Alkaline membrane fuel cell assembly comprising a thin membrane and method of making same

A method of making an alkaline membrane fuel cell assembly is disclosed. The method may include: depositing a first catalyst layer on a first gas diffusion layer to form a first gas diffusion electrode; depositing a second catalyst layer one a second gas diffusion layer to form a second gas diffusion electrode; depositing a thin membrane on at least one of: the first catalyst layer and the second catalyst layer; joining together the first and second gas diffusion electrodes to form the alkaline fuel cell assembly such that the thin membrane is located between the first and second catalyst layers; and sealing the first and second gas diffusion layers, the first and second catalyst layers and the thin membrane from all sides.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Application of PCT International Application No. PCT/IL2019/050607, International Filing Date May 28, 2019, entitled: “ALKALINE MEMBRANE FUEL CELL ASSEMBLY COMPRISING A THIN MEMBRANE AND METHOD OF MAKING SAME”, published on Dec. 19, 2019, under PCT International Application Publication No. WO 2019/239399, which claims the priority of Israel Patent Application No. 259978, filed on Jun. 12, 2018, which is hereby incorporated by reference in entirety.

FIELD OF THE INVENTION

The present invention generally relates to alkaline membrane fuel cell assemblies and method of making such assemblies. More particularly, the present invention relates alkaline membrane fuel cell assemblies that includes a thin membrane and method of making such assemblies.

BACKGROUND OF THE INVENTION

Membrane-electrode assemblies (MEAs) are the core components of proton-exchange membrane fuel cells (PEMFCs) and anion-exchange membrane fuel cells (AEMFCs). Generally, the membranes are manufactured separately from the electrodes. The electrodes, anode and cathode, are deposited either on the membrane itself, a membrane known in the art as catalyst-coated membrane (CCM). Alternatively, the catalyst layers can be deposited on gas-diffusion layers (GDLs) known in the art as gas diffusion electrodes (GDEs) that are further pressed against the membrane.

Electrolyte membranes are usually freestanding sheets of a few tens of microns thick. They are generally made of ionomer and a supporting mesh, i.e. a microporous substrate, for improving their mechanical properties. Mesh reinforcement also limits the membrane swelling upon water uptake. Freestanding non-supported membranes have also been demonstrated, but they are mechanically weaker and therefore are usually thicker in order to have sufficient mechanical strength. Some membranes were prepared by a multi-layer deposition of a sequence of GDL, first catalyst layer, membrane, second catalyst layer followed by a deposition of another GDL.

The membrane plays multiple roles within the fuel cell. First, it provides a gas-tight separation between the two electrodes. It also conducts ions and transfer water between the two electrodes. In order to limit ohmic losses and fuel cell dry-out, it is essential to have membranes having high ionic conductivity, which in turn depends from the quality of the ionomer material. Another way is to decrease the membrane thickness. However, it becomes increasingly difficult to manufacture freestanding membranes with thicknesses in the range of a few tens of microns or below. Successful approaches to manufacturer ultra-thin freestanding membranes involved the use of the supporting mesh with relatively low porosity such that the ionomer fraction within the membrane is significantly reduced. This in turn compromises the benefit of reducing the thickness. At such low thicknesses, non-supported membranes do not exhibit sufficient mechanical strength to be form as freestanding membranes for use as fuel cell separator.

Therefore, there is a strong interest to make MEAs with very thin membranes while conserving a relatively high fraction of the ionomer. This would allow benefiting from the geometrical effect without compromise the intrinsic ionic conductivity of the membrane.

SUMMARY OF EMBODIMENTS OF THE INVENTION

Some aspects of the invention are related to a method of making an alkaline membrane fuel cell assembly. Embodiments of the method may include: depositing a first catalyst layer on a first gas diffusion layer to form a first gas diffusion electrode; depositing a second catalyst layer one a second gas diffusion layer to form a second gas diffusion electrode; depositing a thin membrane on at least one of: the first catalyst layer and the second catalyst layer; and joining together the first and second gas diffusion electrodes to form the alkaline fuel cell assembly such that the thin membrane is located between the first and second catalyst layers. In some embodiments, the total thickness of the thin membrane may be below 30 microns.

In some embodiments, joining together may include at least one of: mechanically pressing together the first and second gas diffusion electrodes and physico-chemical bonding that includes crosslinking the joined area. In some embodiments, at least one of the first gas diffusion layer and the second gas diffusion layer may include a microporous layer. In some embodiments, the method may further include: depositing a first portion of the thin membrane on the first catalyst layer; and depositing a second portion of the thin membrane on the second catalyst layer. In some embodiments, joining together the first and second gas diffusion electrodes comprises joining the first and second portions of the thin membrane. In some embodiments, the method may further include: crosslinking the thin membrane to at least one of the first catalyst layer and the second catalyst layer prior to joining.

In some embodiments, the method may further include functionalizing the thin membrane prior to joining. In some embodiments, depositing the thin membrane may include depositing a dispersion comprising monomers or functionalized monomers and the method may further include: polymerizing the monomers or polymerizing the functionalized monomers. In some embodiments, depositing the thin membrane may include depositing a dispersion comprising polymerized polymer chains. In some embodiments, the dispersion further may include reinforcing nanoparticles. In some embodiments, the method may further include wetting the thin membrane by a base followed by dionized water, to cause ion-exchanging of anions in the membrane into anions, prior to the joining.

In some embodiments, the method may include sealing the alkaline fuel cell assembly. In some embodiments, the method may include sealing the alkaline membrane fuel cell assembly from all sides substantially perpendicular to surfaces of the first and the second gas diffusion electrodes. In some embodiments, the sealing may include adding gaskets to the sides substantially perpendicular to surfaces of the first and the second gas diffusion electrodes. In some embodiments, the sealing may include infusing a sealing material from all the sides substantially perpendicular to of the first and the second gas diffusion electrodes.

In some embodiments, depositing the thin membrane may include depositing two or more layers each comprising a different ionomer. In some embodiments, the ionomers are different by at least one of: the chemical composition and/or the ion-exchange capacity (IEC).

Some additional aspects of the invention may be related to an alkaline fuel cell assembly. Embodiments of the alkaline fuel cell assembly may include: a first gas diffusion layer coated with a first catalyst layer to form a first gas diffusion electrode; a second gas diffusion layer coated with a second catalyst layer to form a second gas diffusion electrode; and a thin membrane coated on at least one of: the first catalyst layer and the second catalyst layer, alkaline fuel cell assembly the first and second gas diffusion electrodes may be joined together to form the alkaline fuel cell assembly such that the thin membrane is located between the first and second catalyst layers. In some embodiments, the total thickness of the thin membrane may be at most 30 microns.

In some embodiments, the joined area may include at least one of: mechanically pressed area and crosslinking chemical bonds. In some embodiments, at least one of the first gas diffusion layer and the second gas diffusion layer may include a microporous layer. In some embodiments, a first portion of the membrane may coated the first catalyst layer and a second portion of the membrane may coat the second catalyst layer.

In some embodiments, the joined area may join the first and second portions of the membrane. In some embodiments, the alkaline fuel cell assembly may further include a seal for sealing the alkaline membrane fuel cell assembly. In some embodiments, the alkaline fuel cell assembly may further include a seal for sealing the alkaline membrane fuel cell assembly from all sides substantially perpendicular to surfaces of the first and the second gas diffusion electrodes. In some embodiments, the seal may include gaskets attached to the sides substantially perpendicular to surfaces of the first and the second gas diffusion electrodes. In some embodiments, the seal may include a sealing material infused on the sides substantially perpendicular to surfaces of the first and the second gas diffusion electrodes.

In some embodiments, the thin membrane may include ionomer and reinforcing nanoparticles.

Some other aspects of the invention may be related to a kit for forming alkaline fuel cell assembly. Embodiments of the kit may include: a first gas diffusion electrode coated with a first catalyst layer; a second gas diffusion electrode coated with a second catalyst layer; and a thin membrane coating at least one of: the first catalyst layer and the second catalyst layer. In some embodiments, the first and second gas diffusion electrodes may be configured to be joined together to form the alkaline fuel cell assembly such that the thin membrane is located between the first and second catalyst layers. In some embodiments, the total thickness of the thin membrane may be at most 30 microns.

Some other aspects of the invention may be related to a method of making an alkaline membrane fuel cell assembly. Embodiments of the method may include providing a first gas diffusion electrode comprising a first catalyst layer deposited on a first gas diffusion layer; providing a second gas diffusion electrode comprising a second catalyst layer deposited on a first gas diffusion layer; depositing a thin membrane on at least one of: the first catalyst layer and the second catalyst layer; and joining together the first and second gas diffusion electrodes to form the alkaline fuel cell assembly such that the thin membrane is located between the first and second catalyst layers. In some embodiments, the total thickness of the thin membrane is below 30 microns.

In some embodiments, joining together may include at least one of: mechanically pressing together the first and second gas diffusion electrodes and physico-chemical bonding that includes crosslinking the joined area. In some embodiments, at least one of the first gas diffusion layer and the second gas diffusion layer may include a microporous layer.

In some embodiments, the method may further include depositing a first portion of the thin membrane of the first catalyst layer; and depositing a second portion of the thin membrane of the second catalyst layer. In some embodiments, joining together the first and second gas diffusion electrodes may include joining the first and second portions of the thin membrane. In some embodiments, the method may further include crosslinking the thin membrane to at least one of the first catalyst layer and the second catalyst layer prior to joining. In some embodiments, the method may further include functionalizing the thin membrane prior to joining.

In some embodiments, depositing the thin membrane may include depositing a dispersion comprising monomers or functionalized monomers and the method further include polymerizing the monomers or polymerizing the functionalized monomers. In some embodiments, depositing the thin membrane comprises depositing a dispersion may include polymerized polymer chains. In some embodiments, the dispersion further comprises reinforcing nanoparticles. In some embodiments, the method may further include: wetting the thin membrane by a base followed by dionized water, to cause ion-exchanging of anions in the membrane into anions, prior to the joining. In some embodiments, the method may further include sealing the alkaline fuel cell assembly.

In some embodiments, the method may further include: sealing the alkaline membrane fuel cell assembly from all sides perpendicular to surfaces of the first and the second gas diffusion electrodes. In some embodiments, the sealing may include adding gaskets to the sides perpendicular to the non-deposited surfaces. In some embodiments, the sealing may include infusing a sealing material from all the sides perpendicular to the non-deposited surfaces. In some embodiments, depositing the thin membrane may include depositing two or more layers each comprising a different ionomer. In some embodiments, the ionomers are different by at least one of: the chemical composition and/or the ion-exchange capacity (IEC).

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Some aspects of the present invention may be related to methods of making an alkaline membrane fuel cell assembly that include a thin membrane (e.g., having a thickness of less than 30 microns). In such fuel assembly the thin membrane may be deposited directly on at least one catalyst layer as oppose to the standard methods wherein the catalyst layers are deposited on both sides of the membrane to form a CCM. Such a method may allow to reduce the thickness of the membrane to well below 30 microns, for example, below 20 micron, 10 microns and 5 microns. Such a thin membrane may have several advantages, for example, dramatic reduction of the swelling phenomenon and the redundancy of the use of mesh as a support, as well as high conductance of the membrane (conductance is conductivity divided by thickness) and higher water permeation.

Furthermore, a method of making such an alkaline membrane fuel cell assembly according to some embodiments of the invention may allow better, simpler and cheaper production of AEMFC assemblies. The method may include preparing or providing an anode gas diffusion electrode (GDE which is an anode catalyst layer deposited on a GDL) and a cathode GDE (cathode catalyst layer deposited on a GDL) following by depositing the thin membrane on one or both catalyst layers of the GDEs and then joining the two GDEs together. GDEs are cheaper than the more expensive CCM. Embodiments of such method may allow wetting the thin membrane by a base followed by deionized water, to cause ion-exchanging of anions in the membrane, before the joining. This may allow simpler, quicker and more uniform ion-exchanging process in the membrane. In some embodiments, the two GDEs in which at least one is deposited with the thin membrane may be stored as a kit to be joined and optionally ion-exchanged when needed.

Reference is now made toFIGS.1A and1Bwhich are illustrations of a kit for forming alkaline fuel cell assembly and a fuel cell assembly according to some embodiments of the invention. In some embodiments, a kit105for alkaline fuel cell assembly and a fuel cell assembly100may include a first gas diffusion electrode110and a second gas diffusion electrode120. First gas diffusion electrode110may include a first gas diffusion layer12coated with a first catalyst layer22and second gas diffusion electrode120may include a second gas diffusion layer14coated with a second catalyst layer24. In some embodiments, fuel cell assembly100and/or kit105may further include a thin membrane30coated on at least one of: a first catalyst layer22and a second catalyst layer24. For example, a first portion32of thin membrane30may be coated on first catalyst layer22and a second portion34of thin membrane30may be coated on second catalyst layer24.

Gas diffusion layers (GDL)s12and14may include any gas diffusion layers known in the art, for example, carbon paper, non-woven carbon felt, woven carbon cloth and the like. In some embodiments, GDLs12or14may include a microporous layer (MPL), that is made, for example, from sintered carbon/PTFE particles. In some embodiments, GDLs12and/or14may include the MPL is in order to provide a flat substrate to form a uniform deposition of the catalyst layer,

First catalyst layer22may be, for example, an anode catalyst layer that includes ionomer and anode catalyst particles, such as, nanoparticles of: Pt, Ir, Pd, Ru, Ni and the like and alloys of the like. Second catalyst layer24may be, for example, a cathode catalyst layers, that includes ionomer and cathode catalyst particles, for example, nanoparticles of: Ag, Ag alloyed with Pd, Cu, Zr and the like. The ionomer included in first catalyst layer22and second catalyst layer24may be ionomer configured to conduct anions. The ionomers of first catalyst layer22and second catalyst layer24may be different or may be the same. In some embodiments, ionomers of first catalyst layer22and second catalyst layer24may be the same as the ionomer of first portion32and second portion34of thin membrane30.

In some embodiments, first portion32and second portion34of thin membrane30may include any anion conducting ionomer known in the art, for example, copolymers of (Vinylbenzyl)trimethylammonium chloride, copolymers of diallyldimethylammonium chloride (DADMAC), styrene based polymer having quaternary ammonium anion conducting group, Bi-Phenyl backboned with two functional groups: an alkene tether group and alkyl halide group, and the like. In some embodiments, the total thickness of thin membrane30may be at most 30 microns, for example, at most 20 microns, at most 10 microns and at most 5 microns. In some embodiments, first portion32and second portion34may further include reinforcing nanoparticles, for increasing the strength of thin membrane30. For example, the ionomer of thin membrane30may be reinforced with, for example, anionic clays, cationic clays, graphene oxide, reduced graphene oxide, zirconium oxide, titanium oxide, polytetrafluoroethylene nanoparticles, boron nitride and the like.

In some embodiments, first gas diffusion electrode110and second gas diffusion electrode120may be joined together to form alkaline fuel cell assembly100such that thin membrane30may be located between the first and second catalyst layers22and24. In some embodiments, alkaline fuel cell assembly100may include a joined area40, joining together first gas diffusion electrode110and second gas diffusion electrode120. In some embodiments, joined area40may include at least one of: mechanically pressed area and crosslinking chemical bonds.

Reference is now made toFIGS.2A and2Bwhich are illustrations of a kit for forming alkaline fuel cell assembly and a fuel cell assembly according to some embodiments of the invention. In some embodiments, a kit205of an alkaline fuel cell assembly and a fuel cell assembly200may include a first gas diffusion electrode210and a second gas diffusion electrode220. First gas diffusion electrode110may include a first gas diffusion layer12coated with a first catalyst layer22and second gas diffusion electrode120may include a second gas diffusion layer14coated with a second catalyst layer24. In some embodiments, fuel cell assembly200may further include a thin membrane30coated on a second catalyst layer24.

First gas diffusion electrode210and second gas diffusion electrode220may be substantially the same and may include the same layers as first gas diffusion electrode110and second gas diffusion electrode120of assembly100ofFIGS.1A and1B.

In some embodiments, thin membrane30may include any anion conducting ionomer known in the art, for example, copolymers of (Vinylbenzyl)trimethylammonium chloride, copolymers of diallyldimethylammonium chloride (DADMAC)), styrene based polymer having quaternary ammonium anion conducting group, Bi-Phenyl backboned with two functional groups: an alkene tether group and alkyl halide group, and the like. In some embodiments, the total thickness of thin membrane30may be at most 30 microns, for example, at most 20 microns, at most 10 microns and at most 5 microns. In some embodiments, thin membrane30may further include reinforcing nanoparticles, for increasing the strength of thin membrane30. For example, the ionomer of thin membrane30may be reinforced with, for example, anionic clays, cationic clays, graphene oxide, reduced graphene oxide, zirconium oxide, titanium oxide, polytetrafluoroethylene nanoparticles, boron nitride and the like.

In some embodiments, first gas diffusion electrode210and second gas diffusion electrode220may be joined together to form alkaline fuel cell assembly200such that thin membrane30may be located between the first and second catalyst layers22and24. In some embodiments, alkaline fuel cell assembly200may include a joined area40, joining together first gas diffusion electrode210and second gas diffusion electrode220. In some embodiments, joined area40may include at least one of: mechanically pressed area and crosslinking chemical bonds.

Reference are now made toFIGS.3A-3Cwhich are illustrations of sealed fuel cell assemblies according to some embodiments of the invention. In some embodiments, fuel cell assemblies100or200may further include a seal50,52,58for sealing the electro-chemically active areas of alkaline membrane fuel cell assembly. As used herein the electro-chemically active areas are areas at which electro-chemical reactions and ion conduction is taking place. In some embodiments, the electro-chemically active areas may include the GDLs, the catalyst layers and the membrane. In some embodiments, the seal may be configured to seal fuel cell assemblies100or200from all sides310substantially perpendicular to surfaces320and330of first and the second gas diffusion electrodes110and120. In some embodiments, the seal may also be held between two flow fields5.

In some embodiments, the seal may include two or more gaskets50, as illustrated inFIG.3A. Gaskets50may include any flexible sealing material that may be configured to fit (optionally under pressure) and fill the entire space from all sides310substantially perpendicular to surfaces320and330of first and the second gas diffusion electrodes110and120(I don't see120inFIG.3). For example, gaskets50may include any type of elastomers either thermoset or thermoplastic, for example, SBS, SEBS, thermoplastic polyurethanes, fluoro-elastomers, SBR, NBR, EDPM, BR, epichlorohydrin, silicone rubbers, fluorinated thermoset rubbers, thermoset polyurethanes and the like. In some embodiments, at least one of the two or more gaskets50may include a ridged material, for example, Kapton (polyimide), PTFE and the like.

In some embodiments, additional sub gaskets52may be added to further seal the chemically active areas, as illustrated inFIG.3B. Sub-gaskets may further seal the active area. For example, sub-gaskets52may include any type of sealing material either elastic or rigid. In some embodiments, the sub-gaskets may be made from the same material as gaskets50. In some sub-gaskets52may be made from a rigid material, for example, Kapton (polyimide), PTFE and the like.

In some embodiments, a sealing material58may be infused to seal fuel cell assemblies100or200from all sides310substantially perpendicular to surfaces320and330of first and the second gas diffusion electrodes110and120. Sealing material58, may be any flowable material that can be infused to completely fill the entire space from all sides310. Sealing material58may include a silicone-based polymer, for example, a thermoset silicone rubber, a thermoplastic such as polyurethane and the like.

Reference is now made toFIG.4which is a flowchart of a method of making an alkaline membrane fuel cell assembly. In some embodiments, in box410, a first catalyst layer (e.g., an anode catalyst layer) may be deposited on a first gas diffusion layer to form a first gas diffusion electrode (GDE). In some embodiments, a first GDE110may already be provided with first catalyst layer22deposited on GDL12. In some embodiments, GDL12may be provided and catalyst layer22may be deposited on one surface of GDL12, using any known method, for example, spraying, electrospray coating, slot die casting, printing and the like.

In some embodiments, in box420, a second catalyst layer (e.g., a cathode catalyst layer) may be deposited on a second gas diffusion layer to form a second gas diffusion electrode (GDE). In some embodiments, a second GDE120may already be provided with second catalyst layer24deposited on second GDL14. In some embodiments, GDL14may be provided and catalyst layer24may be deposited on one surface of GDL14, using any known method, for example, spraying, electrospray coating, slot die casting, printing and the like.

In some embodiments, in box430, a thin membrane may be deposited on at least one of: the first catalyst layer and the second catalyst layer. For example, thin membrane30may be deposited on at least one of first catalyst layer12of GDE210or second catalyst layer14of GDE220(as illustrated inFIG.2A). Alternatively, first portion32of thin membrane30may be deposited on the first catalyst layer and second portion34of thin membrane30may be deposited on second catalyst layer14(as illustrated inFIG.1A). In some embodiments, a dispersion for forming the thin membrane may be deposited using any known method, for example, spraying, electrospray coating, slot die casting, printing and the like. The dispersion may include monomers that may or may not include functional groups for forming the ionomer (functionalized monomers). Some examples of functional monomers may include, Vinylbenzyl)trimethylammonium chloride, dimethylammonium chloride (DADMAC) and the like. Some examples of functional or non-functional co-monomers may include, styrene, divinyl benzene, isoprene, butadiene, acrylamide and the like. The monomers may then be polymerized following the deposition. Alternatively, the dispersion may include already polymerized polymer chains either with or without functional groups, for example, Poly(vinyl benzene chloride) and its copolymers, poly(vinylbenzyl)trimethylammonium chloride) and its copolymers, poly(diallyldimethyl ammonium chloride) and the like. In some embodiments, if the monomers or polymers in the dispersion are not functionalized, embodiments may include functionalizing the deposited membrane. For example, transforming a chloromethylated group (non-functional) to a trimethylammonium group (functional), following by adding trimethylamine (TMA) to cause a chemical reaction is known in the art as “quaternization”.

In some embodiments, depositing the thin membrane may include depositing two or more layers each comprising a different ionomer. In some embodiments, the ionomers may be different by at least one of: the chemical composition and/or the ion-exchange capacity (IEC). For example, two different types of ionomers may be deposited to form thin membrane30for example, using any two of the materials disclosed with respect to box430. Additionally or alternatively, the same ionomer may be deposited having different IEC (the concentration of functional groups in the polymer). For example, an ionomer having a lower IEC (e.g., 0.2-6 mmol/gr) may be deposited at the anode side, for example, at first portion32of thin membrane30and an ionomer having a higher IEC (e.g., 0.2-6 mmol/gr) may be deposited at the cathode side, for example, at second portion34of thin membrane34.

In some embodiments, the polymers in the thin membrane may further be crosslinked using any suitable crosslinking agent, for example, Divinylbenzene, N,N,N′,N′-Tetramethyl-1,6-hexanediamine (TMHDA), 1,4-diazabicyclo[2.2.2]octane (DABCO), glyoxal, glutaraldehyde, hydrocarbon chains, sulfur groups, siloxy groups, N-hydroxybenzotriazole groups, azide groups and the like. As should be understood by one skilled in the art the crosslinking agent may be selected according to the type of the ionomer to be crosslinked. Additionally or alternatively, thin membrane30may be crosslinked to at least one of first catalyst layer22and second catalyst layer24.

In some embodiments, in box440, the first and second gas diffusion electrodes may be joined together to form the alkaline fuel cell assembly such that the thin membrane is located between the first and second catalyst layers. For example, GDE210may be joined to GDE220having thin membrane30deposited thereon (as illustrated inFIGS.2A and2B). Alternatively, first portion32of thin membrane30and second portion34of thin membrane30may be joined together (as illustrated inFIGS.1A and1B), the two GDEs may be joined by at least one of: mechanically pressing together the first and second gas diffusion electrodes and physico-chemical bonding that includes crosslinking the joined area. The two GDEs may be pressed together either with or without an additional heat. Alternatively, the two GDEs may be attached to each other and then crosslinked by adding a crosslinking agent to the thin membrane dispersion. As should be understood by one skilled in the art, the two joining method disclosed are given as examples only and the invention as a whole is not limited to a specific from of joining.

In some embodiments, the method may further include wetting the thin membrane by a base followed by dionized water, to cause ion-exchanging of anions in the membrane into anions, prior to the joining. In some embodiments, the anions to be exchanged may include OH−, HCO3−, CO32−, and the like. Some examples for such bases may include sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), sodium bicarbonate (NaHCO3), potassium bicarbonate (KHCO3) and the like.

In some embodiments, the method may further include sealing the alkaline membrane fuel cell assembly from all sides substantially perpendicular to surfaces of the first and the second gas diffusion electrodes. In some embodiments, sealing may include adding gaskets to the sides perpendicular to surfaces320and330. In some embodiments, sealing may include infusing a sealing material from all the sides substantially perpendicular to of the first and the second gas diffusion electrodes

Unless explicitly stated, the method embodiments described herein are not constrained to a particular order in time or chronological sequence. Additionally, some of the described method elements may be skipped, or they may be repeated, during a sequence of operations of a method.