Hybrid electrocatalyst layer for membrane-based electrochemical devices and process for making same

Abstract

Hybrid electrocatalyst layers for electrochemical cells and processes for making the same are described. The hybrid electrocatalyst layer includes at least one ion conducting layer and at least one non-ion conducting catalyst layer. A process for making the hybrid electrocatalyst layer includes a sintering step that provides greater durability of the hybrid electrocatalyst layer.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. application No. 18 / 778,577, filed on July 19, 2024, entitled “HYBRID ELECTROCATALYST LAYERS FORMEMBRANE-BASED ELECTROCHEMICAL DEVICES AND PROCESSES FOR MAKING THE SAME,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to hybrid electrocatalyst layers and processes for their fabrication for membrane-based electrochemical devices. Background Art

[0004] Electrochemical energy devices and reactors have traditionally used liquid electrolytes. In these devices and reactors, the goal for achieving good electrochemical activity is to maximize two-phase and three-phase contact, wherein the former relates to a device without gaseous reactants or products, and the latter is used for a device involving gaseous reactants and products. This can be achieved through micro- and macro-engineering of electrocatalysts, electrodes, and devices or reactors. The emergence of ion-conducting polymer membranes (e.g., polymers based on perfluorosulfonic acid (e.g., Nafion®)) has enabled new classes of electrochemical devices to be realized. However, the optimization of two-phase and three-phase now requires interaction with another dimension of solid-phase ion conductors.

[0005] What is needed is a membrane-based cell structure with an electrocatalyst layer that maximizes performance and durability. Summary of the Invention

[0006] Provided herein is a process for manufacturing an electrochemical cell. The process comprises: coating an ion-conducting slurry onto a transfer (decal) layer; drying the ion-conducting slurry to form an ion-conducting layer; transferring the ion-conducting layer from the transfer layer to an ion-conducting polymer membrane; coating a non-ion-conducting slurry onto a species diffusion / transport layer to form a coated species diffusion / transport layer; sintering the coated diffusion layer to form a non-ion-conducting catalyst layer on the species diffusion / transport layer; and hot pressing the non-ion-conducting catalyst layer onto the ion-conducting layer. In some embodiments, the sintering is performed at a temperature of about 300°C to about 400°C. In some embodiments, the ion-conducting slurry comprises a solvent, an ionomer (ion cross-linked polymer), and an electrocatalyst. In some embodiments, the non-ion-conducting slurry comprises a solvent, a non-ion-conducting binder, and an electrocatalyst. In some embodiments, the hot pressing is performed at a pressure of about 70 psi to about 150 psi and a temperature of about 80°C to about 140°C. In some embodiments, the transfer layer comprises a glass fiber layer coated with polytetrafluoroethylene. In some embodiments, the ion-conducting polymer membrane comprises a polymer based on perfluorosulfonic acid. In some embodiments, the ion-conducting slurry further comprises a pore former. In some aspects, the process further comprises removing the pore former from the ion-conducting layer before transferring the ion-conducting layer from the transfer layer to the ion-conducting polymer membrane. In some embodiments, the non-ion-conducting slurry further comprises a pore former. In some aspects, the process further comprises removing the pore former from the non-ion-conducting catalyst layer before hot pressing the non-ion-conducting catalyst layer onto the ion-conducting layer.

[0007] Further provided herein is a process for manufacturing an electrochemical cell, comprising: applying a non-ion-conducting slurry to a transfer layer; sintering the applied transfer layer to form a non-ion-conducting catalyst layer on the transfer layer; applying a sodium-type ion-conducting slurry comprising a sodium-type ionomer to the non-ion-conducting catalyst layer; drying the ion-conducting slurry to form a hybrid electrocatalyst layer comprising an ion-conducting layer and a non-ion-conducting catalyst layer; and hot pressing the hybrid electrocatalyst layer onto a sodium-type ion-conducting polymer membrane. In some embodiments, the sintering is performed at a temperature of about 300°C to about 400°C. In some embodiments, the ion-conducting slurry further comprises a solvent and an electrocatalyst. In some embodiments, the non-ion-conducting slurry comprises a solvent, a non-ion-conducting binder, and an electrocatalyst. In some embodiments, the hot pressing is performed at a pressure of about 70 psi to about 150 psi and a temperature of about 80°C to about 140°C. In some embodiments, the transfer layer comprises a glass fiber layer coated with polytetrafluoroethylene. In some embodiments, the sodium-form ion-conducting polymer membrane comprises a sodium-form perfluorosulfonic acid-based polymer. In some embodiments, the ion-conducting slurry further comprises a pore former. In some aspects, the process further comprises removing the pore former from the ion-conducting layer before transferring the ion-conducting layer from the transfer layer to the ion-conducting polymer membrane. In some embodiments, the non-ion-conducting slurry further comprises a pore former. In some aspects, the process further comprises removing the pore former from the non-ion-conducting catalyst layer before hot pressing the non-ion-conducting catalyst layer onto the ion-conducting layer.

[0008] Further provided herein is an electrochemical cell manufactured by the process described herein. The electrochemical cell comprises: an ion-conducting polymer membrane having a first surface and a second surface; a first hybrid electrocatalyst layer having a first surface and a second surface, the first surface of the first hybrid electrocatalyst layer being in contact with the first surface of the ion-conducting polymer membrane, the first hybrid electrocatalyst layer comprising: a first ion-conducting layer; and a first non-ion-conducting catalyst layer; a first mass diffusion / transport layer in contact with the second surface of the first hybrid electrocatalyst layer, wherein the first mass diffusion / transport layer is in contact with the first non-ion-conducting catalyst layer, and the ion-conducting polymer membrane is in contact with the first ion-conducting layer; a second hybrid electrocatalyst layer having a first surface and a second surface, the first surface of the second hybrid electrocatalyst layer being in contact with the second surface of the ion-conducting polymer membrane, the second hybrid electrocatalyst layer comprising: a second ion-conducting layer; and a second non-ion-conducting catalyst layer; and a second mass diffusion / transport layer in contact with the second surface of the second hybrid electrocatalyst layer, wherein the second mass diffusion / transport layer is in contact with the second non-ion-conducting catalyst layer, and the ion-conducting polymer membrane is in contact with the second ion-conducting layer.

[0009] In some embodiments, the electrochemical cell is suitable for use in an electrolyzer, a hydrogen pump, ammonia synthesis based on a gas / gas cell, or carbon dioxide electroreduction based on a gas / gas cell. In some embodiments, the first ion-conducting layer, the second ion-conducting layer, or both the first ion-conducting layer and the second ion-conducting layer comprise a plurality of ion-conducting layers. In some aspects, the plurality of ion-conducting layers define an ionomer concentration gradient along the thickness of the plurality of ion-conducting layers. In some aspects, the plurality of ion-conducting layers define a porosity gradient along the thickness of the plurality of ion-conducting layers. In some embodiments, the ion-conducting polymer membrane is a sodium-type ion-conducting polymer membrane. In some embodiments, the first ion-conducting layer and the second ion-conducting layer each comprise an ionomer. In some aspects, the ionomer is a sodium-type ionomer. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The present disclosure can be understood by reference to the following detailed description in conjunction with the accompanying drawings which are briefly described below. Note that for purposes of clarity of illustration, some elements in the drawings may not be drawn to scale.

[0011] Figure 1A A diagram showing an electrochemical cell of the present disclosure.

[0012] Figure 1B show Figure 1AAn enlarged view of the first hybrid electrocatalyst layer is shown in FIG.

[0013] Figure 1C A diagram showing an electrochemical cell of the present disclosure.

[0014] Figure 2A Shown is a process for making the hybrid electrocatalyst layers described herein.

[0015] Figure 2B Shown is a process for making the hybrid electrocatalyst layers described herein.

[0016] Figure 3A Shown is a process for making the hybrid electrocatalyst layers described herein.

[0017] Figure 3B Shown is a process for making the hybrid electrocatalyst layers described herein. DETAILED DESCRIPTION

[0018] The present disclosure relates to an electrochemical cell for use in a membrane electrode assembly including a hybrid electrocatalyst layer. As described in more detail below, the disclosed electrochemical cell includes an ion-conducting polymer membrane, a first hybrid electrocatalyst layer, a first mass diffusion / transport layer, a second hybrid electrocatalyst layer, and a second mass diffusion / transport layer. The disclosed electrochemical cell isolates the mass diffusion / transport layer from participating in the electrochemical reaction, thereby avoiding the production of peroxides and other undesirable compounds that can electrochemically damage the ion-conducting polymer membrane.

[0019] I. Electrochemical Cells

[0020] Figure 1A An electrochemical cell 100 of the present disclosure is shown. Membrane module 100 includes an ion-conducting polymer membrane 102, a first hybrid electrocatalyst layer 103 including a first ion-conducting catalyst layer 104 and a first non-ion-conducting catalyst layer 106, a second hybrid electrocatalyst layer 107 including a second ion-conducting catalyst layer 108 and a second non-ion-conducting catalyst layer 110, a first species diffusion / transport layer 112, and a second species diffusion / transport layer 114.

[0021] The ion-conducting polymer membrane 102 includes a first surface 130 and a second surface 131 opposite the first surface 130. The ion-conducting polymer membrane may include a proton exchange membrane (PEM), a cation exchange membrane (CEM), or an anion exchange membrane (AEM). The ion-conducting polymer membrane is formed of an ion-conducting polymer resin, such as a perfluorosulfonic acid-based polymer such as Nafion®, which has the formula A sulfonated tetrafluoroethylene-based fluoropolymer-copolymer wherein n is an integer from 3,000 to 10,000. Other ion-conducting polymer resins known in the art may also be used in the ion-conducting polymer membranes of the present disclosure, including sulfonated poly(etheretherketone) (SPEEK), sulfonated phenylated poly(phenylene) (SPPP), sulfonated poly(ethersulfone) (SPES), sulfonated poly(sulfone) (SPSU), sulfonated polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene (S-SEBS), a mixture of sulfonated poly(ethylene oxide) mixed with poly(vinyl alcohol), sulfonated polystyrene crosslinked with divinylbenzene, poly(benzimidazole) (PBI), poly(etherimide) (PEI), sulfonated poly(etherimide) (SPEI), and the like. Other ion-conducting polymer resins known for use in anion exchange membranes include perfluorinated polymer resins, poly(aryl ether sulfone) (PAES) and its derivatives, polyethylene (PE) and its derivatives, polyphenylene (PPN) and its derivatives, polystyrene (PS) and its derivatives, polyfluorene (PFN) and its derivatives, and the like.

[0022] In some embodiments, the ion-conducting polymer membrane 102 may be a sodium-type ion-conducting polymer membrane. The sodium-type ion-conducting polymer membrane is formed from an ion-conducting polymer membrane that has been boiled in a solution containing a low concentration (e.g., about 0.1 M) of sodium hydroxide (NaOH) for an extended period of time. This results in the resin being impregnated with sodium ions (Na + ). Compared with non-sodium-type ion-conducting polymer membranes, the obtained sodium-type ion-conducting polymer membrane has greater thermal stability.

[0023] Ion-conducting polymer membrane 102 may have a thickness of about 15 microns to about 125 microns. For example, ion-conducting polymer membrane 102 may have a thickness of about 15 microns to about 50 microns, about 50 microns to about 100 microns, or about 100 microns to about 125 microns. Those skilled in the art will recognize that thinner ion-conducting polymer membranes 102 may be used in fuel cells, while thicker ion-conducting polymer membranes may be used in electrolyzers.

[0024] The first hybrid electrocatalyst layer 103 includes a first ion-conducting catalyst layer 104 and a first non-ion-conducting catalyst layer 106. Figure 1AOnly a hybrid electrocatalyst layer containing two sublayers (one ion-conducting catalyst layer and one non-ion-conducting catalyst layer) is depicted, but one of ordinary skill in the art will understand that the hybrid electrocatalyst layer of the present disclosure may include more than two sublayers, such as one ion-conducting catalyst layer and two non-ion-conducting catalyst layers, two ion-conducting catalyst layers and one non-ion-conducting catalyst layer, two ion-conducting catalyst layers and two non-ion-conducting catalyst layers, and the like.

[0025] The first hybrid electrocatalyst layer 103 has a first surface 132 and a second surface 133 opposite to the first surface 132. The first surface 132 is in contact with the first material diffusion / transport layer 112, and the second surface 133 is in contact with the first surface 130 of the ion-conducting polymer membrane 102. Figure 1A As shown in FIG, first ion conducting layer catalyst 104 is in contact with ion conducting polymer membrane 102, and first non-ion conducting catalyst layer 106 is in contact with first species diffusion / transport layer 112.

[0026] The first hybrid electrocatalyst layer 103 includes an electrocatalyst. The electrocatalyst is present in both the first ion-conducting catalyst layer 104 and the first non-ion-conducting catalyst layer 106. The electrocatalyst particles closest to the ion-conducting polymer membrane 102 participate in the electrochemical reaction at the ion-conducting polymer membrane 102, while the electrocatalyst particles farthest from the ion-conducting polymer membrane 102 (i.e., the electrocatalyst particles closest to the first material diffusion / transport layer 112) do not participate in the electrochemical reaction and instead act only as an electron conductor / chemical catalyst. The electrocatalyst closer to the first material diffusion / transport layer 112 also catalyzes the conversion of undesirable chemicals into benign compounds. For example, the electrocatalyst closer to the first material diffusion / transport layer 112 can decompose peroxides in the non-ion-conducting catalyst layer into water and oxygen. In addition, the electrocatalyst can contribute to the downstream reaction of aldehydes, which are formed in the non-ion-conducting catalyst layer by the reduction reaction of carbon dioxide, carbon monoxide, and hydrogen in the ion-conducting layer.

[0027] The electrocatalyst may include platinum in the form of platinum black, alloyed transition metals, transition metals combined with a carbon source or a nitrogen source, or combinations thereof. For example, the catalyst may include platinum, rhodium, ruthenium, cobalt, titanium, vanadium, iron, nickel, copper, zinc, zirconium, silver, palladium, gold, other transition metals known in the art, oxides thereof, or alloys thereof. In some embodiments, the catalyst may include platinum, rhodium, ruthenium, cobalt, oxides thereof, or alloys thereof.

[0028] The electrocatalyst may be unsupported or supported on a conductive support. The conductive support may include a carbon support or a metal oxide support, such as antimony tin oxide, indium tin oxide, or substoichiometric titanium oxide.

[0029] The first ion-conducting catalyst layer 104 includes an ionomer and the electrocatalyst described above. The ionomer particles are dispersed throughout the electrocatalyst particles (e.g., Figure 1B ) and acts as a binder. The ionomer comprises the same material as the ion-conducting polymer membrane 102 discussed above. Therefore, the presence of the ionomer expands the reaction zone of the ion-conducting polymer membrane 102 from a two-dimensional surface to three dimensions. In some embodiments, the ionomer may be a sodium-type ionomer. The sodium-type ionomer comprises the same material as the sodium-type ion-conducting polymer membrane described above. The electrocatalyst in the first ion-conducting catalyst layer 104 may be unsupported or may be supported on a conductive support. The conductive support may include a carbon support.

[0030] The ionomer can be present in first ion conducting catalyst layer 104 in an amount of about 1% to about 20% by weight of first ion conducting catalyst layer 104. For example, the ionomer can be present in the first ion conducting catalyst layer in an amount of about 1% to about 5%, about 1% to about 10%, about 1% to about 15%, about 1% to about 20%, about 5% to about 10%, about 5% to about 15%, about 5% to about 20%, about 10% to about 20%, or about 10% to about 15%, based on the weight of the first ion conducting catalyst layer. As another example, the ionomer can be present in the first ion conducting catalyst layer in an amount of about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, or about 20%, based on the weight of the first ion conducting catalyst layer.

[0031] The ionomer may be present in first ion-conducting catalyst layer 104 in an amount of about 30 vol % to about 40 vol %, for example, about 30 vol %, about 35 vol %, or about 40 vol %.

[0032] The electrocatalyst can be present in first ion conducting catalyst layer 104 in an amount of about 80% to about 99% by weight of first ion conducting catalyst layer 104. For example, the electrocatalyst can be present in the first ion conducting catalyst layer in an amount of about 80% to about 85%, about 80% to about 90%, about 80% to about 95%, about 85% to about 90%, about 85% to about 95%, about 85% to about 99%, about 90% to about 95%, about 90% to about 99%, or about 95% to about 99% by weight of the first ion conducting catalyst layer. As another example, the electrocatalyst can be present in the first ion conducting catalyst layer in an amount of about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% by weight of the first ion conducting catalyst layer.

[0033] In an alternative embodiment, first ion-conducting catalyst layer 104 may include a support for an electrocatalyst as described above, but it does not include an electrocatalyst. This facilitates the formation of a three-dimensional network of ionomer, conductive support, and catalyst through the ion-conducting catalyst layer.

[0034] First ion conducting catalyst layer 104 may have a porosity of about 10% to about 30%. For example, first ion conducting catalyst layer 104 may have a porosity of about 10% to about 15%, about 10% to about 20%, about 10% to about 25%, about 10% to about 30%, about 15% to about 20%, about 15% to about 25%, about 15% to about 30%, about 20% to about 25%, about 20% to about 30%, or about 25% to about 30%. The porosity of first ion conducting catalyst layer 104 can be measured by means known to those skilled in the art.

[0035] The first non-ion-conducting catalyst layer 106 includes the above-mentioned electrocatalyst and a non-conductive binder. The non-conductive binder may include a polymer such as polytetrafluoroethylene (PTFE, also known as Teflon®), poly(etheretherketone) (PEEK), poly(benzimidazole) (PBI), poly(vinylidene fluoride) (PVDF), phenylated poly(phenylene) (PPP), poly(ethersulfone) (PES), polystyrene-block-poly(ethylene-random-butylene)-block-polystyrene (SEBS), a mixture of poly(ethylene oxide) mixed with poly(vinyl alcohol), polystyrene cross-linked with divinylbenzene, poly(etherimide) (PEI), or other non-conductive binders known in the art. The electrocatalyst in the first non-ion-conducting catalyst layer 106 may be unsupported or supported on a conductive support. The conductive support may include a carbon support.

[0036] The binder can be present in the first non-ion-conducting catalyst layer 106 in an amount of about 1% to about 20% by weight of the first non-ion-conducting catalyst layer 106. For example, the binder can be present in the first non-ion-conducting catalyst layer in an amount of about 1% to about 5%, about 1% to about 10%, about 1% to about 15%, about 1% to about 20%, about 5% to about 10%, about 5% to about 15%, about 5% to about 20%, about 10% to about 20%, or about 10% to about 15%, based on the weight of the first non-ion-conducting catalyst layer. As another example, the binder can be present in the first non-ion-conducting catalyst layer in an amount of about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, or about 20%, based on the weight of the first non-ion-conducting catalyst layer.

[0037] The non-conductive binder may be present in the first non-ion-conducting catalyst layer 106 in an amount of about 30 volume % to about 40 volume %, for example, about 30 volume %, about 35 volume %, or about 40 volume %.

[0038] The electrocatalyst may be present in the first non-ion conducting catalyst layer 106 in an amount from about 80% to about 99% by weight of the first non-ion conducting catalyst layer 106. For example, the electrocatalyst may be present in the first non-ion conducting catalyst layer in an amount from about 80% to about 85%, from about 80% to about 90%, from about 80% to about 95%, from about 85% to about 90%, from about 85% to about 95%, from about 85% to about 99%, from about 90% to about 95%, from about 90% to about 99%, or from about 95% to about 99% by weight of the first non-ion conducting catalyst layer. As another example, the electrocatalyst may be present in the first non ion conducting catalyst layer in an amount of about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% by weight of the first non ion conducting catalyst layer.

[0039] The first non-ion-conducting catalyst layer 106 may have a porosity of about 10% to about 30%. For example, the first non-ion-conducting catalyst layer 106 may have a porosity of about 10% to about 15%, about 10% to about 20%, about 10% to about 25%, about 10% to about 30%, about 15% to about 20%, about 15% to about 25%, about 15% to about 30%, about 20% to about 25%, about 20% to about 30%, or about 25% to about 30%. The porosity of the first non-ion-conducting catalyst layer 106 can be measured by means known to those skilled in the art.

[0040] In an alternative embodiment, the first non-ion-conducting catalyst layer 106 may include a support for an electrocatalyst as described above, but it does not include an electrocatalyst. This helps form a three-dimensional network of binder, conductive support, and catalyst through the non-ion-conducting catalyst layer.

[0041] In some embodiments, the ion-conducting catalyst layer may include a non-ion-conducting binder, and the non-ion-conducting catalyst layer may include an ionomer.

[0042] The first mass diffusion / transport layer 112 is made of an electrically conductive material that is both gas-permeable and liquid-permeable. Methods for manufacturing and obtaining mass diffusion / transport layers are generally known to those skilled in the art.

[0043] Figure 1B An enlarged view of the first hybrid electrocatalyst layer 103 is shown. Figure 1BAs can be seen in FIG, electrocatalyst particles 118 are present throughout the thickness of first hybrid electrocatalyst layer 103. First ion-conducting catalyst layer 104 includes ionomer particles 120 that extend throughout the thickness of first ion-conducting catalyst layer 104. First non-ion-conducting catalyst layer 106 includes non-conductive binder particles 122 that extend throughout the thickness of first non-ion-conducting catalyst layer 106.

[0044] Back to Figure 1A The second hybrid electrocatalyst layer 107 has a first surface 134 and a second surface 135 opposite to the first surface 134. The first surface 134 contacts the second surface 131 of the ion-conducting polymer membrane 102, and the second surface 135 contacts the second material diffusion / transport layer 114. Figure 1A As shown in FIG, second ion conducting layer 108 is in contact with ion conducting polymer membrane 102 , and second non-ion conducting catalyst layer 110 is in contact with second species diffusion / transport layer 114 .

[0045] The second hybrid electrocatalyst layer 107 includes an electrocatalyst. The electrocatalyst is present in both the second ion-conducting catalyst layer 108 and the second non-ion-conducting catalyst layer 110. The electrocatalyst particles closest to the ion-conducting polymer membrane 102 participate in the electrochemical reaction at the ion-conducting polymer membrane 102, while the electrocatalyst particles farthest from the ion-conducting polymer membrane 102 (i.e., the electrocatalyst particles closest to the second material diffusion / transport layer 114) do not participate in the electrochemical reaction, but instead act only as an electron conductor / chemical catalyst. This portion of the electrocatalyst layer also catalyzes the conversion of undesirable chemicals into benign compounds. For example, the electrocatalyst can decompose peroxides that can be formed in the non-ion-conducting catalyst layer into water and oxygen. In addition, the electrocatalyst can help form aldehydes, which are formed at the non-ion-conducting catalyst layer by the reduction reaction of carbon dioxide, carbon monoxide, and hydrogen in the ion-conducting layer.

[0046] The electrocatalyst may comprise platinum in the form of platinum black, an alloyed transition metal, a transition metal in combination with a carbon source or a nitrogen source, or a combination thereof. The alloyed transition metal may comprise titanium, vanadium, iron, cobalt, nickel, copper, zinc, zirconium, ruthenium, rhodium, silver, palladium, gold, or other transition metals known in the art.

[0047] The electrocatalyst in the second hybrid electrocatalyst layer 107 may be unsupported or supported on a conductive support, which may include a carbon support or a metal oxide support, such as antimony tin oxide, indium tin oxide, or substoichiometric titanium oxide.

[0048] The second ion-conducting catalyst layer 108 includes the above-mentioned electrocatalyst and ionomer. The ionomer particles are dispersed throughout the electrocatalyst particles (e.g., Figure 1B The ionomer comprises the same material as that discussed above for ion-conducting polymer membrane 102. Thus, the presence of the ionomer expands the reaction zone of ion-conducting polymer membrane 102 from a two-dimensional surface to three dimensions. The electrocatalyst in second ion-conducting catalyst layer 108 may be unsupported or supported on a conductive support. The conductive support may comprise a carbon support or a metal oxide support, such as antimony tin oxide, indium tin oxide, or substoichiometric titanium oxide.

[0049] The ionomer may be present in second ion conducting catalyst layer 108 in an amount of about 1% to about 20% by weight of second ion conducting catalyst layer 108. For example, the ionomer may be present in the second ion conducting catalyst layer in an amount of about 5% to about 10%, about 5% to about 15%, about 5% to about 20%, about 10% to about 20%, or about 10% to about 15% by weight of the second ion conducting catalyst layer. As another example, the ionomer may be present in the second ion conducting catalyst layer in an amount of about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, or about 20% by weight of the second ion conducting catalyst layer.

[0050] The ionomer may be present in second ion-conducting catalyst layer 108 in an amount of about 30 vol % to about 40 vol %, for example, about 30 vol %, about 35 vol %, or about 40 vol %.

[0051] The electrocatalyst can be present in second ion conducting catalyst layer 108 in an amount from about 80% to about 99% by weight of second ion conducting catalyst layer 108. For example, the electrocatalyst can be present in the second ion conducting catalyst layer in an amount from about 80% to about 85%, from about 80% to about 90%, from about 80% to about 95%, from about 85% to about 90%, from about 85% to about 95%, from about 85% to about 99%, from about 90% to about 95%, from about 90% to about 99%, or from about 95% to about 99% by weight of the second ion conducting catalyst layer. As another example, the electrocatalyst can be present in the second ion conducting catalyst layer in an amount from about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% by weight of the second ion conducting catalyst layer.

[0052] Second ion conducting catalyst layer 108 may have a porosity of about 10% to 30%. For example, first ion conducting catalyst layer 108 may have a porosity of about 10% to about 15%, about 10% to about 20%, about 10% to about 25%, about 10% to about 30%, about 15% to about 20%, about 15% to about 25%, about 15% to about 30%, about 20% to about 25%, about 20% to about 30%, or about 25% to about 30%. The porosity of second ion conducting catalyst layer 108 can be measured by means known to those skilled in the art.

[0053] In an alternative embodiment, second ion-conducting catalyst layer 108 may include a support for an electrocatalyst as described above, but it does not include an electrocatalyst. This helps form a three-dimensional network of binder, conductive support, and catalyst through the ion-conducting catalyst layer.

[0054] The second non-ion-conducting catalyst layer 110 includes the above-mentioned electrocatalyst and a non-conductive binder. The non-conductive binder may include a polymer such as polytetrafluoroethylene (PTFE, also known as Teflon®), poly(etheretherketone) (PEEK), poly(benzimidazole) (PBI), poly(vinylidene fluoride) (PVDF), phenylated poly(phenylene) (PPP), poly(ethersulfone) (PES), polystyrene-block-poly(ethylene-random-butylene)-block-polystyrene (SEBS), a mixture of poly(ethylene oxide) mixed with poly(vinyl alcohol), polystyrene cross-linked with divinylbenzene, poly(etherimide) (PEI), or other non-conductive binders known in the art. The electrocatalyst in the second non-ion-conducting catalyst layer 110 may be unsupported or supported on a conductive support. The conductive support may include a carbon support or a metal oxide support, such as antimony tin oxide, indium tin oxide, or substoichiometric titanium oxide.

[0055] The binder may be present in the second non-ion-conducting catalyst layer 110 in an amount of about 1% to about 20% by weight of the second non-ion-conducting catalyst layer 110. For example, the binder may be present in the second non-ion-conducting catalyst layer in an amount of about 1% to about 5%, about 1% to about 10%, about 1% to about 15%, about 1% to about 20%, about 5% to about 10%, about 5% to about 15%, about 5% to about 20%, about 10% to about 20%, or about 10% to about 15%, based on the weight of the second non-ion-conducting catalyst layer. As another example, the binder may be present in the second non-ion-conducting catalyst layer in an amount of about 1%, about 2%, about 3%, about 4%, about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, or about 20%, based on the weight of the second non-ion-conducting catalyst layer.

[0056] The non-conductive binder may be present in the second non-ion-conductive catalyst layer 110 in an amount of about 30 volume % to about 40 volume %, for example, about 30 volume %, about 35 volume %, or about 40 volume %.

[0057] The electrocatalyst may be present in the second non-ion conducting catalyst layer 110 in an amount from about 80% to about 99% by weight of the second non-ion conducting catalyst layer 110. For example, the electrocatalyst may be present in the second non-ion conducting catalyst layer in an amount from about 80% to about 85%, from about 80% to about 90%, from about 80% to about 95%, from about 85% to about 90%, from about 85% to about 95%, from about 85% to about 99%, from about 90% to about 95%, from about 90% to about 99%, or from about 95% to about 99% by weight of the second non-ion conducting catalyst layer. As another example, the electrocatalyst may be present in the second non ion conducting catalyst layer in an amount of about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, or about 99% by weight of the second non ion conducting catalyst layer.

[0058] Second non-ion-conducting catalyst layer 110 may have a porosity of about 10% to about 30%. For example, second non-ion-conducting catalyst layer 110 may have a porosity of about 10% to about 15%, about 10% to about 20%, about 10% to about 25%, about 10% to about 30%, about 15% to about 20%, about 15% to about 25%, about 15% to about 30%, about 20% to about 25%, about 20% to about 30%, or about 25% to about 30%. The porosity of second non-ion-conducting catalyst layer 110 can be measured by means known to those skilled in the art.

[0059] In an alternative embodiment, the second non-ion-conducting catalyst layer 110 may include a support for the electrocatalyst as described above, but does not include the electrocatalyst. This helps form a three-dimensional network of binder, conductive support, and catalyst through the non-ion-conducting catalyst layer.

[0060] The second mass diffusion / transport layer 114 is made of an electrically conductive material that is both gas-permeable and liquid-permeable. Methods for manufacturing and obtaining mass diffusion / transport layers are generally known to those skilled in the art.

[0061] Figure 1C Another embodiment of the electrochemical cell 100 of the present disclosure is shown, in which the first hybrid electrocatalyst layer 103 and the second hybrid electrocatalyst layer 107 each include multiple ion-conducting catalyst layers and multiple non-ion-conducting catalyst layers. Thus, the hybrid electrocatalyst layer of the present disclosure may include more than 2 ion-conducting catalyst layers, more than 5 ion-conducting catalyst layers, more than 10 ion-conducting catalyst layers, more than 20 ion-conducting catalyst layers, more than 50 ion-conducting catalyst layers, etc. Similarly, the hybrid electrocatalyst layer of the present disclosure may include more than 2 non-ion-conducting catalyst layers, more than 5 non-ion-conducting catalyst layers, more than 10 non-ion-conducting catalyst layers, more than 20 non-ion-conducting catalyst layers, more than 50 non-ion-conducting catalyst layers, etc.

[0062] Each of the plurality of ion-conducting catalyst layers may include different amounts of ionomer and catalyst, such that a concentration gradient of the ionomer is formed. This concentration gradient may increase or decrease through the thickness of the hybrid electrocatalyst layer, i.e., in the direction from the ion-conducting polymer membrane 102 to one of the species diffusion / transport layers (also referred to herein as the "Z direction"). Alternatively, or in addition, the ionomer concentration gradient may increase or decrease along the length and / or width of the hybrid electrocatalyst layer, as shown in a cross-section of the hybrid electrocatalyst layer (also referred to herein as the "XY plane").

[0063] Likewise, each of the plurality of non-ion-conducting catalyst layers may include different amounts of non-conductive binder and catalyst, such that a concentration gradient of the non-conductive binder is formed. This concentration gradient may increase or decrease along the XY plane or along the Z direction as described above with respect to the ionomer concentration gradient.

[0064] Additionally or alternatively, the plurality of ion-conducting catalyst layers and non-ion-conducting catalyst layers may each have a porosity gradient in the Z direction or the XY plane. For example, the porosity of the hybrid electrocatalyst layer may increase or decrease along the Z direction or along the XY plane.

[0065] These concentration and porosity gradients have beneficial effects on the operation of electrochemical cells and can be tailored to meet the specific requirements of the cell.

[0066] The electrochemical cells of the present disclosure may be particularly suitable for use in electrolyzers, electrochemical hydrogen pumps, electrochemical cell-based ammonia synthesis, electrochemical cell-based CO2 electroreduction, and other applications.

[0067] When used in an electrolyzer, the cathode side of the electrochemical cell of the present disclosure can improve the reaction of oxygen diffused with hydrogen, thereby reducing oxygen reduction leading to the formation of peroxides and peroxide radicals. This avoids damage to the polymeric membrane and thus improves the life of the electrochemical cell.

[0068] When used in a hydrogen pump, the anode side of the electrochemical cell is more tolerant to hydrogen starvation. In the case where carbon monoxide is provided in the feed to the hydrogen pump, the hybrid electrocatalyst layer provides in situ carbon monoxide tolerance through chemical peroxidation. On both the anode and cathode sides, the outer layer of the electrochemical cell of the present disclosure improves the decomposition of peroxyl radicals.

[0069] When used in a gas / gas cell-based ammonia synthesis, the anode side of the electrochemical cell is similar to the hydrogen pump described above and is more tolerant to hydrogen starvation. On the cathode side, the outer layer of the electrochemical cell can be designed to draw out the synthesized ammonia by, for example, incorporating a Prussian blue analogue such as copper hexacyanoferrate or nickel hexacyanoferrate on the surface of the cation exchange membrane. This can be accomplished by adding a host material with an affinity for exchanging ammonium ions and releasing ammonia on the flow-field side.

[0070] When used in a gas / gas cell-based carbon dioxide electroreduction, the anode side of the electrochemical cell is similar to the hydrogen pump described above and is more tolerant to hydrogen starvation. On the cathode side, the outer layer of the electrochemical cell can be designed to carry out downstream reactions in situ. For example, carbon monoxide and hydrogen can react to form formaldehyde when catalyzed by a catalyst containing, for example, ruthenium or an alloy of ruthenium and nickel.

[0071] II. Processes for Fabricating Electrochemical Cells

[0072] Further provided herein are processes for making the electrochemical cells described above in Section 1. The processes can be used to make any of the electrochemical cells described in Section 1.

[0073] Now refer to Figure 2A The process 200 of the present disclosure includes the following steps: step 202 of coating an ion-conducting catalyst layer onto a transfer substrate (backing); step 204 of drying the ion-conducting catalyst layer on the transfer substrate to form an ion-conducting catalyst layer with the transfer substrate; step 206 of transferring the ion-conducting catalyst layer to an ion-conducting polymer membrane; step 208 of coating a non-ion-conducting catalyst layer on a mass diffusion / transport layer; step 210 of sintering the coated mass diffusion / transport layer to form a non-ion-conducting catalyst layer and a mass diffusion / transport layer; and step 212 of hot pressing the sintered layer onto the ion-conducting catalyst layer to form an electrochemical cell of the present disclosure. This process forms one hybrid electrocatalyst layer for one side of the electrochemical cell. Those skilled in the art will understand that the process can be repeated to form a hybrid electrocatalyst layer on the opposite side of the cell.

[0074] Although the numbers are arranged in sequence, those skilled in the art will understand that step 202, step 204, and step 206 can be performed before, after, or simultaneously with step 208 and step 210. Those skilled in the art will also understand that steps 202 and 204 can be repeated to form a hybrid electrocatalyst layer having multiple ion-conducting layers; similarly, steps 208 and 210 can be repeated to form a hybrid electrocatalyst layer having multiple non-ion-conducting catalyst layers.

[0075] In step 202, an ion-conducting catalyst layer is applied to a transfer substrate. The ion-conducting slurry includes an ionomer and an electrocatalyst dispersed in a solvent. The electrocatalyst and the ionomer are described in Section 1 above. The choice of solvent is not limited, as long as the solvent does not chemically react with the electrocatalyst or ionomer particles (which may hinder battery performance). For example, the solvent may include an alcohol-based solvent, such as ethylene glycol or glycerol. One of ordinary skill in the art will be able to select an appropriate solvent.

[0076] The transfer substrate may be a fiberglass layer coated with a polymer such as PTFE to allow easy peeling from the coated layer.

[0077] The coating can be accomplished by any method known in the art, such as dip coating, blade coating, spin coating, roller coating, rod coating, slot die coating, spray coating, ultrasonic spray coating, and other methods known in the art. In some embodiments, a 3D printable or inkjet coating method can be used to control the concentration and / or porosity of the ion conducting layer in the XY direction.

[0078] After the ion-conducting layer is applied to the transfer substrate, process 200 proceeds to step 204. In step 204, the ion-conducting catalyst layer applied to the transfer substrate is dried. The drying can be accomplished, for example, using an electric heater, a convection oven, or an infrared heater. The drying can be accomplished at an elevated temperature to rapidly evaporate the solvent. The drying temperature can be from about 80°C to about 120°C, for example, from about 100°C to about 120°C. The drying can be accomplished at atmospheric pressure or under vacuum. The drying can also be accomplished in an inert atmosphere.

[0079] Now go to Figure 2B , the ion-conducting slurry may include a pore-former composition to increase the porosity of the ion-conducting layer in the electrochemical cell. Pore-formers suitable for use in the present disclosure include polystyrene and polystyrene derivatives, polyethylene oxide and polyethylene oxide derivatives, polyvinylidene fluoride and polyvinylidene fluoride derivatives, carbon black, silica, polyacrylic acid, N-(2-hydroxypropyl)methacrylamide (HPMA), polyacrylamide (PAM), and combinations thereof. The pore-former may have an average particle diameter (particle diameter) of about 50 nm to about 1000 nm. The amount of pore-former included in the ion-conducting slurry will be related to the porosity of the ion-conducting layer. In embodiments where a pore-former is used, when the ion-conducting layer is dried in step 204, the process continues to step 205.

[0080] Step 205 includes removing the pore former from the ion conducting layer. Removal of the pore former is accomplished by immersing the ion conducting layer in a removal solvent that dissolves the pore former without dissolving or otherwise chemically reacting with the transfer substrate, the ionomer, or the catalyst. The removal solvent may include a polar organic solvent, a non-polar organic solvent, an aqueous solvent, or a combination thereof. In some examples, the removal solvent may include a hydrocarbon solvent, such as toluene or xylene (including m-xylene, o-xylene, and p-xylene), acetone, methanol, water, or the like. Alternatively, the pore former may be removed by heating the ion conducting layer to a temperature that causes the pore former to melt or evaporate without damaging the remaining structure.

[0081] Back to Figure 2A After the ion-conducting catalyst layer is dried, process 200 proceeds to step 206. Step 206 includes transferring the ion-conducting catalyst layer to an ion-conducting polymer membrane. The transferring step can be accomplished by hot pressing the ion-conducting catalyst layer onto the ion-conducting polymer membrane. The hot pressing causes the ion-conducting catalyst layer to adhere to the ion-conducting polymer membrane and also causes the transfer substrate to be peeled off from the ion-conducting layer. The hot pressing of step 206 can be performed at a temperature of about 80°C to about 140°C, for example, about 100°C to about 140°C, or about 125°C to about 140°C. The hot pressing can be performed at a pressure of about 70 psi to about 150 psi.

[0082] In step 208, a non-ion conductive slurry is applied to the material diffusion / transport layer. The material diffusion layer may be the material diffusion layer described in Section 1 above. The non-ion conductive slurry includes a non-ion conductive binder and an electrocatalyst dispersed in a solvent. The electrocatalyst and the non-ion conductive binder are described in Section 1 above. The choice of the solvent is not limited as long as the solvent does not chemically react with the electrocatalyst or non-ion conductive binder particles (which may hinder battery performance). For example, the solvent may include an alcohol-based solvent, such as ethylene glycol or glycerol. One of ordinary skill in the art will be able to select an appropriate solvent.

[0083] The coating can be accomplished by any method known in the art, such as dip coating, knife coating, spin coating, roller coating, rod coating, slot die coating, spray coating, ultrasonic spray coating, and other methods known in the art. In some embodiments, a 3D printable or inkjet coating method can be used to control the concentration and / or porosity of the non-ion-conducting catalyst layer in the XY direction.

[0084] After the non-ion conductive catalyst layer is coated onto the material diffusion / transport layer, process 200 proceeds to step 210. In step 210, the non-ion conductive catalyst layer coated on the material diffusion layer is sintered. The sintering can be performed using methods and equipment known in the art, such as heating in a convection oven or infrared heating. The sintering can be performed at an elevated temperature, such as about 300°C to about 400°C. Preferably, the sintering is performed above the glass transition temperature of the non-ion conductive binder. The sintering step is critical because, if not sintered, the non-ion conductive binder particles may peel off or break off from the non-ion conductive catalyst layer. The sintering improves the adhesive and cohesive properties of the particles and increases the durability of the non-ion conductive catalyst layer. The sintering can also be performed in an inert atmosphere.

[0085] Now go to Figure 2B , the non-ion conductive slurry may include a pore former composition to increase the porosity of the non-ion conductive catalyst layer in the electrochemical cell. Suitable pore formers for use are described above. The amount of pore former included in the non-ion conductive slurry will be related to the porosity of the non-ion conductive catalyst layer. In embodiments where a pore former is used, when the non-ion conductive catalyst layer is sintered in step 210, the process continues to step 211. Step 211 includes removing the pore former from the non-ion conductive catalyst layer. Removal of the pore former is accomplished by immersing the non-ion conductive catalyst layer in a removal solvent that is capable of dissolving the pore former without dissolving or otherwise chemically reacting with the transfer substrate, the non-ion conductive adhesive, or the catalyst. Suitable removal solvents for use are described above.

[0086] Back to Figure 2A After sintering the non-ion-conducting catalyst layer, process 200 proceeds to step 212. Step 212 includes hot pressing the sintered layer onto the ion-conducting catalyst layer that was transferred to the ion-conducting polymer membrane in step 206. The hot pressing in step 212 can be performed at a temperature of about 80° C. to about 140° C., for example, about 100° C. to about 140° C., or about 125° C. to about 140° C. The hot pressing can be performed at a pressure of about 70 psi to about 150 psi.

[0087] As described above, process 200 may be repeated to form the opposite side of the electrochemical cell.

[0088] Now refer to Figure 3A, describing another process 300 of the present disclosure. Process 300 includes: step 302 of coating a non-ion-conducting slurry on a mass diffusion / transport layer; step 304 of sintering the coated mass diffusion layer; step 306 of coating a sodium-type ion-conducting layer on a transfer layer; step 308 of drying the ion-conducting catalyst layer; and step 310 of transferring the ion-conducting catalyst layer to a sodium-type ion-conducting polymer membrane. Those skilled in the art will also understand that steps 302 and 304 can be repeated to form a hybrid electrocatalyst layer having multiple non-ion-conducting catalyst layers; similarly, steps 306 and 308 can be repeated to form a hybrid electrocatalyst layer having multiple ion-conducting catalyst layers.

[0089] In step 302, a non-ion conductive slurry is applied to the transfer layer. The material diffusion / transport layer may be the material diffusion / transport layer described in Section 1 above. The non-ion conductive slurry includes a non-ion conductive binder and an electrocatalyst dispersed in a solvent. The electrocatalyst and non-ion conductive binder are described in Section 1 above. The choice of solvent is not limited, as long as the solvent does not chemically react with the electrocatalyst or non-ion conductive binder particles (which may hinder battery performance). Those skilled in the art will be able to select an appropriate solvent.

[0090] The coating can be accomplished by any method known in the art, such as dip coating, knife coating, spin coating, roller coating, rod coating, slot die coating, spray coating, ultrasonic spray coating, and other methods known in the art. In some embodiments, a 3D printable or inkjet coating method can be used to control the concentration and / or porosity of the non-ion-conducting catalyst layer in the XY direction.

[0091] After the non-ion-conducting catalyst layer is applied to the transfer layer, process 300 proceeds to step 304. In step 304, the non-ion-conducting catalyst layer applied to the material diffusion layer is sintered. The sintering can be performed using methods and equipment known in the art, such as heating in a convection oven or infrared heating. The sintering can be performed at an elevated temperature, such as about 300° C. to about 400° C. The sintering improves the adhesion and cohesion of the particles and increases the durability of the non-ion-conducting catalyst layer. The sintering can also be performed in an inert atmosphere.

[0092] Now go to Figure 3B, the non-ion conductive slurry may include a pore former composition to increase the porosity of the non-ion conductive catalyst layer in the electrochemical cell. Suitable pore formers for use are described above. The amount of pore former included in the non-ion conductive slurry will be related to the porosity of the non-ion conductive catalyst layer. In embodiments where a pore former is used, when the non-ion conductive catalyst layer is sintered in step 304, the process continues to step 305. Step 305 includes removing the pore former from the non-ion conductive catalyst layer. Removal of the pore former is accomplished by immersing the non-ion conductive catalyst layer in a removal solvent that is capable of dissolving the pore former without dissolving or otherwise chemically reacting with the transfer layer, the non-ion conductive adhesive, or the catalyst. Suitable removal solvents for use are described above.

[0093] Now back Figure 3A At step 306, a sodium-type ion-conducting slurry is applied to the sintered material diffusion / transport layer formed in step 304. The sodium-type ion-conducting slurry includes a sodium-type ionomer and an electrocatalyst dispersed in a solvent. The electrocatalyst and the sodium-type ionomer are described in Section I above.

[0094] The coating can be accomplished by any method known in the art, such as dip coating, knife coating, spin coating, roller coating, rod coating, slot die coating, spray coating, ultrasonic spray coating, and other methods known in the art. In some embodiments, a 3D printable or inkjet coating method can be used to control the concentration and / or porosity of the ion-conducting layer in the XY direction.

[0095] Then, at step 308, the ion-conducting catalyst layer is dried so that it adheres to the non-ion-conducting catalyst layer. The drying can be performed, for example, using an oven. The drying can be performed at an elevated temperature, for example, from about 60°C to about 125°C, such as from about 80°C to about 125°C, or from about 100°C to about 125°C. The drying can be performed at atmospheric pressure or under vacuum. The drying can also be performed in an inert atmosphere.

[0096] Now go to Figure 3B, the ion conductive slurry may include a pore former composition to increase the porosity of the non-ion conductive catalyst layer in the electrochemical cell. Suitable pore formers for use are described above. The amount of pore former included in the non-ion conductive slurry is related to the porosity of the non-ion conductive catalyst layer. In embodiments where a pore former is used, when the ion conductive layer is dried in step 308, the process continues to step 309. Step 309 includes removing the pore former from the ion conductive layer. Removal of the pore former is accomplished by immersing the ion conductive layer in a removal solvent that is capable of dissolving the pore former without dissolving or otherwise chemically reacting with the transfer substrate, the ionomer, or the catalyst. Suitable removal solvents for use are described above.

[0097] Back to Figure 3A At step 310, the ion-conducting catalyst layer and the non-ion-conducting catalyst layer are transferred to an ion-conducting polymer membrane. The transfer step can be accomplished by hot pressing the ion-conducting layer onto the ion-conducting polymer membrane. The hot pressing can adhere the ion-conducting layer to the ion-conducting polymer membrane and also peel the transfer substrate from the non-ion-conducting catalyst layer. The hot pressing can be performed at a temperature of about 80°C to about 140°C, for example, about 100°C to about 140°C, or about 125°C to about 140°C. The hot pressing can be performed at a pressure of about 70 psi to about 150 psi.

[0098] Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is understood that such range format is used only for convenience and brevity and should be interpreted flexibly to include not only the values ​​explicitly recited as range limits, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly recited. As an illustration, a numerical range of "about 2 to about 50" should be interpreted to include not only the explicitly recited values ​​of 2 to 50, but also all individual values ​​and subranges within the specified range. Thus, included in this numerical range are individual values ​​such as 2, 2.4, 3, 3.7, 4, 5.5, 10, 10.1, 14, 15, 15.98, 20, 20.13, 23, 25.06, 30, 35.1, 38.0, 40, 44, 44.6, 45, 48, and subranges such as 1-3, 2-4, 5-10, 5-20, 5-25, 5-30, 5-35, 5-40, 5-50, 2-10, 2-20, 2-30, 2-40, 2-50, etc. The same principle applies to ranges that describe only one numerical value as a minimum or maximum. Furthermore, such an interpretation should apply regardless of the width of the described range or the described characteristics.

[0099] As used herein, the term "about" is used to provide flexibility for numerical range endpoints by indicating that a given value may be "slightly above" or "slightly below" the endpoint. For example, the endpoint may vary from the listed value by no more than 10%, 8%, 5%, 3%, 2%, or 1%. Furthermore, for convenience and brevity, and in another example, a numerical range of "about 50 mg / mL to about 80 mg / mL" should also be understood to provide support for a range of "50 mg / mL to 80 mg / mL."

[0100] As used herein, the terms "including," "comprising," and / or "having" are understood to mean "comprising" and are open-ended terms.

[0101] As used herein, the indefinite articles "a" and "an" in the specification and claims should be understood to mean "at least one" unless explicitly indicated to the contrary.

[0102] The enumerated embodiments

[0103] Embodiment 1: A process for manufacturing an electrochemical cell, comprising:

[0104] applying an ion conductive slurry onto the transfer layer;

[0105] drying the ion-conducting slurry to form an ion-conducting layer;

[0106] transferring the ion-conducting layer from the transfer layer to an ion-conducting polymer membrane;

[0107] coating a non-ion conductive slurry onto the mass diffusion / transport layer to form a coated mass diffusion / transport layer;

[0108] sintering the coated diffusion layer to form a non-ion-conducting catalyst layer on the species diffusion / transport layer; and

[0109] The non-ion-conducting catalyst layer is hot pressed onto the ion-conducting layer.

[0110] Embodiment 2: The process of embodiment 1, wherein the sintering is performed at a temperature of about 300°C to about 400°C.

[0111] Embodiment 3: The process of Embodiment 1 or 2, wherein the ion conductive slurry comprises a solvent, an ionomer, and an electrocatalyst.

[0112] Embodiment 4: The process of any one of Embodiments 1-3, wherein the non-ion conductive slurry comprises a solvent, a non-ion conductive binder, and an electrocatalyst.

[0113] Embodiment 5: The process of any one of Embodiments 1-4, wherein the hot pressing is performed at a pressure of about 70 psi to about 150 psi and a temperature of about 80°C to about 140°C.

[0114] Embodiment 6: The process of any one of Embodiments 1-5, wherein the transfer layer comprises a fiberglass layer coated with polytetrafluoroethylene.

[0115] Embodiment 7: The process of any one of Embodiments 1-6, wherein the ion-conducting polymer membrane comprises a perfluorosulfonic acid-based polymer.

[0116] Embodiment 8: The process of any one of Embodiments 1-7, wherein the ion conductive slurry further comprises a pore former.

[0117] Embodiment 9: The process of embodiment 8, further comprising removing the pore former from the ion conducting layer before transferring the ion conducting layer from the transfer layer to the ion conducting polymer membrane.

[0118] Embodiment 10: The process of any one of Embodiments 1-9, wherein the non-ion conductive slurry further comprises a pore former.

[0119] Embodiment 11: The process of Embodiment 10, further comprising removing the pore former from the non-ion-conducting catalyst layer before hot pressing the non-ion-conducting catalyst layer onto the ion-conducting layer.

[0120] Embodiment 12: An electrochemical cell manufactured by the process of claim 1, comprising:

[0121] an ion-conducting polymer membrane having a first surface and a second surface;

[0122] a first hybrid electrocatalyst layer having a first surface and a second surface, the first surface of the first hybrid electrocatalyst layer being in contact with the first surface of the ion-conducting polymer membrane, the first hybrid electrocatalyst layer comprising:

[0123] a first ion-conducting layer; and

[0124] a first non-ion-conducting catalyst layer;

[0125] a first mass diffusion / transport layer in contact with the second surface of the first hybrid electrocatalyst layer, wherein the first mass diffusion / transport layer is in contact with the first non-ion-conducting catalyst layer, and the ion-conducting polymer membrane is in contact with the first ion-conducting layer;

[0126] a second hybrid electrocatalyst layer having a first surface and a second surface, the first surface of the second hybrid electrocatalyst layer being in contact with the second surface of the ion-conducting polymer membrane, the second hybrid electrocatalyst layer comprising:

[0127] a second ion conducting layer; and

[0128] a second non-ion-conducting catalyst layer; and

[0129] a second species diffusion / transport layer in contact with the second surface of the second hybrid electrocatalyst layer, wherein the second species diffusion / transport layer is in contact with the second non-ion-conducting catalyst layer, and the ion-conducting polymer membrane is in contact with the second ion-conducting layer.

[0130] Embodiment 13: The electrochemical cell of Embodiment 12, wherein the electrochemical cell is suitable for use in an electrolyzer, a hydrogen pump, ammonia synthesis based on a gas / gas cell, or carbon dioxide electroreduction based on a gas / gas cell.

[0131] Embodiment 14: The electrochemical cell of Embodiment 12 or 13, wherein the first ion conducting layer, the second ion conducting layer, or both the first ion conducting layer and the second ion conducting layer comprise a plurality of ion conducting layers.

[0132] Embodiment 15: The electrochemical cell of any one of Embodiments 12-14, wherein the plurality of ion conducting layers defines a concentration gradient of ionomer along a thickness of the plurality of ion conducting layers.

[0133] Embodiment 16: The electrochemical cell of Embodiment 14, wherein the plurality of ion conducting layers defines a porosity gradient along the thickness of the plurality of ion conducting layers.

[0134] Embodiment 17: The electrochemical cell of any one of Embodiments 12-16, wherein the ion-conducting polymer membrane is a sodium-type ion-conducting polymer membrane.

[0135] Embodiment 18: The electrochemical cell of any of Embodiments 12-17, wherein the first ion conducting layer and the second ion conducting layer each comprise an ionomer.

[0136] Embodiment 19: The electrochemical cell of Embodiment 18, wherein the ionomer is a sodium-type ionomer.

[0137] Embodiment 20: A process for making an electrochemical cell, comprising:

[0138] applying a non-ion conductive slurry onto the transfer layer;

[0139] sintering the coated transfer layer to form a non-ion-conductive catalyst layer on the transfer layer;

[0140] applying a sodium-type ion-conductive slurry comprising a sodium-type ionomer onto the non-ion-conductive catalyst layer;

[0141] drying the ion-conducting slurry to form a hybrid electrocatalyst layer comprising an ion-conducting layer and a non-ion-conducting catalyst layer; and

[0142] The hybrid electrocatalyst layer is hot pressed onto a sodium-type ion-conducting polymer membrane.

[0143] Embodiment 21: The process of Embodiment 20, wherein the sintering is performed at a temperature of about 300°C to about 400°C.

[0144] Embodiment 22: The process of Embodiment 20 or 21, wherein the ion conductive slurry further comprises a solvent and an electrocatalyst.

[0145] Embodiment 23: The process of any one of Embodiments 20-22, wherein the non-ion conductive slurry comprises a solvent, a non-ion conductive binder, and an electrocatalyst.

[0146] Embodiment 24: The process of any one of Embodiments 20-23, wherein the hot pressing is performed at a pressure of about 70 psi to about 150 psi and a temperature of about 80°C to about 140°C.

[0147] Embodiment 25: The process of any one of Embodiments 20-24, wherein the transfer layer comprises a fiberglass layer coated with polytetrafluoroethylene.

[0148] Embodiment 26: The process of any one of Embodiments 20-25, wherein the sodium-form ion-conducting polymer membrane comprises a sodium-form perfluorosulfonic acid-based polymer.

[0149] Embodiment 27: The process of any one of Embodiments 20-26, wherein the ion conductive slurry further comprises a pore former.

[0150] Embodiment 28: The process of Embodiment 27, further comprising removing the pore former from the ion conducting layer before transferring the ion conducting layer from the transfer layer to the ion conducting polymer membrane.

[0151] Embodiment 29: The process of any one of Embodiments 20-28, wherein the non-ionically conductive slurry further comprises a pore former.

[0152] Embodiment 30: The process of Embodiment 29, further comprising removing the pore former from the non-ion-conducting catalyst layer before hot pressing the non-ion-conducting catalyst layer onto the ion-conducting layer.

[0153] Embodiment 31: A process for making an electrochemical cell, comprising:

[0154] applying a non-ion conductive slurry onto the transfer layer;

[0155] sintering the coated transfer layer to form a non-ion-conductive catalyst layer on the transfer layer;

[0156] applying a sodium-type ion-conductive slurry comprising a sodium-type ionomer and a pore-forming agent onto the non-ion-conductive catalyst layer;

[0157] drying the ion-conducting slurry to form a hybrid electrocatalyst layer comprising an ion-conducting layer and a non-ion-conducting catalyst layer; and

[0158] The hybrid electrocatalyst layer is hot pressed onto a sodium-type ion-conducting polymer membrane.

[0159] Embodiment 32: The process of Embodiment 31, wherein the sintering is performed at a temperature of about 300°C to about 400°C.

[0160] Embodiment 33: The process of Embodiment 31 or 32, wherein the ion conductive slurry further comprises a solvent and an electrocatalyst.

[0161] Embodiment 34: The process of any one of Embodiments 31-33, wherein the non-ionically conductive slurry comprises a solvent, a non-ionically conductive binder, and an electrocatalyst.

[0162] Embodiment 35: The process of any one of Embodiments 31-34, wherein the hot pressing is performed at a pressure of about 70 psi to about 150 psi and a temperature of about 80°C to about 140°C.

[0163] Embodiment 36: The process of any one of Embodiments 31-35, wherein the transfer layer comprises a fiberglass layer coated with polytetrafluoroethylene.

[0164] Embodiment 37: The process of any one of Embodiments 31-36, wherein the sodium-form ion-conducting polymer membrane comprises a sodium-form perfluorosulfonic acid-based polymer.

[0165] Embodiment 38: The process of any one of Embodiments 31-37, further comprising removing the pore former from the ion-conducting layer before transferring the ion-conducting layer from the transfer layer to the ion-conducting polymer membrane.

[0166] Embodiment 39: The process of any one of Embodiments 31-38, wherein the non-ionically conductive slurry further comprises a pore former.

[0167] Embodiment 40: The process of Embodiment 39, further comprising removing the pore former from the non-ion-conducting catalyst layer before hot pressing the non-ion-conducting catalyst layer onto the ion-conducting layer.

[0168] Embodiment 41: A process for making an electrochemical cell, comprising:

[0169] applying a non-ion conductive slurry onto the transfer layer, the non-ion conductive slurry including a pore former;

[0170] sintering the coated transfer layer to form a non-ion-conductive catalyst layer on the transfer layer;

[0171] applying a sodium-type ion-conductive slurry comprising a sodium-type ionomer onto the non-ion-conductive catalyst layer;

[0172] drying the ion-conducting slurry to form a hybrid electrocatalyst layer comprising an ion-conducting layer and a non-ion-conducting catalyst layer; and

[0173] The hybrid electrocatalyst layer is hot pressed onto a sodium-type ion-conducting polymer membrane.

[0174] Embodiment 42: The process of Embodiment 41, wherein the sintering is performed at a temperature of about 300°C to about 400°C.

[0175] Embodiment 43: The process of Embodiment 41 or 42, wherein the ion conductive slurry further comprises a solvent and an electrocatalyst.

[0176] Embodiment 44: The process of any one of Embodiments 41-43, wherein the non-ionically conductive slurry comprises a solvent, a non-ionically conductive binder, and an electrocatalyst.

[0177] Embodiment 45: The process of any one of Embodiments 41-44, wherein the hot pressing is performed at a pressure of about 70 psi to about 150 psi and a temperature of about 80°C to about 140°C.

[0178] Embodiment 46: The process of any one of Embodiments 41-45, wherein the transfer layer comprises a fiberglass layer coated with polytetrafluoroethylene.

[0179] Embodiment 47: The process of any one of Embodiments 41-46, wherein the sodium-form ion-conducting polymer membrane comprises a perfluorosulfonic acid-based polymer in the sodium form.

[0180] Embodiment 48: The process of any one of Embodiments 41-47, wherein the ion conductive slurry further comprises a pore former.

[0181] Embodiment 49: The process of Embodiment 48, further comprising removing the pore former from the ion conducting layer before transferring the ion conducting layer from the transfer layer to the ion conducting polymer membrane.

[0182] Embodiment 50: The process of any one of Embodiments 41-49, further comprising removing the pore former from the non-ion-conducting catalyst layer before hot pressing the non-ion-conducting catalyst layer onto the ion-conducting layer.

Claims

1. A process for manufacturing an electrochemical cell comprising: applying an ion conductive slurry onto the transfer layer; drying the ion-conducting slurry to form an ion-conducting layer; transferring the ion-conducting layer from the transfer layer to an ion-conducting polymer membrane; coating a non-ion conductive slurry onto the mass diffusion / transport layer to form a coated mass diffusion / transport layer, wherein the non-ion conductive slurry comprises a solvent, a non-ion conductive binder, and an electrocatalyst; sintering the coated diffusion layer to form a non-ion-conducting catalyst layer on the species diffusion / transport layer; and The non-ion-conducting catalyst layer is hot pressed onto the ion-conducting layer.

2. The process of claim 1 , wherein the sintering is performed at a temperature of about 300° C. to about 400° C.

3. The process of claim 1, wherein the ion conductive slurry comprises a solvent, an ionomer, and an electrocatalyst.

4. The process of claim 1, wherein the hot pressing is performed at a pressure of about 70 psi to about 150 psi and a temperature of about 80°C to about 140°C.

5. The process of claim 1 wherein the transfer layer comprises a fiberglass layer coated with polytetrafluoroethylene.

6. The process of claim 1 wherein the ion-conducting polymer membrane comprises a perfluorosulfonic acid-based polymer.

7. The process of claim 1, wherein the ion conductive slurry further comprises a pore former.

8. The process of claim 7, further comprising removing the pore former from the ion conducting layer before transferring the ion conducting layer from the transfer layer to the ion conducting polymer membrane.

9. The process of claim 1, wherein the non-ionically conductive slurry further comprises a pore former.

10. The process of claim 9, further comprising removing the pore former from the non-ion-conducting catalyst layer before hot pressing the non-ion-conducting catalyst layer onto the ion-conducting layer.

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