Separator, and water electrolysis cell and water electrolysis stack comprising same

Abstract

The present invention relates to a separator comprising: a metal plate including titanium; and a titanium mesh bonded to one surface of the metal plate, wherein the titanium mesh has a woven pattern and includes a specific ratio of a void area and a contact area, and thus can reduce contact resistance and facilitate material transfer.

Description

A separator, an electrolysis cell including the same, and an electrolysis stack

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0081312, filed June 21, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Technology field

[0005] The present invention relates to a separator, an electrolysis cell including the same, and an electrolysis stack.

[0006]

[0007] Hydrogen has the advantages of being easy to store and transport and being environmentally friendly, leading to various recent attempts to utilize it as an energy source. While various methods for producing hydrogen are known, producing hydrogen through water electrolysis has the advantage of being environmentally friendly, as it produces no harmful byproducts.

[0008] Representative methods of water electrolysis include alkaline electrolysis (AEC) and polymer electrolyte membrane electrolysis (PEM). Alkaline electrolysis uses an alkaline electrolyte to electrolyze water and is the most commercially available technology. Alkaline electrolysis boasts relatively low operating costs, a simple production structure, making it suitable for large-scale hydrogen production, and excellent durability. However, alkaline electrolysis requires continuous replenishment of the electrolyte consumed during the electrolysis process, and has limitations such as corrosion problems due to alkaline components and low current density efficiency. Meanwhile, polymer electrolyte membrane electrolysis utilizes a polymer electrolyte membrane as the electrolyte, primarily a cation exchange membrane. The principle of polymer electrolyte membrane electrolysis is that water (H2O) is supplied to the anode, where it decomposes into oxygen gas, electrons, and hydrogen ions. The hydrogen ions then pass through the polymer electrolyte membrane and are released as hydrogen gas. In electrolysis, precious metal catalysts are used, so operation is possible at high current densities, resulting in high energy efficiency. Furthermore, since no electrolyte components are required, the purity of the hydrogen produced is very high.

[0009] Meanwhile, water electrolysis devices are manufactured by stacking unit cells, which requires a bipolar plate with a bipolar surface positioned between multiple membrane electrode assemblies. Conventional bipolar plates have different flow path shapes on each bipolar surface depending on the purpose, making the manufacturing process complex and challenging to select materials that satisfy this processability. Furthermore, the surface of the bipolar plate facing the anode is made of titanium due to the corrosive environment. However, titanium requires high cutting strength due to its high strength, and the high frictional heat generated makes machining difficult, increasing processing costs. Therefore, to lower stack costs, the use of titanium that does not require machining is necessary. Furthermore, a thinner bipolar plate is desirable to reduce the cost of expensive Ti materials and reduce the weight of the stack. However, water electrolysis devices or systems require the cathode to operate under a pressurized environment of approximately 30 bar to produce compressed hydrogen. To prevent deformation of the bipolar plate and its materials, a certain thickness is inevitably required. In addition, in the past, mesh was laminated on one side of the separator to replace the flow path of the separator and used as a flow path. In this case, a mesh in the form of a lath or expanded metal was used to increase the contact area with the separator and other components of the cell. However, in the case of the mesh in the above form, there was not enough space or flow path for the fluid to pass or transport, resulting in a loss of material transport and a problem of deterioration of cell performance.

[0010] (Patent Document 1) KR 10-2023-0103585 A

[0011]

[0012] The problem to be solved by the present invention is to provide a separator having an excellent level of electrolytic performance by including a member that replaces a flow path without a separate processing operation for forming a flow path in the separator and by controlling and specifying the structure of the member.

[0013]

[0014] The present invention provides a separator, an electrolysis cell including the same, and an electrolysis stack.

[0015] (1) The present invention provides a separator comprising a metal plate including titanium; and a titanium mesh bonded to one surface of the metal plate, wherein the titanium mesh has a woven pattern, and the titanium mesh satisfies the following conditions 1 and 2.

[0016] [Condition 1]

[0017] The ratio of the empty space area on the side to the side area of ​​the unit mesh is 20% or more,

[0018] The lateral area of ​​the above unit mesh is calculated as (diameter + cross-section) × mesh thickness.

[0019] The above empty space area is an area formed by two wires having a rough shape through the above weaving pattern.

[0020] [Condition 2]

[0021] The ratio of the contact area to the area of ​​the unit mesh is 30% or more,

[0022] The above contact area refers to the area where the wire of the mesh comes into contact with the metal plate.

[0023] (2) The present invention provides a separator in the above (1) wherein the thickness of the titanium mesh is 200 ㎛ or more and 800 ㎛ or less.

[0024] (3) The present invention provides a separator in (1) or (2) above, wherein the mesh number of the titanium mesh is 10 mesh or more and 120 mesh or less.

[0025] (4) The present invention provides a separator according to any one of the above (1) to (3), wherein the metal plate further includes stainless steel, and the metal plate is a clad metal plate including titanium and stainless steel.

[0026] (5) The present invention provides a separator according to (4), wherein the clad metal plate includes a first layer containing titanium and a second layer containing stainless steel, and the thickness ratio of the first layer and the second layer is 10:90 to 30:70.

[0027] (6) The present invention provides a separator according to any one of the above (1) to (5), wherein the metal plate further includes an engineering plastic.

[0028] (7) The present invention provides a separator according to (6), wherein the engineering plastic includes at least one material selected from the group consisting of polyphenylene sulfide, polyphenylene sulfone, polysulfone, and polyether ether ketone.

[0029] (8) The present invention provides a separator in which the titanium mesh does not include a structure formed in the form of a lath or expanded metal in any one of the above (1) to (7).

[0030] (9) The present invention provides a separator in any one of the above (1) to (8), wherein the thickness of the metal plate is 0.1 mm or more and 5 mm or less.

[0031] (10) The present invention provides a separator according to any one of the above (1) to (9), wherein the separator does not include a euro.

[0032] (11) The present invention provides a water electrolysis cell including a first separator and a second separator according to any one of (1) to (10) above, and a membrane electrode assembly including an anode, a separator, and a cathode disposed between the first separator and the second separator.

[0033] (12) The present invention provides a water electrolysis cell including a gas diffusion layer disposed between the cathode and the first separator, and a porous diffusion layer disposed between the anode and the second separator, in the above (11).

[0034] (13) The present invention provides a water electrolysis cell according to (12), wherein the thickness of the gas diffusion layer is 150 ㎛ or more and 400 ㎛ or less, and the thickness of the porous diffusion layer is 200 ㎛ or more and less than 450 ㎛.

[0035] (14) The present invention provides a water electrolysis stack including a plurality of water electrolysis cells according to any one of the above (11) to (13).

[0036]

[0037] The separator of the present invention has a structure in which a separate flow path is not formed and a flow path is replaced with a titanium mesh, thereby reducing the process and cost required for flow path processing.

[0038] In addition, by specifying and controlling the structure of the titanium mesh and bonding the titanium mesh to a metal plate, the contact resistance can be lowered and material transfer can be improved to proceed smoothly, thereby achieving an excellent level of electrolysis cell performance.

[0039]

[0040] Fig. 1 is a cross-sectional view showing the separator structure of the present invention.

[0041] Figure 2 shows the mesh structure (a) of the present invention.

[0042] Figure 3 shows a unit mesh (b) of the present invention.

[0043] Figure 4 shows a side view (c) of the unit mesh of the present invention.

[0044] Figure 5 is a photograph showing the titanium mesh of Example 1.

[0045] Figure 6 is a photograph showing the titanium mesh of Example 2.

[0046] Figure 7 is a photograph showing the titanium mesh of Comparative Example 1.

[0047] Figure 8 is a photograph showing the titanium mesh of Comparative Example 2.

[0048] Figure 9 is a photograph showing the titanium mesh of Comparative Example 3.

[0049]

[0050] Hereinafter, the present invention will be described in more detail to facilitate understanding. The terms and words used in this specification and claims should not be interpreted based on their conventional or dictionary meanings. Based on the principle that the inventor can appropriately define the concepts of terms to best explain his or her invention, they should be interpreted in a way that aligns with the technical spirit of the present invention.

[0051] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0052] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0053]

[0054] separator

[0055] The present invention provides a separator comprising a metal plate including titanium; and a titanium mesh bonded to one surface of the metal plate, wherein the titanium mesh has a woven pattern, and the titanium mesh satisfies the following conditions 1 and 2.

[0056] [Condition 1]

[0057] The ratio of the empty space area on the side to the side area of ​​the unit mesh is 20% or more,

[0058] The lateral area of ​​the above unit mesh is calculated as (diameter + cross-section) × mesh thickness.

[0059] The above empty space area is an area formed by two wires having a rough shape through the above weaving pattern.

[0060] [Condition 2]

[0061] The ratio of the contact area to the area of ​​the unit mesh is 30% or more,

[0062] The above contact area refers to the area where the wire of the mesh comes into contact with the metal plate.

[0063] The separator of the present invention not only supplies or separates a reaction gas, but also serves to physically support a membrane electrode assembly when a water electrolysis cell is connected, and can also serve to discharge products and manage heat inside the cell through electrical conduction and electrochemical reaction.

[0064] Conventional separators used in electrochemical conversion devices such as electrolysis and fuel cells are made by individually laminating separate metal plates with formed channels, or by forming multiple channels on the surface facing the anode and the surface facing the cathode, respectively. The channels can transport various fluids to diffuse reactants into the catalyst layer. Furthermore, the oxygen evolution reaction of the anode and the hydrogen evolution reaction of the cathode can occur in the channels. However, in order to form the channels, the plates were manufactured by processing both the channels and the supply manifold into a disc, and specifically, the channels had to be formed through thin plate forming, stamping, or etching. Consequently, it was difficult to form the channels while maintaining a thin separator thickness. Furthermore, due to the processing characteristics such as thin plate forming or etching, it was difficult to form a consistent current collection area and cross-sectional area of ​​the channels. In addition, heat was applied to the disc, causing the disc to warp. These phenomena could ultimately cause imbalances in the transport of substances through the channels or increase electrical resistance, which could lower the efficiency of electrolysis. In addition, in conventional electrolytic separators, titanium and / or platinum coatings were used on inexpensive stainless steel materials, but there was also a problem that long-term operation was impossible due to corrosion and peeling of the deposited thin film.

[0065] Accordingly, the inventor of the present invention designed a separator with a thickness that can withstand a cathode pressurized environment while satisfying stack weight reduction, and replaced the channel by bonding a titanium mesh to one side of the separator to induce smooth material transfer without forming a separate channel in the active area of ​​the separator. In this way, by bonding a titanium mesh to one side of the separator, the cost and process consumed for processing the channel were reduced, and the titanium mesh was developed to improve electrolysis performance by making the material transfer smoother than the existing channel.

[0066] In addition, in the case of separators attached to conventional electrolysis and fuel cells, a mesh layer is laminated on one side of the separator and a gas diffusion layer is laminated on the other side to replace the flow path of the separator. However, the mesh used in the mesh layer generally has a lath shape or an expanded metal shape. This shape means that a flat plate is cut at continuous and regular intervals and extended sideways to form a net shape. Although this type of mesh has the advantage of increasing the contact area with other components of the cell, it has the disadvantage of making it difficult for fluid to pass or be transported to the side of the mesh due to the excessive contact area. This disadvantage ultimately caused a problem of deterioration in cell performance.

[0067] Accordingly, the present invention specifies the titanium mesh as a structure in which two wires have a weaving pattern, specifies the ratio of the empty space area per unit mesh and the contact area within the mesh having the weaving pattern, and bonds or welds the mesh to a metal plate, thereby enabling a low level of electrical resistance and improving cell performance by facilitating fluid transport.

[0068] The present invention includes a metal plate including titanium and a titanium mesh bonded to one surface of the metal plate. Since the bonded titanium mesh can replace the flow path of the separator, the separator of the present invention does not include a separate flow path. That is, the present invention does not require a separator having a separate flow path formed therein or a processing process for forming a separate flow path, so that a constant supply of reactants and yield of products can be achieved without processing errors in the flow path. In addition, when processing the flow path, a problem may arise in that the corner portion between the bottom and side of the flow path is formed in a curved / rounded shape rather than a right angle, such as a corner fillet, thereby reducing the contact area with the electrode and reducing the cross-sectional area of ​​the flow path, which may lower the electrolysis efficiency. However, the separator of the present invention does not have such a problem.

[0069] In addition, since the anode side corresponds to a humid environment where the supplied water is decomposed into oxygen gas, electrons, and hydrogen ions, the metal plate and mesh include titanium that is resistant to corrosion.

[0070] In addition, the titanium mesh is bonded to one side of a flat metal plate, where bonding means forming a single structure rather than simple lamination or adhesion. As a process for bonding, the metal plate and the titanium mesh can be bonded using methods such as ultrasonic welding or laser welding. Since the mesh and the metal plate are bonded to form a single separator, the electrical resistance is reduced compared to a structure in which separate meshes and separators are laminated when the cell is connected, thereby enabling an excellent level of electrolysis performance.

[0071] Fig. 2 illustrates a mesh structure (a) of the present invention. Referring to Fig. 2, the titanium mesh of the present invention has a woven pattern formed by interweaving two wires, each serving as a warp and a weft. Here, the woven pattern may have a form such as a plain weave or a twill weave, and may simultaneously satisfy conditions 1 and 2. The plain weave refers to a pattern in which the warp and weft are interweaved at right angles, so that the openings formed by the warp and weft have a square space of a uniform and constant size. In addition, the twill weave refers to a pattern in which two rows of weft and warp threads are interweaved with each other. The titanium mesh of the present invention has a woven pattern as described above, so that it can have a contact area of ​​a specific ratio and a void area of ​​a specific ratio, thereby enabling smooth transport and passage of a fluid and maintaining a low level of electrical resistance.

[0072] In the present invention, the above-mentioned slope means a wire arranged in a vertical direction, and the weft means a wire arranged in a horizontal direction.

[0073] Additionally, a unit mesh means an area that is the product of the horizontal length of one wire diameter and one opening and the same vertical length.

[0074] In addition, the above diameter refers to the diameter of the wires that constitute the mesh, and the above length refers to the length of one side of the empty area formed by the spacing of the wires (warp and weft) that constitute the mesh.

[0075] The titanium mesh of the present invention satisfies the following conditions 1 and 2.

[0076] [Condition 1]

[0077] The ratio of the lateral empty space area to the lateral area of ​​the unit mesh is 20% or more, and the lateral area of ​​the unit mesh is calculated as (wire diameter + individual mesh) × mesh thickness, and the empty space area is an area formed by two wires having a protruding shape by the weaving pattern.

[0078] [Condition 2]

[0079] The ratio of the contact area to the area of ​​the unit mesh is 30% or more, and the contact area means the area where the wire of the mesh excluding the opening comes into contact with the metal plate.

[0080] The above condition 1 specifies the ratio of the area of ​​the empty space, thereby enabling smooth transport and passage of the fluid. Specifically, the side area of ​​the unit mesh can be calculated as (wire diameter + cross section) Х mesh thickness, and referring to Fig. 3, it can be calculated as (wire diameter 1 / 2 + wire diameter 1 / 2 + cross section) Х mesh thickness. The above empty space area refers to a space formed when the warp and weft yarns are intertwined perpendicularly to each other, and this can be an area formed by having a rough shape when viewed from the side. In addition, the mesh thickness can be calculated as the wire diameter (diameter) of the warp yarn + the wire diameter (diameter) of the weft yarn.

[0081] The ratio of the empty space area of ​​the above condition 1 may be 20% or more, 21% or more, 23% or more, 25% or more, 27% or more, 29% or more, 30% or more, 35% or less, 34% or less, 33% or less, 32% or less, or 31% or less, and when the above range is satisfied, smooth transport and passage of the fluid on the mesh side may be possible, thereby improving the electrolysis reaction efficiency. In addition, when the ratio of the empty space area of ​​the above condition 1 exceeds 35%, smooth transport of the fluid may be good in terms of material transfer, but the contact area may be reduced, thereby lowering the electrolysis reaction efficiency.

[0082] The above condition 2 specifies the ratio of the contact area, through which the contact area with other components of the cell can be increased to maintain low electrical resistance. Here, the other components of the cell may include a metal plate or a porous diffusion layer. Referring to Fig. 4, specifically, the contact area means the area where the warp wire comes into contact with other components and the area where the weft wire comes into contact with other components. In addition, the area of ​​the unit mesh can be calculated as the horizontal (wire diameter + single row) length × vertical (wire diameter + single row) length of the unit mesh when the mesh is spread out and viewed from above.

[0083] The ratio of the contact area of ​​the above condition 2 may be 30% or more, 31% or more, 33% or more, 35% or more, 37% or more, 39% or more, 40% or more, 41% or more, 43% or more, 45% or more, 47% or more, 48% or more, 60% or less, 59% or less, 57% or less, or 55% or less, and when the above range is satisfied, the optimal contact area can be maintained to maintain a low level of electrical resistance. In addition, when the ratio of the contact area of ​​the above condition 2 exceeds 60%, the resistance can be reduced as the contact area increases, but there is a concern that the electrolysis reaction efficiency may be lowered because smooth transport of the fluid is difficult.

[0084] According to one embodiment of the present invention, the titanium mesh may not include a structure formed in a lath shape or an expanded metal shape. As described above, the titanium mesh of the present invention must have a structure formed by intertwining two wires as warp and weft, respectively, and the ratio of the empty space area and the contact area can be controlled through this structure. Since the lath shape or the expanded metal shape cannot generate empty spaces within the mesh, the titanium mesh of the present invention does not include a mesh in a lath shape or an expanded shape.

[0085]

[0086] According to one embodiment of the present invention, the thickness of the titanium mesh (200b) may be 0.2 mm or more and 1.0 mm or less. The thickness of the mesh is the sum of the diameters of two wires, and specifically, the mesh thickness may be calculated as the warp wire diameter (diameter) + the weft wire diameter (diameter). For example, the thickness of the titanium mesh (200b) may be 0.20 mm or more, 0.25 mm or more, 0.30 mm or more, 0.35 mm or more, 0.40 mm or more, 0.45 mm or more, 0.50 mm or more, 1.00 mm or less, 0.95 mm or less, 0.90 mm or less, 0.85 mm or less, 0.80 mm or less, 0.75 mm or less, 0.70 mm or less, 0.65 mm or less, or 0.60 mm or less. When the thickness of the titanium mesh (200b) satisfies the above numerical range, it can perform the role of an optimal flow path without forming a separate flow path on the metal plate, and can effectively discharge oxygen generated by the reaction through an optimal space area, so that the overvoltage can be reduced. In addition, since titanium generally has excellent strength, the processing and etching work for forming a flow path on a separator including titanium is difficult and requires cost and time. However, when the titanium mesh (200b) having the above thickness is brought into contact with the separator, it can replace the role of an excellent flow path, so that the supply and discharge of fluid can be smoothly performed, thereby reducing the overvoltage and increasing the electrolysis efficiency.

[0087] According to one embodiment of the present invention, the mesh number of the titanium mesh may be 10 mesh or more and 120 mesh or less. The mesh number refers to the number of meshes between 1 inch (25.4 mm). For example, the mesh number may be 10 mesh or more, 20 mesh or more, 30 mesh or more, 40 mesh or more, 50 mesh or more, 60 mesh or more, 70 mesh or more, 120 mesh or less, 110 mesh or less, 100 mesh or less, 90 mesh or less, or 80 mesh or less. When the mesh number is satisfied, smooth transport of fluid is possible while lowering the contact resistance, thereby improving mass transfer, and thereby improving the performance of the water electrolysis stack.

[0088]

[0089] According to one embodiment of the present invention, the metal plate may further include stainless steel, and the separator may be a clad metal plate including titanium and stainless steel. In addition, the clad metal plate may include a first layer (10) including titanium and a second layer (20) including stainless steel, and the thickness ratio of the first layer (10) and the second layer (20) may be 10:90 to 30:70. Specifically, the clad metal plate may be formed by integrally forming the first layer (10) including titanium and the second layer (20) including stainless steel by forced rolling. The clad metal plate refers to a plate including a material manufactured into a single metal through atomic diffusion bonding between dissimilar metals, and for example, refers to a plate including a single metal whose structure itself is stabilized as a whole by rolling titanium metal and stainless steel metal under strong pressure so that the mutual metal structures destroy each other's structures and penetrate each other. Accordingly, the separator including the clad metal plate of the present invention corresponds to a different material from the conventional separator in which two metal plates are simply bonded or laminated by means of bonding or welding, etc., and the clad metal plate of the present invention does not peel off even when left for a long time, but rather has a strong bonding force, so that it can be formed with a very thin thickness compared to a separator in which two or more separate separators are laminated. In addition, since each layer is hetero-bonded, an electrolysis cell can be configured with only one metal plate even in different environments of the positive electrode (cathode (300) and anode (400)), so that the interfacial resistance between the materials of the electric conversion device can be reduced, thereby improving the efficiency during electric conversion.

[0090] The above clad metal plate includes a first layer (10) containing titanium and a second layer (20) containing stainless steel, and the first layer (10) can face the anode (400) side when the cell is fastened, and the second layer (20) can face the cathode (300) side. Since the anode (400) side is in a humid environment where supplied water is decomposed into oxygen gas, electrons, and hydrogen ions, titanium, which is resistant to corrosion, is preferable.

[0091] According to one embodiment of the present invention, the thickness ratio of the first layer (10) and the second layer (20) may be 10:90 to 30:70. For example, it may be 10:90, 15:85, 20:80, 25:75, or 30:70, and specifically, it may be 15:85 to 25:75. When the thickness ratio of the first layer (10) and the second layer (20) satisfies the above range, the material cost, the cost of manufacturing the separator, and the cost of processing the flow path can be reduced, and at the same time, the corrosion resistance of the metal plate can be improved, the overvoltage can be reduced, and the electrolysis efficiency can be improved.

[0092] According to one embodiment of the present invention, the metal plate may further include an engineering plastic. Here, the engineering plastic is a plastic with excellent heat resistance, mechanical strength, and elasticity, and may have the advantage of being lighter than existing metal and ceramic materials, thereby contributing to weight reduction of the product. For example, the engineering plastic may include one or more materials selected from the group consisting of polyphenylene sulfide (PPS), polyphenylene sulfone (PPSU), polysulfone (PSU, Polyarylsulfones), and polyether ether ketone (PEEK).

[0093] In the case of the metal plate of the present invention, it may include a titanium metal material, or a clad metal material including titanium and stainless steel, and further, the active area of ​​the metal plate may be made of a metal material, and an area portion other than the active area may include the engineering plastic material. In the case of including the engineering plastic material, it may have the advantage of having excellent heat resistance and acid resistance, so that performance degradation due to the external environment during electrolysis operation can be suppressed, and long-term operation is possible.

[0094]

[0095] According to one embodiment of the present invention, the thickness of the metal plate may be 0.1 mm or more and 5.0 mm or less. For example, the thickness of the metal plate may be 0.1 mm or more, 0.3 mm or more, 0.5 mm or more, 0.7 mm or more, 0.9 mm or more, 1.0 mm or more, 1.3 mm or more, 1.5 mm or more, 1.7 mm or more, 1.9 mm or more, 2.0 mm or more, 2.3 mm or more, 2.5 mm or more, 5.0 mm or less, 4.9 mm or less, 4.7 mm or less, 4.5 mm or less, 4.3 mm or less, 4.1 mm or less, 4.0 mm or less, 3.7 mm or less, 3.5 mm or less, 3.3 mm or less, 3.1 mm or less, 3.0 mm or less, and specifically, the thickness of the metal plate may be 2.0 mm or more and 5.0 mm or less. When the thickness of the metal plate satisfies the above range, it is possible to form a thin thickness while maintaining excellent durability and physical strength, so that the fastening pressure can be withstood when the electrolysis stack is fastened, thereby improving the fastening property, and accordingly, the interfacial resistance between different components within each cell can be reduced, thereby improving the electrolysis efficiency.

[0096]

[0097] Electrolysis cells and electrolysis stacks

[0098] The present invention provides a water electrolysis cell comprising a first separator (100) and a second separator (200) according to the present invention as described above; and a membrane electrode assembly comprising an anode (400), a separator (500), and a cathode (300) disposed between the first separator (100) and the second separator (200).

[0099] The first separator (100) and the second separator (200) of the present invention may include a metal plate containing titanium, as described above, and a titanium mesh bonded to one surface of the metal plate. Here, the first and second are for distinguishing between a separator arranged on the anode (400) side of the membrane electrode assembly and a separator arranged on the cathode (300) side, and the first separator (100) and the second separator (200) may be made of the same or different materials and thicknesses.

[0100] In addition, according to one embodiment of the present invention, the electrolysis cell of the present invention may include a gas diffusion layer (600) disposed between the cathode (300) and the first separator (100), and a porous diffusion layer (700) disposed between the anode (400) and the second separator (200).

[0101] Referring to FIG. 1, the basic structure of the electrolysis cell of the present invention may be a structure in which a first separator (100) - gas diffusion layer (600) - cathode (300) - separator (500) - anode (400) - porous diffusion layer (700) - second separator (200) are sequentially laminated, and the first separator (100) and the second separator (200) do not include a flow path, and the second separator may be a titanium metal plate (220a) having a titanium mesh (200b) welded to one surface thereof. Here, the first separator may also have a structure in which a titanium metal plate and a titanium mesh are joined, and in FIG. 1, the structure in which the titanium mesh is joined to the first separator is omitted in order to express a unit cell.

[0102] According to one embodiment of the present invention, the porous diffusion layer (700) may include titanium felt. The porous diffusion layer (700) can assist in the function of the titanium mesh as a flow path and can improve the contact force between the separator and the membrane electrode assembly when the electrolysis cell is connected. Specifically, by reducing the gap between the separator and the membrane electrode assembly, the processing error occurring during the electrolysis cell processing can be absorbed. In addition, the porous diffusion layer (700) can play a role in reducing battery resistance and overvoltage by making good contact with the catalyst layer of the anode (400).

[0103] According to one embodiment of the present invention, the thickness of the porous diffusion layer (700) may be 200 ㎛ or more and less than 450 ㎛, and for example, 200 ㎛ or more, 210 ㎛ or more, 220 ㎛ or more, 230 ㎛ or more, 240 ㎛ or more, 250 ㎛ or more, 260 ㎛ or more, 270 ㎛ or more, 280 ㎛ or more, 290 ㎛ or more, 300 ㎛ or more, less than 450 ㎛, 440 ㎛ or less, 430 ㎛ or less, 420 ㎛ or less, 410 ㎛ or less, 400 ㎛ or less, 390 ㎛ or less, 380 ㎛ or less, 370 ㎛ or less, 360 ㎛ or less, and 350 ㎛ or less. Specifically, the thickness of the porous diffusion layer (700) may be 200 μm or more and 300 μm or less. When the porous diffusion layer (700) satisfies the above numerical range, an optimal space area can be formed to effectively discharge oxygen gas generated through the reaction, and the overall thickness of the water electrolysis cell can be reduced to reduce electrical resistance, thereby achieving a high level of electrolysis efficiency.

[0104] According to one embodiment of the present invention, the thickness of the gas diffusion layer (600) may be 150 ㎛ or more and 400 ㎛ or less. The gas diffusion layer (600) may be disposed between the cathode (300) side and the separator, and may serve as a path so that hydrogen ions that have passed through the separator (500) may be smoothly discharged as hydrogen gas. The gas diffusion layer (600) may include a porous substrate including a carbon material such as carbon fiber cloth, carbon fiber felt, or oxygen fiber paper, or a metal porous body formed of a thin separator having a mesh structure such as expanded metal or metal mesh. The thickness of the above gas diffusion layer (600) may be 200 ㎛ or more, 210 ㎛ or more, 220 ㎛ or more, 230 ㎛ or more, 240 ㎛ or more, 250 ㎛ or more, 260 ㎛ or more, 270 ㎛ or more, 280 ㎛ or more, 290 ㎛ or more, 300 ㎛ or more, 310 ㎛ or more, 320 ㎛ or more, 330 ㎛ or more, 400 ㎛ or less, 390 ㎛ or less, 380 ㎛ or less, 370 ㎛ or less, 360 ㎛ or less, 350 ㎛ or less, or 330 ㎛ or less. Specifically, the thickness of the gas diffusion layer (600) may be 210 ㎛ or more and 330 ㎛ or less, and when the thickness is satisfied, smooth discharge of hydrogen gas is possible without excessive thickness increase, and electrolysis efficiency can be increased by reducing electrical resistance.

[0105] According to one embodiment of the present invention, the area of ​​the separator is 100 cm 2 Above 5000 cm 2 It may be less than or equal to 100 cm. For example, the area of ​​the separator is 100 cm. 2 Ideal, 200 cm 2 Ideal, 300 cm 2 Ideal, 500 cm 2 Ideal, 700 cm 2 Above, 1000 cm 2 Above, 1200 cm 2 Ideal, 1500 cm 2 Ideal, 1700 cm 2Ideal, 2000 cm 2 Above, 5000 cm 2 Below, 4500 cm 2 Below, 4000 cm 2 Below, 3500 cm 2 Below, 3000 cm 2 Below, 2500 cm 2 It could be as follows:

[0106] In the case of fuel cells, since they are actually used in automobiles, etc., there are aspects that make it difficult to form them into large-area electrochemical cells or stacks considering the specifications when used. However, in the case of cells or stacks included in electrolysis devices, they can be formed into large areas in order to increase the amount of water or carbon dioxide converted per unit time. At this time, in the case of electrolysis cells or stacks, it is important to maintain a large area for a long time while maintaining physical / chemical durability and high electrolysis efficiency. However, as the electrode area of ​​the cell or stack increases, the area of ​​the applied separator also increases. If a separator with a separate flow path is laminated on such a large-area separator or manufactured through a separate processing process to form the flow path, the supply and demand of the required mold machine and the difficulty of processing increase. In particular, processing errors may occur in the molding for flow path formation, and a peeling phenomenon may occur due to long-term storage.

[0107] On the other hand, the separator of the present invention uses a titanium metal plate or a clad metal plate including a titanium layer and a stainless steel layer, and includes a titanium mesh (200b) bonded to one surface of the metal plate, so that no separate processing is required, it is easy to manufacture a large-area separator, and it has physical durability and prevents peeling when left for a long period of time, and reduces interfacial resistance through a thin thickness.

[0108]

[0109] According to one embodiment of the present invention, the separator and membrane electrode assembly can be utilized in all electrochemical conversion devices, and the electrochemical conversion devices can include devices capable of producing useful chemical substances through electrochemical conversion such as water electrolysis, carbon dioxide electrolysis, and fuel cells, and devices capable of being utilized for reducing and converting carbon dioxide and NOx.

[0110] In addition, according to one embodiment of the present invention, the anode (400) may be arranged in contact with the porous diffusion layer (700), and the cathode (300) may be arranged in contact with the gas diffusion layer (600). The porous diffusion layer (700) may be arranged on the anode (400) side to serve as a flow path, and the gas diffusion layer (600) may be arranged on the cathode (300) side to serve as a flow path.

[0111] The above electrolysis refers to decomposing a substance through a redox reaction by applying a direct current voltage to a decomposition reaction that does not occur spontaneously. The anode acts as an oxidation electrode and oxidizes water to generate oxygen, which in turn generates hydrogen ions. The hydrogen ions generated at the anode are transferred to the cathode through the separator, and the cathode acts as a reduction electrode and can react with the electrons and hydrogen ions transferred from the anode to generate a product. In addition, the separator may be disposed between the anode and the cathode. The separator may be composed of an inert material that does not participate in the electrochemical reaction itself, but provides a path for ions to move between the anode and the cathode and may serve to isolate physical contact between the anode and the cathode. The separator may be a polymer electrolyte membrane, and may be formed of, for example, a solid polymer having a thickness of about 50 μm to 200 μm, and enables ion exchange that transfers hydrogen ions generated at the catalyst layer of the anode to the catalyst layer of the cathode.

[0112] According to one embodiment of the present invention, the anode is a part that receives water (H2O), and when electricity is applied to the electrode catalyst layer, the water is electrolyzed to generate oxygen, hydrogen ions, and electrons. It may include a catalyst active in the electrolysis of water, and the catalyst layer of the anode may include at least one selected from the group consisting of Pt, Au, Pd, Ir, Ag, Rh, Ru, Ni, Al, Mo, Cr, Cu, Ti, W, alloys thereof, or mixed metal oxides, for example, RuO2, IrO2, etc. for an oxygen generation reaction. In addition, the catalyst layer of the anode may form a core-shell structure, and the core particles may include TiO2 or Nb, and the shell particles may include RuO2 or IrO2.

[0113] The cathode is a hydrogen-generating portion between the separator and the membrane electrode assembly, where hydrogen ions transferred from the anode in the electrode catalyst layer combine with electrons transferred through an external circuit to produce pure hydrogen. This cathode may be made of a material known in the art, such as platinum (Pt), platinum-supported carbon (Pt / C), etc.

[0114] According to one embodiment of the present invention, the gasket may include a first gasket disposed between the anode (400) and the separator, and a second gasket (900) disposed between the cathode (300) and the separator, wherein the first gasket may be disposed to surround side surfaces of the titanium mesh layer (200b) and the porous diffusion layer (700), and the second gasket may be disposed to surround side surfaces of the gas diffusion layer. Specifically, the first gasket may be positioned on the anode (400) side, and the second gasket may be positioned on the cathode (300) side.

[0115] The above gasket (900) can prevent reactants or products from flowing out of the device through a corresponding path or mixing within the device through different paths when operating an electrolysis cell including the above separator. In other words, the gasket (900) can serve to prevent reactants or products from flowing into areas other than the designated path.

[0116] Conventional gaskets are made of rubber or elastic material in the form of a thin plate and laminated on one side of the separator. In this case, if the area of ​​the gasket increases or the number of laminates increases, the gasket may be compressed unevenly, causing a phenomenon in which reactants or products leak out.

[0117] The electrolysis cell of the present invention may include a gasket (900) in a line shape rather than a surface shape to solve the conventional problems. The gasket (900) of the present invention may be formed in a structure that surrounds and separates an area including the flow path, and a plurality of line-shaped gaskets (900) may be formed in two or three or more layers.

[0118]

[0119] The present invention provides a water electrolysis stack comprising a plurality of water electrolysis cells according to the present invention described above. The water electrolysis cell of the present invention may be a single unit cell in which a first separator (100) - a gas diffusion layer (600) - a membrane electrode assembly - a porous diffusion layer (700) - a second separator (200) are laminated and fastened, and a plurality of unit cells may be laminated and fastened to form a single water electrolysis stack.

[0120]

[0121] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0122]

[0123] Example 1

[0124] An anode catalyst ink composition was prepared by mixing 1 g of IrO2 catalyst (Tanaka Corporation), 0.76 g of commercial Nafion dispersion (Chemours Corporation nafionTM PFSA Polymer Dispersions D2020CS), which is an ion-conducting binder resin, 1.94 g of 1-propanol (NPA) solvent, and 0.7 g of DI water.

[0125] A cathode catalyst ink composition was prepared by mixing 1 g of platinum catalyst (Pt / C) (Tanaka) supported on carbon black, 1.85 g of commercial Nafion dispersion (Chemours nafionTM PFSA Polymer Dispersions D2020CS), which is an ion-conducting binder resin, 5.2 g of 1-propanol (NPA) solvent, and 2 g of DI water.

[0126] As a separator, commercial Nafion film (Chemours nafionTM N115, 127 ㎛) was cut into 85 mm × 85 mm sizes and used.

[0127] The cathode catalyst ink composition was coated on one side of the separator using a slot die method to form a cathode catalyst layer having a thickness of 5 μm, and the anode catalyst ink composition was coated on the other side of the separator using a slot die method to form an anode catalyst layer having a thickness of 3 μm, thereby forming an active area of ​​25 cm 2 of A membrane electrode assembly was manufactured.

[0128] After this, the first separator-gas diffusion layer-membrane electrode assembly (cathode-separator-anode)-porous diffusion layer-second separator were sequentially stacked and the electrolysis cell was fastened with a fastening pressure of 4 MPa. Here, the first and second separators were used by welding a woven titanium mesh (mesh number: 40 mesh, thickness: 470 ㎛, wire diameter 190 um product) to one side of a metal plate containing 100% titanium, having no flow path and a thickness of 1 mm, and joining the metal plate and the mesh.

[0129] The porous diffusion layer used was a Bekaert product with a thickness of 250 μm and a Pt plating, and the gas diffusion layer used SGL's 39BB (thickness: 320 μm).

[0130]

[0131] Example 2

[0132] A water electrolysis cell was assembled in the same manner as in Example 1, except that a woven titanium mesh having a mesh count of 80 mesh, a thickness of 230 ㎛, and a wire diameter of 190 um was used instead of the woven titanium mesh (mesh count: 40 mesh, thickness: 470 ㎛, wire diameter 190 um product) in Example 1.

[0133]

[0134] Example 3

[0135] A water electrolysis cell was assembled in the same manner as in Example 1, except that a woven titanium mesh having a mesh count of 20 mesh, a thickness of 750 ㎛, and a wire diameter of 190 um was used instead of the woven titanium mesh (mesh count: 40 mesh, thickness: 470 ㎛, wire diameter 190 um product) in Example 1.

[0136]

[0137] Comparative Example 1

[0138] A water electrolysis cell was assembled in the same manner as in Example 1, except that a titanium mesh with a thickness of 520 μm in a lath shape was used instead of the woven titanium mesh (mesh number: 40 mesh, thickness: 470 μm, wire diameter 190 μm product) in Example 1.

[0139]

[0140] Comparative Example 2

[0141] A water electrolysis cell was assembled in the same manner as in Example 1, except that a titanium mesh with a thickness of 920 μm in a lath shape was used instead of the woven titanium mesh (mesh number: 40 mesh, thickness: 470 μm, wire diameter 190 μm product) in Example 1.

[0142]

[0143] Comparative Example 3

[0144] A water electrolysis cell was assembled in the same manner as in Example 1, except that a woven titanium mesh having a mesh count of 8 mesh, a thickness of 850 ㎛, and a wire diameter of 190 um was used instead of the woven titanium mesh (mesh count: 40 mesh, thickness: 470 ㎛, wire diameter 190 um product) in Example 1.

[0145]

[0146] Comparative Example 4

[0147] A water electrolysis cell was assembled in the same manner as in Example 1, except that a woven titanium mesh having a mesh count of 150 mesh, a thickness of 160 ㎛, and a wire diameter of 190 ㎛ was used instead of the woven titanium mesh (mesh count: 40 mesh, thickness: 470 ㎛, wire diameter 190 um product) in Example 1.

[0148]

[0149] Comparative Example 5

[0150] A water electrolysis cell was assembled in the same manner as in Example 1, except that instead of welding a woven titanium mesh (mesh count: 40 mesh, thickness: 470 ㎛, wire diameter: 190 um product) to one side of the metal plate, a metal plate and titanium mesh were laminated and used.

[0151]

[0152] Experimental Example 1

[0153] The ratios of the void area and contact area of ​​the titanium mesh used in the electrolysis cell fastening of the above examples and comparative examples were measured. The void area and contact area were measured and calculated based on the specifications of the mesh's open area and wire diameter.

[0154] Specifically, the above empty space area is expressed as a ratio of the area through which the fluid passes to the entire lateral area of ​​the titanium mesh. The open area of ​​one unit mesh section according to the opening and the diameter was measured, and then the empty space area was derived by dividing it by the lateral unit mesh area.

[0155] In addition, the above contact area is expressed as a ratio of the remaining area after subtracting the opening area from the total front surface area of ​​the titanium mesh. The contact area was derived by calculating the remaining area after subtracting the opening area from 1 unit mesh section and dividing it by the front unit mesh area. The measured results are shown in Table 1 below.

[0156]

[0157] Experimental Example 2

[0158] For the electrolysis cells according to the above examples and comparative examples, cell performance measurements were conducted. Specifically, 25 cm 2 The unit cell was fabricated and the flow rate was 60 mL / min, the operating temperature was 70 ℃, and the potentiostat was 0.3 A / cm using the HCP-803 Potentiostat from biologic.2 30 min at a constant current of 1.5 A / cm 2 After 30 minutes of activation at constant current, the performance of the electrolysis cell was measured using Linear Sweep Voltammetry (LSV). The measured results are shown in Table 1 below.

[0159] ClassificationMesh structure / Number of meshes / Thickness (㎛)Presence of bonding (welding)Void space areaContact areaNumber of electrolytic cell performance (A)(>1.9A@1.9V or more)Judging whether it is 90% or more of the maximum performance standardExample 1 Woven / 40 / 470○25%52%2.50OKExample 2 Woven / 80 / 230○27%48%2.41OKExample 3 Woven / 20 / 750○29%43%2.33OKComparative example 1 Lath○13%55%1.83NGComparative example 2 Lath○18%48%2.21NGComparative example 3 Woven / 8 / 850○37%26%1.73NGComparative example 4 Woven / 150 / 160○15%62%2.04NGComparative example 5 weave / 40 / 470X25%52%2.18NG

[0160] Actual photographs of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in FIGS. 5 to 9. In the case of Comparative Examples 1 and 2, it can be confirmed that they are in a lath shape, and it can be confirmed that Comparative Example 3 has a considerably small number of meshes. Referring to Table 1 above, Examples 1 to 3 form a single separator by welding and joining a titanium mesh having a woven pattern on one side of a titanium metal plate according to the present invention, and the titanium mesh satisfies the empty space area and contact area according to the present invention, so that the cost and process of processing the separator according to the formation of a flow path can be reduced, and it can be confirmed that the current value according to the 1.9 V voltage condition exceeds 1.9 A, so that it has excellent cell performance.

[0161] In contrast, Comparative Examples 1 and 2 used a titanium mesh in a lath shape rather than a woven shape. In this case, the area of ​​passage through the flow path is significantly reduced, so it is predicted that the transport and passage of the fluid will not be smooth, and as a result, it can be confirmed that the cell performance is also at an inferior level.

[0162] In addition, Comparative Example 3 used a titanium mesh that was outside the contact area range of the present invention, Comparative Example 4 used a titanium mesh that was outside the void area range of the present invention, and Comparative Example 5 used a titanium mesh that was simply laminated when fastening the cell rather than welding and joining it on a metal plate. It can be confirmed that all of Comparative Examples 3 to 5 did not satisfy Conditions 1 and 2 of the present invention or were not joined, resulting in inferior cell performance.

[0163] 100: First separator

[0164] 200: Second Separator

[0165] 200a: Metal plate

[0166] 200b: Titanium mesh

[0167] 300: Cathode

[0168] 400: Anode

[0169] 500: Membrane

[0170] 600: Gas diffusion layer

[0171] 700: Porous diffusion layer

[0172] 900: Gasket

Claims

1. A metal plate containing titanium; and a titanium mesh bonded to one surface of the metal plate, The above titanium mesh is a woven pattern, The above titanium mesh is a separator that satisfies the following conditions 1 and 2. [Condition 1] The ratio of the empty space area on the side to the side area of ​​the unit mesh is 20% or more, The lateral area of ​​the above unit mesh is calculated as (diameter + cross-section) × mesh thickness. The above empty space area is an area formed by two wires having a rough shape through the above weaving pattern. [Condition 2] The ratio of the contact area to the area of ​​the unit mesh is 30% or more, The above contact area refers to the area where the wire of the mesh comes into contact with the metal plate.

2. In claim 1, A separator having a thickness of the above titanium mesh of 200 ㎛ or more and 800 ㎛ or less.

3. In claim 1, A separator plate in which the mesh number of the above titanium mesh is 10 mesh or more and 120 mesh or less.

4. In claim 1, A separator plate wherein the metal plate further comprises stainless steel, and the metal plate is a clad metal plate comprising titanium and stainless steel.

5. In claim 4, A separator plate wherein the clad metal plate comprises a first layer comprising titanium and a second layer comprising stainless steel, and the thickness ratio of the first layer and the second layer is 10:90 to 30:

70.

6. In claim 1, A separator plate wherein the above metal plate further comprises engineering plastic.

7. In claim 6, A separator plate wherein the above engineering plastic comprises at least one material selected from the group consisting of polyphenylene sulfide, polyphenylene sulfone, polysulfone, and polyether ether ketone.

8. In claim 1, A separator plate in which the above titanium mesh does not include a structure formed in the form of a lath or expanded metal.

9. In claim 1, A separator plate having a thickness of the above metal plate of 0.1 mm or more and 5 mm or less.

10. In claim 1, The above separator is a separator that does not include a euro.

11. The first separator and the second separator according to claim 1; and A water electrolysis cell comprising a membrane electrode assembly including an anode, a separator, and a cathode disposed between the first separator and the second separator.

12. In claim 11, A gas diffusion layer disposed between the cathode and the first separator, A water electrolysis cell comprising a porous diffusion layer disposed between the anode and the second separator.

13. In claim 12, The thickness of the above gas diffusion layer is 150 ㎛ or more and 400 ㎛ or less, A water electrolysis cell wherein the thickness of the porous diffusion layer is 200 ㎛ or more and less than 450 ㎛.

14. A water electrolysis stack comprising a plurality of water electrolysis cells according to claim 1.

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