12: negative electrode 
               
               
                   
                  13: separator 
                 20: cap assembly 
               
               
                   
                  21: positive terminal 
                 22: negative terminal 
               
               
                   
                  21a, 22a: flange 
                 21b, 22b: lower protrusion 
               
               
                   
                  30: cap plate 
                 34: case 
               
               
                   
                  40, 50: lead tab 
                 51: terminal junction part 
               
               
                   
                  51a: terminal hole 
                 52: side plate 
               
               
                   
                  53: electrode assembly junction part 
                 54: vent hole 
               
               
                   
                  56: anti-vibration member hole 
                 60: anti-vibration member 
               
               
                   
                  61: second support part 
                 62: connecting bar 
               
               
                   
                  65: first support part 
               
               
                   
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION 
     Embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary 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. In the specification and drawings, like reference numerals designate like elements 
       FIG. 1  is a perspective view illustrating a rechargeable battery according to an exemplary embodiment of the present invention, and  FIG. 2  is a cross-sectional view of the rechargeable battery taken along line II-II of  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , a rechargeable battery  100  according to the present exemplary embodiment includes an electrode assembly  10  that is spiral-wound by locating a separator  13 , which is an insulator, between a positive electrode  11  and a negative electrode  12 , a case  34  that houses the electrode assembly  10 , and a cap assembly  20  that is coupled to an opening of the case  34 . 
     The rechargeable battery  100  according to the present exemplary embodiment is a lithium ion rechargeable battery and has a quadrangular shape. However, the present invention is not limited thereto, and the present invention can be applied to various forms of batteries such as a lithium polymer battery or a cylindrical battery. 
     The positive electrode  11  and the negative electrode  12  each include a coating region, which is a region that is coated with an active material, and uncoated regions  11   a  and  12   a , which are regions that are not coated with an active material, in a current collector that is formed with a thin plate of metal foil. The positive uncoated region  11   a  is formed at one side end of the positive electrode  11  along a length direction of the positive electrode  11 , and the negative uncoated region  12   a  is formed at the other side end of the negative electrode  12  along a length direction of the negative electrode  12 . The positive electrode  11  and the negative electrode  12  are spiral-wound with a separator  13 , which is an insulator, located therebetween. 
     However, the present invention is not limited thereto, and the electrode assembly  10  may be formed in a structure in which a positive electrode and a negative electrode that are formed with a plurality of sheets are alternately stacked with a separator located therebetween. 
     The case  34  forms substantially an entire external portion of the rechargeable battery  100  and is formed with a conductive metal such as aluminum, aluminum alloy or nickel-plated steel. Further, the case  34  provides a space that houses the electrode assembly  10 . For example, the case  34  may be formed in a cuboid quadrangular shape having an opening at one side thereof in order to house a substantially cuboid electrode assembly  10 . The opening faces upward in the case  34  shown in  FIGS. 1 and 2 . 
     The cap assembly  20  includes a cap plate  30  that covers the opening of the case  34 , a positive terminal  21  that protrudes to the outside of the cap plate  30  and that is electrically connected to the positive electrode  11 , and a negative terminal  22  that is electrically connected to the negative electrode  12 . 
     The cap plate  30  is formed as a thin plate and is coupled to the opening of the case  34 . A seal stopper  38  is installed in an electrolyte injection opening  31  of the cap plate  30 , and a vent member  39  having a notch  39   a  adapted to fracture at a threshold pressure is installed in a vent hole  32 . 
     The positive terminal  21  and the negative terminal  22  penetrate through the cap plate  30 , and flanges  21   a  and  22   a  that are supported in a lower part of the cap plate  30  are formed in lower parts of the positive terminal  21  and the negative terminal  22  respectively. A thread is formed on an external circumferential surface of the positive and negative terminals  21 ,  22  that protrude to the outside of the cap plate  30 . Further, a nut  29  that supports an upper part of the positive and negative terminals is fastened to the terminals  21  and  22 . A washer  24  that buffs a fastening force of the nut  29  is installed in a lower part of the nut  29  between the nut end and the cap plate  30 . 
     In the present exemplary embodiment, the terminals  21  and  22  are fixed through the nut  29 . However the present invention is not limited thereto, and the terminals  21  and  22  may be formed in a rivet structure or fixed by welding. 
     A lower gasket  27  and an upper gasket  25  are installed between each of the terminals  21  and  22  and the cap plate  30 , the lower gasket  27  being positioned between the flanges  21   a  and  22   a  and the cap plate  30 , and the upper gasket  25  being positioned between the cap plate  30  and the washer  24 . 
     The positive terminal  21  includes a positive lead tab  50  that is bonded to a positive uncoated region  11   a  by welding, and the negative terminal  22  includes a negative lead tab  40  that is bonded to a negative uncoated region  12   a  by welding. Lower protrusions  21   b  and  22   b  are formed in a lower part of the flanges  21   a  and  22   a , and the lead tabs  40  and  50  are fixed to the lower protrusions  21   b  and  22   b  by welding. However, the present invention is not limited thereto and a terminal and a lead tab may be integrally formed. 
     A lower insulation member  26  is installed between the terminals  21  and  22  and the cap plate  30 , and an upper end of the lead members  40  and  50  and the flanges  21   a  and  22   a  of the terminals  21  and  22  are inserted into a groove that is formed in the lower insulation member  26 . 
       FIG. 3  is an exploded perspective view illustrating a lead tab and an anti-vibration member according to a first exemplary embodiment of the present invention. 
     Referring to  FIGS. 2 and 3 , the lead tab and the anti-vibration member are described in detail. 
     Because the negative lead tab  40  has substantially the same structure as that of the positive lead tab  50 , only the positive lead tab  50  will be described in detail. 
     The positive lead tab  50  includes a terminal junction part  51  in which a terminal hole  51   a  adapted to receive the lower protrusion  21   b  is formed, a side plate  52  extending from the terminal junction part  51  and positioned between a side section of the electrode assembly  10  and the case  34 , and an electrode assembly junction part  53  extending from the side plate  52  and attached to the positive uncoated region  11   a  by welding. The side plate  52  is bent orthogonally from the terminal junction part  51 . 
     A vent hole  54  that moves a gas generated within the electrode assembly  10  to an upper part of the case  34  is formed in the side plate  52 . Two electrode assembly junction parts  53  are formed extending from the side plate  52  and are bent from the side plate  52  to be parallel to a wide surface of the uncoated regions  11   a  and  12   a.    
     The electrode assembly junction part  53  is formed toward the bottom of the case  34  from both side ends of the side plate  52  and is attached to both side surfaces of the positive uncoated region  11   a  by ultrasonic welding. 
     A structure of the positive lead tab  50  is an exemplary illustration, but the present invention is not limited thereto. The positive lead tab  50  is formed to electrically connect a terminal and an electrode assembly. 
     An anti-vibration member hole (or spacer opening)  56  is formed in the side plate  52 , the anti-vibration member hole  56  being disposed at a lower part of the vent hole  54 , and an anti-vibration member (or spacer)  60  is inserted into the anti-vibration member hole  56 . The anti-vibration member  60  is made of a polymer having elasticity in order to absorb an external impact. 
     The anti-vibration member  60  includes a first support part  65  that is positioned between the side plate  52  and an inner surface of the case  34 , a second support part  61  that passes through the anti-vibration member hole  56  and that supports the first support part  65  in a surface opposite to a surface at which the first support part  65  is positioned, and a connecting bar  62  that connects the first support part  65  and the second support part  61  and that is inserted into the anti-vibration member hole  56 . In this case, the second support part  61  is positioned between the side plate  52  and the electrode assembly  10 . 
     The first support part  65  is formed in an approximately circular cylinder shape and closely contacts the side plate  52  and an inner surface of the case  34 . The first support part  65  is inserted by tight fit between the side plate  52  and the case  34  in order to stably support the electrode assembly  10  and the terminal  21 . 
     The second support part  61  is formed in a truncated circular cone shape such that a cross-section area of one side end thereof is formed smaller than that of an area of the anti-vibration member hole  56 , and a cross-section area of a portion contacting with the connecting bar  62  is formed greater than that of an area of the anti-vibration member hole  56 . Accordingly, an edge of the second support part  61  functions as a latch jaw, and the second support part  61  easily passes through the anti-vibration member hole  56  and stably supports the anti-vibration member  60  at one side thereof. 
     When the second support part  61  is supported between the electrode assembly  10  and the side plate  52  and the first support part  65  is supported between the side plate  52  and the case  34 , the anti-vibration member  60  is stably fixed to the side plate  52 . A spacer that is simply installed between the positive lead tab  50  and the case  34  and the anti-vibration member  60  according to the present exemplary embodiment are completely different in a structure and a function. Even if the spacer is installed, the electrode assembly  10  and the terminals  21  and  22  may be shaken at a minute vibration or impact. However, when the anti-vibration member  60  is stably fixed to the side plate  52  and the second support part  61  is tightly fit between the side plate  52  and an inner side surface of the case  34 , the electrode assembly  10  and the terminals  21  and  22  are stably supported. 
     The connecting bar  62  is formed in a circular bar shape. However, the connecting bar  62  may also be formed in various structures such as a triangular bar and a quadrangular bar according to a shape of the anti-vibration member hole  56 . 
     As in the present exemplary embodiment, if the anti-vibration member  60  is installed in the positive lead tab  50  and the negative lead tab  40 , the anti-vibration member  60  supports the terminals  21  and  22 , respectively, and the electrode assembly  10  at both side ends of the electrode assembly  10 , and thus the terminals  21  and  22  or the electrode assembly  10  can be prevented from being dislodged or moved with respect to the case by an external impact or vibration. Accordingly, an electrical contact between the terminals  21  and  22  and the electrode assembly  10  can be stably maintained and the lead tabs  40  and  50  can be prevented from being deformed. 
       FIG. 4  is an exploded perspective view illustrating a lead tab and an anti-vibration member according to a second exemplary embodiment of the present invention. 
     Referring to  FIG. 4 , a lead tab  70  according to the present exemplary embodiment includes a terminal junction part  71  in which a terminal hole  71   a  adapted to receive a lower protrusion  21   b  is formed, a side plate  72  extending from a lower part of the terminal junction part  71  and positioned between a side section of an electrode assembly  10  and a case  34 , and an electrode assembly junction part  73  extending from the side plate  72  and that is attached to a positive uncoated region by welding. 
     A vent hole  74  adapted to discharge a gas and a plurality of anti-vibration holes  76  each adapted to receive an anti-vibration member  80  are formed in the side plate  72 . In the present exemplary embodiment, four anti-vibration holes  76  are formed in the side plate  72 , and four anti-vibration members  80  are installed in the side plate  72 . However, the present invention is not limited thereto and more or fewer than four anti-vibration holes  76  may be formed. 
     The anti-vibration member  80  is made of a polymer having elasticity in order to absorb an external impact. The anti-vibration member  80  includes a first support part  85  positioned between the side plate  72  and an inner surface of the case  34 , a second support part  81  that passes through the anti-vibration hole  76  and that supports the first support part  85  on a surface opposite to a surface on which the first support part  85  is positioned, and a connecting bar  82  that connects the first support part  85  and the second support part  81  and that is inserted into the anti-vibration hole  76 . 
     As in the present exemplary embodiment, when a plurality of anti-vibration members  80  are installed in the side plate  72 , an impact is absorbed at a plurality of locations and thus durability against an impact and vibration is further improved. Further, when the anti-vibration member  80  is tightly fit between the lead tab  70  and the case  34 , the anti-vibration member  80  supports the electrode assembly  10  and the terminals  21  and  22  in all directions by a friction force. 
       FIG. 5  is an exploded perspective view illustrating a lead tab and an anti-vibration member according to a third exemplary embodiment of the present invention, and  FIG. 6  is a vertical cross-sectional view illustrating a coupled state of members that are shown in  FIG. 5 . 
     Referring to  FIGS. 5 and 6 , a lead tab  120  according to the present exemplary embodiment includes a terminal junction part  121  in which a terminal hole  121   a  adapted to receive a lower protrusion  21   b  is formed, a side plate  122  that is formed extending from the terminal junction part  121  and that is positioned between a side section of an electrode assembly  10  and a case  34 , and an electrode assembly junction part  123  extending from the side plate  122  and that is attached to a positive uncoated region by welding. 
     A vent hole  124  adapted to discharge a gas and a plurality of anti-vibration holes  126  each adapted to receive an anti-vibration member  130  are formed in the side plate  122 . 
     The anti-vibration member  130  is made of a polymer having elasticity in order to absorb an external impact. The anti-vibration member  130  includes a base plate  131 , a first support part  135  that protrudes toward the case  34  from the base plate  131 , a second support part  134  that passes through the anti-vibration hole  126  and that is positioned between the side plate  122  and the electrode assembly  10 , and a connecting bar  136  that is positioned between the base plate  131  and the second support part  134  and that is inserted into the anti-vibration hole  126 . 
     Further, an exhaust groove  132  that easily discharges a gas in a portion corresponding to the vent hole  124  is formed in the anti-vibration member  130 . The exhaust groove  132  extends centrally from an upper end of the anti-vibration member  130  to allow a gas that is discharged through the vent hole  124  to easily move to an upper part of the case  34 . 
     The first support part  135  is formed in an approximately circular cylindrical shape and protrudes toward an inner side wall of the case  34  from the base plate  131 . In one embodiment, a plurality of first support parts  135  are formed in the base plate  131 , and the first support part  135  is formed in an upper part of the base plate  131  and is formed in a lower part of a surface that is parallel to a side wall of the case  34  and has an inclined surface  135   a  that has a reduced height as advancing toward an end portion from the center thereof, i.e. the inclined surface generally faces toward the bottom of the case  34 . 
     When the inclined surface  135   a  is formed in this way, when the anti-vibration member  130  is installed in the lead tab  120 , when the lead tab is inserted into the case  34 , the anti-vibration member  130  can be easily inserted even when a tight fit is formed with an inner side wall of the case  34 . 
     The second support part  134  is formed in an approximately truncated circular cone shape and an edge thereof is latched at one side of the side plate  122  to support the anti-vibration member  130 . The second support parts  134  are formed with the same number as that of the anti-vibration holes  126  to pass through the anti-vibration hole  126 . 
     As in the present exemplary embodiment, when a plurality of first support parts  135  and second support parts  134  are formed in the base plate  131 , the anti-vibration member  130  is easily installed, and a plurality of second support parts  134  absorb vibration and impact, and thus durability against impact and vibration is improved. 
       FIG. 7  is an exploded perspective view illustrating a lead tab and an anti-vibration member according to a fourth exemplary embodiment of the present invention, and  FIG. 8  is a transverse cross-sectional view illustrating a coupled state of members that are shown in  FIG. 6 . 
     Referring to  FIGS. 7 and 8 , a lead tab  140  according to the present invention exemplary embodiment includes a terminal junction part  141  in which a terminal hole  141   a  adapted to receive a lower protrusion  21   b  is formed, a side plate  142  extending from the terminal junction part  141  and positioned between a side section of the electrode assembly  10  and the case  34 , and an electrode assembly junction part  143  extending from the side plate  142  and attached to a positive uncoated region by welding. 
     A vent hole  144  adapted to discharge a gas and an anti-vibration groove  146  adapted to receive an anti-vibration member  150  are formed in the side plate  142 . The anti-vibration grooves  146  are formed along both side edges of the side plate  142  and have a structure that is cut toward the center from the side edges. 
     The anti-vibration member  150  is made of a polymer having elasticity in order to absorb an external impact. The anti-vibration member  150  includes a base plate  151 , a first support part  155  that protrudes toward the case  34  from the base plate  151 , a second support part  154  that passes through the anti-vibration groove  146  and supported between the side plate  142  and the electrode assembly  10 , and a connecting bar  152  positioned between the base plate  151  and the second support part  154  and inserted into the anti-vibration groove  146 . 
     In the present exemplary embodiment, the anti-vibration groove  146  is formed in the side plate  142 , and the second support part  154  is installed through the anti-vibration groove  146 . However, the present invention is not limited thereto, and the anti-vibration groove  146  does not have to be formed in the side plate  142 . Rather, the second support part  154  may be installed on both side edges of the side plate  142  and may be supported by the side edges without the need for the anti-vibration grooves  146 . 
     The first support part  155  is formed in an approximately circular cylindrical shape and protrudes toward an inner side wall of the case  34  from the base plate  151 . A plurality of first support parts  155  are formed in the base plate  151 , and an end portion of each first support part  155  is formed parallel to a side wall of the case  34 . 
     The second support part  154  is formed in a wedge shape and has a latch jaw  154   a  at one side thereof. Accordingly, the second support part  154  can stably support the anti-vibration member  150  against a surface of the side plate  142  advancing toward a direction opposite to that of a surface against which the base plate  151  is positioned. 
     While this disclosure has been described in connection with what is presently considered to be practical exemplary 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.