Abstract:
A battery pack including: a plurality of secondary batteries, each including an electrode terminal having a cooling groove; a cooling pipe configured to pass a heat transfer medium therethrough, the cooling pipe being received in the cooling groove of each of the plurality of secondary batteries; and a bus bar electrically connecting the electrode terminals of adjacent secondary batteries of the plurality of secondary batteries.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2012-0041112, filed on Apr. 19, 2012 in the Korean intellectual Property Office, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Aspects of embodiments of the present invention relate to a battery pack. 
     2. Description of the Related Art 
     Generally, secondary batteries may be charged and discharged. One secondary battery is typically used in small portable devices such as cellular phones, notebooks, computers, cameras, and camcorders. Also, a battery pack including a plurality of secondary batteries connected to each other is mainly used as a power source for driving a motor, such as a motor of a high-output hybrid electric vehicle (HEV) or an electric vehicle (EV). 
     Since secondary batteries that are several or several tens of unit cells are connected to each other to constitute one battery pack, a cooling structure, a safety unit, and a system circuit which are configured to easily dissipate heat generated in the battery pack may be provided. In particular, since high-output, high-capacity battery packs for HEVs and EVs demand high output, battery packs having improved thermal performance for dissipating large amounts of heat are required. 
     SUMMARY 
     According to an aspect of embodiments of the present invention, a battery pack includes a cooling pipe received in an electrode terminal to directly cool the electrode terminal, thereby improving thermal performance when a high-capacity reaction occurs. 
     According to another aspect of embodiments of the present invention, a battery pack includes a cooling pipe received in an electrode terminal to directly cool the electrode terminal, thereby reducing thermal deformation and improving durability. 
     As such, a rechargeable battery according to embodiments of the present invention is suited for application in an electric vehicle or a hybrid electric vehicle. 
     According to an embodiment of the present invention, a battery pack includes: a plurality of secondary batteries, each including an electrode terminal having a cooling groove; a cooling pipe configured to pass a heat transfer medium therethrough, the cooling pipe being received in the cooling groove of each of the plurality of secondary batteries; and a bus bar electrically connecting the electrode terminals of adjacent secondary batteries of the plurality of secondary batteries. 
     The cooling groove may have a substantially straight shape and may be formed having a depth in a surface of the electrode terminal. 
     The bus bar may be bonded to the surface of the electrode terminal and may cover the cooling pipe. 
     The cooling pipe may be received in the cooling groove of each of the plurality of secondary batteries and integrated with the secondary batteries. 
     Each of the plurality of secondary batteries may include: an electrode assembly including a first electrode plate and a second electrode plate; the electrode terminal having the terminal including a first electrode terminal electrically connected to the first electrode plate of the electrode assembly and having a first cooling groove, and a second electrode terminal electrically connected to the second electrode plate of the electrode assembly and having a second cooling groove; a case receiving the electrode assembly therein and having an opening; and a cap plate from which the first and second terminals protrude, the cap plate sealing the opening of the case in which the electrode assembly is received. 
     The first cooling groove of the first electrode terminal may be formed in a surface of the first electrode terminal to have a first angle with respect to a lengthwise direction of the cap plate. 
     The second cooling groove of the second electrode terminal may be formed in a surface of the second electrode terminal to have a second angle with respect to the lengthwise direction of the cap plate. 
     The first and second cooling grooves may be substantially perpendicular to the lengthwise direction of the cap plate. 
     Each of the first and second cooling grooves may include two substantially straight grooves, and the two grooves may be substantially parallel to each other. 
     In the plurality of secondary batteries, the first cooling groove may extend in a same substantially straight line as the second cooling groove of the adjacent secondary battery, and the second cooling groove may extend in a same substantially straight line as the first cooling groove of another adjacent secondary battery of the plurality of secondary batteries. 
     The cooling pipe may include ring-shaped pipes respectively received in the first and second cooling grooves formed in the same substantially straight line in the plurality of secondary batteries; and a straight pipe connecting the ring-shaped pipes to each other, and the cooling pipe may be configured to pass the heat transfer medium therethrough to cool the first and second electrode terminals, and the ring-shaped pipes and the straight pipe may be integrated with each other. 
     Both sides facing each other of each of the ring-shaped pipes may be received in one of the first or second cooling grooves. 
     In the plurality of secondary batteries, the cooling pipe may be an integrated pipe received in the first and second cooling grooves extending in the same line. 
     The cooling pipe may have a “U” shape and may be received in the first and second cooling grooves extending in the same line to provide a circulation passage of the heat transfer medium to cool the first and second electrode terminals. 
     In the plurality of secondary batteries, the first electrode terminal of one of the adjacent secondary batteries may be electrically connected to the second electrode terminal of the other of the adjacent secondary batteries through the bus bar, and the second electrode terminal of the one of the adjacent secondary batteries may be electrically connected to the first electrode terminal of another adjacent secondary battery of the plurality of secondary batteries through another bus bar. 
     The first and second electrode terminals may be arranged to cross the second and first electrode terminals, respectively, of the adjacent secondary battery to form two terminal rows. 
     The cooling pipe may include two cooling pipes, and the two cooling pipes may be respectively received in the cooling grooves of the first and second electrode terminals in the same terminal row of the two terminal rows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate some exemplary embodiments of the present disclosure and, together with the description, serve to explain aspects and principles of the present invention. In the drawings: 
         FIGS. 1A and 1B  are perspective and partially exploded perspective views, respectively, of a battery pack according to an embodiment of the present invention; 
         FIG. 2  is a perspective view of a secondary battery of the battery pack of  FIGS. 1A and 1B ; 
         FIG. 3  is a partially exploded perspective view of a battery pack according to another embodiment of the present invention; and 
         FIG. 4  is an enlarged view of a cooling pipe of the battery pack of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, certain exemplary embodiments of the present invention are shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals denote like elements throughout. 
       FIGS. 1A and 1B  are perspective and partially exploded perspective views, respectively, of a battery pack according to an embodiment of the present invention.  FIG. 2  is a perspective view of a secondary battery of the battery pack of  FIGS. 1A and 1B . The battery pack of  FIGS. 1A and 1B  is described below with reference to the secondary battery of  FIG. 2 . 
     Referring to  FIGS. 1A and 1B , a battery pack  100  includes a plurality of secondary batteries  110 , a cooling pipe  120 , and one or more bus bars  130 . Although the battery pack  100  is illustrated in  FIGS. 1A and 1B  including four of the secondary batteries  110 , the present invention is not limited thereto. For example, the number of the secondary batteries  110  may be varied according to a desired capacity and use of the battery pack  100 . 
     Referring to  FIG. 2A , in one embodiment, each of the secondary batteries  110  includes an electrode assembly  111  in which a first electrode plate and a second electrode plate are stacked or wound with a separator therebetween, a case  112  receiving the electrode assembly  111  therein and having an upper end opening, a cap plate  113  sealing the upper end opening of the case  112 , and first and second electrode terminals  114  and  115  electrically connected to the first electrode plate and the second electrode plate, respectively, and protruding outward from the cap plate  113 . 
     The electrode assembly  111  and electrolyte are received in the case  112 . The electrolyte may include an organic solvent such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), or dimethyl carbonate (DMC), and a lithium salt such as LiPF6 or LiBF4. The electrolyte may be a liquid, solid, or gel. 
     The case  112  may be formed of a conductive metal, such as aluminum, aluminum alloy, or steel plated with nickel. The case  112 , in one embodiment, may have a hexahedral shape in which the electrode assembly  111  is housed in an inner space thereof, or any other suitable shape. 
     The cap plate  113  is coupled to the case  112  to cover the upper end opening of the case  112  after the electrode assembly  111  is contained in the inner space of the case  112 . In one embodiment, holes through which the first and second electrode terminals  114  and  115  protrude upward from the cap plate  113  are defined in the cap plate  113 . A gasket  113   a  may be disposed between each of the holes of the cap plate  113  and the respective first and second electrode terminals  114  and  115 . 
     In one embodiment, the first electrode terminal  114  is electrically connected to the first electrode plate of the electrode assembly  111 , and the second electrode terminal  115  is electrically connected to the second electrode plate of the electrode assembly  111 . The first and second electrode terminals  114  and  115  may be electrode terminals which have polarities different from each other. 
     In one embodiment, each of the first and second electrode terminals  114  and  115  may have a square pillar shape. Also, the first and second electrode terminals  114  and  115  may protrude with a same height. The first and second electrode terminals  114  and  115  of the secondary battery may protrude upward from the cap plate  113  in a state in which the first and second electrode terminals  114  and  115  are spaced apart from each other by a distance (e.g., a predetermined distance). 
     Each of the first and second electrode terminals  114  and  115  may protrude upward from the cap plate  113  through the respective gasket  113   a  of the cap plate  113 . The gasket  113   a  may be formed of an insulative material. Thus, the first and second electrode terminals  114  and  115  may be electrically insulated from the cap plate  113 . 
     The electrode terminals  114  and  115  have cooling grooves  114   a  and  115   a , each having a depth (e.g., a predetermined depth) from a top surface thereof, respectively. The cooling grooves  114   a  and  115   a , in one embodiment, include a first cooling groove  114   a  defined in the first electrode terminal  114 , and a second cooling groove  115   a  defined in the second electrode terminal  115 . 
     In one embodiment, each of the first and second cooling grooves  114   a  and  115   a  may be a straight or substantially straight groove having an angle (e.g., a predetermined angle) with respect to a lengthwise direction of the cap plate  113 . The first and second cooling grooves  114   a  and  115   a  are defined in the first and second electrode terminals  114  and  115 , respectively. In one embodiment, the first and second cooling grooves  114   a  and  115   a  may be perpendicular or substantially perpendicular to the lengthwise direction of the cap plate  113 . In one embodiment, the first and second cooling grooves  114   a  and  115   a  may be symmetric to each other with respect to a center of the cap plate  113  along the lengthwise direction. 
     In one embodiment, the first cooling groove  114   a  passes between one surface and the other surface of the first electrode terminal  114  parallel or substantially parallel to the lengthwise direction of the cap plate  113 . That is, the first cooling groove  114   a  may extend from the one surface of the first electrode terminal  114  to an opposite surface of the first electrode terminal  114  in a direction crossing (e.g., perpendicular to) the lengthwise direction of the cap plate  113 . In one embodiment, the first cooling groove  114   a  may include two grooves, each having a straight or substantially straight shape. The two grooves may be defined in a top surface of the first electrode terminal  114  parallel or substantially parallel to each other. In another embodiment, each of the first and second cooling grooves  114   a  and  115   a  may be provided as one groove. 
     In one embodiment, the second cooling groove  115   a  may have the same shape as that of the first cooling groove  114   a . The second cooling groove  115   a  may be defined between one surface and the other surface of the second electrode terminal  115  parallel or substantially parallel to the lengthwise direction of the cap plate  113  to pass through the second electrode terminal  115 . That is, the second cooling groove  115   a  may extend from the one surface of the second electrode terminal  115  to an opposite surface of the second electrode terminal  115  in a direction crossing (e.g., perpendicular to) the lengthwise direction of the cap plate  113 . In one embodiment, the second cooling groove  115   a  may include two grooves, each having a straight or substantially straight shape. The two grooves may be defined in a top surface of the second electrode terminal  115  parallel or substantially parallel to each other. 
     The plurality of secondary batteries  110  having a same or similar structure are arranged so that side surfaces of the secondary batteries  110  in a lengthwise direction face each other in a state in which the electrode terminals  114  and  115  face an upper side. Each of the side surfaces of each of the secondary batteries  110  in the lengthwise direction may be a surface having a relatively wide area of the side surfaces of the secondary battery  110  when a surface on which the electrode terminals  114  and  115  is defined as a top surface. That is, the relatively wide side surfaces of the secondary batteries  110  may be arranged to face each other. 
     In the plurality of secondary batteries  110 , the first and second electrode terminals  114  and  115  are alternately arranged on both sides of the secondary batteries  110  with respect to a center of the lengthwise direction of the cap plate  113 . The lengthwise direction of the cap plate  113  may be a direction in which the cap plate  113  has a relatively long length, 
     The first and second electrode terminals  114  and  115  of each of the plurality of secondary batteries  110  and the first and second electrode terminals  114  and  115  of the adjacent secondary battery  110  are alternately arranged to cross each other, thereby forming terminal rows. Each of the terminal rows may be a line in which the terminals having polarities different from each other are arranged in the line. That is, the plurality of secondary batteries  110  are arranged to form two terminal rows. In one embodiment, the cooling grooves  114   a  and  115   a  of the first and second electrode terminals  114  and  115  of the same terminal row are arranged in the same straight line. In one embodiment, each of the cooling grooves  114   a  and  115   a  includes two grooves parallel to each other, and the cooling grooves  114   a  and  115   a  in the same terminal row are arranged in two straight lines parallel to each other. 
     In the battery pack  100  according to one embodiment, the cooling pipe  120  may be an integrated pipe received in each of the cooling grooves  114   a  and  115   a  which are defined in the same straight line. In one embodiment, two cooling pipes  120  may be provided. Here, the two cooling pipes  120  may be received in the cooling grooves  114   a  and  115   a  of the first and second electrode terminals  114  and  115  arranged in the same terminal row of the two terminal rows, respectively. 
     The cooling pipe  120  may be a circulation passage of a heat transfer medium, such as a coolant for cooling the plurality of secondary batteries  110 . In one embodiment, the cooling pipe  120  may have a “U” shape. The two sides of the cooling pipe  120  having the “U” shape may be received in the cooling groove defined in two straight lines within the same terminal row, respectively. The cooling pipe  120  may have an end  120   a  connected to a circulation pump (not shown), and the heat transfer medium may be circulated through the inside of the cooling pipe  120  by the circulation pump. 
     The cooling pipe  120  may include at least one of a plastic pipe, an insulated pipe, or a conductive pipe having high thermal conductivity coated with an insulative material on an outer surface thereof. Since the cooling pipe  120  having the high thermal conductivity can directly cool the first and second electrode terminals  114  and  115  of the plurality of secondary batteries  110  by the coolant circulated in the cooling pipe  120 , thermal performance may be improved when a high-output reaction occurs. As described above, since the cooling pipe  120  is disposed in the electrode terminals  114  and  115  to directly cool the first and second electrode terminals  114  and  115 , thermal deformation may be reduced and durability may be improved. 
     In one embodiment, the bus bar  130  is bonded to the top surfaces of the first and second electrode terminals  114  and  115  to cover the first and second electrode terminals  114  and  115  in which the cooling pipe  120  is received in the cooling grooves  114   a  and  115   a . The bus bar  130  may have a plate structure having a generally rectangular shape or a plate structure having a generally bar shape. 
     The bus bar  130  electrically connects the first electrode terminals  114  of the plurality of secondary batteries  110  to the second electrode terminal  115  of the adjacent secondary battery  10  arranged in the same terminal row. Also, the bus bar  130  electrically connects the second electrode terminals  115  of the plurality of secondary batteries  110  to the first electrode terminal  114  of the adjacent secondary battery  110  arranged in the same terminal row. 
     In one embodiment, the bus bar  130  may be welded to the top surfaces of the first and second electrode terminals  114  and  115  such that the first and second electrode terminals  114  and  115  of the plurality of secondary batteries  110  are disposed to cross the electrode terminals  114  and  115  of the adjacent secondary battery  110 . Here, the bus bar  130  having the plate structure may have a flat surface welded to the top surfaces of the first and second electrode terminals  114  and  115 . That is, the plurality of secondary batteries  110  may be connected to each other in series by one or more of the bus bars  130  to form the battery pack  100  having high capacity. 
       FIG. 3  is a partially exploded perspective view of a battery pack according to another embodiment of the present invention. 
     Referring to  FIG. 3 , a plurality of the secondary batteries  110  and one or more of the bus bars  130  of a battery pack  200  may have the same or similar structure as those of the battery pack  100  described above with respect to  FIGS. 1A and 1B .  FIG. 4  is an enlarged view of a cooling pipe of the battery pack  200  of  FIG. 3  that is different from the cooling pipe  120  of the battery pack  100  described above with respect to  FIGS. 1A and 1B . A cooling pipe  220  of the battery pack  200  different from the cooling pipe  120  of the battery pack  100  is described below with reference to  FIGS. 3 and 4 . 
     The cooling pipe  220  according to an embodiment of the present invention includes ring-shaped pipes  221  (e.g., square ring-shaped pipes) and straight pipes  222 . The ring-shaped pipes  221  are received in each of cooling grooves  114  and  115  defined in the first and second electrode terminals  114  and  115 . The straight pipes  222  connect the adjacent ring-shaped pipes  221  to each other. That is, the straight pipes  222  connect the ring-shaped pipes  221  received in the cooling grooves  114   a  and  115   a  of the first and second electrode terminals  114  and  115  of the same terminal row to each other. 
     The ring-shaped pipes  221  and the straight pipes  222 , in one embodiment, are integrated with each other to provide a circulation passage of a heat transfer medium, such as a coolant for cooling the plurality of secondary batteries  110 . The cooling pipe  220  may have an end  220   a  connected to a circulation pump (not shown), and the heat transfer medium may be circulated through the inside of the cooling pipe  220  by the circulation pump. In one embodiment, the cooling pipe  220  may be an integrated pipe received in the cooling grooves  114   a  and  115   a  defined in the same straight line in the plurality of secondary batteries  110 . In one embodiment, two cooling pipes  220  may be provided. The two cooling pipes  220  may be received in the cooling grooves  114   a  and  115   a  of the first and second electrode terminals  114  and  115  of the same terminal row of the two terminal rows, respectively. 
     In one embodiment, the cooling pipe  220  may include at least one of a plastic pipe, an insulated pipe, or a conductive pipe having high thermal conductivity coated with an insulation material on an outer surface thereof. In one embodiment, the cooling pipe  220  having the high thermal conductivity can directly cool the first and second electrode terminals  114  and  115  of the plurality of secondary batteries  110  by the coolant circulated in the cooling pipe  220 , and thermal performance may be improved when a high-output reaction occurs. As described above, since the cooling pipe  220  is disposed in the first and second electrode terminals  114  and  115  to directly cool the first and second electrode terminals  114  and  115 , thermal deformation of the plurality of secondary batteries  110  may be reduced and durability may be improved. 
     In the battery pack according to embodiments of the present invention, since the cooling pipe is received in the electrode terminals to directly cool the electrode terminals, thermal performance may be improved, such as when a high-capacity reaction occurs. 
     Also, in the battery pack according to embodiments of the present invention, since the cooling pipe is received in the electrode terminals to directly cool the electrode terminals, thermal deformation may be reduced to improve durability. 
     While some 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 purposes 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 disclosure as set forth in the following claims and equivalents thereof.