WATER ELECTROLYSIS STACK HAVING EFFICIENT FLUID DISTRIBUTION STRUCTURE

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2024-0166668, filed on Nov. 20, 2024, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to a water electrolysis stack having an efficient fluid distribution structure.

2. Discussion of Related Art

Electrolysis refers to a technology of producing hydrogen by electrolyzing pure water, can respond to the currently increasing demand for hydrogen, and can also be used as a large-capacity power storage technology that stores renewable energy such as wind power and solar energy. Hydrogen has advantages in that it can have high energy density, can be stored stably for a long time, and can be stored in various forms such as gas or liquid.

The basic concept of a water electrolysis stack has the same as the production of hydrogen and oxygen through an electrolysis reaction but is classified as alkaline water electrolysis (AWE), proton exchange membrane water electrolysis (PEMWE), anion exchange membrane water electrolysis (AEMWE), and solid oxide electrolysis cell (SOEC) according to an electrolyte that is used. In particular, AEMWE uses an anion exchange membrane as an electrolyte and can reduce the cost of hydrogen production by using low-cost catalysts such as AWE. Since this technology can operate effectively even at low power and operate at a high pressure without a compressor, there is high efficiency and purity.

Various manifolds for supplying or discharging hydrogen, air, and cooling water are formed on upper and lower portions of the water electrolysis stack.

Since a conventional water electrolysis stack is formed of an end plate with a single through-type manifold and a cell frame with a flow path broadly branched from both ends of one manifold, a relatively large amount of fluid flows in a central portion of an active area, but due to a small flow rate of the fluid, a relatively small amount of fluid flows at both ends (edges) of the active area.

The conventional water electrolysis stack has a disadvantage in that the entire active area cannot be used as an electrochemical reaction region, which can lead to degradation of the performance of a stack and a decrease in durability and also lead to an increase in material costs due to waste of a membrane, a catalyst, etc. In addition, when 100% of the active area cannot be used as the reaction area, it can act as a factor which increases the number of cells in the stack and a risk occurring between fastening and movement of the stack, and the like in addition to the increase in cost due to the increase in the number of cells, which can also be problematic.

SUMMARY OF THE INVENTION

The present invention is directed to providing a water electrolysis stack having a fluid distribution structure in which a constant and uniform fluid may flow in all regions of an active area.

The present invention is also directed to providing a water electrolysis stack capable of ultimately improving performance of a stack and reducing cost uniformly by using an active area of a water electrolysis stack as an electrochemical reaction region.

According to an aspect of the present invention, there is provided a water electrolysis stack including one or more stacks in which a cathode cell frame, a membrane electrode assembly, and an anode cell frame are sequentially stacked, and a pair of end plates which fasten the one or more stacks from both sides in a stacking direction, wherein one side of the end plate is provided with a plurality of first inflow holes formed in parallel to be spaced a predetermined distance from each other, the other side of the end plate is provided with a plurality of first discharge holes formed in parallel to be spaced a predetermined distance from each other, one side of each of the cathode cell frame and the anode cell frame is provided with a plurality of second inflow holes formed in parallel to be spaced a predetermined distance from each other, the other side of each of the cathode cell frame and the anode cell frame is provided with a plurality of second discharge holes formed in parallel to be spaced a predetermined distance from each other, the first inflow hole and the second inflow hole are stacked to form an inlet manifold for an electrolyte, the first discharge hole and the second discharge hole are stacked to form an outlet manifold for an electrolyte, a first expansion expanding from the first inflow hole in a spacing direction of the first inflow hole and a second expansion expanding from the first discharge hole in a spacing direction of the first discharge hole are formed on a surface of the end plate, which is adjacent to the stack, the first inflow hole communicates with at least two second inflow holes through the first expansion, and the first discharge hole communicates with at least two second discharge holes through the second expansion.

The first inflow hole may communicate with two to four second inflow holes, and the first discharge hole may communicate with two to four second discharge holes.

A fluid diffusion layer may be provided on a central portion of each of the cathode cell frame and the anode cell frame, at least one of the cathode cell frame and the anode cell frame may be provided with a plurality of first protrusions, which allow the second inflow hole to communicate with the fluid diffusion layer and are formed in parallel to be spaced a predetermined distance from each other in a direction perpendicular to a flowing direction of an electrolyte, and a plurality of second protrusions allow the second discharge hole to communicate with the fluid diffusion layer and are formed in parallel to be spaced a predetermined distance from each other in the direction perpendicular to the flowing direction of the electrolyte.

The first and second protrusions may be formed of multiple levels in the flowing direction of the electrolyte.

The first and second protrusions may have corners each having a rounded cross-sectional shape.

The fluid diffusion layer may include a plurality of pores and has a porosity of 65 to 85 volume %.

A flow path may be formed on at least one surface of the fluid diffusion layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The above matters and other objects, features, and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing exemplary embodiments thereof in detail by referencing the accompanying drawings, in which:

FIG. 1 is a schematic exploded perspective view for describing a water electrolysis stack according to one embodiment of the present invention;

FIG. 2 is a schematic perspective view for describing a first expansion of an end plate;

FIG. 3 is a schematic perspective view for describing a second protrusion of an anode cell frame; and

FIG. 4 is a schematic cross-sectional view for describing a fluid diffusion layer in which a flow path is formed on at least one surface.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Advantages and features of the present invention and methods for achieving them will become clear by referencing embodiments described below in detail together with the accompanying drawings.

However, the present invention is not limited to the embodiments disclosed below but can be implemented in various different forms, these embodiments are merely provided to make the disclosure of the present invention complete and fully inform those skilled in the art to which the present invention pertains of the scope of the present invention, and the present invention is only defined by the scope of the appended claims. The same reference numerals denote the same components throughout the specification.

Accordingly, in some embodiments, well-known process operations, well-known structures, and well-known technologies are not specifically described to avoid ambiguous construction of the present invention.

Terms used in the present specification are intended to describe the embodiments and are not intended to limit the present invention. In the present specification, the singular form also includes the plural form unless specifically stated in a phrase.

Throughout the present specification, when a predetermined portion is described as being “connected to” another portion, it includes not only a case in which the predetermined portion is “directly connected” to another portion, but also a case in which the predetermined portion is “electrically connected” to another portion with still another portion interposed therebetween. In addition, throughout the present specification, when a predetermined portion is described as “including” a predetermined element, it means that the predetermined portion may further include another element rather than precluding another element unless specifically stated to the contrary.

A water electrolysis stack of the present invention is characterized by having at least two fluid distribution regions and fluid diffusion layers so that a fluid is sequentially and uniformly distributed and the fluid is uniformly distributed on all surfaces of an active area.

More specifically, openings (a first inflow hole and a first discharge hole) and expansions (a first expansion and a second expansion) provided in an end plate, which is one component of the water electrolysis stack, serve as a primary fluid distribution structure, and openings (a second inflow hole and a second discharge hole) included in a cell frame, which is another component of the water electrolysis stack, serve as a secondary fluid distribution structure. In addition, when protrusions (a first protrusion and a second protrusion) are formed between the openings (the second inflow hole and the second discharge hole) of the cell frame and reaction surfaces, the corresponding protrusions serve as a tertiary fluid distribution structure. In this case, the fluid flowing into the water electrolysis stack may sequentially move primary, secondary, and tertiary fluid distribution regions, and ultimately, the fluid may be uniformly distributed to the fluid diffusion layer of the active area. In the water electrolysis stack of the present invention having such a structure, a pressure difference of a fluid at an inlet and an outlet can be reduced, and the fluid can be uniformly distributed and discharged to the entire area of the fluid diffusion layer, thereby significantly improving performance of the water electrolysis stack and reducing cost. In addition, when the fluid diffusion layer is formed of a metal porous material having uniform porosity or a flow path is formed on at least one surface of the fluid diffusion layer, it can be more advantageous in terms of uniform and constant distribution of the fluid.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this case, it should be noted that the same component in the accompanying drawings is denoted with the same reference numeral as often as possible. Detailed descriptions of well-known functions and components which can obscure the gist of the present invention are omitted. For the same reason, some components in the accompanying drawings are exaggerated, omitted, or schematically illustrated, and the size of each component does not entirely reflect the actual size.

FIG. 1 is a schematic exploded perspective view for describing a water electrolysis stack according to one embodiment of the present invention, FIG. 2 is a schematic perspective view for describing a first expansion of an end plate, and FIG. 3 is a schematic perspective view for describing a second protrusion of an anode cell frame.

The water electrolysis stack according to one embodiment of the present invention includes one or more stacks in which a cathode cell frame 20, a membrane electrode assembly 30, and an anode cell frame 40 are sequentially stacked and a pair of end plates 10 which fasten the one or more stacks from both sides in a stacking direction.

The membrane electrode assembly 30 may include a membrane, a cathode electrode formed in close contact with one side of the membrane, and an anode electrode formed in close contact with the other side of the membrane.

The membrane may be an anion exchange membrane (AEM) but is not limited thereto.

In the cathode electrode, as shown in Reaction Formula 1 below, electrons supplied from an external power source react with water (H₂O) to generate hydrogen gas and OH⁻, and the OH⁻may move to the anode electrode through the membrane to generate water (H₂O) and oxygen gas as shown in Reaction Formula 2 below.

One side of the end plate 10 is provided with a plurality of first inflow holes 101 formed in parallel to be spaced a predetermined distance from each other, the other side of the end plate 10 is provided with a plurality of first discharge holes 103 formed in parallel to be spaced a predetermined distance from each other, one side of each of the cathode cell frame 20 and the anode cell frame 40 is provided with a plurality of second inflow holes 201 formed in parallel to be spaced a predetermined distance from each other, the other side of each of the cathode cell frame 20 and the anode cell frame 40 is provided with a plurality of second discharge holes 202 formed in parallel to be spaced a predetermined distance from each other, the first inflow hole 101 and the second inflow hole 201 are stacked to form an inlet manifold for an electrolyte, and the first discharge hole 103 and the second discharge hole 202 are stacked to form an outlet manifold for an electrolyte.

The plurality of first inflow holes 101 and the plurality of first discharge holes 103 may all have the same area and shape, and the shape may be rectangular, square, circular, semicircular, irregular, or the like, but is not limited thereto.

The plurality of second inflow holes 201 and the plurality of second discharge holes 202 may all have the same area and shape, and the shape may be rectangular, square, circular, semicircular, irregular, or the like, but is not limited thereto.

A first expansion 102 expanding from the first inflow hole 101 in a spacing direction of the first inflow hole 101 and a second expansion 104 expanding from the first discharge hole 103 in a spacing direction of the first discharge hole 103 are formed on a surface of the end plate 10, which is adjacent to the stack, the first inflow hole 101 communicates with at least two second inflow holes 201 through the first expansion 102, and the first discharge hole 103 communicates with at least two second discharge holes 202 through the second expansion 104.

That is, the first expansion 102 or the second expansion 104 with a size and area sufficient for covering two or more (e.g., 2 to 4) second inflow holes 201 or second discharge holes 202 positioned in a lower portion of the end plate 10 may be formed in a lower surface (a surface adjacent to the stack) of the end plate 10, and thus a fluid supplied from an inlet port of the water electrolysis stack or a fluid discharged from an outlet port of the water electrolysis stack may be uniformly distributed primarily.

FIGS. 1 and 2 illustrate sidewalls of the first inflow hole 101 or the first discharge hole 103 and the first expansion 102 or the second expansion 104, which are parallel to the stacking direction of the stack and are stepped, but the present invention is not necessarily limited thereto, and one or more of the first inflow hole 101 or the first discharge hole 103 and the first expansion 102 or the second expansion 104 may have a tapered shape in which the size of the hole increases toward the lower surface of the end plate 10. In some cases, the first inflow hole 101 or the first discharge hole 103 and the first expansion 102 or the second expansion 104 may be formed integrally.

The number of second inflow holes 201 and the number of second discharge holes 202 may be at least twice the number of first inflow holes 101 and the number of first discharge holes 103, and thus the fluid supplied from the inlet port of the water electrolysis stack or the fluid discharged from the outlet port of the water electrolysis stack may be uniformly distributed secondarily.

A central portion of the cathode cell frame 20 may be provided with a cathode-side fluid diffusion layer 301 as a reaction surface, and a central portion of the anode cell frame 40 may be provided with an anode-side fluid diffusion layer 302 as a reaction surface. Each of the cathode-side fluid diffusion layer 301 and the anode-side fluid diffusion layer 302 may include a plurality of pores and may be, for example, formed of a metal porous material having a porosity of 65 to 85 volume%. In this case, it can be more advantageous for uniform distribution or discharge of the fluid.

At least one of the cathode cell frame 20 and the anode cell frame 40 may be provided with a plurality of first protrusions 203, which allow the second inflow hole 201 to communicate with the fluid diffusion layers 301 and 302 and are formed in parallel to be spaced a predetermined distance from each other in a direction perpendicular to the flowing direction of the electrolyte, and a plurality of second protrusions 204 which allow the second discharge hole 202 to communicate with the fluid diffusion layers 301 and 302,and are formed in parallel to be spaced a predetermined distance from each other in a direction perpendicular to the flowing direction of the electrolyte.

The first and second protrusions 203 and 204 serve as connection passages connecting the manifold to the fluid diffusion layer. The number of first and second protrusions 203 and 204 (the number of protrusions arranged in a single row in the direction perpendicular to the flow direction of the electrolyte) may be at least twice the number of second inflow holes 201 and the number of second discharge holes 202, and thus the fluid supplied from the inlet port of the water electrolysis stack or the fluid discharged from the outlet port of the water electrolysis stack may be uniformly distributed in a three-dimensional manner.

The first and second protrusions 203 and 204 may all have the same area and cross-sectional shape, and the cross-sectional shape may be rectangular, square, trapezoid, octagon, circular, or the like, but is not limited thereto. Each of corners of the first and second protrusions 203 and 204 may have a rounded cross-sectional shape, and in this case, it can be more advantageous for smooth movement of the fluid, but the present invention is not limited thereto.

The first and second protrusions 203 and 204 may be formed of multiple levels in the flowing direction of the electrolyte, and the first and second protrusions 203 and 204 disposed in different stages may be disposed in a zigzag pattern. In this case, it can be more advantageous for uniform distribution of the fluid. In FIGS. 1 to 3, the first and second protrusions 203 and 204 are each formed in two stages, but are not limited thereto.

FIG. 4 is a schematic cross-sectional view for describing a fluid diffusion layer in which a flow path is formed on at least one surface.

As illustrated in FIG. 4, a flow path may be formed on at least one surface of the fluid diffusion layer, and in this case, it can be more advantageous for uniform distribution and discharge of the fluid.

The shape of the flow path may be a straight shape, a serpentine shape, a symmetrical shape, or the like, but is not limited thereto.

A water electrolysis stack of the present invention has a structure in which a fluid can be uniformly distributed to a fluid diffusion layer of an active area. Accordingly, according to the present invention, a pressure difference of a fluid at an inlet and an outlet can be reduced, and the fluid can be uniformly distributed and discharged to the entire area of the fluid diffusion layer, thereby significantly improving performance of the water electrolysis stack and reducing cost.

It should be understood that the effects of an aspect of the present invention are not limited to the above effects and include all effects inferable from the configuration described in the detailed description or claims of the invention of the present specification.

Although exemplary embodiments of the present invention have been described above, the scope of the present invention is not limited to only these specific embodiments, and those skilled in the art who understand the spirit of the present invention can easily propose other embodiments by adding, changing, and omitting a component within the obvious scope, but they should be construed as also belonging to the scope of the claims of the present invention.

The scope of the present specification is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and equivalent concepts thereof should be construed as being included in the scope of the present specification.

REFERENCE NUMERAL

• • 10: end plate 20: cathode cell frame
  • 30: membrane electrode assembly 40: anode cell frame
  • 101: first inflow holes 102: first expansion
  • 103: first discharge holes 104: second expansion
  • 201: second inflow holes 202: second discharge holes
  • 203: first protrusions 204: second protrusions
  • 301: cathode-side fluid diffusion layer 302: anode-side fluid diffusion layer