Abstract:
A rechargeable battery and its fabrication method prevents electrical shorts between the electrode plates by decreasing shrinkage of the separator, the battery includes: an electrode assembly including: a wound electrode jelly roll having a first electrode plate with a first electrode tab attached thereto, a second electrode plate with a second electrode tab attached thereto and a separator interposed between the first electrode plate and the second electrode plate, and an upper tape arranged to surround an upper end of the electrode jelly roll where the first electrode tab and second electrode tab extend outward therefrom; a case having an upper end opening arranged to receive the electrode assembly and an electrolyte; and a cap assembly arranged to seal the upper end opening of the case after the electrode assembly has been received in the case; the upper tape 1I is attached to the upper end of the electrode jelly roll and surrounds the separator adjacent to an end of an innermost electrode plate of the first and second electrode plates.

Description:
CLAIM OF PRIORITY 
       [0001]    This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for RECHARGEABLE BATTERY earlier filed in the Korean Intellectual Property Office on the 19 th  of Mar. 2007 and there duly assigned Serial No. 2007-0026632. 
       BACKGROUND OF INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a rechargeable battery and its fabrication method, and more particularly, the present invention relates to a rechargeable battery and its fabrication method, the battery preventing electrical shorts between the electrode plates by decreasing shrinkage of a separator of the battery. 
         [0004]    2. Description of the Related Art 
         [0005]    Various batteries have been used as a power source of small electronic devices. As a power source of portable phones, notebook computers, camcorders and the like, the battery using an electrolyte, such as a lithium rechargeable battery that is a small sealed battery of a large capacity has been generally used. As such an electrolyte battery, a cylindrical or a prismatic type battery has been used. 
         [0006]    Generally, a rechargeable battery, such as a lithium rechargeable battery and a lithium polymer battery includes an electrode assembly with an electrolyte contained within the case. The electrode assembly includes a positive electrode plate, a separate and a negative electrode plate. The positive electrode plate (or negative electrode plate) includes a positive electrode (or negative electrode) collector in the type of foil and a positive electrode active material coated on the surface of the positive electrode collector. An uncoated region in which an active material has not been coated is formed on the collector of the plates, and an electrode tab is generally welded to the uncoated region for connection to an external circuit. 
         [0007]    In more detail, the lithium rechargeable battery is formed by respectively coating an active material on the positive electrode collector and negative electrode collector and arranging it in a case as an electrode assembly of a wound jelly-roll type having a separator interposed between the collectors, and injecting an electrolyte and covering the opening of the case with a cap assembly. 
         [0008]    The lithium rechargeable battery is classified into a cylindrical type battery having a jelly-roll arranged within a cylindrical case, and a prismatic type battery having the jelly-roll arranged within a prismatic case. However, the prismatic type rechargeable battery has been generally used for small or thin devices having a rectangular receptacle. 
         [0009]    In the prismatic rechargeable battery, to arrange the electrode assembly in the case, the electrode assembly is wound, fixed by a finishing tape, and then pressed. 
         [0010]    In other words, the finishing tape is attached by wrapping the end portion where the winding of the jelly-roll type electrode assembly has been finished at the circumferential surface of the jelly-roll type electrode assembly that is formed by winding a positive electrode plate, a separator and a negative electrode plate in sequence. 
         [0011]    The positive electrode plate and negative electrode plate are formed generally by coating and filling an active material for a metal base, and drying, roll-pressing and cutting the metal base even though it is somewhat different depending on the kind of the rechargeable battery. For a lithium rechargeable battery, a lithium transition metal oxide is used as the active material of the positive electrode plate and aluminum is used as a collector of the positive electrode plate. Furthermore, carbon and carbon composite are used as the active material of the negative electrode plate and copper is used as a collector of the negative electrode plate. 
         [0012]    Furthermore, the separator separates the positive electrode plate and the negative electrode plate so as to not directly contact to cause electrical shorts. A micro-porous film made of polyolefin resin, such as polyethylene or polypropylene, is used as the separator. 
         [0013]    The separator is formed longer than the positive electrode plate and the negative electrode plate for preventing an electrical short caused by contact between the positive electrode plate and negative electrode plate when winding the positive electrode plate, the separator and the negative electrode plate. 
         [0014]    However, an outmost base portion of the electrode assembly that the winding has been completed is fixed by a finishing tape after the positive electrode plate of aluminum (or the negative electrode plate of copper) has been finally wound and finished. In other words, the finishing tape is attached on the surface of the positive electrode collector of the positive electrode located at the outmost of the wound electrode assembly. 
         [0015]    As described above, the finishing tape finishes the wound electrode assembly and simultaneously holds the positive electrode plate attached to the surface of the positive electrode collector of the positive electrode. However, because this finishing tape is not directly attached to the separator for preventing electrical shorts between the positive electrode plate and the negative electrode plate by being interposed between the positive electrode plate and the negative electrode plate, the finishing tape can not well hold the separator so as not to be deformed. 
         [0016]    Accordingly, when the separator made of resin shrinks horizontally or longitudinally (vertically) due to a charge or discharge of the battery or a heat shock, especially when the separator shrinks horizontally or longitudinally (vertically) as a result of an electrode tab generating a large amount of heat at the upper region of the electrode assembly where much of the electrical current flows, because the separator shrinks and simultaneously the end portions of the positive electrode plate and the negative electrode plate contact each other, thereby causing an electrical short. 
       SUMMARY OF THE INVENTION 
       [0017]    Accordingly, an object of the present invention is to provide a rechargeable battery and its fabrication method, the battery preventing electrical shorts between the electrode plates by decreasing the shrinkage of the separator. 
         [0018]    According to one aspect of the present invention, a rechargeable battery is provided, the battery including: an electrode assembly including: a wound electrode jelly roll having a first electrode plate with a first electrode tab attached thereto, a second electrode plate with a second electrode tab attached thereto and a separator interposed between the first electrode plate and the second electrode plate, and an upper tape arranged to surround an upper end of the electrode jelly roll where the first electrode tab and second electrode tab extend outward therefrom; a case having an upper end opening arranged to receive the electrode assembly and an electrolyte; and a cap assembly arranged to seal the upper end opening of the case after the electrode assembly has been received in the case; the upper tape is attached to the upper end of the electrode jelly roll and surrounds the separator adjacent to an end of an innermost electrode plate of the first and second electrode plates. 
         [0019]    The first electrode plate may include: a first electrode collector, a first electrode active material layer coated on both surfaces of the first electrode collector, a first uncoated electrode region at both ends of the first electrode collector where the first electrode active material layer has not been coated, and wherein the first electrode tab is attached to one end of the first uncoated electrode region; and the second electrode plate may include a second electrode collector, a second electrode active material layer coated on both surfaces of the second electrode collector, a second uncoated electrode region at both ends of the second electrode collector where the second electrode active material layer has not been coated, and wherein the second electrode tab is attached to one end of the second uncoated electrode region; and the second electrode tab is arranged on one side of the electrode jelly roll about a center of the electrode jelly roll and the first electrode tab is located on another side of the electrode jelly roll about the center of the electrode jelly roll. 
         [0020]    The upper tape may be attached to surround the separator arranged between an end of the electrode active material layer and an end of the uncoated electrode region of an innermost one of the first and second electrode plates. 
         [0021]    The first electrode plate may be a positive electrode plate and the second electrode plate may be a negative electrode plate. 
         [0022]    The winding of the electrode jelly roll may be arranged from a center thereof in an order of the second electrode plate, the separator and the first electrode plate. 
         [0023]    The upper tape may be attached to a first region including the separator between an end of the second electrode active material layer and an end of the second uncoated electrode region of the second electrode plate. The upper tape may be attached to a second region opposite to the first region about the center of the electrode jelly roll. 
         [0024]    The first region may be arranged outside of the second electrode tab in a first direction about the center of the electrode jelly roll, and the second region may be arranged outside of the first electrode tab in a second direction about the center of the electrode jelly roll. 
         [0025]    The upper tape may be attached between the first electrode tab and the second electrode tab about the center of the electrode jelly roll. The upper tape may include an insulating material having a high heat resistance. The upper tape may include an adhesive coated on a synthetic resin selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP) and polyimide (PI). The upper tape may fix the separator projected outward from the upper end of the electrode jelly roll more than the first electrode plate and second electrode plate. The upper tape may surround a pair of long sides of an upper face of the electrode jelly roll and side faces thereof and may continue to the upper face. 
         [0026]    The electrode assembly may include a finishing tape surrounding an outmost layer of the electrode jelly roll. The electrode assembly may include a lower tape surrounding a lower end of the electrode jelly roll. 
         [0027]    The upper tape may have the same thickness as the lower tape. 
         [0028]    According to another aspect of the present invention, a method of fabricating a rechargeable battery is provided, the method including: fabricating an electrode assembly including: winding an electrode jelly roll having a first electrode plate with a first electrode tab and a second electrode plate with a second electrode tab and a separator interposed between the first electrode plate and the second electrode plate; arranging an upper tape to surround an upper end of the electrode jelly roll where the first electrode tab and second electrode tab extend outward therefrom; arranging the electrode assembly within an upper end opening of a case; arranging a cap assembly to cover the upper end opening of the case after the electrode assembly has been received in the case; and injecting an electrolyte and sealing the rechargeable batter; wherein the upper tape is attached to the upper end of the electrode jelly roll and surrounds the separator adjacent to an end of an innermost electrode plate of the first and second electrode plates. 
         [0029]    The first electrode plate may include a first electrode collector, a first electrode active material layer coated on both surfaces of the first electrode collector, a first uncoated electrode region at both ends of the first electrode collector where the first electrode active material layer has not been coated, and the first electrode tab is attached to one end of the first uncoated electrode region; and the second electrode plate may include a second electrode collector, a second electrode active material layer coated on both surfaces of the second electrode collector, a second uncoated electrode region at both ends of the second electrode collector where the second electrode active material layer has not been coated, and wherein the second electrode tab is attached to one end of the second uncoated electrode region; and the second electrode tab is arranged on one side of the electrode jelly roll about a center of the electrode jelly roll and the first electrode tab is located on another side of the electrode jelly roll about the center of the electrode jelly roll. 
         [0030]    The upper tape may be attached to surround the separator arranged between an end of the electrode active material layer and an end of the uncoated electrode region of an innermost one of the first and second electrode plates. 
         [0031]    The electrode jelly roll may be wound from a center thereof in an order of the second electrode plate, the separator and the first electrode plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    A more complete appreciation of the present invention, and many of the attendant advantages thereof, will be readily apparent as the present invention becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
           [0033]      FIG. 1  is an exploded perspective view of a rechargeable battery according to one exemplary embodiment of the present invention; 
           [0034]      FIG. 2  is a perspective view of an electrode assembly of the rechargeable battery of  FIG. 1 ; 
           [0035]      FIG. 3  is a view of the layout of an electrode jelly roll before being wound in the electrode assembly of  FIG. 2 ; 
           [0036]      FIG. 4  is an enlarged partial perspective view of a portion of the upper end of the electrode jelly roll in the electrode assembly of  FIG. 1 ; 
           [0037]      FIG. 5  is a plan view of the upper end of the electrode jelly roll where an upper tape is attached in the electrode assembly of  FIG. 1 ; and 
           [0038]      FIG. 6  is a perspective view of an electrode assembly of a rechargeable battery according to another exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0039]    Hereinafter, exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings. 
         [0040]      FIG. 1  is an exploded perspective view of a rechargeable battery according to one exemplary embodiment of the present invention, and  FIG. 2  is a perspective view of an electrode assembly of the rechargeable battery of  FIG. 1 , and  FIG. 3  is a view of the layout of an electrode jelly roll before being wound into the electrode assembly of  FIG. 2  and  FIG. 4  is an enlarged partial perspective view of a portion of the upper end of the electrode jelly roll in the electrode assembly of  FIG. 1 . 
         [0041]    Referring to  FIG. 1 , the rechargeable battery  400 , for example, a prismatic type rechargeable battery, includes an electrode assembly  100  on which an upper tape  140  is attached, a case  200  that receives the electrode assembly  100  and an electrolyte (not shown), and a cap assembly  300  sealing the upper opening  200 a of the case  200  as shown in  FIG. 1 . 
         [0042]    Referring to  FIG. 2  and  FIG. 3 , the electrode assembly  100  includes an electrode jelly roll  110 , a finishing tape  120  for finishing the electrode jelly roll  110 , a lower tape  130  attached to surround the lower end of the electrode jelly roll  110 , and an upper tape  140  attached to surround the upper end of the electrode jelly roll  110 . 
         [0043]    The electrode jelly roll  110  includes a first electrode plate  113 , a second electrode plate  115  and a separator  114  interposed between the first electrode plate  113  and the second electrode plate  115 . The first electrode plate  113 , the second electrode plate and the separator  114  are wound altogether. 
         [0044]    The first electrode plate  113  includes a first electrode active material layer  11   3 b coated on both faces of a first electrode collector  113   a  formed of a highly conductive thin metal plate, for example, aluminum (Al) foil. As the first electrode active material, a chalcogenide compound is used. For example, composite metal oxides, such as LiCoO 2 , LiMn 2 O 4 , LiNiO 2 , LiNi 1-x , Co x O 2  (0&lt;x&lt;1), LiMnO 2  can be used. However, the present invention is not limited thereto. A first uncoated electrode region  113   c  that is not provided with the first active material layer  113   b  is located on both ends of the first electrode collector  113   a , and a first electrode tab  116  is formed at one end of the first uncoated electrode region  113   c . The one end of the first electrode tab  116  is electrically coupled to the first uncoated electrode region  113   c , and the other end extends outside. The first electrode plate  113  may be a positive electrode plate that functions as a positive electrode. 
         [0045]    The second electrode plate  115  includes a second electrode active material layer  115   b  coated on both faces of a second electrode collector  115   a  formed of a conductive thin metal plate, for example, copper (Cu) or nickel (Ni) foil. As the second electrode active material, a carbon material, Si, Sn, tin oxide, composite tin alloys, a transition metal oxide and lithium metal nitride or lithium metal oxide can be used. However, the present invention is not limited thereto. A second uncoated electrode region  115   c  that is not provided with the second active material layer  115   b  is located on both ends of the second electrode collector  115   a , and a second electrode tab  117  is formed at one end of the second uncoated electrode region  115   c . One end of the second electrode tab  117  is electrically coupled to the second uncoated electrode region  115   c , and the other end extends outside. The second electrode tab  117  may be located on one side of the electrode jelly roll  110  about the center C of the electrode jelly roll  110 , and the first electrode tab  116  may be located on the other side of the electrode jelly roll  110 . The second electrode plate  115  may be a negative electrode plate that functions as a negative electrode. 
         [0046]    The separator  114  is provided to prevent electrical shorts between the first electrode plate  113  and the second electrode plate  115 , and is formed of any material selected from the group consisting of polyethylene, polypropylene and a copolymer of polyethylene and polypropylene. However, the present invention is not limited thereto. The separator  114  is preferably formed wider in a vertical direction than the first electrode plate  113  and the second electrode plate  115  in order to prevent electrical shorts between the first electrode plate  113  and the second electrode plate  115 . Accordingly, the separator  114  extends outside from the wound electrode jelly roll  110  more than the first electrode plate  113  and the second electrode plate  115 . 
         [0047]    The first electrode plate  113  and the second electrode plate  115 , a first electrode tap  116  and a second electrode tabs  117  may be located with the polarity interchanged, and an insulation member  118  may be wound on the border region where the first electrode tap  116  and the second electrode tab  117  respectively extend outwards from the first electrode plate  113  and the second electrode plate  115  to prevent electrical shorts between the tabs  116  and  117  and the two electrode plates  113  and  115 . 
         [0048]    A finishing tape  120  is attached to surround the outmost layer of the electrode jelly roll  110  that is formed by winding the first electrode plate  113 , the separator  114  and the second electrode plate  115  together. The finishing tape  120  may be an adhesive tape having an insulation property and a high heat resistance. The outmost layer of the electrode jelly roll  110  is the first electrode plate  113  and may be the second electrode plate  115  according to the embodiment of the present invention. 
         [0049]    The external appearance of the electrode jelly roll  110  finished by the finishing tape  120  is constituted of an upper face  110   a  that the first electrode tab  116  and the second electrode tab  117  extend outwards from, a pair of long side faces  110   b  and a pair of short side faces  110   c  that are continued to the upper face, and a lower face  110   d.    
         [0050]    According to the present invention, the region that the first electrode tab  116  and the second electrode tab  117  extend outwards from is called an upper end of the electrode jelly roll  110 , and the opposite end to the upper end is called a lower end thereof. 
         [0051]    The lower tape  130  is attached by arranging the lower face  110   d  and the pair of long side faces  110   b  of the electrode jelly roll  110  so as to surround the lower end of the electrode jelly roll  110 . The lower tape  130  fixes the separator  114  projected from the lower end of the electrode jelly roll  110  more than the first electrode plate  113  and the second electrode plate  115 , and additionally, enables the electrode assembly  100  to be easily interposed without any interference with the upper opening  200   a  of the battery case  200  when the electrode assembly  100  is inserted inside a case  200  that is described hereinafter. The lower tape  130  may be also an adhesive tape like as the finishing tape  120 . 
         [0052]    The upper tape  140  is attached by arranging the upper face  110   a  and the pair of long side faces  110   b  of the electrode jelly roll  110  so as to surround the upper end of the electrode jelly roll  110 . The upper tape  140  is attached to the outside of the second electrode tab  117  in first direction (D 1 ) from the center(C) of the electrode jelly roll  110  and to the outside of the first electrode tab  116  in the second direction (D 2 ) from the center(C) of the electrode jelly roll  110 . 
         [0053]    The upper tape  140  is attached to the separator  114  extending outwards from the upper end of the electrode jelly roll  110  more than the first electrode plate  113  and the second electrode plate  115  and fixes the separator  114  as shown in  FIG. 4 . The separator  114  is fixed by the upper tape  140  so that the separator  114  can be prevented from shrinking in a vertical direction that is a longitudinal direction of the electrode assembly  100  or in horizontal direction by heat generated due to an overcharge of the rechargeable battery. In more detail, a large amount of heat is generated at the upper end of the electrode jelly roll  110  due to an electrical current flow through the first electrode tab  116  and the second electrode tab  117  during the charging or discharging of the rechargeable battery. The upper tape  140  take a significant role in preventing the separator  114  from shrinking due to the heat. Accordingly, the upper tape  140  prevents the separator  114  at the upper end of the electrode jelly roll  110  from shrinking, thereby preventing electrical shorts between the first electrode plate  113  and the second electrode plate  115 . 
         [0054]    The upper tape  140  has the same thickness as the lower tape  130  so as not to increase the thickness of the electrode jelly roll  110 . Furthermore, the upper tape  140  is formed by coating an adhesive on a resin host material having an insulation property and a high heat resistance like the lower tape  130 , for example, any material selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP) and polyimide (PI). 
         [0055]    The case  200  is formed of aluminum or an aluminum alloy having a roughly rectangular shape. The electrode assembly  100  is received in the case  200  through the upper opening  200   a  of the case  200  so that the case  200  functions as a receptacle to receive the electrode assembly  100  and the electrolyte. The case  200  itself can function as a terminal. According to the present invention, because the outmost layer of the electrode assembly  100  is the first electrode plate  113 , the case  200  functions as a positive electrode. 
         [0056]    The cap assembly  300  includes a cap plate  333 , an insulation plate  336 , a terminal plate  339  and an electrode terminal  331 . A gasket tube  332  is interposed between the cap plate  333  and the electrode terminal  331 , and the electrode terminal  331  and the terminal plate  339  are electrically coupled to each other. The insulation plate  336  insulates the cap plate  333  from the terminal plate  339 . An electrolyte injection hole  335  is formed on one side of the cap plate  333 . A stopper  340  is provided with the electrolyte injection hole  335  for sealing the electrolyte injection hole after the electrolyte has been injected. 
         [0057]    An insulation case  250  is provided between the cap assembly  300  and the electrode assembly  100 , more particularly, on the upper face of the electrode assembly  100  at the lower portion of the cap assembly. A first electrode tab through-hole  251  is formed on one side of the insulation case  250  for the second electrode tab  117  passing, and a second electrode tab through-hole  252  is formed on another side of the insulation case, that is, to the position corresponding to the first electrode tab  116 . In addition, an electrolyte through-hole  253  is further formed on another side of the insulation case  250 . The electrolyte feeding hole may not be formed additionally. 
         [0058]    Hereinafter, the position where the upper tape  140  is attached to the upper end of the electrode jelly roll  110  to prevent the separator  114  from shrinking is described in detail with reference to  FIG. 5 . 
         [0059]      FIG. 5  is a plan view of the upper end of the electrode jelly roll where an upper tape is attached in the electrode assembly of  FIG. 1   
         [0060]    The upper tape  140  is attached to the end of one electrode plate of the first electrode plate  113  and the second electrode plate  115  that the winding of the electrode jelly roll  110  is finished prior to the other electrode plate so as to surround the separator at the upper end of the electrode jelly roll  110 . 
         [0061]    For example, as shown in  FIG. 5 , when the winding of the electrode jelly roll  10  is finished in order of the second electrode plate  115 , the separator  114  and the first electrode plate  113 , the upper tape  140  is attached so as to surround the end of the second electrode plate  115  where the winding is finished prior at the upper end of the electrode jelly roll  110 , that is, so as to surround a region of the section A between the second uncoated electrode region  115   c  and the end of the separator  114 . This is to prevent the second electrode plate  115  and the first electrode plate  113  from contacting each other even if the separator  114  shrinks in horizontal direction by the heat generated due to an overcharge of the rechargeable battery. 
         [0062]    In addition, the upper tape  140  may be attached so as to surround the separator close to the gap between the end of the electrode active material layer and the uncoated electrode region of the electrode plate that the winding of the electrode jelly roll  110  is finished prior to the other electrode plate. 
         [0063]    For example, as shown in  FIG. 5 , when the winding of the electrode jelly roll  110  is finished in order of the second electrode plate  115 , the separator  114  and the first electrode plate  113 , the upper tape  140  may be attached to a first region S 1  including the separator  114  adjacent in between the end  115   bb  of the second electrode active material layer and the end  115   cc  of the second uncoated electrode region of the second electrode plate  115  that the winding of the electrode jelly roll  110  is finished prior to the other electrode plate. This is to prevent electrical shorts caused by the contact at least between the first uncoated electrode region  113   c  and the second electrode active material layer  115   c  because the spark due to an electrical short between the first uncoated electrode region  113   c  and the second electrode active material layer  115   c  is most strong and has a great possibility of firing among an electrical short between the first uncoated electrode region  113   c  and the second uncoated electrode region  115   c , an electrical short between the first uncoated electrode region  113   c  and the second electrode active material layer  115   c , an electrical short between the first electrode active material layer  113   b  and the second uncoated electrode region  115   c  and an electrical short between the first electrode active material layer  113   b  and the second electrode active material layer  115   b.    
         [0064]    The upper tape  140  is attached to a first region S 1  including the separator  114  in between the end  115   bb  of the second electrode active material layer and the end  115   cc  of the second uncoated electrode region of the second electrode plate  115  that the winding of the electrode jelly roll  110  is finished prior to the other electrode plate and fixes the separator  114  between the end  115   bb  of the second electrode active material layer and the end  115   cc  of the second uncoated electrode region, to thereby prevent the separator  114  from shrinking due to heat in a horizontal direction to the region where the end  115   bb  of the second electrode active material layer and the first uncoated electrode region  113   c  face each other. Accordingly, an electrical short due to the contact between the second electrode active material layer  115   b  and the first uncoated electrode region  113   c  is prevented so that the spark and firing between the second electrode active material layer  115   b  and the first uncoated electrode region  113   c  can be prevented. Therefore, the safety of the rechargeable battery can be improved. 
         [0065]    The upper tape  140  may be attached to not only the first region S 1  including the separator  114   a  in between the end  115   bb  of the second electrode active material layer and the end  115   cc  of the second uncoated electrode region of the second electrode plate  115  that the winding of the electrode jelly roll  110  is finished prior to the other electrode plate, but also to a second region S 2  opposite to the first region S 1  about the center(C) of the electrode jelly roll  110 . This is to prevent the separator  114  from shrinking more efficiently by fixing the separator  114  well balanced at the upper end of the electrode jelly roll  110 . 
         [0066]    In the rechargeable battery according to the above-noted example of the present invention, because the separator  114  extending outwardly from the upper end of the electrode jelly roll  110  is fixed by the upper tape  140 , it is possible to prevent the separator  114  from shrinking in a longitudinal(vertical) direction or in a horizontal direction due to the heat caused by charging or discharging of the battery. Accordingly, an electrical short between the first electrode plate  113  and the second electrode plate  115  is prevented. Therefore, the safety of the rechargeable battery can be improved by preventing the firing due to electrical shorts between the electrode plates. 
         [0067]      FIG. 6  is a perspective view of an electrode assembly of a rechargeable battery according to another exemplary embodiment of the present invention. 
         [0068]    The rechargeable battery according to another embodiment of the present invention has the same construction and function as the rechargeable battery of the first embodiment of the present invention except that an upper tape  540  is further attached to an electrode jelly roll  510  of an electrode assembly  500 . Therefore, the overlapped explanation will be omitted about the same elements and functions. 
         [0069]    Referring to  FIG. 6 , in the electrode assembly  500  of the rechargeable battery according to another example of the present invention, compared with the electrode assembly  100  of the rechargeable battery  400  according to the first example of the present invention, the upper tape  540  attached on both sides of the upper end is further attached between a first electrode tab  516  and a second electrode tab  517 . 
         [0070]    Therefore, the electrode assembly  500  fixes more efficiently the separator  514  of the electrode jelly roll  510 , compared with the electrode assembly  100  of the rechargeable battery  400 , thereby preventing the separator  514  from being shrunk by heat. Accordingly, electrical shorts between the first electrode plate  513  and the second electrode plate  515  that are generated by the shrinking of the separator  514  can be prevented and so the safety of the rechargeable battery can be improved. 
         [0071]    In addition, although the electrode assemblies ( 100  and  500 ) fixing the separators ( 114  and  514 ) by attaching the upper tapes ( 140  and  540 ) has been explained as applied to the prismatic rechargeable battery, they can be applied to a polymer type rechargeable battery. 
         [0072]    The rechargeable battery according to the present invention produces the following effects. The separator extending from the upper end of the electrode jelly roll to the outside is fixed by surrounding the upper end of the electrode jelly roll with the upper tape, thereby preventing the separator from shrinking in the longitudinal(vertical) direction or in the horizontal direction due to heat. 
         [0073]    It should be understood by those of ordinary skill in the art that various replacements, modifications and changes in the form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. Therefore, it is to be appreciated that the above described embodiments are for purposes of illustration only and are not to be construed as being limitations of the present invention.