Abstract:
A multi-cell electrochemical battery comprises a casing having an interior divided into a plurality of battery cell compartments by at least one partition, each battery cell compartment sized to receive a plurality of battery cells. A fluid circuit comprises a plurality of flow passages extending across said container through said at least one partition. Fluid inlet structure receives input fluid and delivers the input fluid to the fluid circuit. Fluid outlet structure permits the egress of fluid exiting the fluid circuit from the container. A plurality of electrochemical battery cells is accommodated in each battery cell compartment.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates generally to electrochemical batteries and in particular, to a casing for a multi-cell electrochemical battery and to a multi-cell electrochemical battery incorporating the same. 
       BACKGROUND OF THE INVENTION 
       [0002]    Rechargeable, multi-cell electrochemical batteries are becoming increasingly popular and are used in a variety of commercial and industrial applications. Depending on the application, the number of electrochemical cells and the parallel and serial interconnections of the electrochemical cells in the electrochemical batteries vary to achieve the desired battery output voltages (determined by the series connections of the electrochemical cells) and the desired battery capacity and current handling capabilities (determined by the parallel connections of the electrochemical cells). Unfortunately however, electrochemical cells are expensive. As a result, to make the use of electrochemical batteries economic, it is necessary to take steps to prolong the operating life of the electrochemical cells. 
         [0003]    One factor that has an impact on the operating life of electrochemical cells is temperature. In order to prolong the operating life of electrochemical cells, the temperature of the electrochemical cells must be controlled so that the temperature of the electrochemical cells stays within the specified operating range of the electrochemical cells. Operating the electrochemical cells outside of the specified temperature range can severely decrease the operating life of the electrochemical cells. It is therefore not surprising that techniques to provide cooling to multi-cell electrochemical batteries have been considered. 
         [0004]    For example, U.S. Pat. No. 7,264,901 to Gow et al. discloses a monoblock battery case comprising a first container and a second container each having partitions that divide the containers into cell compartments. The first container is attached to and co-operates with the second container to form one or more coolant channels disposed between the facing surfaces of the first and second containers. Outer ribs defining fluid baffles may also be provided on the opposite surfaces of the first and second containers. 
         [0005]    U.S. Pat. No. 7,547,487 to Smith et al. discloses a multi-cell battery in which a plurality of electrochemical cells are disposed in a battery case. The battery case includes one or more partitions which divide the interior of the case into a plurality of cell compartments that house the electrochemical cells. One or more of the partitions include coolant channels. The bottom of the casing includes ribs that define fluid baffles for fluid flow purposes. Coolant enters the bottom plate via an inlet opening adjacent one end of the bottom plate, travels along flow channels to defined by the ribs and through coolant channels in the partitions before exiting the bottom plate via an outlet opening adjacent the opposite end of the bottom plate. 
         [0006]    Although cooling techniques for multi-cell electrochemical batteries exist, improvements are desired. It is therefore an object of the present invention to provide a novel casing for a multi-cell electrochemical battery and a novel multi-cell electrochemical battery incorporating the same. 
       SUMMARY OF THE INVENTION 
       [0007]    Accordingly, in one aspect there is provided a casing for a multi-cell battery comprising: a container comprising a bottom, opposite major sides and opposite minor sides, the interior of the container being divided into a plurality of battery cell compartments by at least one partition extending between the opposite major sides, each battery cell compartment sized to receive a plurality of battery cells; a fluid circuit comprising a plurality of flow passages extending through said at least one partition between the opposite major sides; fluid inlet structure to receive input fluid and deliver said input fluid to said fluid circuit; and fluid outlet structure to permit the egress of fluid exiting said fluid circuit from said container. 
         [0008]    In one embodiment, the container is divided into a plurality of battery cell compartments by a plurality of spaced partitions. In this case, the fluid circuit comprises a plurality of spaced flow passages extending through each partition. The fluid circuit also comprises a plurality of spaced flow passages extending through each of the minor sides. The flow passages extending through each partition and each minor side are generally parallel and are generally evenly spaced. 
         [0009]    In one embodiment, each battery cell compartment is sized to receive the same number of battery cells. In one embodiment, a plurality of fluid chambers is provided adjacent each major side of the container with each fluid chamber communicating with at least two sets of fluid passages. The fluid chambers and fluid passages are arranged so that fluid delivered to the fluid inlet structure initially flows through the flow passages in one of the minor sides, then through each partition in succession via the flow passages therein and then through the flow passages in the other of the minor sides before exiting the container via the fluid outlet structure. 
         [0010]    According to another aspect there is provided a multi-cell to electrochemical battery comprising: a casing having an interior divided into a plurality of battery cell compartments by at least one partition; a fluid circuit comprising a plurality of flow passages extending across said container through said at least one partition; fluid inlet structure to receive input fluid and deliver said input fluid to said fluid circuit; fluid outlet structure to permit the egress of fluid exiting said fluid circuit from said container; and a plurality of electrochemical battery cells accommodated in each battery cell compartment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    Embodiments will now be described more fully with reference to the accompanying drawings in which: 
           [0012]      FIG. 1  is a perspective view taken from above and from the side of a multi-cell electrochemical battery; 
           [0013]      FIG. 2  is a front view of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0014]      FIG. 3  is a side view of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0015]      FIG. 4  is a top plan view of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0016]      FIG. 5  is a perspective view taken from above and from the side of a main casing forming part of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0017]      FIG. 6  is a front cross-sectional view of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0018]      FIG. 7  is a perspective view of an electrochemical cell forming part of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0019]      FIGS. 8   a  and  8   b  are perspective views of side panels forming part of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0020]      FIGS. 9   a  and  9   b  are perspective cross-sectional views of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0021]      FIG. 10  is a perspective view of the multi-cell electrochemical battery of  FIG. 1  with its cover panel made transparent to expose the top panel of the multi-cell electrochemical battery; 
           [0022]      FIG. 11  is an exploded perspective view of a portion of the multi-cell electrochemical battery of  FIG. 1 ; 
           [0023]      FIG. 12  is a perspective view of the multi-cell electrochemical battery of  FIG. 1  with the cover panel made transparent to expose a battery management system (BMS) disposed on the top panel; and 
           [0024]      FIG. 13  is a perspective cross-sectional view of the multi-cell electrochemical battery of  FIG. 1  showing fluid flow therethrough. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0025]    Turning now to  FIGS. 1 to 4 , a multi-cell electrochemical battery is shown and is generally identified by reference numeral  20 . Multi-cell electrochemical battery  20  is suitable for use in a variety of commercial and industrial applications including but not limited to energy storage applications and vehicular applications (e.g. motorized wheelchairs, scooters, motorcycles, snowmobiles, personal watercraft, all terrain vehicles (ATVs), automobiles, trucks, busses, construction equipment) etc. Multi-cell electrochemical battery  20  comprises a rectangular main casing  22  comprising side panels  24   a  and  24   b  secured to opposite major sides of a generally rectangular container  40  (see  FIG. 5 ), a top panel  26  secured to and overlying the container  40  and a cover panel  28  secured to and overlying the top panel  26 . The container  40 , side panels  24   a ,  24   b , top panel  26  and cover panel  28  are formed of non-conductive, molded lightweight, biodegradable plastic material and are secured together using adhesive, melting, ultrasonic welding or other suitable technique. Negative and positive conductive terminals  30   a  and  30   b , respectively, extend upwardly from the cover panel  28  at laterally spaced locations. A fluid inlet  32  is provided in side panel  24   a  adjacent its bottom left corner and a fluid outlet  24  is provided in side panel  24   b  adjacent its top right corner. The fluid inlet  32  and fluid outlet  34  communicate with a fluid circuit within the multi-cell electrochemical battery  20  to enable the temperature of the multi-cell electrochemical battery  20  to be controlled as will be described. 
         [0026]      FIG. 5  better illustrates the container  40 . As can be seen, the container  40  is of a unitary construction and has opposite major sides  42   a  and  42   b , opposite minor sides  44   a  and  44   b  and a bottom  46 . Side panel  24   a  is secured to major side  42   a  and side panel  24   b  is secured to major side  42   b . The interior of the container  40  is divided into a plurality of cell compartments  50 , in this example six (6) cell compartments, by partitions or webs  52 . In this embodiment, each cell compartment  50  is sized to receive a group of electrochemical cells  54  comprising three (3) electrochemical cells as shown in  FIG. 6 . A plurality of vertically spaced, generally parallel fluid passages  60  extends across the container  40  through each of the webs  52  as well as through each of the minor sides  44   a  and  44   b . The fluid passages  60  are generally equally spaced and have a diameter equal to approximately five (5) millimeters. 
         [0027]    A flange  62  extends about the perimeter of each major side  42   a ,  42   b  and is slightly inwardly spaced from the outer peripheral edges of the major side. A plurality of laterally spaced, vertical ribs  64 , in this example three (3) ribs, is formed on each major side  42   a ,  42   b . The ribs  64  formed on major side  42   a  are offset from the ribs formed on major side  42   b.    
         [0028]      FIG. 7  better illustrates one of the electrochemical cells  54 . As can be seen, in this embodiment, each electrochemical cell  54  is a lithium ion battery cell such as that manufactured by Kokam Co. Ltd. of South Korea. The electrochemical cell  54  has a generally rectangular body Ma and positive and negative terminal tabs  54   b  and  54   c , respectively, extending upwardly from the top of the body  54   a.    
         [0029]      FIGS. 8   a  and  8   b  better illustrate the side panels  24   a  and  24   b . As can be seen, each side panel  24   a ,  24   b  has a major outer wall  70 , top and bottom walls  72  and  74  and opposite side walls  76  and  78 . Vertical ribs  80  extend between the top and bottom walls  72  and  74  at laterally spaced locations intermediate the side walls  76  and  78 . For each side panel  24   a ,  24   b , the peripheral edges of the top, bottom and opposite side walls are notched to take a configuration that is complimentary to the peripheral flange  62  extending about its associated major side  24 . The vertical ribs  80  are also in alignment with the vertical ribs  64 . In this manner, with the side panels  24   a ,  24   b  secured to the main casing  22 , the abutting ribs  80  and  64  divide the space between each side of the container  40  and its associated side panel into a plurality of isolated fluid chambers  90  as best shown in  FIGS. 9   a  and  9   b.    
         [0030]    For each cell compartment  50 , the electrochemical cells  54  are placed in the cell compartment in the same orientation. In this manner, the positive terminal to tabs  54   b  of the electrochemical cells  54  and the negative terminal tabs  54   c  of the electrochemical cells  54  in each cell compartment  50  are positioned adjacent opposite ends of the cell compartment. The orientation of the electrochemical cells  54  in successive cell compartments  50  is also reversed so that the polarities of the tabs adjacent the ends of the cell compartments  50  alternate along the multi-cell electrochemical battery  20  as shown in  FIG. 10 . 
         [0031]    The terminal tabs of the electrochemical cells  54  adjacent the ends of the cell compartments  50  pass through openings  100  in the top panel  26  as best shown in  FIG. 11 . Connectors  102  interconnect the adjacent terminal tabs of the electrochemical cells  54  in each cell compartment  50  thereby to connect the three electrochemical cells  54  in each cell compartment  50  electrically in parallel. The connectors  102  can be mechanically fastened to the terminal tabs or welded to the terminal tabs. Connectors  104  are also provided on the top panel  26  and extend between adjacent connectors  102  thereby to connect the groups of electrochemical cells  54  in the cell compartments  50  electrically in series. Similarly, connectors  104  can be mechanically fastened to the connectors  102  or welded to the connectors. 
         [0032]    A battery management system (BMS)  110  overlies the top panel  26  and is electrically connected to the connectors  104  as shown in  FIG. 12 . Battery management system  110  may be of any known type such as for example those sold by Analog Devices Inc. of Norwood, Mass. or Elithion of Boulder, Colo. As is known to those of skill in the art, the battery management system  110  monitors the temperature and voltage of each group of electrochemical cells  54 , monitors the current output of the multi-cell electrochemical battery  20 , defects abnormal battery operating conditions, protects against over/under voltage, current and/or temperature conditions etc. 
         [0033]    As mentioned above, controlling the temperature of the electrochemical cells  54  so that the temperature of the electrochemical cells remains within the specified operating temperature range is desired to prolong the operating life of the electrochemical cells. In particular, when it is desired to cool the multi-cell electrochemical battery  20 , cooled fluid (e.g. cooled gas or liquid) from a heat exchanger or other suitable source (e.g. the air conditioning unit of an automobile) is delivered to the fluid inlet  32 . The cooled fluid received by the fluid inlet  32  enters the multi-cell electrochemical battery  20 , fills the fluid chamber  90  adjacent the fluid inlet  32  and flows through the fluid passages  60  in the minor side  44   a . Fluid exiting the fluid passages  60  in the minor side  44   a  fills the fluid chamber  90  on the opposite side of the multi-cell electrochemical battery  20  and flows back through the flow passages  60  in the web  52  adjacent the minor side  44   a . Fluid exiting the flow passages  60  of the web  52  adjacent the minor side  44   a  fills the associated fluid chamber  90  and flows through the fluid passages  60  in the next web  52 . This back and forth fluid flow across the main casing  22  continues until the fluid exits the flow passages  60  in the minor side  44   b , fills the associated fluid chamber  90  and exits the multi-cell electrochemical battery  20  via the fluid outlet  34 . Cooled fluid therefore circulates back and forth across the multi-cell electrochemical battery  20  as shown by arrow  120  in  FIG. 13  thereby cooling the minor sides  44   a ,  44   b  and the webs  52 , which are in contact with the major surfaces of the outer electrochemical cells  54  in the cell compartments  50 . As a result, suitable cooling is provided to the electrochemical cells  54  to ensure the temperature of the electrochemical cells  54  remains within the specified operating range. Should the electrochemical cells  54  require heating to bring the electrochemical cells  54  up to operating temperature in cold climates, heated fluid rather than cooled fluid can be delivered to the fluid inlet  32 . 
         [0034]    As will be appreciated, the casing for the multi-cell electrochemical battery  20  is modular making it easy to manufacture and easy to assembly. Although the cell compartments  50  are shown as accommodating three electrochemical cells  54 , the cell compartments can be configured to hold fewer or more than three electrochemical cells. When the cell compartments  50  are configured to hold more than three electrochemical cells, care should be taken to ensure that adequate heat exchange between the outer and inner electrochemical cells in the cell compartments occurs so that the desired electrochemical cell cooling or heating results. Depending on the application, the multi-cell electrochemical battery  20  may include fewer or more cell compartments  50  than described above and illustrated. 
         [0035]    The positions of the fluid inlet  32  and the fluid outlet  34  on the side panels  24   a  and  24   b  are exemplary. Other suitable fluid inlet and fluid outlet positions can be utilized. If desired, multiple fluid inlets and multiple fluid inlets may also be utilized. Alternatively, the side panels  24   a  and  24   b  may be configured as manifolds. For example, side panel  24   a  may comprise a single fluid inlet and have internal flow passages formed in the outer major wall  70  that deliver input fluid to the fluid chambers  90  in parallel. Side panel  24   b  in this case similarly has internal flow passages formed in the outer major wall that receive fluid from the fluid chambers  90  that has exited the flow passages  60  and that deliver the received fluid to a single fluid outlet. 
         [0036]    Rather than using connectors  102  and  104  that are mechanically fastened or welded to the terminal tabs and to each other, conductive adhesive can be used to connect the electrochemical cells in each cell compartment electrically in parallel and to connect the groups of electrochemical cells in the cell compartments electrically in series. 
         [0037]    Although embodiments have been described with reference to the drawings, those of skill in the art will appreciate that variations and modifications may be made without departing from the spirit and scope thereof as defined by the appended claims.