Separator plate and electrolysis apparatus including same

Abstract

The present invention relates to a separator plate comprising: a clad metal plate including a titanium layer and a stainless steel layer bonded to one surface of the titanium layer; and a titanium porous diffusion layer disposed on the other surface of the titanium layer, wherein the stainless steel layer includes a flow path to reduce the difficulty of flow path machining, and reduces the thickness of the separator plate to reduce electrical resistance, thereby improving electrolysis efficiency.

Description

Separator plate and electrolysis device including same

[0001] The present invention relates to a separator and an electrolytic device including the same.

[0002]

[0003] Carbon dioxide is a greenhouse gas that causes global warming and must be reduced. Known methods for reducing carbon dioxide include capture, chemical conversion, and electrochemical conversion. Among these, electrochemical conversion allows for precise control of the composition of other synthetic gases, offering greater economic benefits than simply removing carbon dioxide. Furthermore, electrolysis of carbon dioxide with water can yield carbon monoxide, ethylene, methane, formic acid, formate, various hydrocarbons, and organic compounds such as aldehydes and alcohols.

[0004] The electrochemical decomposition or reduction of carbon dioxide is categorized by ion exchange method. When using a cation exchange membrane, water is supplied to the anode and an electric current is applied. This causes the water to decompose at the anode, generating oxygen, electrons, and hydrogen ions. These hydrogen ions then migrate to the cathode through the cation exchange membrane. At the cathode, carbon dioxide reacts with the electrons generated at the anode and the hydrogen ions that have passed through the cation exchange membrane, resulting in a reduction reaction and conversion into another substance.

[0005] In addition, when using an anion exchange membrane, the activity of the electrochemical reaction improves in a strongly alkaline atmosphere, so a KOH aqueous solution of a certain concentration is generally used as the electrolyte. When carbon dioxide and water are supplied together to the cathode and current is applied, hydroxide ions (OH -) occurs, and the hydroxide ions move to the anode through the anion exchange membrane. The moved hydroxide ions are converted into water and oxygen at the anode, and electrons are generated in this process. The electrons move to the cathode along the conductor, and the moved electrons react with carbon dioxide and water at the cathode and decompose into carbon monoxide and hydroxide ions.

[0006] Through the above process, the electrochemical decomposition reaction of carbon dioxide is completed. At this time, the water supplied together with the carbon dioxide reacts with the electrons transferred separately from the carbon monoxide production reaction, undergoing electrolysis to produce hydroxide ions and simultaneously generate hydrogen gas. This reaction between water and electrons can be said to be a competitive reaction with the carbon monoxide production reaction. Since the above reactions are electrochemical reactions, the amount of carbon monoxide produced and the hydrogen / carbon dioxide ratio can be easily controlled by adjusting the voltage.

[0007] Meanwhile, a carbon dioxide electrolysis device is manufactured by stacking unit cells, which requires a bipolar plate having a bipolar surface placed between multiple membrane electrode assemblies. Conventional bipolar plates have different flow path shapes on each bipolar surface depending on the purpose, making the processing process complex and making it difficult to select a material that satisfies this processability. In addition, the surface of the bipolar plate facing the anode is made of titanium due to the corrosive environment. In this case, the surface may warp or deteriorate due to heat during the bipolar plate processing, making the use of a thick bipolar plate unavoidable. However, there was a problem that setting the thickness of the bipolar plate too thick increased the electrical resistance, which lowered the electrolysis efficiency.

[0008] (Patent Document 1) KR 2022-0079553 A

[0009]

[0010] The problem to be solved by the present invention is to provide a separator and an electrolysis device including the same, which can reduce the thickness and thereby reduce electrical resistance, reduce the difficulty of processing the flow path, and increase electrolysis efficiency by including a clad metal including a titanium layer and a stainless steel layer and a titanium porous diffusion layer on the surface of the titanium layer.

[0011]

[0012] The present invention provides a separator and an electrolytic device including the same.

[0013] (1) The present invention provides a separator comprising a clad metal plate including a titanium layer and a stainless steel layer bonded to one surface of the titanium layer, and a titanium porous diffusion layer disposed on the other surface of the titanium layer, wherein the stainless steel layer includes a flow path.

[0014] (2) The present invention provides a separator according to (1), wherein the titanium porous diffusion layer is made of titanium felt.

[0015] (3) The present invention provides a separator in (1) or (2) above, wherein the clad metal plate is formed by integrally forming the titanium layer and the stainless steel layer through forced rolling.

[0016] (4) The present invention provides a separator in which the thickness of the clad metal plate is 0.5 mm or more and 1.5 mm or less in any one of the above (1) to (3).

[0017] (5) The present invention provides a separator in which the ratio of the thickness of the titanium layer and the thickness of the stainless steel layer is 1:5 to 20 in any one of the above (1) to (4).

[0018] (6) The present invention provides a separator in which the thickness of the titanium porous diffusion layer is 0.6 mm or more and 0.8 mm or less in any one of the above (1) to (5).

[0019] (7) The present invention provides a separator according to any one of the above (1) to (6), wherein the titanium layer and the titanium porous diffusion layer do not include a flow path.

[0020] (8) In any one of the above (1) to (7), the area of ​​the separator is 100 cm 2 Above 5000 cm 2 A separator is provided as follows.

[0021] (9) The present invention provides an electrolysis device comprising a membrane electrode assembly in which an anode, a separator, a cathode, and a gas diffusion layer are arranged in order, a separator according to any one of (1) to (8) arranged between a plurality of the membrane electrode assemblies, a first gasket arranged between the anode and the separator, and a second gasket arranged between the cathode and the separator, wherein the thickness of the first gasket is thicker than the thickness of the second gasket.

[0022] (10) The present invention provides an electrolysis device in which, in the above (9), the ratio of the thickness of the first gasket and the thickness of the second gasket is 1:0.2 to 0.3.

[0023] (11) The present invention provides an electrolysis device according to (9) or (10), wherein the membrane electrode complex further includes a porous layer on one side of the anode where the separator is not disposed.

[0024] (12) The present invention provides an electrolysis device in which, in the above (11), the first gasket is arranged to surround the side surfaces of the porous layer and the titanium porous diffusion layer, and the second gasket is arranged to surround the side surfaces of the gas diffusion layer.

[0025] (13) The present invention provides an electrolytic device in any one of the above (10) to (12), wherein the electrolytic device electrolyzes carbon dioxide to produce at least one substance selected from the group consisting of carbon monoxide, ethylene, methane, formic acid, hydrocarbons, aldehydes, and alcohols.

[0026]

[0027] According to the separator of the present invention, by securing a current collection area and a flow path cross-sectional area while reducing the thickness of the separator and thereby reducing electrical resistance, the electrolysis efficiency can be improved when the separator is applied to an electrolysis device.

[0028] In addition, according to the separator of the present invention, since a separate path is not formed on the surface facing the cathode, the complexity of path processing can be reduced, and at the same time, material and processing costs can be reduced.

[0029] In addition, according to the electrolysis device of the present invention, by applying gaskets of different thicknesses, the gap between the separator and the membrane electrode assembly can be reduced, thereby reducing electrical resistance and improving electrolysis efficiency.

[0030]

[0031] Figure 1 is a side view of the separator plate of the present invention.

[0032] Figure 2 is a graph showing the resistance measured in Example 1 and Comparative Example 1.

[0033] Figure 3 is a table showing the results of measuring the carbon monoxide Faraday efficiency, hydrogen Faraday efficiency, carbon dioxide conversion rate, and overvoltage of Example 1 and Comparative Example 2.

[0034] Figure 4 is a side view of a separator plate of the present invention including a gasket.

[0035]

[0036] 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.

[0037] 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.

[0038] 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.

[0039]

[0040] separator

[0041] The present invention provides a separator comprising a clad metal plate (10) including a titanium layer (11) and a stainless steel layer (13) bonded to one surface of the titanium layer (11), and a titanium porous diffusion layer (50) disposed on the other surface of the titanium layer (11), wherein the stainless steel layer includes a flow path.

[0042] The separator included in the carbon dioxide electrolysis device of the present invention not only serves to supply or separate the reaction gas, but also serves to physically support the membrane electrode assembly (30) and the gas diffusion layer when the cell is connected, and further serves to discharge products and manage heat inside the cell through electrical conduction and electrochemical reaction.

[0043] The separator included in a conventional electrochemical conversion device is manufactured by individually laminating separate metal plates formed with a flow path. For example, a metal plate formed with a cathode flow path and a metal plate formed with an anode flow path may be laminated in that order, and in some cases, a separator may be additionally placed between the metal plates. In this case, the lamination of the metal plates may be performed using methods such as laser welding, brazing, resistance spot welding, or adhesive bonding. However, since these methods manufacture the separator through a separate bonding process for each metal plate, they have the problem of high complexity in the manufacturing process, increased cost, and increased time required. Furthermore, when individual metal plates are simply laminated in this way, the electrical resistance increases at the laminated interface, which has the problem of reducing the efficiency of the electrochemical conversion device. Furthermore, since the overall thickness of the separator increases during lamination, this can also cause an increase in electrical resistance.

[0044] In order to solve the above problem, the separator of the present invention includes a clad metal plate (10). Specifically, the clad metal plate (10) may be formed integrally by the titanium layer (11) and the stainless steel layer (13) through forced rolling. The clad metal plate (10) 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 in which the 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 (10) of the present invention corresponds to a different material from a conventional separator in which two metal plates are simply bonded or laminated by using adhesive or welding, etc., and the clad metal plate (10) 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 metal plates are laminated. In addition, since each of the above layers is hetero-bonded, an electrolysis cell can be configured with only one separator even in different environments of the two poles (cathode and anode), thereby reducing the interfacial resistance between the materials of the electrical conversion device, thereby improving the efficiency during electrical conversion.

[0045] The above clad metal includes a titanium layer (11) and a stainless steel layer (13), and the titanium layer (11) can face the anode layer when mounted in an electrolysis device, and the stainless steel layer (13) can face the cathode layer. Since hydroxide ions in the anode layer generate water and oxygen and correspond to a moisture environment, titanium, which is resistant to corrosion, is preferred.

[0046] According to one embodiment of the present invention, the titanium porous diffusion layer (50) may be titanium felt, and the titanium layer (11) and the titanium porous diffusion layer (50) may not include a flow path.

[0047] Conventional separators used in electrochemical conversion devices such as electrolysis and fuel cells may include multiple channels on the surface facing the anode and the surface facing the cathode, respectively, and the channels can transport various fluids, including carbon dioxide, to diffuse reactants into the catalyst layer. Furthermore, the oxygen evolution reaction of the anode and the carbon dioxide reduction 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 single plate. 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 plate thickness. Furthermore, due to the processing characteristics of 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 plates, causing the plates 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.

[0048] Accordingly, the present invention solves the above problem by positioning a titanium porous diffusion layer (50) without forming a separate channel in the titanium layer (11) in order to maintain smooth transport of materials and reduce electrical resistance while maintaining a thin thickness of the separator. The titanium porous diffusion layer (50) may be titanium felt, and the titanium porous diffusion layer (50) can improve the contact force between the separator and the membrane electrode assembly (30) when the electrolysis device is fastened, and can absorb processing errors that occur during processing of the electrolysis device by reducing the gap. In addition, it can serve as a channel for the anode and at the same time, make good contact with the catalyst layer to reduce battery resistance and overvoltage. In addition, since a separate channel is not formed in the titanium layer, the cost and processing time associated with the channel formation process can be reduced.

[0049] In addition, the separator of the present invention has a porous diffusion layer positioned on the titanium layer without a separate channel, but the stainless steel layer (13) includes a channel on a surface that is not bonded with the titanium layer (11). The channel included in the stainless steel layer (13) faces the cathode and may have a serpentine or interdigitated type structure. The channel of the structure has a rotating section so that the flow rate of the transported fluid increases, thereby facilitating the discharge of products and uniformly distributing the fluid, thereby allowing a greater amount of reactants to react with the catalyst layer. If a channel is not formed in the stainless steel layer, the mass transfer resistance may increase, which may lead to local carbon dioxide depletion. In addition, since the stainless steel layer includes a separate channel, the supplied carbon dioxide may be evenly distributed over the entire active area.

[0050] According to one embodiment of the present invention, the thickness of the clad metal plate (10) may be 0.5 mm or more and 1.5 mm or less. For example, the thickness of the clad metal plate (10) is 0.50 mm or more, 0.52 mm or more, 0.55 mm or more, 0.57 mm or more, 0.59 mm or more, 0.60 mm or more, 0.63 mm or more, 0.65 mm or more, 0.67 mm or more, 0.69 mm or more, 0.70 mm or more, 1.5 mm or less, 1.45 mm or less, 1.4 mm or less, 1.35 mm or less, 1.3 mm or less, 1.25 mm or less, 1.2 mm or less, 1.15 mm or less, 1.1 mm or less, 1.05 mm or less, 1.0 mm or less, 0.97 mm or less, 0.95 mm or less, 0.93 mm or less, 0.90 mm or less, 0.87 mm or less, 0.85 mm or less, 0.83 mm or less, It may be 0.80 mm or less, 0.77 mm or less, 0.75 mm or less, 0.73 mm or less, or 0.71 mm or less. Specifically, the thickness of the clad metal plate (10) may be 0.6 mm or more and 0.8 mm or less, and when the thickness of the clad metal plate (10) satisfies the above range, it is possible to form a thin thickness while maintaining excellent durability and physical strength, so that the fastening property can be improved when manufacturing the electrolysis device, and accordingly, the interface resistance between the components within each of the devices can be reduced, thereby improving the electrolysis efficiency.

[0051] According to one embodiment of the present invention, the ratio of the thickness of the titanium layer (11) to the thickness of the stainless steel layer (13) may be 1:5 to 20. For example, the ratio of the thickness of the titanium layer (11) to the thickness of the stainless steel layer (13) may be 1:5 or more, 5.5 or more, 5.7 or more, 5.9 or more, 6 or more, 6.3 or more, 6.5 or more, 6.7 or more, 7.0 or more, 20 or less, 19.5 or less, 19 or less, 18.5 or less, 18 or less, 17.5 or less, 17 or less, 16.5 or less, 16 or less, 15.5 or less, or 15 or less. Specifically, the ratio may be 1:5 to 19, and when the ratio of the thickness of the titanium layer (11) and the thickness of the stainless steel layer (13) 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 to improve the electrolysis efficiency.

[0052] Specifically, the thickness of the titanium layer (11) may be 0.03 mm or more, 0.04 mm or more, 0.05 mm or more, 0.15 mm or less, 0.14 mm or less, 0.13 mm or less, 0.11 mm or less, 0.1 mm or less, 0.09 mm or less, 0.08 mm or less, 0.07 mm or less, 0.06 mm or less, and the thickness of the stainless steel layer (13) may be 0.5 mm or more, 0.51 mm or more, 0.53 mm or more, 0.55 mm or more, 0.57 mm or more, 0.59 mm or more, 1.45 mm or less, 1.4 mm or less, 1.35 mm or less, 1.3 mm or less, 1.25 mm or less, 1.2 mm or less, 1.15 mm or less, 1.1 mm or less, 1.05 mm or less, 1.0 mm or less, It can be 0.95 mm or less, 0.9 mm or less, 0.85 mm or less, 0.8 mm or less, 0.75 mm or less, 0.7 mm or less, 0.65 mm or less, or 0.6 mm or less. The separator of the present invention can maintain excellent physical durability and strength while reducing costs and improving resistance characteristics by controlling the thickness of the titanium layer (11) and the stainless steel layer (13) within the range with the thickness ratio of the titanium layer (11) and the stainless steel layer (13) described above.

[0053] According to one embodiment of the present invention, the thickness of the titanium porous diffusion layer (50) may be 0.6 mm or more and 0.8 mm or less. For example, the thickness of the titanium porous diffusion layer (50) may be 0.6 mm or more, 0.62 mm or more, 0.64 mm or more, 0.65 mm or more, 0.67 mm or more, 0.69 mm or more, 0.7 mm or more, 0.8 mm or less, 0.78 mm or less, 0.75 mm or less, 0.73 mm or less, or 0.72 mm or less. Specifically, the thickness may be 0.6 mm or more and 0.7 mm or less, and when the thickness of the titanium porous diffusion layer (50) satisfies the above range, it can perform the role of a flow path without forming a separate flow path in the titanium layer (11), and oxygen generated by the reaction can be effectively discharged through an optimal space area, so that overvoltage can be reduced. In addition, since titanium has excellent strength, the machining and etching work for forming a flow path in the titanium layer (11) of the separator is difficult and requires cost and time, but when the titanium porous diffusion layer (50) having the above thickness is brought into contact with the titanium layer (11), 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.

[0054] 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 2 Ideal, 2000 cm 2Above, 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:

[0055] 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 carbon dioxide or water 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 separator applied also increases, and when such a large-area separator is manufactured by laminating separate metal plates, 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 forming the flow path, and a peeling phenomenon may occur due to long-term storage.

[0056] On the other hand, the separator of the present invention uses a clad metal plate (10) including a titanium layer (11) and a stainless steel layer (13), and includes a titanium porous diffusion layer (50) on the surface of the titanium layer (11), thereby making it easy to manufacture a large-area separator, preventing physical durability and peeling when left for a long period of time, and reducing interfacial resistance through a thin thickness.

[0057]

[0058] electrolysis device

[0059] The present invention provides an electrolysis device comprising a membrane electrode assembly (30) in which an anode, a separator, a cathode, and a gas diffusion layer (20) are sequentially arranged, a separator according to the present invention arranged between a plurality of the membrane electrode assemblies, a first gasket (61) arranged between the anode and the separator, and a second gasket (63) arranged between the cathode and the separator, wherein the thickness of the first gasket (61) is thicker than the thickness of the second gasket (63). In addition, the membrane electrode assembly may further include a porous layer on one surface of the anode on which the separator is not arranged.

[0060] According to one embodiment of the present invention, the first gasket (61) may be arranged to surround the side surfaces of the porous layer and the titanium porous diffusion layer (50), and the second gasket (63) may be arranged to surround the side surfaces of the gas diffusion layer. Specifically, the first gasket (61) may be positioned on the anode side, and the second gasket (63) may be positioned on the cathode side.

[0061] The above gasket can prevent reactants or products from flowing out of the device through a corresponding path or from mixing within the device through different paths when the electrolysis device including the above separator is operated. In other words, the gasket can serve to prevent reactants or products from flowing into areas other than the designated path.

[0062] 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.

[0063] The separator included in the carbon dioxide electrolysis device of the present invention may include a gasket in a line shape rather than a surface shape to address the conventional problems. The gasket of the present invention may be formed in a structure that surrounds and separates the area including the flow path, and a plurality of line-shaped gaskets may be formed in two or three or more layers.

[0064] According to one embodiment of the present invention, the thickness ratio of the first gasket (61) and the thickness of the second gasket (63) may be 1: 0.2 to 0.3. For example, the thickness ratio of the first gasket (61) and the second gasket (63) may be 1: 0.2 or more, 0.21 or more, 0.22 or more, 0.23 or more, 0.24 or more, 0.3 or less, 0.29 or less, 0.28 or less, 0.27 or less, 0.26 or less, or 0.25 or less. Specifically, the thickness ratio may be 1: 0.25 or more and 0.3 or less. When the above thickness is satisfied, the gap between the gasket, the separator, the porous layer, the titanium porous diffusion layer (50), and the gas diffusion layer can be reduced, and leakage of internal substances to the outside can be effectively prevented. For example, the first gasket (61) may be 1.0 mm or more, 1.1 mm or more, 1.2 mm or more, 1.3 mm or more, 1.35 mm or more, 1.5 mm or less, 1.45 mm or less, or 1.4 mm or less, and the second gasket (63) may be 0.2 mm or more, 0.25 mm or more, 0.3 mm or more, 0.35 mm or more, 0.4 mm or more, 0.6 mm or less, 0.55 mm or less, 0.5 mm or less, or 0.45 mm or less.

[0065] The above separator may be arranged on at least one side of the membrane electrode assembly, and specifically, may be included between the membrane electrode assemblies. In addition, a membrane electrode assembly including a separator between an anode and a cathode may form an electrolysis unit cell by closely arranging the separator on one or both sides of the membrane electrode assembly.

[0066] 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 fuel cells and water electrolysis, and devices capable of reducing and converting carbon dioxide and NOx. Specifically, the electrolysis cell can be included in an electrolysis device that converts carbon dioxide into carbon monoxide and ethylene.

[0067] 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, oxidizing 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, allowing reactants introduced to the cathode to react with electrons and hydrogen ions transferred from the anode to generate products. 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 may provide a path for ions to move between the anode and the cathode and serve to isolate physical contact between the anode and the cathode.

[0068] In addition, the anode and the cathode of the membrane electrode assembly of the carbon dioxide electrolysis device of the present invention may each include a catalyst layer. In addition, water vapor supplied together with carbon dioxide in the cathode region generates a reduction product through an electroreduction reaction on the cathode surface. Therefore, the cathode may include a gas diffusion layer (20) to evenly supply humidified carbon dioxide gas to the cathode region. When the cathode includes a hydrophobic gas diffusion layer (20), the supplied carbon dioxide can be smoothly diffused, distributed, and supplied to the catalyst layer of the cathode. In addition, the hydrophobic gas diffusion layer (20) effectively prevents moisture condensation, thereby ensuring that the supply of carbon dioxide is continuously and uniformly conducted and at the same time, enabling the electrolysis reaction to proceed smoothly. In addition, the catalyst layer may have a surface such as a porous structure so that gas permeability characteristics are well exhibited on the surface.

[0069] According to one embodiment of the present invention, the anode 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, such as Ta2O5, IrO2, for an oxygen evolution reaction. Specifically, the anode in the carbon dioxide electrolysis device of the present invention may include titanium (Ti) coated with iridium oxide (IrO2). The titanium may be a porous layer, and may include a titanium mesh (40) or titanium paper. When the titanium mesh (40) or paper is used, diffusion of a material may be smoothly achieved. Meanwhile, the titanium mesh or paper may include a plurality of pores, and the porosity of the titanium mesh (40) or paper may be about 50 to 80%. The titanium mesh (40) or paper may have a thickness of 60 to 500 μm. If the thickness is less than 60 μm, the pores of the titanium mesh (40) or paper may become clogged after the pressing process, which may result in a decrease in performance. If the thickness exceeds 500 μm, the mass transfer path of water may become longer, which may result in a decrease in performance.

[0070] In addition, since the carbon dioxide reduction reaction occurring at the cathode competes with the hydrogen evolution reaction, a catalyst that requires a high voltage for the hydrogen evolution reaction and is active in the carbon dioxide reduction reaction may be included. The catalyst layer of the cathode may include at least one selected from the group consisting of Sn, a Sn alloy, Al, Au, Ag, C, Cd, Co, Cr, Cu, a Cu alloy, Ga, Hg, In, Mo, Nb, Ni, NiCo2O4, a Ni alloy, a Ni-Fe alloy, Pb, Rh, Ti, V, W, Zn, and mixtures thereof for the hydrogen evolution reaction. Specifically, the cathode in the carbon dioxide electrolysis device of the present invention may include silver (Ag).

[0071] In addition, the separation membrane may include a cation exchange membrane (CEM) or an anion exchange membrane (AEM). Specifically, the cation exchange membrane may act as a bonding membrane that prevents a reducing substance generated at the cathode through catalytic action from moving to the anode and being oxidized, and may act as a separation phase that inhibits the permeation of anions and allows cations such as hydrogen ions (H+) to pass through.

[0072] Additionally, water is oxidized at the anode to produce hydrogen ions (H + ) occurs, and the problem of reducing the conversion rate of carbon dioxide by saturating the active site of the catalyst where the hydrogen ions are transferred to the cathode in excess may occur. In this case, the anion exchange membrane can reduce the amount of the hydrogen ions transferred to the cathode. The anion exchange membrane can prevent the carbon dioxide conversion performance of the cathode from being impaired by blocking the movement of hydrogen ions, and OH - , HCO3 - , CO3 2- Anions such as these can act as a permeable separation phase.

[0073] In addition, the gas diffusion layer (20) may be a porous body using a carbon material such as carbon fiber cloth, carbon fiber felt, or carbon fiber paper, or a metal porous body made of a thin metal plate with a mesh structure such as expanded metal or metal mesh, and in the carbon dioxide electrolysis cell of the present invention, the gas diffusion layer (20) may be a carbon fiber cloth.

[0074] According to one embodiment of the present invention, the electrolysis device may electrolyze carbon dioxide to produce one or more substances selected from the group consisting of carbon monoxide, ethylene, methane, formic acid, hydrocarbons, aldehydes, and alcohols.

[0075]

[0076] 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.

[0077]

[0078] <Example 1>

[0079] The carbon dioxide electrolysis unit cell was operated under the operating conditions described below.

[0080] - Reaction current density: 200 mA / cm 2 (Constant current operation)

[0081] - Reaction voltage: 1~4 V

[0082] - Reaction temperature: 40 ℃

[0083] - Reaction pressure: 1 atm (atmospheric pressure)

[0084] - Anode catalyst: IrO2on Ti mesh

[0085] - Cathode catalyst: Ag powder

[0086] - Membrane: Porous membrane (PES, Polyehtersulfone)

[0087] - Electrode area: 100 cm 2

[0088] - Gas diffusion layer: Sigracet 39BB

[0089] - Anode electrolyte: 0.25 M Cs2CO3 (200 ml / min)

[0090] - Cathode reactant: 40 ℃ Humidified CO2 gas (200 ccm)

[0091] - Separator material: Clad metal (thickness: 0.6 mm) and titanium felt (thickness: 0.6 mm) made of titanium (Ti) (thickness: 0.05 mm) and stainless steel (STS) (thickness: 0.55 mm)

[0092] - Separator (stainless steel metal layer) Euro structure: serpentine shape

[0093] - Separator (titanium metal layer) Euro structure: No euro

[0094]

[0095] <Comparative Example 1>

[0096] A carbon dioxide electrolysis unit cell was operated under the same conditions as in Example 1, except that a multilayer separator manufactured by laminating titanium (Ti) metal plates (thickness: 0.05 mm) and stainless steel (TST) metal plates (thickness: 0.55 mm), each having a serpentine-shaped flow path formed through machining, was used instead of the separator of Example 1.

[0097]

[0098] <Comparative Example 2>

[0099] A carbon dioxide electrolysis unit cell was operated under the same conditions as in Example 1 using a separator made of the same clad metal material as in Example 1, except that neither the stainless steel metal layer nor the titanium metal layer included a euro structure.

[0100]

[0101] Experimental Example 1

[0102] The products resulting from the carbon dioxide reduction reaction were analyzed using gas chromatography using the carbon dioxide electrolysis unit cell according to the above examples and comparative examples. At this time, the impedance (resistance), faradaic efficiency of carbon monoxide, and overvoltage were measured according to the following measurement methods.

[0103] Data comparing the impedance (resistance) of Example 1 and Comparative Example 1 are shown in Fig. 1, and data comparing the carbon monoxide Faraday efficiency and overvoltage of Examples 1 and 2 and Comparative Examples 2 and 3 are shown in Fig. 2.

[0104]

[0105] (1) Carbon monoxide Faraday efficiency (CO Faraday efficiency, %)

[0106] The composition of the gas discharged from the carbon dioxide electrolysis unit cell was measured through GC (Gas-Chromatography) analysis. In addition, the Faraday efficiency was calculated using the following equation.

[0107] [Mathematical Formula 1]

[0108]

[0109] In the above mathematical expression 1, Q is the flow rate in the path that discharges the product outside the carbon dioxide electrolysis unit cell, F is the Faraday constant, p is the pressure, T is the measured temperature, and R is the ideal gas constant. The total current (i total ) is the value of the total current applied over time, and the current for the product (i product) is the volume of gas measured through GC analysis (V product ) is the value calculated from.

[0110]

[0111] (2) Impedance (mΩ)

[0112] Ohmic resistance was measured at 0.2 V and frequencies of 100 KHz-10 Hz using a VSP potentiostat from BioLogic.

[0113]

[0114] (3) Voltage (V)

[0115] Current application and voltage measurement were performed using a VSP potentiostat from BioLogic. An 80 A booster was installed to apply current corresponding to a large area. The current application was 200 mA / cm 2 After maintaining it for a certain period of time, the voltage was recorded at the point where 30 minutes had elapsed. At this time, GC (Gas-Chromatography) analysis was also performed simultaneously.

[0116]

[0117] FIG. 2 shows the measured impedance values ​​of Example 1 and Comparative Example 1. As a result of the experiment, Example 1, which was used as a separator including a clad metal plate, showed a resistance of about 2.85 mΩ, and Comparative Example 1, which was used as a separator by laminating two types of conventional metal plates, was measured to have a resistance of about 6.10 mΩ. Through the above results, it can be confirmed that the clad metal plate corresponding to one material through heterojunction has superior characteristics in terms of resistance compared to the separator formed by simply laminating two types of metal plates. In addition, if this corresponds to a device in which cells are stacked rather than unit cells, the voltage increase due to resistance will overlap, and it is predicted that there will be a significant difference between Example 1 and Comparative Example 1 in terms of electrolysis efficiency due to an increase in overvoltage in the device and system.

[0118]

[0119] Experimental Example 2

[0120] For the electrolysis devices of the above Example 1 and Comparative Example 2, each electrode area is 1,000 cm 2 , carbon dioxide supply flow rate is 6 LPM and 8 LPM, current density is 200 mA / cm 2 In addition to the conditions, 300 mA / cm 2 Under the conditions, the carbon dioxide conversion rate, carbon monoxide Faraday efficiency, hydrogen Faraday efficiency, and overvoltage were measured. The carbon dioxide conversion rate (%) was calculated as the ratio of carbon monoxide (CO) produced to the amount of carbon dioxide (CO2) gas injected per hour. In addition, the carbon monoxide Faraday efficiency and overvoltage were measured in the same manner as in Experimental Example 1, and the hydrogen Faraday efficiency was measured in the same manner as the carbon monoxide Faraday efficiency. The measurement results are shown in Figure 3 below.

[0121] Fig. 3 is a table showing the results of measuring the carbon monoxide Faraday efficiency, hydrogen Faraday efficiency, carbon dioxide conversion rate, and overvoltage of Example 1 and Comparative Example 2. Referring to Fig. 3, it can be confirmed that Example 1, which includes a channel in the stainless steel layer among the clad metal plates, shows superior levels in all characteristics compared to Comparative Example 2, which uses the clad metal plate itself without any channel. This is because, when there is no channel structure in the stainless steel layer, the resistance to mass transfer increases, causing local carbon dioxide depletion, and thereby decreasing the carbon monoxide Faraday efficiency and carbon dioxide conversion rate, and increasing the hydrogen Faraday efficiency and overvoltage.

[0122]

[0123] 10: Clad metal plate

[0124] 11: Titanium layer

[0125] 13: Stainless steel layer

[0126] 20: Gas diffusion layer

[0127] 30: Membrane electrode assembly

[0128] 40: Titanium mesh

[0129] 50: Titanium porous diffusion layer

[0130] 61: First gasket

[0131] 63: Second gasket

Claims

1. A clad metal plate comprising a titanium layer and a stainless steel layer bonded to one surface of the titanium layer; and Comprising a titanium porous diffusion layer arranged on the other surface of the titanium layer, A separator plate comprising the stainless steel layer above.

2. In claim 1, A separator wherein the above titanium porous diffusion layer is made of titanium felt.

3. In claim 1, The above clad metal plate is a separator plate in which the titanium layer and the stainless steel layer are integrally formed by forced rolling.

4. In claim 1, A separator wherein the thickness of the clad metal plate is 0.5 mm or more and 1.5 mm or less.

5. In claim 1, A separator wherein the ratio of the thickness of the titanium layer to the thickness of the stainless steel layer is 1:5 to 20.

6. In claim 1, A separator having a thickness of the titanium porous diffusion layer of 0.6 mm or more and 0.8 mm or less.

7. In claim 1, A separator wherein the titanium layer and the titanium porous diffusion layer do not include a euro.

8. In claim 1, The area of the above separator is 100 cm 2 Above 5000 cm 2 A separator having the following:

9. A membrane electrode assembly in which an anode, a separator, a cathode, and a gas diffusion layer are arranged in sequence; A separator according to claim 1 disposed between a plurality of said membrane electrode assemblies; a first gasket disposed between the anode and the separator; and Including a second gasket disposed between the cathode and the separator, An electrolytic device wherein the thickness of the first gasket is thicker than the thickness of the second gasket.

10. In claim 9, An electrolytic device, wherein the ratio of the thickness of the first gasket and the thickness of the second gasket is 1:0.2 to 0.

3.

11. In claim 9, An electrolytic device wherein the membrane electrode complex further includes a porous layer on one side of the anode where the separator is not disposed.

12. In claim 11, The above first gasket is arranged to surround the side of the porous layer and the titanium porous diffusion layer, An electrolysis device wherein the second gasket is arranged to surround a side of the gas diffusion layer.

13. In claim 9, The above electrolytic device is an electrolytic device that electrolyzes carbon dioxide to produce one or more substances selected from the group consisting of carbon monoxide, ethylene, methane, formic acid, hydrocarbons, aldehydes, and alcohols.

Images