KR20230023930A - Solid oxide fuel cell for ammonia fuel - Google Patents

Abstract

The present invention relates to a stack (electrode assembly) of solid oxide fuel cell using ammonia as fuel and a manufacturing method thereof, and more specifically, to a solid oxide fuel cell stack (electrode assembly) for ammonia fuel which improves the performance of a fuel cell by preventing deterioration of the solid oxide fuel cell which supplies ammonia as fuel in a high-temperature environment, and a solid oxide fuel cell for ammonia fuel including the same, and a manufacturing method thereof.

Description

Solid oxide fuel cell for ammonia fuel

The present invention relates to a solid oxide fuel cell for ammonia fuel, and specifically, to a solid oxide fuel cell stack using ammonia as fuel, a method for manufacturing the same, and a solid oxide fuel cell for ammonia fuel manufactured including the fuel cell stack More specifically, a solid oxide fuel cell stack that improves the performance of a fuel cell by preventing deterioration of a solid oxide fuel cell that supplies ammonia as fuel in a high-temperature environment, a manufacturing method thereof, and the fuel cell stack It relates to a solid oxide fuel cell for ammonia fuel manufactured by including.

Recently, interest in using renewable energy such as wind power and solar power has been highlighted in order to suppress the emission of greenhouse gases that cause global warming. However, renewable energy has a limited use area, so it is a system that generates electricity in areas with high energy efficiency such as sunlight, uses it to produce hydrogen or ammonia, and transports the hydrogen or ammonia as a hydrogen energy source. development is in progress.

In particular, ammonia is a compound composed of hydrogen and nitrogen, and has the advantage of not generating carbon-based polluting gas compared to the case of using hydrocarbon-based fuel. However, in order to use ammonia as hydrogen energy again, it must pass through a reactor that separates hydrogen in a high-temperature environment.

On the other hand, when ammonia is used as a fuel for a solid oxide fuel cell, which is a power generating device, there is an advantage in that it can be used as hydrogen energy without a high-temperature reactor as described above.

The solid oxide fuel cell for ammonia fuel is a device in which fuel and air are supplied to a stack in which a plurality of cells are stacked and electricity is generated through an electrochemical reaction between the two gases in a high-temperature environment. A stack of a solid oxide fuel cell includes a basic unit cell including an electrolyte and an electrode (anode and cathode); A metal separator ('metal separator') that electrically connects the unit cell and other unit cells and allows fuel and air to flow smoothly; A metal mesh for contact and buffering ('anode buffer metal mesh of cathode electrode', 'anode electrode buffer metal mesh') existing between the electrode and the metal separator and connecting the electrode and the metal separator; manifolder; sealing material; and an end plate; It is composed of parts such as (See Figure 1)

The components of this stack are metal materials, and the metal materials include ceramics, metals, alloys, and the like. Among the parts, in particular, the metal separator is made of an alloy of iron and chromium, the anode is made of nickel, and the anode buffer metal mesh of the anode electrode is made of nickel. When these metal materials such as nickel or iron are directly exposed to ammonia in a high-temperature environment, deterioration proceeds, which may lead to a decrease in fuel cell performance.

The main cause of deterioration leading to the reduction in fuel cell performance is a corrosion phenomenon when the metal material, such as iron or nickel, is directly exposed to ammonia for a long time in a high-temperature environment. This is because the movement of ions is blocked.

The decrease in performance of the fuel cell as described above causes a decrease in efficiency and stability of the fuel cell system.

Therefore, in order to expand the use of ammonia fuel fuel cells that utilize ammonia fuel in solid oxide fuel cells as a hydrogen transport medium, a technology to prevent deterioration of metal materials included in the stack that causes a decrease in fuel cell performance is required. .

KR 10-2068947 B1(2020.01.21. Announcement)

The present invention relates to a solid oxide fuel cell stack that solves the problem of preventing deterioration of the metal material of the stack, which causes a decrease in the performance of a solid oxide fuel cell that operates using ammonia as a direct fuel in a high-temperature environment, a method for manufacturing the same, and the fuel cell An object of the present invention is to provide a solid oxide fuel cell for ammonia fuel including a stack.

In order to achieve the above object of preventing deterioration of the metal material of the fuel cell stack component of the present invention, the present invention serves to ensure mechanically stable contact between the two contact surfaces of the anode and the metal separator. Provided is a solid oxide fuel cell stack for ammonia fuel including a metal mesh composite for buffering an anode electrode in which an ammonia decomposition catalyst is partially coated on an anode electrode buffering metal mesh.

By providing the fuel electrode buffer metal mesh composite coated with the ammonia decomposition catalyst as described above, the metal material parts of the fuel cell stack of the present invention i) an electrode (anode) of a unit cell in which an electrochemical reaction proceeds; ii) a metal separator electrically connecting the unit cells and allowing fuel and air to flow smoothly; and iii) components including a metal material such as an anode buffer metal mesh, which serves to ensure mechanically stable contact between the electrode (anode) and the two contact surfaces of the metal separator, are resistant to ammonia fuel at high temperature. deterioration is prevented, thereby improving the performance of the fuel cell.

The main cause of such deterioration is that the metal material of the parts is directly exposed to ammonia in a high-temperature environment, and a nitridation reaction such as nickel nitride (Ni ₃ N) or iron nitride (FeN) is formed on the surface of the metal material, so that electrons or ions because movement is blocked.

However, ammonia, the fuel of the fuel cell, is removed from the electrode (anode) side by the catalyst of the ammonia decomposition catalyst of the ammonia decomposition catalyst, which is a means for solving the problems of the present invention, of the anode buffer metal mesh composite. Before reaching the metal surface of a metal material component such as a metal separator or a metal separator, it is partially decomposed to generate hydrogen.

Accordingly, in the anode electrode where the electrochemical reaction for electricity generation occurs, the direct use of ammonia as a fuel is reduced, and instead, as hydrogen decomposed from the ammonia is used, a nitrification reaction (metal and nitrogen, NiN3, FeN, etc.) are suppressed, and thus durability can be greatly improved.

The ammonia decomposition catalyst coated on a portion of the anode buffer metal mesh of the present invention for exhibiting the above functions and effects is selected from the group consisting of metals such as Ni, Ru, Co, Fe, and Mo and ceramics having conductivity It may contain one or more substances that are.

Among the ammonia decomposition catalysts coated on a portion of the anode buffer metal mesh to prepare the anode buffer metal mesh composite, the metal may be a metal oxide according to a coating method; metal salts; Alternatively, metal powder or the like is used. Metal oxides as needed for coating; metal salts; Alternatively, it may be provided in the form of a liquid composite in the form of a metal solution or paste such as metal powder and coated.

Among the liquid composites for coating the anode buffer metal mesh, the coating of the anode buffer metal mesh using a metal solution is applied to a metal solution prepared by mixing a metal-containing material dissolved in a solvent, such as a metal salt or a metal oxide, with a solvent. By impregnating and drying the buffer metal mesh, it is possible to manufacture an anode buffer metal mesh composite having a microstructure in which metal is uniformly dispersed on the surface of the anode buffer metal mesh. The solvent is a solvent in which the metal salt, metal oxide, and the like are dissolved.

In addition, the metal powder or ceramic material having conductivity is combined with a conventional organic or inorganic vehicle in a powder form to form a paste and coated on the surface of the anode buffer metal mesh by a conventional screen printing method to obtain an anode buffer metal mesh composite. can be manufactured

In addition to the above methods, as a method for coating the surface of the anode buffer metal mesh with a catalytic material, electroplating or electroless plating, chemical vapor deposition (CVD), physical vapor deposition (sputtering), thermal spray coating, dip coating, screen printing, spin, if necessary Various methods such as coating may be used.

In addition, the coating thickness is characterized in that 2nm to 60㎛.

In addition, the coated portion of the anode buffer metal mesh may be 0.1 to 99.9% of the total area of the anode buffer metal mesh.

The present invention also provides a method of manufacturing the solid oxide fuel cell stack for ammonia fuel, and a solid oxide fuel cell for ammonia fuel manufactured including the stack.

The ammonia fuel-based solid oxide fuel cell of the present invention has an effect of having higher fuel cell durability and performance compared to conventional fuel cells even in a high-temperature ammonia supply environment.

That is, according to the present invention, the ammonia decomposition reaction due to the coated catalyst proceeds in the anode buffer metal mesh coated with the ammonia decomposition catalyst of the ammonia fuel-based solid oxide fuel cell, that is, the anode buffer metal mesh composite, thereby preventing ammonia decomposition. A separate ammonia reforming reactor device is not required, or the durability of the fuel cell cell is improved with a simple additional configuration, resulting in a simplified system.

In addition, as described above, hydrogen generated by the ammonia decomposition reaction due to the coated catalyst in the anode buffer metal mesh composite is directly used as a fuel of the fuel cell, so that the performance of the fuel cell is improved.

1 schematically illustrates the configuration of a general ammonia fuel-based solid oxide fuel cell stack.
FIG. 2 schematically shows before (a) and after (b) coating of the anode buffer metal mesh coated with the ammonia decomposition catalyst of the present invention.
FIG. 3 schematically shows a stack equipped with an anode buffer metal mesh coated with an ammonia decomposition catalyst of the present invention, that is, an anode buffer metal mesh composite.
4 is a graph comparing electrochemical performance of a fuel cell equipped with the anode buffer metal mesh composite of Example 1 of the present invention and the anode buffer metal mesh of Comparative Example 1 by measuring the electrochemical performances.
5 is a measurement of microstructure changes of each electrode of Example 1 and Comparative Example 1 after operating a fuel cell equipped with the fuel electrode buffer metal mesh composite of Example 1 of the present invention and the fuel electrode buffer metal mesh of Comparative Example 1 for 50 hours of operation is a source
6 is a graph showing the results of each of the metal meshes of Example 1 and Comparative Example 1 after 50 hours of operation of a fuel cell equipped with the fuel electrode buffer metal mesh composite of Example 1 of the present invention and the fuel electrode buffer metal mesh of Comparative Example 1, respectively. This is Ni ₃ N measurement data after X-ray diffraction analysis.
FIG. 7 shows the results of each metal mesh of Example 1 and Comparative Example 1 after 50 hours of operation of a fuel cell equipped with the fuel electrode buffer metal mesh composite of Example 1 of the present invention and the fuel electrode buffer metal mesh of Comparative Example 1. This is data comparing changes in nitrogen components, which are the cause of deterioration, measured by SEM-EDS.
8 is a graph comparing the electrochemical performances of fuel cells equipped with the fuel electrode buffer metal mesh composite (Mo coating) of Example 4 of the present invention and the fuel electrode buffer metal mesh of Comparative Example 3 by measuring changes over time.

Hereinafter, the present invention will be described in more detail to aid understanding of the present invention. At this time, the terms or words used in this specification and claims should not be construed as being limited to ordinary or dictionary meanings, and the inventor appropriately defines the concept of terms in order to explain his/her invention in the best way. It should be interpreted as meaning and concept consistent with the technical idea of the present invention based on the principle that it can be done.

The present invention relates to a high fuel cell (stack) including an anode buffer metal mesh composite coated with a catalyst material that promotes an ammonia decomposition reaction on an anode buffer metal mesh mounted in the anode region of a solid oxide fuel cell using ammonia as fuel. ), a solid oxide fuel cell stack for ammonia fuel having durability and performance, a manufacturing method thereof, and a solid oxide fuel cell for ammonia fuel including the stack.

In general, in a solid oxide fuel cell stack, a metal mesh or metal foam is used as a part that contacts a separator and an electrode (cathode: air electrode, anode: fuel electrode) and serves as a current collector.

Among the electrodes, the air electrode buffer metal mesh in contact with the air electrode uses a metal material that is stable even in a high-temperature oxidizing environment, and a metal material is used for the anode buffer metal mesh in contact with the anode, mainly nickel, which is stable and excellent in conductivity even in a high-temperature hydrogen supply environment. materials are used.

In addition, metal materials are used for stack components of fuel cells, such as separators, manifolds, and supply pipes, in addition to the electrodes of the cells.

The metal materials include noble metals, metals, alloys, and conductive ceramics.

In particular, in a solid oxide fuel cell using ammonia as fuel, when ammonia fuel is directly supplied to the stack of the fuel cell, corrosion such as nitration reaction (formation of nitrogen compounds) occurs on the metal surface of the anode and parts, The electrical resistance of the materials increases. Corrosion such as the nitridation reaction lowers the conductivity of the metal material of the anode, thereby reducing the performance of the fuel cell, and also causes deterioration in durability of the stack due to corrosion of the surface of the metal material.

In general, when ammonia is used as a fuel in a solid oxide fuel cell operating at a high temperature, a high concentration of ammonia is directly supplied to the anode of the stack. At this time, the electrode material of the anode not only participates in the electrochemical reaction required for power generation, At the same time, it should also serve as a catalyst for generating the ammonia decomposition reaction.

On the other hand, the higher the concentration of ammonia in the total fuel supplied to the anode, the lower the hydrogen concentration directly involved in the electrochemical reaction required for power generation. As a result, the performance of the fuel cell is reduced.

In addition, when high-concentration ammonia is directly supplied to the anode of the stack, the anode material participates in the ammonia decomposition reaction and thus participates less in the electrochemical reaction required for power generation, resulting in reduced performance of the fuel cell.

In addition, since the ammonia decomposition reaction at the electrode is an endothermic reaction that requires a lot of energy for decomposition, it may lower the operating energy of the fuel cell, thereby reducing the performance efficiency of the entire fuel cell.

In addition, when high-concentration ammonia is directly supplied to the fuel electrode, durability of the stack, that is, the fuel cell, is reduced due to corrosion such as formation of nitrogen compounds on the surface of metal or alloy materials of the electrode and components.

Since the problems of deterioration due to corrosion reactions such as nitration reaction on the surface of the metal material are caused by high concentration of ammonia when ammonia is used as fuel, in order to solve the above problem of deterioration, ammonia is applied to the anode as much as possible. It should be supplied in low concentrations.

In order to supply such low-concentration ammonia to the anode, there is a conventional method in which supplied ammonia is reformed with an ammonia reforming reactor device so that only low-concentration ammonia is supplied to the anode. However, the separate installation of the reactor device for ammonia reforming as described above requires enormous costs for installation and operation.

In the present invention, in order to prevent deterioration of the performance of the cell electrodes and parts of the stack even in an environment where ammonia fuel is supplied, the ammonia decomposition catalyst is coated on the anode buffer metal mesh or metal foam applied between the anode and the separator to prevent the ammonia decomposition catalyst from deteriorating. An anode buffer metal mesh composite is provided. The catalyst for decomposing ammonia of the provided composite decomposes some of the ammonia supplied at high concentration so that the ammonia supplied at the lowest concentration is supplied to the anode of the shell electrode equipped with the provided composite. Accordingly, corrosion such as nitration reaction of forming nitrogen compounds is prevented on the metal surface of electrodes and parts of the shell, thereby improving performance and durability of the fuel cell.

The metal materials include noble metals, metals, alloys, and conductive ceramics.

That is, some of the ammonia supplied from the ammonia buffer metal mesh composite coated with an ammonia decomposition catalyst material located in front of the anode is decomposed before reaching the anode, and ammonia at a low concentration is supplied to the anode, and accordingly, each metal in the stack is decomposed. Deterioration by ammonia is prevented in the material, and durability of the stack can be improved.

In addition, as described above, the concentration of hydrogen increases due to the ammonia decomposition reaction in the anode buffer metal mesh composite, and accordingly, the concentration of hydrogen supplied to the anode, which directly affects the electrochemical reaction required for power generation, increases, thereby improving cell performance. will also contribute to

In the following, first, a solid oxide fuel cell stack for ammonia fuel including the anode buffer metal mesh composite and the anode metal mesh composite for buffering, according to the present invention, will be described in detail.

The present invention provides an anode buffer metal mesh composite in which a part of the anode buffer metal mesh is coated with an ammonia decomposition catalyst, a manufacturing method thereof, and a solid oxide fuel cell stack for ammonia fuel including the same.

The ammonia decomposition catalyst coated on the anode buffer metal mesh composite may include at least one material selected from the group consisting of metals such as Ni, Ru, Co, Fe, and Mo, and ceramics having conductivity.

Among the ammonia decomposition catalysts coated on a portion of the anode buffer metal mesh to prepare the anode buffer metal mesh composite, the metal may be a metal oxide according to a coating method; metal salts; Alternatively, metal powder or the like is used. Metal oxides as needed for coating; metal salts; Alternatively, it may be provided in the form of a liquid composite in the form of a metal solution or paste such as metal powder and coated.

Since the anode of a fuel cell to which the ammonia decomposition catalyst material-coated metal mesh composite for anode buffer is applied is a high-temperature reducing gas environment, the coated catalyst material is finally the metal in the catalyst material in the anode metal mesh composite for buffer. Only exists and becomes coated.

In addition, when a conductive ceramic material is used as a catalyst for ammonia decomposition, a material having phase stability in a high-temperature reducing environment is used without composition change.

As a coating method for the ammonia decomposition catalyst, the coating using the metal solution in the liquid complex is a metal solution prepared by mixing a solvent-soluble metal-containing material, such as a metal salt or metal oxide, with a solvent to form an anode buffer metal mesh. By impregnation and drying, a metal mesh composite having a microstructure in which metal is uniformly dispersed on the surface of the anode buffer metal mesh may be manufactured. The solvent is a solvent in which the metal salt, metal oxide, and the like are dissolved.

In addition, the metal powder or ceramic material having conductivity is combined with a conventional organic or inorganic vehicle in a powder form to form a paste, and coated on the surface of the anode buffer metal mesh by a conventional screen printing method to prepare a metal mesh composite. can As the organic or inorganic vehicle, a conventional organic or inorganic vehicle may be used.

In addition to the above methods, as a method for coating a material for forming a catalyst on the surface of the buffer metal mesh of the anode, electroplating or electroless plating, chemical vapor deposition (CVD), physical vapor deposition (sputtering), thermal spray coating, dip coating, screen, if necessary Various methods such as printing and spin coating may be used.

In addition, the coated portion of the anode buffer metal mesh may be 0.1 to 99.9% of the total area of the anode buffer metal mesh, preferably an area excluding a part of the electrode effective contact surface, more preferably the electrode effective contact surface It may be an excluded area.

In addition, the coating thickness is characterized in that 2nm to 60㎛.

The present invention also provides a solid oxide fuel cell for ammonia fuel including the above solid oxide fuel cell stack for ammonia fuel.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

In the embodiment of the present invention, cell performance evaluation is performed by installing the following cell components in the basic solid oxide fuel cell evaluation device including fuel and air supply, temperature control, and electrochemical measuring devices (source meter, impedance, etc.) and proceeded.

a. metal manifold

The metal manifold is located at the top and bottom of the stack and is a part that uniformly distributes fuel and air when supplying the stack. When two or more cells are stacked, a metal separator (or end plate) and a frame are formed between them. Added.

The metal manifold is mainly made of an alloy-based material such as SUS or Inconel, and has high durability in a high-temperature environment of 750° C. or higher.

b. Air Cathode Buffer Metal Mesh

The air cathode buffer metal mesh is a component laminated between the upper manifold (or separator plate, end plate) and the air electrode of the cell, and is a connector or current collector that allows the air electrode and the separator to be electrically connected and contacted smoothly in a high temperature environment. and has the form of a mesh or foam to have flexibility and elasticity for this function.

The material of the cathode buffer metal mesh may be used by coating a conductive ceramic on a precious metal or alloy material such as platinum, gold, silver, etc., which can maintain electronic conductivity even in a high temperature and oxygen gas environment.

c. Fuel electrode buffer metal mesh

The anode buffer metal mesh is a component laminated between the lower manifold (or separator plate, end plate) and the anode of the cell, and is a connecting material or collector that allows the anode and separator of the cell to be electrically connected and contacted smoothly in a high-temperature environment. It has overall functions and has a form of metal mesh or metal foam to have flexibility and elasticity for these functions.

As the material of the anode metal mesh, noble metals such as platinum, gold, and silver, or metal and alloy materials, which can maintain electronic conductivity even in a high temperature and reducing gas environment, may be used. Nickel material with excellent conductivity and durability is mainly used.

d. Catalyst for decomposition of ammonia

The catalyst for decomposing ammonia may use a metal such as Ni, Ru, Co, Fe, Mo, Cr, or a metal material such as ceramic having conductivity. Conductive ceramics may be used for durability or composites of metals and conductive ceramics may be used.

e. solid oxide fuel cell cell

A solid oxide fuel cell cell is a component in which an electrochemical reaction between hydrogen and oxygen occurs at a high temperature, and is composed of an electrolyte, an anode, and an air electrode. , In the stack, the separators are alternately stacked and used.

The solid oxide fuel cell is composed of a composite material of metal and ceramic, and is classified into an electrolyte support type, an electrode support type, a ceramic support type, a metal support type, etc. manufactured, etc.

f. sealing material

The sealing material is a part that functions to block gaps between cells and separators in a stack when they are stacked, and must have high density and durability at high temperatures and excellent contact between cells and separators.

Since the sealing material has a melting point near a high temperature operating temperature or higher, a glass material having a certain viscosity or higher at the operating temperature is mainly used, and may be used together with a mica material.

In the present invention, the cell performance evaluation conditions were 50 cc/min of ammonia and 200 cc/min of air were supplied to the anode at an operating temperature of 750 ° C, and the power density according to the amount of applied current was measured using a sourcemeter, a measuring device, , In each condition, the stabilization time of the cell was maintained for more than 1 hour before proceeding.

<Example 1>

RuCl ₃ was added to ethanol to prepare a 0.2 M ruthenium chloride solution, and the anode buffer nickel mesh (area size of 10 mm x 10 mm and height 0.3 mm) in the area excluding the electrode contact surface was coated with the ruthenium chloride solution three times, It was dried at 60° C. using a hot air dryer, and after drying, an anode buffer nickel mesh composite having a coating thickness of 2.5 nm was obtained (see FIG. 2 (b)).

The anode buffer nickel mesh composite coated with Ru metal was mounted in the anode region, and ammonia was directly supplied to the anode to perform evaluation.

<Example 2>

As a coating solution, Fe ₂ O ₃ powder was mixed with an organic vehicle (FCM, USA) in a weight ratio of 5:5 to prepare Fe ₂ O ₃ paste and coated with a thickness of 10 to 20 μm, as in Example 1 above. Thus, an anode buffer nickel mesh composite coated with the Fe metal was prepared.

Evaluation was performed by mounting the anode buffer nickel mesh composite coated with Fe metal on the anode region and directly supplying ammonia to the anode.

<Example 3>

An anode buffer nickel mesh composite coated with the Mo metal having a thickness of 10 to 20 μm was prepared in the same manner as in Example 2, except that MoO ₂ powder was used to prepare the coating solution.

The anode buffer nickel mesh composite coated with the Mo metal was mounted in the anode region, and ammonia was directly supplied to the anode to perform evaluation.

<Example 4>

Evaluation was conducted in the same manner as in Example 3, except that the ammonia fuel was passed through the ammonia reforming reactor device (temperature 650 degrees, Ni/Al ₂ O ₃ catalyst 5g) and then supplied to the cell region.

<Comparative Example 1>

The evaluation was conducted in the same manner as in Example 1, except that the nickel mesh was not coated with the catalyst.

<Comparative Example 2>

The anode buffer nickel mesh composite prepared as in Example 1 and coated with Ru metal was mounted on the anode area and evaluated as in Example 1, except that the entire surface of the anode nickel mesh was coated with the catalyst.

<Comparative Example 3>

The evaluation was performed in the same manner as in Example 4, except that the nickel mesh was not coated with the catalyst.

The comparison results for Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1 and FIGS. 4 to 8 below.

Table 1 below shows the results of measuring and comparing changes in electrochemical performance over time according to the type of decomposition catalyst coated on the anode buffer metal mesh composite of the present invention.

Early stage
electrochemical performance
(Unit: mW/cm ² ) after 20 hours
electrochemical performance
(Unit: mW/cm ² ) after 50 hours
electrochemical performance
(Unit: mW/cm ² ) Example 1 290.08 260.24 228.4 Example 2 278.72 252.31 223.58 Example 3 269.28 252.48 223.2 Comparative Example 1 259.68 239.8 203.49

As shown in Table 1, it can be seen that the electrochemical performance of the fuel cell of Examples 1 to 3 coated with the catalyst of the present invention is superior to that of Comparative Example 1 not coated with the catalyst, and even after long-term operation after 50 hours, the present invention is still Examples 1 to 3 of the invention show that the electrochemical performance of the fuel cell is superior to that of Comparative Example 1. It can be seen that the durability and performance of the fuel cell are improved due to the increased durability of the stack including the anode buffer metal mesh composite of the present invention.

4 shows Example 1 (coating of the portion of the ammonia decomposition catalyst excluding the electrode effective contact surface) and Comparative Example 2 (electrode of the anode buffer metal mesh) according to the catalyst material coating application area of the buffer mesh coated with the catalyst for decomposition of ammonia It is a graph comparing the electrochemical performance of the entire surface including the effective contact surface).

For measurement, an hourly I-V test (voltage value according to current density) was performed to calculate the power density according to the current (current density X voltage), and the calculated power density values were summarized and displayed on the graph.

As shown in FIG. 4, as a result of the evaluation of Example 1 and Comparative Example 2, the performance of Example 1, in which the catalyst was coated on a portion of the nickel mesh and applied, was higher, and the performance of Comparative Example 2, in which the entire surface of the nickel mesh was coated, was shows a significant decrease.

This is because the coated catalyst promotes the decomposition reaction of ammonia and increases the hydrogen concentration (partial pressure), but is coated on the nickel mesh of the effective contact surface of the electrode, and interface resistance is additionally generated by the new interface by the coating, resulting in reduced performance. judged

FIG. 5 shows SEM image analysis of a cross-section of an anode electrode layer of a cell after evaluation of ammonia supply for each cell of Example 1 and Comparative Example 1. FIG. From the SEM image of FIG. 5, in Comparative Example 1, the surface of the nickel crystal grains of the fuel electrode was transformed into an angular microstructure, but the nickel mesh according to Example 1 of the present invention was coated with ruthenium, an ammonia decomposition catalyst. It was confirmed that the surface of the nickel crystal grains of the anode of the cell was not deformed compared to the result of Comparative Example 1. From the result of the microstructure of the electrode in Comparative Example 1 being modified, it can be seen that the deterioration of the cell due to ammonia proceeds. The results of FIG. 5 confirm that the deterioration of the cell by ammonia affects the performance or durability of the fuel cell in relation to Table 1 above.

FIG. 6 shows an X-ray diffraction analysis of the anode buffer nickel mesh composite after evaluating the supply of ammonia for each cell of Example 1 and Comparative Example 1. FIG. In Comparative Example 1, the crystal phase of nickel nitride (Ni3N) was clearly measured along with the nickel crystal phase in the nickel of the anode, but the anode of the cell in which the nickel mesh of Example 1 of the present invention was coated with ruthenium, an ammonia decomposition catalyst was applied. In nickel, it was confirmed that only a very small amount of the crystal phase of nickel nitride (Ni ₃ N) was confirmed compared to the result of Comparative Example 1. Nickel nitride shown in Comparative Example 1 may cause adverse effects on performance because it lowers conductivity or catalytic activity (see Table 1 above).

FIG. 7 shows the results of SEM-EDS component analysis of the cell fuel electrode after ammonia supply was evaluated for each cell of Example 1 and Comparative Example 1.

The measurement range of the analysis was specified by limiting only the anode electrode layer in the cross section of the cell, and as a result of confirming the SEM-EDS component analysis, Comparative Example 1 had 1.60% of the nitrogen component representing the result of nitration by ammonia (analysis area of the analyzer While the amount of nitrogen component relative to 100%, which is the sum of all components in the range (sem photo)), Example 1 of the present invention has a nitrogen component detection amount of 0.85%, which is reduced by 1/2 compared to Comparative Example 1 has been detected These results indicate that the fuel electrode buffer metal matrix composite of the present invention also affects the rate of degradation of the electrode (fuel electrode) due to the nitrification phenomenon. It can be seen that this is a factor affecting performance.

FIG. 8(a) is a schematic diagram illustrating an operating environment in which the concentration of supplied ammonia is lowered by adding an ammonia reforming reactor device at the front of the cell, which is a method generally applied to commercial high-temperature fuel cell systems.

8(b) is a comparison of Example 4 in the case where the anode buffer nickel mesh is coated with Mo metal and the anode buffer nickel mesh that is not coated with Mo metal, in the operating environment of the ammonia reforming reactor device of 8(a). It is a graph measuring the performance change over time of the electrochemical performance for Example 3.

For measurement, an hourly I-V test (voltage value according to current density) was performed to calculate the power density according to current (current density X voltage), and the maximum value of power density was summarized and displayed on the graph.

As a result of the above evaluation, it can be confirmed that the fuel cell performance over time of Example 4 in which the Mo catalyst was applied to the nickel mesh was maintained higher than that of Comparative Example 3 in which the catalyst was not coated, indicating that the catalyst was coated on the anode buffer metal mesh of the present invention. This shows that when an anode buffer metal mesh composite is applied to the shell of the stack, the effect of preventing deterioration of the stack is great. It can be confirmed that this anti-deterioration effect eventually has excellent durability (performance retention rate over time).

As described above, the solid oxide fuel cell stack for ammonia fuel including the anode buffer metal mesh composite of the present invention can contribute to performance improvement and durability of the fuel cell for ammonia fuel use, and thus industrial use of the solid oxide fuel cell for ammonia fuel. Chances are high.

The present invention has been described above using several preferred examples, but these examples are illustrative and not limiting. As such, those skilled in the art to which the present invention belongs will understand that various changes and modifications can be made according to the doctrine of equivalents without departing from the spirit of the present invention and the scope of rights set forth in the appended claims.

The present invention is a research project (project title: ammonia-based solid oxide fuel cell electrode material and cell manufacturing This is the result of technology development, task number: CBTP-B-20-04-R001, research period: 2020.11.01.~2021.10.31.).

Claims (13)

An anode buffer metal mesh composite, characterized in that a catalyst for ammonia decomposition is coated on an anode buffer metal mesh or metal foam applied between the anode and the separator of the solid oxide fuel cell shell for ammonia fuel and composited. According to claim 1,
The ammonia decomposition catalyst comprises at least one material selected from the group consisting of metals of Ni, Ru, Co, Fe, and Mo and ceramics having conductivity, the anode buffer metal mesh composite According to claim 2,
Characterized in that the coating thickness of the catalyst is 2 nm to 60 μm, the anode buffer metal mesh composite According to claim 1,
The ammonia decomposition catalyst is characterized in that coated on a portion of the anode buffer metal mesh or metal foam, the anode buffer metal mesh composite According to claim 4,
The portion is 0.1% to 99.9% of the entire surface of the anode buffer metal mesh or metal foam, characterized in that, the anode buffer metal mesh composite A method of manufacturing an anode buffer metal mesh composite in which an ammonia decomposition catalyst is coated on an anode buffer metal mesh or metal foam applied between the anode and the separator of a solid oxide fuel cell shell for ammonia fuel,
The catalyst for decomposing ammonia comprises at least one material selected from the group consisting of metals of Ni, Ru, Co, Fe, and Mo and ceramics having conductivity, a method for producing an anode buffer metal mesh composite According to claim 6,
The metal may be a metal oxide depending on the coating method; metal salts; Or metal powder is used, and metal oxide; metal salts; Or, a method for producing an anode buffer metal mesh composite, characterized in that it is provided as a liquid composite in the form of a metal melt or paste of metal powder and coated. According to claim 6,
The coating thickness of the catalyst is Method for manufacturing an anode buffer metal mesh composite, characterized in that 2 nm to 60 μm According to claim 6,
The ammonia decomposition catalyst is a method for producing an anode buffer metal mesh composite, characterized in that coated on a portion of the anode buffer metal mesh or metal foam. According to claim 9,
The portion is 0.1% to 99.9% of the entire surface of the anode buffer metal mesh or metal foam, characterized in that, a method of manufacturing an anode buffer metal mesh composite A solid oxide fuel cell stack for ammonia fuel, characterized in that it comprises the anode buffer metal mesh composite of any one of claims 1 to 5 A solid oxide fuel cell stack for ammonia fuel, characterized in that it is manufactured using the fuel electrode buffer metal mesh composite manufactured by the manufacturing method of any one of claims 6 to 10. A solid oxide fuel cell for ammonia fuel, characterized in that manufactured by including the solid oxide fuel cell stack for ammonia fuel of claim 11 or 12

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