Abstract:
A secondary battery module including a plurality of unit batteries that each include a cap plate and a case connected to either one of a positive electrode and a negative electrode of an electrode assembly and an electrode terminal connected to the other of the positive electrode and negative electrode, wherein the electrode terminal protrudes outside of a unit battery by passing through the cap plate covering the case, and a connector having a first end and a second end, wherein the first end fits on the electrode terminal of one of the unit batteries and is screw-engaged to the electrode terminal by a nut and the second end is connected to the case of another adjacent unit battery.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    Embodiments relate to a secondary battery module, and more particularly, to a secondary battery module that enhances a structure of a connector for electrically connecting unit batteries and an arrangement of the unit batteries. 
         [0003]    2. Description of the Related Art 
         [0004]    Rechargeable batteries may be repeatedly charged and discharged, unlike primary batteries that cannot be repeatedly charged. Low-capacity rechargeable batteries may be used for portable compact electronic apparatuses, e.g., mobile phones, notebook computers and camcorders, and high-capacity rechargeable batteries may be used as a power source for, e.g., driving a motor of a hybrid vehicle, etc. 
         [0005]    Recently, a high-output rechargeable battery using a non-aqueous electrolyte having high energy density has been developed. The high-output rechargeable battery may be configured with high capacity by, e.g., connecting a plurality of unit rechargeable batteries in series so as to be used for driving a motor for an apparatus requiring a large amount of power, e.g., an electric vehicle, etc. 
         [0006]    For example, a secondary battery module may be formed by connecting a plurality of rechargeable batteries, i.e., the unit batteries, in series. The unit batteries may have, e.g., a cylindrical shape, a prismatic shape, etc. 
         [0007]    The unit battery may include an electrode assembly formed of a positive electrode and a negative electrode with a separator interposed therebetween, a case incorporating the electrode assembly, a cap plate sealing the case and electrode terminals that are electrically connected to the electrode assembly and protrude out of the cap plate. 
         [0008]    For example, the electrode terminal may include a positive terminal and a negative terminal that are connected to the positive electrode and the negative electrode of the electrode assembly, respectively. Since the secondary battery module may have a barrier rib formed between the unit batteries, the secondary battery module may radiate heat through a surface of the case and the barrier rib. 
         [0009]    Positive terminals and negative terminals of adjacent unit batteries may be electrically connected to each other by a bus bar. 
         [0010]    Each secondary battery module may include the positive terminal and the negative terminal and may have a disadvantage of making a connection structure of the unit batteries and an arrangement of the unit batteries difficult by connecting the positive terminal and the negative terminal to each other by using the bus bar. 
       SUMMARY 
       [0011]    Embodiments are therefore directed to a secondary battery module, which substantially overcomes the problems due to the limitations and disadvantages of the related art. 
         [0012]    It is therefore a feature of an embodiment to provide a secondary battery module having a simplified structure of connectors for electrically connecting unit batteries and an arrangement of the unit batteries. 
         [0013]    At least one of the above and other features and advantages may be realized by providing a secondary battery module, including a plurality of unit batteries that each include a cap plate and a case connected to either one of a positive electrode and a negative electrode of an electrode assembly and an electrode terminal connected to the other of the positive electrode and negative electrode, wherein the electrode terminal protrudes outside of a unit battery by passing through the cap plate covering the case, and a connector having a first end and a second end, wherein the first end fits on the electrode terminal of one of the unit batteries and is screw-engaged to the electrode terminal by a nut and the second end is connected to the case of another adjacent unit battery. 
         [0014]    The case may include a plurality of ribs on one side thereof so as to form a flow passage of a heat transfer medium between the unit batteries adjacent to each other. 
         [0015]    The ribs may extend in a vertical direction and may be arranged at a predetermined interval in a horizontal direction substantially orthogonal to the vertical direction. 
         [0016]    The case may include a plate part and a rib part, wherein the plate part may be adjacent to the electrode terminal and does not include the ribs, and the rib part may be below the plate part and includes the ribs. 
         [0017]    The case and the ribs may be a monolithic injection-molded unit. 
         [0018]    The connector may include a horizontal part having a through-hole coupled to the electrode terminal of one of the unit batteries and a vertical part bent substantially perpendicular to the horizontal part and welded to the side of the case of an adjacent unit battery. 
         [0019]    The horizontal part may have a length from the center of the electrode terminal equal to at least about a sum of ½ the width of the unit battery plus the width of the ribs between a unit battery and another adjacent unit battery. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The above and other features and advantages will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
           [0021]      FIG. 1  illustrates a partial perspective view of a secondary battery module according to an embodiment; 
           [0022]      FIG. 2  illustrates a plan view of the secondary battery module shown in  FIG. 1 ; 
           [0023]      FIG. 3  illustrates a cross-sectional view taken along line of  FIG. 1 ; 
           [0024]      FIG. 4  illustrates an exploded perspective view of an electrode terminal and a connector; 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Korean Patent Application No. 10-2008-0131355, filed on Dec. 22, 2008, in the Korean Intellectual Property Office, and entitled: “Secondary Battery Module,” is incorporated by reference herein in its entirety. 
         [0026]    Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0027]    In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
         [0028]    As used herein, the expressions “at least one,” “one or more,” and “and/or” are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B, and C,” “at least one of A, B, or C,” “one or more of A, B, and C,” “one or more of A, B, or C” and “A, B, and/or C” includes the following meanings: A alone; B alone; C alone; both A and B together; both A and C together; both B and C together; and all three of A, B, and C together. Further, these expressions are open-ended, unless expressly designated to the contrary by their combination with the term “consisting of:” For example, the expression “at least one of A, B, and C” may also include an n th  member, where n is greater than 3, whereas the expression “at least one selected from the group consisting of A, B, and C” does not. 
         [0029]    As used herein, the expression “or” is not an “exclusive or” unless it is used in conjunction with the term “either.” For example, the expression “A, B, or C” includes A alone; B alone; C alone; both A and B together; both A and C together; both B and C together; and all three of A, B, and C together, whereas the expression “either A, B, or C” means one of A alone, B alone, and C alone, and does not mean any of both A and B together; both A and C together; both B and C together; and all three of A, B, and C together. 
         [0030]    As used herein, the terms “a” and “an” are open terms that may be used in conjunction with singular items or with plural items. For example, the term “a metal” may represent a single compound, e.g., aluminum, or multiple compounds in combination, e.g., aluminum mixed with iron. 
         [0031]    According to an embodiment, unit batteries may be arranged adjacent to each other in a way in which a case may be connected to a positive electrode of an electrode assembly and an electrode terminal may be connected to a negative electrode of the electrode assembly and in which one side of a connector may be fixed to the electrode terminal and the other side may be welded to the case, thereby simplifying the structure of the connector and arrangement of the unit batteries. Accordingly, an electrical connection structure of unit batteries and a structure of a secondary battery module may be simplified. 
         [0032]      FIG. 1  illustrates a partial perspective view of a secondary battery module according to an embodiment and  FIG. 2  illustrates a plan view of the secondary battery module shown in  FIG. 1 . 
         [0033]    Referring to  FIGS. 1 and 2 , a secondary battery module  100  may include a plurality of unit batteries  10 , and may have a high-capacity structure by connecting adjacent unit batteries  10  in series by means of connectors  20 . 
         [0034]      FIG. 3  illustrates a cross-sectional view taken along line of  FIG. 1 . Referring to  FIG. 3 , the unit battery  10  may include an electrode assembly  11 , a case  12 , a cap plate  13  and an electrode terminal  14 . 
         [0035]    The electrode assembly  11  may include a positive electrode and a negative electrode on respective surfaces of a separator interposed therebetween. For convenience, the electrode assembly  11  may be connected to a positive electrode lead member  111  and a negative electrode lead member  112  that may be connected to the positive electrode and the negative electrode, respectively, as shown in  FIG. 3 . 
         [0036]    The case  12  may incorporate the electrode assembly  11  therein by forming a space. The cap plate  13  may be joined to the case  12  and may seal the case  12  incorporating the electrode assembly  11 . An electrode terminal  14  may protrude to the outside of the cap plate  13 . The electrode terminal  14  may be insulated from the cap plate  13 . 
         [0037]    In the electrode assembly  11 , the positive electrode may be connected to the case  12  and the negative electrode may be connected to the electrode terminal  14 . Therefore, the case  12  may serve as a positive terminal and the electrode terminal  14  may serve as a negative terminal. Alternatively, in the electrode assembly, the negative electrode may be connected to the case and the positive electrode may be connected to the electrode terminal. 
         [0038]    Embodiments relate to a structure in which the unit batteries  10  are connected to each other in series. Since an embodiment may adopt various electrode assemblies  11 , a detailed description of the electrode assembly  11  will be omitted. 
         [0039]    The case  12  may include a conductive metal, e.g., aluminum, an aluminum alloy, or nickel-plated steel, and may have, e.g., a hexahedral prismatic shape or other shapes, so as to have an inner space where the electrode assembly  11  may be positioned. 
         [0040]    The case  12  may include ribs  121  at one side thereof. The case  12  and the ribs  121  may be integrally fabricated by, e.g., injection molding, such that it may be possible to minimize costs while improving heat radiating performance of the unit batteries  10 . 
         [0041]    The ribs  121  may provide a flow passage of a heat transfer medium between the unit batteries  10  disposed adjacent to each other, i.e., between adjacent cases  12 , to effectively radiate heat of the unit batteries  10  together with the case  12 . 
         [0042]    Referring back to  FIG. 1 , the ribs  121  may extend in a vertical direction and may be arranged at a predetermined interval C in a horizontal direction substantially orthogonal to the vertical direction. Thus, the intervals C between the adjacent cases  12  and between the ribs  121  may restrict the flow passage. 
         [0043]    Further, the ribs  121  may be formed on the entire surface of the one side of the case  12  (not shown), but alternatively the ribs  121  may be formed on only a part of the one side. 
         [0044]    Thus, the case  12  may include a plate part  122  and a rib part  123  that are partitioned depending on formation of the ribs  121 . The plate part  122  may be disposed in an upper part adjacent to the electrode terminal  14 , and may not have the ribs  121 . The rib part  123  may be disposed in a lower part of the plate part  122 , and may have the ribs  121 . 
         [0045]    Since the ribs  121  may be formed at one side of the case  12  and may not be formed at the other side of the case  12 , the unit batteries  10  may be alternately disposed such that the interval C between the ribs  121  may be formed between the unit batteries  10 . That is, the flow passage having the interval C may be formed between the unit batteries  10 . 
         [0046]    The cap plate  13  may seal an opening at one side of the case  12 , and the electrode terminal  14  may protrude at the center of the cap plate  13 . In the unit battery  10  of an embodiment, since the case  12  may be connected to the positive electrode to serve as the positive terminal, only one electrode terminal  14  connected to the negative electrode may protrude outside of the cap plate  13 . The electrode terminal  14  may be insulated from the cap plate  13 . 
         [0047]    Thus, the unit batteries  10  may be connected with each other in series by connecting the case  12  of one unit battery with the electrode terminal  14  of another adjacent unit battery. As a result, the connection structure of the unit batteries  10  and the arrangement of the unit batteries  10  may be simplified. 
         [0048]      FIG. 4  illustrates an exploded perspective view of an electrode terminal and a connector. Referring to  FIG. 4 , each connector  20  may be configured to connect adjacent unit batteries  10  in series. 
         [0049]    Thus, one end of the connector  20  may be fixed to the electrode terminal  14  by a nut  141  that may be screw-engaged in the electrode terminal  14 , and the other end of the connector  20  may be connected to the case  12  by being, e.g., welded to the case  12 . The connector  20  that is fixed to the electrode terminal  14  of one unit battery  10  may be connected to the side of the case of another unit battery  10  at which the ribs  121  are not formed. 
         [0050]    More specifically, the connector  20  may include a horizontal part  21  fixed to the electrode terminal  14  and a vertical part  22  connected to the case  12 . 
         [0051]    The horizontal part  21  may be substantially parallel to the cap plate  13 , and may have a through-hole  211  in which the electrode terminal  14  may be inserted and may be fixed to the electrode terminal  14  by screw-engaging the nut  141  to the electrode terminal  14 . 
         [0052]    The vertical part  22  may be bent in a vertical direction with respect to the horizontal direction  21  and welded to the side of the case  12  of an adjacent unit battery. As such, the electrode terminal  14  of one of the unit batteries and the case  12  of an adjacent unit battery may be connected with each other through the connector  20  that includes the horizontal part  21  and the vertical part  22 , thereby simplifying the connection structure of the unit batteries  10 . 
         [0053]    The horizontal part  21  may have a length from the center of the electrode terminal  14  that is equal to at least a sum CW/2+RW, where CW/2 is ½ of the overall width CW of the unit battery  10  (to the center of the electrode terminal  14 ) and RW is the width of the ribs  121  formed at one side of the case  12  of each unit battery  10 . 
         [0054]    Therefore, by the size of the horizontal part  21 , in a state in which the horizontal part  21  of the connector  20  is fixed to the electrode terminal  14  and the vertical part  22  is welded to the case  12 , unnecessary stress may not be applied between adjacent unit batteries  10  connected to the connector  20 . 
         [0055]    Further, since the connector  20  may be exposed to an upper part of a flow passage by the rib  121 , the connector  20  may be effectively cooled by flow of the heat transfer medium; and the electrode terminal  14  that is connected to the connector  20  may also be subjected to a cooling effect achieved by the flow of the heat transfer medium. 
         [0056]    Exemplary embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.