WO2016180431A1

WO2016180431A1 - Vehicular metal/gas battery system with a gas cleaning apparatus

Info

Publication number: WO2016180431A1
Application number: PCT/EP2015/060140
Authority: WO
Inventors: Philipp OBERHUMER; Nikolaos Tsiouvaras; Simon NÜRNBERGER; Odysseas Paschos; Tokuhiko Handa; Peter Lamp; Hidetaka Nishikoori; Toshihiko Inoue
Original assignee: Bayerische Motoren Werke Aktiengesellschaft; Toyota Motor Corporation
Priority date: 2015-05-08
Filing date: 2015-05-08
Publication date: 2016-11-17
Also published as: DE112015006519T5

Abstract

The present invention is directed to a vehicular battery system, in particular for electric or hybrid automobiles. The battery system comprises a metal/oxygen battery pack configured to output electrical power, a gas reservoir configured to store oxygenous gas and being operatively coupled to the battery pack to supply oxygenous gas to said battery pack, and a gas cleaning apparatus configured to receive oxygenous gas, in particular ambient air, to clean said gas from contaminants and to supply the cleaned oxygenous gas to said battery pack. In addition, the battery system comprises a battery management system configured to control the supply of oxygenous gas from the cleaning apparatus and the gas reservoir to the battery pack. The battery system has at least two modes of operation, including a first mode that requires a first power output level lower than or equal to a second power level being electrochemically equivalent to the cleaning apparatus' maximum supply rate of oxygen in said first mode of operation, and at least one second mode that requires a third power output level greater than the second power level. The battery management system is configured to control the supply of oxygenous gas to the battery pack such that when the battery system is operated in the first mode, the battery pack is supplied with oxygenous gas output by the cleaning apparatus, and when the battery system is operated the second mode, the battery pack is additionally or instead supplied with oxygenous gas from the gas reservoir.

Description

VEHICULAR METAL/GAS BATTERY SYSTEM WITH A

GAS CLEANING APPARATUS

TECHNICAL FIELD

The present invention relates to the field of vehicular metal/oxygen battery systems, in particular for electric or hybrid automobiles. Specifically, the invention is directed to a vehicular battery system having a metal/ oxygen battery pack and a gas cleaning apparatus for cleaning oxygenous gas, in particular ambient air, to be consumed by the metal/ oxygen battery pack.

BACKGROUND

While traditionally most long-range vehicles, such as cars, trucks, buses, motorcy- cles, and non-electric railway locomotives, have been powered by gasoline or diesel engines, in recent years the development of electric or hybrid vehicles, in particular automobiles that are at least partially powered by electric motors has been steadily increasing. To that purpose various different battery systems have been developed as suitable storages for electric energy, including in particular lithium-ion batteries, which are used for most of today's electric and hybrid cars. One disadvantage of such lithium-ion batteries is their limited energy density, i.e. stored electrical energy per battery mass or per battery volume. This limitation is - amongst others - caused by the fact that all chemical components needed for the electrochemical reactions taking place in the battery cells are already contained in the charged battery, thus adding to its weight or volume.

To overcome this limitation another battery type has been conceived, which is commonly known as "metal/air battery" or "metal/oxygen battery". Such a battery comprises one or more electrochemical cells each having a first electrode - usually re- ferred to as "anode" - made of or at least containing a suitable metal, and a second electrode - usually referred to as "cathode" - working with ambient air or oxygen, and a separator arranged between the two electrodes to electrically separate them. In particular, the anode can comprise an alloy having such metal as a first component and one or more further metal or non-metal components, such as carbon (C), tin (Sn) or silicon (Si), wherein the metal component in such anode remains available to participate in the electricity generating chemical reactions of electrochemical, i.e. galvanic cell. Instead of such alloy also a transition metal oxide may be used as an anode material. Furthermore, an electrolyte, which may in particular be of the aqueous or solid type, is present in cathode and optionally in the separator. In particular, it is known to use zinc, aluminum or lithium as the metal for the anode. At the cathode side, oxygen is the relevant electrochemical component and unlike in lithium-ion batteries it does not have to be present in the charged battery from the beginning, but can rather be taken from ambient air or be delivered to the battery in the form of an oxygenous gas or pure oxygen from a source such as a tank or other reservoir during discharging of the battery. In this way, batteries having a much higher energy density than traditional lithium-ion batteries become possible. Furthermore, when such a battery is re-charged, oxygen is generated at the cathode and can be re-used in a subsequent discharging cycle.

US patent application publication US 2014/027261 1 A1 to Albertus et al. discloses a metal/oxygen battery for a motor vehicle, the battery having an oxygen supply system comprising a first oxygenated gas supply reservoir, a compressor with an outlet fluidly coupled to the first oxygenated gas supply reservoir, and a valve and pressure regulator fluidly coupled to the first oxygenated gas supply reservoir and to a positive electrode of the battery. The valve and pressure regulator is configured to place the first oxygenated gas supply reservoir in fluid communication with the positive electrode during a discharge cycle, and place the positive electrode in fluid communication with an inlet of the compressor during a charging cycle. Optionally, the battery also includes an air inlet that is coupled to the external atmosphere through a selectively permeable membrane. In one embodiment the battery is adapted to filter compressed air to remove contaminants that may negatively impact the operation of the battery's cells.

SUMMARY OF THE INVENTION Against this background, the present invention is directed to the problem of providing an improved metal/oxygen battery system for vehicles, in particular in view of a reduction of weight and/or size of the battery system.

A solution to this problem is provided by the teaching of the appended independent claims, namely by a vehicular battery system according to claim 1 and a method of operating such battery system according to claim 15. Various preferred embodiments and further improvements of the invention are provided in the dependent claims. The first aspect of the present invention is directed to a vehicular battery system. The battery system comprises a metal/oxygen battery pack configured to output electrical power, a gas reservoir configured to store oxygenous gas and being oper- atively coupled to the battery pack (2) to supply oxygenous gas to said battery pack, and a gas cleaning apparatus configured to receive oxygenous gas, in particular ambient air, to clean said gas from contaminants and to supply the cleaned oxygenous gas to said battery pack. In addition, the battery system comprises a battery management system configured to control the supply of oxygenous gas from the cleaning apparatus and the gas reservoir to the battery pack. The battery system has at least two modes of operation, including a first mode that requires a first power output level lower than or equal to a second power level being electrochemically equivalent to the cleaning apparatus' maximum supply rate of oxygen in said first mode of operation, and at least one second mode that requires a third power output level greater than the second power level. The battery management system is configured to control the supply of oxygenous gas to the battery pack such that when the battery system is operated in the first mode, the battery pack is supplied with oxygenous gas output by the cleaning apparatus, and when the battery system is operated in the second mode, the battery pack is additionally or instead supplied with oxygenous gas from the gas reservoir. The battery system according to the first aspect of the invention is based in particular on the concept that at least two different sources of oxygenous gas are provided, wherein none of these two sources alone is sufficiently dimensioned to provide enough oxygen to enable the full capacity of the battery system's battery pack, in particular in view of both peak power and energy storage capacity, while by intelli- gently combining these sources the full capacity of the battery system is enabled. A first one of the sources is a gas cleaning apparatus, which is configured to receive oxygenous gas, in particular ambient air, and clean it to remove contaminants, and to supply the cleaned gas to the battery pack of the battery system. A second one of the sources is a gas reservoir, which is filled with oxygenous gas, preferably com- pressed air within an oxygen concentration similar or greater than the typical oxygen concentration in atmospheric air. In particular, the gas reservoir may be filled with substantially pure oxygen. Thus, both the cleaning apparatus and the gas reservoir can be formed with reduced total size and weight relative to a cleaning apparatus respectively gas reservoir being dimensioned to alone support the full capacity of the battery pack. This in turn may reduce the weight of the battery system and con- sequently also of the vehicle comprising the battery system and thus extends the vehicle's electric driving range. Furthermore, the gas reservoir can be used advantageously to provide oxygen to the battery pack when the cleaning apparatus is not operable, e.g. during startup when the battery pack doesn't provide enough energy yet to drive to cleaning apparatus, and in a third mode of operation to store oxygen that is generated in the battery pack during a charging cycle.

The term "oxygenous gas", as used herein, relates to a gas that contains oxygen as one of its components. In particular, the oxygen component may comprise molecular oxygen, preferably 0₂. Also pure or substantially pure oxygen is an "oxygenous gas" as used herein. The oxygenous gas is selected in dependence from the chemical materials of the electrodes of the battery pack, in particular of its anode side, such that the necessary chemical reactions for the generation of electrical energy consume the oxygen in the oxygenous gas during a discharging cycle. The term "metal/oxygen battery", as used herein, relates to a battery as described in detail above, where the electrochemically relevant chemical component of one of the electrodes is oxygen, in particular O2. To support the electrochemical reactions taking place in the battery, oxygenous gas is provided to the one or more metal/oxygen galvanic cells of the battery, specifically to the cell's cathode side. In par- ticular, a "metal/air battery", i.e. a battery that uses air as such oxygenous gas is also an embodiment of a "metal/oxygen battery", as used herein.

The term "energy storage capacity", as used herein, relates to the electric energy capacity of a battery respectively battery pack, i.e. the amount of electrical energy (usually expressed in kWh) it can store when fully charged. Frequently, a nominal energy storage capacity of a battery is provided by the manufacturer on an outer surface of the battery system and/or in related documentation. At least when the battery pack is new and has not suffered any degradation yet, the nominal energy storage capacity usually coincides, at least substantially, with the factual energy storage capacity of the battery pack. The term "gas cleaning apparatus", as used herein, relates to a device that is capable of receiving a gas to be cleaned, in particular ambient air, to filter that gas to remove at least selected contaminants, and to supply the cleaned gas, in particular at an outlet of the cleaning apparatus. In particular, the cleaning apparatus can be an active device that consumes energy to process the to-be-cleaned gas, such as for cooling it to remove moisture or for pumping it through a filter material to remove particles or C0₂. Alternatively the cleaning apparatus may be a passive device, such as a mere sheet of filter material or a membrane selectively allowing certain components of the gas, in particular O2, to pass through it, while other components are blocked.

The term "battery management system", as used herein, relates to an entity of the battery system that is adapted to control the supply of oxygenous gas from the cleaning apparatus in the gas reservoir to the battery pack. In particular, the battery management system may comprise one or more CPUs running respective control/regulation software and means to communicate control signals to other entities of the battery system such as the gas reservoir, the cleaning apparatus, or optional entities such as a pressure regulator, one or more valves or a compressor. The term "control", as used herein, comprises both unidirectional control and regulation in- eluding one or more feedback loops.

The term "power output level", as used herein, relates to a power level, i.e. output energy per time (usually measured in Watt [W]), supplied by the battery system's battery pack at a given point in time or in a particular mode of operation.

In the following, preferred embodiments, and variants thereof, of the vehicular battery system according to the first aspect of the invention will be described. Unless explicitly excluded or mutually exclusive, those embodiments and variants may be arbitrarily combined with each other and with the second aspect of the invention, as described thereafter.

According to a first preferred embodiment the second mode of operation of the battery system is one of a high power operation mode, a start-up mode and a failure mode. The high power operation mode requires a power output level of the battery pack that is greater than the power level being electrochemically equivalent to the cleaning apparatus' maximum supply rate of cleaned gas in any mode of operation of the battery system. Thus, in this embodiment, the gas reservoir supplies oxygenous gas to the battery pack, when the supply provided by the cleaning apparatus is not sufficient to support a required power output level of the battery pack. The gas stored in the gas reservoir may then be used to supply either all of the oxygen con- sumed by the battery in the high power operation mode, or it may be added to the supply of oxygenous gas provided by the cleaning apparatus in order to increase the total supply rate of oxygen to the battery pack.

During the start-up mode the cleaning apparatus supplies to the battery pack no or at least insufficient oxygen for powering it up to normal operation. Thus, the gas reservoir provides oxygen to the battery pack for powering it up, at least as long as the cleaning apparatus is not yet capable of providing sufficient oxygen to the battery pack for its normal operation, in particular for the first mode of operation. Once the cleaning apparatus is again supplying enough oxygen, the startup mode may be terminated and the gas supply from the gas reservoir may be stopped or at least reduced. Accordingly, the battery system does not depend on external oxygen supply for startup.

In the failure mode, the gas cleaning apparatus is not or at least not fully operable because of a failure and thus cannot provide enough or any cleaned oxygenous gas to the battery pack. Thus, the battery pack is substantially depending on a gas supply from the gas reservoir in order to stay operative to generate electric power.

According to a further preferred embodiment the battery system is operable in the first mode of operation such that the first power output level is lower than the second power level, the cleaning apparatus supplies an excess of cleaned oxygenous gas beyond what is consumed by the battery pack at the first power output level, and said excess of cleaned oxygenous gas is at least partially stored into the gas reservoir. Thus, the excess of cleaned oxygenous gas can be reused in a subsequent second mode of operation of the battery system, where the oxygen supply rate of the cleaning apparatus is less than a required supply rate for that mode.

In particular, according to preferred variants of this embodiment, said first mode of operation may be one of a low-power mode and a shutdown preparation mode. In the low power mode, the power output level is substantially below the second power level. The shut-down preparation mode, is initiated before the battery system is shut down and in this mode enough excess cleaned oxygenous gas is stored into the gas reservoir to allow for starting-up the battery system after shut down with that stored amount of cleaned oxygenous gas. According to a further preferred embodiment the battery system has at least one third mode of operation, during which the battery pack is at least partially charged thereby generating oxygenous gas to be stored gas reservoir. The third mode of operation may be in particular one of a charging mode and a recuperation mode. In the charging mode the battery pack is electrically charged, in particular by applying a suitable external voltage to the terminals of the battery pack, e.g. at a charging station. In the recuperation mode, electric energy is generated by some battery external source and provided to the battery system to store it at least in parts. In particular, the recuperation mode may be selected during a braking phase of a vehicle containing the battery system, where electric energy is recuperated by the vehicle's eddy brakes and provided to the battery pack to at least partially recharge it. During this recharging process oxygen is generated at the cathode side of the battery pack and stored into the gas reservoir and accordingly, as in charging mode, the battery pack does not have to be supplied with oxygenous gas. According to a further preferred embodiment the battery system further comprises one or more sensors configured to detect one or more of the following: the cleaning apparatus' current supply rate of cleaned oxygenous gas, the concentration or amount of 0₂ in the cleaned oxygenous gas provided by the cleaning apparatus, the concentration or amount of 0₂ in the oxygenous gas stored in or provided by the gas reservoir and the concentration or amount of contaminates in the cleaned oxygenous gas provided by the cleaning apparatus. Thus, the sensors provide information, which can be used by the battery management system as input such that the control of the battery system, in particular of the supply of oxygenous gas to the battery pack, may be controlled based thereon. In particular, the information provid- ed by the one or more sensors may be used to select a particular first mode, second or third mode of operation (as described above) of the battery system and to control the supply of oxygenous gas to or from the battery pack accordingly, e.g by opening or closing related valves guiding the flow of oxygenous gas within the battery system. According to a further preferred embodiment the battery management system is configured to control the supply of oxygenous gas to the battery pack such that when the battery system is operated in the second mode and the oxygenous gas in the gas reservoir has a higher oxygen concentration than the gas supplied by clean- ing apparatus, the battery pack is supplied with a mix of cleaned oxygenous gas from the cleaning apparatus and oxygenous gas from the gas reservoir. When a target power output level of the battery back is increased, the ratio of the oxygenous gas from the gas reservoir in the mix is increased respectively to enable the battery pack to output electrical energy at said target power output level. Thus, the gas from the gas reservoir is used to enrich the oxygen content of the gas supply to the battery pack during the second mode of operation. Accordingly, the increase of the power output level of the battery pack can be achieved without merely increasing the gas volume supplied to the battery pack, but instead - at least partially - by increasing the oxygen concentration of the supplied gas. Thus, advantageously a higher maximum power output level can be achieved without a need to increase the size and weight of the gas reservoir.

According to a preferred variant of this embodiment the battery management system is further configured to control the supply of oxygenous gas to the battery pack such that when a target power output level of the battery back is increased above a predetermined value the ratio of the oxygenous gas from the gas reservoir in the mix is essentially 100%. Thus, when in the second mode of operation very high power output levels are required, such as for power output levels close to the maximum power output level of the battery pack, the latter may be solely supplied with be oxygenous gas from the gas reservoir, wherein the gas in the gas reservoir it has a higher oxygen concentration than the gas supplied by the cleaning apparatus and thus enables a higher power level than a mix of gas from the gas reservoir and the cleaning apparatus would. According to a further preferred embodiment the vehicular battery system further comprises at least one blocking device operable to selectively block the supply of oxygenous gas from the gas cleaning apparatus to the battery. In particular, the blocking device may be a switch or a valve. Thus, the blocking device can be used to separate the battery pack from the cleaning apparatus, in particular when it is defect or otherwise non-functional. The battery pack can then be supplied solely with gas from the gas reservoir, e.g. in order to drive the vehicle to a next filling station or repair shop.

According to a further preferred embodiment the vehicular battery system further comprises one or more pressure sensors configured to measure the gas pressure of the oxygenous gas in the gas reservoir and to provide a signal to the battery management system, when a predetermined maximum gas pressure level is achieved while oxygenous gas is being stored into the gas reservoir. Thus, the battery system is enabled to stop a further supply of oxygenous gas to the gas reservoir, in particu- lar during a low-power, charging or recuperation mode, when the gas reservoir has reached the maximum filling level.

According to a further preferred embodiment the vehicular battery system further comprises a compressor configured to compress cleaned oxygenous gas supplied by the cleaning apparatus or oxygenous gas effluent from the battery pack, or both, up to a predetermined maximum gas pressure and to store the compressed oxygenous gas into the gas reservoir. Thus, the battery system may independently store oxygenous gas into the gas reservoir under pressure, in order to increase the storage efficiency of the gas reservoir, i.e. the amount of gas that can be stored therein. In particular, the compressor thus enables the efficient reuse of oxygenous gas generated in the battery pack during charging or recuperation modes and the efficient storing of excess amounts of oxygenous gas provided by the cleaning apparatus during the first mode of operation of the battery system. In a preferred variant of these embodiments the gas reservoir is dimensioned such that the amount of oxygen in the gas reservoir, when completely filled at said maximum gas pressure with substantially pure 0₂ is electrochemically equivalent to a fraction of more than 5% and less than 50%, preferably equivalent to approximately 10%, of the energy storage capacity of the battery pack. In particular, the gas reser- voir may be dimensioned to store a gas volume of 150 liters or less, preferably 100 liters or less. Furthermore, preferably said maximum gas pressure is in the range of 0.1 MPa to 35 MPa, preferably in the range of 0.2 MPa to 5 MPa, more preferably in the range of 0.3 MPa to 1 MPa. These ranges respectively values relate to particularly advantageous dimensions and maximum gas pressures of the gas reservoir relative to the energy storage capacity of the battery pack, where on the one hand the size and weight of the gas reservoir is sufficiently less then it would have to be to support the full energy storage capacity of the battery pack, while it is still sufficiently large, to support a meaningful second mode of operation of the battery system, as e.g. expressed in available driving distance in the second mode of operation. According to a further preferred embodiment the vehicular battery system further comprises a second battery pack which is not of the metal/oxygen type. Thus, a battery system based on different battery technologies can be provided, which combines the advantages of different battery types in one system. In particular, the second battery pack may be a conventional lithium-ion type battery as is common in today's electrical and hybrid cars. In such a combined system the metal/oxygen battery pack provides its above-mentioned advantages, when oxygen supply is available, while the conventional battery system is still available to supply electricity, if the metal/oxygen type battery pack runs out of oxygen without adequate supply of oxygenous gas being available.

A second aspect of the invention is directed to a method of operating a vehicular battery system according to the first aspect. The method comprises operating the battery management system to control the supply of oxygenous gas to the battery pack such that when the battery system is operated in the first mode, the battery pack is supplied with oxygenous gas output by the cleaning apparatus, and when the battery system is operated the second mode, the battery pack is additionally or instead supplied with oxygenous gas from the gas reservoir.

Accordingly, the various embodiments and variants and advantages described above in relation to the first aspect of the invention apply similarly to the second aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages, features and applications of the present invention are provided in the following detailed description in connection with the figures, wherein:

Fig. 1 illustrates schematically a vehicular battery system according to a preferred embodiment of the present invention; Fig. 2 illustrates schematically a startup mode of operation of the vehicular battery system of Fig. 1 , according to a preferred embodiment of the present invention;

Fig. 3 illustrates schematically a low-power mode of operation of the vehicular battery system of Fig. 1 , according to a preferred embodiment of the present invention;

Fig. 4 illustrates schematically a high-power mode of operation of the vehicular battery system of Fig. 1 , according to a preferred embodiment of the present invention;

Fig. 5 illustrates schematically a charging mode of operation of the vehicular battery system of Fig. 1 , according to a preferred embodiment of the present invention;

Fig. 6 illustrates schematically a recuperation mode of operation of the vehicular battery system of Fig. 1 , according to a preferred embodiment of the pre- sent invention;

Fig. 7 illustrates schematically a shut-down preparation mode of operation of the vehicular battery system of Fig. 1 , according to a preferred embodiment of the present invention;

Fig. 8 illustrates a flow chart of a method of operating the vehicular battery system of Fig. 1 , according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS At first, reference is made to Fig. 1 , which shows a vehicular battery system 1 according to a preferred exemplary, non-limiting embodiment of the present invention. The battery system 1 comprises a metal/oxygen-type battery pack 2, a gas reservoir 3 for holding oxygenous gas under pressure, a compressor 4 for compressing such gas and filling the gas reservoir 3 with it, a cleaning apparatus 5 for cleaning gas - in particular ambient air - received through an inlet 8, and a battery management system 6.

The battery pack 2 comprises at least one battery cell (as drawn) having an anode A made of or comprising a suitable metal, preferably lithium. Alternatively, the anode A can also be made of a conductive, non-metallic material. The battery pack 2 further comprises a cathode C which uses oxygen from the oxygenous gas as its electrochemical component. To that purpose, the cathode C comprises a porous material, preferably mesoporous carbon with metal catalysts, and is electrically connected to a current collector CC for conducting charges to or from the cathode C to a cathode connector of the battery cell. The anode side and the cathode side of the battery cell are separated by a separator S. The cell further comprises an electrolyte, preferably in solid form, such as a ceramic, glass, or glass-ceramic electrolyte. In some embodiments the electrolyte is combined with the separator S into one part. Alterna- tively, also other forms of electrolyte are possible, in particular 2 aprotic, aqueous or mixed aqueous/aprotic forms. In practice, the battery pack 2 will typically comprise a plurality of similar battery cells (not drawn) of the type described above, which are connected in series or parallel, or some combination of it. The battery pack 2 has an energy storage capacity, which defines the amount of electrical energy the battery pack 2 can store.

The gas reservoir 3 is a gas pressure tank, which is on the one hand fluidly connected via a valve V1 to the cathode side of the battery pack 2. On the other hand, the gas reservoir 3 is fluidly connected via a valve V3 to the compressor 4. In addi- tion, the gas reservoir 3 may have an inlet 7 sealed by a further valve or sealing V7 through which it can be directly filled with gas from a battery-external source of - preferably pressurized - oxygenous gas. The gas tank is designed to contain oxygenous gas having an oxygen concentration (0₂) of up to 100% at a pressure up to a maximum gas pressure which is in the range of 0.1 MPa to 35 MPa, preferably in the range of 0.2 MPa to 5 MPa, more preferably in the range of 0.3 MPa to 1 MPa. In one exemplary variant the gas storage volume of the gas reservoir 3 is approximately 100 liters.

The compressor 4 is adapted to receive gas, in particular oxygenous gas from the cleaning apparatus 5 to which it is fluidly connected via a further valve V4. The compressor 4 is configure to compress the received gas up to a pressure level being less than or equal to said maximum gas pressure of the gas reservoir 3. In addition, an inlet of the compressor 4 is fluidly connected via a further valve V2 to the cathode side of the battery pack 2, in order to receive therefrom oxygenous gas being gen- erated during a charging or recuperation mode of operation, compress said gas and store it into the gas reservoir 3, as will be explained in more detail below. The cleaning apparatus 5 is an active electrically powered system for cleaning gas, - in particular ambient air - received through a inlet 8 from contaminants, such as moisture, dirt particles and C0₂. The inlet 8 can be sealed by a further valve V6, when not in use. In particular, the cleaning apparatus may comprise an electric pump for generating a flow of the to-be-cleaned gas through filter material and/or an area exposed to an electric field for removing charged particles. The cleaning apparatus is powered by electric energy provided by the battery pack 2. An outlet of the cleaning apparatus is fluidly connected via a further valve V5 to the cathode side of the battery pack 2 in order to supply it with cleaned oxygenous gas during selected modes of operation of the battery system, as described in detail below.

In addition, the battery system comprises sensors 9, 10 and 1 1. In particular, each of the sensors may be itself a sensor system comprising multiple individual sensors of a same or a different type. Sensor 9, which is located inside the gas reservoir 3 is adapted to measure the concentration or amount of 0₂ in the oxygenous gas stored in or provided by the gas reservoir and its pressure. Sensor 10 is located in the fluid connection path between the compressor 4 and the gas reservoir 3 and is adapted to measure the cleaning apparatus' current supply rate of cleaned oxygenous gas and the concentration or amount of 0₂ therein. Sensor 1 1 is located in the fluid connection path between the cleaning apparatus and the cathode side of the battery pack 2. It is adapted to measure the concentration or amount of 0₂ in the oxygenous gas provided by the cleaning apparatus to the battery pack during respective modes of operation. Furthermore, sensors 10 and 1 1 are adapted to measure the concen- tration or amount of contaminates in the cleaned oxygenous gas provided by the cleaning apparatus to the gas reservoir 3 respectively the battery pack 2._.

The battery system 6 comprises one or more control units configured to control the battery system. The battery system is in communication (not drawn), e.g. via cables, optical fiber or wirelessly, with one or more other components of the battery system 1 , in particular with the cleaning apparatus 5, the valves V1 to V7 and the sensors 9 to 1 1 . In particular, the battery system 6 is configured to receive signals carrying measurement data from one or more of the sensors 9 to 1 1 and status information (e.g. "open" or "closed") from one or more of the valves V1 to V7. The battery man- agement system 6 is further configured to sent control signals to one or more of the valves V1 to V7 to switch them into an open respectively closed state, to the cleaning apparatus 5 and to the compressor 4 to control their respective operation.

The battery system 1 also comprises a second battery pack 12 which, unlike battery pack 2, is not of the metal/oxygen type and has an anode A2, a cathode C2 and a separator S2 separating the anode side from the cathode side, as is usual for many types of battery cells including lithium-ion cells. The second battery pack may be advantageously used to increase the overall battery capacity available to a vehicle and to extend its range, in particular, if the metal/oxygen battery system 1 fails, e.g. when its cleaning apparatus 5 is defect and the content of the gas reservoir 3 is exhausted.

Figs. 2 to 7 illustrate various different modes of operation of the battery system of Fig.1. In particular, Fig. 2 illustrates a startup mode of the battery system, wherein the battery management system 6 controls the battery system 1 such that oxygenous gas from the gas reservoir 3 is provided through the open valve V1 to the cathode side of the battery pack 2, thus triggering its operation to provide electrical energy by known chemical reactions taking place within the battery pack 2. During this mode, initially the cleaning apparatus 5 and the compressor 4 are waiting for the battery pack 2 to provide enough electrical power for the cleaning apparatus 5 and the compressor 4 to begin their operation to supply the battery pack with cleaned oxygenous gas from a battery external gas source, such as the earth's atmosphere.

Another mode of operation of the battery system 1 is a failure mode, which is en- tered if the cleaning apparatus 5 is not functional, e.g. if defect. The battery system 1 is then controlled by the battery management system 6 in a similar way as illustrated in figure 2, i.e. the battery pack 2 is solely supplied with oxygenous gas from the gas reservoir 3, while the fluid connection to the cleaning apparatus 5 is blocked (valve V5 closed) and both the compressor 4 and the cleaning apparatus 5 are inac- tive. This mode is in particular suitable for enabling the battery system 2 to power the vehicle sufficiently to reach at least an intermediate destination, such as a repair shop, when the cleaning apparatus 5 fails during driving.

Typically, the battery system 1 will transition under the control of the battery man- agement system 6 from the startup mode of Fig. 2 to the low-power mode illustrated in Fig. 3. After this transition, the fluid connection between the gas reservoir 3 and the battery pack 2 is disconnected (valve V1 closed) and the oxygenous gas necessary for the operation of the battery pack 2 is provided by the cleaning apparatus 5 (valves V5 and V6 open), which in turn is powered by electrical energy provided by the battery pack 2. When in this low-power mode the cleaning apparatus' supply rate of oxygenous gas is higher than that required by the battery pack 2, the excess cleaned gas provided by the cleaning apparatus 5 is compressed by the compressor 4 and stored into the gas reservoir 3 for future use (valves V3 and V4 open).

When the battery pack 2 is required to provide more electrical power, e.g. for a strong acceleration of the vehicle, the battery system 1 is controlled by the battery management system 6 to enter a high power mode of operation, which is illustrated in Fig. 4. Here the battery pack 2 is supplied with oxygenous gas both from the gas reservoir 3 (in particular with oxygen enriched air or even pure oxygen) and from the cleaning apparatus 5 (valves V1 , V5, V6 open). Thus, the supply of the battery pack 2 with oxygen is increased such that it can increase its output of electrical power up to a maximum.

Fig. 5 illustrates a charging mode of operation of the battery system 1 , where a suitable external voltage, e.g. provided by a vehicle external charging station, is applied between the anode side and the cathode side of the battery pack 2 to recharge the battery. The chemical reactions taking place in the battery pack 2 during the charging generate oxygen (0₂) at the cathode side which is guided through the compressor 4 (valve V2 open), compressed, and stored into the gas reservoir 3 (valve V3 open) for future use. Optionally (not drawn), in addition the gas reservoir 3 may be refilled with - typically pressurized - oxygenous gas through inlet 7 (valve V7 open).

Fig. 6 illustrates a recuperation mode of operation of the battery system 1 . A recuperation mode is a mode where one or more components of a vehicle, in particular eddy current brakes, generate electric energy and provide same to the battery pack 2 for at least partially recharging it while the vehicle is operated. Similarly, as in the charging mode of operation of Fig. 5, oxygen is generated at the cathode side of the battery pack 2, guided to the compressor 4, compressed, and stored into the gas reservoir 3. In addition, however, also the cleaning apparatus 5 is active and providing cleaned oxygenous gas to the compressor 4 in order for it to be stored into the gas reservoir 3. In other words, unlike in the charging mode of Fig. 5, the continuous operation of the battery system 1 is maintained (e.g. corresponding to a low-power mode), while in addition - at least for short periods of time, such as braking periods - oxygenous gas generated at the cathode side of the battery pack 2 is additionally stored into the gas reservoir 3. Finally, Fig. 7 illustrates a shutdown preparation mode of the battery system 1 of Fig. 1. This mode is similar to the low-power mode illustrated in Fig. 3. The shutdown preparation mode is entered shortly before the battery system is shut down, e.g. when the vehicle powered by the battery system 1 is parked. The shutdown preparation mode is active at least as long as is necessary to store enough oxyge- nous gas into the gas reservoir 3 for enabling a subsequent startup mode. One or more of sensors 9 to 1 1 measure the amount or concentration of oxygenous gas being already present respectively being supplied to the gas reservoir 3 and the measurement results are provided to the battery management system via respective signals.

Reference is now also made to Fig. 8, which generally illustrates a preferred embodiment of the method according to the second aspect of the invention. In particular, the method is described in connection with the exemplary vehicular battery system of Fig. 1 and its modes of operation as illustrated in detail in Figs. 2 to 7. In a first step S1 the battery management system receives signals from a signal source, such as a controller of the vehicle comprising the battery system 1 , the signals carrying information relating to a mode of operation to be entered by the battery system 1 . In addition or in the alternative the battery management system 6 may receive signals from one or more of sensors 9 to 1 1 or other sensors, from which signals it derives a mode of operation to be entered. In case the battery management system 6 receives both signals from the controller of the vehicle and from one or more of the sensors, the sensor data may be used in particular to verify, whether the mode indicated in the signal received from the controller is consistent with the measurements indicated in the sensor signals. A change of mode of operation may then only be initiated, if there is sufficient consistency. Otherwise, the current mode may be maintained and optionally an error signal may be issued.

Once a signal indicating that a new mode of operation is to be entered by the battery system 1 , is successfully received and/or verified, in a second step S2 the battery management system 6 causes the battery system to transition to that selected mode of operation. If the selected mode of operation corresponds to a first mode of opera- tion, i.e. a mode of operation where the supply rate of oxygenous gas of the cleaning apparatus is sufficient to supply the battery pack 2 or to a third mode of operation, i.e. a mode where no such supply of oxygenous gas to the battery pack 2 is necessary at all, valve V1 is controlled to be closed such that no gas is supplied from the gas reservoir 3 to the battery pack 2. On the other hand, if the selected mode of operation does not correspond to a first mode but rather to a second mode of operation, i.e. a mode of operation where the battery pack 2 needs to be supplied - at least in addition - with oxygenous gas from the gas reservoir 3, valve V1 is controlled to be open such that oxygenous gas from the gas reservoir 3 can flow to the cathode side of the battery pack 2 such that the chemical reactions responsible for generating electric energy can take place. Once a new mode of operation has been entered, the control group returns to step S1. The various modes of operation indicated in Fig. 8 have already been illustrated and discussed in detail above in connection with Figs. 2 to 7.

While above at least one exemplary embodiment has been described, it has to be noted that a great number of variations thereto exists. It is also noted that the described exemplary embodiments represent only non-limiting examples and that it is not intended that the scope, the applicability or the configuration of the here- described apparatus and methods is thereby limited. Rather, the preceding description will provide the person skilled in the art with directions for the implementation of at least one of the exemplary embodiments, while it has to be appreciated that various different modifications of the functionality and the arrangement of the elements described in connection with the exemplary embodiments may be made without deviating from the scope of the invention as defined in the appended claims and its legal equivalents.

LIST OF REFERENCE SIGNS

1 vehicular battery system

2 metal/oxygen battery pack

3 gas reservoir

4 compressor

5 cleaning apparatus

6 battery management system

7 gas reservoir inlet (for receiving gas from battery external source) 8 cleaning apparatus inlet (for receiving gas from battery external source)

9 - 1 1 sensors

12 second battery pack

V1 -V5 valves

A anode of metal/oxygen battery pack

C cathode of metal/oxygen battery pack

CC current collector of the cathode C

S separator of metal/oxygen battery pack

A1 anode of second battery pack

C1 cathode of second battery pack

S1 separator of second battery pack

Claims

A vehicular battery system (1 ), comprising:

a metal/gas battery pack (2) configured to output electrical power;

a gas reservoir (3) configured to store oxygenous gas and being operatively coupled to the battery pack (2) to supply oxygenous gas to said battery pack

(2);

a gas cleaning apparatus (5) configured to receive oxygenous gas, in particular ambient air, to clean said gas from contaminants and to supply the cleaned oxygenous gas to said battery pack (2); and

a battery management system (6) configured to control the supply of oxygenous gas from the cleaning apparatus (5) and the gas reservoir (3) to the battery pack (2);

wherein the battery system (1 ) has at least two modes of operation, including: a first mode that requires a first power output level lower than or equal to a second power level being electrochemically equivalent to the cleaning apparatus' (5) maximum supply rate of oxygen in said first mode of operation, and at least one second mode that requires a third power output level greater than the second power level; and

wherein the battery management system (6) is configured to control the supply of oxygenous gas to the battery pack (2) such that when the battery system (1 ) is operated in the first mode, the battery pack (2) is supplied with oxygenous gas output by the cleaning apparatus (5), and when the battery system (1 ) is operated in the second mode, the battery pack (2) is additionally or instead supplied with oxygenous gas from the gas reservoir (3).

The vehicular battery system (1 ) of claim 1 , wherein the second mode of operation of the battery system (1 ) is one of the following:

- a high power operation mode requiring a power output level of the battery pack (2) that is greater than the power level being electrochemically equivalent to the cleaning apparatus' (5) maximum supply rate of cleaned gas in any mode of operation of the battery system (1 );

- a start-up mode, during which the cleaning apparatus (5) supplies to the battery back (2) no or at least insufficient oxygen for powering it up to normal operation; - a failure mode, where the gas cleaning apparatus is not or at least not fully operable because of a failure.

The vehicular battery system (1 ) of any one of the preceding claims, wherein the battery system (1 ) is operable in the first mode of operation such that: the first power output level is lower than the second power level;

the cleaning apparatus (5) supplies an excess of cleaned oxygenous gas beyond what is consumed by the battery pack (2) at the first power output level; and

said excess of cleaned oxygenous gas is at least partially stored into the gas reservoir (3).

The vehicular battery system (1 ) of claim 3, wherein said first mode of operation is one of the following:

a low power mode, where the power output level is substantially below the second power level;

a shut-down preparation mode, which is initiated before the battery system (2) is shut down and wherein enough excess cleaned oxygenous gas is stored into the gas reservoir (3) to allow for starting up the battery system (1 ) after shut down with that stored amount of cleaned oxygenous gas;

The vehicular battery system (1 ) of any one of the preceding claims, wherein the battery system (1 ) has at least one third mode of operation, during which the battery pack (2) is at least partially charged thereby generating oxygenous gas to be stored gas reservoir (3).

The vehicular battery system (1 ) of any one of the preceding claims, wherein the battery system (1 ) further comprises one or more sensors (9, 10, 1 1 ) configured to detect one or more of the following:

- the cleaning apparatus' (5) current supply rate of cleaned oxygenous gas;

- the concentration or amount of 0₂ in the cleaned oxygenous gas provided by the cleaning apparatus (5)_;

- the concentration or amount of 0₂ in the oxygenous gas stored in or provided by the gas reservoir (3)_;

- the concentration or amount of contaminates in the cleaned oxygenous gas provided by the cleaning apparatus (5)_.

The vehicular battery system (1 ) of any one of the preceding claims, wherein the battery management system (6) is configured to control the supply of oxygenous gas to the battery pack (2) such that when the battery system (1 ) is operated in the second mode and the oxygenous gas in the gas reservoir (3) has a higher oxygen concentration than the gas supplied by cleaning apparatus (5), the battery pack (2) is supplied with a mix of cleaned oxygenous gas from the cleaning apparatus (5) and oxygenous gas from the gas reservoir (3), wherein when a target power output level of the battery back (2) is increased the ratio of the oxygenous gas from the gas reservoir (3) in the mix is respectively increased to enable the battery pack (2) to output electrical energy at said target power output level.

The vehicular battery system (1 ) of claim 7, wherein the battery management system (6) is further configured to control the supply of oxygenous gas to the battery pack (2) such that when a target power output level of the battery back is increased above a predetermined value the ratio of the oxygenous gas from the gas reservoir (3) in the mix is essentially 100%.

The vehicular battery system (1 ) of any one of the preceding claims, further comprising one or more pressure sensors (9,

10,

1 1 ) configured to measure the gas pressure of the oxygenous gas in the gas reservoir (3) and to provide a signal to the battery management system (6), when a predetermined maximum gas pressure level is achieved while oxygenous gas is being stored into the gas reservoir (3).

The vehicular battery system (1 ) of any one of the preceding claims, further comprising a compressor (4) configured to compress cleaned oxygenous gas supplied by the cleaning apparatus (5) or oxygenous gas effluent from the battery pack (2), or both, up to a predetermined maximum gas pressure and to store the compressed oxygenous gas into the gas reservoir (3).

The vehicular battery system (1 ) of claim 9 or 10, wherein the gas reservoir (3) is dimensioned such that the amount of oxygen in the gas reservoir (3), when completely filled at said maximum gas pressure with substantially pure 0₂ is electrochemically equivalent to a fraction of more than 5% and less than 50%, preferably equivalent to approximately 10%, of the energy storage capacity of the battery pack (2).

12. The vehicular battery system (1 ) of any one of claims 9 to 1 1 wherein said maximum gas pressure is in the range of 0.1 MPa to 35 MPa, preferably in the range of 0.2 MPa to 5 MPa, more preferably in the range of 0.3 MPa to 1 MPa.

13. The vehicular battery system (1 ) of any one of the preceding claims, wherein the gas reservoir (3) is dimensioned to store a gas volume of 150 liters or less, preferably 100 liters or less.

14. The vehicular battery system (1 ) of any one of the preceding claims, further comprising a second battery pack (12) that is not of the metal/oxygen type.

15. A method of operating a vehicular battery system (1 ) according to any one of the preceding claims, the method comprising:

operating the battery management system (6) to control the supply of oxygenous gas to the battery pack (2) such that when the battery system is operated in the first mode, the battery pack (2) is supplied with oxygenous gas output by the cleaning apparatus (5), and when the battery system is operated the second mode, the battery pack (2) is additionally or instead supplied with oxygenous gas from the gas reservoir (3).