Method of manufacturing an integrated water vapor transfer device and fuel cell-II

The present disclosure provides a method for manufacturing an integrated MEA, the method includes the following steps: (1) providing a substrate having an AA region and a WVT region; (2) simultaneously coating a microporous layer, a catalyst layer, and a first membrane ionomer layer onto the substrate; (3) applying an optional membrane support layer to the first membrane ionomer layer in the AA region and the WVT region; (4) applying an optional second membrane ionomer layer; (5) heating treating a coated substrate; and (6) assembling the coated substrate to a companion coated substrate.

TECHNICAL FIELD

The invention relates to a method of manufacturing an integrated membrane electrode assembly (MEA) having a water vapor transfer (WVT) region.

BACKGROUND

Fuel cell stack systems are used as power sources for electric vehicles, stationary power supplies, and other applications. One known fuel cell stack system is the proton exchange membrane (PEM) fuel cell stack system that includes a membrane electrode assembly (MEA) comprising a thin, solid polymer electrolyte membrane having an anode on one face and a cathode on the opposite face. The MEA is sandwiched between a pair of electrically conductive contact elements which serve as current collectors for the anode and cathode, which may contain appropriate channels and openings therein for distributing the fuel cell stack system's gaseous reactants (i.e., H2 and O2 or air) over the surfaces of the respective anode and cathode.

PEM fuel cells comprise a plurality of the MEAs stacked together in electrical series while being separated by an impermeable, electrically conductive contact element known as a bipolar plate or current collector. The fuel cell stack systems are operated in a manner that maintains the MEAs in a humidified state. The level of humidity of the MEAs affects the performance of the fuel cell stack system. Additionally, if an MEA is operated too dry, the performance and useful life of the MEA can be reduced. To avoid drying out the MEAs, the typical fuel cell stack systems are operated with the MEA at a desired humidity level, wherein liquid water is formed in the fuel cell during the production of electricity. Additionally, the cathode and anode reactant gases being supplied to the fuel cell stack system are also humidified to prevent the drying of the MEAs in the locations proximate the inlets for the reactant gases. Traditionally, a water vapor transfer (WVT) unit is utilized to humidify the cathode reactant gas prior to entering into the fuel cell. See, for example, U.S. Pat. No. 7,138,197 by Forte et al., incorporated herein by referenced in its entirety, a method of operating a fuel cell stack system.

The basic components of a PEM-type fuel cell are two electrodes separated by a polymer membrane electrolyte. Each electrode is positioned on opposite sides of the membrane as a thin catalyst layer. Similarly, on each side of the assembly adjacent to each thin catalyst layer, a microporous layer (MPL) is coated on a gas diffusion substrate to produce a gas diffusion layer wherein the gas diffusion layer is the outermost layer on each side of the membrane electrode assembly (MEA). The gas diffusion substrate is commonly composed of non-woven carbon fiber paper or woven carbon cloth. The GDL is primarily provided to enable conductivity, and to allow gases to come in contact with the catalyst. The GDL works as a support for the catalyst layer, provides good mechanical strength and easy gas access to the catalyst and provides the electrical conductivity. The purpose of the microporous layer is to minimize the contact resistance between the GDL and catalyst layer; limit the loss of catalyst to the GDL interior and help to improve water management as it provides effective water transport. Accordingly, the electrodes (catalyst layers), membrane, microporous layers, and gas diffusion layer together form the membrane electrode assembly (MEA). The MEA is generally disposed between two bipolar plates to form a fuel cell arrangement.

As is known, hydrogen is supplied to the fuel cells in a fuel cell stack to cause the necessary chemical reaction to power the vehicle using electricity. One of the byproducts of this chemical reaction in a traditional fuel cell is water in the form of vapor and/or liquid. It is also desirable to provide humid air as an input to the fuel cell stack to maximize the performance output for a given fuel cell stack size. Humid air also prevents premature mechanical and chemical degradation of the fuel cell membrane.

The input air is typically supplied by a compressor while a water transfer device external to the stack is traditionally implemented in a fuel cell system to add moisture to the input air supplied by a compressor, the source of the moisture often coming from the product-water-laden stack cathode outlet stream. These components among many other components in a traditional fuel cell system contribute to the cost of the fuel cell system and also require packaging space. In many applications, such as but not limited to a vehicle, packaging space is limited.

Accordingly, there is a need to integrate components of a fuel cell system where possible at a reasonable cost.

SUMMARY

The present disclosure provides a method for manufacturing a membrane electrode assembly (MEA) having an integrated water vapor transfer (WVT) region wherein certain layers of the MEA are simultaneously stripe-coated. The first embodiment method includes the following steps: (1) providing a substrate having an active area (AA) region and a WVT region; (2) simultaneously coating a microporous layer (MPL), a catalyst-containing layer, and a first membrane ionomer layer onto the substrate; (3) optionally applying a membrane support layer to the first membrane ionomer layer in the AA region and the WVT region; (4) optionally applying a second membrane ionomer layer; and (5) heat treating the coated substrate formed by the substrate and a plurality of layers; and (6) assembling the coated substrate to a companion coated substrate. A multi-layer slot-die coating tool may be implemented to apply or coat the microporous layer, the catalyst layer, and the first membrane ionomer layer simultaneously onto the substrate wherein the substrate is a gas diffusion media.

With respect to all embodiments of the present disclosure, the coated substrate may be heat-treated before assembling the coated substrate to a companion coated substrate. A die-coating tool may be implemented to apply or coat the microporous layer, the catalyst-containing layer, and the first membrane ionomer layer simultaneously onto the substrate wherein the substrate is a gas diffusion media. Moreover, with respect to all embodiments of the present disclosure, the WVT region may be defined at a first end of the substrate with the AA region being defined across the remainder of the substrate in the middle region extending to the second end of the substrate. Alternatively, with respect to all embodiments of the present disclosure, the WVT region may be defined at the first end of the substrate and at a second end of the substrate with the AA region disposed therebetween. It is understood that the membrane support layer implemented in all embodiments of the present disclosure, may but not necessarily, be formed from ePTFE (expanded polytetrafluoroethylene). Furthermore, in the embodiments having a WVT region which is defined at the first end and the second end with the AA region in between, the catalyst layer in the catalyst containing layer in the various embodiments may, but not necessarily extend into one of the two WVT regions (shown for example inFIG. 4) create a WVT region on either the first end or the second, or on both ends—first and second ends (FIG. 4). However, in doing so, the catalyst in one of the catalyst containing layers (of either the coated substrate or the companion coated substrate) must be removed so that the WVT region has, at most, one catalyst layer between the coated substrate and the catalyst coated substrate.

With reference to the first embodiment, the catalyst-containing layer may be coated using a single catalyst solution applied solely to the AA region. Therefore, the AA region of the coated substrate includes a substrate layer, the microporous layer, the catalyst layer, the first membrane ionomer layer, the optional membrane support layer, and the optional second membrane ionomer layer. Moreover, the WVT region of the coated substrate includes the substrate layer, the microporous layer, the first membrane ionomer layer, the optional membrane support layer, and the optional second membrane ionomer layer.

Alternatively, the catalyst-containing layer may be stripe-coated such that a catalyst layer is applied solely to the AA region and a mixed carbon/ionomer layer is optionally applied to the WVT region. Therefore, where the catalyst layer is stripe-coated, the WVT region of the coated substrate may include the substrate layer, the microporous layer, a mixed carbon/ionomer layer, the first membrane ionomer layer, the optional membrane support layer, and the optional second membrane ionomer layer.

In yet another embodiment of the present disclosure, the method for manufacturing an integrated MEA may include the steps of: (1) providing a substrate having an AA region and a WVT region; (2) coating a microporous layer across the substrate; (3) simultaneously coating a catalyst layer onto the microporous layer in the AA region and a first membrane ionomer layer in both the AA and WVT regions; (4) applying an optional membrane support layer to the first membrane ionomer layer in the AA region and the WVT region; (5) coating the optional second membrane ionomer layer onto the membrane support layer thereby forming a coated substrate; and (6) assembling the coated substrate to a companion coated substrate. The coated substrate may be heat-treated before assembling the coated substrate to a companion coated substrate.

In this embodiment, the AA region of the coated substrate may include the substrate layer, the microporous layer, the catalyst layer, the first membrane ionomer layer, the optional membrane support layer, and the optional second membrane ionomer layer. The WVT region of the coated substrate may include the substrate layer, the microporous layer, the optional carbon/ionomer layer, the first membrane ionomer layer, the optional membrane support layer, and the optional second membrane ionomer layer. In this embodiment, a die-coating tool may also be implemented to apply or coat the catalyst layer, and the first membrane ionomer layer simultaneously onto the substrate wherein the substrate is a gas diffusion media.

In yet another embodiment of the present disclosure, a method for manufacturing an integrated MEA may include the steps of: (1) providing a substrate having an AA region and a WVT region; (2) simultaneously applying a stripe-coated microporous layer, a stripe-coated catalyst-containing layer, and a stripe-coated first membrane ionomer layer onto the AA region and WVT region of the substrate; (3) applying an optional membrane support layer onto the first membrane ionomer layer across the AA region and the WVT region; (4) stripe coating the optional second membrane ionomer layer onto the membrane support layer thereby forming a coated substrate; and (5) assembling the coated substrate to a companion coated substrate. In this embodiment, the microporous layer is hydrophobic in the AA region and hydrophilic in the WVT region while the catalyst-containing layer includes a catalyst solely in the AA region and an optional mixed carbon/ionomer layer in the WVT region. The first membrane ionomer layer includes the first fuel cell membrane ionomer layer in the AA region and an optional WVT membrane ionomer in the MT region. The second membrane ionomer layer includes a second fuel cell membrane ionomer layer in the AA and an optional WVT membrane ionomer in the WVT region.

In this embodiment, the AA region of the coated substrate includes a substrate layer, the hydrophobic microporous layer, the catalyst layer, the first fuel cell membrane ionomer layer, the optional membrane support layer, and the optional second fuel cell membrane ionomer layer. The WVT region of the coated substrate includes a substrate layer, a hydrophilic microporous layer, the optional mixed carbon/ionomer layer, the optional first WVT membrane ionomer layer, the optional membrane support layer, and the optional second WVT membrane ionomer layer.

In yet another embodiment of the present disclosure, a method for manufacturing an integrated MEA includes the steps of: (1) providing a substrate having an AA region and a MT region; (2) providing a stripe-coated microporous layer onto the substrate in the AA region and the WVT region; (3) simultaneously coating a stripe-coated catalyst-containing layer, and a stripe-coated first membrane ionomer layer onto the AA region and MT region; (4) applying an optional membrane support layer onto the stripe-coated first membrane ionomer layer; (5) applying an optional stripe-coated second membrane ionomer layer onto the membrane support layer thereby forming a coated substrate; and (6) heat treating the coated substrate formed by the substrate and a plurality of layers; and (7) assembling the coated substrate to a companion coated substrate. The microporous layer is hydrophobic in the AA region and hydrophilic in the WVT region while the catalyst-containing layer includes a catalyst solution solely applied to form a layer in the AA region and an optional mixed carbon/ionomer layer solely applied to the WVT region. The first stripe-coated membrane ionomer layer of this embodiment includes a first fuel cell membrane ionomer solution in the AA region and an optional first WVT membrane ionomer solution applied in the WVT region. The second stripe-coated membrane ionomer layer includes a second fuel cell membrane ionomer solution applied in the AA region and a second optional WVT membrane ionomer solution applied in the WVT region.

In this embodiment, the AA region of the coated substrate includes the substrate layer, a hydrophobic microporous layer, a catalyst layer, a first fuel cell membrane ionomer layer, the optional membrane support layer, and an optional second fuel cell membrane ionomer. The WVT region of the coated substrate includes the substrate layer, the hydrophilic microporous layer, the mixed carbon/ionomer layer, the first ionomer layer (or the optional first WVT membrane ionomer layer), the optional membrane support layer, and the optional second WVT membrane ionomer layer.

The present disclosure and its particular features and advantages will become more apparent from the following detailed description considered with reference to the accompanying drawings.

DETAILED DESCRIPTION

Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present disclosure, which constitute the best modes of practicing the present disclosure presently known to the inventors. The figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the present disclosure that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the present disclosure and/or as a representative basis for teaching one skilled in the art to variously employ the present disclosure.

It is also to be understood that this present disclosure is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present disclosure and is not intended to be limiting in any way.

The terms “comprising”, “consisting of”, and “consisting essentially of” can be alternatively used. Where one of these three terms is used, the presently disclosed and claimed subject matter can include the use of either of the other two terms.

FIG. 1shows a schematic cathode subsystem of a fuel cell system110known in the art. As shown, the typical water vapor transfer (WVT) device104is located away from a cathode outlet130and a cathode inlet128of the fuel cell stack of the fuel cell stack system. The traditional fuel cell system may, but not necessarily, include a charge air cooler (CAC) and/or diverter112together with the water vapor transfer device104(such as a humidifier) to regulate a relative humidity of the fuel cell102. The charge air cooler and/or diverter112may have the first inlet132, the first outlet124, and the second outlet122. The traditional fuel cell system may further include the fuel cell102and an air compressor126as shown. The fuel cell102has a plurality of fuel cells, a cathode inlet128, and a cathode outlet130. The air compressor126is in fluid communication with the fuel cell102and adapted to provide a flow of charged air thereto. The WVT device104is generally an external component to the fuel cell stack and the WVT device104is in fluid communication with the air compressor126and the fuel cell102as shown. The WVT device104is adapted to selectively humidify the charged air provided to the fuel cell102. The WVT device104may transfer moisture to the input charged air127(coming from the compressor126) from the moist cathode exhaust stream148exiting the cathode outlet130via a membrane (not shown). Thus, the output charged air127′ from the WVT device has sufficient humidity for use in the fuel cell102. Other suitable means for humidifying the charged air may also be employed.

The optional charge air cooler (and/or diverter)112is disposed in communication with the air compressor126and each of the fuel cell102and the WVT device104. The first inlet132is in fluid communication with the air compressor126. The first outlet124is in fluid communication with the fuel cell102. The air compressor126draws in ambient air100and is in fluid communication with the WVT device104(via optional CAC and/or diverter112). The second outlet122is in fluid communication with the WVT device104. The charge air cooler (and/or three-way diverter) shown as element112is adapted to: a) cause charged air to bypass the WVT device104and flow to the fuel cell102; and/or b) cause charged air to flow to the WVT device104—to regulate the humidity of the fuel cell102.

The example known fuel system ofFIG. 1may include the actuator116, the controller118, and at least one humidity sensor120. The fuel cell system controller118may be in electrical communication with the actuator116. The controller118regulates the humidity of the fuel cell102via actuator and/or WVT. A humidity sensor120may be provided in electrical communication with the controller in order to provide feedback of the charged air relative humidity to the controller118. However, it is noted that more commonly known fuel cell systems eliminate the use of humidity sensors and instead use the high frequency (i.e. membrane) resistance of the stack to indirectly measure the moisture in the system. Nonetheless, regardless of whether humidity sensors are implemented, many fuel cell systems generally implement an external WVT device104as shown which requires space and thus increases the overall size of the fuel cell system. Packaging space for a fuel cell system can be particularly restrictive in applications such as, but not limited to vehicles. Thus, it is desirable to reduce the volume of such fuel cell systems especially in vehicle applications.

FIG. 2shows a more detailed schematic of a traditional fuel cell and external water vapor transfer device. Input charged air127from the compressor126(and/or optionally CAC & Diverter112) enters the WVT device104. The WVT membrane150is configured to transfer moisture158from the moist cathode exhaust gas stream148thereby creating humidified output charged air127′ to enter the fuel cell102at the cathode inlet128(seeFIG. 1). The cathode exhaust stream148exits the fuel cell102as moisture rich air due to the water byproduct156from the reaction on the MEA152in the fuel cell102. It is understood that after passing through the WVT device104, the cathode exhaust stream148′ has a reduced moisture content.

Accordingly, with reference toFIG. 3, the present disclosure provides an integrated fuel cell10having a WVT region which is internal to the fuel cell. The fuel cell10of the present disclosure includes a water transfer portion12which is integrated in the membrane electrode assembly18. The integrated fuel cell10includes a first bipolar plate14, a second bipolar plate16, and a membrane electrode assembly (MEA)18disposed between the first and second bipolar plates14,16as shown inFIG. 3. With reference toFIGS. 3-5, the membrane electrode assembly18further includes a water vapor transfer portion12and an active area portion20configured to generate electricity62and provide a water byproduct22upon facilitating a reaction involving an input stream with hydrogen24and input airstream26with oxygen. It is understood that all references to input airstream26should be interpreted to mean that input airstream26contains oxygen.

Referring again toFIG. 3, at first MEA end40, the water vapor transfer portion12of the membrane electrode assembly18may be hydrophilic relative to the active area portion20and is operatively configured to transfer moisture32from a primary stream25of fluid with higher relative humidity (such as but not limited output hydrogen stream24′) to a secondary stream23of fluid (such as but not limited to an input charged air stream26at first MEA end28). Alternatively, water vapor transfer portion12at the second MEA end30may be configured to also transfer moisture38from a primary stream25of fluid (exhaust airstream26′) to a secondary stream23of fluid (input gaseous stream with hydrogen24). It is understood that the primary stream25of fluid (exhaust airstream26′ or output hydrogen stream24′ or the like) is rich in moisture given that a water vapor byproduct32,38results when the fuel cell generates electricity.

Referring now toFIG. 6A, the present disclosure provides a first method for manufacturing an integrated MEA18which includes the following steps: (1) providing a substrate70having an AA region20and a WVT region12; (2) simultaneously coating89a microporous layer72, a catalyst layer74(either anode or cathode) onto the AA region20, and a first membrane ionomer layer76onto the substrate70; (3) applying an optional membrane support layer78to the first membrane ionomer layer76in the AA region20and the WVT region12; (4) coating an optional second membrane ionomer layer80onto the membrane support layer78(or onto the first membrane ionomer layer76if the membrane support layer78is omitted); (5) heat treating the coated substrate84formed by the substrate70and the aforementioned plurality of layers79applied to the substrate70; and (6) assembling the coated substrate84to a companion coated substrate85. The companion coated substrate85is shown inFIG. 6C. However, it is understood that the catalyst-containing layer74ofFIG. 6Amay alternatively be stripe-coatedstripe-coated (as part of the simultaneous coating step) such that an AA catalyst layer71is applied solely to the AA region20and a mixed carbon/ionomer solution73is applied to the WVT region12of the microporous layer72.

Therefore, it is understood that the coated substrate84may be formed upon applying the first membrane ionomer layer76as the final layer for the coated substrate84. However, as another option, the membrane support layer78may optionally be applied to the first membrane ionomer layer76as the final layer thereby forming a coated substrate84. Also, in yet a third option, the second membrane ionomer layer80may be applied as the final layer on top of the membrane support layer78thereby forming a coated substrate84. In a fourth option, the second membrane ionomer layer80may be applied directly to the first membrane ionomer layer76as the final layer to the coated substrate84—wherein the membrane support layer78would be omitted. The coated substrate84formed by the substrate70and a plurality of layers79(identified above) may then be heat treated and assembled to the companion coated substrate85(FIG. 6C).

As indicated, in the first aforementioned arrangement, the coated substrate84may be formed upon applying the first membrane ionomer76. Under this arrangement, the first membrane ionomer layer76may include a reinforcement material such as, but not limited to short plastic or ceramic fibers. The short plastic and/or ceramic fibers may be mixed into the first membrane ionomer solution and sent through die coating tool in order to apply the first membrane ionomer layer76having such fibers/reinforcement material.

With respect to all embodiments of the present disclosure, the coated substrate84may be heat-treated before assembling the coated substrate84to a companion coated substrate85. (FIG. 6C). A die coating tool86(FIG. 8) may be implemented to apply or coat the microporous layer72, the catalyst-containing layer74, and the first membrane ionomer layer76simultaneously onto the substrate70wherein the substrate70is a gas diffusion media. Moreover, with respect to all embodiments of the present disclosure, the WVT region12may be defined at a first end28of the substrate70with the AA region20being defined across the remainder of the substrate70in the middle region extending to the second end30of the substrate70as shown inFIG. 5. Alternatively, with respect to all embodiments of the present disclosure, the WVT region12may be defined at the first end28of the substrate70and at a second end30of the substrate70with the AA region20disposed therebetween as shown inFIG. 4. It is understood that the membrane support layer78implemented in all embodiments of the present disclosure, may but not necessarily, consist of expandedpolytetrafluoroethylene (ePTFE). Furthermore, in all of the embodiments having a WVT region12which is defined at both the first end28and the second end30with the AA region20in between, the catalyst layer71in the various embodiments may, but not necessarily, extend into one of the two WVT regions12(or may not extend into either of the WVT regions12at all).

Moreover, with respect to all embodiments in the present disclosure, each coated layer may be applied via a die coating process wherein each layer (except for the membrane support layer78) may be coated onto the substrate70. As previously indicated, the membrane support layer78may, but not necessarily, be an ePTFE material. Moreover, with respect to all embodiments of the present disclosure, each coated layer which is coated onto the substrate70may, but not necessarily, be heat-treated before the next layer is applied. In the present disclosure, the various embodiments refer to a microporous layer which should be construed to include, but not be limited to, a mixture of carbon black and a polymer binder in an alcohol/water solution that is coated and heat-treated. The term “alcohol/water solution” should be further construed to mean a solution which may have a content mixture which ranges from 100% alcohol and 0% to a solution having 0% alcohol and 100% water. Hydrophobic microporous layers may use a hydrophobic binder such as polytetrafluoroethylene. Hydrophilic microporous layers may use a hydrophilic binder such as an ionomer. Moreover, the present disclosure's reference to an “ionomer” should be construed to include, but not be limited to, a perfluorosulfonic acid. It is understood that the “ionomer layer” is perfluorosulfonic acid coated from an alcohol/water solution. The equivalent weight (EW) is a measure of the concentration of sulfonic acid sites with lower EW meaning high concentration of sulfonic acid sites.

Moreover, the present disclosure's reference to a “catalyst layer” should be construed to include, but not be limited to mixtures of Pt-based nanoparticles supported on electronically conductive supports (e.g. carbon) and an ionomer binder coated from an alcohol/water solution which is heat-treated to form the layer. References to a “carbon/ionomer layer” should be construed to include, but not be limited to mixtures of electronically conductive supports (e.g. carbon) and ionomer binder coated from an alcohol/water solution which is heat-treated to form the layer. Additionally, references to a “fuel cell membrane ionomer and WVT ionomer” should be construed to include but not be limited to meaning that the WVT ionomer would have a lower EW (higher concentration of sulfonic acid) than the fuel cell ionomer.

References to a “gas diffusion media” should be construed to include but not be limited to a carbon-fiber-based paper, bound chemically (e.g. with a resin binder) or mechanically (e.g. hydroentangled). Upon coating the gas diffusion media with the microporous layer, the combination of these elements may constitute the gas diffusion layer. Moreover, references to “short ceramic or plastic fibers” should be construed to include but not be limited to fibers which may have diameters of <1 micron and aspect ratio (length/diameter) of greater than 10.

With reference toFIGS. 6A and 6B, the catalyst-containing layer74may be coated to form a single AA catalyst layer71applied solely to the AA region20. Alternatively, the catalyst-containing layer74may be stripe-coated stripe-coated wherein a single AA catalyst layer71is applied only in the AA while an optional mixed carbon-ionomer layer is applied in the WVT region12. Therefore, the AA region20of the coated substrate84may include a substrate70layer, the microporous layer72, the catalyst layer74, the first membrane ionomer layer76, the optional membrane support layer78, and the optional second membrane ionomer80. However, the WVT region12of the coated substrate84may include the substrate70layer, the microporous layer72, the first membrane ionomer layer76, the optional membrane support layer78, and the optional second membrane ionomer80. In the alternative, the WVT region12of the coated substrate84may include the substrate70layer, the microporous layer72, the first membrane ionomer layer76, the optional mixed carbon ionomer layer73, the optional membrane support layer78, and/or the optional second membrane ionomer80. It is understood that all layers shown in phantom are optional layers which may or may not be included. Moreover, any combination of the optional layers may be used.

Referring now toFIG. 6B, a second embodiment of the present disclosure is provided wherein a method for manufacturing an integrated fuel-cell/WVT-region MEA may include the steps of: (1) providing a substrate70having an AA region20and a WVT region12; (2) coating a microporous layer72across the substrate70; (3) simultaneously coating89′ a catalyst-containing layer74and a first membrane ionomer layer76onto the microporous layer72; (4) applying an optional membrane support layer78to the first membrane ionomer layer76; (5) optionally applying a second membrane ionomer layer80onto the membrane support layer78(or onto the first membrane ionomer layer76if the membrane support layer78is omitted); (6) heat treating the coated substrate84′ formed by the substrate70and the aforementioned plurality of layers79applied to the substrate70; and (7) assembling the coated substrate84′ to a companion coated substrate85. It is understood that the catalyst-containing layer74is applied onto the microporous layer72in the AA region20as shown. However, it is understood that the catalyst-containing layer74ofFIG. 6Bmay alternatively be stripe-coatedstripe-coated (as part of the simultaneous coating step89′) such that an AA catalyst layer71is applied solely to the AA region20and a mixed carbon/ionomer layer73is applied to the WVT region12of the microporous layer72as shown inFIG. 6B. The coated substrate84′ may then be heat-treated before assembling the coated substrate84′ to a companion coated substrate85(shown inFIG. 6C). A die coating tool86may be implemented to apply or coat the catalyst-containing layer74(which may or may not be stripe-coated as indicated above), and the first membrane ionomer layer76simultaneously onto the substrate70wherein the substrate70is a gas diffusion media.

Therefore, it is understood that the coated substrate84′ ofFIG. 6Bmay be formed upon applying the first membrane ionomer layer76as the final layer to the coated substrate84′. However, as another option, the membrane support layer78may optionally be applied to the first membrane ionomer layer76as the final layer thereby forming the coated substrate84′. Also, in yet a third option, the second membrane ionomer layer80may be applied on top of the membrane support layer78as the final layer thereby forming a coated substrate84′. In a fourth option, the second membrane ionomer layer80may be applied directly to the first membrane ionomer layer76thereby forming the coated substrate. Thus, the coated substrate84′ may be formed by the substrate70and any combination of the plurality of layers79(identified above) which will then be heat treated and assembled to the companion coated substrate85. The companion coated substrate85for the coated substrate84,84′ also includes a substrate70(FIG. 6C), a microporous layer72, and a catalyst layer74. Similar to the coated substrate84,84′ ofFIGS. 6A and 6B, the catalyst-containing layer74of the companion coated substrate85may or may not be stripe-coatedstripe-coated as shown inFIG. 6C.

In the first aforementioned arrangement, the coated substrate84′ may be formed upon applying the first membrane ionomer layer76as the final layer in the simultaneous coating step89′. Under this arrangement, the first membrane ionomer layer76ofFIG. 6Bmay include a reinforcement material such as, but not limited to, short plastic or ceramic fibers. The short plastic and/or ceramic fibers may be mixed into the first membrane ionomer solution which is then sent through a die coating tool to apply the first membrane ionomer layer76.

In the second embodiment ofFIG. 6B, the AA region20of the coated substrate84′ may include the substrate70layer, the microporous layer72, the catalyst-containing layer74, the first membrane ionomer layer76, the optional membrane support layer78, and the optional second membrane ionomer80. The WVT region12of the coated substrate84′ may include the substrate70layer, the microporous layer72, an optional mixed carbon-ionomer layer73, the first membrane ionomer layer76, the optional membrane support layer78, and the optional second membrane ionomer layer80.

Referring now toFIG. 7A, the third embodiment of the present disclosure is provided wherein the method for manufacturing an integrated fuel-cell/WVT-region MEA18(FIG. 4) may include the steps of: (1) providing a substrate70′ having an AA region20and a WVT region12; (2) simultaneously applying 89″ a stripe-coated microporous layer (MPL)72′, a catalyst-containing layer74′ (which may or may not be stripe-coated), and a first membrane ionomer layer76′ (which may or may not be stripe-coated) onto the substrate70′; (3) applying an optional membrane support layer78′ onto the first membrane ionomer layer76′; (4) optionally applying a second membrane ionomer layer80′ (which may or may not be stripe-coated) thereby forming a coated substrate84″; and (5) assembling the coated substrate84″ to a companion coated substrate85′ (FIG. 7C). In this third embodiment ofFIG. 7A, the stripe-coated microporous layer72′ may be hydrophobic69′ in the AA region20and hydrophilic67′ in the WVT region12while the catalyst-containing layer74′ includes a catalyst layer71′ which is solely disposed in the AA region20and may or may not include a mixed carbon/ionomer layer73′ solely disposed in the WVT region(s)12. The first membrane ionomer layer76′ (which may or may not be stripe-coated) may include the first fuel cell membrane ionomer layer75′ in the AA region20and optionally a first WVT membrane ionomer layer77′ in the MT region12as shown inFIG. 7A. The optional second membrane ionomer layer80′ may include a second fuel cell membrane ionomer layer79′ in the AA region and an optional second WVT membrane ionomer layer81′ in the WVT region12. Accordingly, it is understood that certain layers such as the optional second membrane ionomer layer80′ may or may not be stripe-coated depending upon whether the optional solution (ex: WVT membrane ionomer) is applied in the MT region.

Therefore, it is understood that the coated substrate84″ may be formed upon applying the first membrane ionomer layer76′ which may or may not be stripe-coated as shown inFIG. 7A. However, as another option, the membrane support layer78′ may optionally be applied to the first membrane ionomer layer76′ (which may or may not be stripe-coated) thereby forming a coated substrate84″. Also, in yet a third option, the second membrane ionomer layer80′ (which may or may not be stripe-coated) may be applied on top of the membrane support layer78′ as the final layer thereby forming a coated substrate84″. In a fourth option, the second membrane ionomer layer80′ may be applied directly to the first membrane ionomer layer76′. The coated substrate84″ formed by the substrate70′ and a plurality of layers (identified above)79′ may then be heat treated and assembled to the companion coated substrate85′. As shown inFIG. 7C, the companion coated substrate85′ for coated substrate84″,84′″ ofFIGS. 7A and 7Balso includes a substrate70′, a microporous layer72′ which may or may not be stripe-coated as shown, and a catalyst-containing layer74′ which also may or may not be stripe-coated as explained above for the coated substrate84″ (and below for the coated substrate84′″).

As indicated, in the first aforementioned arrangement for the third embodiment, the coated substrate84″ may be formed upon applying the first membrane ionomer layer76′. Under this arrangement, the first membrane ionomer layer76′ may include reinforcement material such as, but not limited to, short plastic or ceramic fibers. The short plastic and/or ceramic fibers may be mixed into the first membrane ionomer solution76′ and sent through a die-coating tool to apply the first membrane ionomer layer76′.

In the embodiment shown inFIG. 7A, the AA region20of the coated substrate84″ includes a substrate70′ layer, the hydrophobic MPL69′, the catalyst layer71′, the first fuel cell membrane ionomer layer75′, the optional membrane support layer78′, and the optional second fuel cell membrane ionomer layer80′. The WVT region12of the coated substrate84″ may include a substrate70′ layer, the optional hydrophilic MPL67′, an optional mixed carbon/ionomer layer73′, the first membrane ionomer layer with optional WVT membrane ionomer layer77′, the optional membrane support layer78′, and the optional second WVT membrane ionomer layer81′. With reference toFIG. 7A, it is understood that the optional mixed carbon/ionomer layer73′ may be disposed in the WVT region12when the catalyst-containing layer74′ is stripe-coated to the stripe-coated microporous layer72′.

Referring now toFIG. 7B, fourth embodiment of the present disclosure includes a method for manufacturing an integrated fuel-cell/WVT-region MEA84′″ includes the steps of: (1) providing a substrate70′ having an AA region20and a WVT region12; (2) providing a stripe-coated microporous layer72′ onto the substrate70′ in the AA region20and the WVT region12; (3) simultaneously applying 89′″ a catalyst-containing layer74′, and a first membrane ionomer layer76′; (4) applying an optional membrane support layer78′ onto the coated membrane ionomer layer76′; (5) optionally coating the second membrane ionomer layer80′ onto the membrane support layer78′ (or onto the first stripe-coated membrane ionomer layer76′ if the membrane support layer78′ is omitted); (6) heat treating the coated substrate84′″ formed by the substrate70′ and the aforementioned plurality of layers79′ applied to the substrate70′; and (7) assembling the coated substrate84′″ to a companion coated substrate85′, The aforementioned stripe-coated microporous layer72′ may arranged such that a hydrophobic MPL69′ is disposed in the AA region20and a hydrophilic MPL67′ is disposed in the MT region12. Similarly, the catalyst-containing layer74′ may include a catalyst layer71′ solely applied to the AA region20and the optional mixed carbon/ionomer layer73′ solely applied to the WVT region12such that the catalyst-containing layer74is stripe-coated during the simultaneous coating step89′″. As indicated, the first membrane ionomer layer76′ of this embodiment may be stripe-coated such that a first fuel cell membrane ionomer layer75′ is applied to the AA region20and a first WVT membrane ionomer layer77′ is applied in the WVT region12. Similarly, the second membrane ionomer layer80′ may optionally be stripe-coated such that a second membrane ionomer layer82′ is applied to the AA region20and a second WVT membrane ionomer layer81′ is applied to the WVT region12when the simultaneous coating step89″ occurs.

Therefore, it is understood that the coated substrate84′″ may be formed upon applying the first membrane ionomer layer76′ given that the membrane support layer78′ is optional. Moreover, the stripe-coated microporous layer72′ may be hydrophobic69′ in the AA region20and hydrophilic67′ in the WVT region12while the catalyst-containing layer74′ includes a catalyst layer71′ which is solely disposed in the AA region20and may or may not include a mixed carbon/ionomer layer73′ solely disposed in the WVT region(s)12. The first membrane ionomer layer76′ (which may or may not be stripe-coated) may include the first membrane ionomer layer75′ in the AA region20and optionally a first WVT membrane ionomer layer77′ in the WVT region12as shown inFIG. 7B. The optional second membrane ionomer layer80′ may include a second fuel cell membrane ionomer layer82′ in the AA region and an optional second WVT membrane ionomer layer81′ in the WVT region12. Accordingly, it is understood that certain layers such as the optional second membrane ionomer layer80′ may or may not be stripe-coated depending upon whether the optional solution (ex: WVT membrane ionomer) is applied in the WVT region.

In one option for the coated substrate84′″ ofFIG. 7B, the membrane support layer78′ may optionally be applied to the first membrane ionomer layer76′ as the final layer for the coated substrate84′″. However, in a second option, the second membrane ionomer layer80′ may be applied on top of the membrane support layer78′ thereby forming a coated substrate84′″. In a third option, the second membrane ionomer layer80′ may be applied directly to the first membrane ionomer layer76′. Again, it is understood that layers74′,76′,80′ may or may not be stripe-coated. The coated substrate84′″ formed by the substrate70′ and any combination of the plurality of layers79′ (as described above) may then be heat treated and assembled to the companion coated substrate85′.

In the first aforementioned arrangement, the coated substrate84′″ may be formed upon applying the first stripe-coated membrane ionomer layer76′ as the final layer for the coated substrate85′. Under this arrangement, the first membrane ionomer layer76′ may include a reinforcement material such as, but not limited to, short plastic or ceramic fibers. The short plastic and/or ceramic fibers may be mixed into the first membrane ionomer solution which is then sent through die-coating tool in order to apply the first membrane ionomer layer76′.

In the fourth embodiment shown inFIG. 7B, the AA region20of the coated substrate84′″ includes a substrate layer70′, the hydrophobic microporous layer69′, the catalyst layer71′, the first fuel cell membrane ionomer layer75′, the optional membrane support layer78′, and the optional second fuel cell membrane ionomer82′. The WVT region12of the coated substrate84′″ may include the substrate layer70′, the hydrophilic MPL67′, the optional mixed carbon/ionomer layer73′, the optional first WVT membrane ionomer layer77′, the optional membrane support layer78′, and the optional second WVT membrane ionomer layer81′.

With reference toFIG. 8, the stripe coating step of the various embodiments is shown wherein a die coating tool86accepts WVT solution88as well as AA solution90. WVT solution88may be any of the aforementioned solutions/layers which are dedicated to the WVT region12′ of the substrate roll83during a stripe-coating step (or WVT region12of the coated substrate). In doing so, a particular layer may be stripe-coated. AA solution may be any of the aforementioned solutions/layers which are dedicated to the AA region20′ of the substrate roll83during a stripe-coating step (or AA region20of the coated substrate). As shown inFIG. 8, the die coating tool86is configured to distribute the aforementioned solutions to their dedicated regions as shown as the substrate roll83moves away from the die coating tool.

With reference toFIG. 9, an expanded view of an example cross-section of a WVT region12of an MEA18(along line9-9inFIG. 5) is shown wherein the MEA18is formed by assembling the companion coated substrate85to the coated substrate84. Similarly, with reference toFIG. 10, an expanded view of an example cross-section of an AA region20of an MEA18(along line10-10inFIG. 5) is shown wherein the MEA18is formed by assembling the companion coated substrate85to the coated substrate84. The AA region primarily differs from the WVT region at least by the fact that the AA region includes two catalyst layers. The proton exchange membrane73is a layer which is formed by the first and optional second membrane ionomer layers76,80(as described in all of the embodiments of the present disclosure) with the optional membrane support layer78disposed there between.