Membranes for electrochemical devices

Abstract

The invention relates to a membrane for an electrochemical device. The membrane electrode assembly includes an anode, a cathode adjacent the cathode gas diffusion layer, and a proton exchange membrane (PEM) separating the anode from the cathode. The PEM includes at least one gas recombination layer, at least one ionomer layer, and a reinforcement layer. Each enhancement layer includes a pair of opposing surfaces, wherein one of the at least one gas recombination layer or the at least one ionomer layer is adjacent to each of the pair of opposing surfaces.

Description

Technical Field

[0001] The present disclosure generally relates to electrochemical systems, such as fuel cells for converting hydrogen-rich fuels into electricity or electrolyzers for converting water into hydrogen and oxygen. More particularly, aspects of the present disclosure relate to membrane electrode assemblies for electrochemical systems. Background Art

[0002] An electrolyzer is an electrochemical device that uses electrolysis to convert water into hydrogen and oxygen. Electrolyzers are commonly used to produce hydrogen. Hydrogen is used in many industrial applications, such as ammonia production. Electrolyzers can be used for on-site hydrogen production, for example as fuel for vehicles equipped with hydrogen fuel cells. Electrolyzers can also be used to store energy from dynamic power sources such as wind turbines and solar cells.

[0003] Hybrid electric vehicles and all-electric vehicles employ rechargeable energy storage systems, such as high-voltage, high-energy density electric vehicle battery (EVB) systems or fuel cell systems (FCS), to provide the necessary electrical power to operate the (multiple) electric traction motors of the vehicle powertrain. According to the latter, a fuel cell is an electrochemical device that typically consists of an anode electrode that receives a supply of hydrogen (H 2 ), a cathode electrode that receives an oxidant (O 2 ), and an electrolyte barrier interposed between the anode and cathode electrodes. An electrochemical reaction is initiated to oxidize hydrogen molecules on the anode side of the FCS - the hydrogen gas is catalytically split in an oxidation half-cell reaction - to produce free electrons (-) and free protons (H + ). The free hydrogen protons cross the electrolyte barrier to the cathode side of the cell, where these protons react with oxygen and electrons in the cathode to form various stack by-products, typically water and heat. However, the free electrons from the anode are prevented from crossing the electrolyte; these electrons are redirected to a load, such as the traction motor and accessories of the vehicle, and are subsequently received at the cathode. Summary of the Invention

[0004] A membrane electrode assembly is disclosed in the present invention. The assembly includes an anode, a cathode adjacent to the cathode gas diffusion layer, and a proton exchange membrane (PEM) separating the anode from the cathode. The PEM includes at least one gas recombination layer, at least one ionomer layer, and a reinforcing layer. Each reinforcing layer includes a pair of opposing surfaces, wherein one of the at least one gas recombination layer or the at least one ionomer layer is adjacent to each of the pair of opposing surfaces.

[0005] Another aspect of the present disclosure may include an anode gas diffusion layer adjacent to the anode.

[0006] Another aspect of the present disclosure may include a porous transport layer adjacent to the anode and on a side of the anode opposite the PEM.

[0007] Another aspect of the present disclosure may be one in which one reinforcing layer separates at least one ionomer layer from at least one gas recombination layer.

[0008] Another aspect of the present disclosure may be one in which the reinforcing layer is composed of at least one of an ionomer-swelled woven matrix material or an ionomer-swelled nonwoven matrix material.

[0009] Another aspect of the present disclosure may be one in which the thickness, matrix, and material composition of each reinforcing layer are different.

[0010] Another aspect of the present disclosure may be one in which the thickness, matrix, and material composition of each reinforcing layer are the same.

[0011] Another aspect of the present disclosure may be one in which at least one reinforcing layer is composed of expanded polytetrafluoroethylene (ePTFE).

[0012] Another aspect of the present disclosure may be one in which at least one gas recombination layer includes an ionomer and at least one gas recombination catalyst.

[0013] Another aspect of the present disclosure may be one in which at least one gas recombination layer includes a plurality of gas recombination layers, each gas recombination layer having different thicknesses, uniformities, and compositions.

[0014] Another aspect of the present disclosure may be one in which at least one gas recombination layer includes a plurality of gas recombination layers, each gas recombination layer having the same thickness, uniformity, and composition.

[0015] Another aspect of the present disclosure may be one in which at least one gas recombination catalyst includes at least one of platinum or palladium, and at least one recombination catalyst is supported by at least one of C, SiO 2 , TiO 2 , CeO 2 , Nb 2 O 5 or IrO x among others.

[0016] Another aspect of the present disclosure may be one in which at least one gas recombination catalyst is uniformly distributed in at least one gas recombination layer.

[0017] Another aspect of the present disclosure may be one in which at least one gas recombination catalyst is non-uniformly distributed in at least one gas recombination layer.

[0018] Another aspect of the present disclosure may be one in which at least one gas recombination catalyst is distributed as at least one of particles, fibers, or flakes.

[0019] A proton exchange membrane is disclosed herein. The membrane includes at least one gas recombination layer, at least one ionomer layer, and a reinforcing layer. Each reinforcing layer includes a pair of opposing surfaces, wherein one of the at least one gas recombination layer or the at least one ionomer layer is adjacent to each of the pair of opposing surfaces.

[0020] A vehicle is disclosed herein. The vehicle includes a vehicle body, wheels supporting the vehicle body, an electric motor configured to drive the wheels, and a battery pack configured to supply power to the electric motor. The vehicle further includes a fuel cell configured to supply power to at least one of the battery pack or the electric motor. The fuel cell includes an anode, a cathode adjacent to a cathode gas diffusion layer, and a proton exchange membrane (PEM) separating the anode from the cathode. The PEM includes at least one gas recombination layer, at least one ionomer layer, and a reinforcing layer. Each reinforcing layer includes a pair of opposing surfaces, wherein one of the at least one gas recombination layer or the at least one ionomer layer is adjacent to each of the pair of opposing surfaces.

[0021] The present invention discloses the following solutions:

[0022] Solution 1. A membrane electrode assembly, comprising:

[0023] An anode;

[0024] A cathode adjacent to a cathode gas diffusion layer; and

[0025] A proton exchange membrane (PEM) separating the anode from the cathode; wherein the PEM comprises:

[0026] At least one gas recombination layer;

[0027] At least one ionomer layer; and

[0028] A plurality of reinforcing layers, each reinforcing layer having a pair of opposing surfaces, wherein one of the at least one gas recombination layer or the at least one ionomer layer is adjacent to each of the pair of opposing surfaces.

[0029] Solution 2. The assembly according to Solution 1, comprising an anode gas diffusion layer adjacent to the anode.

[0030] Solution 3. The assembly according to Solution 1, comprising a porous transport layer adjacent to the anode and on a side of the anode opposite to the PEM.

[0031] Solution 4. The assembly according to Solution 1, wherein one of the plurality of reinforcing layers separates the at least one ionomer layer from the at least one gas recombination layer.

[0032] Aspect 5. The assembly according to Aspect 1, wherein the plurality of reinforcing layers consists of at least one of an ionomer-swollen woven matrix material or an ionomer-swollen non-woven matrix material.

[0033] Aspect 6. The assembly according to Aspect 5, wherein each of the plurality of reinforcing layers has a different thickness, matrix, and material composition.

[0034] Aspect 7. The assembly according to Aspect 5, wherein each of the plurality of reinforcing layers has the same thickness, matrix, and material composition.

[0035] Aspect 8. The assembly according to Aspect 5, wherein at least one of the plurality of reinforcing layers consists of expanded polytetrafluoroethylene (ePTFE).

[0036] Aspect 9. The assembly according to Aspect 1, wherein the at least one gas reforming layer comprises an ionomer having at least one gas reforming catalyst.

[0037] Aspect 10. The assembly according to Aspect 9, wherein the at least one gas reforming layer comprises a plurality of gas reforming layers, each of the plurality of gas reforming layers having a different thickness, uniformity, and composition.

[0038] Aspect 11. The assembly according to Aspect 9, wherein the at least one gas reforming layer comprises a plurality of gas reforming layers, each of the plurality of gas reforming layers having the same thickness, uniformity, and composition.

[0039] Aspect 12. The assembly according to Aspect 9, wherein the at least one gas reforming catalyst comprises at least one of platinum or palladium, and at least one reforming catalyst is supported by at least one of C, SiO 2 , TiO 2 , CeO 2 , Nb 2 O 5 or IrO x .

[0040] Aspect 13. The assembly according to Aspect 9, wherein the at least one gas reforming catalyst is uniformly distributed in at least one of the plurality of gas reforming layers.

[0041] Aspect 14. The assembly according to Aspect 9, wherein the at least one gas reforming catalyst is non-uniformly distributed in at least one gas reforming layer.

[0042] Aspect 15. The assembly according to Aspect 9, wherein the at least one gas reforming catalyst is distributed as at least one of particles, fibers, or flakes.

[0043] Scheme 16. A proton exchange membrane, comprising:

[0044] At least one gas recombination layer;

[0045] At least one ionomer layer; and

[0046] A plurality of reinforcing layers, each reinforcing layer comprising a pair of opposing surfaces, wherein one of the at least one gas recombination layer or the at least one ionomer layer is adjacent to each of the opposing surfaces of the pair.

[0047] Scheme 17. The proton exchange membrane according to Scheme 16, wherein one of the plurality of reinforcing layers separates the at least one ionomer layer from the at least one gas recombination layer, and at least one of the plurality of reinforcing layers is composed of expanded polytetrafluoroethylene (ePTFE).

[0048] Scheme 18. The proton exchange membrane according to Scheme 16, wherein the plurality of reinforcing layers is composed of at least one of an ionomer-swollen woven matrix material or an ionomer-swollen non-woven matrix material.

[0049] Scheme 19. The proton exchange membrane according to Scheme 16, wherein the at least one gas recombination layer comprises an ionomer containing at least one of platinum or palladium, and at least one recombination catalyst is supported by at least one of C, SiO 2 , TiO 2 , CeO 2 , Nb 2 O 5 or IrO x .

[0050] Scheme 20. A vehicle, comprising:

[0051] A vehicle body defining a passenger compartment;

[0052] A plurality of wheels supporting the vehicle body;

[0053] An electric motor configured to drive the plurality of wheels; and

[0054] A fuel cell configured to supply power to the electric motor to drive the plurality of wheels, the fuel cell comprising:

[0055] An anode;

[0056] A cathode adjacent to a cathode gas diffusion layer; and

[0057] A proton exchange membrane (PEM) separating the anode from the cathode; wherein the PEM comprises:

[0058] At least one gas recombination layer;

[0059] At least one ionomer layer; and

[0060] Multiple reinforcing layers, each reinforcing layer including a pair of opposing surfaces, wherein one of the at least one gas recombination layer or the at least one ionomer layer is adjacent to each of the pair of opposing surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 is an elevation perspective view of a representative motor vehicle, wherein the inset schematically shows a rechargeable energy storage system containing a traction battery pack and a fuel cell system for operating one or more electric motors of an electrified powertrain in accordance with various aspects of the disclosed concepts.

[0062] Figure 2 is a schematic diagram of an electrolysis system in accordance with one or more embodiments of the present disclosure.

[0063] Figure 3 is Figure 2 a cross-sectional view of an exemplary cell stack in an electrolyzer of the electrolysis system of

[0064] Figure 4 shows an exemplary membrane electrode assembly for an Figure 2 electrolysis system of

[0065] Figure 5 shows an exemplary Figure 1 for a fuel cell system or Figure 2 an exemplary proton exchange membrane for an electrolysis system of

[0066] Figure 6 shows an exemplary Figure 1 for a fuel cell system or Figure 2 another exemplary proton exchange membrane for an electrolysis system of

[0067] Figure 7 shows an exemplary Figure 1 for a fuel cell system or Figure 2 yet another exemplary proton exchange membrane for an electrolysis system of

[0068] Figure 8 shows an exemplary Figure 1 for a fuel cell system or Figure 2 still another exemplary proton exchange membrane for an electrolysis system of

[0069] The present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments are shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the novel aspects of the present disclosure are not limited to the specific forms shown in the above-listed drawings. Instead, the present disclosure covers all modifications, equivalents, combinations, permutations, groupings, and alternatives that fall within the scope of the present disclosure as defined, for example, by the appended claims. DETAILED DESCRIPTION

[0070] The present disclosure admits many different forms of embodiments. Representative embodiments of the present disclosure are shown in the accompanying drawings and will be described in detail herein. It should be understood that these embodiments are provided as examples of the principles of the disclosure and not as limitations on the broad aspects of the present disclosure. In this regard, elements and limitations described, for example, in the abstract, introduction, overview, and detailed description sections but not expressly set forth in the claims should not be incorporated into the claims singly or jointly by implication, inference, or otherwise.

[0071] For the purposes of this detailed description, unless expressly disclaimed: the singular includes the plural and vice versa; the words "and" and "or" shall be both conjunctive and disjunctive; the words "any" and "all" shall each mean "any and all"; and the words "comprising", "having", "including", "containing", etc. shall each mean "including but not limited to". In addition, approximating words such as "about", "almost", "substantially", "generally", "approximately", etc. may each be used herein in the sense of, for example, "at, near, or approaching", or "within 0-5% of", or "within acceptable manufacturing tolerances", or any logical combination thereof. Finally, directional adjectives and adverbs such as front, rear, inner, outer, starboard, port, vertical, horizontal, upward, downward, forward, backward, left, right, etc. may be relative to a motor vehicle, such as the forward driving direction of a motor vehicle when the vehicle is operably oriented on a horizontal driving surface.

[0072] Reference is now made to the accompanying drawings, in which like reference numerals designate like features throughout the several views, Figure 1 in which a representative motor vehicle, generally designated 10, is shown and depicted herein for purposes of discussion as a sedan-type fuel cell electric vehicle (FCEV). The illustrated motor vehicle 10 - also referred to herein as a "motor vehicle" or simply a "vehicle" - is merely an exemplary application in which the novel aspects of the present disclosure may be practiced. Similarly, incorporating the concepts of the present invention into a fully electric powertrain should be understood as a non-limiting implementation of the disclosed features. Accordingly, it is to be understood that aspects and features of the present disclosure may be applied to other powertrain architectures, for various different fuel cell system configurations, and incorporated into any logically related type of vehicle. In addition, selected components of the motor vehicle, FCS, and manufacturing system are shown and described in more detail herein. However, the vehicles and systems discussed below may include many additional and alternative features, as well as other available peripheral components, for implementing the various methods and functions of the present disclosure.

[0073] Enclosed within the vehicle body 12 that defines the passenger compartment of the vehicle 10 is a representative fuel cell system 14 for powering a prime mover, such as an electric motor generator unit (MGU) 16, operable to drive a combination of vehicle wheels 18, an electrochemical system, such as Figure 1 a proton exchange membrane fuel cell system 14, equipped with one or more fuel cell stacks 20, each fuel cell stack being composed of a plurality of PEM type fuel cells 22, which are stacked and electrically connected in series or parallel with each other. In the illustrated architecture, each fuel cell 22 is a multi-layer construction having an anode side 24 and a cathode side 26 separated by a proton-conducting semi-permeable polymer membrane 28, an anode gas diffusion electrode (GDE) layer 30 being disposed on the anode side 24 of the PEMFC 22, and an anode catalyst layer 32 being mounted onto the GDE layer 30 or inserted and operatively connected to the membrane 28 and the corresponding GDE layer 30. Disposed in a relative spaced relationship with the anode layers 30 and 32 is a cathode gas diffusion electrode (GDE) layer 34, which is disposed on the cathode side 26 of the PEMFC 22. A cathode catalyst layer 36 is mounted onto this GDE layer 34, or inserted and operatively connected to the membrane 28 and the corresponding GDE layer 34. The two GDE layers 30 and 34, the two catalyst layers 32 and 36, and optionally subgaskets (see Figure 2 ) cooperate with the membrane 28 to integrally or partially define a membrane electrode assembly (MEA) 38.

[0074] The gas diffusion layers 30 and 34 can be a porous structure that provides fluid ingress transport to the MEA 38 and fluid egress transport from the MEA. An anode flow field plate 40 (with an optional bipolar plate) is disposed on the anode side 24 adjacent to the anode GDE layer 30. In the same manner, a cathode flow field plate 42 (with an optional bipolar plate) is disposed on the cathode side 26 adjacent to the cathode GDE layer 34. Coolant flow channels 44 traverse each of the plates 40 and 42 to allow a cooling fluid to flow through the fuel cells 22. Fluid inlets and manifolds direct the hydrogen-rich fuel and oxidant to the respective passages in the anode and cathode flow field plates 40, 42. The central active area of the anode flow field plate 40 facing the anode of the proton-conducting membrane 28 can be fabricated with an anode flow field consisting of serpentine flow channels to distribute hydrogen on the opposing faces of the GDE layer 30 and the membrane 28. The MEA 38 and the flow field plates 40, 42 can be stacked together between a current collector plate and a single end plate (not shown). The fuel cell system 14 can also employ anode recirculation, where anode recirculation gas is fed from an exhaust manifold or header through an anode recirculation line to recycle hydrogen back to the anode side 24 input to retain hydrogen gas in the stack 20.

[0075] Hydrogen (H 2)The inlet stream - whether gaseous, concentrated, entrained, or otherwise - is transferred from a hydrogen source (such as fuel storage tank 46) to the anode side 24 of the fuel cell stack 20 via a fluid injector 47 coupled to a (first) liquid inlet conduit or hose 48. Anode exhaust exits the stack 20 via a (first) liquid drain conduit or hose 50. A compressor or pump 52 is also shown at the inlet (left side) of the stack 20, which supplies a cathode inlet stream, such as ambient air and / or concentrated gaseous oxygen (O 2 ) to the cathode side 26 of the pair 20 via a (second) liquid inlet line or manifold 54. Cathode exhaust is output from the stack 20 via a (second) liquid drain conduit or manifold 56. Flow control valves, flow restrictors, filters, and other available devices for regulating fluid flow can be implemented by the Figure 1 PEMFC system 14. The electrical power generated by the fuel cell stack 20 and output by the fuel cell system 14 can be transferred for storage into an on-board traction battery pack 82 within a rechargeable energy storage system (RESS) 80.

[0076] Figure 1 The fuel cell system 14 of Figure 1 may also include a thermal subsystem that is operable to control the temperature of the fuel cell stack 20, for example, during pre-treatment, break-in, and post-treatment processes. According to the illustrated example, a coolant pump 58 pumps coolant fluid through a coolant loop 60 to the fuel cell stack 20 and into the coolant channels 44 within each cell 22. A radiator 62 and an optional heater 64, fluidly coupled in the coolant loop 60, are used to maintain the stack 20 at a desired operating temperature. The thermal subsystem can be equipped with various sensing devices for monitoring normal system operation as well as the progress of fuel cell treatment and break-in. For example, an inlet (first) temperature sensor 66 monitors the coolant temperature value at the coolant inlet of the fuel cell stack 20, and an outlet (second) temperature sensor 68 measures the coolant temperature value at the coolant outlet of the fuel cell stack 20. Electrical connectors or cables 74 connect the fuel cell stack 20 to an electrical load 76, which can be used to draw current from each cell 22 in the stack 20. A voltage / current sensor 70 is operable to measure, monitor, or otherwise detect the fuel cell voltage and / or current on the fuel cells 22 in the stack 20.

[0077] A programmable electronic control unit (ECU) 72 aids in controlling the operation of the fuel cell system 14. As an example, the ECU 72 receives one or more temperature signals T1 from one or more temperature sensors 66, 68 indicating the temperature of the fuel cell stack 20; the ECU 72 can be programmed to responsive issue one or more command signals C1 to adjust the operation of the stack 20. Figure 1The ECU 72 also receives one or more voltage signals V1 from the voltage / current sensor 70; the ECU 72 can be programmed to responsive issue one or more command signals C2 to adjust the operation of the hydrogen source (e.g., the fuel storage tank 46) and / or the compressor / pump 52, thereby regulating the electrical output of the stack 20. Figure 1 The ECU 72 also receives one or more coolant temperature signals T2 from the sensors 66 and / or 68; the ECU 72 can be programmed to responsive issue one or more command signals C3 to adjust the operation of the thermal subsystem of the fuel cell. Additional sensor signals S N can be received by the ECU 72, and additional control commands C N can be concomitantly issued from the ECU 72, for example to control any other subsystem or component shown and / or described herein. The ECU 72 can issue command signals to transfer the evolved hydrogen and liquid H 2 O from the cathode side 26 through the drain conduit 56 to the water separator 78 ( Figure 1 ), where the hydrogen and water from the cathode are combined with the depleted hydrogen discharged from the anode through the drain conduit / hose 50.

[0078] Continuing to refer to Figure 1 , the traction battery pack 82 contains an array of rechargeable lithium-based (secondary) battery pack modules 84. Aspects of the disclosed concepts can be similarly applied to other energy storage unit architectures, including those employing nickel-metal hydride (NiMH) battery packs, lead-acid battery packs, lithium-metal battery packs, or other suitable types of rechargeable electric vehicle battery packs (EVBs). Each battery pack module 84 can include a stack or cluster of electrochemical battery cells, such as pouch-type lithium-ion (Li-ion) or Li-ion polymer battery cells 86. A single battery pack module 84 can be represented, for example, by a set of 10 - 80 Li-ion battery cells, which are stacked in a side-by-side facing relationship with each other and connected in parallel or in series to store and supply electrical energy. Although described as a silicon-based, Li-ion "pouch cell" battery pack, the battery 86 can be applicable to other configurations, including cylindrical and prismatic configurations.

[0079] Figure 2Schematic top view of a part of the electrolysis system 100. In the illustrated example, the electrolysis system 100 includes an electrolyzer cell, such as a proton exchange membrane (PEM) electrolyzer cell. In one example, the PEM electrolyzer cell includes a cell stack formed by a plurality of stacked cells (e.g., in series), where each cell includes various components, including various membrane electrode assembly (MEA) components. The MEA component includes a solid polymer membrane (i.e., a proton exchange membrane or PEM) disposed between the anode and the cathode. The MEA component constituting the cathode includes a catalyst layer disposed adjacent to a gas diffusion layer (GDL). Similarly, the MEA component constituting the anode includes a catalyst layer disposed adjacent to a porous transport layer (PTL). As part of the electrolysis method, the PEM selectively allows positively charged hydrogen ions to pass through the membrane between the anode and the cathode in order to convert water into hydrogen and oxygen.

[0080] As Figure 2 shown in, the electrolysis system 100 includes a water source 102 that is in fluid communication with the electrolyzer stack 110 via a pipeline 104 to supply water feedstock to the electrolyzer stack 110. Any unused, remaining, and / or by-product water returns from the electrolyzer stack 110 to the water source 102 via a recycle stream pipeline 114. In addition, a power source 106 and power electronics 116 are in communication with the electrolyzer stack 110 via pipelines 108 and 114, respectively. In one or more embodiments of the present disclosure, a hydrogen storage device 118 is in fluid communication with the electrolyzer stack 110 via a pipeline 112 to receive the hydrogen product generated in the electrolysis method in the electrolyzer stack 110, as will be discussed in further detail below.

[0081] As shown, the electrolyzer stack 110 receives electricity (i.e., current) from the power source 106 via a pipeline 108 and water from the water source 102 via a pipeline 104. The electrolyzer stack 110 uses the electricity supplied by the power source 106 to convert water from the water source 102 into hydrogen and oxygen via electrolysis. Hydrogen gas is output from the electrolyzer stack 110 as a hydrogen product stream and enters the hydrogen storage device 118 via a pipeline 112.

[0082] During the operation of the electrolysis system 100, the power source 106 supplies direct current to the electrolyzer stack 110. Examples of power sources include, but are not limited to, battery packs, solar cells, DC generators, wind turbines, hydroelectric power plants, and / or similar devices.

[0083] The power electronics 116 is in communication with the electrolyzer stack 110 and is configured to control the operation of the electrolyzer stack 110. For example, the power electronics 116 can control the amount of voltage and current supplied from the power source 106 to the electrolyzer stack 110.

[0084] Figure 3 Shown along Figure 2Cross-sectional view of the electrolyzer stack 110 taken along line 3-3. In one or more embodiments of the present disclosure, the electrolyzer stack 110 includes a cell block 180 formed by a plurality of cells 182.

[0085] The plurality of cells 182 includes a plurality of seals 142 and a plurality of separators 140. The cells among the plurality of cells 182 are stacked in the cell block 180 and electrically connected in series. Each cell among the plurality of cells 182 includes various components, including a membrane electrode assembly (MEA) 138, a pair of separators 140, and a pair of seals 142.

[0086] The pair of separators (from the plurality of separators 140) contains flow channels that engage with the MEA 138 and allow fluids (such as water, hydrogen, and oxygen) to flow into or out of the MEA 138. Each separator 140 is conductive and facilitates the transmission of electrons to help create the circuit of the electrolysis method.

[0087] As Figure 4 shown, the MEA 138 includes a solid polymer membrane (i.e., proton exchange membrane 28 or PEM), an anode 132 (i.e., anode catalyst layer), and a cathode 136 (i.e., cathode catalyst layer). The PEM 28 is disposed between the anode catalyst layer 132 and the cathode catalyst layer 136. The cathode catalyst layer 136 is disposed adjacent to a gas diffusion layer (GDL) 134. Similarly, the anode catalyst layer 132 is disposed adjacent to a porous transport layer (PTL) 130. In the case of a fuel cell, the GDL will be used instead of the PTL. The PEM 28 contains an active region where the electrochemical reaction of converting water to hydrogen via electrolysis occurs. As part of the electrolysis method, the PEM 28 selectively allows positively charged hydrogen ions to pass through the membrane between the anode 132 and the cathode 136 in order to convert water to hydrogen and oxygen.

[0088] Each cell 182 is constructed such that the MEA 138 is disposed between a pair of separators 140. The pair of seals (from the plurality of seals 142) prevents fluids (such as water, hydrogen, and oxygen) from leaking from the interface between the MEA 138 and the pair of separators 140. The pair of seals 142 defines the MEA perimeter. The MEA perimeter is the region where the fluid is restricted before leaving the MEA 138 via the pair of separators 140.

[0089] As Figure 5 shown, the membrane 28 includes a plurality of gas recombination layers 28-G and a plurality of reinforcement layers 28-R. In the illustrated example, adjacent reinforcement layers 28-R are separated from each other by at least one of the gas recombination layers 28-G. An ionomer layer 28-I is disposed adjacent to one of the plurality of reinforcement layers 28-R. One feature of the plurality of reinforcement layers 28-R is to reduce crack formation in the membrane 28.

[0090] At least one of the reinforcing layers 28-R separates the ionomer layer 28-I from the plurality of gas recombination layers 28-G. The reinforcing layer 28-R is composed of at least one of an ionomer-swollen woven matrix material or an ionomer-swollen non-woven matrix material. In the illustrated example, each of the plurality of reinforcing layers 28-R has the same thickness, and the matrix or composition between the layers is the same or different. At least one of the plurality of reinforcing layers may be composed of expanded polytetrafluoroethylene (ePTFE).

[0091] The gas recombination layer 28-G may include an ionomer having at least one gas recombination catalyst. The gas recombination catalyst may include at least one of platinum or palladium. The gas recombination catalyst is supported by a support structure including at least one of C, SiO 2 , TiO 2 , CeO 2 , Nb 2 O 5 or IrO x . The gas recombination catalyst may be distributed uniformly or non-uniformly in at least one gas recombination layer. In addition, the gas recombination catalyst may be distributed in the gas recombination layer 28-G as one of particles, fibers or flakes, and the gas recombination layer 28-G may have a gas recombination catalyst loading of about 0.1% to 99.9%. In another example, the gas recombination layer 28-G may have a gas recombination catalyst loading of about 0.1% to 50%.

[0092] The gas recombination layer 28-G may also overlap with the reinforcing layer to an extent of 0 to 100%. In the illustrated example, each gas recombination layer 28-G has the same thickness, and the uniformity or composition between the layers is the same or different. One characteristic of the gas recombination layer 28-G is that it reduces the permeation of hydrogen or oxygen through the membrane 28.

[0093] Except as shown in the figures or described below,[ Figure 6 Another exemplary membrane 228 similar to membrane 28 is shown. Elements that are similar or identical between membrane 228 and membrane 28 will include the same reference numerals, with a prefix "2" added in Figure 6 . As shown in Figure 6 , the gas recombination layer 228-G includes varying thicknesses, where the gas recombination layer 228-G between the reinforcing layers 228-R is thicker than the gas recombination layer 228-G adjacent to the periphery of the membrane 228.

[0094] Except as shown in the figures or described below,[ Figure 7 Another exemplary membrane 328 similar to membrane 28 is shown. Elements that are similar or identical between membrane 328 and membrane 28 will include the same reference numerals, with a prefix "3" added in Figure 7 . As shown in Figure 7As shown, the ionomer layer 328-I is located in the middle of the membrane 328. The first reinforcing layer 328-R separates the middle ionomer layer from another ionomer layer 328-I on the first side, and the second reinforcing layer 328-R separates the middle ionomer layer 328-I from the gas recombination layer 328-G on the second side.

[0095] Except as shown in the figures or described hereinafter, Figure 8 Another exemplary membrane 428 similar to membrane 28 is shown. Elements that are similar or identical between membrane 428 and membrane 28 will include the same reference numerals, with a prefix “4” added in Figure 8 this case. As Figure 8 shown, the gas recombination layer 428-G is located in the middle of the membrane 428 and is surrounded by the reinforcing layer 428-R. The ionomer layer 428-I is adjacent to each reinforcing layer 428-R, and the reinforcing layer 428-R is opposite to the gas recombination layer 428-G located between the reinforcing layers 428-R.

[0096] The terms “a” and “an” do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The term “or” means “and / or” unless the context clearly dictates otherwise. Throughout this specification, reference to “an aspect” means that a particular element (e.g., a feature, a structure, a step, or a property) described in connection with that aspect is included in at least one aspect described herein, and may or may not be present in other aspects. Additionally, it is to be understood that the elements may be combined in a suitable manner in the various aspects.

[0097] When an element such as a layer, a membrane, a region, or a substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, no intervening elements are present.

[0098] Unless otherwise specified herein, the test standards are the most recent standards in effect prior to the filing date of this application (or, if priority is claimed, the earliest priority application date on which the test standards appear).

[0099] Unless otherwise defined, the technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0100] Although the foregoing disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from the scope of the invention. Additionally, many modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from its scope. Accordingly, this disclosure is not intended to be limited to the particular embodiments disclosed, but will include embodiments falling within its scope.

Claims

1. A membrane electrode assembly, comprising: anode; a cathode adjacent to the cathode gas diffusion layer; and a proton exchange membrane (PEM) that separates the anode from the cathode; Wherein the PEM comprises: at least one gas recombination layer; at least one ionomer layer; and A plurality of reinforcement layers, each reinforcement layer having a pair of opposing surfaces, wherein one of the at least one gas recombination layer or the at least one ionomer layer is adjacent to each of the pair of opposing surfaces.

2. The assembly of claim 1 including an anode gas diffusion layer adjacent to the anode.

3. The assembly of claim 1 including a porous transport layer adjacent to the anode and on a side of the anode opposite the PEM.

4. The assembly of claim 1, wherein one of the plurality of reinforcement layers separates the at least one ionomer layer from the at least one gas recombination layer.

5. The assembly of claim 1, wherein the plurality of reinforcement layers are comprised of at least one of an ionomer swollen woven matrix material or an ionomer swollen nonwoven matrix material.

6. The assembly of claim 5, wherein each of the plurality of reinforcement layers differs in thickness, matrix, and material composition.

7. The assembly of claim 5, wherein each of the plurality of reinforcement layers is identical in thickness, matrix, and material composition.

8. The assembly of claim 5, wherein at least one of the plurality of reinforcement layers is comprised of expanded polytetrafluoroethylene (ePTFE).

9. The assembly of claim 1, wherein the at least one gas recombination layer comprises an ionomer having at least one gas recombination catalyst.

10. The assembly of claim 9, wherein the at least one gas recombination layer comprises a plurality of gas recombination layers, each of the plurality of gas recombination layers having a different thickness, uniformity, and composition.

Images