Degradation protection system and method for fuel cell stack

Abstract

The invention discloses a degradation protection system and method for a fuel cell stack, and the system comprises a vacuum detection device which detects whether the anode or / and the cathode of the fuel cell stack are / is in vacuum after a fuel cell system is shut down; a hydrogen supply device in communication with the anode subsystem of the fuel cell stack, and in response to a vacuum occurrence signal detected by the vacuum detection device, increasing an anode internal pressure of the fuel cell stack to or below a fixed setpoint of an ambient pressure outside the stack, therefore, the hydrogen protection time is prolonged, and a hydrogen-air interface of the anode when the fuel cell system is started is prevented. Therefore, by adopting the system provided by the invention, the hydrogen protection time can be prolonged, the hydrogen-air interface of the anode during starting is avoided, and the degradation of the cathode catalyst and the substrate is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a degradation protection system and a protection method for a fuel cell stack. Background Art

[0002] If a fuel cell system is shut down for a long period of time (hours to days), air will eventually diffuse into the cathode and anode of the fuel cell. Over time, residual hydrogen from the previous shutdown is consumed and the fuel cell balances to a state where there is air at both the anode and cathode. It is well known that corrosion currents are generated when hydrogen is reintroduced into the system at startup. These corrosion currents degrade the cathode catalyst and substrate, causing performance loss with each cycle. The related art has the following defects: 1) Corrosion-resistant catalysts typically rely on a graphitized carbon matrix and a low catalyst surface area. These catalysts have better corrosion resistance, but have lower performance per gram of platinum. In addition, the corrosion rate is slowed down (not stopped), so additional methods are needed to ensure the service life of the product, especially in commercial applications. 2) Purging with inert gas is very effective in eliminating degradation problems, but requires storing and refilling the inert gas on the vehicle, which is difficult to achieve.

[0003] Therefore, it is necessary to develop a degradation protection system for a fuel cell stack. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one purpose of the present invention is to provide a degradation protection system and a protection method for a fuel cell stack. The protection system of the present application can increase the hydrogen protection time, avoid the hydrogen-air interface at the anode during startup, and reduce the degradation of the cathode catalyst and substrate.

[0005] In a first aspect of the present invention, the present invention provides a degradation protection system for a fuel cell stack. According to an embodiment of the present invention, the system comprises:

[0006] A vacuum detection device, which detects whether a vacuum occurs at the anode and / or cathode of the fuel cell stack after the fuel cell system is shut down;

[0007] A hydrogen supply device is connected to the anode subsystem of the fuel cell stack and increases the internal pressure of the anode of the fuel cell stack to the ambient pressure outside the stack or to a fixed set point lower than the ambient pressure outside the stack in response to a vacuum occurrence signal detected by a vacuum detection device, thereby extending the hydrogen protection time and preventing the occurrence of a hydrogen-air interface at the anode when the fuel cell system is started.

[0008] A degradation protection system for a fuel cell stack according to an embodiment of the present invention includes a vacuum detection device and a hydrogen supply device, wherein the vacuum detection device detects whether a vacuum occurs at the anode and / or cathode of the fuel cell stack after the fuel cell system is shut down, that is, when the vacuum detection device detects that the pressure at the anode and / or cathode of the fuel cell system is less than the ambient pressure outside the stack, the vacuum detection device generates a vacuum occurrence signal, and the hydrogen supply device is connected to the anode subsystem of the fuel cell stack, and is capable of responding to the above-mentioned vacuum occurrence signal, immediately supplying hydrogen to the anode, and increasing the internal pressure of the anode of the fuel cell stack to the ambient pressure outside the stack or to a fixed set point lower than the ambient pressure outside the stack, thereby extending the hydrogen protection time, avoiding the occurrence of a hydrogen-air interface at the anode during startup, and reducing the degradation of the cathode catalyst and substrate without the need for a corrosion-resistant catalyst or inert gas purging.

[0009] In addition, the degradation protection system for a fuel cell stack according to the above embodiment of the present invention may also have the following additional technical features:

[0010] In some embodiments of the present invention, the vacuum detection device includes a pressure sensor, and the pressure sensor is used to detect the internal pressure of the anode and / or cathode of the fuel cell stack.

[0011] In some implementations of the present invention, the hydrogen supply device includes a hydrogen storage tank in communication with the anode subsystem of the fuel cell stack.

[0012] In some embodiments of the present invention, the hydrogen supply device further includes a control valve, and the control valve is used to adjust the flow of hydrogen from the hydrogen storage tank to the anode subsystem of the fuel cell stack.

[0013] In some embodiments of the present invention, the hydrogen supply device further includes a pressure regulator, and the pressure regulator is used to adjust the pressure of hydrogen supplied to the anode subsystem of the fuel cell stack.

[0014] In some embodiments of the present invention, the hydrogen supply device further includes a hydrogen injection mechanism, which is used to introduce hydrogen into the anode subsystem of the fuel cell stack.

[0015] In some embodiments of the present invention, a control unit is further included, which receives a vacuum occurrence signal from the vacuum detection device and controls the hydrogen supply device to increase the internal pressure of the anode of the fuel cell stack to the ambient pressure outside the stack or a fixed set point lower than the ambient pressure outside the stack based on the detected vacuum occurrence signal.

[0016] In some embodiments of the present invention, the hydrogen supply device is connected to a fuel cell vehicle to supply hydrogen to the anode subsystem of the fuel cell stack when the vehicle is shut down.

[0017] In a second aspect of the present invention, a method for extending the hydrogen protection time of a fuel cell stack is provided. According to an embodiment of the present invention, the method comprises: a) detecting whether a vacuum occurs at the anode or / and cathode of the fuel cell stack after the fuel cell system is shut down; b) increasing the internal pressure of the anode of the fuel cell stack to the ambient pressure outside the stack or a fixed set point lower than the ambient pressure outside the stack based on the detected vacuum occurrence signal.

[0018] According to the method for extending the hydrogen protection time of a fuel cell stack in an embodiment of the present invention, by detecting whether a vacuum occurs at the anode and / or cathode of the fuel cell stack after the fuel cell system is shut down, that is, when it is detected that the pressure of the anode and / or the cathode is less than the ambient pressure outside the stack, the internal pressure of the anode of the fuel cell stack is increased to the ambient pressure outside the stack or to a fixed set point lower than the ambient pressure outside the stack, thereby extending the hydrogen protection time and avoiding the occurrence of a hydrogen-air interface at the anode during startup, and reducing the degradation of the cathode catalyst and substrate without the need for a corrosion-resistant catalyst or inert gas purging.

[0019] In addition, the method for extending the hydrogen protection time of a fuel cell stack according to the above embodiment of the present invention may also have the following additional technical features:

[0020] In some embodiments of the present invention, increasing the internal pressure of the anode includes supplying hydrogen gas to an anode subsystem of the fuel cell stack.

[0021] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 is a schematic structural diagram of a degradation protection system for a fuel cell stack according to an embodiment of the present invention;

[0024] Figure 2 The figure is a flow chart of a method for extending the hydrogen protection time of a fuel cell stack according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0027] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The present invention is based on the following discovery of the inventors: after the fuel cell system is shut down, if there is residual hydrogen and oxygen in the stack, auxiliary components and pipelines, due to the existence of concentration gradient, the oxygen on the cathode side can penetrate to the anode side through the proton exchange membrane, or the oxygen in the environment can slowly penetrate to the anode side through the sealing ring, forming a hydrogen / air interface on the anode side. At this time, one side of the membrane electrode is full of air, and the other side has both air and hydrogen, so a high potential will be generated, causing serious corrosion to the carbon carrier. The corrosion damage of the hydrogen-air interface is mainly on the cathode side. After the carbon carrier is corroded, platinum will fall off, the three-phase interface will be damaged, and finally the performance of the fuel cell will seriously decline. Its severity far exceeds the life decay caused by high potential in the actual operation of the fuel cell.

[0029] In a first aspect of the present invention, the present invention provides a degradation protection system for a fuel cell stack. Figure 1 The above-mentioned degradation protection system for the fuel cell stack includes: a vacuum detection device 100 and a hydrogen supply device 200. The vacuum detection device 100 detects whether a vacuum occurs in the anode 300 and / or the cathode 400 of the fuel cell stack 1 after the fuel cell system is shut down. Specifically, the vacuum detection device 100 can be set at the anode 300, or at the cathode 400, or at both the anode 300 and the cathode 400. Figure 1Only the case where the vacuum detection device 100 is arranged at the anode 300 is shown. When the vacuum detection device 100 detects that the pressure of the anode 300 and / or cathode 400 of the fuel cell system is less than the ambient pressure outside the stack, the vacuum detection device 100 will generate a vacuum occurrence signal. The hydrogen supply device 200 is connected to the anode subsystem of the fuel cell stack 1, and can respond to the above vacuum occurrence signal, immediately supply hydrogen to the anode 300, and increase the internal pressure of the anode 300 of the fuel cell stack 1 to the ambient pressure outside the stack or a fixed set point lower than the ambient pressure outside the stack, thereby extending the hydrogen protection time, avoiding the hydrogen-air interface at the anode during startup, and reducing the degradation of the cathode catalyst and substrate without the need for a corrosion-resistant catalyst or inert gas purge.

[0030] Furthermore, the vacuum detection device 100 includes a pressure sensor (not shown), which can be used to detect the internal pressure of the anode and / or cathode of the fuel cell stack. When the pressure sensor detects that the pressure of the anode 300 and / or cathode 400 of the fuel cell system is less than the external environment pressure of the stack, the pressure sensor will generate a vacuum occurrence signal. It should be noted that those skilled in the art can select the specific type of pressure sensor according to actual needs, as long as the above functions can be achieved.

[0031] Furthermore, the hydrogen supply device 200 includes a hydrogen storage tank 21 connected to the anode subsystem of the fuel cell stack. Thus, the hydrogen storage tank can provide a source of hydrogen. It should be noted that those skilled in the art can select the specific type of hydrogen storage tank according to actual needs, as long as the above functions can be achieved.

[0032] Furthermore, the hydrogen supply device 200 further includes a control valve 22, which is disposed between the hydrogen storage tank 21 and the inlet of the anode 300, and is used to adjust the hydrogen flow from the hydrogen storage tank to the anode subsystem of the fuel cell stack. It should be noted that those skilled in the art can select the specific type of the control valve according to actual needs, as long as the above functions can be achieved.

[0033] Furthermore, the hydrogen supply device 200 further includes a pressure regulator (not shown), which is disposed between the hydrogen storage tank 21 and the inlet of the anode 300, and is used to adjust the hydrogen pressure supplied to the anode subsystem of the fuel cell stack. It should be noted that those skilled in the art can select the specific type of the pressure regulator according to actual needs, as long as the above functions can be achieved.

[0034] Furthermore, the hydrogen supply device 200 also includes a hydrogen injection mechanism 23, one end of the hydrogen injection mechanism 23 is connected to the hydrogen storage tank 21, and the other end is connected to the inlet of the anode 300. The hydrogen injection mechanism 23 is used to introduce hydrogen into the anode subsystem of the fuel cell stack.

[0035] Furthermore, the above-mentioned degradation protection system for the fuel cell stack also includes a control unit 500, which is respectively connected to the vacuum detection device 100 and the hydrogen supply device 200. The control unit 500 receives a vacuum occurrence signal from the vacuum detection device 100, and controls the hydrogen supply device 200 based on the detected vacuum occurrence signal to increase the internal pressure of the anode of the fuel cell stack to the ambient pressure outside the stack or a fixed set point lower than the ambient pressure outside the stack.

[0036] Furthermore, the fuel cell system also includes a fuel recycling device 600, the outlet end of the fuel recycling device 600 is connected to the inlet of the anode 300, and the inlet end of the fuel recycling device 600 is connected to the outlet of the anode. Thus, the unreacted hydrogen of the stack can be recycled to the hydrogen inlet of the stack, thereby improving the utilization rate of hydrogen and hydrogen-related safety. At the same time, the water generated by the electrochemical reaction inside the stack can also be circulated to the inlet of the fuel cell stack to improve the moisture level of the stack. It should be noted that those skilled in the art can select the specific type of the fuel recycling device 600 according to actual needs, as long as the above functions can be achieved.

[0037] Furthermore, a check valve 61 is provided between the outlet end of the fuel recirculation device 600 and the inlet of the anode 300. Thus, gas backflow can be prevented. It should be noted that those skilled in the art can select the specific type of the check valve according to actual needs, as long as the above functions can be achieved.

[0038] Furthermore, the fuel cell stack 1 is provided with a coolant inlet (not shown) and a coolant outlet (not shown), the coolant inlet is provided with a coolant inlet pipeline (not shown) that can be connected to the coolant supply system (not shown), and the coolant outlet is provided with a coolant outlet pipeline (not shown). Thus, it can be ensured that the fuel cell system operates within a suitable temperature range to ensure a high power supply efficiency. It should be noted that the specific positions of the coolant inlet and the coolant outlet belong to the conventional technology in this field, and those skilled in the art can select the specific type of the coolant supply system according to actual needs, as long as the above functions can be achieved.

[0039] Furthermore, the hydrogen supply device 200 is connected to the fuel cell vehicle to supply hydrogen to the anode subsystem of the fuel cell stack when the vehicle is shut down.

[0040] The degradation protection system for a fuel cell stack of the present application includes a vacuum detection device, a hydrogen supply device and a control unit. The pressure sensor in the vacuum detection device detects whether a vacuum occurs in the anode or / and cathode of the fuel cell stack after the fuel cell system is shut down and generates a vacuum occurrence signal. The control unit receives the vacuum occurrence signal from the vacuum detection device, and controls the hydrogen storage tank to supply hydrogen to the anode subsystem through the hydrogen injection mechanism based on the detected vacuum occurrence signal, and controls the pressure regulator and the control valve to adjust the hydrogen pressure and hydrogen flow rate supplied to the anode subsystem of the fuel cell stack respectively, so that the internal pressure of the anode of the fuel cell stack increases to the ambient pressure outside the stack or a fixed set point lower than the ambient pressure outside the stack, thereby extending the hydrogen protection time, avoiding the appearance of a hydrogen-air interface at the anode during startup, and reducing the degradation of the cathode catalyst and substrate without the use of a corrosion-resistant catalyst or an inert gas purge. At the same time, the system also includes a fuel recycling device, the outlet end of the fuel recycling device is connected to the inlet of the anode, the inlet end of the fuel recycling device is connected to the outlet of the anode, and a check valve is provided between the outlet end and the inlet of the anode to prevent gas backflow, and the fuel recycling device can improve the utilization rate of hydrogen and the hydration degree of the stack. In addition, the fuel cell stack is provided with a coolant inlet and a coolant outlet. The coolant inlet is provided with a coolant inlet pipeline that can be connected to the coolant supply system, and the coolant outlet is provided with a coolant outlet pipeline. Thus, the fuel cell system can be ensured to operate within an appropriate temperature range to ensure a high power supply efficiency.

[0041] In a second aspect of the present invention, the present invention provides a method for extending the hydrogen protection time of a fuel cell stack. Figure 2 , the above method comprises:

[0042] Sa: Detect whether there is vacuum at the anode and / or cathode of the fuel cell stack after the fuel cell system is shut down

[0043] In this step, it is detected whether a vacuum occurs at the anode of the fuel cell stack after the fuel cell system is shut down, or whether a vacuum occurs at the cathode of the fuel cell stack after the fuel cell system is shut down, or whether a vacuum occurs at the anode and cathode of the fuel cell stack after the fuel cell system is shut down. Specifically, the occurrence of a vacuum refers to the detection that the pressure of the anode and / or cathode of the fuel cell system is less than the ambient pressure outside the stack. Specifically, the above-mentioned vacuum detection device can be used to detect whether a vacuum occurs at the anode of the fuel cell stack after the fuel cell system is shut down. When the vacuum detection device detects that a vacuum occurs at the anode and / or cathode, a vacuum occurrence signal is generated. The above-mentioned vacuum detection device includes a pressure sensor, which is used to detect the internal pressure of the anode and / or cathode of the fuel cell stack.

[0044] Sb: Based on the detected vacuum signal, the internal pressure of the anode of the fuel cell stack is increased to the ambient pressure outside the stack or a fixed set point below the ambient pressure outside the stack.

[0045] In this step, based on the detected vacuum signal, the internal pressure of the anode of the fuel cell stack is increased to the ambient pressure outside the stack or a fixed set point lower than the ambient pressure outside the stack, thereby extending the hydrogen protection time and avoiding the appearance of a hydrogen-air interface at the anode during startup. The degradation of the cathode catalyst and substrate can be reduced without the use of a corrosion-resistant catalyst or inert gas purge.

[0046] Further, increasing the internal pressure of the anode includes supplying hydrogen to the anode subsystem of the fuel cell stack. For example, the above-mentioned hydrogen supply device can be used to supply hydrogen to the anode subsystem of the fuel cell stack. The specific type of the hydrogen supply device is the same as described above and will not be repeated here. The hydrogen supply device is connected to the anode subsystem of the fuel cell stack and can respond to the above-mentioned vacuum occurrence signal to immediately supply hydrogen to the anode, increase the internal pressure of the anode of the fuel cell stack to the ambient pressure outside the stack or a fixed set point below the ambient pressure outside the stack, thereby extending the hydrogen protection time, avoiding the appearance of a hydrogen-air interface at the anode during startup, and reducing the degradation of the cathode catalyst and substrate without the need for a corrosion-resistant catalyst or an inert gas purge.

[0047] The inventors have discovered that by detecting whether a vacuum appears at the anode and / or cathode of the fuel cell stack after the fuel cell system is shut down, that is, when it is detected that the pressure of the anode and / or the cathode is less than the ambient pressure outside the stack, the internal pressure of the anode of the fuel cell stack is increased to the ambient pressure outside the stack or to a fixed set point that is lower than the ambient pressure outside the stack, thereby extending the hydrogen protection time and avoiding the appearance of a hydrogen-air interface at the anode during startup, and reducing the degradation of the cathode catalyst and substrate without the need for a corrosion-resistant catalyst or inert gas purging.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0049] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A degradation protection system for a fuel cell stack, characterized in that: include: A vacuum detection device, which detects whether a vacuum occurs at the anode and / or cathode of the fuel cell stack after the fuel cell system is shut down; A hydrogen supply device is connected to the anode subsystem of the fuel cell stack and increases the internal pressure of the anode of the fuel cell stack to the ambient pressure outside the stack or to a fixed set point lower than the ambient pressure outside the stack in response to a vacuum occurrence signal detected by a vacuum detection device, thereby extending the hydrogen protection time and preventing the occurrence of a hydrogen-air interface at the anode when the fuel cell system is started.

2. The system according to claim 1, characterized in that The vacuum detection device includes a pressure sensor, and the pressure sensor is used to detect the internal pressure of the anode and / or cathode of the fuel cell stack.

3. The system according to claim 1, characterized in that The hydrogen supply device includes a hydrogen storage tank in communication with an anode subsystem of the fuel cell stack.

4. The system according to claim 3, characterized in that The hydrogen supply device further includes a control valve for regulating a flow rate of hydrogen from the hydrogen storage tank to the anode subsystem of the fuel cell stack.

5. The system according to any one of claims 1 to 4, characterized in that: The hydrogen supply device further includes a pressure regulator, which is used to adjust the pressure of hydrogen supplied to the anode subsystem of the fuel cell stack.

6. The system according to claim 5, characterized in that The hydrogen supply device further comprises a hydrogen injection mechanism, which is used to introduce hydrogen into the anode subsystem of the fuel cell stack.

7. The system according to any one of claims 1 to 4, characterized in that: The invention also includes a control unit, which receives a vacuum occurrence signal from the vacuum detection device and controls the hydrogen supply device to increase the internal pressure of the anode of the fuel cell stack to the ambient pressure outside the stack or a fixed set point lower than the ambient pressure outside the stack based on the detected vacuum occurrence signal.

8. The system according to any one of claims 1 to 4, characterized in that: The hydrogen supply device is connected to the fuel cell vehicle and supplies hydrogen to the anode subsystem of the fuel cell stack when the vehicle is turned off.

9. A method for extending the hydrogen protection time of a fuel cell stack, characterized in that: include: a) Detecting whether a vacuum occurs at the anode and / or cathode of the fuel cell stack after the fuel cell system is shut down; b) Based on the detected vacuum occurrence signal, the internal pressure of the anode of the fuel cell stack is increased to the ambient pressure outside the stack or a fixed set point lower than the ambient pressure outside the stack.

10. The method according to claim 9, characterized in that Increasing the internal pressure of the anode includes supplying hydrogen gas to an anode subsystem of the fuel cell stack.

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