CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation application of international application No. PCT/EP2015/078507 having an international filing date of 3 Dec. 2015 and designating the United States, the international application claiming a priority date of 4 Dec. 2014, based on prior filed German patent application No. 10 2014 018 231.2, the entire contents of the aforesaid international application and the aforesaid German patent application being incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a rechargeable battery assembly for a vehicle, wherein the rechargeable battery assembly comprises a metal-air rechargeable battery. 
         [0003]    Due to their achievable high-energy density, metal-air rechargeable batteries are suitable in particular for mobile applications, for example, for vehicles. An example of metal-air rechargeable batteries are lithium-air rechargeable batteries. Their function will be explained briefly in the following. When the lithium-air rechargeable battery is discharged, an electron is released at a lithium anode and a positive lithium ion passes through an electrolyte to the carbon cathode. At the carbon cathode, the lithium ion reacts with oxygen in a reduction process first to lithium oxide and then to lithium peroxide. In order for this reduction process to take place, the carbon cathode is coated with a catalyst, is highly porous, and comprises therefore a very large surface area. When charging the lithium-air rechargeable battery, this process is reversed. Oxygen is released at the carbon cathode; metallic lithium is deposited at the lithium anode. 
         [0004]    The lithium anode is moisture sensitive because the metallic lithium can react violently with water. Due to its high porosity, the carbon cathode, on the one hand, is susceptible to contamination with particles such as dust or sand and, on the other hand, harmful gases contained in the air can act as catalyst poisons that can irreversibly damage the carbon cathode. Up to now, lithium-air rechargeable batteries and also other metal-air rechargeable batteries have been tested only under laboratory conditions and loaded with high-purity gases in this context. 
       SUMMARY OF THE INVENTION 
       [0005]    It is therefore object of the present invention to provide an improved rechargeable battery assembly. 
         [0006]    Accordingly, a rechargeable battery assembly for a vehicle is proposed comprising a metal-air rechargeable battery; a filter device configured to condition the inlet air supplied to the metal-air rechargeable battery in such a way that the inlet air exhibits predetermined inlet air values, in particular a predetermined (relative) air humidity; and a control system. The control system is coupled to several sensor devices for receiving sensor signals for inlet air parameters and is configured to adjust, depending on the sensor signals, valve devices for inlet air flows for controlling the predetermined inlet air values, in particular the (relative) air humidity. 
         [0007]    The metal-air rechargeable battery comprises preferably an anode or first electrode which is manufactured of a metal block and a cathode or second electrode which is manufactured of a mesoporous carbon. Depending on which metal is employed as material for the first electrode, the control system is configured to adjust the relative air humidity contained in the inlet air to a value which is required for the metal. When the first electrode is manufactured of lithium, for example, it is required to remove from the inlet air the entire or at least approximately the entire air humidity because of the high reactivity of lithium with water. When using silicon as electrode material, it is required, on the other hand, that the air humidity contained in the inlet air is controlled by means of the control system to a defined and constant value. In this way, damage to the metallic electrode material is prevented for the service life of the metal-air rechargeable battery. Supplying the metal-air rechargeable battery with high-purity gases under laboratory conditions is not needed. The control system can be a control unit. Preferably, the control system is coupled to a vehicle control unit of the vehicle. Inlet air values are to be understood, for example, as the relative air humidity of the inlet air, loading of the inlet air with harmful gases, and/or loading of the inlet air with particles. 
         [0008]    The rechargeable battery assembly is in particular suitable for vehicles such as motor vehicles, trucks, motorcycles, aircraft, construction vehicles, rail vehicles, and watercraft. Moreover, the rechargeable battery assembly can also be used for immobile applications as in building technology or the like. 
         [0009]    In embodiments, the filter device comprises a pre-separator and/or a particle filter for separating particles from the inlet air. The pre-separator can be a cyclone separator, for example. For particle filtration, the particle filter can comprise a filter medium which is manufactured of paper and/or plastic material. Furthermore, the filter medium can be coated, impregnated, and/or provided with a nanofiber layer. 
         [0010]    In further embodiments, downstream of the pre-separator and/or of the particle filter, a first sensor device for detecting inlet air parameters such as loading of the inlet air with harmful gases and/or humidity is provided. The first sensor device is preferably connected by means of a signal line to the control system. 
         [0011]    In further embodiments, the filter device comprises a filter element that is configured to remove harmful gases from the inlet air, wherein the filter element is arranged downstream of the first sensor device. In particular, the filter element is configured to chemically filter harmful gases such as sulfur oxides SO x , ammonia NH 3 , nitrogen oxides NO x , hydrogen sulfide H 2 S, carbon monoxide CO, carbon dioxide CO 2  from the inlet air L. The filter element may comprise, for example, activated carbon for chemical filtration. Moreover, the filter element may comprise potassium carbonate K 2 CO 3  and/or calcium hydroxide Ca(OH) 2  that reacts chemically with acidic harmful gases such as sulfur oxides SO x  or hydrogen sulfide H 2 S in order to neutralize these harmful gases. The filter element configured to remove harmful gases from the inlet air can be arranged downstream or upstream of a filter element that is configured to remove humidity from the inlet air. 
         [0012]    In further embodiments, downstream of the first sensor device, a first valve device is provided that is configured to guide the inlet air, depending on the inlet air parameters detected by the first sensor device, through or past the filter element that is configured to remove harmful gases from the inlet air. The first valve device is preferably a multi-way valve that is controllable by the control system. 
         [0013]    In further embodiments, downstream of the filter element configured to remove harmful gases from the inlet air, a second sensor device is provided for detecting inlet air parameters such as loading of the inlet air with harmful gases and/or humidity. The second sensor device is preferably connected by means of a signal line to the control system. 
         [0014]    In further embodiments, the filter device comprises a filter element that is configured to remove humidity from the inlet air, wherein the filter element is arranged downstream of the second sensor device. The filter element can comprise a drying agent, for example, silica beads. The silica beads can be sprinkled onto the filter medium of the filter element and can be glued thereto. Moreover, the filter medium can be designed in a layer structure, wherein, for example, a layer of silica beads can be arranged between two nonwoven layers. In addition or optionally, the filter medium may comprise an absorber material, in particular a so-called superabsorber, a functionalized membrane or the like. 
         [0015]    In further embodiments, downstream of the second sensor device, a second valve device is provided that is configured to guide the inlet air, depending on the inlet air parameters detected by the second sensor device, through or past the filter element that is configured to remove humidity from the inlet air. The second valve device is preferably a multi-way valve that is controllable by the control system. 
         [0016]    In further embodiments, downstream of the filter element that is configured to remove humidity from the inlet air, a third sensor device for detecting the humidity of the inlet air is provided. The third sensor device is preferably connected by means of a signal line to the control system. 
         [0017]    In further embodiments, downstream of the third sensor device, a third valve device is provided that is configured to supply, depending on the humidity of the inlet air detected by the third sensor device, the inlet air to the metal-air rechargeable battery or an air outlet for regenerating the filter element configured to remove humidity from the inlet air. The third valve device is preferably a multi-way valve that is controllable by the control system. The inlet air supplied to the air outlet can be heated by means of a heating device and, for regenerating the filter element, can be passed through the latter. 
         [0018]    Further possible implementations of the rechargeable battery assembly comprise also combinations, not explicitly mentioned, of features or configurations of the rechargeable battery assembly described above or in the following with regard to the embodiments. In this context, a person of skill in the art will also add or modify individual aspects as improvements or supplements to the respective basic form of the rechargeable battery assembly. 
         [0019]    Further embodiments of the rechargeable battery assembly are subject matter of the dependent claims as well as of the embodiments of the rechargeable battery assembly described in the following. In the following, the rechargeable battery assembly will be explained in more detail with the aid of embodiments with reference to the attached figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a schematic section illustration of an embodiment of a metal-air rechargeable battery in a charging state. 
           [0021]      FIG. 2  is a schematic section illustration of the metal-air rechargeable battery according to  FIG. 1  in a discharging state. 
           [0022]      FIG. 3  is a schematic section illustration of a further embodiment of a metal-air rechargeable battery in a discharging state. 
           [0023]      FIG. 4  is a schematic section illustration of a further embodiment of a metal-air rechargeable battery in a discharging state. 
           [0024]      FIG. 5  is a schematic view of an embodiment of a rechargeable battery assembly. 
       
    
    
       [0025]    In the Figures, same reference characters identify same or functionally the same elements as far as nothing to the contrary is indicated. 
       DETAILED DESCRIPTION 
       [0026]      FIG. 1  shows a schematic section view of a metal-air rechargeable battery  1  in a charging state.  FIG. 2  shows a schematic section illustration of the metal-air rechargeable battery  1  in a discharging state. The metal-air rechargeable battery  1  comprises an anode or first electrode  2  manufactured of metal, in particular of lithium Li, and a cathode or second electrode  3 . In the following, only lithium-air rechargeable batteries  1  are explicitly described. 
         [0027]    The second electrode  3  is constructed of mesoporous carbon C and is not directly participating in the electrochemical process. According to the definition of the International Union of Pure and Applied Chemistry (IUPAC), mesoporous solid bodies are porous materials with a pore diameter between 2 nm and 50 nm. Carbon C serves as an electrical conductor and connector; the mesoporous structure serves for maximizing the surface area in order to facilitate reaction of oxygen O 2  with lithium ions Li +  in the area of the second electrode  3 . 
         [0028]    The first electrode  2  is comprised of a block of metallic lithium Li. Alternatively, the first electrode  2  can be comprised of a different metal, for example, silicon. Between the two electrodes  2 ,  3 , there is an electrolyte  4  which can be liquid or solid depending on the embodiment of the lithium-air rechargeable battery  1 . In the case of a solid electrolyte, a solid state rechargeable battery is provided. Moreover, the electrolyte  4  can be an organic liquid that does not react with lithium Li. 
         [0029]      FIG. 3  shows a schematic section illustration of an embodiment of a lithium-air rechargeable battery  1  with a water-based electrolyte  4 . In order to prevent a reaction of the metallic lithium Li with the electrolyte  4 , between the first electrode  2  and the aqueous electrolyte  4  a protective layer  5  is provided. The protective layer  5  can be a glass-ceramic layer applied to the metallic lithium Li. For example, the protective layer  5  is a so-called LISICON layer (LiM 2 (PO 4 ) 3 ). The protective layer  5  enables that the lithium Li remains stable in the aqueous environment. 
         [0030]      FIG. 4  shows a schematic section view of an embodiment of a hybrid lithium-air rechargeable battery  1 . Here, between the first electrode  2  and the protective layer  5  an organic electrolyte  4  and between the protective layer  5  and the second electrode  3  an aqueous electrolyte  4  are arranged. 
         [0031]    The basic function principle in all types of lithium-air rechargeable batteries  1  is substantially identical. During discharge ( FIGS. 2, 3, 4 ), an electron e −  is released at the first electrode  2  and a positive lithium ion Li +  is transferred through the electrolyte  4  to the second electrode  3  where the lithium ion Li +  reacts with oxygen O 2  first to lithium oxide Li 2 O and subsequently to lithium peroxide Li 2 O 2 . The following reduction process takes place in this context: O 2 +4e − →2 O 2− . In order for this reduction process to be able to take place, the second electrode  3  is coated with a catalyst, is highly porous, and comprises therefore a very large surface area. Therefore, the second electrode  3 , on the one hand, is susceptible to contamination with particles such as, for example, dust or sand, that can clog or block the second electrode  3 ; on the other hand, harmful gases such as sulfur oxides SO x , ammonia NH 3 , nitrogen oxides NO x , hydrogen sulfide H 2 S, carbon monoxide CO, carbon dioxide CO 2  and others act as catalyst poisons that can irreversibly damage the second electrode  3 . Moreover, the second electrode  3  is also moisture sensitive. 
         [0032]    When charging ( FIG. 1 ) the lithium-air rechargeable battery  1 , this process is reversed. Oxygen O 2  is released at the second electrode  3 ; metallic lithium Li is deposited at the first electrode  2 . The first electrode  2  is moisture sensitive because the metallic lithium Li can react violently with water. 
         [0033]      FIG. 5  shows a schematic view of an embodiment of a rechargeable battery assembly  6  with a lithium-air rechargeable battery  1  as described above. The lithium-air rechargeable battery  1  comprises a rechargeable battery control device  7  that is coupled by electrical signal lines  8 ,  9  to a control system  10  of the rechargeable battery assembly  6 . In  FIG. 5 , electrical signal lines are illustrated by solid lines and air paths by dashed lines. Air paths can be, for example, pipes or channels. The air paths can be integrated in a housing of the rechargeable battery assembly  6 . 
         [0034]    The rechargeable battery assembly  6  is supplied with inlet air L. The rechargeable battery assembly  6  comprises a filter device  11  which is configured to condition the inlet air L that is supplied to the lithium-air rechargeable battery  1  in such a way that the inlet air L has a predetermined relative air humidity. The filter device  11  comprises a pre-separator  12 , for example, a cyclone separator, and a particle filter  13  which is arranged downstream of the pre-separator  12 . The particle filter  13  is suitable for particle filtration. This means that the particle filter  13  is configured to mechanically retain particles such as dust, pollen, sand or the like contained in the inlet air L. In this way, clogging or blocking of the mesoporous second electrode  3  is prevented. For particle filtration, the particle filter  13  can comprise a filter medium manufactured of paper and/or plastic material. Moreover, the filter medium can be coated, impregnated, and/or provided with a nanofiber layer. 
         [0035]    Downstream of the particle filter  13 , a filter element  14  is arranged that is configured to remove harmful gases from the inlet air L. In particular, the filter element  14  is configured to chemically filter harmful gases such as sulfur oxides SO x , ammonia NH 3 , nitrogen oxides NO x , hydrogen sulfide H 2 S, carbon monoxide CO, carbon dioxide CO 2  from the inlet air L. These harmful gases can act as catalyst poisons that can permanently damage the catalyst provided at the second electrode  3 . The filter element  14  can comprise, for example, activated carbon for chemical filtration. Moreover, the filter element  14  can comprise potassium carbonate K 2 CO 3  and/or calcium hydroxide Ca(OH) 2  that chemically reacts with acidic harmful gases such as, for example, sulfur oxides SO x  or hydrogen sulfide H 2 S in order to neutralize these harmful gases. In this way, the catalyst action is permanently maintained. 
         [0036]    Downstream of the filter element  14 , a further filter element  15  is provided that is configured to remove humidity from the inlet air L. The filter element  15  can comprise a drying agent such as, for example, silica beads. The silica beads can be sprinkled onto a filter medium of the filter element  15  and can be glued thereto. Moreover, the filter medium can be of a layer structure, wherein, for example, a layer of silica beads can be arranged between two nonwoven layers. In addition or optionally, the filter medium can comprise an absorber material, in particular a so-called superabsorber, a functionalized membrane or the like. 
         [0037]    Between the particle filter  13  and the filter element  14 , a sensor device  16  and a valve device  17  are arranged, wherein the valve device  17  is positioned downstream of the sensor device  16 . The sensor device  16  is configured to determine the air quality. This means that the sensor device  16  can be configured to determine loading of the inlet air L with harmful gases. Moreover, the sensor device  16  can be configured to determine the humidity of the inlet air L. Loading of the inlet air L with harmful gases and the humidity of the inlet air L are determined as inlet air parameters. The sensor device  16  is coupled by means of the signal line  18  to the control system  10 . The valve device  17  is operatively connected by means of a signal line  19  to the control system  10 . The valve device  17  is arranged in or on an air path  20  connecting the sensor device  16  and the filter element  14 . 
         [0038]    Between the filter elements  14  and  15 , a further valve device  21  and a further sensor device  22  are positioned. The valve device  21  is arranged downstream of the sensor device  22 . In particular, the valve device  21  is provided in or on an air path  23  connecting the sensor device  22  and the filter element  15 . The sensor device  22  serves also for determining the air quality. In particular, the sensor device  22  can be configured to determine the air humidity of the inlet air L and loading thereof with harmful gases. The sensor device  22  is connected by means of a signal line  24  to the control system  10 . The valve device  21  is connected by means of a signal line  25  to the control system  10 . 
         [0039]    A further sensor device  26  and a further valve device  27  are positioned between the filter element  15  and the lithium-air rechargeable battery  1 , wherein the valve device  27  is arranged downstream of the sensor device  26 . The sensor device  26  is operatively connected by a signal line  28  to the control system  10 . The valve device  27  that is provided on or in an air path  29  connecting the sensor device  26  and the lithium-air rechargeable battery  1  is connected by means of a signal line  30  to the control system  10 . Downstream of the lithium-air rechargeable battery  1 , a further valve device  31  is provided which is connected by means of a signal line  32  to the control system  10 . A vehicle control unit  33  of a vehicle communicates by signal lines  34 ,  35  with the control system  10 . 
         [0040]    In operation of the rechargeable battery assembly  6 , the inlet air L flows first through the pre-separator  12  and the particle filter  13 , whereby coarse and fine particles are removed from it. The sensor device  16  detects loading of the inlet air L, from which particles have been removed, with harmful gases and/or humidity. When the filtered inlet air L contains no harmful gases or only a quantity of harmful gases that is below a predetermined limit value, the inlet air L is guided by means of the valve device  17  and an air path  36  past the filter element  14  and past the sensor device  22  into the air path  23 . When the inlet air L contains harmful gases to be removed, the valve device  17  is switched such that the inlet air L is guided through the filter element  14  in order to remove the harmful gases from the inlet air L. 
         [0041]    Downstream of the filter element  14 , the air quality of the inlet air L can be determined again by means of the sensor device  22 . When loading with harmful gases is too high, the control system  10  recognizes that the filter element  14  must be regenerated. For this purpose, the valve device  21  is switched such that the inlet air L is guided into an air outlet  37 . When the control system  10  detects by means of the sensor device  22  that the relative air humidity of the inlet air L already corresponds to a desired value, the valve device  21  is switched such that the inlet air L is guided via an air path  38  past the filter element  15  and past the sensor device  26  into the air path  29 . In case of a lithium-air rechargeable battery  1 , preferably the entire humidity is removed from the inlet air L. When using other metals, for example, silicon, as the electrode  3 , it may also be required to adjust the relative air humidity of the inlet air L to a defined value. Via the air path  38 , the inlet air L is guided by the valve device  17  into the air path  29  when neither harmful gas filtration nor conditioning of the humidity of the inlet air L is required. When the humidity of the inlet air L is above a predetermined limit value, the valve device  21  is switched such that the inlet air L flows through the filter element  15  and the sensor device  26 . 
         [0042]    When the sensor device  26  determines too high a value of the humidity of the inlet air L even though the inlet air L has been passed through the filter element  15 , the control system recognizes that the filter element  15  must be regenerated. Then the valve device  27  is switched such that the inlet air L flows to an air outlet  39 . Here, the inlet air L can be heated and can be guided again through the filter element  15  in order to regenerate it. The filter element  15  with the humidity-conditioning properties, for example, silica gel, can be regenerated by heat. For this purpose, the filter element  15  is heated or the inlet air L that is flowing through the filter element  15  is heated. The valve device  31  can be switched such that the outlet air A of the lithium-air rechargeable battery  1  can flow into the environment.
A rechargeable battery assembly for a vehicle has a metal-air rechargeable battery and a filter device to condition inlet air supplied to the metal-air rechargeable battery such that the inlet air exhibits predetermined inlet air values. The filter device has one or more filter elements, one or more sensor devices that determine at least one inlet air parameter, and one or more valve devices. A control system is coupled to the sensor devices so as to receive sensor signals for the at least one inlet air parameter and is coupled to the valve devices. The control system adjusts, depending on the received sensor signals, the valve devices in order to control the predetermined inlet air value in that the inlet air is guided through the filter elements; is guided past the filter elements; or is guided to an air outlet for regenerating the filter elements.