Water electrolysis cell and water electrolysis stack comprising same

Abstract

The present invention relates to a water electrolysis cell comprising: a separation plate including a first separation plate and a second separation plate; a membrane electrode assembly disposed between the first separation plate and the second separation plate and including an anode, a separation membrane, and a cathode; a gas diffusion layer disposed between the cathode and the first separation plate; a porous diffusion layer disposed between the anode and the second separation plate; and a titanium mesh layer, wherein the separation plate includes titanium, and the titanium mesh layer is not included between the cathode and the first separation plate.

Description

Electrolysis cell and electrolysis stack including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2024-0056020, filed April 26, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] Technology field

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

[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). Among these, alkaline electrolysis uses an alkaline electrolyte to electrolyze water and is the most commercially available technology. Alkaline electrolysis has the advantages of relatively low process operation 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-temperature 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 for the bipolar plate.

[0010] (Patent Document 1) KR 10-2123840 B1

[0011]

[0012] The problem to be solved by the present invention is to provide a separator having an excellent level of electrolytic performance, minimizing the thickness of the separator, reducing the process and cost required for processing the separator by including a member that replaces the flow path without a separate processing operation for forming the flow path in the separator.

[0013]

[0014] The present invention provides a water electrolysis cell and a water electrolysis stack.

[0015] (1) The present invention provides a water electrolysis cell comprising a membrane electrode assembly including a first separator and a second separator, an anode disposed between the first separator and the second separator, a separator, and a cathode, a gas diffusion layer disposed between the cathode and the first separator, a porous diffusion layer disposed between the anode and the second separator, and a titanium mesh layer, wherein the separator comprises titanium and does not include a titanium mesh layer between the cathode and the first separator.

[0016] (2) The present invention provides a water electrolysis cell in (1) above, wherein the titanium mesh layer is arranged in contact with one surface of the second separator.

[0017] (3) The present invention provides a water electrolysis cell according to (1) or (2), wherein the separator further comprises stainless steel, and the separator is a clad separator comprising titanium and stainless steel.

[0018] (4) The present invention provides a water electrolysis cell according to (3), wherein the clad separator 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.

[0019] (5) The present invention provides a water electrolysis cell according to any one of the above (1) to (4), wherein the separator further comprises an engineering plastic.

[0020] (6) The present invention provides a water electrolysis cell according to (5), wherein the engineering plastic comprises at least one material selected from the group consisting of polyphenylene sulfide, polyphenylene sulfone, polysulfone, and polyether ether ketone.

[0021] (7) The present invention provides a water electrolysis cell according to any one of the above (1) to (6), wherein the separator does not include a flow path.

[0022] (8) The present invention provides a water electrolysis cell according to any one of the above (1) to (7), wherein the thickness of the separator is 0.1 mm or more and 5.0 mm or less.

[0023] (9) The present invention provides a water electrolysis cell in any one of the above (1) to (8), wherein the thickness of the titanium mesh layer is 0.2 mm or more and 1 mm or less.

[0024] (10) The present invention provides a water electrolysis cell according to any one of the above (1) to (9), wherein the thickness of the porous diffusion layer is 200 ㎛ or more and less than 450 ㎛.

[0025] (11) The present invention provides a water electrolysis cell according to any one of the above (1) to (10), wherein the porous diffusion layer includes titanium felt.

[0026] (12) The present invention provides a water electrolysis cell according to any one of the above (1) to (11), wherein the thickness of the gas diffusion layer is 150 ㎛ or more and 400 ㎛ or less.

[0027] (13) The present invention provides a water electrolysis stack including a plurality of water electrolysis cells according to any one of (1) to (12) above.

[0028]

[0029] According to the electrolysis cell of the present invention, a separate flow path is not formed in the separator, and the structure replaces the flow path with a specific member, thereby reducing the process and cost required for flow path processing, and the titanium mesh layer of the anode is improved to lower the contact resistance and ensure smooth material transfer, thereby enabling an excellent level of electrolysis cell performance.

[0030]

[0031] Figure 1 is a cross-sectional view showing the separator structure of Example 1.

[0032] Figure 2 is a cross-sectional view showing the separator structure of Example 2.

[0033] Figure 3 is a graph showing the electrolysis performance of examples and comparative examples.

[0034]

[0035] 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.

[0036] 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.

[0037] In this specification, it should be understood that terms such as “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.

[0038]

[0039] Electrolysis cells and electrolysis stacks

[0040] The present invention provides a water electrolysis cell comprising a membrane electrode assembly including a first separator (100) and a second separator (200), an anode (400), a separator (500), and a cathode (300) disposed between the first separator (100) and the second separator (200), a gas diffusion layer (600) disposed between the cathode (300) and the first separator (100), a porous diffusion layer (700) disposed between the anode (400) and the second separator (200); and a titanium mesh layer (800), wherein the separator includes titanium and does not include the titanium mesh layer (800) between the cathode (300) and the first separator (100).

[0041] The separator included in the electrolysis cell of the present invention may include a first separator (100) and a second separator (200), and 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.

[0042] The separator of the present invention not only serves to supply or separate the reaction gas, but also serves to physically support the membrane electrode assembly when the electrolysis cell is connected, and also serves to discharge products through electrical conduction and electrochemical reaction and manage heat inside the cell.

[0043] 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 coating was used on inexpensive stainless steel material, but there was also a problem that long-term operation was impossible due to corrosion and peeling of the deposited thin film.

[0044] 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 disposing a titanium mesh layer (800) on one surface of the separator to induce smooth material transfer without forming a separate channel in the active area of ​​the electrolysis separator. In this way, by disposing the titanium mesh layer (800) on one surface of the separator, the cost and process consumed for processing the channel are reduced, and the titanium mesh layer (800) improves the electrolysis performance by making the material transfer smoother than the existing channel, thereby developing a water electrolysis cell and a water electrolysis stack including the same.

[0045] 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) - titanium mesh layer (800) - second separator (200) are sequentially laminated, and the first separator (100) and the second separator (200) do not include a flow path, and a titanium mesh layer (800) is included on one surface of the second separator (200). Specifically, a titanium mesh layer (800) and a porous diffusion layer (700) are included between the anode (400) and the second separator (200), and a gas diffusion layer (600) is included between the cathode (300) and the first separator (100). More specifically, the titanium mesh layer (800) may be arranged in contact with one surface of the second separator (200), and as a result, the titanium mesh layer (800) and the porous diffusion layer (700) may be sequentially laminated from the second separator (200) to the anode (400).

[0046] In addition, the separator of the present invention does not include a separate flow path, and the titanium mesh layer (800) and the gas diffusion layer (600) replace the flow path. Specifically, the titanium mesh layer (800) is arranged between the anode (400) and the second separator (200) when the electrolysis cell is connected, so that it can replace the flow path of the second separator (200), and the gas diffusion layer (600) is arranged between the cathode (300) and the first separator (100), so that it can replace the flow path of the first separator (100). 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 acquisition of products are possible without processing errors in the flow path. In addition, when processing the euro, there may be a problem that the corner portion between the bottom and side of the euro is formed in a curved / round shape rather than a right angle, such as a corner fillet, which reduces the contact area with the electrode and reduces the cross-sectional area of ​​the euro, thereby lowering the electrolysis efficiency. However, in the case of the separator of the present invention, such a problem does not occur.

[0047] In addition, the electrolysis cell of the present invention does not include a separate titanium mesh layer (800) between the first separator (100) and the cathode (300). Specifically, the titanium mesh layer (800) is disposed only on one side of the second separator (200) facing the anode (400), and is not disposed on one side of the first separator (100) facing the cathode (300). Since only hydrogen gas is generated and discharged on the cathode (300) side, only the gas diffusion layer (600) can be disposed to replace the role of the flow path. Rather, when the titanium mesh layer (800) is laminated in addition to the gas diffusion layer (600) on the cathode (300) side, the electrolysis cell thickness increases, which increases electrical resistance and may lower electrolysis efficiency.

[0048] According to one embodiment of the present invention, the separator may further include stainless steel, and the separator may be a clad separator including titanium and stainless steel. In addition, referring to FIG. 2, the clad separator 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 separator 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 separator 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 separator of the present invention corresponds to a different material from a conventional separator in which two metal plates are simply bonded or laminated by means of bonding or welding, etc., and the clad separator of the present invention does not peel off even when left for a long time, but rather has a stronger 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 separator 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.

[0049] The above clad separator comprises a first layer (10) comprising titanium and a second layer (20) comprising stainless steel, wherein the first layer (10) can face the anode (400) side when the cell is connected, 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.

[0050] 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 separator can be improved and the overvoltage can be reduced, thereby improving the electrolysis efficiency.

[0051] According to one embodiment of the present invention, the separator may further include an engineering plastic. Here, the engineering plastic is a plastic with excellent heat resistance, mechanical strength, and elasticity, and may have an advantage in reducing the weight of the product because it is lighter than existing metal and ceramic materials. 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).

[0052] In the case of the above separator 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 separator 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 it can suppress performance degradation due to the external environment during electrolysis operation, and it can have the advantage of being able to operate for a long period of time.

[0053] According to one embodiment of the present invention, the thickness of the separator may be 0.1 mm or more and 5.0 mm or less. For example, the thickness of the separator 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 separator 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 during the manufacture of the electrolysis device, thereby improving the fastening property, and accordingly, the interfacial resistance between components within each of the devices can be reduced, thereby improving the electrolysis efficiency.

[0054] According to one embodiment of the present invention, the thickness of the titanium mesh layer (800) may be 0.2 mm or more and 1.0 mm or less. Specifically, the thickness of the titanium mesh layer (800) 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 layer (800) satisfies the above numerical range, it can perform the role of a sufficient flow path without forming a separate flow path in the separator, and can effectively discharge oxygen generated by the reaction through an optimal space area, so that overvoltage can be reduced. In addition, since titanium generally has excellent strength, the processing and etching work for forming a flow path in a separator including titanium is difficult and requires high cost and time, but when a titanium mesh layer (800) having the above thickness is brought into contact with the separator, it can act as an excellent flow path, so that the supply and discharge of fluid can be smoothly performed, thereby reducing overvoltage and increasing electrolysis efficiency.

[0055] 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).

[0056] 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.

[0057] 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.

[0058] 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:

[0059] 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.

[0060] On the other hand, the separator of the present invention uses a titanium separator or a clad separator including a titanium layer and a stainless steel layer, and includes a titanium mesh layer (800) on the surface of the separator without performing a separate flow path processing, so that it is easy to manufacture a large-area separator, has physical durability, prevents peeling when left for a long period of time, and reduces interfacial resistance through a thin thickness.

[0061]

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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 disposed between the cathode (300) and the separator, wherein the first gasket may be disposed to surround side surfaces of the titanium mesh layer (800) 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071]

[0072] 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 titanium mesh layer (800) - 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.

[0073]

[0074] 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.

[0075]

[0076] Example 1

[0077] The anode catalyst composition was prepared by mixing 1 g of Ir catalyst, 0.76 g of commercial Nafion dispersion (Chemours nafionTM PFSA Polymer Dispersions D2020CS) as an ion-conducting binder resin, 1.94 g of 1-propanol (NPA) solvent, and 0.7 g of DI water to prepare an anode catalyst ink composition. The cathode catalyst composition was prepared by mixing 1 g of platinum catalyst (Pt / C) supported on carbon black, 1.85 g of commercial Nafion dispersion (Chemours nafionTM PFSA Polymer Dispersions D2020CS) as an ion-conducting binder resin, 5.2 g of 1-propanol (NPA) solvent, and 2 g of DI water to prepare a cathode catalyst ink composition. As a separator, commercially available Nafion film (Chemours nafionTM N115, 127 ㎛) was cut into 160 mm × 130 mm sizes and used.

[0078] 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 ​​100 cm 2 of A membrane electrode assembly was manufactured.

[0079] After this, the first separator-gas diffusion layer-membrane electrode assembly (cathode-separator-anode)-porous diffusion layer-titanium mesh layer-second separator were sequentially stacked and the electrolysis cell was fastened with a fastening pressure of 4 MPa. At this time, the first and second separators used contained 100% titanium content without forming a flow path and had a thickness of 1 mm. The gas diffusion layer (Bekaert, 2GDL1ON-026) had a thickness of 260 ㎛. The porous diffusion layer (SGL, 39BB) had a thickness of 320 ㎛. The titanium mesh layer (40 mesh, wire diameter 190 um product) had a thickness of 470 ㎛.

[0080]

[0081] Example 2

[0082] An electrolysis cell was assembled in the same manner as in Example 1, except that instead of using the first and second separators having a thickness of 1 mm and a titanium content of 100% in Example 1, first and second clad separators having a thickness of 1 mm and a titanium content of 20% and a stainless steel (SUS316L) content of 80% without forming a flow path were used.

[0083]

[0084] Comparative Example 1

[0085] A membrane electrode assembly was manufactured in the same manner as in Example 1. Thereafter, a water electrolysis cell was assembled in the same manner as in Example 1, except that a separator having a titanium content of 100% and having a serpentine-shaped flow path (1 mm wide x 1 mm deep) formed thereon was used instead of the first and second separators of Example 1, and that a titanium mesh layer was not included.

[0086]

[0087] Comparative Example 2

[0088] A membrane electrode assembly was manufactured in the same manner as in Example 1. Thereafter, a water electrolysis cell was assembled in the same manner as in Example 1, except that a separator having a titanium content of 100% and having a serpentine-shaped channel (1 mm wide x 1 mm deep) was used instead of the first separator of Example 1.

[0089]

[0090] Comparative Example 3

[0091] A membrane electrode assembly was manufactured in the same manner as in Example 1. Thereafter, a titanium mesh layer was laminated on the gas diffusion layer, and a water electrolysis cell was assembled in the same manner as in Example 1, except that the titanium mesh layer was laminated.

[0092]

[0093] Comparative Example 4

[0094] A membrane electrode assembly was manufactured in the same manner as in Example 1. Thereafter, a water electrolysis cell was assembled in the same manner as in Example 1, except that first and second separators (having a 100% titanium content) were replaced with first and second separators having a 100% stainless steel (SUS316L) content.

[0095]

[0096] Comparative Example 5

[0097] A membrane electrode assembly was manufactured in the same manner as in Example 1. Thereafter, a water electrolysis cell was assembled in the same manner as in Example 1, except that the titanium mesh layer was not included.

[0098]

[0099] Comparative Example 6

[0100] A membrane electrode assembly was manufactured in the same manner as in Example 1. Thereafter, a water electrolysis cell was assembled in the same manner as in Example 1, except that the titanium mesh layer was not included and a porous diffusion layer having a thickness of 450 μm was used instead of a porous diffusion layer having a thickness of 250 μm.

[0101]

[0102] Experimental example

[0103] For the electrolysis cells according to the above examples and comparative examples, cell performance measurements were performed. Specifically, 100 cm 2 By fabricating a unit cell, the flow rate is 2.5 (mL / min) / cm 2 , 0.3 A / cm with HCP-803 Potentiostat equipment from biologic at operating temperature 70 ℃. 2 30 minutes 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 by LSV (Linear Sweep Voltammetry). The measured results are shown in Table 1 and Fig. 3 below. The X-axis of Fig. 3 below represents current density, and the Y-axis represents cell voltage.

[0104]

[0105] Electrolysis cell performance (>1.9A@1.9V or higher) Euro processing example 12.13 AOK example 22.09 AOK comparison example 11.99 ANG comparison example 21.99 ANG comparison example 31.44 AOK comparison example 41.87 AOK comparison example 50.69 AOK comparison example 60.99 AOK

[0106] Referring to Table 1 and FIG. 3, Example 1, which is composed of a water electrolysis cell structure according to the present invention, can reduce the cost and process of separator processing according to the formation of a channel by having a titanium mesh layer serve as a channel on the anode side and a gas diffusion layer serve as a channel on the cathode side without forming a separate channel, and it can be confirmed that it has excellent cell performance with a current value exceeding 1.9 A according to a 1.9 V voltage condition.

[0107] In addition, Example 2 uses a clad metal having a titanium content of 20% and a stainless steel content of 80% instead of the separator of Example 1, and referring to Table 1, it can be confirmed that it has excellent cell performance without forming a separate flow path by satisfying the conditions and cell structure of the separator of the present invention.

[0108] On the other hand, Comparative Example 1 used a conventional separator having serpentine-shaped channels formed on both the anode and cathode, while Comparative Example 2 used the conventional separator only on the cathode side. Both Comparative Examples 1 and 2 require separate channel formation, which consumes excessive costs and detailed manufacturing processes, making it difficult to solve the problems of the present invention and the problems of conventional separators and electrolysis cells, and furthermore, it can be confirmed that the cell performance is inferior to that of Examples 1 and 2.

[0109] In addition, Comparative Example 3 has a titanium mesh layer applied to not only the anode side but also the cathode side, and it can be confirmed that it has inferior cell performance compared to the examples as it does not correspond to the cell structure of the present invention.

[0110] In addition, Comparative Example 4 used a separator made only of stainless steel material, and the cell performance deteriorated due to oxidation caused by the corrosive environment on the anode side, and oxidation progressed during long-term operation, and the cell performance gradually deteriorated.

[0111] In addition, Comparative Example 5 does not include a titanium mesh layer, and Comparative Example 6 has a porous diffusion layer whose thickness is outside the scope of the present invention. In each case, the porous diffusion layer served as a flow path instead of the titanium mesh layer, but it can be confirmed that the cell performance is inferior to that of the examples.

[0112] 100: First separator

[0113] 200: Second Separator

[0114] 300: Cathode

[0115] 400: Anode

[0116] 500: Membrane

[0117] 600: Gas diffusion layer

[0118] 700: Porous diffusion layer

[0119] 800: Titanium mesh layer

[0120] 900: Gasket

[0121] 10: First layer (titanium)

[0122] 20: Second layer (stainless steel)

Claims

1. A separator including a first separator and a second separator; A membrane electrode assembly comprising an anode, a separator, and a cathode disposed between the first separator and the second separator; A gas diffusion layer disposed between the cathode and the first separator; A porous diffusion layer disposed between the anode and the second separator; and a titanium mesh layer, The above separator comprises titanium, A water electrolysis cell that does not include a titanium mesh layer between the cathode and the first separator.

2. In claim 1, A water electrolysis cell in which the titanium mesh layer is arranged in contact with one surface of the second separator.

3. In claim 1, An electrolysis cell wherein the separator further comprises stainless steel, and the separator is a clad separator comprising titanium and stainless steel.

4. In claim 3, A water electrolysis cell, wherein the clad separator 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.

5. In claim 1, A water electrolysis cell wherein the above separator further comprises engineering plastic.

6. In claim 5, A water electrolysis cell 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.

7. In claim 1, The above separator is an electrolysis cell that does not include a euro.

8. In claim 1, A water electrolysis cell wherein the thickness of the above separator is 0.1 mm or more and 5.0 mm or less.

9. In claim 1, A water electrolysis cell wherein the thickness of the titanium mesh layer is 0.2 mm or more and 1 mm or less.

10. In claim 1, A water electrolysis cell wherein the thickness of the porous diffusion layer is 200 ㎛ or more and less than 450 ㎛.

11. In claim 1, A water electrolysis cell wherein the porous diffusion layer comprises titanium felt.

12. In claim 1, A water electrolysis cell wherein the thickness of the gas diffusion layer is 150 ㎛ or more and 400 ㎛ or less.

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

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