Fuel cell information monitor and data transfer

Abstract

The fuel cell includes a membrane electrode assembly, first and second plate separators on opposite sides of the membrane electrode assembly, and a voltage sensor for detecting a cell voltage associated with each side of the membrane electrode assembly, with a transmitter coupled to the sensor and configured to wirelessly transmit an indication of the cell voltage.

Description

[Technical Field]

[0001] The present invention relates generally to methods and systems for monitoring fuel cell stacks, and more particularly to systems and methods for monitoring fuel cell stacks for variations in the electrical output and function of the fuel cells in the fuel cell stack system.

[0002] This application is further related to U.S. Patent Application No. 17 / 572,679 (Attorney Docket No. 1404.332), filed January 11, 2022, entitled "FUEL CELL STACK AND METHOD FOR MANUFACTURE," the disclosure of which is incorporated herein by reference.

[0003] This application is further related to U.S. patent application Ser. No. 17 / 663,097 (Attorney Docket No. 1404.334), filed May 12, 2022, entitled "INTEGRATED CIRCUIT FOR DIAGNOSTICS," the disclosure of which is incorporated herein by reference. [Background technology]

[0004] Fuel cells electrochemically convert fuel and oxidant into electricity and heat and can be classified according to the type of electrolyte (e.g., solid oxide, molten carbonate, alkaline, phosphoric acid, or solid polymer) used to provide ion transport during operation. Furthermore, fuel cell assemblies can be used in numerous environments (e.g., automotive, aerospace, industrial, and residential) for numerous applications.

[0005] Proton exchange membrane (hereinafter "PEM") fuel cells convert the chemical energy of a fuel, such as hydrogen, and an oxidant, such as air, directly into electrical energy. The PEM is a solid polymer electrolyte that allows the passage of protons (i.e., H+ ions) from the "anode" side of the fuel cell to the "cathode" side of the fuel cell while preventing the passage of reactant fluids (e.g., hydrogen gas and air gas). A membrane electrode assembly (hereinafter "MEA") is positioned between two conductive plates, each with flow channels that direct fuel to the anode side and oxidant to the cathode side of the PEM.

[0006] Two or more fuel cells can be connected together to increase the overall power output of the assembly. Typically, the cells are connected in series, with one side of a plate serving as the anode plate of one cell and the other side serving as the cathode plate of the adjacent cell. These are commonly referred to as bipolar plates (hereinafter "BPP"). Alternatively, the anode plate of one cell is electrically connected to the separate cathode plate of the adjacent cell. These two plates are typically connected back-to-back and often bonded together (e.g., by adhesive, welding, or polymer). This bonded pair is often referred to as a bipolar plate, since the anode and cathode plates electrically correspond to positive and negative electrodes. A number of such fuel cells connected in series are called a fuel cell stack. A stack typically includes means for directing fuel and oxidant into the anode and cathode flow field channels, respectively. The stack usually includes means for directing a coolant fluid into internal channels within the stack to absorb heat generated by the exothermic reaction of hydrogen and oxygen within the fuel cells. The stack typically includes means for exhausting excess fuel and oxidant gases as well as product water.

[0007] The stack also includes end plates, insulators, membrane electrode assemblies, gaskets, separator plates, electrical connectors, and collector plates, among other components, which are integrated to form a working stack designed to generate electricity. The various plates may abut and be interconnected to facilitate the performance of specific functions.

[0008] As previously mentioned, fuel cell stacks comprise many connected fuel cells. Monitoring individual cell voltages is important for system control and durability. For example, an underperforming cell can be the source of numerous failure mechanisms if not detected. Large stacks of fuel cells can sometimes contain hundreds of cells, and cell voltages for such cells are currently detected using individual wires, with the voltage signals multiplexed by integrated circuits. Managing these wires and their connections requires significant effort when assembling many fuel cells into a fuel cell stack, and significant voltage differences exist that must be managed within the electronics. Assembly of this system of cell voltage monitors significantly increases the assembly time and cost of the fuel cell stack.

[0009] Thus, there is a need for improved systems and methods for monitoring the operation of fuel cells in assembled fuel cell systems. Summary of the Invention

[0010] In a first aspect, the present invention provides a fuel cell comprising a membrane electrode assembly, first and second plate separators on opposite sides of the membrane electrode assembly, and a voltage sensor for detecting cell voltages associated with the opposite sides of the membrane electrode assembly, wherein a transmitter is coupled to the sensor and configured to wirelessly transmit an indication of the cell voltage.

[0011] In a second aspect, the present invention provides a method for use in monitoring a fuel cell comprising voltage sensors for detecting cell voltages associated with opposite sides of a membrane electrode assembly of the fuel cell, a transmitter coupled to the sensors for receiving an indication of the cell voltage from the voltage sensors, and the transmitter wirelessly transmitting the indication of the cell voltage. [Brief explanation of the drawings]

[0012] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of this specification. The foregoing and other features and advantages of this invention will be readily understood from the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings.

[0013] [Figure 1] 1 is a block diagram showing a fuel cell system according to the present invention;

[0014] [Figure 2] FIG. 2 is a perspective view showing a portion of the fuel cell of the fuel cell system of FIG. 1.

[0015] [Figure 3] 3 is a schematic side view of a portion of FIG. 2 further comprising a voltage sensor and a transmitter.

[0016] [Figure 4] FIG. 1 is a side schematic view showing multiple fuel cells connected to a voltage sensor and transmitter.

[0017] [Figure 5] FIG. 2 is a block diagram showing a battery voltage transmitter and receiver coupled to a controller.

[0018] [Figure 6] FIG. 1 is a side schematic view showing multiple fuel cells connected to multiple voltage sensors and transmitters.

[0019] [Figure 7]FIG. 3 is an exploded view of the fuel cell of the system of FIG. 2 with the seals removed for clarity.

[0020] [Figure 8] 4 is a vertical cross-sectional view of a portion of the fuel cell system of FIG. 3 with metallized traces on a subgasket connected to the gas diffusion layer of the system.

[0021] [Figure 9] 4 is a vertical cross-sectional view of a portion of the system of FIG. 3 showing metallized traces on a subgasket connected to a gas diffusion layer.

[0022] [Figure 10] 4 is a vertical cross-sectional view of a portion of the fuel cell system according to FIG. 3, in which the metallized traces on the subgasket have upwardly protruding portions.

[0023] [Figure 11] 4 is a vertical cross-sectional view of a portion of the fuel cell system according to FIG. 3, in which the metallized traces on the subgasket have upwardly protruding portions.

[0024] [Figure 12] 3 is a perspective view of a subgasket having tabs and receiving a membrane electrode assembly according to an embodiment of the present invention. FIG.

[0025] [Figure 13] FIG. 13 is an enlarged perspective view of the tab of FIG. 12.

[0026] [Figure 14] 1A and 1B are perspective cross-sectional views illustrating multiple subgaskets receiving membrane electrode assemblies having tabs at different locations, according to an embodiment of the present invention.

[0027] [Figure 15] Exploded view of the subgasket in Figure 14.

[0028] [Figure 16]FIG. 2 is a top view of a subgasket having multiple traces in accordance with an aspect of the present invention.

[0029] [Figure 17] 4 is a vertical cross-sectional view of a portion of the fuel cell system of FIG. 3 with metallized traces on the subgasket connected to the system's gas diffusion layers and to external monitoring or control devices, according to an embodiment of the invention.

[0030] [Figure 18] FIG. 2 is a top view of a subgasket with thermocouple junctions formed from metal traces, according to an aspect of the present invention.

[0031] [Figure 19] 19 is a vertical cross-sectional view of a fuel cell system with the thermocouple junction of FIG. 18.

[0032] [Figure 20] 1 is a vertical cross-sectional view of a fuel cell system with multiple fuel cells, where a device is connected to multiple fuel cells of the system to power the device, according to an embodiment of the invention.

[0033] [Figure 21] FIG. 2 is a side schematic view of a voltage monitor and transmitter. Detailed Description of the Invention

[0034] The present invention will be discussed in detail below with reference to various exemplary embodiments according to the present invention, with reference to the accompanying drawings. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known structures are not shown in detail to avoid unnecessarily obscuring the present invention.

[0035] Accordingly, all implementations described below are example implementations provided to enable any person skilled in the art to make or use embodiments of the present disclosure, and are not intended to limit the scope of the present disclosure, which is defined by the claims. As used herein, the words "exemplary" or "illustrative" mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" or "illustrative" is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, in the description in this section, the terms "upper," "lower," "left," "rear," "right," "front," "vertical," "horizontal," and their derivatives refer to the present invention in the orientation in FIG. 1 .

[0036] Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary, or the following detailed description. Also, it is to be understood that the specific devices and processes illustrated in the attached drawings, and described in the following specification, are merely exemplary embodiments of the inventive concepts defined in the appended claims. Hence, specific dimensions and other physical characteristics relating to the embodiments disclosed herein are not to be considered limiting, unless the claims expressly state otherwise.

[0037] In accordance with the principles of the present invention, a fuel cell system and method for manufacturing a fuel cell stack are provided. In the example shown in FIG. 1 , a fuel cell system 101, referred to as an assembled system or complete system, functionally produces electricity with all of its components and typically includes a fuel cell stack 20 and an energy storage device 30. The fuel cell is supplied with fuel 13, e.g., hydrogen, through a fuel inlet 17. Excess fuel 18 is exhausted from the fuel cell through a purge valve 90 and may be diluted by a blower 40. In one example, the fuel cell stack 20 may have an open cathode configuration of a PEM fuel cell, and a combination of oxidant and coolant, e.g., air, may enter through an inlet air filter 10 connected to an inlet 5 of the fuel cell stack 20. Excess coolant / oxidant and heat are exhausted from the fuel cell cathodes of the fuel cell stack 20 through an outlet 11 to a blower 40, which may exhaust the coolant / oxidant and / or excess fuel to waste exhaust 41, e.g., ambient atmosphere. The fuel and coolant / oxidant may be supplied by a fuel supply 7 and an oxidant supply 9 (e.g., air), respectively, and by other components of the peripheral equipment, which may include compressors, pumps, valves, blowers, electrical connections, and sensors.

[0038] 2 is a schematic exploded view showing an internal subassembly 100 of the fuel cell stack 20 of FIG. 1, including a cathode plate separator 110 at its outer end 115 and an inner plate separator seal 120. A membrane electrode assembly (MEA) 130 is located between the seal 120 and a second plate separator seal 150. An anode plate separator 160 is at a second end 165 of the subassembly 100.

[0039] The MEA 130 includes a membrane 140 (e.g., an ion-conducting membrane) between a cathode catalyst layer 125 and an anode catalyst layer 135. A cathode gas diffusion layer (GDL) 122 is located between the cathode catalyst layer 125 and the plate separator 110 of the membrane electrode assembly. An anode gas diffusion layer 145 is located between the anode catalyst layer 135 and the plate separator 160 of the membrane electrode assembly. The seals 120 and 150 may be received in channels inside the plate separator 110 and the plate separator 160, respectively. Alternatively, such seals may be injection molded around the MEA (e.g., MEA 130) or another fuel cell component, as described below. Alternatively, such seals may be injection molded around the MEA (e.g., MEA 130) or another fuel cell to provide a sealing function, for example, between the MEA and a fuel cell plate separator.

[0040] In the example shown in FIG. 3, the voltage sensor 900 may be electrically connected to opposing bipolar plates 102 , such as plate separator 110 and plate separator 160 of subassembly 100 of fuel cell stack 20 .

[0041] The sensor 900 can detect and / or measure the voltage potential between the plate separator 110 and the plate separator 160. The sensor 900 can be electrically connected to a transmitter 910 that can be configured to wirelessly transmit an indication of the detected or measured voltage.

[0042] While shown as separate, in one example, the sensor 900 and transmitter 910 could be the same device, e.g., a light-emitting diode (LED). When a predetermined amount of voltage (e.g., per the specifications of a particular LED) exists between opposing bipolar plates, e.g., between plate separator 110 and plate separator 160, light can be emitted by the transmitter 910 (e.g., an LED) to indicate to a user that the voltage between the aforementioned plate separators is within an acceptable range. For example, such an LED could illuminate only when a certain amount of voltage (e.g., greater than approximately 0.6 V) is present, thereby notifying a user that at least that certain amount of voltage has been detected by the sensor. The sensor and transmitter (e.g., an LED) could also be separate devices electrically connected to each other as shown.

[0043] As shown in FIG. 4 , a sensor (e.g., sensor 900) can be electrically connected to various plates or plate separators within a fuel cell stack (e.g., fuel cell stack 20) to provide information about two or more fuel cells in the stack. For example, such sensors can be connected to plates on either side of a plurality of fuel cells, such as sets of two, three, five, or ten fuel cells, to provide voltage and other information about the group of fuel cells. As shown in FIG. 4 , sensor 900 can be electrically connected via connecting wires 901 to plate separator 160 and plate separator 111 spaced apart from one or more other bipolar plates (e.g., bipolar plate 102) of a fuel cell in the fuel cell stack (e.g., fuel cell stack 20). Connecting a sensor (e.g., sensor 900) to multiple fuel cells allows a user to observe, or a controller to obtain information about, the multiple fuel cells within the stack (e.g., fuel cell stack 20). For example, the illumination of LEDs electrically connected to sensors (e.g., sensor 900) coupled to various fuel cells or fuel cell sets would provide an observer or user with information as to which fuel cells or fuel cell sets in the stack are operating correctly or efficiently. Alternatively, an LED or LED set could be configured to illuminate a particular color depending on whether the fuel cell or fuel cell set is operating at a particular voltage or has other operating characteristics (e.g., current).

[0044] In another example, the transmission or emission of information (e.g., light emitted by an LED) by a transmitter 910 coupled to the sensor 900 may be received by a receiver 920 coupled to a controller 930 configured to control aspects of the system 101 and / or stack 20, as shown in Figure 5. Such information transmission can be via an LED emitting light to a light sensor, an RF transmitter transmitting to an RF receiver, a cell transmitter transmitting to a cell receiver, a near field communication (NFC) sender and receiver, or other such wireless technologies.

[0045] As previously mentioned, a transmitter (e.g., transmitter 910) equipped with an LED may simply transmit light to indicate whether a fuel cell or set of fuel cells is or is not operating acceptably. In other examples, additional information may be conveyed by a particular light transmission. For example, via pulse width modulation, information may be conveyed from a transmitter (e.g., transmitter 910) to a receiver (e.g., receiver 920) and a controller (e.g., controller 930), such as a particular voltage provided or other information provided to the sensor and / or transmitter by other sources within the fuel cell stack. For example, the particular location of a particular fuel cell or group of fuel cells within a fuel cell stack (e.g., fuel cell stack 20) may be coupled with the particular voltage of each cell and transmitted wirelessly (e.g., via pulse width modulation) from the transmitter to the receiver. In such a situation, a user may be notified of the voltage of a particular cell within the fuel cell stack, which may enable maintenance to be performed on a particular fuel cell within the stack and / or other maintenance to be performed or scheduled.

[0046] FIG. 6 shows an example of three LEDs 1000 electrically connected (e.g., via connecting wires 1005) to various plate separators (e.g., bipolar plates 102) within a fuel cell stack (e.g., fuel cell stack 20). Each of the LEDs 1000 can detect the total voltage of the stack's fuel cells, i.e., each of the LEDs can illuminate when a specific voltage is present. For example, a red LED 1001 among the LEDs 1000 can illuminate above 1.8 V and can be connected to and used to measure three fuel cells in the stack. If one or more of the cells connected to the red LED are operating at a low potential, the set of three fuel cells can be identified by an unlit LED (e.g., an unlit red LED). Such a configuration of multiple fuel cells connected to a single LED may be implemented, for example, for all cells in a stack (e.g., fuel cell stack 20). In this case, an array of multiple such LEDs could identify individual poorly performing fuel cells in the fuel cell stack (e.g., by an unlit LED). 6, the receivers 1100 may further be light sensors utilized to determine whether designated LEDs are illuminated. As noted above, such receivers may be electrically (e.g., wired or wirelessly) coupled to a controller (e.g., controller 930) to share such information with the controller.

[0047] 7 shows the repeating portion 103 of the internal subassembly 100 in an exploded view similar to FIG. 2, but without the seals (i.e., seals 120 and 150) and without the cathode plate separator 110 for clarity. A seal or subgasket 300 is located between the cathode catalyst layer 125 and the anode catalyst layer 135, and the membrane 140 is received in a cavity 146 of the subgasket 300. A gasket or seal 170 may be located below the plate separator 160.

[0048] As previously mentioned, the membrane 140 can be received in the opening 146 of the subgasket 300, which can be formed of a non-conductive material such as a polymer. As shown, the MEA 130 can be attached to the anode-side GDL 145, and the combined MEA 130-GDL 145 can be sandwiched with the GDL 122 around the subgasket 300 so that the components adhere to one another. For example, this combination can be formed by hot pressing the aligned anode and cathode portions (e.g., the MEA 130-GDL 145 and GDL 122) to adhere them to the subgasket 300. In one example, a heated platen can hold the gas diffusion layers (gas diffusion layers 122, 145) and the membrane electrode assembly 130 while they are bonded to the subgasket 300 (e.g., via a heat-sensitive adhesive or by bonding the gas diffusion layers to the MEA).

[0049] 8 , metal trace 200 can be connected to GDLs (e.g., GDL 122 and GDL 145) on either side of a membrane (e.g., membrane 140). As shown, a first, upper trace 205 of trace 200 is attached to and positioned on a first side (e.g., the top side in the drawing) 301 of subgasket 300, while a second, lower trace 207 is attached to and positioned on a second side 302 of subgasket 300 and can extend vertically through the subgasket (e.g., through a via) to first side 301. Metal traces (e.g., trace 200) can be printed onto a subgasket (e.g., subgasket 300) during a metallization printing process or by another method of depositing metallic or other conductive strips or traces onto a gasket (e.g., vacuum metallization, arc or flame spraying, plating). After an opening or via is provided through the subgasket, a metal or other conductive material may be printed or otherwise positioned in the opening to form a metallized via, allowing the lower trace (e.g., second trace 207) to have an upwardly extending portion 203 that extends through the gasket (e.g., gasket 300).

[0050] Trace 200 may include an electrical connector 201 (e.g., formed of a conductive metal or the same material as trace 200) at the end opposite the GDLs (e.g., GDLs 122 and 145) to allow the trace (e.g., trace 200) and therefore the GDLs to be electrically connected to one or more controllers, sensors, or other devices external to subassembly 100. For example, the trace may be connected to a voltage sensor or computerized controller.

[0051] As discussed above, traces 200 may connect to GDLs (e.g., GDLs 122 and 145) and provide an electrical connection between the GDLs and connector 201, thereby enabling external connections to the GDLs for purposes of monitoring and / or controlling subassembly 100 and fuel cell stack 20. For example, subgasket 300 and traces 200 may extend from GDLs 122 and / or GDLs 145 toward the exterior of subassembly 100. Subgasket 300 and traces 200 may extend outward, for example, past the outermost or outer edge 111 of plate separator 110 and / or the outermost or outer edge 161 of plate separator 160. It is also contemplated that connector 201 may be located outside of outer edge 111 and / or outer edge 161 as shown. Locating the connectors outside the plate separator and seal 120 and / or seal 150 allows for more spacing (because they are located on the outside) and makes it easier to connect the connectors to external devices such as sensors and controls.

[0052] FIG. 9 shows a portion of FIG. 8, including portions of the top trace 205, plate separator 110, GDL 122, membrane 140, and subgasket 300. The top trace 205 extends between the subgasket 300 and the seal or gasket 120 and is received beneath the GDL 122 and above the subgasket 300. More specifically, the GDL-side end 206 of the top trace 205 opposite the connector 201 contacts, or may be connected to, the GDL 122 to provide a connection between the GDL 122 and the top trace 205, thereby providing an electrical connection between the GDL 122 and the first connector 202 of the connectors 201 (FIG. 5). The second trace 207 can extend between the subgasket 300 and the seal or gasket 150 and be received beneath the GDL 145 and above the subgasket 300, as shown in FIG. 5, for example. Additionally, the second traces 207 may extend through the subgasket as described above.

[0053] 10 , the first trace 205 may include a vertically extending spike 210 at or near the end 211 of the trace 205 to allow the trace 205 to penetrate deeper into the GDL 122 compared to the laterally extending portion 212 and end 211 of the trace 205. The spike 210 may extend into the GDL 122 (but may not extend through the GDL 122 into the plate separator 110) to improve (due to its larger surface area and dimensions) the electrical connection of the trace 205, and therefore the connector 202, to the GDL 122. The first trace 205 with the spike 210 may be formed during the formation of the first trace 205 or in a subsequent step by depositing (e.g., printing) additional metal or other conductive material onto the trace 205 to form the spike 210. For example, the spike 210 may be formed by stamping the metallized plastic forming the trace 205. Additionally, spikes 210 may be formed by bending and cutting such metallized plastic. Second traces 207 (not shown in FIG. 10) can extend between subgasket 300 and seal or gasket 150 and be received under GDL 145 and above subgasket 300, for example, as shown in FIG. 5. Additionally, second traces 207 can extend through the subgasket as described above.

[0054] 11 , in comparison to the above description, trace 208 is substituted for first trace 205, and upwardly extending portion 209 of trace 208 may extend upward from portion 204 of trace 208 connected to subgasket 300 at a position transverse to GDL 122, such that trace 208 does not extend between gasket 120 and subgasket 300. Upwardly extending portion 209 of trace 208 may be formed by the method described for spike 210 and may extend upward to contact plate separator 110. In comparison to the above description, a second trace (not shown) may be substituted for second trace 207 and may be positioned to extend along the opposite side of subgasket 300 perpendicular to trace 208 and may similarly extend downward to contact plate separator 160. Such a second trace could also extend through subgasket 300 in the same manner as trace 207.

[0055] 12-13, subgasket 305 can be connected to MEA 330 and trace 310 can be received on subgasket 130, similar to that described above with respect to subgasket 300, MEA 130, and trace 205. Additionally, subgasket 305 can include protruding tab 340, and trace 310 can extend from GDL 312 similar to GDL 122 and GDL 145 described above. Additionally, a second trace (not shown) can be located on the opposite side of subgasket 305, similar to trace 207 described above. Connector 350 can be positioned on subgasket 305 (e.g., tab 340) to connect to the trace, allowing an external device (e.g., a voltage sensor or electronic controller) to connect to the trace and thus to the GDLs (not shown) on either side of the MEA. Tab 340 can have a longitudinal dimension extending away from the remainder of gasket 305 and the fuel cell stack (e.g., fuel cell stack 20) that is sized (in conjunction with its lateral dimension) to allow connector 350 to be spaced from the outer surface or casing of the subassembly (e.g., subassembly 100) or fuel cell stack (e.g., fuel cell stack 20). Such spacing can facilitate connection to devices and / or manipulation of devices connected to the connector. Additionally, tab 340 can have a lateral width dimension that is shorter than the longitudinal dimension, which can allow multiple such tabs to be positioned laterally adjacent to one another to facilitate multiple connections to various fuel cells or other components of the fuel cell stack (e.g., fuel cell stack 20).

[0056] 14-15 show multiple subgaskets 500 similar to subgasket 305, but each having tabs 510 (similar to tabs 340) at different locations, i.e., side-by-side, along the longitudinal dimension of the gasket (with its edges aligned) and associated subassembly or fuel cell stack (e.g., fuel cell stack 20). As shown, the side-by-side tab locations can facilitate connection to multiple devices (e.g., sensors or controllers) along the longitudinal dimension of the gasket and can provide space for connection to such devices (e.g., by extending the tabs longitudinally from the rest of the fuel cell stack and by having the tabs side-by-side) and / or space between the tabs to allow the devices to function better.

[0057] 16 illustrates another example subgasket 550, similar to subgaskets described above (e.g., subgasket 300, subgasket 305, subgasket 500), except that subgasket 550 has a plurality of conductive traces attached thereto by metallization printing or other deposition. For example, subgasket 550 can include a plurality of traces 560 that extend to various locations along subgasket 550 to enable electrical connection between such locations and connectors 570 on tabs 580, similar to the tabs described above (e.g., tabs 340, 510). Furthermore, such traces (e.g., traces 560) can lead from tabs 580 to sensors or other devices located on or adjacent to subgasket 550.

[0058] FIG. 17 is identical to FIG. 8 except that device 600 is connected to connector 201 of subassembly 100. In one example, device 600 could be a voltage sensor. By connecting traces (e.g., traces 205, 207) to GDLs (e.g., GDLs 122 and 145), such a sensor could measure the voltage across the membrane (e.g., membrane 140), forming a circuit that is powered by the fuel cell (e.g., subassembly 100), e.g., 0.2-0.9 V when operating properly. Device 600 could also be an electronic controller, temperature sensor, or other device for monitoring a fuel cell stack (e.g., fuel cell stack 20).

[0059] In the example shown in FIGS. 18-19 , the subgasket 650 includes a first trace 660 and a second trace 670 formed of dissimilar metals such that a temperature difference causes a change in electrical potential, thereby creating a thermocouple junction 680. More specifically, the second trace 670 can overlie the first trace 660 and the thermocouple junction 680, such that a change in temperature can be sensed through an electrical connection between the first and second traces. As shown in FIG. 16 , a seal 690 can electrically insulate the thermocouple junction 680 from the GDL 122. In some examples, an increase or decrease in temperature can be sensed through the electrical connection between the first trace 660 and / or the second trace 670 and the GDL 122.

[0060] As shown in FIG. 20, device 700 can be electrically connected to the tabs (e.g., tab 340, tab 510, FIGS. 11-12) of multiple fuel cells in a fuel cell stack (e.g., fuel cell stack 2). This connection to multiple fuel cells in the stack can provide sufficient power to power a device such as device 700, which can be used to measure aspects of the fuel cell stack, control components of the stack (e.g., motors or peripherals), or provide other necessary functionality. Similarly, a device such as device 700 could be used to perform measurements on a stack powered by a stack at a higher potential.

[0061] In the example shown in FIG. 21 , an integrated circuit 1190 can be connected to metal traces 1200 that are connected to GDLs (e.g., GDLs 122 and 145) on either side of a membrane (e.g., membrane 140). The traces connecting to the GDLs allow integrated circuit 1190 to measure the voltage on either side of the membrane, and the circuit thus formed is powered by a fuel cell (e.g., subassembly 100), e.g., 0.2-0.9 V when operating properly. Integrated circuit 1190 can be connected to or include a transmitter 1210 (e.g., an LED powered by a step-up DC / DC converter such as the Analog Devices LTC3105) configured to wirelessly transmit an indication of the voltage to a receiver 1220 (e.g., a light sensor). The integrated circuit 1190 and transmitter 1210 can transmit information about the measured voltage via an LED configured to light up at a specific voltage (e.g., above 0.6 V), or the specific voltage and / or other related information (e.g., temperature, impedance, or part number) can be transmitted via pulse width modulation or another means of wirelessly transmitting such information to a receiver (e.g., receiver 1220). The integrated circuit 1190 can also include or be coupled to a controller that receives data from one or more fuel cells and enables the processing that causes such data to be transmitted via pulse width modulation. As described above, the membrane 140 can be formed on a web (e.g., web 300) as part of an MEA (e.g., MEA 130) and can have metal traces (e.g., trace 1200) printed on the web (e.g., web 300) during a web-based manufacturing process. Additionally, a seal or gasket 1230 can be present between the sensor 1190 and the GDL (e.g., GDL 122).

[0062] As described above, a transmitter (e.g., transmitter 910, LED 1000, transmitter 1210) connected to a sensor (e.g., sensor 900, integrated circuit 1190) for indicating cell voltage across one or more fuel cells in a fuel cell stack can be an LED or another wireless transmitter that can be wirelessly coupled to a receiver (e.g., receiver 930, receiver 1100, receiver 1220) or simply provide a visual indication of such voltage (e.g., via a colored LED). Compared to other methods for transmitting fuel cell information from a fuel cell to a remote location, the use of LEDs has a low forward voltage, e.g., 1.2V-3.0V, and LED diodes are less prone to reverse current. LEDs avoid problems with radio frequency interference and allow for simple signal processing. LEDs can be made smaller and can include low-cost circuitry with existing, commercially available components.

[0063] Various other time-based digital transmission techniques can be utilized between a voltage sensor (e.g., sensor 900, integrated circuit 1190) and / or a transmitter (e.g., transmitter 910, transmitter 1210) and a receiver (e.g., receiver 930, receiver 1100, receiver 1220) via an LED coupled to a controller (e.g., part of sensor 1190) that generates digital communication between such transmitter and receiver. For example, such communication techniques can include pulse-width modulation (PWM), which may be time-based and limited to a single analog value. Alternatively, such digital communication can be by frequency modulation, where the frequency of the pulse conveys an analog value. Asynchronous digital communication can use a single LED to pass data (e.g., voltage, status, serial number). Synchronous (i.e., clocked) digital communication utilizes at least a second LED to enable timing of the data (e.g., voltage, status, serial number). Various types of information can be transmitted from the sensor and received by a receiver coupled to the controller via digital communication techniques, as described above. Voltage or other information (e.g., temperature, impedance, gas concentration, part number, or quality control information such as lot number, supplier, and other manufacturing information) can also be transmitted from an integrated circuit on the fuel cell stack transmitting the voltage to a receiver remote from such fuel cell stack or remote from a particular portion of such fuel cell stack by an inductive transmit / receive coil, RF transceiver, NFC transceiver, Bluetooth transceiver, Wi-Fi transceiver, or other such wireless technology. Figure 18 shows an example of an inductive transmit coil 1150 and an inductive receive coil 1160 that can be used for such purposes.

[0064] In another example, a transmitter (e.g., transmitter 910, transmitter 1210) for transmitting information about a fuel cell remotely from the fuel cell may be a low-voltage incandescent light bulb or a liquid crystal configured to emit a light amount or brightness based on the amount of voltage or other parameter detected by a sensor (e.g., sensor 900, integrated circuit 1190), and a receiver (e.g., receiver 930, receiver 1100, receiver 1220) may be configured to monitor such brightness corresponding to the amount of voltage or other such information. For example, the receiver (e.g., receiver 930, receiver 1100, receiver 1220) may be a Si photodiode array for detecting position or other information from an illuminated LED. Furthermore, the above-described transmitter and receiver may be positioned inside a fuel cell housing that holds a fuel cell stack (e.g., fuel cell stack 20), or such a transmitter may be positioned inside the fuel cell stack, and the transmitter may be located remotely from the stack but within a range and otherwise in a position that allows wireless transmission of information therebetween (e.g., within line of sight for optical transmission).

[0065] In an example not shown, it is contemplated that the tabs (e.g., tab 340, tab 510) may have outermost or lateral edges that are electrically conductive (e.g., may have a conductive material such as a metal printed or otherwise deposited thereon) and connectable to traces (e.g., traces 205, 208, 208, 310, 560) as described above that may connect to interior sides of the fuel cell stack (e.g., fuel cell stack 20). Such electrically conductive tabs may be vertically aligned to allow electrical connections between the tabs that allow electrical connections between vertical or lateral portions of the fuel cell stack (e.g., fuel cell stack) to facilitate connection of sensors and / or controllers to the various portions of the stack as described above.

[0066] Fuel cell subassembly 100 can be manufactured using methods based on using webs or plastic sheets to connect components of a fuel cell stack (e.g., fuel cell stack 20) during its manufacture, such as those described in commonly assigned U.S. patent application Ser. No. 17 / 572,679, filed Jan. 11, 2022. Alternatively, assembly 100, or portions thereof, can be manufactured manually or by a combination of the automated and manual methods described above.

[0067] Although the above-described examples of conductive traces (e.g., trace 200, trace 205, trace 207, trace 208, trace 310, trace 560) refer to traces that are printed, deposited, or otherwise attached to, connected to, or adjacent to plate separator 110, GDL 122, and membrane 140, the methods of connecting such traces can be utilized with the other plate separators, GDLs, and systems described herein. For example, such traces may be placed on other subgaskets that are connected to MEAs in multiple fuel cells of a fuel cell stack (e.g., fuel cell stack 20).

[0068] While several embodiments of the present invention have been described and illustrated herein, those skilled in the art may devise alternative embodiments to accomplish the same purposes, and it is therefore intended by the appended claims to cover all such alternative embodiments which fall within the true spirit and scope of the invention.

Claims

1. a membrane electrode assembly; a first plate separator and a second plate separator on opposite sides of the membrane electrode assembly; voltage sensors for detecting cell voltages associated with opposite sides of the membrane electrode assembly; a transmitter coupled to the sensor and configured to wirelessly transmit an indication of the battery voltage; A fuel cell system comprising:

2. The system of claim 1 , wherein the indication comprises an emission of light by the transmitter.

3. 3. The system of claim 2, wherein the indication includes the emission of a light by the transmitter when the battery voltage is greater than a predetermined minimum voltage.

4. 10. The system of claim 1, wherein the voltage sensor is electrically connected to the first plate separator and the second plate separator, and the first plate separator and the second plate separator comprise bipolar fuel cell plates.

5. The system of claim 1 , further comprising a plurality of fuel cells, wherein a first fuel cell of the plurality of fuel cells comprises the first plate separator, the second plate separator, and the membrane electrode assembly.

6. 6. The system of claim 5, wherein the voltage sensor is electrically connected to a second fuel cell of the plurality of fuel cells, and the voltage sensor is configured to detect a cell voltage associated with a first side of the membrane electrode assembly and a second side of a second membrane electrode assembly of the second fuel cell.

7. The system of claim 6 , wherein the transmitter is configured to transmit information related to a position of a first fuel cell in a fuel cell stack.

8. 7. The system of claim 6, further comprising a third fuel cell between the fuel cell and the second fuel cell.

9. The system of claim 1 , wherein the transmitter comprises an LED.

10. The system of claim 1 , wherein the transmitter transmits the indication by digital communication.

11. The system of claim 1 , wherein the transmitter transmits the indication and the position of the first plate separator and / or the second plate separator by digital communication.

12. 10. The system of claim 1, wherein the transmitter includes an LED that transmits the emitted light indication using digital communications.

13. 10. The system of claim 1, wherein the transmitter transmits the indication by emitting light of a predetermined brightness based on the voltage.

14. The system of claim 1 , further comprising a receiver spaced apart from the transmitter and configured to wirelessly receive the indication from the transmitter.

15. 1. A method for use in monitoring a fuel cell, comprising: a voltage sensor detecting a cell voltage associated with each side of a membrane electrode assembly of the fuel cell; a transmitter coupled to the sensor receiving an indication of battery voltage from the voltage sensor; the transmitter wirelessly transmitting an indication of the battery voltage; A method comprising:

16. The method of claim 15 , wherein the step of transmitting the indication includes a transmitter emitting light to transmit the indication.

17. 16. The method of claim 15, wherein the step of transmitting an indication includes the transmitter emitting a light when the battery voltage is greater than a predetermined minimum voltage.

18. 16. The method of claim 15, wherein the fuel cell is a first fuel cell of a plurality of fuel cells, and wherein detecting the cell voltage comprises detecting cell voltages associated with the first fuel cell and a second fuel cell of the plurality of fuel cells.

19. The method of claim 15 , wherein the transmitter transmits the indication by digital communication.

20. 20. The method of claim 18, further comprising: a receiver spaced apart from the transmitter, the receiver wirelessly receiving the indication.

21. 16. The method of claim 15, further comprising: a receiver spaced apart from the transmitter, the receiver wirelessly receiving the indication.

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