Fuel cell low-temperature shutdown purging method, device and system, cell and carrier

Abstract

The invention discloses a fuel cell low-temperature shutdown purging method, device and system, a cell and a carrier, and the purging method at least comprises the following steps: the fuel cell runs with 0.15-0.18 standard current density, ventilation and gas flow control correspond to gas flow under 1.2-1.4 standard current density, the temperature of an electric pile cooling liquid outlet is controlled to be maintained at 60-65 DEG C, the fuel cell is subjected to low-temperature shutdown purging, and the fuel cell is subjected to low-temperature shutdown purging. When the average voltage is less than or equal to 0.7 V, carrying out load reduction; after the load is reduced to 0.03-0.04 standard current density, the gas flow is set to be 0.03-0.04 standard current density, then air supply is closed, and when the average voltage of the single body is reduced to be not higher than V0, load current and hydrogen supply are closed; when the temperature of an electric pile cooling liquid outlet is reduced to 5-20 DEG C, the gas flow is set to be 0.05-0.3 standard current density, and on-load purging is not carried out; and when the average voltage of the monomer is not higher than V0, loading again to 0.03-0.04 standard current density, setting the gas flow to 0.03-0.04 standard current density, then closing the air supply, and when the average voltage of the monomer is reduced to be not higher than V0, closing the load current and closing the hydrogen supply. According to the invention, the initial water content of the electric pile can be effectively reduced, and liquid water condensed by water vapor in the electric pile due to cooling can also be effectively removed.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell low-temperature shutdown purge method, device, system, battery and carrier. Background Art

[0002] With the rapid development of hydrogen energy technology and the large-scale application of proton exchange membrane fuel cells (PEMFCs), their low-temperature cold start performance has become a core bottleneck restricting commercialization. The key to solving this problem is the dynamic correlation mechanism between the low-temperature purge step and the cold start process. By precisely controlling the initial water content of the membrane electrode, the purge step effectively prevents residual liquid water from freezing and clogging the flow channel at low temperatures after shutdown. It also provides an appropriate water supply for the electrochemical reaction in the initial cold start, thereby suppressing ice crystal growth while maintaining proton conduction efficiency. The optimized purge strategy can significantly improve the cold start success rate and shorten the start-up time at -30°C.

[0003] Currently, a low-current, loaded purge method, typically employed during air blast purge, is commonly used. Existing methods that directly purge to the target high-frequency impedance value suffer from long purge times (causing the proton exchange membrane to dry out) and high hydrogen consumption. Furthermore, traditional purge strategies fail to consider the impact of internal temperature gradients on water condensation, causing residual liquid water to freeze at low temperatures and block the flow path.

[0004] Therefore, in order to solve the above technical problems, it is necessary to provide a fuel cell low-temperature shutdown purge method, device, system, battery and carrier.

[0005] The information disclosed in this background section is only intended to enhance understanding of the overall background of the invention and should not be considered as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the Invention

[0006] The object of the present invention is to provide a fuel cell low-temperature shutdown purge method, device, system, battery and carrier.

[0007] In order to achieve the above object, a specific embodiment of the present invention provides the following technical solutions:

[0008] The fuel cell low-temperature shutdown purge method determines whether the purge is successful after the following purge work is completed. If so, the purge is completed. Otherwise, the purge is repeated. The judgment standard is: after the purge is completed, the internal resistance value R1 of the fuel cell stack after standing for 10-30 minutes is obtained. When R1 ≥ the preset internal resistance value R0, the fuel cell stack purge is confirmed to be successful, otherwise it fails. The purge work includes at least the following steps:

[0009] Step (1), the fuel cell is operated with a load of 0.15-0.18 standard current density, dry hydrogen and dry air are introduced into the anode and cathode respectively, the gas flow rate corresponds to the gas flow rate at a standard current density of 1.2-1.4, the outlet temperature of the stack coolant is controlled to be maintained at 60-65°C, and the load is reduced when the average voltage of the single cell is less than or equal to 0.7V; Step (2), when the load is reduced to 0.03-0.04 standard current density, the gas supply is restored, and the gas flow rate is set to a flow rate of 0.03-0.04 standard current density, and then the air supply is turned off. When the average voltage of the single cell drops to no more than V0, the load current is turned off and the hydrogen supply is turned off;

[0010] Step (3), after the outlet temperature of the stack coolant drops to 5-20°C, resume gas supply, set the gas flow rate to a flow rate of 0.05-0.3 standard current density, and set the no-load purge time to 10-20 seconds;

[0011] Step (4), reload to 0.03-0.04 standard current density, set the gas flow rate to 0.03-0.04 standard current density, then turn off the air supply, and when the average voltage of the monomer drops to no more than V0, turn off the load current and the hydrogen supply;

[0012] Where V0 is 0.15-0.35V.

[0013] In one or more embodiments of the present invention, the preset internal resistance value R0 is 2-5 times the wet state internal resistance r.

[0014] In one or more embodiments of the present invention, in at least any one of steps (1) to (4): the pressure of the gas introduced into the anode is 30 kPa-40 kPa; and / or the pressure of the gas introduced into the cathode is 35 kPa-45 kPa.

[0015] In one or more embodiments of the present invention, in steps (1) to (4): the pressure of the gas introduced into the anode remains unchanged; and / or the pressure of the gas introduced into the cathode remains unchanged.

[0016] In one or more embodiments of the present invention, in steps (1) to (4): the gas introduced into the anode is preheated; and / or the gas introduced into the cathode is preheated.

[0017] In one or more embodiments of the present invention, preheating is to adjust the gas temperature to 5-65°C.

[0018] In one or more embodiments of the present invention, in steps (1) to (4): the gas introduced into the anode is preheated and has a uniform temperature; and / or the gas introduced into the cathode is preheated and has a uniform temperature.

[0019] In one or more embodiments of the present invention, in step (2) and / or step (4): after the air supply is turned off, the time for the average voltage of the fuel cell to drop from the purge voltage to V0 is 5 to 20 seconds.

[0020] In one or more embodiments of the present invention, the purge device implements the fuel cell low-temperature shutdown purge method according to any one of claims 1-8.

[0021] In one or more embodiments of the present invention, a purge system includes a carrying body and a plurality of purge devices disposed on the carrying body.

[0022] In one or more embodiments of the present invention, a battery system includes a plurality of battery stacks and a purge system for purging the battery stacks before shutdown according to instructions.

[0023] In one or more embodiments of the present invention, a vehicle includes a power system, and the power system includes a battery system.

[0024] Compared with the prior art, the fuel cell low-temperature shutdown purge method, device, system, battery and carrier of the present invention can effectively reduce the initial water content of the fuel cell stack, and can also effectively remove the liquid water condensed into water vapor inside the fuel cell stack due to cooling. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is a graph showing the change in high-frequency impedance of the proton exchange membrane over time during the purge and water removal process in Example 1 of the present invention;

[0027] Figure 2 This is a graph showing the change in average voltage of the stack over time during the purge and water removal process in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] The low-temperature shutdown purging method for a fuel cell of the present invention comprises the following steps:

[0030] Step (1), the fuel cell is operated at a standard current density of 0.15-0.18, dry hydrogen and dry air are introduced into the anode and cathode respectively, the gas flow rate corresponds to the gas flow rate at a standard current density of 1.2-1.4, the outlet temperature of the stack coolant is controlled to be maintained at 60-65°C, and the load is reduced when the average voltage of the cells is less than or equal to 0.7V;

[0031] Step (2): reduce the load to 0.03-0.04 standard current density, set the gas flow rate to 0.03-0.04 standard current density, and then turn off the air supply. When the average voltage of the monomer is less than 0.15-0.35V, turn off the load current and the hydrogen supply;

[0032] Step (3), wait for the stack coolant outlet temperature to drop to 5-20°C, restore the gas supply, set the gas flow rate to 0.05-0.3 standard current density, and set the no-load purge time to 10-20 seconds;

[0033] Step (4): load to 0.03-0.04 standard current density, set the gas flow rate to 0.03-0.04 standard current density, then turn off the air supply, and when the average cell voltage is less than 0.15-0.35V, turn off the load current and the hydrogen supply.

[0034] As a preferred solution, after the above steps are completed, the internal resistance value R1 of the battery stack is obtained after standing for 10-30 minutes. When the internal resistance value R1 ≥ R0, it is confirmed that the battery stack purge is successful; when the internal resistance value is less than the preset final internal resistance value, it is confirmed that the battery stack purge has failed.

[0035] As a preferred solution, the preset internal resistance value R0 is 2-5 times the wet state internal resistance r.

[0036] As a preferred solution, in steps (1) to (4), the following conditions are met: the pressures of the gases at the anode and cathode are 30 kPa-40 kPa and 35 kPa-45 kPa, respectively.

[0037] As a preferred embodiment, in steps (1) to (4), the following conditions are met: hydrogen and / or air are preheated.

[0038] As a preferred solution, in steps (1) to (4), the following conditions are met: the temperature range of the preheated hydrogen and / or air is 5-65°C.

[0039] As a preferred solution, after the air supply is turned off in step (2) and step (4), the time for the average voltage of the fuel cell to drop from the purge voltage to an average voltage of less than 0.15-0.35V is 5 to 20 seconds.

[0040] Including but not limited to the following embodiments, the settings for gas flow are all set simultaneously for the anode and cathode gas flows.

[0041] Example 1

[0042] In this example, 500 active sections with an area of ​​350 cm 2 The low-temperature purge steps for the fuel cell stack (water-cooled fuel cell stack, the same below) are as follows: The fuel cell is set to operate at a standard current density of 0.15. During this period, dry, unheated hydrogen and air are introduced into the anode and cathode of the battery, respectively. The flow rate of the cathode and cathode gases corresponds to the gas flow rate at a standard current density of 1.4. The pressures of the cathode and cathode gases are 30 and 35 kPa, respectively (the same gas supply pressure is used in all the following stages, the same below). At the same time, the stack coolant outlet temperature is controlled to maintain at 60°C. When the average voltage of the cells is equal to 0.7V, the load is reduced. Under a load of 0.03 standard current density, the control system sets the gas flow rate to 0.03 standard current density, then shuts off the air supply to consume the residual oxygen remaining in the cathode. When the average voltage reaches 0.35V, the load current is shut off and the hydrogen supply is shut off. Wait for the stack coolant outlet temperature to drop to 5°C, resume the gas supply, set the gas flow rate to 0.05 standard current density, and set the unloaded purge time to 10 seconds. Load to 0.03 standard current density, set the gas flow rate to 0.03 standard current density, then turn off the air supply. When the average cell voltage is 0.35V, turn off the load current and the hydrogen supply. During the purge, AC impedance is used to monitor the water content in the stack and calculate the internal resistance of the stack, including the wet internal resistance of the stack when idling and the internal resistance of the stack after standing for 30 minutes after the purge operation. After the stack is purged, the internal resistance of the stack after standing for 30 minutes is 3.4 times the wet internal resistance, confirming that the stack purge is successful.

[0043] The following table shows the corresponding purge gas flow rate at different current densities

[0044]

[0045] Example 2

[0046] In this example, 500 active sections with an area of ​​350 cm 2The low-temperature purge steps of the fuel cell stack (water-cooled fuel cell stack, the same below) are as follows: the fuel cell is set to operate under the condition of 0.18 standard current density. During this period, dry, unheated hydrogen and air are respectively introduced into the anode and cathode of the battery. The flow rate of the cathode and cathode gases corresponds to the gas flow rate at 1.2 standard current density. The pressures of the cathode and cathode gases are 40 and 45 kPa respectively (the same gas supply pressure is used in the following stages, the same below). At the same time, the outlet temperature of the stack coolant is controlled to maintain at 65°C. When the average voltage of the single cell is equal to 0.7V, the load is reduced. The control system is under a load of 0.04 standard current density and the gas flow rate is set to 0.04 standard current density. Then the air supply is turned off to consume the residual oxygen remaining in the cathode. When the average voltage is 0.35V, the load current is turned off and the hydrogen supply is turned off. Wait for the outlet temperature of the stack coolant to drop to 20°C, set the gas flow rate to 0.3 standard current density, and set the unloaded purge time to 20 seconds. Load to 0.03 standard current density, set the gas flow rate to 0.03 standard current density, then turn off the air supply. When the average cell voltage is 0.35V, turn off the load current and the hydrogen supply. During the purge, AC impedance is used to monitor the water content in the stack and calculate the internal resistance of the stack, including the wet internal resistance of the stack when idling and the internal resistance of the stack after standing for 10 minutes after the purge operation. After the stack is purged, the internal resistance of the stack is 4.5 times the wet internal resistance after standing for 10 minutes, confirming that the stack purge is successful.

[0047] Example 3

[0048] In this example, 500 active sections with an area of ​​350 cm 2The low-temperature purge steps of the fuel cell stack (water-cooled fuel cell stack, the same below) are as follows: the fuel cell is set to operate under the condition of 0.16 standard current density. During this period, dry, unheated hydrogen and air are respectively introduced into the anode and cathode of the battery. The flow rate of the cathode and cathode gases corresponds to the gas flow rate at 1.1 standard current density. The pressures of the cathode and cathode gases are 40 and 45 kPa respectively (the same gas supply pressure is used in the following stages, the same below). At the same time, the outlet temperature of the stack coolant is controlled to maintain at 63°C. When the average voltage of the single cell is equal to 0.7V, the load is reduced. Under the load of 0.04 standard current density, the control system sets the gas flow rate to 0.04 standard current density, then turns off the air supply to consume the residual oxygen remaining in the cathode. When the average voltage is 0.3V, the load current is turned off and the hydrogen supply is turned off. Wait for the outlet temperature of the stack coolant to drop to 10°C, set the gas flow rate to 0.3 standard current density, and set the unloaded purge time to 15 seconds. Load to 0.03 standard current density, set the gas flow rate to 0.03 standard current density, then turn off the air supply. When the average cell voltage is 0.3V, turn off the load current and the hydrogen supply. During the purge, AC impedance is used to monitor the water content in the stack and calculate the internal resistance of the stack, including the wet internal resistance of the stack when idling and the internal resistance of the stack after standing for 20 minutes after the purge operation. After the stack is purged, the internal resistance of the stack after standing for 20 minutes is 4.1 times the wet internal resistance, confirming that the stack purge is successful.

[0049] Example 4

[0050] The only difference between this embodiment and embodiment 3 is that hydrogen and air dried and preheated to 5° C. are introduced into the anode and cathode of the battery respectively.

[0051] After the stack was purged, the internal resistance of the stack was 4.2 times the wet state internal resistance after standing for 20 minutes, confirming that the stack was successfully purged.

[0052] Example 5

[0053] The only difference between this embodiment and embodiment 3 is that hydrogen and air dried and preheated to 35° C. are introduced into the anode and cathode of the battery respectively.

[0054] After the stack was purged, the internal resistance of the stack was 4.5 times the wet state internal resistance after standing for 20 minutes, confirming that the stack was successfully purged.

[0055] Example 6

[0056] The only difference between this embodiment and embodiment 3 is that hydrogen and air dried and preheated to 65° C. are introduced into the anode and cathode of the battery respectively.

[0057] After the stack was purged, the internal resistance of the stack was 4.8 times the wet state internal resistance after standing for 20 minutes, confirming that the stack was successfully purged.

[0058] Example 7

[0059] The only difference between this embodiment and embodiment 3 is that the pressures of the gases at the anode and cathode are 35 kPa and 40 kPa, respectively.

[0060] After the stack was purged, the internal resistance of the stack was 3.9 times the wet state internal resistance after standing for 20 minutes, confirming that the stack was successfully purged.

[0061] Example 8

[0062] The only difference between this embodiment and embodiment 3 is that the pressures of the gases at the anode and cathode are 30 kPa and 35 kPa respectively.

[0063] After the stack was purged, the internal resistance of the stack was 3.6 times the wet state internal resistance after standing for 20 minutes, confirming that the stack was successfully purged.

[0064] Example 9

[0065] The only difference between this embodiment and embodiment 5 is that the pressures of the gases at the anode and cathode are 35 kPa and 40 kPa, respectively.

[0066] After the stack was purged, the internal resistance of the stack was 4.2 times the wet state internal resistance after standing for 20 minutes, confirming that the stack was successfully purged.

[0067] Comparative Example 1

[0068] The only difference between this comparative example and Example 3 is that: 500 active sections with an area of ​​350 cm 2 The low-temperature purge steps of the fuel cell stack (water-cooled fuel cell stack, the same below) are as follows: the fuel cell is set to operate under the condition of 0.16 standard current density, during which dry, unheated hydrogen and air are respectively introduced into the anode and cathode of the battery. The flow rate of the anode and cathode gases corresponds to the gas flow rate at 1.1 standard current density, and the pressures of the anode and cathode gases are 40 and 45 kPa respectively (the same gas supply pressure is used in the following stages, the same below). At the same time, the outlet temperature of the fuel cell coolant is controlled to be maintained at 63°C, and the load is reduced when the average voltage of the single cell is equal to 0.75V. Under the load of 0.04 standard current density, the control system sets the gas flow rate to 0.04 standard current density, then turns off the air supply to consume the residual oxygen remaining in the cathode. When the average voltage is 0.3V, the load current is turned off and the hydrogen supply is turned off.

[0069] After the stack was purged, the internal resistance of the stack was 1.1 times the wet state internal resistance after standing for 20 minutes, confirming that the stack purging failed.

[0070] Comparative Example 2

[0071] The only difference between this comparative example and Example 5 is that: 500 sections with an active area of ​​350 cm 2 The low-temperature purge steps of the fuel cell stack (water-cooled fuel cell stack, the same below) are as follows: the fuel cell is set to operate under the condition of 0.16 standard current density, during which dry, unheated hydrogen and air are respectively introduced into the anode and cathode of the battery. The flow rate of the anode and cathode gases corresponds to the gas flow rate at 1.1 standard current density, and the pressures of the anode and cathode gases are 40 and 45 kPa respectively (the same gas supply pressure is used in the following stages, the same below). At the same time, the outlet temperature of the fuel cell coolant is controlled to be maintained at 63°C, and the load is reduced when the average voltage of the single cell is equal to 0.75V. Under the load of 0.04 standard current density, the control system sets the gas flow rate to 0.04 standard current density, then turns off the air supply to consume the residual oxygen remaining in the cathode. When the average voltage is 0.3V, the load current is turned off and the hydrogen supply is turned off.

[0072] After the stack was purged, the internal resistance of the stack was 1.5 times the wet state internal resistance after standing for 20 minutes, confirming that the stack purging failed.

[0073] Comparative Example 3

[0074] The only difference between this comparative example and Example 3 is that the gas pressures at the anode and cathode are 25 kPa and 30 kPa, respectively.

[0075] After the stack was purged, the internal resistance of the stack was 1.3 times the wet state internal resistance after standing for 20 minutes, confirming that the stack purging failed.

[0076] Comparative Example 4

[0077] The only difference between this comparative example and Example 3 is that the pressures of the gases at the anode and cathode are 45 kPa and 50 kPa, respectively.

[0078] After the stack was purged, the internal resistance of the stack was 5.5 times the wet state internal resistance after standing for 20 minutes, confirming that the stack purging failed.

[0079] Comparative Example 5

[0080] The only difference between this comparative example and Example 9 is that the pressures of the gases at the anode and cathode are 45 kPa and 50 kPa, respectively.

[0081] After the stack was purged, the internal resistance of the stack was 5.8 times the wet state internal resistance after standing for 20 minutes, confirming that the stack purging failed.

[0082] Comparative Example 6

[0083] The only difference between this comparative example and Example 9 is that the gas pressures at the anode and cathode are 25 kPa and 30 kPa, respectively.

[0084] After the stack was purged, the internal resistance of the stack was 1.6 times the wet state internal resistance after standing for 20 minutes, confirming that the stack purging failed.

[0085] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

[0086] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A fuel cell low-temperature shutdown purge method, wherein after the following purge operation is completed, a judgment standard is used to determine whether the purge is successful. If so, the purge is terminated; otherwise, the purge operation is repeated. The judgment standard is as follows: after the purge is completed, the internal resistance value R1 of the fuel cell stack after standing for 10-30 minutes is obtained. When R1 ≥ the preset internal resistance value R0, the fuel cell stack purge is confirmed to be successful; otherwise, the stack purge is considered to have failed. The purge operation includes at least the following steps: Step (1), the fuel cell is operated at a standard current density of 0.15-0.18, dry hydrogen and dry air are introduced into the anode and cathode respectively, the gas flow rate corresponds to the gas flow rate at a standard current density of 1.2-1.4, the outlet temperature of the stack coolant is controlled to be maintained at 60-65°C, and the load is reduced when the average voltage of the cells is less than or equal to 0.7V; Step (2), when the load is reduced to 0.03-0.04 standard current density, the gas flow rate is set to 0.03-0.04 standard current density, and then the air supply is turned off. When the average voltage of the monomer drops to no more than V0, the load current is turned off and the hydrogen supply is turned off; Step (3), after the outlet temperature of the stack coolant drops to 5-20°C, resume gas supply, set the gas flow rate to a flow rate of 0.05-0.3 standard current density, and set the no-load purge time to 10-20 seconds; Step (4), reload to 0.03-0.04 standard current density, set the gas flow rate to 0.03-0.04 standard current density, then turn off the air supply, and when the average voltage of the monomer drops to no more than V0, turn off the load current and the hydrogen supply; Where V0 is 0.15-0.35V.

2. The fuel cell low-temperature shutdown purge method according to claim 1, characterized in that: The preset internal resistance value R0 is 2-5 times the wet state internal resistance r.

3. The fuel cell low-temperature shutdown purge method according to claim 1, characterized in that: In at least any one of steps (1) to (4): the pressure of the gas introduced into the anode is 30 kPa-40 kPa; and / or the pressure of the gas introduced into the cathode is 35 kPa-45 kPa.

4. The fuel cell low-temperature shutdown purge method according to claim 3, characterized in that: In steps (1) to (4): the pressure of the gas introduced into the anode remains unchanged; and / or the pressure of the gas introduced into the cathode remains unchanged.

5. The fuel cell low temperature shutdown purging method according to claim 1, 3 or 4, characterized in that: In steps (1) to (4): the gas introduced into the anode is preheated; and / or the gas introduced into the cathode is preheated.

6. The fuel cell low-temperature shutdown purge method according to claim 5, characterized in that: The preheating is to adjust the gas temperature to 5-65°C.

7. The fuel cell low-temperature shutdown purge method according to claim 5, characterized in that: In steps (1) to (4): the gas introduced into the anode is preheated and has a uniform temperature; and / or the gas introduced into the cathode is preheated and has a uniform temperature.

8. The fuel cell low temperature shutdown purge method according to claim 1, characterized in that: In step (2) and / or step (4): after the air supply is turned off, the time for the average voltage of the fuel cell to drop from the purge voltage to V0 is 5 to 20 seconds.

9. A purging device for implementing the fuel cell low-temperature shutdown purging method according to any one of claims 1 to 8.

10. A purge system comprising a carrying body and a plurality of purge devices according to claim 9 arranged on the carrying body.

11. A battery system comprising a plurality of battery stacks and a purge system according to claim 10 for purging the battery stacks before shutdown according to instructions.

12. A vehicle comprising a power system comprising the battery system according to claim 11.

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