Method and system for managing a fuel cell stack

Abstract

The invention relates to a method and system for managing a fuel cell stack. A fuel cell system and associated method of operation, the method of operation comprising: assembling a fuel cell stack, the fuel cell stack comprising an exhaust valve; flowing a premixed gas containing carbon monoxide through the fuel cell stack; and closing the discharge valve, including prior to storage. Subsequently, the exhaust valve may be opened, and a refresh operation may be performed to purge carbon monoxide from the fuel cell stack.

Description

Technical Field

[0001] introduction

[0002] The present disclosure relates to a fuel cell system including a fuel cell stack having a platinum catalyst layer. Background Art

[0003] A fuel cell is an electrochemical device consisting of a plurality of anode electrodes receiving hydrogen (H2), a plurality of cathode electrodes receiving oxygen (O2), and a plurality of electrolytes or an electrolyte solution interposed between each anode and cathode. An electrochemical reaction is induced to oxidize hydrogen molecules at the anode to generate protons (H+), which then pass through the electrolyte to be reduced at the cathode using an oxidant (such as oxygen). The reaction generates electrons at the anode, some of which are redirected by a load (such as a traction motor of a vehicle or a non-vehicle load requiring fixed power generation) and then sent to the cathode. Such a fuel cell can be used in combination with other fuel cells to form a fuel cell stack. Such a stack of fuel cells or a fuel cell stack can be electrically connected to each other (e.g., in series) so that the voltage supplied by each fuel cell is added to the next fuel cell, so that the total voltage supplied by the fuel cell stack is the sum of the voltages of each of the stacked fuel cells.

[0004] Electrified drivetrains (e.g., hybrid electric and all-electric systems) can utilize fuel cell systems to power one or more electric traction motors. One factor that determines the commercial viability of fuel cells is their durability. Fuel cells for motor vehicles equipped with electric drive powertrains may be tasked with providing at least 30,000 hours of service. Such high durability requirements may pose challenges to one or more components of the fuel cell.

[0005] Fuel cells can use platinum nanoparticles supported on carbon black particles. Over a period of time, the carbon black particles can be oxidized to CO2 in the presence of a Pt catalyst, an acidic electrolyte, and O2. For known fuel cell systems, in order to prepare for long-term storage, it is known to purge the fuel cell stack with hydrogen to protect the electrodes from the influence of oxygen in the ambient air. However, ambient air can penetrate into the fuel cell stack through the air inlet, tail pipe, or seal. The invading oxygen causes carbon corrosion in two main ways. Carbon corrosion may occur due to slow oxidation of carbon black when stored in an oxygen environment. Carbon corrosion may occur when both hydrogen and oxygen are present on the same side of the channel. In this case, hydrogen may become a fuel to rapidly oxidize carbon black, which may cause a corrosion reaction of carbon black particles driven by hydrogen. Summary of the invention

[0006] For a fuel cell system having a fuel cell stack that employs carbon black particles as a carrier for platinum nanoparticles, it is desirable to provide a method and system to minimize or eliminate the risk of oxidation of the carbon black particles contained therein during extended periods of inactivity (e.g., during transportation or long-term storage of the fuel cell stack).

[0007] Aspects of the present disclosure may include a method for operating a fuel cell system, the method comprising: assembling a fuel cell stack including a bleed valve; flowing a premixed gas including carbon monoxide through the fuel cell stack; and closing the bleed valve.

[0008] Another aspect of the present disclosure may include: opening a purge valve; and performing a refresh operation to purge carbon monoxide from the fuel cell stack.

[0009] Another aspect of the present disclosure may include performing a refresh operation to purge carbon monoxide from the fuel cell stack by flowing ambient air through the fuel cell stack.

[0010] Another aspect of the present disclosure may include a fuel cell stack including an anode and a cathode, wherein performing a refresh operation to purge carbon monoxide from the fuel cell stack includes flowing ambient air through the cathode.

[0011] Another aspect of the present disclosure may include flowing a premixed gas containing carbon monoxide through a fuel cell stack by flowing the premixed gas containing carbon monoxide and hydrogen through the fuel cell stack.

[0012] Another aspect of the present disclosure may include flowing a premixed gas containing hydrogen (H 2 ) and carbon monoxide (CO) at a ratio of 99.95% H 2 to 0.05% CO.

[0013] Another aspect of the present disclosure may include flowing a premixed gas containing carbon monoxide and nitrogen.

[0014] Another aspect of the present disclosure may include flowing a premixed gas containing carbon monoxide and argon.

[0015] Another aspect of the present disclosure may include flowing a premixed gas containing carbon monoxide and helium.

[0016] Another aspect of the present disclosure may include flowing a premixed gas containing at least a 0.01% concentration of CO through a fuel cell stack.

[0017] Another aspect of the present disclosure may include a method for operating a fuel cell stack, the method comprising: flowing a gas containing carbon monoxide through the fuel cell stack for a predetermined period of time; and then, sealing the fuel cell stack from air intrusion.

[0018] Another aspect of the present disclosure may include a fuel cell system having a fuel cell stack including an anode and a cathode separated by a fuel cell membrane. The anode has a first catalyst layer, a first microporous layer, a first gas diffusion layer, and a first bipolar plate, and the cathode has a second catalyst layer, a second microporous layer, a second gas diffusion layer, and a second bipolar plate. The second catalyst layer includes a carbon support and platinum-based catalyst nanoparticles dispersed on the carbon support, wherein the carbon support of the second catalyst layer of the fuel cell stack is protected from corrosion by forcing carbon monoxide gas on the first catalyst layer during storage.

[0019] The present disclosure also provides the following technical solutions:

[0020] 1. A method for operating a fuel cell system, the method comprising:

[0021] assembling a fuel cell stack, the fuel cell stack including a bleed valve and an isolation valve;

[0022] flowing a premixed gas containing carbon monoxide through the fuel cell stack; and

[0023] Close the discharge valve and the isolation valve.

[0024] 2. The method according to technical solution 1 further comprises:

[0025] opening the discharge valve and the isolation valve; and

[0026] A flushing operation is performed to purge the carbon monoxide from the fuel cell stack.

[0027] 3. The method according to technical solution 2, wherein performing the refresh operation to purge the carbon monoxide from the fuel cell stack includes: allowing ambient air to flow through the fuel cell stack.

[0028] 4. The method according to technical solution 2, wherein the fuel cell stack comprises an anode and a cathode; and

[0029] Wherein, performing the refresh operation to purge the carbon monoxide from the fuel cell stack includes: flowing ambient air through the cathode.

[0030] 5. The method according to Technical Solution 1, wherein causing the premixed gas containing carbon monoxide to flow through the fuel cell stack comprises: causing the premixed gas containing carbon monoxide and hydrogen to flow through the fuel cell stack.

[0031] 6. The method according to technical solution 5, wherein causing the premixed gas containing carbon monoxide and hydrogen to flow includes causing the premixed gas containing hydrogen (H2) and carbon monoxide (CO) to flow at a ratio of 99.9% H2 to 0.1% CO.

[0032] 7. The method according to Technical Solution 1, wherein causing the premixed gas containing carbon monoxide to flow through the fuel cell stack comprises: causing the premixed gas containing carbon monoxide and nitrogen to flow.

[0033] 8. The method according to Technical Solution 1, wherein causing the premixed gas containing carbon monoxide to flow through the fuel cell stack comprises: causing a premixed gas containing carbon monoxide and argon to flow.

[0034] 9. The method according to Technical Solution 1, wherein causing the premixed gas containing carbon monoxide to flow through the fuel cell stack comprises: causing the premixed gas containing carbon monoxide and helium to flow.

[0035] 10. The method according to technical solution 1, wherein causing the premixed gas containing carbon monoxide to flow through the fuel cell stack comprises: causing the premixed gas containing at least 0.1% CO concentration to flow through the fuel cell stack.

[0036] 11. A method for operating a fuel cell stack, the method comprising:

[0037] flowing a gas containing carbon monoxide through the fuel cell stack for a predetermined period of time; and

[0038] The fuel cell stack is sealed against air intrusion via a bleed valve and an isolation valve.

[0039] 12. The method according to technical solution 11 further includes: performing a refresh operation to purge the carbon monoxide from the fuel cell stack.

[0040] 13. A method according to technical solution 12, wherein performing the refresh operation to purge the carbon monoxide from the fuel cell stack comprises: opening the exhaust valve and the isolation valve; and allowing ambient air to flow through the fuel cell stack.

[0041] 14. The method according to technical solution 12, wherein the fuel cell stack comprises an anode and a cathode; and

[0042] Wherein, performing the refresh operation to purge the carbon monoxide from the fuel cell stack includes: flowing ambient air through the cathode.

[0043] 15. A method according to technical solution 11, wherein causing the gas containing carbon monoxide to flow through the fuel cell stack comprises: causing a premixed gas containing carbon monoxide and hydrogen to flow through the fuel cell stack.

[0044] 16. A method according to technical solution 15, wherein causing the gas containing carbon monoxide and hydrogen to flow comprises causing the premixed gas containing hydrogen (H2) and carbon monoxide (CO) to flow at a ratio of 99.95% H2 to 0.05% CO.

[0045] 17. A method according to technical solution 11, wherein causing the gas containing carbon monoxide to flow through the fuel cell stack includes: causing a premixed gas containing carbon monoxide and nitrogen to flow.

[0046] 18. A method according to technical solution 11, wherein causing the gas containing carbon monoxide to flow through the fuel cell stack includes: causing a premixed gas containing carbon monoxide and argon to flow.

[0047] 19. A method according to technical solution 11, wherein allowing the gas containing carbon monoxide to flow through the fuel cell stack includes: allowing a premixed gas containing 10 ppm (parts per million) of CO to flow through the fuel cell stack.

[0048] 20. A fuel cell system comprising:

[0049] a fuel cell stack comprising an anode and a cathode separated by a fuel cell membrane;

[0050] The anode has a first catalyst layer, a first microporous layer, a first gas diffusion layer and a first bipolar plate;

[0051] The cathode has a second catalyst layer, a second microporous layer, a second gas diffusion layer, and a second bipolar plate; and

[0052] The second catalyst layer includes a carbon support and platinum-based catalyst nanoparticles dispersed on the carbon support;

[0053] Therein, the carbon support of the second catalyst layer of the fuel cell stack is protected from corrosion during storage by forcing carbon monoxide gas onto the second catalyst layer.

[0054] The above summary is not intended to represent every possible embodiment or every aspect of the present disclosure. On the contrary, the foregoing summary is intended to illustrate some of the novel aspects and features disclosed herein. The above features and advantages of the present disclosure and other features and advantages will be readily apparent from the following detailed description of representative embodiments and modes for implementing the present disclosure when taken in conjunction with the accompanying drawings and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] One or more embodiments will now be described by way of example with reference to the accompanying drawings, in which:

[0056] Figure 1 A fuel cell system including a fuel cell stack according to the present disclosure is schematically illustrated.

[0057] Figure 2 A process for a fuel cell stack for a fuel cell system according to the present disclosure is schematically illustrated.

[0058] The accompanying drawings are not necessarily drawn to scale and may present somewhat simplified representations of various preferred features of the present disclosure as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes. The details associated with such features will be determined in part by the specific intended application and use environment. DETAILED DESCRIPTION

[0059] As described and illustrated herein, the components of the disclosed embodiments may be arranged and designed in various configurations. Therefore, the following detailed description is not intended to limit the scope of the present disclosure as claimed, but is merely representative of possible embodiments thereof. In addition, although numerous specific details are set forth in the following description in order to provide a thorough understanding of the embodiments disclosed herein, some embodiments may be practiced without some of these details. In addition, for the purpose of clarity, certain technical materials understood in the related art are not described in detail in order to avoid unnecessarily obscuring the present disclosure.

[0060] For the purpose of convenience and clarity, directional terms such as top, bottom, left, right, upward, above, above, below, below, rear, and front may be used with respect to the drawings. These and similar directional terms are not to be construed as limiting the scope of the present disclosure. In addition, as illustrated and described herein, the present disclosure may be practiced without elements not specifically disclosed herein.

[0061] The following detailed description is merely illustrative in nature and is not intended to limit application and use. In addition, it is not intended to be bound by any explicit or implicit theory presented herein. Throughout the drawings, corresponding reference numerals indicate similar or corresponding parts and features.

[0062] As used herein, the term "system" may refer to one or a combination of mechanical and electrical actuators, sensors, controllers, application specific integrated circuits (ASICs), combinatorial logic circuits, software, firmware, and / or other components arranged to provide the described functionality.

[0063] As employed herein, the term "upstream" and related terms refer to elements toward the origin of the flow relative to the indicated location, and the term "downstream" and related terms refer to elements away from the origin of the flow relative to the indicated location.

[0064] The use of ordinal numbers such as first, second, and third does not necessarily imply a sense of sequential order, but rather may distinguish multiple instances of an action or structure.

[0065] The embodiments may be described herein in terms of functional and / or logical block components and various processing steps or operations. Such block components may be implemented by a combination or collection of mechanical and electrical hardware, software and / or firmware components configured to perform the specified functions.

[0066] Detailed embodiments related to the present disclosure are disclosed herein. It should be understood that the disclosed embodiments are merely illustrative of the present disclosure, and these embodiments may be embodied in various and alternative forms. The specific structural and functional details disclosed herein are not to be construed as limiting, but merely as a representative basis for teaching those skilled in the art to adopt the present disclosure in various ways.

[0067] The numerical values ​​of all parameters (e.g., quantities or conditions) in this specification (including the appended claims) will be understood to be modified by the term "approximately" in all cases, regardless of whether "approximately" actually appears before the numerical value. "Approximately" indicates that the stated numerical value allows for slight imprecision (some approach to precision in the value; approximately or reasonably close to the value; approximately). If the imprecision provided by "approximately" is not understood in this ordinary sense in the art, "approximately" as used herein at least indicates the variation that may arise from the ordinary methods of measuring and using such parameters. In addition, the disclosure of the range includes the disclosure of all values ​​within the entire range and the further divided ranges. Each value within the range and the endpoints of the range are hereby all disclosed as separate embodiments.

[0068] The present disclosure relates to a fuel cell system having a fuel cell stack including an anode and a cathode separated by a fuel cell membrane. The anode has a first catalyst layer, a first microporous layer, a first gas diffusion layer, and a first bipolar plate, and the cathode has a second catalyst layer, a second microporous layer, a second gas diffusion layer, and a second bipolar plate. The second catalyst layer includes a carbon support and platinum-based catalyst nanoparticles dispersed on the carbon support, wherein the carbon support of the second catalyst layer of the fuel cell stack is protected from corrosion by forcing carbon monoxide gas on the first catalyst layer and the second catalyst layer during storage.

[0069] Referring now to the drawings, wherein like reference numerals refer to like elements, a fuel cell system is shown and described herein. Figure 1is a schematic perspective view of a fuel cell system 10 according to an embodiment of the present disclosure. As illustrated, the fuel cell system 10 includes a fuel cell stack 50, a hydrogen storage tank 20, a fuel injector 32, and a fuel injector 34, both of which supply a hydrogen flow to an ejector device 30. For simplicity, the fuel cell stack 50 is illustrated as a single fuel cell, which includes an anode 52 and a cathode 54 separated by a fuel cell membrane 56 (or a polymer electrolyte membrane (PEM)). However, it will be understood that the fuel cell system 10 may include a plurality of fuel cell stacks 50, the plurality of fuel cell stacks including a plurality of pairs of anodes 52 and cathodes 54.

[0070] As viewed in the figures, a fuel cell membrane or PEM 56 is sandwiched or otherwise disposed between an anode 52 and a cathode 54. Proceeding outwardly from the PEM 56, the anode 52 includes a catalyst layer 36 (or anode substrate), a microporous layer 38, a gas diffusion layer 40, and a bipolar plate 42. Similarly, proceeding outwardly from the PEM 56, the cathode 54 includes a catalyst layer 44 (or cathode substrate), a microporous layer 45, a gas diffusion layer 46, and a bipolar plate 48.

[0071] An anode gas loop 70 including a hydrogen flow is provided to the anode 52. A cathode gas subsystem 60 including a compressed air flow is provided to the cathode 54. As described herein, the fuel cell stack 50 utilizes the hydrogen flow at the anode 52 and the compressed air at the cathode 54 to generate electrical energy for use by a vehicle or system equipped with the fuel cell stack 50.

[0072] Hydrogen is supplied at high pressure from a hydrogen storage tank 20. A shutoff valve 22 is provided and is capable of selectively permitting or disallowing hydrogen to flow from the hydrogen storage tank 20 to the rest of the fuel cell system 10. A pressure regulator 24 is provided that controls and steps down the pressure of the hydrogen from the high pressure delivered by the hydrogen storage tank 20 to a medium pressure for delivery to the fuel injector 32 and the fuel injector 34. A pressure sensor 26 is provided between the pressure sensor 24 and the two fuel injectors 32, 34.

[0073] The fuel injectors 32 and 34 are operable to selectively open and supply hydrogen to the anode gas loop 70, and selectively close and prohibit hydrogen from flowing into the anode gas loop 70. Hydrogen is delivered to the fuel injectors 32 and 34 at a medium pressure. The fuel injectors 32 and 34 supply hydrogen to the anode gas loop 70 at a low pressure by cycling between an open state and a closed state: opening to increase the pressure to a maximum desired anode gas loop pressure; closing when the pressure within the anode gas loop 70 reaches the maximum desired anode gas loop pressure; and opening again when the pressure within the anode gas loop 70 reaches the minimum desired anode gas loop pressure. The fuel injectors 32 and 34 may be used to maintain the pressure within the anode gas loop 70 within a desired low pressure range by opening the fuel injectors 32 and the fuel injectors 34 when the pressure within the anode gas loop 70 reaches a minimum desired anode gas loop pressure, and closing the fuel injectors 32 and the fuel injectors 34 when the pressure within the anode gas loop 70 reaches a maximum desired anode gas loop pressure.

[0074] The ejector device 30 is a device useful for providing hydrogen from the fuel injector 32 and the fuel injector 34 to the anode gas loop 70. The ejector device 30 includes a venturi configuration. The hydrogen flowing through the ejector device 30 flows over the venturi tube within the ejector device 30. The anode gas loop 70 includes an upstream portion 72 upstream of the anode 52 and a downstream portion 74 downstream of the anode 52. The upstream portion 72 includes a high concentration of hydrogen. When the hydrogen passes through the anode 52, a considerable portion of the hydrogen can be consumed by the anode 52. However, a lower concentration of hydrogen can remain in the downstream portion 74. The downstream portion 74 is connected to the venturi tube of the ejector device 30 so that the hydrogen moves from the fuel injector 32 and the fuel injector 34 through the ejector device 30 and enters the upstream portion 72, thereby flowing over the venturi device and drawing the gas from the downstream portion 74 into the gas flowing into the upstream portion 72. In this way, gas from the downstream portion 74 is recirculated through the anode 52. A pressure sensor 76 is provided to monitor the pressure within the upstream portion 72.

[0075] Water (as a byproduct of the chemical reactions of the fuel cell stack 50) may exit the anode 52. The downstream portion 74 may include an anode water separator and an anode drain valve useful for draining water from the downstream portion 74.

[0076] Air is provided to the cathode 54, thereby supplying oxygen for the fuel cell stack reaction. An air compressor 66 is provided for inhaling ambient air and providing a pressurized air flow through the cathode gas subsystem 60. The flow through the air compressor 66 is controlled via an isolation valve 65, which is a flow control valve that can be controlled to manage the air flow to the fuel cell stack 50, including being controllable to block the air flow between the fuel cell stack 50 and the atmosphere 77 via a conduit 67. In one embodiment, the isolation valve 65 is arranged upstream of the air compressor 66. Alternatively, the isolation valve 65 is arranged downstream of the air compressor 66. The cathode gas subsystem 60 includes a cathode reactant portion 62 and a cathode bypass portion 64. The cathode reactant portion 62 provides an air flow to the cathode 54. A bypass valve 61 is connected to the cathode bypass portion 64, and control of the bypass valve 61 can be used to control the amount of air flowing through the cathode bypass portion 64 and the amount of air flowing through the cathode reactant portion 62. This control of the amount of air flowing through the cathode reactant portion 62 can be important for controlling the reaction of the fuel cell stack 50. The air exits through the air expander device 68 to the atmosphere 77. Flow through the air expander device 68 is controlled via a bleed valve 75, which is a flow control valve that is controllable to manage the flow of air to the fuel cell stack 50, including being controllable to block the flow of air between the fuel cell stack 50 and the atmosphere 77. In one embodiment, the bleed valve 75 is disposed upstream of the air expander device 68. Alternatively, the bleed valve 75 is disposed downstream of the air expander device 68.

[0077] As briefly mentioned above, during operation of the fuel cell stack 50, hydrogen enters the channels formed in the anode bipolar plate 42 and flows across the anode gas diffusion layer 40, the microporous layer 38, and the catalyst layer 36. Likewise, oxygen or air enters the channels formed in the cathode bipolar plate 48 and flows across the cathode gas diffusion layer 46, the microporous layer 45, and the catalyst layer 44. When the hydrogen entering the anode layer is oxidized, the hydrogen molecules electrocatalytically dissociate into protons and electrons, and the electrons flow in a circuit from the anode bipolar plate 42 through, for example, a load (not shown) to the cathode bipolar plate 48. At the same time, the remainder of the oxidized hydrogen atoms (which are protons) are transported across the fuel cell stack 50 from the anode 52 side to the cathode 54 side via the membrane 56, where they combine with the incoming air and the anode-induced electrons introduced into the circuit.

[0078] Figure 2 A method 200 is schematically illustrated, which may be used to perform a Figure 1The described embodiments of the fuel cell system 10 are implemented to provide a system and associated method that minimize or eliminate the risk of oxidation of carbon black particles contained in embodiments of the fuel cell stack 50 of the fuel cell system 10 during extended periods of inactivity (e.g., during transportation or long-term storage of the fuel cells).

[0079] Method 200 includes: manufacturing an embodiment of a fuel cell system 10, the fuel cell system including reference Figure 1 A fuel cell stack (FC stack) 50 is described in which a cathode (or alternatively, an anode) includes a carbon support and platinum-based catalyst nanoparticles dispersed on the carbon support (step 201).

[0080] In anticipation of transportation and / or storage of the fuel cell stack 50, the fuel cell stack 50 is purged with a premixed gas containing carbon monoxide (or CO) passing therethrough (step 202), and the fuel cell stack 50 is sealed to prevent intrusion of outside air into the fuel cell stack 50 during transportation and / or storage (step 203). Sealing the fuel cell stack 50 may include closing the exhaust valve 75.

[0081] In one embodiment, purging the fuel cell with a premixed gas containing carbon monoxide (or CO) therethrough (step 202) may include flowing a premixed gas containing carbon monoxide and hydrogen. In one embodiment, this may include purging both the anode and cathode with a mixture of carbon monoxide and hydrogen. Alternatively, this may include purging the anode with a mixture of carbon monoxide and hydrogen and purging the cathode with an inert gas (e.g., nitrogen, argon, or helium).

[0082] Hydrogen and carbon monoxide work together within the fuel cell stack 50. Hydrogen fixes the electrochemical potential of the platinum to zero volts and allows carbon monoxide to adsorb onto the platinum. Carbon monoxide is stable as long as hydrogen is nearby. By adsorbing carbon monoxide onto the platinum, the electrode is no longer active for the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER). The high diffusivity and high permeability of hydrogen relative to oxygen and the low concentration and low intrusion rate of oxygen confine oxygen to a small portion of the fuel cell for a period of time. When more oxygen leaks into the fuel cell, it reacts with hydrogen and carbon monoxide to some extent to produce water or CO2 and clean the platinum surface without causing carbon corrosion.

[0083] Flowing a premixed gas containing carbon monoxide and hydrogen may include flowing a premixed gas containing hydrogen (H2) and carbon monoxide (CO) at a volume ratio of 99.95% H2 to 0.05% CO. In one embodiment, this may include a premixed gas containing at least 10 parts per million (ppm) of CO in one embodiment.

[0084] In one embodiment, flowing the premixed gas containing carbon monoxide and hydrogen may include flowing a premixed gas containing at least a 0.1% concentration of CO through the fuel cell stack. In one embodiment, this may include a premixed gas containing at least 10 ppm of CO in one embodiment.

[0085] Alternatively, flowing a premixed gas containing carbon monoxide may include flowing a premixed gas containing carbon monoxide and nitrogen. In one embodiment, this may include a premixed gas containing at least 0.1% concentration of CO in one embodiment. In one embodiment, this may include a premixed gas containing at least 10 ppm of CO in one embodiment.

[0086] Alternatively, flowing a premixed gas containing carbon monoxide may include flowing a premixed gas containing carbon monoxide and argon. In one embodiment, this may include a premixed gas containing at least 0.1% concentration of CO in one embodiment. In one embodiment, this may include a premixed gas containing at least 10 ppm of CO in one embodiment.

[0087] Alternatively, flowing a premixed gas containing carbon monoxide may include flowing a premixed gas containing carbon monoxide and helium. In one embodiment, this may include a premixed gas containing at least 0.1% concentration of CO in one embodiment. In one embodiment, this may include a premixed gas containing at least 10 ppm of CO in one embodiment.

[0088] Alternatively, flowing a premixed gas containing carbon monoxide may include flowing a premixed gas containing another inert gas and helium. In one embodiment, this may include a premixed gas containing at least 0.1% concentration of CO in one embodiment. In one embodiment, this may include a premixed gas containing at least 10 ppm of CO in one embodiment.

[0089] The fuel cell stack 50 may be transported and / or stored (step 204). This may include assembling the fuel cell stack 50 into an embodiment of the fuel cell system 10 if this has not already occurred.

[0090] In this way, the fuel cell stack is protected from oxygen intrusion and associated corrosion of the carbon support of the second catalyst layer during storage by forcing carbon monoxide gas over the first catalyst layer and / or the second catalyst layer.

[0091] After the fuel cell stack 50 is removed from storage, the exhaust valve 75 is opened to unseal the fuel cell stack 50 (step 205), and a refresh operation is performed to purge CO from the fuel cell stack 50 (step 206). Performing a refresh operation to purge carbon monoxide from the fuel cell stack 50 includes flowing ambient air through the fuel cell stack 50. In one embodiment, this includes flowing ambient air through the cathode 54. In one embodiment, this includes flowing ambient air through the cathode 54 and flowing hydrogen through the anode 42 for a period of time with or without a small electrical load.

[0092] The fuel cell system 10 including the fuel cell stack 50 can be operated (step 207 ) to generate electricity for traction and other purposes.

[0093] In this way, the carbon support of the second catalyst layer of the fuel cell stack is protected from corrosion during storage by forcing carbon monoxide gas on the second catalyst layer before operation. Moreover, the carbon support of the second catalyst layer of the fuel cell stack can be protected from corrosion that might otherwise occur during storage by forcing carbon monoxide gas on the first catalyst layer and the second catalyst layer before operation.

[0094] For the sake of brevity, technologies related to signal processing, data fusion, signaling, control, and other functional aspects of the system (and the various operating components of the system) may not be described in detail herein. In addition, the connecting lines shown in the various figures contained herein are intended to represent example functional relationships and / or physical connections between the various elements. Alternative or additional functional relationships or physical connections may exist in embodiments of the present disclosure.

[0095] The term "controller" and related terms (such as microcontroller, control, control unit, processor, etc.) refer to one or various combinations of application specific integrated circuit(s) (ASICs), field programmable gate array(s) (FPGAs), electronic circuit(s), central processing unit(s) (e.g., microprocessor(s)), and associated non-transitory memory components in the form of memory and storage devices (read-only, programmable read-only, random access, hard drive, etc.). The non-transitory memory components are capable of storing machine-readable instructions in the form of one or more software or firmware programs or routines, combinational logic circuit(s), input / output circuit(s) and devices, signal conditioning, buffer circuit systems, and other components, which are accessible and executable by one or more processors to provide the described functions. The input / output circuit(s) and devices include analog / digital converters and related devices to monitor inputs from sensors, where such inputs are monitored at a preset sampling frequency or in response to a triggering event. Software, firmware, programs, instructions, control routines, code, algorithms, and similar terms mean sets of instructions executable by a controller, including calibration and lookup tables. Each controller executes (multiple) control routines to provide the desired functionality. Routines may be executed periodically, for example, once every 100 microseconds during ongoing operation. Alternatively, routines may be executed in response to the occurrence of a triggering event. Communication between controllers, actuators, and / or sensors may be achieved using a direct wired point-to-point link, a networked communication bus link, a wireless link, or another communication link. Communication includes exchanging data signals, including, for example, electrical signals via a conductive medium; electromagnetic signals via air; optical signals via optical waveguides; etc. Data signals may include discrete, analog, and / or digitized analog signals representing inputs from sensors, actuator commands, and communications between controllers.

[0096] The processes, methods, and procedures described below and in the accompanying drawings represent only functions that may be performed in a particular embodiment. In other embodiments, additional functions may be performed in the processes, methods, and procedures. Various embodiments of the present disclosure contemplate mechanisms for accomplishing the functions described herein. Some of the functions illustrated herein may be repeated, combined, modified, or deleted within the processes, methods, and procedures where appropriate. Additionally, functions may be performed in any suitable order within the processes, methods, and procedures without departing from the scope of a particular embodiment.

[0097] The detailed description and the accompanying drawings or figures support and describe the present teaching, but the scope of the present teaching is limited only by the claims. Although the best mode and some of other embodiments for implementing the present teaching have been described in detail, there are various alternative designs and embodiments for practicing the present teaching defined in the claims.

Claims

1. A method for operating a fuel cell system, the method comprising: assembling a fuel cell stack, the fuel cell stack including a bleed valve and an isolation valve; flowing a premixed gas containing carbon monoxide through the fuel cell stack; as well as Close the discharge valve and the isolation valve.

2. The method according to claim 1, further comprising: opening the discharge valve and the isolation valve; as well as A flushing operation is performed to purge the carbon monoxide from the fuel cell stack.

3. The method according to claim 2, wherein: Performing the flush operation to purge the carbon monoxide from the fuel cell stack includes flowing ambient air through the fuel cell stack.

4. The method according to claim 2, wherein: The fuel cell stack comprises an anode and a cathode; and Wherein, performing the refresh operation to purge the carbon monoxide from the fuel cell stack includes: flowing ambient air through the cathode.

5. The method according to claim 1, wherein: Flowing the premixed gas containing carbon monoxide through the fuel cell stack includes flowing a premixed gas containing carbon monoxide and hydrogen through the fuel cell stack.

6. The method according to claim 5, wherein: Flowing the premixed gas containing carbon monoxide and hydrogen includes flowing the premixed gas containing hydrogen (H 2 ) and carbon monoxide (CO) at a ratio of 99.9% H 2 to 0.1% CO.

7. The method according to claim 1, wherein: Flowing the premixed gas containing carbon monoxide through the fuel cell stack includes flowing a premixed gas containing carbon monoxide and nitrogen.

8. The method according to claim 1, wherein: Flowing the premixed gas containing carbon monoxide through the fuel cell stack includes flowing a premixed gas containing carbon monoxide and argon.

9. The method according to claim 1, wherein: Flowing the premixed gas containing carbon monoxide through the fuel cell stack includes flowing a premixed gas containing carbon monoxide and helium.

10. The method according to claim 1, wherein: Flowing the premixed gas containing carbon monoxide through the fuel cell stack includes flowing a premixed gas containing at least 0.1% CO concentration through the fuel cell stack.

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