Membrane electrode assembly for a water electrolyser and water electrolyser comprising the same

Abstract

Provided is a membrane-electrode assembly for a water electrolyzer, including: a polymer electrolyte membrane having an active area and a non-active area surrounding the active area; a hydrogen-producing electrode located on a first surface of the active area of the polymer electrolyte membrane; an oxygen-producing electrode located on a second surface of the active area of the polymer electrolyte membrane; a first sub-gasket disposed on a first surface of the non-active area of the polymer electrolyte membrane and surrounding the hydrogen-producing electrode; and a second sub-gasket disposed on a second surface of the non-active area of the polymer electrolyte membrane and surrounding the oxygen-producing electrode, wherein the first sub-gasket has a first window accommodating the hydrogen-producing electrode, and a first water supply path surrounding the first window and exposing the non-active area of the polymer electrolyte membrane.

Description

Technical Field

[0001] The present invention relates to a membrane electrode assembly for a water electrolyzer and a water electrolyzer including the membrane electrode assembly. Background Technology

[0002] Due to the increasing demand for alternative energy sources to fossil fuels, and the growing focus on efficient, inexpensive, and environmentally friendly energy conversion or storage systems, fuel production via water electrolysis is receiving widespread attention as a significant alternative with high commercial potential, considering both environmental and energy issues. Water electrolysis is a technology that produces hydrogen and oxygen by electrochemically splitting water.

[0003] In the polymer electrolyte membrane electrolyzer (PEMWE), the membrane electrode assembly (MEA) that actually generates hydrogen has the following structure: an electrode that undergoes the oxygen evolution reaction (OER), i.e., the oxygen evolution reaction electrode, and an electrode that undergoes the hydrogen evolution reaction (HER), i.e., the hydrogen evolution reaction electrode, are provided with a polymer electrolyte membrane comprising a cationic conductive polymer or an anionic conductive polymer.

[0004] In a polymer electrolyte membrane water electrolysis cell, the oxygen-producing electrode is in contact with water, while the hydrogen-producing electrode is not humidified separately. Therefore, the water content of the polymer electrolyte membrane has a concentration gradient in the thickness direction.

[0005] As the water content of the polymer electrolyte membrane increases, its ionic conductivity also increases. Therefore, in polymer electrolyte membrane water electrolyzers, the low water content of the hydrogen-producing electrode presents a limitation. Furthermore, when the polymer electrolyte membrane water electrolyzer operates at high current or high voltage, heat generation may occur, and temperature control can be difficult when this occurs. Summary of the Invention

[0006] Technical issues

[0007] One aspect of this disclosure provides a membrane electrode assembly for a water electrolyzer that can increase the water content of the polymer electrolyte membrane by directly supplying water to the polymer electrolyte membrane, thereby increasing the ionic conductivity of the polymer electrolyte membrane, and additionally cooling the membrane electrode assembly to reduce the energy required, thereby maximizing the performance of the water electrolyzer.

[0008] Technical solution

[0009] According to one aspect, a membrane electrode assembly for a water electrolyzer includes: a polymer electrolyte membrane having an active region and an inactive region surrounding the active region; a hydrogen-producing electrode located on a first surface of the active region of the polymer electrolyte membrane; an oxygen-producing electrode located on a second surface of the active region of the polymer electrolyte membrane; a first sub-pad disposed on the first surface of the inactive region of the polymer electrolyte membrane and surrounding the hydrogen-producing electrode; and a second sub-pad disposed on the second surface of the inactive region of the polymer electrolyte membrane and surrounding the oxygen-producing electrode, wherein the first sub-pad has a first window for receiving the hydrogen-producing electrode and a first water supply path surrounding the first window and exposing the inactive region of the polymer electrolyte membrane.

[0010] The first window can penetrate the first sub-pad to expose the hydrogen-producing electrode.

[0011] The first water supply path can penetrate the first sub-gasket to expose the inactive area of ​​the polymer electrolyte membrane.

[0012] The first window and the first water supply path can be hollow.

[0013] The first water supply path can be extended to surround the four sides of the first window.

[0014] One end of the first water supply path and the other end may not intersect and may be spaced apart from each other.

[0015] The second sub-pad may have a second window for accommodating the oxygen-generating electrode.

[0016] The second sub-pad may not have a water supply path that exposes the inactive area of ​​the polymer electrolyte membrane.

[0017] The oxygen-generating electrode may include a noble metal oxide catalyst, which comprises iridium oxide, oxides of iridium alloys, or combinations thereof.

[0018] The membrane electrode assembly for a water electrolyzer may further include: a first gas diffusion layer located on the hydrogen production electrode; and a second gas diffusion layer located on the oxygen production electrode.

[0019] The first gas diffusion layer may include conductive porous components, including carbon paper, carbon cloth, carbon felt, metal paper, metal cloth, metal felt, or combinations thereof.

[0020] The second gas diffusion layer may include multiple fibers integrated in the form of multiple pores, and the multiple fibers may include metal oxides or metals.

[0021] The membrane electrode assembly for a water electrolysis cell may further include: a first pad disposed on the first sub-pad and surrounding the first gas diffusion layer; and a second pad disposed on the second sub-pad and surrounding the second gas diffusion layer.

[0022] The first gasket may have a third window that accommodates the first gas diffusion layer, and a third water supply path that surrounds the third window and exposes the first water diffusion layer.

[0023] According to one aspect, a water electrolysis cell includes: the membrane electrode assembly described above; a first partition located on a first surface of the membrane electrode assembly; and a second partition located on a second surface of the membrane electrode assembly, wherein the first partition has a flow channel located in a region corresponding to the hydrogen production electrode, and a water channel surrounding the first flow channel and located in a region corresponding to the first water supply path.

[0024] The water channel can extend to surround the four sides of the flow channel.

[0025] One end and the other end of the water channel can be spaced apart from each other without intersecting.

[0026] One end of the water channel may have a water inlet.

[0027] The other end of the water channel may have a water outlet.

[0028] The area ratio of the water channel to the total area of ​​the first separator can be from 10% to 80%.

[0029] The depth ratio of the water channel to the total thickness of the first separator can be from 5% to 40%.

[0030] The water electrolysis cell may further include: a first gas diffusion layer located on the hydrogen-producing electrode; and a second gas diffusion layer located on the hydrogen-producing electrode.

[0031] The second gas diffusion layer comprises multiple fibers integrated in the form of multiple pores, and the multiple fibers may comprise metal oxides or metals.

[0032] The water electrolysis cell may further include: a first gasket disposed on the first sub-gasket and surrounding the first gas diffusion layer; and a second gasket disposed on the second sub-gasket and surrounding the second gas diffusion layer.

[0033] The first gasket may have a third window that accommodates the first gas diffusion layer, and a third water supply path that surrounds the third window and exposes the first water diffusion layer.

[0034] Beneficial effects

[0035] According to one aspect, the membrane electrode assembly for a water electrolyzer can directly supply water to the polymer electrolyte membrane to increase the water content of the polymer electrolyte membrane, thereby increasing the ionic conductivity of the polymer electrolyte membrane, and additionally cool the membrane electrode assembly to reduce the energy required, thereby maximizing the performance of the water electrolyzer. Attached Figure Description

[0036] Figure 1 This is a cross-sectional view of a membrane electrode assembly according to one embodiment.

[0037] Figure 2 It is based on Figure 1 A plan view of the membrane electrode assembly.

[0038] Figure 3 This is a cross-sectional view of a membrane electrode assembly according to one embodiment.

[0039] Figure 4 It is based on Figure 3 A plan view of the membrane electrode assembly.

[0040] Figure 5 This is a cross-sectional view of a membrane electrode assembly according to one embodiment.

[0041] Figure 6 It is based on Figure 5 A plan view of the membrane electrode assembly.

[0042] Figure 7 It is a cross-sectional view of a water electrolysis cell according to one implementation plan.

[0043] Figure 8 yes Figure 7 The plan view of the separator shown illustrates the surface facing the membrane electrode assembly. Detailed Implementation

[0044] The advantages and features of the techniques described below, as well as the methods of implementing them, will become clear from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the forms of implementation may not be limited to those disclosed below. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in the sense that are commonly understood by one of ordinary skill in the art. Furthermore, unless explicitly defined, terms defined in common dictionaries should not be idealized or over-interpreted.

[0045] Throughout the specification, when a part “includes” or “contains” an element, unless otherwise specifically stated, it means that other elements may be further included or contained, rather than excluding other elements.

[0046] In the following, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the embodiments described below are provided for illustrative purposes only to aid in a clear understanding of the present disclosure and do not limit the scope of the present disclosure.

[0047] Figure 1 This is a cross-sectional view of a membrane electrode assembly according to one embodiment. Figure 2 It is based on Figure 1 A plan view of the membrane electrode assembly.

[0048] Reference Figure 1 and Figure 2 The membrane electrode assembly for a water electrolysis cell includes a polymer electrolyte membrane 110, a hydrogen generation electrode 121 located on a first surface of the polymer electrolyte membrane 110, an oxygen generation electrode 122 located on a second surface of the polymer electrolyte membrane 110 (a surface on the opposite side of the first surface), a first sub-pad 131 located on the first surface of the polymer electrolyte membrane 110, and a second sub-pad 132 located on the second surface of the polymer electrolyte membrane 110.

[0049] For example, the polymer electrolyte membrane 110 may include a porous support containing multiple pores and an ion conductor filling the internal pores of the porous support.

[0050] As an example, porous supports may comprise highly fluorinated polymers, such as perfluorinated polymers, that exhibit excellent resistance to thermal and chemical decomposition. For instance, the porous support may be polytetrafluoroethylene (PTFE) or a mixture of PTFE and CF2=CFC. n F 2n+1 (n is an integer from 1 to 5) or CF2 = CFO - (CF2CF(CF3)O) m C n F 2n+1 (m is an integer from 0 to 15, and n is an integer from 1 to 15) copolymers.

[0051] As an example of a porous support, a porous support can be a nonwoven fiber web composed of multiple randomly oriented fibers.

[0052] Nonwoven fiber webs are sheets with an interwoven structure of individual fibers or filaments, but not in the same way as woven fabrics. Nonwoven fiber webs can be manufactured by methods including carding, stretching, air-forming, wet-forming, meltblowing, spunbonding, or stitch-bonding.

[0053] As another example of a porous support in the form of a nonwoven fiber web, a porous support may include a nanoweb, wherein the nanofibers are integrated in the form of a nonwoven fabric comprising multiple pores.

[0054] For nanofibers, hydrocarbon polymers that exhibit excellent chemical resistance and hydrophobicity, thus eliminating concerns about morphological deformation due to moisture in high-humidity environments, can be used. For example, hydrocarbon polymers may include nylon, polyimide, polyarylamide, polyetherimide, polyacrylonitrile, polyaniline, polyethylene oxide, polyethylene naphthalate, polybutylene terephthalate, styrene-butadiene rubber, polystyrene, polyvinyl chloride, polyvinyl alcohol, polyvinylidene fluoride, polyethylene butene, polyurethane, polybenzoxazole, polybenzimidazole, polyamide-imide, polyethylene terephthalate, polyphenylene sulfide, polyethylene, polypropylene, copolymers thereof, or combinations thereof, and polyimide with superior heat resistance, chemical resistance, and morphological stability may be used.

[0055] The porosity of the porous support can be greater than or equal to 45%, and for example, greater than or equal to 60%. Simultaneously, the porous support can have a porosity less than or equal to 90%. If the porosity of the porous support is greater than 90%, the form stability decreases, and subsequent processes may not proceed smoothly. The porosity can be calculated using Equation 1 below, as the ratio of the air volume to the total volume of the porous support. In this case, the total volume can be calculated by preparing a rectangular sample and measuring its width, length, and thickness, while the air volume can be obtained by measuring the mass of the sample and then subtracting the polymer volume calculated from the density from the total volume.

[0056] [Formula 1]

[0057] Porosity (%) = (Air volume in the porous support / Total volume of the porous support) x 100

[0058] For example, the polymer electrolyte membrane 110 may be a polymer electrolyte membrane in the form of an enhanced composite membrane in which ion conductors are filled in the internal pores of a porous support.

[0059] At this point, the polymer electrolyte membrane 110 may further include a first ion conductor layer located on one surface of the porous support and a second ion conductor layer located on the other surface of the porous support. The first and second ion conductor layers may be formed such that, after filling the internal pores of the porous support, the remaining ion conductors form a thin film on the surface of the porous support.

[0060] An ionic conductor may include a main chain, side chains branching from the main chain, and ion-exchange groups substituted in the side chains.

[0061] For example, the ion conductor can contain cation exchange groups. That is, the polymer electrolyte membrane 110 can be used in a proton exchange membrane electrolysis (PEMWE) cell.

[0062] In a proton exchange membrane water electrolysis cell, water is supplied toward the oxygen-producing electrode 122, where hydrogen ions (H+) are produced.+ It moves toward the hydrogen production electrode 121 through the polymer electrolyte membrane 110.

[0063] For example, the cation exchange groups contained in the ionic conductor may include sulfonic acid group, ethylbenzenesulfonic acid group, carboxyl group, boric acid group, phosphoric acid group, imide group, sulfonimide group, sulfonamide group, sulfonyl fluoride group or combinations thereof, such as sulfonic acid group.

[0064] For example, the backbone of an ionic conductor containing cation exchange groups may include poly(perfluorosulfonic acid), poly(perfluorocarboxylic acid), poly(tetrafluoroethylene), fluorinated polyarylene, polyimide (PI), polyarylene ether sulfone (PAES), polyarylene ether ketone, polyether ether ketone (PEEK), polybenzimidazole (PBI), polysulfone (PSU), polystyrene (PS), polyphosphazene, polyquinoxaline, polyketone, polyether sulfone, polyether ketone, polyphenylsulfone, polyphenylene sulfide, polyphenylene sulfide sulfone, polyphenylene sulfide sulfone nitrile, polyarylene ether nitrile, polyarylene ether ether nitrile, polyarylene ether sulfone nitrile, polyethylene, polyphenylene ether, polypyrrole, polythiophene, polycarbazole, polyaniline, polyindole, polypyrrole, or combinations thereof.

[0065] For example, the ion conductor can contain anion exchange groups. That is, the polymer electrolyte membrane 110 can be used in anion exchange membrane electrolysis (AEMWE) cells.

[0066] In an anion exchange membrane water electrolysis cell, water is supplied toward the hydrogen production electrode 121, where hydroxide ions (OH-) are produced. - It moves toward the oxygen-generating electrode 122 through the polymer electrolyte membrane 110.

[0067] For example, the anion exchange group contained in the ionic conductor may include ammonium, pyridinium, triazolyl, tetraalkylammonium, imidazolium, benzimidazolium, cyclic ammonium, or combinations thereof, such as ammonium.

[0068] For example, the backbone of an ionic conductor containing anion exchange groups may include polyphenylene ether, polyphenylene, polyfluorene, poly(arylpiperidinium), polynorbornene, polystyrene (PS), polybenzimidazole (PBI), polyphenylene sulfide, polysulfone (PSU), polyaryletherketone, polyethylene, polyphenylene ether, polypyrrole, polythiophene, polycarbazole, polyaniline, polyindole, polypyrrole, or combinations thereof.

[0069] Hydrogen-producing electrode 121 and oxygen-producing electrode 122 are aligned with each other and have a polymer electrolyte membrane 110 therebetween. The polymer electrolyte membrane 110 has an active region for transferring cations or anions between the hydrogen-producing electrode 121 and the oxygen-producing electrode 122 and an inactive region 110a surrounding the active region.

[0070] For example, the active region of the polymer electrolyte membrane 110 is the region that is in contact with the hydrogen generation electrode 121 and the oxygen generation electrode 122, while the inactive region 110a may be the region that is not in contact with the hydrogen generation electrode 121 and the oxygen generation electrode 122.

[0071] The hydrogen generation electrode 121 can be disposed on the first surface of the active region of the polymer electrolyte membrane 110, and the oxygen generation electrode 122 can be disposed on the second surface of the active region of the polymer electrolyte membrane 110.

[0072] The hydrogen production electrode 121 and the oxygen production electrode 122 may each include a catalyst layer.

[0073] For example, the catalyst layer may contain noble metal oxides. These noble metal oxides may be iridium oxide, oxides of iridium alloys, or combinations thereof. For instance, the noble metal oxide may be IrO. x (x is an integer from 1 to 3), IrMO x (M includes Ru, Pt, Sn, Se, Zn, Au, Te, Nb or combinations thereof, and x is an integer from 1 to 3) or combinations thereof.

[0074] For example, the catalyst layer may contain a noble metal, which may be a platinum-based noble metal. For instance, platinum-based noble metals may include platinum (Pt) and / or Pt-M alloys. M may include palladium (Pd), ruthenium (Ru), iridium (Ir), osmium (Os), gallium (Ga), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), silver (Ag), gold (Au), zinc (Zn), tin (Sn), molybdenum (Mo), tungsten (W), lanthanum (La), or rhodium (Rh). For example, Pt-M alloys may include Pt-Pd, Pt-Sn, Pt-Mo, Pt-Cr, Pt-W, Pt-Ru, Pt-Ni, Pt-Co, Pt-Y, Pt-Ru-W, Pt-Ru-Ni, Pt-Ru-Mo, Pt-Ru-Rh-Ni, Pt-Ru-Sn-W, Pt-Ru-Ir-Ni, Pt-Co-Mn, Pt-Co-Ni, Pt-Co-Fe, Pt-Co-Ir, Pt-Co-S, Pt-Co-P, Pt-Fe, Pt-Fe-Ir, Pt-Fe-S, Pt-Fe-P, Pt-Au-Co, Pt-Au-Fe, Pt-Au-Ni, Pt-Ni, Pt-Ni-Ir, Pt-Cr, Pt-Cr-Ir, or combinations thereof.

[0075] For example, the catalyst layer of the hydrogen production electrode 121 may contain a noble metal, which may include a platinum-based noble metal. The catalyst layer of the oxygen production electrode 122 may contain a noble metal oxide, which may include iridium oxide, oxides of iridium alloys, or combinations thereof.

[0076] The catalyst layer may further comprise a support for noble metal oxides or noble metals. Supports for noble metal oxides may be, for example, titanium dioxide (TiO2). Supports for noble metals may be carbon-based supports, such as graphite, super P, carbon fibers, carbon sheets, carbon black, Ketjen black, Denka black, acetylene black, carbon nanotubes (CNTs), carbon spheres, carbon ribbons, fullerenes, activated carbon, carbon nanofibers, carbon nanowires, carbon nanospheres, carbon nanoangles, carbon nanocages, carbon nanorings, ordered nano / mesoporous carbon, carbon aerogels, mesoporous carbon, graphene, stabilized carbon, activated carbon, or combinations thereof.

[0077] The catalyst layer may further include ionic conductors to improve adhesion and transport hydrogen ions. The description of the ionic conductors that may be included in the catalyst layer is the same as that described in the polymer electrolyte membrane 110, and therefore will be omitted. The ionic conductors included in the catalyst layer and the ionic conductors included in the polymer electrolyte membrane 110 may be the same or different.

[0078] The first sub-pad 131 can be disposed on the first surface of the inactive region 110a of the polymer electrolyte membrane 110, and the second sub-pad 132 can be disposed on the second surface of the inactive region 110a of the polymer electrolyte membrane 110.

[0079] The first sub-shield 131 and the second sub-shield 132 can prevent the edge portion of the polymer electrolyte membrane 110 from being damaged due to repeated expansion and contraction during the operation of the water electrolysis cell, improve the low operability of the membrane electrode assembly due to the extremely thin polymer electrolyte membrane 110, and prevent fluid (e.g., hydrogen or oxygen) leakage.

[0080] The first sub-gasket 131 and the second sub-gasket 132 each have a first window and a second window to accommodate the hydrogen-generating electrode 121 and the oxygen-generating electrode 122, and to expose the hydrogen-generating electrode 121 and the oxygen-generating electrode 122. For example, the first window may be a hole located in the central portion of the first sub-gasket 131 and penetrating the first sub-gasket 131 in the thickness direction. Similarly, the second window may be a hole located in the central portion of the second sub-gasket 132 and penetrating the second sub-gasket 132 in the thickness direction. That is, the first window and the second window may be empty holes.

[0081] In other words, when the surface of the first sub-pad 131 facing the hydrogen-generating electrode 121 is referred to as the first surface and the surface opposite to the first surface is referred to as the second surface, the hydrogen-generating electrode 121 can penetrate the first and second surfaces of the first sub-pad 131, and the hydrogen-generating electrode 121 can be exposed on the second surface of the first sub-pad 131. Similarly, when the surface of the second sub-pad 132 facing the oxygen-generating electrode 122 is referred to as the first surface and the surface opposite to the first surface is referred to as the second surface, the oxygen-generating electrode 122 can penetrate the first and second surfaces of the second sub-pad 132, and the oxygen-generating electrode 122 can be exposed on the second surface of the second sub-pad 132. The first sub-pad 131 can surround the hydrogen-generating electrode 121, and the second sub-pad 132 can surround the oxygen-generating electrode 122.

[0082] The first sub-gasket 131 has a first water supply path P11 corresponding to the inactive region 110a of the polymer electrolyte membrane 110. In other words, the first water supply path P11 of the first sub-gasket 131 can overlap with the inactive region 110a of the polymer electrolyte membrane 110 in the thickness direction.

[0083] For example, in the plan view of the first sub-gasket 131, the first water supply path P11 may be located in the region corresponding to the inactive region 110a of the polymer electrolyte membrane 110. The first water supply path P11 may be positioned at a predetermined distance from the first window and may surround the first window. For example, the first water supply path P11 may extend to surround the four sides of the first window. However, one end and the other end of the first water supply path P11 may not intersect and may be spaced apart from each other. Therefore, the first sub-gasket 131 may have a single connection structure in which the first window portion and the first water supply path P11 portion are not separated.

[0084] The first water supply path P11 can be a hole penetrating the first sub-pad 131 in the thickness direction. That is, the first water supply path P11 can be an empty hole. Therefore, the inactive region 110a of the polymer electrolyte membrane 110 can be exposed to the second surface of the first sub-pad 131 through the first water supply path P11 of the first sub-pad 131.

[0085] During the operation of the water electrolysis cell or the activation process of the polymer electrolyte membrane 100, water is supplied to the first water supply path P11, which is a pore, so that water flows along the first water supply path P11.

[0086] When water reaches the inactive region 110a of the polymer electrolyte membrane 110 through the first water supply path P11 of the first sub-shield 131, a water concentration difference appears between the inactive region 110a and the active region of the polymer electrolyte membrane 110. As a result, according to Fick's law of diffusion, which states that water flows from a region of high concentration to a region of low concentration, water flows from the inactive region 110a to the active region. By directly supplying water to the polymer electrolyte membrane 110 to increase its water content, thereby increasing the ionic conductivity of the polymer electrolyte membrane 110, and by using additional cooling of the membrane electrode assembly to reduce the energy required, the performance of the water electrolysis cell can be maximized.

[0087] Meanwhile, the second sub-gasket 132 does not have a water supply path corresponding to the inactive region 110a of the polymer electrolyte membrane 110.

[0088] For example, in the plan view of the second sub-pad 132, the region corresponding to the inactive region 110a of the polymer electrolyte membrane 110 does not have a water supply path and is blocked by the second sub-pad 132. Therefore, the inactive region 110a of the polymer electrolyte membrane 110 is not exposed to the second surface of the second sub-pad 132.

[0089] Because the oxygen-generating electrode 122 is in contact with water, and the polymer electrolyte membrane 110 on one side of the oxygen-generating electrode 122 has a relatively high water content, no additional water supply is required. Furthermore, the catalyst layer of the oxygen-generating electrode 122 contains noble metal oxides such as iridium oxide, oxides of iridium alloys, or combinations thereof, and because these noble metal oxides are hydrophilic, they help to further increase the water content of the oxygen-generating electrode 122, thus eliminating the need for additional water supply to the oxygen-generating electrode 122.

[0090] For example, such as Figure 1 As shown, the first sub-pad 131 and the second sub-pad 132 may be of an overlapping type in which the edge portions of the hydrogen generation electrode 121 and the oxygen generation electrode 122 are covered by the first sub-pad 131 and the second sub-pad 132, but are not limited thereto, and the first sub-pad 131 and the second sub-pad 132 may be of an edge-embedded type in which the entire hydrogen generation electrode 121 and the entire oxygen generation electrode 122 are exposed through the first window and the second window, respectively.

[0091] The first sub-gasket 131 and the second sub-gasket 132 can be in the form of a membrane formed from a non-porous material, exhibiting good heat and chemical resistance in a temperature range from room temperature to 120°C, withstanding pressures greater than or equal to 100 Nm, and possessing relatively low gas permeability. For example, the first sub-gasket 131 and the second sub-gasket 132 may each comprise polyimide (PI), polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), fluorinated ethylene propylene (FEP), polyethylene naphthalate (PEN), or combinations thereof.

[0092] Figure 3 This is a cross-sectional view of a membrane electrode assembly according to one embodiment. Figure 4 It is based on Figure 3 A plan view of the membrane electrode assembly.

[0093] Reference Figure 3 and Figure 4 In addition to including a first gas diffusion layer 141 on the hydrogen production electrode 121 and a second gas diffusion layer 142 on the hydrogen production electrode 122, this membrane electrode assembly is... Figure 1 and Figure 2 The membrane electrode assembly shown is the same.

[0094] The first gas diffusion layer 141 and the second gas diffusion layer 142 can provide gas diffusion paths from the flow channels of the first separator 161 and the second separator 162 (described later) to the hydrogen-producing electrode 121 and the oxygen-producing electrode 122, so that the supply fluid can be easily and uniformly supplied to the hydrogen-producing electrode 121 and the oxygen-producing electrode 122, allowing the removal of products from the hydrogen-producing electrode 121 and the oxygen-producing electrode 122, preventing a rapid decrease in the water content of the polymer electrolyte membrane 110 by storing a certain amount of water, and providing sufficient mechanical strength to the membrane electrode assembly.

[0095] For example, the first gas diffusion layer 141 located on the side of the hydrogen production electrode 121 can be a gas diffusion layer (GDL) made of carbon material, and the second gas diffusion layer 142 located on the side of the oxygen production electrode 122 can be a porous transport layer (MPL) or a porous transport layer (PTL) made of metal material.

[0096] For example, the first gas diffusion layer 141 may include conductive porous components, such as carbon paper, carbon cloth, carbon felt, metal paper, metal cloth, metal felt, etc.

[0097] Furthermore, the second gas diffusion layer 142 may include multiple fibers. These fibers may be integrated in the form of a nonwoven fabric comprising multiple pores. The fibers may include metal oxides or metals. For example, the fibers may be metal oxides, including titanium dioxide (TiO2), tungsten oxide (WO3), silicon oxide (SiO2), ruthenium oxide (RuO2), ATO, ITO, manganese dioxide (MnO2), or molybdenum trioxide (MoO3), or metals, including titanium (Ti), gold (Au), or stainless steel (SUS). Therefore, when the second gas diffusion layer 142 includes multiple fibers containing metal oxides such as titanium (TiO2), the hydrophilic properties of the metal oxide can help further increase the water content of the oxygen-generating electrode 122, thus eliminating the need for additional water supply to the oxygen-generating electrode 122.

[0098] The diameter and length of the multiple fibers can be within a predetermined range. The diameter and length of the multiple fibers can be measured by imaging the second gas diffusion layer 142 using a scanning electron microscope (SEM). For example, the fiber diameter can be from 5 μm to 100 μm, and the fiber length can be from 10 μm to 2 mm.

[0099] The thickness and porosity of the second gas diffusion layer 142 can be appropriately adjusted to ensure adequate diffusion of the reactants. For example, the thickness of the second gas diffusion layer 142 can be within a predetermined range. The thickness of the second gas diffusion layer 142 can be measured by measuring the diameter and length of multiple fibers. The thickness of the second gas diffusion layer 142 can be from 30 μm to 500 μm. Furthermore, the porosity of the second gas diffusion layer 142 can be within a predetermined range. The porosity of the second gas diffusion layer 142 can be measured by mercury intrusion porosimetry. The porosity of the second gas diffusion layer 142 can be from 30% to 80%.

[0100] Figure 5 This is a cross-sectional view of a membrane electrode assembly according to one embodiment. Figure 6 It is based on Figure 5 A plan view of the membrane electrode assembly.

[0101] Reference Figure 5 and Figure 6 In addition to the membrane electrode assembly including a first gasket 151 disposed on the first sub-gasket 131 and surrounding the first gas diffusion layer 141, and a second gasket 152 disposed on the second sub-gasket 132 and surrounding the second gas diffusion layer 142, the membrane electrode assembly is... Figure 3 and Figure 4 The membrane electrode assembly shown is the same.

[0102] The first gasket 151 can be disposed on the first surface of the inactive region 110a of the polymer electrolyte membrane 110, and the second gasket 152 can be disposed on the second surface of the inactive region 110a of the polymer electrolyte membrane 110.

[0103] The first gasket 151 and the second gasket 152 each have a third window and a fourth window to accommodate the first gas diffusion layer 141 and the second gas diffusion layer 142, and to expose the first gas diffusion layer 141 and the second gas diffusion layer 142. For example, the third window may be a hole located in the central portion of the first gasket 151 and penetrating the first gasket 151 in the thickness direction. Similarly, the fourth window may be a hole located in the central portion of the second gasket 152 and penetrating the second gasket 152 in the thickness direction. That is, the third and fourth windows may be open holes.

[0104] In other words, when the surface of the first gasket 151 facing the hydrogen-producing electrode 121 is referred to as the first surface and the surface opposite to the first surface is referred to as the second surface, the first gas diffusion layer 141 can penetrate the first and second surfaces of the first gasket 151, and the first gas diffusion layer 141 can be exposed on the second surface of the first gasket 151. Similarly, when the surface of the second gasket 152 facing the oxygen-producing electrode 122 is referred to as the first surface and the surface opposite to the first surface is referred to as the second surface, the second gas diffusion layer 142 can penetrate the first and second surfaces of the second gasket 152, and the second gas diffusion layer 142 can be exposed on the second surface of the second gasket 152. The first gasket 151 can surround the first gas diffusion layer 141, and the second gasket 152 can surround the second gas diffusion layer 142.

[0105] The first gasket 151 has a third water supply path P21 corresponding to the inactive region 110a of the polymer electrolyte membrane 110. In other words, the third water supply path P21 of the first gasket 151 can overlap with the inactive region 110a of the polymer electrolyte membrane 110 in the thickness direction.

[0106] For example, in the plan view of the first gasket 151, the third water supply path P21 may be located in the region corresponding to the inactive region 110a of the polymer electrolyte membrane 110. Furthermore, the third water supply path P21 may be located in the region corresponding to the first water supply path P11 of the first sub-gasket 131. The third water supply path P21 may be positioned at a predetermined distance from the third window and may surround the third window. For example, the third water supply path P21 may extend to surround the four sides of the third window. However, one end and the other end of the third water supply path P21 may not intersect and may be spaced apart from each other. Therefore, the first gasket 151 may have a single construction in which the third window portion and the third water supply path P21 portion are connected without separation.

[0107] The third water supply path P21 can be a hole penetrating the first gasket 151 in the thickness direction. That is, the third water supply path P21 can be an empty hole. Therefore, the inactive region 110a of the polymer electrolyte membrane 110 can be exposed to the second surface of the first gasket 151 through the third water supply path P21 of the first gasket 151.

[0108] When water reaches the inactive region 110a of the polymer electrolyte membrane 110 through the third water supply path P21 of the first gasket 151, a water concentration difference appears between the inactive region 110a and the active region of the polymer electrolyte membrane 110. As a result, according to Fick's law of diffusion, which states that water flows from a region of high concentration to a region of low concentration, water flows from the inactive region 110a to the active region. By directly supplying water to the polymer electrolyte membrane 110 to increase its water content, the ionic conductivity of the polymer electrolyte membrane 110 is improved, and the required energy is reduced by additionally cooling the membrane electrode assembly, thus maximizing the performance of the water electrolysis cell.

[0109] Meanwhile, the second gasket 152 does not have a water supply path corresponding to the inactive region 110a of the polymer electrolyte membrane 110.

[0110] For example, in the plan view of the second gasket 152, the region corresponding to the inactive region 110a of the polymer electrolyte membrane 110 does not have a water supply path and is blocked by the second gasket 152. Therefore, the inactive region 110a of the polymer electrolyte membrane 110 is not exposed to the second surface of the second gasket 152.

[0111] The first gasket 151 and the second gasket 152 are used to prevent fluid leakage and may include, for example, ethylene propylene diene monomer (EPDM), chloroprene rubber, polyurethane, nitrile rubber (NBR), or polytetrafluoroethylene (PTFE).

[0112] Figure 7 It is a cross-sectional view of a water electrolysis cell according to one implementation plan. Figure 8 yes Figure 7 The plan view of the separator shown illustrates the surface facing the membrane electrode assembly.

[0113] Reference Figure 7 and Figure 8 The water electrolysis cell includes a membrane electrode assembly, a first separator 161 located on a first surface of the membrane electrode assembly, and a second separator 162 located on a second surface of the membrane electrode assembly.

[0114] As described above, the membrane electrode assembly includes: a polymer electrolyte membrane 110 having an active region and an inactive region 110a surrounding the active region; a hydrogen generation electrode 121 located on a first surface of the active region of the polymer electrolyte membrane 110; an oxygen generation electrode 122 located on a second surface of the active region of the polymer electrolyte membrane 110; a first gasket 151 disposed on the first surface of the inactive region 110a of the polymer electrolyte membrane 110 and surrounding the hydrogen generation electrode 121; and a second sub-gasket 132 disposed on the second surface of the inactive region 110a of the polymer electrolyte membrane 110 and surrounding the oxygen generation electrode 122. The first sub-gasket 131 may have a first water supply path P11 exposing the inactive region 110a of the polymer electrolyte membrane 110.

[0115] Furthermore, the membrane electrode assembly may further include a first gas diffusion layer 141 located on the hydrogen production electrode 121 and a second gas diffusion layer 142 located on the oxygen production electrode 122, and may further include a first gasket 151 disposed on a first sub-gasket 131 and surrounding the first gas diffusion layer 141, and a second gasket 152 disposed on a second sub-gasket 132 and surrounding the second gas diffusion layer 142. The first gasket 151 may have a third water supply path P21 corresponding to the inactive region 110a of the polymer electrolyte membrane 110.

[0116] The first partition 161 has a first flow channel 161a for supplying a first gas to the hydrogen production electrode 121, and the second partition 162 has a second flow channel 162a for supplying a second gas to the hydrogen production electrode 122. The gas inlet GI and the gas outlet GO can be located at one end of the first flow channel 161a and the other end of the second flow channel 162a, respectively.

[0117] The first separator 161 may have water channels 161b corresponding to the inactive region 110a of the polymer electrolyte membrane 110. In other words, the water channels 161b of the first separator 161 may overlap with the inactive region 110a of the polymer electrolyte membrane 110 in the thickness direction.

[0118] For example, in the plan view of the first separator 161, the water channel 161b may be located in the region corresponding to the inactive region 110a of the polymer electrolyte membrane 110. The water channel 161b may be positioned at a predetermined distance from the first flow channel 161a and may surround the first flow channel 161a. For example, the water channel 161b may extend to surround the four sides of the first flow channel 161a. However, one end and the other end of the water channel 161b may not intersect and may be spaced apart from each other. The inlet WI and the outlet WO may be located at one end and the other end of the water channel 161b, respectively. Therefore, the first separator 161 includes only a total of four minimized inlets and outlets, namely the gas inlet GI and gas outlet GO of the first flow channel 161a, and the inlet WI and outlet WO of the water channel 161b, thereby achieving a compact construction.

[0119] For example, the area ratio of the total area of ​​the water channel 161b to the total area of ​​the first separator 161 can be 10% to 80%, and the depth ratio of the total thickness of the first water channel 161b to the total thickness of the first separator 161 can be 5% to 40%. When the area ratio of the water channel 161b is less than 10% or the depth ratio of the first water channel 161b is less than 5%, water may not be adequately supplied to the inactive region 110a of the polymer electrolyte membrane 110 through the first water supply path P11 and the third water supply path P21. When the area ratio of the water channel 161b is greater than 80% or the depth ratio of the first water channel 161b is greater than 40%, excessive water may be supplied to the inactive region 110a of the polymer electrolyte membrane 110, leading to overflow, or the water concentration gradient may become smaller, making it impossible for water to be supplied to the active region according to Fick's diffusion law.

[0120] When water flows into the inlet WI of the first separator 161 and along the water channel 161b, the water is supplied to the inactive region 110a of the polymer electrolyte membrane 110 through the first water supply path P11 of the first sub-gasket 131, and the remaining water is discharged to the outlet WO of the first separator 161. When water reaches the inactive region 110a of the polymer electrolyte membrane 110 through the first water supply path P11 of the first sub-gasket 131, a water concentration difference appears between the inactive region 110a and the active region of the polymer electrolyte membrane 110. As a result, according to Fick's law of diffusion, which states that water flows from a high concentration to a low concentration, water flows from the inactive region 110a to the active region. By directly supplying water to the polymer electrolyte membrane 110 to increase the water content of the polymer electrolyte membrane 110, thereby increasing the ionic conductivity of the polymer electrolyte membrane 110, and by using additional cooling of the membrane electrode assembly to reduce the required energy, the performance of the water electrolysis cell can be maximized.

[0121] Preparation example: Preparation of membrane electrode assembly

[0122] Commercially available IrO2 will be used as a catalyst for the oxygen production reaction. x Black powder (Merck Sigma-Aldrich, iridium oxide (IV) 206237) and Nafion, as an ionic conductor, were mixed in n-propanol (nPA) as a solvent, such that their weight ratio was 1:0.2 (IrO). x ∶Nafion). Further mixing with solvents resulted in a solids content of 5% by weight. The mixture was then sprayed onto a coating substrate (PI Advanced Materials, PI film) with a width of 2 cm, a length of 2 cm, and a thickness of approximately 200 μm, resulting in a loading of 0.5 mg / cm². 2 To form an oxygen-generating electrode with a thickness of approximately 10 μm.

[0123] Pt / C carbon with a Pt loading of 50 wt% was mixed with Nafion, an ionic conductor, at a weight ratio of 1:1.2 (Pt / C:Nafion), and further mixed with solvent to achieve a solid content of 5 wt%. The mixture was then sprayed onto a coating substrate (PI Advanced Materials, PI film) with a width of 2 cm, a length of 2 cm, and a thickness of approximately 200 μm, resulting in a loading of 0.5 mg / cm³. 2 To form a hydrogen production electrode with a thickness of approximately 30 μm.

[0124] The oxygen-generating electrode and the hydrogen-generating electrode were sequentially overlapped on two surfaces of a commercially available NR212 material with a thickness of approximately 50.8 μm manufactured by Chemours, which served as a polymer electrolyte membrane. The membrane was then hot-pressed at 150 °C and 5 N for 5 minutes, and the coated base film was removed to prepare the polymer electrolyte membrane electrode assembly.

[0125] like Figure 7 and Figure 8 As shown, a first sub-pad 131 having a first water supply path P11 and a second sub-pad 132 without a water supply path are laminated onto the two surfaces of the prepared polymer electrolyte membrane electrode assembly. Then, a first gas diffusion layer 141 of carbon material and a second gas diffusion layer 142 of metal material, a first pad 151 having a third water supply path P21 and a second sub-pad 132 without a water supply path, and a first separator 161 having a water channel 161b and a second separator 162 without a water channel are stacked in sequence to prepare a water electrolysis cell according to the embodiment.

[0126] In addition, except for using a first sub-gasket 131 that does not have a first water supply path P11, a first gasket 151 that does not have a third water supply path P21, and a first separator 161 that does not have a water channel 161b, the water electrolysis cell according to the comparative example is prepared in the same manner as in the embodiment.

[0127] Experimental Example: Measurement of Water Content in Polymer Electrolyte Membranes

[0128] The water content of the polymer electrolyte membrane in the water electrolysis cells according to the examples and comparative examples was measured, and the results are shown in Table 1.

[0129] Water content was measured using an X-ray microtomography device via a λ measurement method.

[0130] (1) Configuration of experimental setup

[0131] 1) X-ray micro-computed tomography device: Advanced Light Source (ALS) based synchrotron X-ray micro-computed tomography system.

[0132] - X-ray source: Compared with conventional laboratory equipment, the use of synchrotron X-ray sources provides very high photon flux and high spatial resolution.

[0133] - Spatial resolution: It has a high resolution of about 1μm and can accurately visualize the water distribution and density changes of each pixel.

[0134] - Temporal resolution: Each imaging session is set to a temporal resolution of approximately 10 minutes, thus allowing for the tracking of dynamic changes in material movement over time.

[0135] 2) Sample fixation device and support: A specially designed sample support is used to fix the polymer electrolyte membrane sample.

[0136] - Sample holding device structure: designed to precisely hold the polymer electrolyte membrane sample in place and generate various water boundaries.

[0137] - Gas flow control: Dry nitrogen (N2) is supplied to one surface of the polymer electrolyte membrane sample, while vapor or liquid containing moisture is supplied to the other surface, thereby setting various boundary conditions. This creates an environment where one surface of the polymer electrolyte membrane is dry while the other surface is in contact with vapor or liquid.

[0138] - Temperature and humidity control function: It can precisely control the temperature and humidity inside the sample holder, so that a constant environment can be maintained during the experiment.

[0139] - Water supply function to the gasket channel: Designed to supply water to the gasket channel and control the flow rate, and used in conjunction with a precision pump.

[0140] (2) Experimental steps

[0141] 1) Initial Sample Preparation: Polymer electrolyte membrane samples in a dry state, a vapor-saturated state, and a liquid-saturated state were prepared and tested. The initial state settings of the samples are as follows.

[0142] -Dry state: Water content λ=2.

[0143] -Steam saturation state: water content λ=14.

[0144] - Liquid saturation state: water content λ=22.

[0145] 2) Experimental details: Set various boundary conditions to clearly observe the water distribution and moisture movement in the polymer electrolyte membrane.

[0146] Water was supplied at a rate of -5 cc / min to the gasket of the hydrogen-producing electrode and at a rate of 10 cc / min to the gasket of the oxygen-producing electrode, in the same manner as in actual water electrolysis.

[0147] -Contour variation over time: Images of water distribution at each time interval were captured using X-ray microtomography. It was confirmed that initially, the λ value started from 2, gradually increased over time, and stabilized at a specific λ value.

[0148] [Table 1]

[0149] Referring to Table 1, in the case of the water electrolysis cell according to the embodiment, since water is supplied to the hydrogen production electrode side only through the water channel instead of the first flow channel, and water is supplied to the oxygen production electrode side through the second flow channel, water flows from the inactive region 110a to the active region according to Fick's diffusion law, thereby directly supplying water to the polymer electrolyte membrane 110. Therefore, it can be seen that the water content of the polymer electrolyte membrane 110 increases.

[0150] On the other hand, in the case of the water electrolyzer according to the comparative example, water is not supplied to the hydrogen production electrode side at all, but is supplied to the oxygen production electrode side through the second flow channel. Therefore, it can be seen that in the water electrolyzer according to the comparative example, the polymer electrolyte membrane has a lower water content compared to the water electrolyzer according to the embodiment.

[0151] Although preferred embodiments of the present disclosure have been described above, the present disclosure is not limited thereto, and various modifications and implementations can be made within the scope of the claims, description and drawings, and these naturally fall within the scope of the present disclosure.

[0152] Explanation of reference numerals in the attached figures

[0153] 110: Polymer electrolyte membrane

[0154] 110a: Inactive region

[0155] 121: Hydrogen production electrode

[0156] 122: Oxygen-generating electrode

[0157] 131: First sub-wafer

[0158] 132: Second sub-wafer

[0159] P11: First water supply route

[0160] 141: First gas diffusion layer

[0161] 142: Second gas diffusion layer

[0162] 151: First gasket

[0163] 152: Second gasket

[0164] P21: Third water supply route

[0165] 161: First dividing piece

[0166] 161a: First flow channel

[0167] 162: Second separator

[0168] 162a: Second flow channel

[0169] 161b: Waterway

[0170] Industrial applicability

[0171] This disclosure relates to a membrane electrode assembly for a water electrolyzer and a water electrolyzer including the membrane electrode assembly, and the performance of the water electrolyzer can be maximized by increasing the water content of the polymer electrolyte membrane by directly supplying water to the polymer electrolyte membrane, thereby increasing the ionic conductivity of the polymer electrolyte membrane, and by additionally cooling the membrane electrode assembly to reduce the energy required.

Claims

1. A membrane electrode assembly for a water electrolysis cell, comprising: A polymer electrolyte membrane having an active region and an inactive region surrounding the active region; A hydrogen-generating electrode, wherein the hydrogen-generating electrode is located on the first surface of the active region of the polymer electrolyte membrane; An oxygen-generating electrode is located on the second surface of the active region of the polymer electrolyte membrane; A first sub-pad is disposed on a first surface of the inactive region of the polymer electrolyte membrane and surrounds the hydrogen-generating electrode; as well as The second sub-pad is disposed on the second surface of the inactive region of the polymer electrolyte membrane and surrounds the oxygen-generating electrode. The first sub-pad has a first window for accommodating the hydrogen-generating electrode and a first water supply path surrounding the first window and exposing an inactive region of the polymer electrolyte membrane.

2. The membrane electrode assembly for a water electrolysis cell according to claim 1, wherein, The first window penetrates the first sub-pad to expose the hydrogen-producing electrode, and the first water supply path penetrates the first sub-pad to expose the inactive region of the polymer electrolyte membrane.

3. The membrane electrode assembly for a water electrolysis cell according to claim 1, wherein, The first window and the first water supply path are hollow.

4. The membrane electrode assembly for a water electrolysis cell according to claim 1, wherein, The first water supply path extends around the four sides of the first window, and one end of the first water supply path does not intersect with the other end and is spaced apart from each other.

5. The membrane electrode assembly for a water electrolysis cell according to claim 1, wherein, The second sub-pad has a second window that accommodates the oxygen-generating electrode and does not have a water supply path that exposes the inactive area of ​​the polymer electrolyte membrane.

6. The membrane electrode assembly for a water electrolysis cell according to claim 5, wherein, The oxygen-generating electrode includes a noble metal oxide catalyst, which includes iridium oxide, oxides of iridium alloys, or combinations thereof.

7. The membrane electrode assembly for a water electrolysis cell according to claim 1, wherein, The membrane electrode assembly for the water electrolysis cell further includes: A first gas diffusion layer located on the hydrogen-producing electrode; and a second gas diffusion layer located on the oxygen-producing electrode.

8. The membrane electrode assembly for a water electrolysis cell according to claim 7, wherein, The first gas diffusion layer includes a conductive porous component, which includes carbon paper, carbon cloth, carbon felt, metal paper, metal cloth, metal felt, or a combination thereof.

9. The membrane electrode assembly for a water electrolysis cell according to claim 7, wherein, The second gas diffusion layer comprises multiple fibers integrated in the form of multiple pores, and the multiple fibers comprise metal oxides or metals.

10. The membrane electrode assembly for a water electrolysis cell according to claim 7, wherein, The membrane electrode assembly for the water electrolysis cell further includes: A first gasket, disposed on the first sub-gasket and surrounding the first gas diffusion layer; and a second gasket, disposed on the second sub-gasket and surrounding the second gas diffusion layer. The first gasket has a third window for accommodating the first gas diffusion layer and a third water supply path surrounding the third window and exposing the first water supply path of the first gas diffusion layer.

11. A water electrolysis cell, comprising: The membrane electrode assembly according to claim 1; A first separator located on a first surface of the membrane electrode assembly; and a second separator located on the second surface of the membrane electrode assembly, The first separator has a flow channel located in the region corresponding to the hydrogen production electrode, and a water channel surrounding the first flow channel and located in the region corresponding to the first water supply path.

12. The water electrolysis cell according to claim 11, wherein, The water channels extend around the four sides of the flow channel, and one end of the water channels does not intersect with the other end and is spaced apart from each other.

13. The water electrolysis cell according to claim 11, wherein, The water channel has an inlet at one end and an outlet at the other end.

14. The water electrolysis cell according to claim 11, wherein, The area ratio of the water channel to the total area of ​​the first partition is 10% to 80%, and the depth ratio of the water channel to the total thickness of the first partition is 5% to 40%.

15. The water electrolysis cell according to claim 11, wherein, The water electrolysis cell further includes: A first gas diffusion layer located on the hydrogen-producing electrode; and a second gas diffusion layer located on the oxygen-producing electrode. The second gas diffusion layer comprises multiple fibers integrated in the form of multiple pores, and the multiple fibers comprise metal oxides or metals.

16. The water electrolysis cell according to claim 15, wherein, The water electrolysis cell further includes: A first gasket, disposed on the first sub-gasket and surrounding the first gas diffusion layer; and a second gasket, disposed on the second sub-gasket and surrounding the second gas diffusion layer. The first gasket has a third window for accommodating the first gas diffusion layer and a third water supply path surrounding the third window and exposing the first water supply path of the first gas diffusion layer.

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