Abstract:
A rechargeable battery is provided including an electrode assembly including a positive electrode and a negative electrode; a case accommodating the electrode assembly; a cap plate coupled to the case; a first terminal and a second terminal electrically connected to the electrode assembly and protruding outside the cap plate; and a short-circuit member at the cap plate and contacting the first terminal by transformation to induce a short.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2013-0041733 filed in the Korean Intellectual Property Office on Apr. 16, 2013, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to a rechargeable battery 
         [0004]    2. Description of the Related Art 
         [0005]    A rechargeable battery differs from a primary battery in that it can be repeatedly charged and discharged, while the latter only irreversibly converts chemical energy to electrical energy. A low-capacity rechargeable battery is used as a power supply for small electronic devices, such as cellular phones, notebook computers, and camcorders, while a high-capacity rechargeable battery is used as a power supply for driving motors in hybrid vehicles and the like. 
         [0006]    A high-power rechargeable battery using a non-aqueous electrolyte with high energy density has been recently developed. For example, the high-power rechargeable battery is constructed with a plurality of rechargeable cells coupled to each other in series such that it can be used as a power supply for driving motors in electric vehicles requiring a high amount of power. 
         [0007]    Furthermore, one high-capacity rechargeable battery is commonly formed with a plurality of rechargeable cells coupled to each other in series. The rechargeable battery may have a cylindrical shape or a prismatic shape. When the internal pressure of the rechargeable battery is increased, a chance of explosion increases. Some batteries include a structure to induce an external short to prevent an explosion, but to induce the external short, the number of related components is increased and an assembly process is complicated. 
         [0008]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention 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 
       [0009]    Embodiments of the present invention provides a rechargeable battery with an improved assembly characteristic and improved safety. 
         [0010]    A rechargeable battery according to the present invention includes: an electrode assembly including a positive electrode and a negative electrode; a case having a space receiving the electrode assembly; a cap plate coupled to the case; a first terminal and a second terminal electrically connected to the electrode assembly and protruding outside the cap plate; and a short-circuit member installed at the cap plate and contacting the first terminal by transformation to induce a short. 
         [0011]    The first terminal may include an upper connection part separated from the short-circuit member and positioned on the short-circuit member, a current collecting connection part connected to the electrode assembly, and a middle connection part formed between the upper connection part and the current collecting connection part and bent from the upper connection part and the current collecting connection part. 
         [0012]    The upper connection part and the current collecting connection part may be oriented substantially parallel to the cap plate, and a sealing member sealing between the first terminal and the cap plate may be formed at the first terminal to partially enclose the terminal. 
         [0013]    The sealing member may be formed by insert injection, and the sealing member may include an upper sealing part mounted on the cap plate and a lower sealing part inserted and fixed to a terminal hole formed at the cap plate. 
         [0014]    The lower sealing part may include a hole in which the middle connection part is inserted, and a groove connected to the hole and receiving a current collecting connection part may be formed at a lower surface of the lower sealing part. 
         [0015]    A protrusion may be formed inside the terminal hole, a sealing groove receiving the protrusion may be formed at the circumference of the lower sealing part, the protrusion may be extended according to a circumference direction from an interior circumference of the terminal hole, and the sealing groove may be extended according to a circumference of the lower sealing part. 
         [0016]    The current collecting connection part may be connected to the electrode assembly through a current collecting member, and a protrusion inserted into the current collecting member may be formed at the lower surface of the current collecting connection part. 
         [0017]    The short-circuit member may include a supporting part separated from the upper connection part, installed to face the lower surface of the upper connection part, and fixed to the cap plate, and a connector positioned inside the supporting part and curved downward to convexly protrude. 
         [0018]    The short-circuit member may be integrally formed with the cap plate and have a thinner thickness than other portions of the cap plate, and is convexly curved downward, and a connection member electrically connecting the second terminal to the cap plate may be formed between the second terminal and the cap plate. 
         [0019]    The current collecting member may be coupled to the electrode assembly by welding, the cap plate may include a protrusion inserted into the current collecting member, and the second terminal may include a middle connection part integrally formed with the cap plate and protruding at the upper surface of the cap plate and an upper connection part bent from the middle connection part. 
         [0020]    The second terminal may include a lower connection part fixed to the upper surface of the cap plate by welding, a middle connection part bent from the lower connection part to protrude upward, and an upper connection part bent from the middle connection part and oriented substantially parallel to the cap plate. 
         [0021]    According to an exemplary embodiment of the present invention, the terminal may directly contact the short-circuit member such that the assembly characteristic may be improved, and the sealing member is installed at the cap plate and the terminal by insert molding such that the process may be simplified. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1  is a perspective view of a rechargeable battery according to a first exemplary embodiment of the present invention. 
           [0023]      FIG. 2  is a cross-sectional view taken along the line II-II of  FIG. 1 . 
           [0024]      FIG. 3  is a perspective view of a terminal according to the first exemplary embodiment of the present invention. 
           [0025]      FIG. 4  is an exploded perspective view of a cap plate and a sealing member according to the first exemplary embodiment of the present invention. 
           [0026]      FIG. 5  is a cross-sectional view of a terminal and a cap plate according to the first exemplary embodiment of the present invention. 
           [0027]      FIG. 6  is a cross-sectional view of a rechargeable battery according to a second exemplary embodiment of the present invention. 
           [0028]      FIG. 7  is a cut-away perspective view of a terminal and a cap plate according to the second exemplary embodiment of the present invention. 
           [0029]      FIG. 8  is a cut-away perspective view of a terminal and a cap plate according to the second exemplary embodiment of the present invention. 
           [0030]      FIG. 9  is a cut-away perspective view of a terminal and a cap plate according to a third exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    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. Like reference numerals designate like elements throughout the specification. 
         [0032]      FIG. 1  is a perspective view of a rechargeable battery according to the first exemplary embodiment of the present invention, and  FIG. 2  is a cross-sectional view taken along the line II-II of  FIG. 1 . 
         [0033]    Referring to  FIG. 1  and  FIG. 2 , a rechargeable battery  101  according to the first exemplary embodiment includes an electrode assembly  10  where a negative electrode (e.g., a first electrode)  11  and a positive electrode (e.g., a second electrode)  12  are wound with an insulating separator  13  therebetween, a case  26  mounting the electrode assembly  10  therein, and a cap assembly  30  coupled to an opening of the case  26 . 
         [0034]    The rechargeable battery  101  according to the first exemplary embodiment of the present invention is a lithium ion rechargeable battery which has an angular shape, and will be described as an example. However, the present invention is not limited thereto, and the present invention may be applied to batteries such as a lithium polymer battery, a cylindrical battery, and the like. 
         [0035]    The positive electrode  11  and the negative electrode  12  include a coating region where an active material is coated on a current collector formed of a thin-film metal foil, and an uncoated region in which the active material is not coated. 
         [0036]    A negative electrode uncoated region  11  a is formed at a side end of the other side of the negative electrode  11  along a length direction of the negative electrode  11 , and a positive electrode uncoated region  12   a  is formed at a side end of one side of the positive electrode  12  along a length direction of the positive electrode  12 . In addition, the negative electrode  11  and the positive electrode  12  are spiral-wound after inserting the separator  13  that is an insulator therebetween. 
         [0037]    However, the present invention is not limited thereto, and the electrode assembly  10  may have other structures, for example, wherein the positive electrode and the negative electrode including a plurality of sheets are laminated with an insulator located therebetween. 
         [0038]    The case  26  is formed as an approximate cuboid, and an opening is formed on a side thereof. The cap assembly  30  includes a cap plate  31  covering the opening of the case  26 , a first terminal  21  on the cap plate  31  and electrically connected to the negative electrode  11 , a second terminal  22  on the cap plate  31  and electrically connected to the positive electrode  12 , and a vent member  39  having a notch  39   a  formed to be fractured according to a predetermined internal pressure. The vent member  39  is installed in a vent hole  34  formed at the cap plate  31 . 
         [0039]    The cap plate  31  is formed of a thin metal plate, and a sealing cap  38  sealing an electrolyte injection opening  37  formed at one side thereof is fixed and installed at the cap plate  31 . A short-circuit hole  32  is formed at the cap plate  31 , and a short-circuit member  35  is installed at the short-circuit hole  32 . The short-circuit member  35  is formed in the shape of a circular plate, and includes a supporting part  35   a  and a connector  35   b  positioned inside the supporting part  35   a . The supporting part  35   a  is formed in a ring shape and is supported by a step protruding inside the short-circuit hole  32  to be fixed on the upper surface of the cap plate  31  by welding. The connector  35   b  is curved downward toward the case and electrolyte assembly to have a cross-section of an arc shape that convexly protrudes generally in a direction toward the electrode assembly  10 . When the internal pressure of the case  26  is increased, the short-circuit member  35  is transformed to protrude in substantially the opposite direction and to contact the first terminal  21  thereby generating the short. 
         [0040]    The first terminal  21  and the second terminal  22  are installed to penetrate terminal holes H 1  and H 2  formed at the cap plate  31 , and are electrically connected to the electrode assembly  10 . That is, the first terminal  21  is installed to be electrically connected to the negative electrode  11 , and in this case, the first terminal  21  is electrically connected to the negative electrode  11  through a current collecting member  25 . A sealing member  40  enclosing the first terminal  21  is installed at the first terminal  21 . 
         [0041]    The second terminal  22  is installed to be electrically connected to the positive electrode  12 , and in this case, the second terminal  22  is electrically connected to the positive electrode  12  through a current collecting member  27 . A sealing member  50  enclosing a portion of the second terminal  22  is installed at the second terminal  22 . 
         [0042]      FIG. 3  is a perspective view of the first terminal  21  according to the first exemplary embodiment of the present invention, and  FIG. 4  is an exploded perspective view of the cap plate  31  and the sealing member  21  according to the first exemplary embodiment of the present invention. 
         [0043]    Referring to  FIG. 3  and  FIG. 4 , the second terminal  22  and members connected thereto are symmetrical with the first terminal  21  and members connected thereto such that the description of the first terminal  21  and the members connected thereto equates to the description of the second terminal  22 . 
         [0044]    The first terminal  21  is formed of a plate shape and includes an upper connection part  21   a  positioned on the cap plate  31 , a current collecting connection part  21   b  inserted inside the case  26  and coupled to the current collecting member  25 , and a middle connection part  21   c  formed between the upper connection part  21   a  and the current collecting connection part  21   b  and bent at the upper connection part  21   a  and the current collecting connection part  21   b.    
         [0045]    The upper connection part  21   a  is oriented substantially parallel to the cap plate  31  on the cap plate  31 , and is separated from the short-circuit member  35  to be positioned on the short-circuit member  35 . 
         [0046]    The current collecting connection part  21   b  is oriented substantially parallel to the cap plate  31  under the cap plate  31 , and a protrusion  21   d  inserted into the current collecting member  25  to be coupled to the current collecting member  25  by welding is formed at the bottom surface of the current collecting connection part  21   b.    
         [0047]    The middle connection part  21   c  is curved substantially at a right angle at the upper connection part  21   a  and the current collecting connection part  21   b  to connect the upper connection part  21   a  and the current collecting connection part  21   b  and is inserted into a hole  43  formed at the sealing member  40 . Also, the middle connection part  21   c  penetrates the cap plate  31  to connect the upper connection part  21   a  located outside of the case  26  and the current collecting connection part  21   b  located inside the case  26 . 
         [0048]    The upper connection part  21   a  and the current collecting connection part  21   b  are oriented substantially parallel to the cap plate  31 , and the middle connection part  21   c  is oriented substantially perpendicular to the upper connection part  21   a  and the current collecting connection part  21   b.    
         [0049]    The sealing member  40  includes an upper sealing part  41  mounted on the cap plate  31  and a lower sealing part  42  inserted into and fixed to the terminal hole H 1  formed at the cap plate  31 . The upper sealing part  41  contacts the side surface of the middle connection part  21   c  and the bottom surface of the upper connection part  21   a  such that the upper connection part  21   a  is supported to be separated from the cap plate. 
         [0050]    The lower sealing part  42  includes the hole  43  in which the middle connection part  21   c  is inserted, and a mounting groove  49  connected to the hole  43  and inserted with the current collecting connection part  21   b  is formed at the bottom surface. The hole  43  is formed to penetrate the cap plate. 
         [0051]    Also, a sealing groove  46  receiving a protrusion  31   b  protruding to the inside from the terminal hole H 1  is formed at the circumference of the lower sealing part  42 . The protrusion  31   b  is extended according to the circumference direction at the interior circumference of the terminal hole H 1 , and the sealing groove  46  is extended according to the circumference of the lower sealing part  42  to receive the protrusion  31   b . Also, a supporting groove  31   a  mounted with the side upper end of the lower sealing part is formed on the protrusion  31   b . Accordingly, the sealing member  40  may be stably fixed to the cap plate  31 . 
         [0052]    When the first terminal  21  is installed on the cap plate  31 , the sealing member  40  is formed by an insert molding method. Accordingly, the sealing member  40  is formed and simultaneously is fixed and installed to the cap plate  31 , thereby being fixed on the cap plate  31  while enclosing the first terminal  21 . 
         [0053]    Like the first terminal  21 , the second terminal  22  includes an upper connection part positioned on the cap plate  31 , a current collecting connection part inserted inside the case  26  and coupled to the current collecting member  27 , and a middle connection part formed between the upper connection part and the current collecting connection part and bent at the upper connection part and the current collecting connection part. Also, the sealing member  50  inserted into the terminal hole H 2  and supporting the second terminal  22  is installed at the second terminal  22 . The sealing member  50  is formed through an insert molding when the second terminal is installed at the cap plate. 
         [0054]    A connection member  28  electrically connecting the second terminal  22  to the cap plate  31  is installed between the upper surface of the cap plate  31  and the second terminal  22 . The connection member  28  is made of a metal such as copper, and is fixed to the second terminal  22  and the cap plate  31  by welding. Accordingly, the cap plate  31  and the case  26  are connected to the positive electrode. 
         [0055]    As shown in  FIG. 5 , if the internal pressure of the rechargeable battery  101  is increased, the short-circuit member  35  is deformed to be convex upward, i.e., extending substantially away from the electrode assembly  10 . Accordingly, the bottom surface of the first terminal  21  and the upper surface of the short-circuit member  35  electrically contact each other such that the first terminal  21  connected to the negative electrode and the short-circuit member  35  connected to the positive electrode are shorted. Like the present exemplary embodiment, if the short is generated when the pressure is increased, the charges that are cumulated inside are instantaneously discharged such that the chance of explosion may be reduced. 
         [0056]    Further, the short-circuit member  35  directly contacts the first terminal  21  such that the short may be easily generated even though a tab for the short-circuit is not installed or present. Also, the sealing members  40  and  50  are installed to the first terminal  21  and the second terminal  22 , respectively, by an insert molding method such that the first terminal  21  and the second terminal  22  are easily installed. 
         [0057]      FIG. 6  is a cross-sectional view of a rechargeable battery according to the second exemplary embodiment of the present invention,  FIG. 7  is a cut-away perspective view of a terminal and a cap plate according to the second exemplary embodiment of the present invention, and  FIG. 8  is a cut-away perspective view of a terminal and a cap plate according to the second exemplary embodiment of the present invention. 
         [0058]    Referring to  FIG. 6  to  FIG. 8 , the rechargeable battery according to the present exemplary embodiment is the same as the rechargeable battery according to the first exemplary embodiment except for the cap plate and the second terminal such that the overlapping description is omitted. 
         [0059]    The first terminal  21  electrically connected to the negative electrode  11  is fixed and installed at a cap plate  60  through the sealing member  40 , and the second terminal  62  electrically connected to the positive electrode  12  is formed at the cap plate  60 . The first terminal  21  is positioned on a short-circuit member  61  formed at the cap plate  60  and is oriented to be separated from the short-circuit member. The short-circuit member  61  is integrally formed with the cap plate  60  such that the short-circuit member  61  is thinner than a remainder of the cap plate  60  and is made of a structure that is curved to be convex downward, i.e., the short circuit member extends generally towards the electrode assembly  10 . Like the present exemplary embodiment, the short-circuit member  61  is integrally formed with the cap plate  60 , so it is not necessary to additionally form the short-circuit member  61 , thereby simplifying an assembly process. 
         [0060]    The second terminal  62  includes a middle connection part  62   a  protruding from the upper surface of the cap plate  60  and extending upward, and an upper connection part  62   b  bent from the middle connection part  62   a . The second terminal  62  is formed with the plate shape that is integrally formed with the cap plate  60 , and the middle connection part  62   a  protrudes perpendicular to the upper surface of the cap plate  60 . The upper connection part  62   b  is bent from the middle connection part  62   a  to be oriented substantially parallel to the upper surface of the cap plate  60  at the upper surface of the cap plate  60 . 
         [0061]    Additionally, the current collecting member  27  electrically connected to the positive electrode  12  is adhered to the cap plate  60  by welding. A protrusion  63  close to the current collecting member  27  is formed at the lower surface of the cap plate  60 , and the current collecting member  27  is fixed to the cap plate  60  by welding such that the current collecting member  27  is inserted over the protrusion  63  which protrudes into the current collecting member. Accordingly, the cap plate  60  is electrically connected to the positive electrode  12  and the second terminal  62  is electrically connected to the positive electrode  12  through the cap plate  60 . 
         [0062]    As described above, according to the present exemplary embodiment, the second terminal  62  is integrally formed with the cap plate  60  such that it is not necessary to seal between the second terminal  62  and the cap plate  60  and the contact resistance between the second terminal  62  and the cap plate  60  may be reduced. 
         [0063]      FIG. 9  is a cut-away perspective view of a terminal and a cap plate according to the third exemplary embodiment of the present invention. 
         [0064]    Referring to  FIG. 9 , the rechargeable battery according to the present exemplary embodiment is the same as the rechargeable battery according to the second exemplary embodiment except for the second terminal such that the overlapping description is omitted. 
         [0065]    In one embodiment, the second terminal  72  electrically connected to the positive electrode  12  is formed at a cap plate  70 . The second terminal  72  includes a lower connection part  72   a  fixed to the upper surface of the cap plate  70  by welding, a middle connection part  72   c  bent from the lower connection part and protruding upward, and an upper connection part  72   b  bent from the middle connection part  72   c . The lower connection part  72   a  is oriented substantially parallel to the cap plate  70  and is fixed to the upper surface of the cap plate  70  by welding. The middle connection part  72   c  is bent perpendicular from the lower connection part  72   a  to protrude upward. The upper connection part  72   b  is bent perpendicular from the middle connection part  72   c  to be oriented substantially parallel to the upper surface of the cap plate  70 . 
         [0066]    A protrusion  73  electrically connected to the positive electrode  12  and coupled to the current collecting member  27  is formed at the lower surface of the cap plate  70 . Accordingly, the cap plate  70  is electrically connected to the positive electrode  12 , and the second terminal  72  is electrically connected to the positive electrode  12  through the cap plate  70 . 
         [0067]    As described above, according to the present exemplary embodiment, the second terminal  72  is fixed to the upper surface of the cap plate  70  by welding such that the cap plate  70  does not need the hole in which the second terminal  72  is inserted, and thereby it is not necessary to seal between the second terminal  72  and the cap plate  70 . 
         [0068]    While this invention 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. 
       DESCRIPTION OF SYMBOLS 
       [0069]      
         [0000]    
       
         
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
               
             
               
             
           
               
                   
               
             
             
               
                 101, 102: rechargeable battery 
                 10: electrode assembly 
               
               
                 11: negative electrode 
                 11a: negative uncoated region 
               
             
          
           
               
                 12: positive electrode 
                 12a: positive electrode uncoated region 
               
             
          
           
               
                 13: separator 
                 21: first terminal 
               
             
          
           
               
                 21a: upper connection part 
                 21b: current collecting connection part 
               
               
                 21c: middle connection part 
                 21d: protrusion 
               
               
                 22, 62, 72: second terminal 
                 25, 27: current collecting member 
               
             
          
           
               
                 26: case 
                 28: connection member 
               
               
                 30: cap assembly 
                 31, 60, 70: cap plate 
               
             
          
           
               
                 31a: supporting groove 
                 31b: protrusion 
               
             
          
           
               
                 35, 61: short-circuit member 
                 35a: supporting part 
               
             
          
           
               
                 35b: connector 
                 40, 50: sealing member 
               
               
                 41: upper sealing part 
                 42: lower sealing part 
               
             
          
           
               
                 43: hole 
                 46: sealing groove 
               
             
          
           
               
                 49: mounting groove