Abstract:
A rechargeable battery configured to prevent or substantially prevent explosion resulting from overheating. In one embodiment, a rechargeable battery includes: a first metallic plate; a second metallic plate coupled to the first metallic plate to together include five sides of a hexahedron and define a cavity and an opening to the cavity being a sixth side of the hexahedron, at least one of the first metallic plate or the second metallic plate including a base and walls extending from at least two opposing peripheral sides of the base; a generation member in the cavity and including at least one connection member at a side of the generation member proximate the opening; and a cap assembly including an insulator and at least one electrode lead coupled to the at least one connection member, the cap assembly closing the opening.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/166,568 filed on Apr. 3, 2009, the entire content of which is incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present invention relates to a rechargeable battery, and more particularly to a rechargeable battery configured to prevent or substantially prevent explosion resulting from overheating, and having a reduced manufacturing cost. 
         [0004]    2. Description of the Related Art 
         [0005]    A rechargeable battery can be repeatedly charged and discharged, unlike a primary battery which cannot be recharged. A low-capacity rechargeable battery is used for portable small-sized electronic devices, such as mobile phones, notebook computers, and camcorders. A large-capacity battery is widely used as a power source for driving motors, such as for hybrid vehicles. 
         [0006]    One type of rechargeable battery is a rechargeable battery using a pouch method of coating polypropylene on an aluminum material in order to close and seal the outside of a generation element. However, the pouch method used by the rechargeable battery has a limit to the molding of the external shape of a pouch because of deformation of aluminum and polypropylene. Accordingly, it is difficult to form a pouch with a thickness of 6 to 7 mm or more. Further, the aluminum material is problematic in that the manufacturing cost is increased because the price of aluminum is relatively high. The aluminum material is also problematic in that it has a danger of explosion when abnormal overheating occurs within a rechargeable battery. 
         [0007]    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 
       [0008]    Embodiments of the present invention provide a rechargeable battery having a reduced manufacturing cost, a large thickness, being formed of a metal other than aluminum, and having metal portions thereof closed or coupled by laser welding. Further, embodiments of the present invention provide a rechargeable battery configured to prevent or substantially prevent explosion resulting from overheating of the rechargeable battery. 
         [0009]    According to one exemplary embodiment of the present invention, a rechargeable battery includes: a first metallic plate; a second metallic plate coupled to the first metallic plate to together include five sides of a hexahedron and define a cavity and an opening to the cavity being a sixth side of the hexahedron, at least one of the first metallic plate or the second metallic plate including a base and walls extending from at least two opposing peripheral sides of the base; a generation member in the cavity and including at least one connection member at a side of the generation member proximate the opening; and a cap assembly including an insulator and at least one electrode lead coupled to the at least one connection member, the cap assembly closing the opening. 
         [0010]    The first and second metallic plates may include steel, stainless steel, or a metal other than aluminum. 
         [0011]    The at least one of the first metallic plate or the second metallic plate may include flange portions protruding from respective ones of the walls in at least one direction substantially parallel to a surface of the base. The first and second metallic plates may be fixed to each other at the flange portions via welding or via crimping. 
         [0012]    The at least one electrode lead may be mounted on the insulator. The at least one electrode lead may include a plurality of protruding portions, and the insulator may have a plurality of openings receiving the plurality of protruding portions for mounting the at least one electrode lead on the insulator. The insulator may have at least one groove defining at least one recessed surface, the at least one recessed surface contacting the at least one electrode lead and having the plurality of openings therein. 
         [0013]    The insulator may be pressed into the opening. The insulator may have at least one side that is tapered along a direction extending toward the cavity. The at least one tapered side of the insulator may be tapered at an angle between about 1 degree and about 10 degrees. The at least one tapered side of the insulator may include two opposing tapered sides. 
         [0014]    The cap assembly may be fixed to the first and second metallic plates via at least partial melting of the insulator. The first and second metallic plates may be fixed to each other via a welding process, and the insulator may be at least partially melted via heat from the welding process. 
         [0015]    The cap assembly may be fixed to the first and second metallic plates via welding or may be coated with epoxy and fixed to the first and second metallic plates via the epoxy. 
         [0016]    The insulator may include a polymer material having a melting temperature between about 100 degrees Celsius and about 130 degrees Celsius. The melting temperature of the polymer material may be about 110 degrees Celsius. 
         [0017]    The cap assembly may have an aperture, and the rechargeable battery may further include a plug insertable into the aperture for selectively closing the aperture. 
         [0018]    Each of the first and second metallic plates may include a base, walls extending from at least two opposing peripheral sides of the base, and flange portions protruding from respective ones of the walls in at least one direction substantially parallel to a surface of the base. 
         [0019]    According to embodiments of the present invention, a rechargeable battery is configured for preventing or substantially preventing explosion of the rechargeable battery resulting from overheating, and the stability of the rechargeable battery can be improved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is an exploded perspective view schematically showing a rechargeable battery according to a first exemplary embodiment of the present invention; 
           [0021]      FIG. 2  is a perspective view showing a base member and a cover member of the rechargeable battery of  FIG. 1  coupled together, and a cap assembly separated from the base member and the cover member; 
           [0022]      FIG. 3  is a perspective view schematically showing a generation member and a cap assembly of the rechargeable battery of  FIG. 1  coupled together; 
           [0023]      FIG. 4  is a perspective view showing electrode leads and an insulator of the cap assembly of the rechargeable battery of  FIG. 1  coupled together; 
           [0024]      FIG. 5  is a sectional diagram taken along line V-V of  FIG. 4 ; 
           [0025]      FIG. 6  is an exploded perspective view schematically showing a rechargeable battery according to a second exemplary embodiment of the present invention; 
           [0026]      FIG. 7  is an exploded perspective view showing a cap assembly of a rechargeable battery according to a third exemplary embodiment of the present invention; 
           [0027]      FIG. 8  is a bottom perspective view of an insulator of the cap assembly of  FIG. 7 ; 
           [0028]      FIG. 9  is a perspective view showing a cap assembly of a rechargeable battery according to a fourth exemplary embodiment of the present invention; 
           [0029]      FIG. 10  is a perspective view showing a cap assembly of a rechargeable battery according to a fifth exemplary embodiment of the present invention; and 
           [0030]      FIG. 11  is a perspective view showing a cap assembly of a rechargeable battery according to a sixth exemplary embodiment of the present invention. 
       
    
    
       [0031]    Description of Reference Numerals Indicating Some Elements in the Drawings 
         [0000]    
       
         
               
               
               
               
             
           
               
                   
               
             
             
               
                 10 
                 base member 
                 11 
                 lead-in portion 
               
               
                 13 
                 base flange portion 
                 20 
                 cover member 
               
               
                 30 
                 generation member 
                 31, 32 
                 connection members 
               
               
                 40 
                 cap assembly 
                 41, 42 
                 electrode leads 
               
               
                 43 
                 insulator 
                 45 
                 through-hole 
               
               
                   
               
             
          
         
       
     
       DETAILED DESCRIPTION 
       [0032]    A rechargeable battery according to exemplary embodiments of the present invention is described in detail with reference to the accompanying drawings. However, the present invention is not limited to the disclosed embodiments, but may be implemented in various ways. The embodiments are provided to complete the disclosure of the present invention and to allow those having ordinary skill in the art to understand the scope of the present invention. The present invention is defined by the scope of the claims including equivalents thereof. The same reference numbers will be used throughout the drawings to refer to the same or like parts. 
         [0033]    One exemplary embodiment of the present invention provides a rechargeable battery including a base member (“first metallic plate”), a cover member (“second metallic plate”) coupled to the base member by welding and configured to form a mounting space between the cover member and the base member, a generation member placed in the mounting space, connection members configured to respectively extend from positive and negative electrodes of the generation member, and a cap assembly configured to include electrode leads coupled to the respective connection members and an insulator coupled to the electrode leads and placed between the base member and the cover member. 
         [0034]    The cap assembly, in one embodiment, is forcibly inserted between the base member and the cover member. When the base member and the cover member are coupled together by welding, the cap assembly may be coupled between the base member and the cover member through melting. 
         [0035]    The cap assembly may be coated with epoxy and coupled between the base member and the cover member. The insulator may be configured to have a tapered shape in a width direction on both sides of a length direction, and may be made of polypropylene material. 
         [0036]    A through-hole communicating with the mounting space may be formed in the insulator, and a plug configured to selectively plug the through-hole may be inserted into the through-hole. 
         [0037]    The generation member may have a stack form or a jelly roll form. The cover member may have a plate form. 
         [0038]    In one embodiment, flange portions may be formed in the base member protruding along the edges of the base member for seating the cover member on the base member. 
         [0039]    According to another exemplary embodiment of the present invention, the edges of a cover member are curved in the direction of a base member, and cover flange portions are formed at the curved tips of the cover member. Base flange portions of a base member to which the cover flange portions are coupled may be formed along the edges of the base member. 
         [0040]    According to another exemplary embodiment of the present invention, a cap assembly includes a plurality of protrusion portions formed on each electrode lead and extending in a direction toward the insulator. A first face of the insulator in a length direction has a plane, and a face opposite the first face is tapered. Insertion holes into which the respective protrusion portions are inserted are formed on the first face. Accordingly, the insulator is configured to be coupled to the electrode leads. 
         [0041]    In one exemplary embodiment, each of the base member and the cover member is made of a metal, and the cover member is coupled to the base member by laser welding. Accordingly, the manufacturing cost can be reduced, and economic efficiency can be improved. Also, since the base member and the cover member are each formed of a metal material, a rechargeable battery of 8 mm or more in thickness can be provided. According to exemplary embodiments of the present invention, the cap assembly is automatically broken when overheating occurs within the rechargeable battery. 
         [0042]      FIG. 1  is an exploded perspective view schematically showing a rechargeable battery according to a first exemplary embodiment of the present invention.  FIG. 2  is a perspective view showing a state in which, when a base member and a cover member of  FIG. 1  are coupled together, a cap assembly is separated from the base member and the cover member.  FIG. 3  is a perspective view schematically showing a state in which a generation member of  FIG. 1  and the cap assembly are coupled together. 
         [0043]    As shown in  FIGS. 1 to 3 , a rechargeable battery  100  according to the first exemplary embodiment of the present invention includes a base member  10  (“first metallic plate”), a cover member  20  (“second metallic plate”) welded to the base member  10  and configured to form a mounting space between the cover member  20  and the base member  10 , a generation member  30  placed in the mounting space, connection members  31  and  32  configured to respectively extend from the positive and negative electrodes of the generation member  30 , and a cap assembly  40 . The cap assembly  40  includes electrode leads  41  and  42  coupled to the respective connection members  31  and  32  and an insulator  43  coupled to the electrode leads  41  and  42  and placed between the base member  10  and the cover member  20 . 
         [0044]    The base member  10  is formed as a polygon having edges, and includes a lead-in portion  11 , or wall, between which the generation member  30  is placed. The lead-in portion  11  forms a mounting space between the base member  10  and the cover member  20  coupled thereto, so the generation member  30  can be mounted between the lead-in portions  11 . In the exemplary embodiment of the present invention, although the base member  10  is illustrated as having a polygonal shape having edges, the base member  10  may have a shape that does not have edges, such as a round shape. As described above, if the base member  10  has a round shape without edges, the generation member  30  can be mounted on the base member  10  because the lead-in portion  11  is formed within the base member  10 . 
         [0045]    According to one exemplary embodiment, a base flange portion  13  protruding from edges of the base member  10  is formed on the side of the base member  10 . The cover member  20  is mounted on the base flange portion  13 . Alternatively, the base member  10  may be formed without the base flange portion  13 . 
         [0046]    The cover member  20 , in one embodiment, is welded to the base member  10 . The cover member  20  is configured to have a plate form and is seated over the base member  10 , so the cover member  20  and the base member  10  are coupled together along the edges of the base member  10 . The mounting space is formed within the base member  10  through the coupling of the cover member  20  and the base member  10 . Accordingly, the generation member  30  can be placed within the mounting space. The welding of the cover member  20  and the base member  10  may include arc welding, gas welding, or laser welding. However, the present invention may selectively use the arc welding, gas welding, and laser welding, as well as a combination thereof, rather than being limited to one of them. 
         [0047]    The base member  10  and the cover member  20 , in one embodiment, are made of a steel material or a stainless steel material. According to some exemplary embodiment, the cover member  20  and the base member  10  are coupled by welding and are formed of a metal other than aluminum, and the manufacturing cost can thereby be reduced. A variety of metal materials may be used in the rechargeable battery according to the present exemplary embodiment. Accordingly, inexpensive metal materials can be used and the manufacturing cost can be reduced. It is illustrated that the cover member  20  and the base member  10  according to one exemplary embodiment of the present invention are coupled by welding. However, in another exemplary embodiment, they may be coupled through a crimping process. 
         [0048]    The generation member  30  is placed in the mounting space formed by the coupling of the cover member  20  and the base member  10 . 
         [0049]    In an exemplary embodiment of the present invention, the generation member  30  may be placed in the mounting space in a stack form or a jelly roll form. The generation member of a stack form or a jelly roll form is known, so construction and a detailed description thereof are omitted in the exemplary embodiment of the present invention. The connection members  31  and  32  are configured to protrude from one side of the generation member  30  and extend from the respective positive and negative electrodes of the generation member  30 . The cap assembly  40  is coupled to the connection members  31  and  32 . 
         [0050]      FIG. 4  is a perspective view showing a state in which the electrode leads of the cap assembly and the insulator are coupled together, and  FIG. 5  is a sectional diagram taken along line V-V of  FIG. 4 . 
         [0051]    As shown in  FIGS. 4 and 5 , the cap assembly  40  includes the electrode leads  41  and  42  coupled to the respective connection members  31  and  32  (refer to  FIGS. 1 and 3 ) and the insulator  43  coupled to the electrode leads  41  and  42  and placed between the base member  10  and the cover member  20 . 
         [0052]    The electrode leads  41  and  42  may be coupled to the respective connection members  31  and  32  by welding. The electrode leads  41  and  42  may be coupled to the connection members  31  and  32  through the insulator  43 . A pair of the electrode leads  41  and  42  are coupled to the negative and positive electrodes via the connection members  31  and  32 . 
         [0053]    The insulator  43  is configured to support the electrode leads  41  and  42 , and is coupled to a side of the rechargeable battery  100  having an opening portion  12  (see  FIG. 2 ) formed in the side between where the base member  10  and the cover member  20  are coupled together. The lead-in portion  11  and the base flange portion  13  are not formed at the side of the base member  10  where the opening portion  12  is formed. 
         [0054]    The insulator  43 , in one exemplary embodiment, is forcibly fit into the opening portion  12 . To this end, the insulator  43  has a larger size than that of the opening of the opening portion  12 . In one embodiment, the insulator  43  is formed to have a polygonal shape having edges, and the side of the insulator  43  in a width direction may be tapered. The tapering faces of the insulator  43  may be formed in the width direction thereof on the top and bottom of the length direction. With reference to  FIG. 5 , a taper angle (α) of the insulator  43  may be between about 1° and about 10°. If the taper angle of the insulator  43  is less than 1°, fitting pressure in the opening portion  12  is very low. If the taper angle of the insulator  43  is greater than 10°, pressure is excessively applied between the opening portion  12  and the insulator  43 . Accordingly, the taper angle of the insulator  43  is formed to be between about 1° and about 10° so that the insulator  43  can be forcibly fit into the opening portion  12  without excessive pressure. Further, the insulator  43 , in one exemplary embodiment, is made of a polypropylene material. 
         [0055]    The insulator  43  may be made of a polypropylene material because when the insulator  43  is forcibly fit into the opening portion  12 , as described above, it prevents or substantially prevents the rechargeable battery  100  from exploding. In more detail, polypropylene has a property that it is easily melted at 110° C. or more. Thus, when the temperature rises because of an abnormality of the rechargeable battery  100 , the insulator  43  melts, thereby opening a portion of the opening portion  12  of the rechargeable battery  100 . Consequently, since the opening portion  12  is opened, pressure within the rechargeable battery  100  drops. Accordingly, unexpected explosion can be prevented, and a structure with improved stability can be provided. Alternatively, in other exemplary embodiments of the present invention, the material of the insulator  43  is not limited to polypropylene and may include a polymer material that melts at a temperature between about 100° C. and about 130° C., such as a temperature near 110° C. 
         [0056]    When the insulator  43  is mounted, epoxy (not shown) may be used as an assistant mounting medium. The cap assembly  40  constructed with the epoxy, when the cover member  20  and the base member  10  are coupled together by welding, may be forcibly fit into the opening  12  and coupled together through thermal compression. That is, the epoxy and the insulator  43  may be partially melted and thermally compressed by heating a portion where the cap assembly  40  contacts the cover member  20  and the base member  10  from outside while the cap assembly  40  is press-fit into the opening portion  12 . 
         [0057]    Further, a through-hole  45  may be formed in the insulator  43  such that it faces the generation member  30 . The through-hole  45  may be formed in order to inject an electrolytic into the rechargeable battery. A plug member  47  functions to selectively open or shut the through-hole  45  and may be inserted into the through-hole  45 . One or more through-holes  45  may be formed in the length direction of the insulator  43 . 
         [0058]    If gas is generated within the rechargeable battery when the rechargeable battery  100  is charged or discharged, the plug member  47  opens the through-hole  45  so that the gas within the rechargeable battery can be discharged. Further, a vent (not shown) may be formed in the through-hole  45  so that gas can be easily discharged through the vent. 
         [0059]    As described above, in the rechargeable battery  100  according to one exemplary embodiment, the cover member  20  is made of a metal material, and the base member  10  and the cover member  20  are coupled together by welding. Accordingly, a rechargeable battery of 8 mm or more in thickness can be provided. 
         [0060]    The operation of the rechargeable battery  100  constructed according to one exemplary embodiment is described below. 
         [0061]    First, the cover member  20  is welded to the base member  10 . The generation member  30  is placed in the space between the base member  10  and the cover member  20 . Since the base member  10  and the cover member  20  are coupled together via welding, the rechargeable battery  100  can be formed at a thickness of 8 mm or more. 
         [0062]    Here, the opening portion  12  is formed on the side of the base member  10  and the cover member  20 , and the cap assembly  40  is forcibly fit into the opening portion  12  and coupled thereto during the welding process. If the temperature of the rechargeable battery increases excessively, the insulator  43  melts, thereby opening the opening portion  12 . Accordingly, the explosion of the rechargeable battery can be prevented. 
         [0063]    An electrolytic solution is supplied through the through-hole  45  formed in the insulator  43  of the cap assembly  40 . The plug member  47  may be inserted into the through-hole  45  for selectively plugging the through-hole  45 . 
         [0064]    As described above, the rechargeable battery according to exemplary embodiments of the present invention has a thickness of 8 mm or more and is configured having a structure that is capable of preventing or substantially preventing explosion when the pressure therein is abnormal. 
         [0065]      FIG. 6  is an exploded perspective view schematically showing a rechargeable battery  200  according to another exemplary embodiment of the present invention. The same reference numerals as those of  FIGS. 1 to 5  are used to identify the same members having the same functions. Hereinafter, a detailed description of the same reference numerals is omitted. 
         [0066]    As shown in  FIG. 6 , cover flange portions  121  are formed on the sides of a cover member  120 . The cover flange portions  121  are formed along the edges of the cover member  120 . The cover flange portions  121  are configured to adjoin a base flange portion  13 ′ of a base member  10 ′ and are coupled to the base flange portion  13 ′ by welding. The cover member  120  may include lead-in portions, or walls, from which the cover flange portions  121  extend (as depicted in  FIG. 6 ), or in an alternative embodiment, may include lead-in portions but not the cover flange portions  121 . 
         [0067]      FIG. 7  is an exploded perspective view showing a cap assembly of a rechargeable battery according to another exemplary embodiment of the present invention, and  FIG. 8  is a perspective view showing a face in which insertion holes of an insulator of the cap assembly of  FIG. 7  are formed. 
         [0068]    The same reference numerals as those of  FIGS. 1 to 5  are used to identify the same members having the same functions. Hereinafter, a detailed description of the same reference numerals is omitted. 
         [0069]    As shown in  FIGS. 7 and 8 , a cap assembly  340  of a rechargeable battery according to another exemplary embodiment of the present invention includes a plurality of protrusion portions  345  formed on each of electrode leads  341 . Insertion holes  347  into which the respective protrusion portions  345  are inserted are formed in an insulator  343 . Accordingly, the electrode leads  341  and  342  and the insulator  343  may be coupled together by forcibly inserting the protrusion portions  345  into the respective insertion holes  347 . 
         [0070]    In one embodiment, one face A of the insulator  343  in which the insertion holes  347  are formed is flat, and the other face B opposite to the face A is tapered. Accordingly, the electrode leads  341  may be coupled to the insulator  343 , and the insulator  343  may be easily fit into the opening portion  12 . 
         [0071]      FIG. 9  is a perspective view showing an assembled state of electrode leads and an insulator of a cap assembly  440  of a rechargeable battery according to another exemplary embodiment of the present invention. 
         [0072]    Referring to  FIG. 9 , the cap assembly  440  is formed by coupling electrode leads  441  and  442  with an insulator  443 , and at least one hole  441   a  and  442   a  is formed on each of the respective electrode leads  441  and  442 . Each of the holes  441   a  and  442   a  may be formed as a through hole or a recess, and may improve coupling adhesion when the electrode leads  441  and  442  are coupled to the insulator  443  by providing an increase of friction at the hole  441   a  and  442   a  between the electrode leads  441  and  442  and the insulator  443 . 
         [0073]      FIG. 10  is a perspective view showing an assembled state of electrode leads and an insulator of a cap assembly  540  of a rechargeable battery according to another exemplary embodiment of the present invention. 
         [0074]    Referring to  FIG. 10 , the cap assembly  540  is formed by coupling electrode leads  541  and  542  with an insulator  543 , and a groove  543   a  is formed along the periphery of the insulator  543  which contacts a base member and a cover member of the rechargeable battery near an opening to a cavity therebetween to improve sealing of the opening. Two or more grooves  543   a  may be formed in parallel, which may further improve a sealing capability of the cap assembly  540 . 
         [0075]      FIG. 11  is a perspective view showing an assembled state of electrode leads and an insulator of a cap assembly  640  of a rechargeable battery according to another exemplary embodiment of the present invention. 
         [0076]    Referring to  FIG. 11 , the cap assembly  640  is formed by coupling electrode leads  641  and  642  with an insulator  643 , and the insulator  643  is covered with a metallic case  646  along the periphery of the insulator  643  which contacts a base member and a cover member of the rechargeable battery. The insulator  643  covered with the metallic case  646  may be coupled to the base member and the cover member by welding. 
         [0077]    The exemplary embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the exemplary embodiments, but may be modified in various ways by those having ordinary skill in the art. Accordingly, the scope of the present invention should be defined by the claims.