Abstract:
A secondary battery that can simplify manufacturing of an assembly of a bare cell and a protection circuit module, and reduce manufacturing costs by installing a connecting member of a protection circuit module electrically coupled to a bare cell in one direction of the bare cell. The secondary battery may be constructed with a bare cell; a protection circuit module installed on one edge side surface of the bare cell; first and second electrode terminals included in the bare cell; and first and second lead plates respectively configured to electrically couple the protection circuit module to the first and second electrode terminals, wherein the first and second lead plates are installed on the same single side edge surface between side surfaces of the bare cell.

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 SECONDARY BATTERY earlier filed in the Korean Intellectual Property Office on 15 Mar. 2007 and there duly assigned Serial No. 10-2007-0025350. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a secondary battery, and more particularly, to a secondary battery that can simplify a manufacturing process for an assembly of a bare cell and a protection circuit module, and reduce manufacturing costs. 
         [0004]    2. Description of the Related Art 
         [0005]    Generally, as lightweight and high-function portable wireless devices, such as video cameras, cellular phones, portable computers, and others, have been developed, a lot of research on the secondary battery which are used as a driving power supply of the portable wireless device has been performed. For example, the secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, a nickel-zinc battery and lithium secondary batteries, etc. Among them, the lithium secondary battery is widely used for an electronic appliance field because the lithium secondary battery can be recharged and the size can be miniaturized, and the lithium secondary battery has a high capacity, a high operating voltage and a high energy density per unit weight. 
         [0006]    The lithium secondary battery is formed by mounting a safety device, such as a PTC (positive temperature coefficient) element, a thermal fuse and a protection circuit module, on an electrode assembly including a cathode, an anode and a separator. A can receives the electrode assembly and an electrolyte, and a bare cell seals an upper end opening of a can by a cap assembly, and is received in a separate packing case, or filled with hot melt resin, tubed and labeled by a thin packing material. The safety devices prevent fire or explosion by shutting down an electric current, when an interior temperature of the battery becomes too high by connecting a cathode terminal of the bare cell to an anode terminal by a lead plate of a conducting material, or when a voltage is increased by overcharge, or when some other operational characteristic of the battery deviates excessively from its normal range of operation. 
         [0007]    A conventional battery pack may be constructed with a bare cell having an electrode terminal protruding toward one short side edge surface so as to be charged and discharged, a core pack including a protection circuit module combined with one side surface of the bare cell. A resin molded part may be formed so as to be installed on an outer set while the protection circuit module preventing from separating from the bare cell by a hot melt technique of filling hot-melt resin on an upper region of the core pack including the protection circuit module, and an outer cover covering both side parts of the core pack to form a part of the outer appearance. 
         [0008]    Conventionally, when the core pack of the lithium secondary battery was manufactured, the lead plate was included on both side surfaces of the protection circuit module so that the bare cell was coupled to the protection circuit module. The conventional lithium secondary battery includes two lead plates extending in a different direction about the protection circuit module, and a separate outer cover that covers the lead plates so that a manufacturing process of the battery pack is finished. Accordingly, manufacturing cost of a whole battery is increased by each of these features, and the number of manufacturing steps is also concomitantly increased. 
         [0009]    The outer cover was respectively arranged in both right and left directions of the battery. Therefore, a degree of freedom of a design according to the miniaturization of the battery was limited because width of the battery became longer. 
       SUMMARY OF THE INVENTION 
       [0010]    It is therefore an object of the present invention to provide an improved secondary battery and an improved process for manufacturing secondary batteries. 
         [0011]    It is another object to provide a secondary battery that can simplify the manufacturing process during an assembly of a bare cell and a protection circuit module, and that concomitantly reduces manufacturing costs. 
         [0012]    It is still another object to provide a secondary battery that can simplify a manufacturing process, and reduce manufacturing costs by restricting installation of a connecting member of a protection circuit module electrically coupled to a bare cell in one direction of the bare cell. 
         [0013]    According to another object of the present invention, there is to provide a secondary battery that can increase a degree of freedom of a design according to the miniaturization of the battery by shortening the overall width of the battery as measured in its longitudinal direction. 
         [0014]    Additional advantages, objects and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. 
         [0015]    According to one aspect of the present invention, there is provided a secondary battery, which may be constructed with a bare cell; a protection circuit module installed on one edge side surface of the bare cell; first and second electrode terminals included in the bare cell; first and second lead plates configured to electrically couple the protection circuit module to the first and second electrode terminals respectively, wherein the first and second lead plates are installed on the same single side edge surface of the bare cell. 
         [0016]    The protection circuit module may be installed on one long side edge surface of the bare cell, and the first electrode terminal may be formed on one short side edge surface neighboring to the one long side edge of the bare cell, so that the first and second lead plates are connected to the first and second electrode terminals on one short side edge. 
         [0017]    The first electrode terminal maybe formed on the short side edge surface so as to protrude toward the outside, and the second electrode terminal may be formed on the short side edge surface of the bare cell. The first and second lead plates may be installed to be spaced apart from each other, and an outer circumferential surface of the first lead plate may be coated with an insulator. 
         [0018]    The outer cover may be attached on the short side edge surface where the first and second lead plates are installed between the short edges of the bare cell. 
         [0019]    The protection circuit module may be installed on one short side edge surface of the bare cell, and the first electrode terminal may be formed on one short side edge surface of the bare cell where the protection circuit module is installed. 
         [0020]    The first electrode terminal may be formed on the short side edge surface of the bare cell so as to protrude toward the outside, and the second electrode terminal is formed on the short side edge surface of the bare cell. The first and the second lead plates are installed on one short side edge of the bare cell to be spaced apart from each other, and the outer circumferential surface of the first lead plate is coated with the insulator. 
         [0021]    The protection circuit module may be securely attached on the short side edge surface of the bare cell by an injection molded resin case. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    A more complete appreciation of the invention and many of the attendant advantages thereof, will be readily apparent as the same 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: 
           [0023]      FIG. 1  is a perspective view illustrating a secondary battery constructed as one exemplary embodiment of the present invention; 
           [0024]      FIG. 2  is a perspective view illustrating a state that a protection circuit module and an outer cover are separated from each other in  FIG. 1 ; 
           [0025]      FIG. 3  is an exploded perspective view illustrating a combined state of the protection circuit module and the outer cover shown by  FIG. 2 ; 
           [0026]      FIG. 4  is a perspective view illustrating a secondary battery according to another exemplary embodiment of the present invention; and 
           [0027]      FIG. 5  is a view illustrating a combined state of a resin molded case in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The aspects and features of the present invention and methods for achieving the aspects and features will be apparent by referring to the embodiments to be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed hereinafter, but can be implemented in diverse forms. The matters defined in the description, such as the detailed construction and elements, are nothing but specific details provided to assist those of ordinary skill in the art in a comprehensive understanding of the invention, and the present invention is only defined within the scope of the appended claims. In the entire description of the present invention, the same drawing reference numerals are used for the same elements across various figures. 
         [0029]    Turning now to the drawings, and to  FIGS. 1 through 3  collectively.  FIG. 1  is a perspective view illustrating a secondary battery constructed as one exemplary embodiment of the present invention;  FIG. 2  is a perspective view illustrating a state that a protection circuit module and an outer cover are separated from each other in  FIG. 1 ;  FIG. 3  is a perspective view illustrating a combined and assembled state of  FIG. 2 . 
         [0030]    A lithium secondary battery  500  may be constructed with a bare cell  100  formed in a rectangular shape, a protection circuit module  200  electrically coupled to bare cell  100 , an outer cover  300  covering both short side edges of the bare cell  100 , and a resin molded part  400  molded between and joining an upper region at one long side edge of bare cell  100  including a part of outer cover  300  and protection circuit module  200 . 
         [0031]    Bare cell  100  has a rectangular parallelepiped shape that has both short side edge surfaces  110  and  120  corresponding to the relatively short side surfaces with respect to front and rear surfaces  101  and  102 , and both long side edge surfaces  130  and  140  corresponding to the relatively long side surfaces. 
         [0032]    Protection circuit module  200  is arranged on one long side edge surface  130 , which forms a protection circuit substrate  210  and an outer terminal  220  installed on the protection circuit substrate  210 . 
         [0033]    Protection circuit substrate  210  may be constructed with a circuit that regulates changing of the battery in order to make the battery&#39;s charged state uniformed by controlling charge or discharge of the battery, and with a protection circuit preventing over-charge or over-discharge. Circuit element  212  is included in protection circuit substrate  210  to complete the one or more, stages forming the protection circuits. 
         [0034]    Protection circuit substrate  210  includes a first lead plate  230  coupling protection circuit module  200  to an electrode terminal  150  formed on the short side edge surface of bare cell  100  so as to be protruded, and a second lead plate  240  coupling protection circuit module  200  to an opposite polarity to electrode terminal  150 . In this embodiment, first and second lead plates  230  and  240  are installed on the same short side edge surface  110  of bare cell  100 . 
         [0035]    In both short side edge surfaces  110  and  120  neighboring long side edge surface  130  where protection circuit module  200  is installed, first lead plate  230  and second lead plate  240  are installed on short side edge surface  110  where electrode terminal  150  is formed so as to protrude toward the outside and away from surface  110 . In first and second lead plates  230  and  240  installed on short side edge surface  110  of bare cell  100 , first lead plate  230  is connected to electrode terminal  150 , and second lead plate  240  is connected to short side edge surface  110  of bare cell  100  in a state of being surface-contacted. Second lead plate  240  electrically connects an opposite polarity to electrode terminal  150 , because an outer circumferential surface of bare cell  100  including short side edge surface  110  of bare cell  100  has a polarity opposite to electrode terminal. 
         [0036]    As first second lead plates  230  and  240  are installed so as to be spaced apart from each other by a predetermined distance, an electrical short which cold be created due to a contact formed between the lead plates can be prevented. 
         [0037]    Except for a region where first lead plate  230  is connected to electrode terminal  150 , and a region where second lead plate  240  is coupled to bare cell  100 , the other regions are coated with an electrical insulator so as to prevent the occurrence of an electrical short circuit, even when the lead plates are in contact with each other. 
         [0038]    When second lead plate  240  is connected to short side edge surface  110  of bare cell  100 , at least first lead plate  230  is coated with a layer of the electrical insulator so as to be insulated from short side edge surface  110  of bare cell  100 . When first lead plate  230  is not insulated, it can be connected to electrode terminal  150  so as to be spaced apart from short side edge surface  110  of bare cell  100  without forming an electrical contact with short side edge surface  110  of bare cell  100 . 
         [0039]    First and second lead plates  230  and  240  are respectively electrically connected to short side edge surface  110  where electrode terminal  150  is installed, to short side edge surface  110  neighboring protection circuit module  200  installed on long side edge surface  130  of bare cell  100 . Thus, a separate outer cover need not be installed on short side edge surface  120  opposite to short side edge surface  110 . 
         [0040]      FIGS. 4 and 5  are perspective views illustrating separated and combined states of a secondary battery case constructed as another exemplary embodiment of the principles of the present invention. 
         [0041]    Referring to  FIGS. 4 and 5 , protection circuit module  200  is installed on short side edge surface  110  of bare cell  100  in secondary battery  700  in the construction of another exemplary embodiment of the present invention. In other words, when protection circuit module  200  of a horizontal type may be installed in one exemplary embodiment of the present invention, protection circuit module  200  of a vertical type is installed in another exemplary embodiment of the present invention. 
         [0042]    First and second lead plates  230  and  240  are installed on short side edge surface  110  of bare cell  100  with protection circuit module  200  so as to electrically couple bare cell  100  to protection circuit module  200  in another exemplary embodiment of the present invention. 
         [0043]    As a result, first lead plate  230  is connected to electrode terminal  150  on short side edge surface  110  where protection circuit module  200  is installed, and second lead plate  240  is connected to short side edge surface of bare cell  100  in a surface-contact state. 
         [0044]    First and second lead plates  230  and  240  are installed so as to be spaced apart from each other by a predetermined distance. Thus, an electrical short circuit due to a contact between the lead plates can be prevented. 
         [0045]    When lead plates  230  and  240  are in electrical contact with each other, with the outer circumferential surface of the other regions of lead plates  230 ,  240  except for a connecting region that lies between first lead plate  230  and second lead plate  240  being coated with an insulator so as to prevent the occurrence of an electrical short circuit. 
         [0046]    The outer circumferential surface of first lead plate  230  should be formed to be electrically insulated. If first lead plate  230  is not electrically insulated, lead plate  230  should be connected to electrode  150  without being in electrical contact with short side edge surface  110  of bare cell  100 . Accordingly, it is not necessary that a separate washer of an insulating material should be installed on short side edge surface  110  of bare cell  100 . 
         [0047]    Protection circuit module  200  can be molded and attached to bare cell  100  by hot melt resin, but protection circuit module  200  is securely attached and is fixed by a previously molded resin case  600  in another exemplary embodiment of the present invention. In this particular embodiment, although not shown in the drawings, protection circuit module  200  is pre-assembled to a locked state so as to be integral with molded resin case  600 , and then assembled on one side end of bare cell  100 . After first and second lead plates  230  and  240  which extend outwardly from protection circuit module  200  are resistance-welded on electrode terminal  150  and short side edge surface  110  of bare cell  100 , molded resin case  600  is assembled by a technique of covering one end of the upper part of short side edge surface  110  of bare cell  100 , as shown in  FIG. 5 . 
         [0048]    First and second lead plates  230  and  240  are installed together on short side edge surface  110  of bare cell  100  in another exemplary embodiment of the present invention, so that first and second lead plates  230  and  240  are covered by molded resin case  600  when combining protection circuit module  200  with bare cell  100 , thereby allowing the outer cover to be safely eliminated. 
         [0049]    As described above, the secondary battery according to the present invention produces the following beneficial results and advantageous results. 
         [0050]    The connecting member of the protection circuit module electrically coupled to the bare cell may be conveniently installed on the same surface in one direction of the bare cell, thereby allowing the manufacturing process of the secondary battery to be simplified and the manufacturing cost of the secondary battery to be reduced. 
         [0051]    The width of the battery is reduced in the longitudinal direction, thereby allowing a substantial increase in the degree of freedom for the design of the battery, and thus allowing further miniaturization of the battery. 
         [0052]    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 is 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 limitations of the invention.