PATENT ABSTRACT
A battery module includes pressure release features ( 37, 38 ) for releasing excess pressure in a battery container, a wrap blanket ( 150 ) disposed between a module ( 13 ) and potting material ( 152 ) disposed in a case to secure modules ( 13 ) while allowing repair, replacement, recycling and/or reuse of modules ( 13 ) and a connector ( 130 ).

PATENT DESCRIPTION
FIELD OF THE INVENTION 
       [0001]    The subject disclosure relates to battery packs having cells and more particularly, to a battery pack for vehicles having a cooling system or a heating system for cooling the cells within the battery pack. 
       BACKGROUND AND SUMMARY 
       [0002]    Motor vehicles, such as, for example, hybrid vehicles and electric vehicles use propulsion systems to provide motive power. In hybrid vehicles, the propulsion system most commonly refers to gasoline-electric hybrid vehicles, which use gasoline (petrol) to power internal-combustion engines (ICEs), and electric batteries to power electric motors. These hybrid vehicles recharge their batteries by capturing kinetic energy via regenerative braking. When cruising or idling, some of the output of the combustion engine is fed to a generator (merely the electric motor(s) running in generator mode), which produces electricity to charge the batteries. This contrasts with all-electric cars which use batteries charged by an external source such as the grid, or a range extending trailer. Nearly all hybrid vehicles still require gasoline as their sole fuel source though diesel and other fuels such as ethanol or plant based oils have also seen occasional use. 
         [0003]    Batteries and cells are important energy storage devices well known in the art. The batteries and cells typically comprise electrodes and an ion conducting electrolyte positioned therebetween. Battery packs that contain lithium ion batteries are increasingly popular with automotive applications and various commercial electronic devices because they are rechargeable and have no memory effect. Storing and operating the lithium ion battery at an optimal operating temperature is very important to allow the battery to maintain a charge for an extended period of time. 
         [0004]    Due to the characteristics of the lithium ion batteries, the battery pack operates within an ambient temperature range of −20° C. to 60° C. However, even when operating within this temperature range, the battery pack may begin to lose its capacity or ability to charge or discharge should the ambient temperature fall below 0° C. Depending on the ambient temperature, the life cycle capacity or charge/discharge capability of the battery may be greatly reduced as the temperature strays from 0° C. Nonetheless, it may be unavoidable that the lithium ion battery be used where the ambient temperature falls outside the ambient temperature range. 
         [0005]    Alluding to the above, in a battery or battery assembly with multiple cells, significant temperature variances can occur from one cell to the next, which is detrimental to performance of the battery pack. To promote long life of the entire battery pack, the cells must be below a desired threshold temperature. To promote pack performance, the differential temperature between the cells in the battery pack should be minimized. However, depending on the thermal path to ambient, different cells will reach different temperatures. Further, for the same reasons, different cells reach different temperatures during the charging process. Accordingly, if one cell is at an increased temperature with respect to the other cells, its charge or discharge efficiency will be different, and, therefore, it may charge or discharge faster than the other cells. This will lead to decline in the performance of the entire pack. 
         [0006]    The art is replete with various designs of the battery packs with cooling systems. The U.S. Pat. No. 5,071,652 to Jones et al. teaches a metal oxide-hydrogen battery including an outer pressure vessel of circular configuration that contains a plurality of circular cell modules disposed in side-by-side relations. Adjacent cell modules are separated by circular heat transfer members that transfer heat from the cell modules to the outer vessel. Each heat transfer member includes a generally flat body or fin which is disposed between adjacent cell modules. A peripheral flange is located in contact with the inner surface of the pressure vessel. The width of each cell module is greater than the length of the flange so that the flange of each heat transfer member is out of contact with the adjacent heat transfer member. The flanges are constructed and arranged to exert an outward radial force against the pressure vessel. Tie bars serve to clamp the cell modules and heat transfer members together in the form of a stack which is inserted into the pressure vessel. 
         [0007]    The metal oxide-hydrogen battery taught by the U.S. Pat. No. 5,071,652 to Jones et al. is designed for cylindrical type of batteries. The U.S. Pat. No. 5,071,652 to Jones et al. teaches the heat transfer members be in direct contact with the vessel. Thus the U.S. Pat. No. 5,071,652 to Jones et al. does not teach creating a clearance between the vessel and the heat transfer members, which can be used to introduce cooling or heating agent to cool or heat the cells. 
         [0008]    The U.S. Pat. No. 5,354,630 to Earl et al. teaches a common pressure vessel of a circular configuration type Ni—H 2  storage battery having an outer pressure vessel that contains a stack of compartments. Each of the compartments includes at least one battery cell, a heat transfer member, and a cell spacer for maintaining a relatively constant distance between adjacent compartments. The heat transfer members include a fin portion, which is in thermal contact with the battery cell, and a flange portion which extends longitudinally from the fin portion and is in tight thermal contact with the inner wall of the pressure vessel. The heat transfer member serves to transfer heat generated from a battery cell radially to the pressure vessel. 
         [0009]    Similar to the metal oxide-hydrogen battery taught by the U.S. Pat. No. 5,071,652 to Jones et al., the storage battery taught by the U.S. Pat. No. 5,354,630 to Earl et al. is designed for cylindrical types of batteries. This metal oxide-hydrogen battery taught by the U.S. Pat. No. 5,354,630 to Earl et al. has the heat transfer members being in direct contact with the vessel thereby failing to create a clearance between the vessel and the heat transfer members which can be used to introduce cooling or heating agent to cool or heat the cells. 
         [0010]    The U.S. Pat. No. 6,117,584 to Hoffman et al. teaches a thermal conductor for use with an electrochemical energy storage device. The thermal conductor is attached to one, or both, of the anode and cathode contacts of an electrochemical cell. A resilient portion of the conductor varies in height or position to maintain contact between the conductor and an adjacent wall structure of a containment vessel in response to relative movement between the conductor and the wall structure. The thermal conductor conducts current into and out of the electrochemical cell and conducts thermal energy between the electrochemical cell and thermally conductive and electrically resistive material disposed between the conductor and the wall structure. The thermal conductor taught by the U.S. Pat. No. 6,117,584 to Hoffman et al. is attached to one or both of the anode and cathode contacts of the cell and not between the cells. 
         [0011]    The U.S. Pat. No. 6,709,783 to Ogata et al. teaches a battery pack having a plurality of prismatic flat battery modules constituted by nickel metal hydride batteries, arranged parallel to each other. Each battery module consists of an integral case formed by mutually integrally connecting a plurality of prismatic battery cases having short side faces and long side faces, the short side faces constituting partitions between adjacent battery cases and being shared. A plurality of spacers are made of a sheet bent in opposite directions such that alternately protruding grooves or ridges respectively contact the opposite long side faces of the battery modules for providing cooling passages between the battery modules. The battery pack taught by the U.S. Pat. No. 6,709,783 to Ogata et al. is intended to define voids, i.e. the cooling passages between the cells thereby diminishing the packaging characteristics of the pack. 
         [0012]    The U.S. Pat. No. 6,821,671 to Hinton et al. teaches an apparatus for cooling battery cells. As shown in FIG. 1 of the U.S. Pat. No. 6,821,671 to Hinton et al., a cooling fin is connected to the battery cell having railings for holding the cooling fin as each cooling fin slides between the railings thereby fitting the cooling fin within the respective battery cell thereby forming the aforementioned apparatus. The engagement of the cooling fin with the battery cell is presented in such a manner that the cooling fins do not extend beyond the battery cells. Thus, the cooling agent only serves its intended purpose if introduced from the side of the apparatus. If, for example, the cooling agent is applied to the front of the apparatus, only first battery cell is exposed to the cooling agent thereby preventing effective cooling of other battery cells. 
         [0013]    Alluding to the above, FIG. 7 of the U.S. Pat. No. 6,821,671 to Hinton et al. shows the apparatus wherein straps are inserted through ears extending from the cooling fins to connect multiple battery cells to form the apparatus and fins together to keep the battery cells in compression. The straps, as shown in  FIG. 7  deform the battery cells thereby negatively affecting chemical reaction between electrolyte, cathodes and anodes of each battery cells and resulting in a reduced life span of the cells. 
         [0014]    The Japanese publication No. JP2001-229897 teaches a battery pack design and method of forming the same. The purpose of the method is to create the voids between the cells for cool air to go through the voids and between the cells to cool the cells. Similar to the aforementioned U.S. Pat. No. 6,709,783 to Ogata et al., the battery pack taught by the Japanese publication No. JP2001-229897 is intended to define the voids between the cells thereby diminishing the packaging characteristics of the pack. 
         [0015]    Packaging of lithium battery cells is one of the areas of continuous development and research. Generally, the lithium battery cells packaged in a metallic case are known, as shown, for example, in U.S. Pat. No. 6,406,815. These metallic cases have the advantage of protecting the cells from handling and vibration damage. They are also dimensionally consistent, allowing for combining of multiple cases into a single large pack as disclosed in U.S. Pat. No. 6,368,743. However, the metallic cases are expensive to manufacture and each different configuration requires new dies to produce the various components and new tools to assemble those components. Consequently, techniques and materials for enclosing lithium battery cells in envelopes creating lithium battery cell packs have been developed, one type of which is disclosed in U.S. Pat. No. 6,729,908. Unfortunately, these packages do not provide structural rigidity or protection from handling and vibration nearly as well as the metallic cases, nor can they be combined into consistently sized groups of cells because of the inherent variation in the thickness of a lithium battery cell pack. 
         [0016]    Therefore, there remains an opportunity to improve upon the packs of lithium batteries of the prior art to increase the ambient temperature range at which the lithium battery operates and to provide a new battery pack with improved packaging and safety characteristics. 
         [0017]    Also, there remains an opportunity to maintain the battery pack at the optimal operating temperature to ensure the longest possible life cycle, rated capacity, and nominal charge and discharge rates. 
         [0018]    There is also an opportunity provide a new frame design that will present structural rigidity or protection from handling and vibration nearly as well as the metallic cases, as the cells are combined into consistently sized groups of cells or modules because of the inherent variation in the thickness of a lithium battery module or cell pack. Also there remains another opportunity to provide a solution that allows escape of gases away from the passenger compartment of the vehicle as pressure inside the battery pack exceeds the normal pressure thereby preventing escape of gases in to the compartment to eliminate potential risk and any unwanted hazardous events to driver and/or passengers. A battery assembly of the present disclosure is adaptable to be utilized in various configurations including and not limited to horizontally or vertically stacked battery cell packaging configurations used in an automotive vehicle. A plurality of battery modules are housed in a container, such as, for example, a dish or support tray which may include a cover. The container may be supported by a floor pan assembly or other part of the vehicle. The container presents a base and a plurality of side walls extending therefrom. At least one pressure release device is disposed in the base or walls for allowing fluid such as gas, to escape beyond the dish. The pressure release device may be, for example, a rupture element or disk formed by scoring or otherwise weakening areas of the container or a valve device. In one embodiment, a plurality Of rupture elements are disposed in the walls of the container. The rupture elements may present scoring lines that rupture under high pressure. As an alternative to the rupture elements, the battery assembly may include a valve device that would enable low pressure venting as well as emergency high pressure venting. In one embodiment, the valve device is disposed in the base of the container and is configured to selectively open and close an opening formed in the base of the container. In one embodiment, the valve device includes a closure plate with a seal or O-ring, a spring retainer portions of which extend across the opening in the base of the dish, a rod with a compression plate that is spaced opposite from the closure plate, and a spring or biasing element disposed between the closure plate and the compression plate and secured by the spring retainer. In one embodiment, the spring retainer is in the form of a cross and includes a core portion and, illustratively, at least four radial portions with each presenting a high pressure break feature. The valve device and rupture elements provide an over pressure relief system and act as “bursting elements”. The areas wherein the devices are disposed are designed to break open during an event which would cause the pressure within the battery pack to exceed specified limits. 
         [0019]    In one embodiment of the disclosed battery module, a potting material, such as for example, polyurethane, polyurethane foams, silicones or epoxies, is injected into the battery module placed in a case to at least partially or fully encapsulate the battery module and the corresponding cells thereby eliminating air gaps between the module and the case. The potting material also serves to prevent the electrode stack from shifting inside the cell packaging material during exposure to shock and vibration. The potting material also prevents the cell packaging from relaxing over time and allowing the electrolyte to settle into the base of the cell package and thus reducing the cell&#39;s electrical capacity. The potting/encapsulating material also prevents movement of the battery module within the battery pack case. A wrap blanket is disposed between the module and the potting material thereby providing “green” solution to allow the user to remove the module from the dish and service the module or simply to recycle the pack in a highly efficient fashion. 
         [0020]    An advantage of the present disclosure is to provide a solution that allows escape of gases away from the passenger compartment of the vehicle by placing pressure release elements in the dish, wherein the pressure release elements activate as pressure inside the pack exceeds the normal or predetermined pressure thereby preventing escape of gases in to the passenger compartment to eliminate potential risk and any unwanted hazardous events to driver and/or passengers. 
         [0021]    Still another advantage of the present disclosure is to provide a battery module having excellent retention that surrounds and secures the cells. 
         [0022]    Still another advantage of the present disclosure is to provide a battery module having excellent retention that surrounds and secures the electrode stack within the cell envelope from shifting. 
         [0023]    Still another advantage of the present disclosure is to provide a battery module encapsulated by the potting material which greatly reduces the potential permeation of liquids into the battery pack, or leakage from inside the battery module to the outside of the battery pack thereby preventing reduced product life or premature failures of the battery module. 
         [0024]    Still another advantage of the present disclosure is to provide a low mass design of a battery pack which includes polyurethane foam as a potential retention device, which is very competitive to that of traditional methods of retention, such as, for example, silicone or epoxy adhesives. 
         [0025]    Still another advantage of the present disclosure is to provide a packaging method which utilizes a case that houses the module and an encapsulant which locks the module in position and will allow the pack to be mounted in any orientation. 
         [0026]    Still another advantage of the present disclosure is to provide a battery pack that reduces manufacturing costs due to simplified assembly methods. 
         [0027]    Still another advantage of the present disclosure is to provide a pack that is simple in design and has a reduced mass. 
         [0028]    The disclosed battery assembly provides several advantages over the battery packs of the prior art by increasing an ambient temperature range at which the battery pack can operate. Also, the disclosed battery assembly helps maintain the battery pack at an optimal operating temperature to extend the life cycle of the battery pack, and to increase battery pack safety. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Other advantages of the present disclosure will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0030]      FIG. 1  is a perspective view of a battery pack assembly showing a dish and a cover with fluid inlets and outlets in which a plurality of battery sub-packs and other components are housed; 
           [0031]      FIG. 2  is a perspective view of the battery assembly of  FIG. 1  supported by a floor pan assembly of a vehicle; 
           [0032]      FIG. 3  is a sectional view taken along the longitudinal axis of the battery pack assembly supported by the floor pan assembly of the vehicle showing a valve acting as one embodiment of a high pressure release elements located in the base of the dish inside a central bridge formed to include a plenum allowing fluid such as air to be circulated through the battery pack assembly; 
           [0033]      FIG. 4  is a partial perspective view of the battery assembly of  FIG. 1  with the cover removed showing the dish, battery sub-packs and other components; 
           [0034]      FIG. 5  is perspective view of the dish or support tray of  FIG. 1  showing a plurality of pressure release elements in side walls of the dish; 
           [0035]      FIG. 6  is a perspective section view of the battery pack assembly of  FIG. 1  with the cover removed showing a typical airflow path through the battery pack assembly and showing pressure release elements located on the base of the dish in the area inside the bridge; 
           [0036]      FIG. 7  is a sectional view of a valve assembly type of pressure release element with a spring retainer in the form of a spring retainer cross attached to the base of the dish across a hole formed through the base of the dish with the valve assembly being biased to normally close the hole formed through the base of the dish; 
           [0037]      FIG. 8A  is a plan view of a retaining spring cross of one embodiment of the disclosed battery assembly attached to the base of the dish across a hole formed in the base of the dish with high pressure break features located at the periphery of the hole so that upon breakage portions of the retaining spring cross spanning the hole and the remainder of the valve assembly can be ejected from the battery assembly leaving a large opening for discharging fluid from the dish; 
           [0038]      FIG. 8B  is a plan view of a retaining spring cross of one embodiment of the disclosed battery assembly integrally formed in the base of the dish having high pressure break features located so that upon breakage the retaining spring cross and the remainder of the valve assembly can be ejected from the battery assembly leaving a large opening for discharging fluid from the dish; 
           [0039]      FIG. 9  is a plan view of a burst element formed by scoring the base of the dish; 
           [0040]      FIGS. 10  A, B and C are various views of the air inlet and outlet formed in the dish for circulating air through the dish; 
           [0041]      FIG. 11  is a perspective view of a heatsink element having a corrugated thermal fin extending from one edge of a sheet and an L-shaped thermal; 
           [0042]      FIG. 12  is a close up perspective view of a portion of the heatsink element of  FIG. 11 ; 
           [0043]      FIG. 13  is a perspective view of a frame member utilized to secure components of the battery module together; 
           [0044]      FIG. 14  is a perspective view of the heatsink element of  FIGS. 11 and 12  held within two frame members of  FIG. 13  to form a heatsink assembly; 
           [0045]      FIG. 15  is a perspective view of a cells secured on opposite sides of the heatsink assembly of  FIG. 14  by two frame members of  FIG. 13  to form a cell assembly; 
           [0046]      FIG. 16  is a perspective view of a cover utilized to form a battery module; 
           [0047]      FIG. 17  is a perspective view of a battery module formed utilizing a plurality of cell assemblies of  FIG. 15  and two covers of  FIG. 16 ; 
           [0048]      FIG. 18  is an exploded view of an alternate heatsink assembly utilizing slight variants of the heatsink of  FIG. 11  and the frame member  FIG. 13 ; 
           [0049]      FIG. 19  is an exploded view of a cell assembly formed using the heatsink assembly of  FIG. 18  and modified frame members of  FIG. 18 ; 
           [0050]      FIG. 20  is an exploded view of an alternate battery module; 
           [0051]      FIG. 21  is an exploded view of a portion of a battery sub-pack; 
           [0052]      FIG. 22  is a perspective view of a portion of a battery sub-pack including a housing and two battery modules of  FIG. 17 ; 
           [0053]      FIG. 23  is a perspective view of a battery sub-pack of  FIG. 22  with a housing cover attached; 
           [0054]      FIG. 24  is a perspective view from a different perspective of the battery sub-pack of  FIG. 23 ; 
           [0055]      FIG. 25  is a sectional view of the sub-pack of  FIG. 23  showing potting material received in the housing and a wrap blanket disposed between the potting material and the battery modules; 
           [0056]      FIGS. 26 and 27  are perspective views with portions removed of the battery sub-pack of  FIG. 23  and a connector and cable; and 
           [0057]      FIG. 28  is a perspective view with portions removed of the battery sub-pack of  FIG. 23 . 
       
    
    
     DETAILED DESCRIPTION 
       [0058]    Referring to the Figures, wherein like numerals indicate like or corresponding parts, a battery assembly or battery pack of the present disclosure is adaptable to be utilized in various configurations including and not limited to a horizontally or vertically stacked battery cell packaging configuration used in an automotive vehicle applications. The battery assembly or pack or battery pack assembly is generally shown at  10  in  FIG. 1 . The battery assembly  10  includes a plurality of battery sub-packs, each generally shown at  12  in  FIG. 1 . 
         [0059]    As best shown with reference to  FIGS. 11-22 , each battery module  13  of each sub-pack  12  includes a plurality of cells  91 . Preferably, each cell  91  is a lithium ion cell without limiting the scope of the present disclosure. Those skilled in the battery art will appreciate that other cells can be utilized within the scope of the present disclosure. Each cell  91  includes a plurality of battery components (not shown) co-acting between one another with electrolyte therebetween as known to those skilled in the lithium battery art. 
         [0060]    According to one embodiment, the disclosed battery pack has a plurality of battery modules  13  each presenting a multitude of cells  91  each sandwiched by respective heatsinks  90  formed from thermally conductive materials such as, for example, flat stock aluminum alloy foils and the like, without limiting the scope of the present disclosure. Preferably, each cell  91  is a lithium ion cell having a first current collector and a first electrode adjacent the first current collector and a second current collector and a second electrode of charge opposite from the first electrode and adjacent the second current collector. A separator layer is positioned between the first and second electrodes with the first and second electrodes conducting electrolyte therebetween. The plurality of the first electrodes and the second electrodes are stacked and packaged into an electrical insulating envelope to form a cell  91 . The cell packaging includes side edges and terminal ends. Illustratively, one terminal end includes a first bend extending therefrom in a first direction. Another terminal end includes a second bend extending therefrom in a second direction opposite from the first direction. One example of such a construction is described more fully in U.S. Patent Publication No. 2008/0090137, (U.S. patent application Ser. No. 11/748, 690 filed May 15, 2007), now U.S. Pat. No. 7,531,270, the disclosure of which is incorporated herein by this reference to the full extent permissible by law. 
         [0061]    The heatsink includes terminal ends, and top and bottom thermal transfer edges. The top and bottom thermal transfer edges may include a plurality of fins integral with and extending from the heatsink. The fins may be cold formed and are designed to transfer heat either to or from the cells  91  depending on application. A pair of electrically insulating spacer devices or ears are mechanically attached on each side of the heatsink. A plurality of studs are molded in to and extend from the spacer on one side of the heatsink, while a spacer without the plurality of studs but with relief for a sensor occupies the opposite side to form a heatsink assembly. The cell terminals are folded over the studs in an electrical series or electrical parallel configuration. The cells  91  are disposed between the heatsink assembly. Several examples of heatsinks that may be utilized within the teaching of this disclosure are described more fully in the above referenced U.S. Patent Publication No. 2008/0090137, now U.S. Pat. No. 7,531,270. 
         [0062]    In one embodiment of the disclosed battery assembly  10 , a plurality of flexible circuits are positioned over the studs for sensing voltage at every series connection. Integral sensors are positioned on the flexible circuit to provide temperature sensing. A nut with integral spring washer is threaded over each stud to provide for electrical conductivity and mechanical retention. Two end or compression plates  104 ,  106  are attached to the heatsink assemblies aligned with one another with the cells  91  disposed therebetween. One example of such an assembly that may be utilized within the teaching of this disclosure is described more fully in the above referenced U.S. Patent Publication No. 2008/0090137, now U.S. Pat. No. 7,531,270. 
         [0063]    In one embodiment of the disclosed heatsink assemblies, illustratively at least four tie rods  110  extend peripherally through each of the heatsink assemblies and the compression plates  104 ,  106  thereby placing the entire battery module  13  into a compressive state to promote shorter path length for ion conduction inside the cell  91  and improved thermal transfer of heat either to or from the heatsink  90 . 
         [0064]    As best shown in  FIGS. 2-6  and  21 - 27 , the modules  13  may be enclosed in housings to form a plurality of battery sub-packs  12  which are housed in a container such as a dish or support tray, generally indicated at  14 . As best shown in  FIGS. 2 and 3 , the dish  14  is supported by a floor pan assembly  16  or other part of the vehicle (not shown). As best shown in  FIGS. 3-5 , the dish  14  presents a base  18  and a plurality of side walls  20 ,  22 ,  24 ,  26  extending therefrom. The side walls  20 ,  22 ,  24 ,  26  may be generally perpendicular to the base  18  and may be slightly inclined without limiting the scope of the present disclosure. A peripheral lip  28  extends from each wall  20 ,  22 ,  24 ,  26 . The walls  20  and  24  that extend parallel to a bridge, generally indicated at  30 , include a plurality of first locking elements  32 , such as scalloped cut out portions to receive a respective plurality of second locking elements  34 , such as tongs, extending from the sub-packs  12 , as shown in  FIGS. 3 ,  4  and  24 , thereby securing the modules  12  within the dish  14  in mechanical connection and preventing relative movement of the modules  12  inside the dish  14 . The type of the mechanical connection as illustrated herein is not intended to limit the scope of the present disclosure. The walls  20  and  24  may also extend parallel to the bridge  30 . 
         [0065]    As shown for example, in  FIG. 6 , a typical airflow for controlling the temperature of the disclosed battery assembly has air from an external source entering the interior of the housing formed from the dish  14  and cover  70  through the air inlet  74  in the direction of arrow  1 . This external source of air may in some embodiments be conditioned air from a vehicles air conditioning and heater system. In such a situation, the pressure relief devices  38  help to prevent gasses from the battery pack from entering into the passenger compartment of a vehicle via the vehicles air conditioning and heating system during a high pressure condition, such as resulting from an emergency situation in which a battery sub-pack  12  rupture, by providing an alternative path for exhausting the gasses. The air entering the interior of the battery pack  10  flows through a plenum formed in the bridge  30  then in the direction of arrow  2  through the ports  60  and tubular member  128  into the interior of each battery sub-pack  12 . In the interior of each sub-pack  12  the air flows in the direction of arrow  3  across the fins  94  of the heat transfer elements  90 . The air exits the interior of each battery sub-pack  12  in the direction of arrow  4  through the slot  126  formed in the housing cover  124 . The air then flows in the direction of arrow  5  across the exterior of the housing cover  124  of each sub-pack  12  so that it can be exhausted in the direction of arrow  6  through the outlet port  72 . 
         [0066]    A plurality of pressure release elements are disposed in the dish  14  for allowing fluid such as gas, to escape beyond the dish  14 . The pressure release elements may include rupture elements or disks  37  disposed in the walls  20  and  24  for allowing fluid such as gas, to escape beyond the dish  14 . The rupture elements  37  may present scoring lines formed in the wall of the dish in a circular pattern that rupture under high pressure to discharge a disk from the wall leaving an opening through which pressurized fluid may exit the dish. Alternatively, as shown in  FIG. 9 , the rupture element  37  may present scored lines in other shapes in the base  18  of the dish  14 , such as the illustrated X-shape, that burst open in high pressure situations creating and opening for discharging fluid. 
         [0067]    As an alternative to the rupture elements  37 , the pressure release elements of the disclosed battery assembly  10  may include a valve device  38  that acts as the pressure relief element, as shown in  FIGS. 3 ,  6 ,  7  and  8  that would enable low pressure venting as well as emergency high pressure venting. As shown in  FIG. 7 , rupture elements  37  and valve devices  38  may be used together within the scope of the disclosure. 
         [0068]    In one embodiment of the disclosed battery assembly  10 , the valve device  38  is disposed in the base  18  of the dish  14  to selectively open and close an opening  41  extending through the base  18  of the dish  14  and is biased to normally close the opening  41 . One embodiment of the valve device  38  includes and a closure plate  40 , illustratively in the form of a disk, with a seal or O-ring  42 , a spring retainer  43  extending across the opening  41  in the base  18  of the dish, a linkage member such as rod  44  with a compression plate  46  that is spaced opposite from the disk  40 , and a spring or biasing element  48  disposed between the plate  46  and the disk  40  and secured by the spring retainer  43 , as best shown in  FIG. 7 . As shown for example in  FIG. 8A , one embodiment of the spring retainer  43  may include a retainer spring cross mechanically engaged with the base  18  of the dish  14 . As shown for example, in  FIG. 8B , one embodiment of the spring retainer  43  may be a retainer spring cross integrally formed in the base  18  of the dish  14 . As shown, in  FIGS. 8A  and B, the retainer spring cross  43  includes a core portion  47  formed to include a hole to allow rod  44  to pass therethrough and at least four radial portions  49  with each presenting a high pressure break feature  45 . Radially inwardly from each break feature  45 , each radial portion  49  is formed to include an upwardly extending spring retainer lip  51 . As shown in  FIGS. 7 and 8 , the break features  45  are positioned adjacent the walls of the opening  41  in the base of the dish  14 . The cross  43  holds the valve in place under normal low pressure situations but will break at the high pressure break features  45  under high pressure. Under normal operating pressure, the spring or biasing element  48  is located inside the dish  14 . Illustratively, the spring  48 , rod  44  and compression plate  46  are sized and the spring retainer lip  51  is positioned, so that upon rupture of the high pressure break features  45  in a high pressure situation, the valve assembly is at least substantially discharged from the dish  14  leaving a substantially unobstructed opening  41  for discharge of fluids. 
         [0069]    As shown, for example, in  FIGS. 3 ,  5  and  6 , a bridge  30  extends between the walls  22  and  26  of the dish  14 . The bridge  30  includes a top portion  50  and side walls  52  and  54  extending generally perpendicular to the side walls  20  and  24 . The bridge  30  divides the dish  14  into two sections  57  and  58  to house a plurality of the modules  13  which may be enclosed in cases or housings to form a plurality of battery sub-packs  12 . The side walls  52  and  54  present a plurality of slots  56  to provide fluid passage between the sections  58  and  57  to escape from the dish  14 . The valve devices  38  or rupture elements  37  will be disposed in the base  18  and between the side walls  52  and  54  extending from the walls  22  and  26 . The top portion  50  presents a plurality of ports  60  spaced from one another and extending in two rows from the walls  22  to wall  26  of the dish  14 . 
         [0070]    The valve devices  38  provide an over pressure relief system and act as “bursting elements”. The areas wherein the devices  38  and rupture elements  37  are disposed are designed to break open during an event which would cause the pressure within the battery pack  10  to exceed specified limits. 
         [0071]    In one embodiment of the disclosed battery assembly  10 , the ports  60  would fluidly communicate with each of the modules  12  as illustrated in  FIG. 6 . First and second brackets  62  and  64  are integral with and extend from the walls  22  and  26  and aligned with the top portion  50 . The brackets  62  and  64  may present various designs as shown in  FIGS. 2 and 6  or may be identical without limiting the scope of the present disclosure. A cover  70  is designed to enclose the dish  14  with the modules  12  disposed therein, as shown in  FIGS. 1-3  The material of the dish  14  and the cover  70  is not intended to limit the scope of the present disclosure. In one embodiment of the disclosed battery assembly, both of the cover  70  and the dish  14  may be formed from metal and metal alloys, polymers, and combination thereof. 
         [0072]      FIG. 10A-C  provides several views the first bracket  62 . Each bracket  62  and  64  includes airflow check valve features  72  and  74  connected to a respective biasing element  76 . Biasing elements  76  actuate the valve features  72  and  74  to open or close based on pack pressure. When cooling air is required, pressure from a fan system opens the inlet valve  72 . When the pressure is no longer present, the spring tension closes the valve  72 . If the pack  10  experiences internal overpressure, the inlet valve  72  will be closed and the exhaust valve  74  will be opened. The inlet valve  72  additionally serves to keep fumes and gases from a thermal event from entering the passenger compartment. 
         [0073]      FIGS. 11-20  include various illustrations of portions of a module  13  and subcomponents thereof, generally shown at  13  in FIGS.  17  and  20 - 21 . A thermally conductive plate, sheet, or foil  92  terminates to a first edge fin portion  94  presenting a corrugated configuration in the embodiment shown in  FIGS. 11-17  and an open box configuration in the embodiment shown in  FIGS. 18-21 .  FIG. 12  shows the second edge fin portion  95  being planar in the form of a bend to provide a thermal interface plane for an external heating or cooling device including but not limited to heater blankets and/or cooling jacket. Those skilled in the art will appreciate that numerous other shapes of the fin portion  94  can be utilized to provide better surface area for cooling or heating media, such as liquids, solids, or gasses, and the like, introduced to the fin portion  94  of each thermally conductive plate, sheet, or foil to either cool or to heat the cells of the battery module  13  of the sub-pack  12  without limiting the scope of the present disclosure. 
         [0074]    Alluding to the above, as shown, for example, in  FIGS. 15 and 19 , a cell assembly  90  includes two sets of frames  96  and  98 . The first set of frames  96 , as shown, for example, in  FIGS. 14 and 18 , presents a set of mechanical connections to secure the conductive plate, sheet, or foil  92  therebetween. The second set of frames  98  is used to secure the cells  91  attached to the opposite sides of the conductive plate, sheet, or foil  92 . 
         [0075]    As best illustrated in  FIGS. 16 ,  17  and  20 , a pair of compression plates, generally indicated at  104  and  106 , are designed to form terminal walls of each battery module  13  of each sub-pack  12 . A set of spaced holes  108  are defined in the compression plates  104  and  106  and also the cell assembly  90  to receive rods  110  extending through the compression plates  104  and  106  and the assembly  90  and are secured by fasteners  112  to apply pressure to the cells and to place the entire battery module  13  into a compressive state to promote a shorter path length for ionic conduction inside the cells  91  and improve heat transfer to the cell assemblies  90 . Alternatively, each compression plate  104  and  106  presents male and female features (not shown) that engage and retain adjacent assemblies  90 . A set of conical/countersink features may extend from the thermally conductive plate, sheet, or foil  92 . 
         [0076]    As best illustrated in  FIGS. 21 and 22 , two battery modules  13  are assembled into a sub-pack  12  and then placed into a sub-pack housing  122  and enclosed by a housing cover  124 . The housing cover  124  includes a slot  126  exposed to the thermally conductive plate, sheet, or foil  92  and a tubular member  128  with each of them fluidly connected to the ports  60 . The first locking elements  32  and the second locking elements  34 , such as tongs, extending from the housing  122 , as shown in  FIGS. 4 ,  5  and  24 . The housing  122  and the housing cover  124  are formed from a polymer material or non-polymer material or combination thereof without limiting the scope of the present disclosure. 
         [0077]    During assembly, a blanket of material  148  is wrapped around portions of each assembled battery module  13  to form a wrap blanket  150  to allow for easy removal of the module  13  from potting material  152  disposed between the module and the housing  122 . For example, a laminar flow of a mixed two-part encapsulating solution or potting material  152  is poured or otherwise introduced into the sub-pack housing  122  of the sub-pack  12 . The abundance of surface area contact and excellent adhesion properties of the encapsulating solution to the wrap blanket partially encompassing each module  13  provides a significant mechanical advantage of retention versus traditional methods such as RTV. The expansion of the encapsulating solution also greatly enhances the structural integrity of the battery pack  10  with respect to shock, vibration, and crush loads. The encapsulating solution illustratively depicted in  FIG. 25  at least partially encapsulates the battery module  13 , reducing air gaps between the module  13  and the case or housing  122 . 
         [0078]    Heat transfer coefficients are improved due to the elimination of associated insulation layers created by dead air gaps. The encapsulating solution shot size would be controlled not to allow it to rise over the heat sink fin  94  configuration for air cooled applications as shown in  FIG. 25 . The encapsulating solution  152  also serves to prevent the electrode stack from shifting inside the cell packaging material during exposure to shock and vibration. The encapsulating solution  152  also prevents the cell packaging from relaxing over time and allowing the electrolyte to settle into the base of the cell package and thus reducing the cell  91  electrical capacity. In one embodiment, the a wrap blanket  150  is formed from a polymeric material. Other materials that will inhibit the encapsulating material from adhering directly to the module  13  may be utilized within the scope of the disclosure. The wrap blanket  150  is disposed between the module  13  and the encapsulating solution  148  thereby providing “green” solution to allow the user to remove the module  13  from the sub-pack  12  and from the dish  14  and service the module  13  or simply to recycle the pack  10  or individual sub-packs  12  in a highly efficient fashion. 
         [0079]      FIGS. 26-28  present a Radsok assembly as generally shown at  130 . Each module  13  of each sub-pack  12  includes a sub-pack terminal  132  to be cooperable with a cable  134 . A Radsok connector  136  presents a core member to securely connect the Radsok connector  136  with the terminal  132 . An over molded boot  138  formed from a polymeric material encapsulates the connector  136  and extends to the cable  134 . A plurality of anti-pullout ribs  140  extend from the boot  138  to secure the cable  134  to the sub-pack terminal  132 . Upon insertions, the ribs  140  collapse as they are inserted into an opening  125  extending through the housing cover  124 . 
         [0080]    The disclosed battery sub-pack  12  is configured so that the housing cover  124  is formed to include an opening  125  extending between an interior and an exterior of the housing. The battery module  13  received in the interior of the housing includes at least one sub-pack terminal  132  having a connector portion  133  configured to act as a first portion of a connector. The connector portion  133  of the sub-pack terminal  132  is disposed adjacent the opening  125  in the housing cover  124 . The Radsok connector  136  forms a second portion of the connector and is physically and electrically coupled to the cable  134 . The Radsok connector  136  is configured to cooperate with the connector portion  133  of the sub-pack terminal  132  to electrically couple the sub-pack terminal  132  to the cable  134 . 
         [0081]    The boot  138  encapsulates at least a portion of the Radsok connector  136  and is formed at least in part from a resilient electrical insulating material. During insertion of the boot  138  into the opening  125 , the ribs  140  move to permit the Radsok connector  136  to extend through the opening  125  to be connected to the connector portion  133  of the sub-pack terminal  132 . Upon connection of the Radsok connector  136  to the connector portion  133 , the ribs  140  of the boot  138  assume a configuration such that the boot  138  and the housing cooperate to inhibit physical disconnection of the Radsok connector  136  from the connector portion  133 . 
         [0082]    The pack  10  includes a pre-charge circuit, a short circuit protection, a current sensor, a power connector, a pair of power contactors, and a pair of power buss bars extending from each module of each sub-pack  12  and connected to the respective power contactors. Alluding to the above, the battery pack  10  further includes temperature sensors (not shown) disposed within the housing for sensing the temperature of the cells. The temperature sensors are electrically connected to the flexible circuit that receives the temperature from the temperature sensors and routes the data to the battery controller circuits. If the temperature exceeds set safe limits, the battery controller will shut down the entire battery pack  10 . 
         [0083]    Those skilled in the art may appreciate that the battery pack  10  may include multiple temperature sensors and multiple control circuits. In addition, the arrangement of the cells, cooling devices, heaters, if required, the temperature sensors, and the control circuits may be different than as shown in the figures or described. Furthermore, one temperature sensor may be used with multiple control circuits, or each control circuit may have its own temperature sensor. Each may be controlled by the control circuit, or each heater, if required, may be controlled by separate control circuits. 
         [0084]    One skilled in the art can appreciate that a lithium ion battery may only operate optimally within an ideal temperature range. When the ambient temperature is below 0° C., the performance of the cells  91  is greatly reduced. Therefore, the heater heats the battery module  13  to the optimal operating temperature, which allows the battery module  13  to be used when the ambient temperature is below 0° C. For instance, with the heater, the battery module may be used in ambient temperatures as low as −40° C. Those skilled in the art will appreciate that the temperatures referenced are merely given as an example. Alternatively, the heater may be replaced by a water jacket devices (not shown) for cooling the co-planar interface surface for introducing cooling agent such as for example liquid, gas, or solids and the like to the heat sink assembly thereby cooling the cells. 
         [0085]    Alluding to the above other advantages of the present disclosure are shown. The battery pack  10  has very high energy density characteristics, wherein the high energy density is accomplished by assembling the cells, power and data bussing devices, the controllers, thermal management, and retention architecture in the small volume of space thereby improving packaging characteristics and providing a compact product. The battery pack  10  presents excellent retention methods that surrounds and secure the cells and present a cost effective design of the battery module  13  and sub-pack  12 . Another advantage of the present disclosure provides the battery module  13  is at least partially encapsulated by the potting material  152 , which greatly reduces the potential permeation of liquids into the battery module  13 , or leakage from inside the battery packs  10  to the outside of the battery pack  10  thereby preventing reduced product life or premature failures of the battery pack  10 . 
         [0086]    The disclosed battery pack provides other advantages over the prior art. The battery pack  10  has efficient packaging characteristics, which provide an excellent retention method that surrounds and secures the cells  91 , and the internal electrode stacks within the cells. Another advantage is the unique design of the battery pack  10  that provides improved adhesion and surface area contact between the blanket wrapped module and the housing of the battery sub-pack  12  and the encapsulant disposed therebetween and material density thereby providing the battery pack  10  with the structural integrity being superior to prior art battery packs using traditional retention methods. Still another advantage of the disclosed battery pack  10  is that the battery pack  10  has a chemical resistant design wherein the internal components of the battery pack  10  are encapsulated by the potting material  152  which greatly reduces the potential permeation of liquids into the battery pack  10 , or leakage from inside the battery pack  10  to the outside of the battery pack  10  thereby preventing reduced product life or premature failures of the battery pack  10 . 
         [0087]    While the invention has been described as an example embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.