Abstract:
A battery cell arrangement having a battery cell which is in the form of a film cell and includes a flat cell body with two end faces, a flexible cell rim surrounding the cell body, and two contact sections arranged on a rim side of the battery cell. The battery cell arrangement further has a frame arrangement which includes a first frame element and a second frame element which frames the cell body on all sides on the rim. At least one vent opening is provided on a side of the frame arrangement which faces away from the end faces of the cell body, in order to allow fluid, in particular gas, to emerge from the battery cell arrangement in the event of damage.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a National Stage Application of PCT International Application No. PCT/EP2010/066350 (filed on Oct. 28, 2010), under 35 USC. §371, which claims priority to U.S. Provisional Patent Application No. 61/255,640 (filed on Oct. 28. 2009), which are each hereby incorporated by reference in their respective entireties. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a battery cell arrangement having a battery cell which is in the form of a film cell. BACKGROUND OF THE INVENTION 
         [0003]    Film cells such as battery cells do not have a solid housing, but the components of the battery cell which are required to store electrical energy are surrounded by a robust film which forms a cell rim, like a fold, on the narrow faces of the cell body. Because there is no solid housing, the battery cell has a certain amount of flexibility, making it easier to use in a physical space which is often confined. Furthermore, film cells such as these—also referred to as pouch cells—are reliable and are comparatively cost-effective. However, the battery cell must be fixed by a device to make them robust. 
         [0004]    In many application fields, a plurality of battery cell arrangements of the type mentioned initially are combined to form an energy store, By way of example, energy stores such as these are used in hybrid or electrical vehicles. In order to save space, the battery cell arrangements are arranged packed as tightly as possible, for example by being stacked. The spatially tight arrangement of the battery cell arrangements places stringent requirements on the components which support the battery cells, in particular with respect to the battery cells being fixed in a compact manner, and at the same time reliably. It is also necessary to ensure that, for example in the event of damage to the battery cell, battery cell arrangements or other components which are arranged adjacent are not damaged, or are damaged as little as possible. 
       SUMMARY OF THE INVENTION 
       [0005]    One object of the present invention is therefore to provide a battery cell arrangement of the type mentioned initially, which is compact and allows reliable fixing of the battery cell. Another aim is for the battery cell arrangement to also comply with stringent safety requirements, and to be producible cost-effectively. 
         [0006]    In accordance with the invention, the battery cell has a flat cell body with two end faces, a flexible cell rim surrounding the cell body, and two contact sections arranged on a rim side of the battery cell. A frame arrangement which comprises a first frame element and a second frame element is furthermore provided, which frame arrangement frames the cell body on all sides on the rim. At least one vent opening is provided on a side of the frame arrangement which faces away from the end faces of the cell body, in order to allow fluid, in particular gas, to emerge from the battery cell arrangement in the event of damage. 
         [0007]    In other words, although the frame elements surround the cell body at the side while leaving its end faces free, a fluid which emerges, for example, from the cell body can in general, however, not emerge through the openings which are left free on the end faces of the frame elements since these are covered in a battery by battery cell arrangements which are arranged adjacent and are of the same or similar design, In conventional batteries having known battery cell arrangements, a leakage from the battery cell leads to fluid, generally an aggressive liquid and/or an aggressive gas, collecting in the battery cell arrangement. For example, because of its pressure and/or its chemical reaction capability, the fluid can cause considerable damage to the components of the battery cell arrangement. 
         [0008]    In order to prevent this, in addition to the large-area openings in the frame elements, which opening, leave the end faces of the cell body free, the frame arrangement has at least one additional opening—the vent opening which has already been mentioned above—through which the fluid can escape. An opening such as this can be provided in a simple manner, without this adversely affecting the robustness of the battery cell arrangement. 
         [0009]    The vent opening may be associated with a face of the battery cell which is opposite the rim face, which has the contact section, of the battery cell. This reliably protects the contact sections which allow electrical contact with the battery cell and which, in general, together with the electrical system connected to them, are comparatively sensitive to the said fluids. This also makes it largely possible to prevent the occurrence of short circuits caused directly or indirectly by the fluid. 
         [0010]    In order to ensure that liquids which occur in the internal area of the battery cell arrangement emerge as efficiently as possible, the vent opening can be arranged at the bottom when the battery cell arrangement is in the installed position. 
         [0011]    In accordance with one embodiment of the battery cell arrangement, the vent opening is formed by a recess on the first frame element and/or by a recess on the second frame element. In particular recesses of complementary design are arranged on the first frame element and on the second frame element, and together form the vent opening. 
         [0012]    The waste heat which occurs during charging and/or discharging processes of the battery cell can be dissipated efficiently if the frame arrangement at least partially forms at least one cooling channel, which extends along a side of the frame arrangement which is associated with the contact sections. The heat which occurs in this area during operation can be dissipated particularly efficiently. The contact sections which make it possible to tap off the stored electrical energy are furthermore cooled directly. The cooling channel need not be formed completely on the frame arrangement but, together with other components, can provide a cooling device which allows coolant, for example water, to be supplied. 
         [0013]    It is possible to provide that the cooling channel extends only along that side of the frame arrangement which is associated with the contact sections, in order to keep the battery cell arrangement design as simple as possible. In many cases, it is sufficient for the other sides of the frame arrangement to be free of cooling channels, provided that the contact sections which allow the electrical connection of the battery cell and the face of the cell rim which is associated with them are cooled. 
         [0014]    In particular, the cooling channel runs at the side adjacent to the contact sections of the battery cell and, in particular, runs on a plane which is arranged offset parallel to a plane which is defined by the contact sections. The contact sections are therefore also efficiently cooled. The said plane may, for example, be a separating plane between two battery cell arrangements which are arranged adjacent in a. battery, 
         [0015]    A physically simple configuration of a cooling system which is intended for cooling of the battery cell arrangement is obtained if an inlet opening and an outlet opening of the cooling channel are arranged on opposite sides of the frame arrangement. 
         [0016]    In order to minimize the flow resistance produced by the cooling channel, it may have a straight-line profile. 
         [0017]    In accordance with one embodiment, the first frame element of the frame arrangement forms half of a first cooling channel, and the second frame element of the frame arrangement forms half of a. second cooling channel, with one of the two frame elements together with the other of the two frame elements of a frame arrangement of identical design forming a complete first or second cooling channel. In particular, the respective cooling channel halves are formed by a recess in the form of a groove. This allows any desired number of frame arrangements to be stacked alongside one another or one on top of the other, with two adjacent frame arrangements together forming a respective cooling channel. 
         [0018]    A tubular component can be inserted into the respective cooling channel. In particular, the tubular component is a separate component. A complementary design of the cooling channel and of the component allows improved heat transfer, and therefore better dissipation of the waste heat created during operation of the battery cell. 
         [0019]    The cooling channel may be arranged on a holding section which extends from one of the frame elements in a direction which, in particular, is parallel to the planes which are formed by the end faces, in order to allow the cooling channel to pass by as close as possible to the contact sections in a suitable manner, while at the same time allowing the cooling channel to be easily physically connected to a corresponding coating system. 
         [0020]    In order to improve the cooling of the battery cell, in particular in the area of the end faces, a cold plate may be provided, which is thermally conductively connected to, and in particular is in direct contact with, the cooling channel and covers an area at least in places on one of the end faces of the cell body. 
         [0021]    In order to make it possible to compensate for thickness variations of the battery cell, which occur, for example, in the event of so-called “cell breathing” during charging and discharging of the battery cell, at least one of the end faces of the cell body is covered over an area, at least in places, with an elastomer layer. This further protects the end face against damage. 
         [0022]    In particular, at least one of the frame elements has a depression for holding the cold plate and/or the elastomer layer, with the depression being arranged in particular on a face of the frame element which faces away from the cell body, in order to make the battery cell arrangement as compact as possible. 
         [0023]    It is possible to provide that the frame arrangement comprises a clamping apparatus by means of which the cell rim can be clamped in with a friction fit between the frame elements, in order to fix the battery cell. 
         [0024]    In accordance with a further embodiment, the clamping apparatus has a slot, which is formed on one of the frame elements, and a projection, which has a complementary shape and is formed on the other frame element, in order to create a tongue-and-groove connection, by means of which the cell rim is at least partially clamped in. This improves the friction-fit fixing of the battery cell, as already mentioned above. The clamping apparatus may extend (with respect to a vertical installation position of the battery cell arrangement) along the entire height of the cell body on two mutually opposite sections of the frame arrangement, in order in this way to ensure that the battery cell is fixed over as large an area as possible. This ensures that the battery cell is fixed reliably even in the event of any distortion of the battery cell which may occur during operation. 
         [0025]    In order to reduce the production costs of the battery cell arrangement, the two frame elements may be physically identical. 
         [0026]    The invention furthermore relates to a battery arrangement having a plurality of battery cell arrangements which are arranged in the form of a stock, as claimed in at least one of the embodiments described above. In particular, each battery cell is associated with a first and a second frame element, with the first frame elements being physically identical and with the second frame elements being physically identical. Only two different types of identical parts are therefore required in order to provide the components which fix the battery cell. Particularly cost-effective production and assembly are achieved if (with the exception of those battery cells which are provided at the start and end of the stack) each battery cell is in principle associated with one and only one first and one second frame element. 
         [0027]    Further embodiments of the invention can be found in the description, the claims and the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention is described below by means of exemplary embodiments illustrated in the drawings in which show: 
           [0029]      FIG. 1  illustrates a battery cell in the form of a film cell. 
           [0030]      FIG. 2  illustrates one embodiment of a frame element. 
           [0031]      FIG. 3  illustrates an exploded illustration of one embodiment of the battery cell arrangement in accordance with the invention. 
           [0032]      FIG. 4  illustrates a cross section through the battery cell arrangement as illustrated in  FIG. 3 . 
           [0033]      FIG. 5  illustrates a perspective view of the battery cell arrangement as illustrated in  FIG. 3 . 
           [0034]      FIG. 6  illustrates one embodiment of the battery arrangement in accordance with the invention. 
           [0035]      FIG. 7  illustrates, schematically, a cross section through one embodiment of the battery arrangement in accordance with the invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0036]      FIG. 1  illustrates a battery cell  10  which is in the form of a film cell. Film cells such as these are also referred to as pouch cells. .instead of a solid housing, they have a sheath in the form of a film, and therefore have a certain amount of flexibility. 
         [0037]    The battery cell  10  comprises a flat, rectangular cell body  12  with end surfaces  12   a,    12   b  (end surface  12   b  cannot be seen in  FIG. 1 ), which surrounds the functional components that are required to store electrical energy. On the outer perimeter thereof, the cell body  12  is surrounded by a cell rim  14  in the form of a fold. Furthermore, on the upper face (with respect to the vertical installation position illustrated here), the battery cell  10  has contact sections  16  by means of which the battery cell  10  can be electrically charged and/or discharged. 
         [0038]    Since the battery cell  10  has comparatively little internal robustness, it must be provided with a supporting element, which is expediently of compact design.  FIG. 2  illustrates a frame element  18  which is intended for this purpose. The frame element  18  comprises a frame section  20  which surrounds the cell body  12  after assembly while at the same time leaving its end surfaces  12   a,    121  free. A holding section  22  is provided on the frame section  20  and extends away from the frame section  20  on the frame section plane. On its face which faces away from the frame section  20 , the holding section  22  has a cooling channel  25  in which a cooling tube  26  is arranged. As can be seen more clearly in  FIG. 7 , the cooling channel  25  surrounds only approximately half of the cooling tube  26 . 
         [0039]    On the left-hand and right-hand faces, and partially on its lower face, the frame section  20  has a clamping apparatus  28 , which is used to improve the friction-fit fixing of the cell rim  14 . The function of the clamping apparatus  28  will be explained in more detail in the following text. Furthermore, a recess  30  is provided on the lower face of the frame section  20 . In this area, the thickness of the frame section  20  of the frame element  18  is reduced in comparison to the other sections of the frame section  20 . In addition, the function of the recess  30  will be explained in more detail in the following text. 
         [0040]      FIG. 3  illustrates an exploded illustration of the major components of a battery cell arrangement  32 , The battery cell arrangement  32  comprises two preferably physically identical frame elements  18 ,  18 ′, between which the battery cell  10  is clamped in during its assembly. The cell rim  14  thereof is in this case held by the clamping apparatus  28  over virtually the entire height of the cell body  12 , on the right-hand and left-hand faces of the battery cell  10  in  FIG. 3 . No clamping apparatus is provided on the upper face of the respective frame element  18 ,  18 ′, associated with the contact sections  16 , in order not to damage the electrical contact between the contact sections  16  and the interior of the cell body  12 . On the lower face of the battery cell  10 , the cell rim  14  is likewise held by the clamping apparatus  28 , with the exception of the area of the recesses  30 . In other words, more than half of the circumference of the cell rim  14  is held by the clamping apparatus  28 , in order to ensure that the battery cell  10  is reliably fixed between the frame elements  18 ,  18 ′. 
         [0041]      FIG. 4  illustrates a cross section through the battery cell arrangement  32 . As can be seen, the clamping apparatus  28  surrounds a projection  34  on the upper frame element  18 , which projection  34  is associated with a slot  36  of complementary shape on the lower frame element  18 ′. A flank of the projection  34  or of the slot  36  facing the cell body  12  runs obliquely to the end surfaces  12   a,    12   b,  in order to avoid sharp edges, and the cell rim  14  is protected. 
         [0042]    In order to have to provide only one embodiment of the frame element  18 ,  18 ′ for production of a battery cell arrangement  32 , it is possible to provide for the clamping apparatus  28  to be in the form of a projection  34  on one face (for example the left-hand face) of the frame section  20 , and to be in the form of a slot  36  on the opposite face (for example the right-hand face), The frame elements  18 ,  18 ′ are then identical parts. 
         [0043]    Together, the projection  34  and the slot  36  form a tongue-and-groove connection, into which the cell rim  14  is clamped. Those surfaces of the frame elements  18 ,  18 ′ which are opposite the projection  34  and the slot  36  are planar, in order to allow a plurality of battery cell arrangements  32  of identical design to be stacked alongside one another or one on op of the other. 
         [0044]      FIG. 4  also illustrates that the frame elements  18 ,  18 ′ each have a recess  38  on the end face opposite to the projection  34  and the slot  36 , into which recess  38  elements like plates can be inserted in order to improve the cooling or to protect the end surfaces  12   a,    12   b.    
         [0045]      FIG. 5  illustrates a perspective view of an assembled battery cell arrangement  32 , The choice of the perspective makes it possible to see a vent opening  31 , which is formed by the two recesses  30  in the frame elements  18 ,  18 ′, on the lower face of the battery cell arrangement.  32  in the installation position. This makes it possible for gases and/or liquids to emerge from the battery cell arrangement  32 . This is particularly important when the battery cell arrangement  32  is part of a stack of a plurality of corresponding battery cell arrangements  32 , such that no fluid can emerge through the openings associated with the end surfaces  12   a,    12   b  of the cell body  12  in the frame elements  18 ,  18 ′, since this is covered by the adjacent battery cell arrangement  32 . 
         [0046]      FIG. 6  illustrates a battery arrangement  40 , which consists of a plurality of battery cell arrangements  32  of essentially identical design. The illustration shows that the cooling tubes  26  in the individual arrangements  32  can be connected in a simple manner to collecting lines for a coolant, which collecting lines run, for example, at right angles to the cooling tubes  26 . Since the cooling tubes  26  are designed to be free of bends, the flow resistance caused by them is low, thus making it possible to produce an efficient coolant flow. As can also be seen, the cooling tubes  26  cool, in particular, areas around the contact sections  16 , which require a particularly large amount of cooling. The illustrated configuration of the battery arrangement  40  and of the battery cell arrangements  32  which form them represents one possible way of on the one hand designing the cooling of the battery cells  10  to be as efficient as possible, while on the other hand avoiding complex designs, which are therefore costly and susceptible to faults. 
         [0047]      FIG. 7  illustrates a detail of a cross section through the battery arrangement  40  at right angles to the end surfaces  12   a,    12   b  of the cell bodies  12 . The design of the battery arrangement  40  will be explained by way of example with reference to the indicated battery cell arrangements  32 , 17 ′. 
         [0048]    The cell body  12  of the battery cell arrangement  32  makes contact on its left-hand end surface  12   a  with an elastomer layer  42 , which essentially completely covers it. Because of its elasticity, the elastomer layer  42  allows flexible thickness compensation for the cell body  12 . In other words, it absorbs changes in the distance between adjacent cell bodies  12  in order on the one hand to avoid play between them and on the other hand to allow the initially mentioned “cell breathing.” Complete suppression of the “cell breathing,” as occurs, for example, when using rigid spaces, adversely affects the performance of the battery cells  10 . 
         [0049]    The end surface  12   b  of the cell body  12  makes contact with a cold plate  44 , which extends to the cooling tube  26  associated with the battery cell arrangement  32 . The cooling tube  26  is arranged in a groove  46  in the cooling channel  25 . The cooling channel  25  is connected via the holding section  22  to the frame section  20  of the frame element  18  (cf.  FIG. 2 ). 
         [0050]    As already explained a number of times above, the cell rim  14  is clamped in between the respective frame sections  20  of the frame elements  18 ,  18 ′ of the battery cell arrangement  32 . The contact sections  16  also extend through this. The contact sections  16  run from the interior of the cell body  12  into an area which is cooled by the cooling tube  26 , and beyond it. They are therefore cooled particularly efficiently. Waste heat which occurs in the area of the end surface  12   b  in the battery cell  10  is dissipated via the cold plate  44  of the battery cell arrangement  32 , which cold plate  44  is likewise cooled by the cooling tube  26 . 
         [0051]      FIG. 7  furthermore illustrates that, because the adjacent battery cell arrangements  32 ,  32 ′ are designed to be essentially identical, this results, in an efficient manner, in a battery arrangement  40  which is tightly packed and nevertheless reliably cooled at the same time, with reliably fixed battery cells  10 . Each battery cell arrangement  32 ,  32 ′ is in each case associated with an elastomer layer  42  and a cold plate  44  as well as a cooling tube  26 . These components are, however, also used by the respectively adjacent battery cell arrangement  32 ′ or  32 , because of the regular arrangement, thus providing a cyclically repeating configuration of the functional components for an elastomer layer  42 , cell body  12 , cold plate  24 . 
         [0052]    The grooves  46  in the cooling channels  25  in the frame elements  18 ,  18 ′ reliably protect the cooling tubes  26 . For initial assembly, all that is necessary is to insert one cooling tube  26  for each battery cell arrangement  32 ,  32 ′ into the groove  46  in one of the frame elements  18 ,  18 ′. The free groove  46  in the adjacent battery cell arrangement  32 ′ or  32  completes the protection of the cooling tube  26  when the battery arrangement  40  is assembled, Although it is in principle possible to form the cooling tube  26  integrally with the frame element  18 ,  18 ′, it is, however, in many cases advantageous to manufacture the cooling tube  26  separately, for manufacturing reasons. 
         [0053]    Although embodiments have been described herein, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art 
       LIST OF REFERENCE SYMBOLS 
       [0054]      10  Battery cell 
         [0055]      12  Cell body 
         [0056]      12   a,    12   b  End surface 
         [0057]      14  Cell rim 
         [0058]      16  Contact section 
         [0059]      18  Frame element 
         [0060]      20  Frame section 
         [0061]      22  Holding section 
         [0062]      25  Cooling channel 
         [0063]      26  Cooling tube 
         [0064]      28  Clamping apparatus 
         [0065]      30  Recess 
         [0066]      31  Vent opening 
         [0067]      32 ,  32 ′ Battery cell arrangement 
         [0068]      34  Projection 
         [0069]      36  Slot 
         [0070]      38  Recess 
         [0071]      40  Battery arrangement 
         [0072]      42  Elastomer layer 
         [0073]      44  Cold plate 
         [0074]      46  Groove