JP5099892B2 - Manufacturing method of membrane electrode assembly for highly consistent solid oxide fuel cell - Google Patents

Description

  The present invention relates to a new manufacturing method for preparing a raw material into an electrode for use in a flat plate type SOFC-MEA by a special method. In the manufacturing method, an electrode substrate green sheet is manufactured by a sheet casting process comprising an anode and an electrolyte substrate electrolyte. The green sheet is formed on a green sheet substrate by a laminating process, and further formed on a final green sheet substrate that is highly aligned by a high vacuum sintering system (VHPS for short).

This green sheet for a substrate has a high mechanical strength by calcining / sintering treatment, and can produce an electrode substrate capable of controlling the characteristics, thickness and size of the microstructure. In addition, high-performance SOFC battery cells can be made by coating processes such as screen printing / sputtering coating / spin coating / spray. Such SOFC batteries have excellent performance such as high stability, durability and low deterioration rate.

  There are many types of materials such as YSZ / GDC / YDC / LSGM for the electrolytes mentioned in the text, NiO + YSZ / GDC + NiO / YDC + NiO / LSGM + NiO for anode materials, and LSM / LSCF for cathode materials. It is not limited to said material kind.

  SOFC aims to solve the future energy shortage problem that replaces internal combustion engines with high conversion efficiency, low noise and low environmental pollution, high reliability and many characteristics such as fuel multipleness . In particular, in the future when petrochemical energy is depleted, it is expected that SOFC will play a role in creating a new era as an essential part of energy conversion equipment in the time of replacement with hydrogen energy or gas / liquefied fuel.

  The goal of the currently developed Planar Type Solid Oxide Fuel Cell-Membrane Electrode Assembly (SOFC-MEA) is the high operability of MEA (High Performance, durability (High Durability), stability (High Stability) and low degradation rate (Low Degradation Rate). The critical conditions for achieving the above goals are the materials and structural design used in the MEA. Changing the MEA material content and structure will change the properties of the MEA. In terms of materials, the electrolyte mainly depends on the structure of the substrate that supports the optimum operating temperature, mainly 8YSZ. The operating temperature of an electrolyte supported cell (ESC for short) is optimally between 800-1000 ° C, and the thickness of the electrolyte substrate is 150-300μm, which is the first generation Belongs to SOFC-MEA. The operating temperature of the anode supported cell battery cell (ASC for short) is 650 to 850 ° C., the thickness of the electrolyte substrate is 10 μm, and it belongs to the second generation SOFC-MEA. NiO + 8YSZ is an ASC / ESC anode material with thicknesses of 50-60 μm (ESC) and 500-1200 μm (ASC), respectively. As the cathode material, LSM and LSCF are mainly used, and the thickness thereof is 30 to 60 μm. New electrolyte materials and cathode materials have recently been researched and developed in various laboratories around the world, and the expectation for the new materials is that the operating temperature of SOFC-MEA is lowered to 500-700 ° C, and the battery stack It is to change the interconnector of assembly parts from metal material to ceramic material. This makes it easier to manufacture parts, improves mechanical stability and durability, expands SOFC market competitiveness and dissemination capabilities by reducing overall costs, and creates a huge niche market for SOFC industry. Create. The development of this technology is focused on the research and development of materials in universities and national laboratories by lowering impedance and improving ionic conductivity / conductance and increasing SOFC electromotive current supply density. . For example, LSGM, YDC, LSGMC, 10ScCeSZ are used as new electrolytes, and LSM / LSCF / LSF / LSC / LSCM / BSCF / SSC are used as new cathode materials. There is something. Since it is developed with emphasis on the manufacturing technology and performance stability of material processing in the industry, a target material that can sufficiently understand the characteristics and is reliable is selected. SOFC-MEA manufacturing method and structural design improve the mechanical strength or mechanical stability, mechanical durability, durability, and energy conversion efficiency and output of battery cells (MEA). Aim to do.

  National laboratory facilities around the world spend approximately 15 to 20 years of investment and development to verify SOFC functionality, overcome technical obstacles, and create business opportunities. For this reason, international companies have established joint ventures in cooperation with national experimental facilities to exchange, streamline or collaborate with human resources.For example, in Europe, ECN and InDEC / HCStark, IKTS / Karafol and Straxera / Examples include Webasto, NETL / SECA and EPFL / HT Ceramix. In the US, as a national experimental facility, PNNL commissions R & D to six major companies such as Simens Westinghouse, GE, Delphi, etc. to verify the reliability of new technology, analyze costs and lower SOFC The industry is being actively built.

  Products commercialized in SOFC-MEA related materials mainly use 8YSZ electrolyte, NiO + 8YSZ anode, LSM / LSCF and LSF / LSC cathode as mentioned above. The MEA manufacturing method is an intellectual property right owned by each company, so it is rarely disclosed, and it is publicly known by patent applications and can be used by others, or the rights can be impaired by an improved invention of patent contents. In some cases, patent applications may be avoided.

However, the current general SOFC-MEA manufacturing method uses a sheet forming technique to create a green sheet for an electrode, adjusts the thickness and geometric structure of the substrate by laminating, and calcines and sinters the electrode. A substrate or a half-cell substrate (including an electrolyte layer and a supporting electrode layer) is formed, and finally a cathode layer is placed on the half-cell substrate by a screen printing technique to complete the SOFC-MEA. The SOFC-MEA produced in this way has disadvantages such as insufficient mechanical strength, poor stability and durability (antioxidant reduction cycling (Redox Cycling) / anti-temperature cycling). The cathode and the anode cannot maintain the mechanical strength under the basic requirement that a clearance is required, and the battery stack assembly pack is likely to be ruptured or damaged. SOFC has not been overcome by this drawback, so a solution is desired.
JP 2006-351403 A WO2003 / 098724

  The present invention provides a means and a manufacturing method for preparing a highly consistent solid oxide fuel cell membrane electrode assembly or battery cell (abbreviated HI-SOFC-MEA or HI-Unit Cell).

This HI-SOFC-MEA has the following properties:
1. High mechanical strength and rigidity.
2. The porosity and air permeability of the substrate can be adjusted.
3. MEA controllable multi-layer material and microstructure or density are achieved.
4). The number of MEA layers and the thickness of each layer can be controlled.
5. High density sintering
6). High stability and steady operating capability.
According to the above characteristics, this HI-SOFC-MEA raises battery power density and fuel energy conversion rate, and the most important feature is high mechanical strength improvement, which results from cell weakness during battery stack assembly and measurement The product can be prevented from bursting and the reliability and yield of the product can be prevented from being lowered.

  In order to solve the above-mentioned problems, the manufacturing method of the highly consistent solid oxide fuel cell membrane electrode assembly of the present invention is divided into its means and two manufacturing processes (electrode green sheet and electrode substrate manufacturing). Each will be described as follows.

(1) Formulation and manufacturing method of slurry for electrode substrate manufacturing.
Table 1 shows a typical slurry recipe for a SOFC-MEA electrode substrate.

Notes: a. Compound molecular formula is shown in Table 2. b. QOV = Quasi-Optimium Value. c. Other types of organic additives can be used as required, but the final stickiness range of the slurry used in the scraper molding method is determined to be 100-1500 cP , corresponding to the preferred green tape thickness. Choose. d. Other usable electrolyte materials: GDC / YDC / SDC / LSGM, etc.
Mainly used materials are classified as follows: a. Electrode materials include electrolyte 8YSZ and anode material NiO + 8YSZ. b. Organic additives are organic solvents (MEK, EtOH), dispersants (TEA), plasticizers (DBP, PEG), bonding (viscosity) agents (PVB), c. pore formers.
(Graphite). The distribution contents of the weight percentage of the formulation of each material are shown in Table 1, and the compound molecular formula or the contents of the components are shown in Table 2.

The optimum compositional values for the electrolyte substrate / layer component recipe are: 8YSZ (68 wt%), MEK (17 wt%), EtOH
(7 wt%), TEA (1.5 wt%), DBP (1.0 wt%), PEG (1.0 wt%), PVB
(4.5 wt%), pore former (0. wt%). It is not necessary to use a pore-forming agent because the electrolyte layer is required to have a gas passing rate of zero and a density of 100 percent. And the optimum compositional value of the composition of the anode substrate / layer composition is: NiO + 8YSZ (68 wt%) (of which NiO / 8YSZ weight ratio is 50/50 (best value approximate)), MEK (17 wt% ), EtOH (7 wt%), TEA (1.5 wt%), DBP (1.0 wt%), PEG (1.0 wt%), PVB (4.5 wt%), pore former (graphite) (anode material weight 0.1 ~ 10 wt%). The pore forming agent can be adjusted according to the demand for the porosity of the anode substrate. The weight percentage range of the formulations shown in Table 1 can be adjusted according to the powder properties (such as powder diameter distribution or surface area size) of the electrode material. The goal is to make a green sheet product with a high average degree suitable for the operating variables of the sheet forming method and the characteristics of the green sheet product. The electrode material and pore former in this formulation require pretreatment, and the main method is to grind the electrode material to a powder diameter of 200 to 300 nm with a ball mill, and then use a ball mill with an organic solvent and a dispersing agent to Grind and homogenize for about 48 hours. Finally, a plasticizer and a binder are added, and both are ground for about 24 to 48 hours to complete the homogenization and slurrying of the slurry. Thus, the slurry components and viscosity are adjusted according to the required green sheet thickness, and the sheet forming method is dealt with. If the thickness of the green sheet is 10-200 μm, the viscosity range should be reduced to between 100-1500 cP (this also depends on the properties of the first powder object, but by experimental confirmation deal with.). The operation of the sheet forming system requires skill, but a green sheet having the required characteristics can be obtained by executing the process according to the operation procedure of the sheet forming machine.

(2) Manufacturing process of electrode substrate:
The manufactured green sheet product described in (1) above is made into a single-layer green sheet section of a specific size through a punching / blanking process. The number of green sheets is determined, inspected, stacked, and a green substrate for electrode-A having a predetermined thickness is formed by a hot press lamination process (Lamination Process). The temperature and pressure of the hot-press lamination process are 60 to 100 ° C. and 14 MPa to 34 MPa (2000 psi to 5000 psi), respectively, and the density of the green substrate-A at this time is approximately 40% of the theoretical density of the ceramic oxide. . The green substrate-A is prepared by the second stage “vacuum hot-pressure compaction method”. The degree of vacuum in this method is 10 ⁻³ to 10 ⁴ torr , and pressure = 1,152 to 104 MPa [1.68 × 10 ⁵ psi (area = 9 cm ² ) to 1.52 × 10 ⁴ psi (area = 100 cm ² )] And temperature = 500
The density of the green sheet B can be 70% of the theoretical density of the electrode ceramic oxide. This “two-stage vacuum hot-press laminate” is a new synergistic process (Novel
Synergistic Process) ”and abbreviated as NSP. In the LP stage, the green sheet is laid on the ironing board and processed, but the green sheet in the "vacuum hot-pressure sintering system (VHPS for short)" stage is sealed in a mold of the required size and the related processing operations are performed. . “High Integrity” is given to the substrate of the electrode green sheet by the NSP method,
The electrode ceramic substrate after calcining / sintering is provided with both high consistency and high mechanical strength. Furthermore, the battery cell of the present invention is subjected to other electrode layer processing / manufacturing methods such as silk screen (Screen Printing) , sputtering coating (Sputtering Coating), plasma coating (Plasma Coating / Spraying) , and spin coating (Spin Coating). Form.

  The fuel cell of the present invention is referred to as a “highly consistent fuel cell membrane electrode assembly” because it has high mechanical strength (which can be used for measurement of cell stack sealing) and high durability and stability. And by changing the amount of pore-forming agent used to adjust the microstructure inside the anode substrate, the porosity between each layer can be changed, or the gas passage rate can be increased to improve the energy conversion efficiency and power density of the battery cell I can do it. Therefore, it is possible to improve the precision and performance of the product as a SOFC-MEA manufacturing technology.

The SOFC-MEA material formulation and method thereof of the present invention is a method for producing “a highly aligned fuel cell membrane electrode assembly or battery cell”, the content of which is a component formulation and a green sheet substrate and an electrode ceramic substrate. There are two manufacturing methods.
Details will be described below.

(1) The component prescription and manufacturing method of the slurry of the green sheet of the electrode substrate include the following processes and steps.

Step 1: Mix 8YSZ and NiO powder, adjusted as appropriate, or in a certain weight ratio (NiO accounts for 35-65 wt% of the total weight of NiO + 8YSZ (QOV value is 50 wt%)), Place in a mill bottle with a zirconium dioxide mill ball for 24 to 168 hours (adjust as needed) to obtain a uniformly mixed powder. Using the average particle size of the powder as a guideline to 300 to 500 nm, the uniformity is determined by sample analysis by SEM (adjusted as necessary), and the grinding time and mill rotation speed are changed. This powder is hereinafter referred to as Anode-P-1, and is stored in a database with characteristics such as particle size, surface area, and uniformity (EDX-Mapping). The above is the component formulation of the slurry for producing the electrode green sheet, and details are shown in Table 1.

Step 2: Take out powder Anode-P-1 and place it on a zirconium dioxide plate, sinter at 1200-1600 ° C for 2-8 hours in a high-temperature furnace, grind it with a mill ball according to the method of Step 1, Once the powder has an average particle size range of 300-500 nm (or adjust as needed). This powder is hereinafter referred to as Anode-P-2. In order to adjust the porosity of the final substrate, Anode-P-2 is added with an appropriate amount of pore former (Pore former: a typical material used) and then ground. By repeating the process for several hours (ideally 24 hours or more), a powder called Anode-P-3 is obtained.

Step 3: Take a fixed amount of Anode-P-3 and dry at 100 ° C for tens of hours (ideally 24 hours or more to remove moisture and moisture). In addition, the organic solvent MEK / EtOH and the dispersant TEA, both of which are determined in accordance with the ratios shown in Table 1, are placed in a mill bottle equipped with zirconium dioxide balls for several tens of hours (24 hours or more is ideal), and then ground to the whole. Ensure uniform uniformity. This homogeneous solution of homogeneous solvent and dispersant is hereinafter referred to as SD.

Step 4: Add dry powder Anode-P-3 to the SD solution and grind in the liquid phase for tens of hours (ideally 48 hours or more) to evenly dissolve the powder in the solvent / dispersant, A mixed slurry, hereinafter referred to as SL-1, was formed.

Step 5: According to the recipe in Table 1, add a certain amount of plasticizers DBP, PEG and binder PVB to slurry SL-1 and grind in the liquid phase for tens of hours (about 48-72 hours) What confirmed the property is hereinafter referred to as SL-2 as a slurry for an anode substrate of this sheet forming method. Check the properties while measuring the viscosity of SL-2 with a viscometer.

Step 6: Using micro-adjustment, add the appropriate amount of binder at each stage, and make the viscosity of SL-2 150-150 cP with plasticizer (QOV = 200-500 cP ). This adjustment determines the order and time empirically depending on the coordinator's experience and skills / abilities. The finally completed tape slurry is hereinafter referred to as SL-T.

Step 7: Process the sheet slurry SL-T with a tape casting system to form a green sheet. The width of the green sheet is approximately 18 to 30 cm, and the thickness of the single layer is 10 to 300 μm (the thickness of the single layer can be increased according to the performance of the sheet molding machine as necessary).

Step 8: Cut green sheets into single pieces of specific size and shape (usually square or round) with a cutting tool or punch, and laminate the green sheet pieces to the desired thickness A predetermined green sheet substrate (referred to as GT-1) is produced by performing an operation of laminating with an apparatus (hereinafter referred to as LM). The pressing force of this laminating apparatus is set to 60 to 100 ° C. and 14 MPa to 34 MPa (2000 psi to 5000 psi), the temperature is 50 to 100 ° C., the thickness of GT-1 is 100 to 1500 μm, or the thickness of the substrate The thickness is set to QOV = 600 to 1200 μm. The density of the green sheet of GT-1 is measured with Pychrometer.

(2) Manufacturing method of electrode ceramic substrate:
Step 1: Green tape substrate (GT-1) (size is 5 x 5cm ² to 15 x 15cm ² (or more) thickness is 600 to 1200μm) 5 x 5 cm ² or appropriate size Put it in a mold and send it to the “vacuum hot pressure sintering system (abbreviated VHPS) (Fig. 2)”, vacuum (<1 × 10 ^-3 torr ), hot pressure (temperature <500 ° C, pressure up to 1,152 MPa) (1.68 x 10 ⁵ psi) (adjustable type)). When a high-density green tape substrate (called GT-2) created by this method is measured with Pychrometer, the density of the green tape is increased to 70% of the theoretical density of the corresponding ceramic oxide.

Step 2: If necessary, the surface preparation of GT-2 is repeated with the laminating device. The method by which the two systems of LM and VHPS alternately strengthen the green sheet substrate is called “A Novel Synergistic Process”, and finally the green sheet substrate called GT-F is formed.

Step 3: GT-F is sandwiched and fixed on both sides by a zirconium oxide substrate (sandwich structure), and the setter is circulated and sintered in two stages in a high temperature furnace (up to 1700 ° C) made of alumina oxide. Temperature control of the first circulation: room temperature → 200 ° C (4Hr) → 450 ° C (2Hr) → 750 ° C (2Hr) → 1250 ° C (6Hr) → room temperature, temperature control of the second circulation: room temperature → 1400 ° C ( 4Hr) → room temperature. While maintaining the rate of temperature rise and fall circulating in two stages at 1 ° C / min (best within 3 ° C / min), introduce an appropriate amount of air at the same time. The first circulation removes all organic additives by calcination. The second circulation is densified by sintering to form a ceramic substrate. The completed electrode substrate is hereinafter referred to as AS-1, and the characteristics such as sintering density, mechanical strength, porosity, and microstructure are evaluated. The AS-1 electrode substrate thus formed has high mechanical strength and flatness, an appropriate porosity and gas passage rate, and satisfies the basic requirements of the SOFC-MEA electrode structure.

Step 4: Suitable thickness (<10μm) for AS-1 with equipment and methods such as Silk Screen (Screen Printing) / Sputtering Coating / Spin Coating / Plasma Spray Apply an optimal electrolyte (8YSZ) layer and sinter (1400 ℃ / 4Hr) in a high temperature furnace. The rate of temperature increase / decrease is 1 ℃ / min. The manufactured SOFC-MEA half-cell is hereinafter referred to as AS-H.

Step 5: The AS-H half-cell is coated with an LSM (or material such as LSCF) cathode layer on the YSZ layer by silk screen technology and sintered in a high temperature furnace to a thickness of 30-50 μm. The rate of temperature increase / decrease is 1 ° C / min (optimally less than 3 ° C / min). The obtained finished product is an anode-supported battery, hereinafter referred to as ASC-I (or ASC-type SOFC-MEA) (for details, an anode substrate (NiO + YSZ) having plural / functional layers shown in FIG. 3). .

According to the above method, the anode-supported cell type SOFC battery converts various fuels such as hydrogen, gas, and carbohydrates directly into electric power as an energy source and outputs it to the electric power supply.
Hereinafter, the present invention will be specifically described based on examples.

(Example 1) Production of SOFC anode substrate and battery cell having high mechanical strength and optimum porosity.

In this example, a flat plate-type SOFC anode substrate having high mechanical strength and an optimum porosity is manufactured, and then a SOFC battery cell is completed. The production method consists of two stages. The first stage consists of (1) the total component formulation and manufacturing method of the slurry for manufacturing the NiO + YSZ anode substrate green sheet, and (2) the manufacturing method of the anode ceramic substrate consists of a total of 5 steps. Hereinafter, it will be described in segments.

(1) The formulation and manufacturing method of the slurry for manufacturing the green sheet of the NiO + 8YSZ anode substrate includes the following steps (details are shown in FIG. 4).

Step 1: Mix 175 grams of Cubic crystal structure 8YSZ with an equal amount of nickel oxide (NiO) (average particle size is about 1000 nm) to form zirconium oxide (ZrO2) mill balls (about 250 In a ball mill bottle with gram), and thoroughly mixed NiO and 8YSZ by grinding for about 168 hours to obtain a highly uniform mixed powder. The uniformity is determined by analyzing the sample with SEM. As a grinding target, the average particle size of the powder is 300 to 500 nm, and the grinding time and rotation speed are appropriately increased as necessary. The powder in this section is called Anode-P-1, and all the powder characteristics such as particle size / surface area ratio / uniformity are stored in the database.

Step 2: Remove the powder Anode-P-1 from the mill bottle and perform co-sintering at 1400 ° C for 4 hours in a high-temperature furnace on a zirconium oxide plate. After completion, the grinding process in Step 1 is repeated, and the particle size of the powder is increased to 300 to 500 nm by another ball mill to increase the uniformity. This co-sintered powder is called Anode-P-2. High uniformity is ensured by adding 3.5g submicrometer / nanometer graphite powder to Anode-P-2 and repeating grinding for more than 24 hours. The powder thus obtained is called Anode-P-3 and has a total weight of 353.5 g.

Step 3: Take 353.5g of Anode-P-3 and dry at about 100 ° C for more than 24 hours to remove moisture and moisture from the powder. In addition, weighed 78.1g of solvent MEK, 25.27g of EtOH and 8.05g of TEA dispersant, and put them together into a mill bottle equipped with zirconium oxide balls (ZrO2 Ball). Secure. This uniform liquid phase of the solvent and the dispersant is called SD solution and has a total weight of 111.42 g.

Step 4: Add dried powder Anode-P-3 to the SD solution and grind it in the liquid phase for 48 hours or more to disperse the powder uniformly in the solvent / dispersant. Become. The total weight of SL-1 at this time was 464.92 g.

Step 5: Weigh plasticizers DBP4.59g, PEG4.59g, and binder PVB19.55g and add them to slurry SL-1 respectively and grind in liquid phase for more than 48 hours to ensure complete homogenization of the whole. The anode substrate slurry for use in the sheet forming method is called SL-2 and has a total weight of 463.65 g. Further check and record the viscosity and properties of SL-2 with a viscometer.

Step 6: Using micro-adjustment technology, add the appropriate binder PVB / plasticizer DBP / PEG for each step and adjust the viscosity of SL-2 to between 150-1500 cP (the best viscosity is 200-500 cP) At the same time, check the forming degree of the corresponding green sheet. In this adjustment, the order and time are determined empirically by the coordinator's experience and skills / abilities. Finally, a suitable scraper slurry (Tape
The viscosity of Slurry or Slip slurry (SL-T for short) is 328 cP . (Details are shown in Fig. 5)

Step 7: Scraper slurry SL-7 is processed by a sheet molding machine (Tape Casting System) to produce a green sheet. The width of the green sheet is determined according to the dimensions of the designed sheet forming machine and is about 18 to 20 cm. The thickness as a single layer is 100 μm, and the length is determined by the amount of Anode-P-1 powder added. (Details are shown in FIG. 6).

Step 8: Cut the green sheet into 5 × 5cm ² or 10 × 10cm ² (the size and shape can be adjusted as necessary) with a cutting tool or punch into a single layer with a thickness of 100 μm. A single sheet of green sheets is stacked and laminated with a laminating machine (referred to as LM) to produce a standard (square) green sheet substrate (referred to as GT-1) with a thickness of 1200 μm. Here, the pressure of the laminating apparatus is set to 14 MPa to 34 MPa (2000 to 5000 psi), the temperature is set to 50 to 100 ° C., and the density of the green sheet of GT-1 is measured with Pychrometer. (Details are shown in Fig. 7)

(2) The manufacturing method of the anode ceramic substrate is as follows.

Step 1: Put green tape substrate GT-1 (square dimensions 5 x 5 cm ² to 15 x 15 cm ² (or more) thickness 600 to 1200 µm) into 5 x 5 cm ² or appropriate size mold , Sent to "vacuum hot-pressure sintering system (VHPS for short)", vacuum (<1 × 10 ^-3 torr ), hot pressure (temperature <500 ° C, pressure up to 1,152 MPa (1.68 × 10 ⁵ psi) Reach (adjustable type)). When a high-density green tape substrate (called GT-2) made by this method is measured with Pychrometer, the density of the green tape is improved to 70% of the theoretical density of the corresponding ceramic oxide.

Step 2: If necessary, the surface of GT-2 is laminated again by LM machine. This method of alternately reinforcing the green sheet substrate by the two processes of LM and VHPS is called “A Novel Synergistic Process”, and finally a green sheet substrate called GT-F is manufactured. The size of GT-F is determined by product requirements and hot-press mold dimensions.

Step 3: The GT-F is sandwiched and fixed by a zirconium oxide substrate from above and below (sandwich structure), and the setter is made of alumina oxide and sintered in two stages in a high-temperature furnace (up to 1700 ° C). Temperature control of the first circulation is: room temperature → 200 ° C (4Hr) → 450 ° C (2Hr) → 750 ° C (2Hr) → 1250 (6Hr) → room temperature, temperature control of the second circulation is: room temperature → 1400 ° C (4Hr ) → Room temperature. While maintaining the temperature increase / decrease rate of the two-stage circulation at 1 ° C / min (within 3 ° C / min is optimal), allow an appropriate amount of air to pass through at the same time. The electrode substrate completed in production is called AS-1, and the evaluation for its characteristics is shown in Table 3.

 The AS-1 electrode substrate thus obtained has high mechanical strength, flatness, moderate porosity and gas passage rate, and satisfies the basic requirements of the SOFC-MEA anode structure. (Details are shown in Fig. 9)

 Step 4: Apply an electrolyte (material 8YSZ) layer with a thickness of about 10μm to the anode substrate AS-1 using screen printing equipment and method, and sinter at 1400 ℃ / 4Hr in a high temperature furnace at 1700 ℃. To do. The rate of temperature increase / decrease is 1 ° C / min. The SOFC-MEA half-cell made in this way is called AS-H.

Step 5: The AS-H half-cell is coated with an LSM cathode layer with a thickness of 40 μm on the YSZ layer by silk screen technology to form an entire cell, which is referred to as AS-WC. Furthermore, AS-WC is sintered in a high-temperature furnace. (1200 ° C / 3 hrs), the rate of temperature increase / decrease is 1 ° C / min, and the SOFC-MEA is completed as AS-CI (see Figure 10 for details). This is the completed anode-supported battery (or called ASC type SOFC-MEA). The electrical export density of ASC-I increases to 32 mW / cm ² when measured with a simple current system (measurement area is πcm ² and temperature is 900 ° C). Also, when measured at 4 X 4 cm ² , its power export density exceeds 350 mW / cm ² (temperature 800 ° C) (the original MEA is not an optimized product).

1 is a schematic view of a highly consistent solid oxide fuel cell membrane electrode assembly of the present invention and a method for producing the same. Continued 1 is a schematic view of a “Vacuum Hot Press System (VHPS)” in a method according to the present invention. FIG. 2 is a structural diagram and a substantial view of an anode supported cell (ASC for short) of a planar solid oxide fuel cell (Planar SOFC). It is a slurry formulation for manufacture of the SOFC-MEA electrode substrate concerning this invention, and a preparation method figure. It is an entity figure of the slurry for manufacture of a highly conformity electrode substrate green sheet. It is an entity diagram of a highly consistent electrode substrate green sheet. It is an entity diagram of a highly consistent electrode substrate green substrate. It is an entity diagram of a highly consistent electrode substrate. It is a microstructure and characteristic diagram of a highly consistent electrode substrate. It is the result figure of the entity figure of SOFC-MEA (battery cell) manufactured based on the high consistency electrode substrate, and the electrical property measurement.

Claims (15)

1. A method for producing a membrane electrode assembly (MEA-SOFC) for a solid oxide fuel cell, comprising:
A. A slurry production process for producing an electrode substrate green sheet; It consists of the manufacturing process of electrode green sheet substrate and electrode ceramic substrate,
A. The slurry manufacturing process for manufacturing the electrode substrate green sheet is as follows:
(a) Grind ceramic powder, Ni + 8YSZ as anode substrate material, and 8YSZ as electrolyte material to make the powder particle size uniform,
(b) The above powder is co-sintered in a high-temperature oven, added with a pore-forming agent at room temperature, and ground and homogenized to obtain a dry powder.
(c) MEK and EtOH as organic solvents for dissolving the electrolyte material, and TEA as a dispersant are mixed and ground with a ball mill to obtain a uniform liquid phase,
(d) Add the dry powder of (b) to the liquid phase and grind to make a slurry in which the powder is uniformly dispersed in the liquid phase,
(e) Add DBP and PEG as plasticizers and PVB as a bonding agent to the above slurry, grind and homogenize,
(f) Furthermore, a small amount of the bonding agent and plasticizer in the above step is added to finely adjust the viscosity to be suitable for the sheet formation in the subsequent process,
(g) forming a green sheet from the slurry by a sheet forming machine,
(h) A green sheet that is adjusted in size with respect to the above sheet or laminated as necessary to adjust the thickness. The method of manufacturing the electrolyte or electrode ceramic substrate is as follows:
(i) The above green sheet is heated in a mold by a vacuum hot pressure sintering system (VHPS) in a vacuum of 1 × 10 ⁻³ torr or less under a heat pressure (500 ° C. or less and a maximum pressure of 1,152 MPa (1.68 × 10 ⁵ psi) processing to produce high density green sheets (HDGS)
(j) “Highly Consistent Green Sheet” whose structure has been reinforced by “A Novel Synergistic Process” which alternately performs the process of laminating the above high-density green sheets (HDGS) and the process of vacuum hot-pressure sintering (HIGS) "
(k) The above “Highly Consistent Green Sheet (HIGS)” is sandwiched and fixed by a ceramic substrate, calcined to remove the organic solvent and pore former as the first step, and raised in temperature as the second step. HICS (High Integrity Ceramic Substrate) is sintered at 1700 ° C or higher and densified.
(l) A film-forming silk screen (Screen)
Printing, Sputtering Coating, Spin Coating, Plasma Spraying, Electrolyte Layer (if HICS is an Anode Ceramic Substrate) or Electrode Layer (if HICS is an Electrolytic Ceramic Substrate) Applied and sintered in a high-temperature furnace to make a SOFC-MEA half-cell (HC: Half
Cell),
(m) Applying a cathode layer of LSM or LSCF on the electrolyte layer to the above half-cell (HC) by silk screen, sputtering, spin coating, plasma spray, or slurry spray of thin film fabrication technology, Sintered in a high-temperature furnace to form a highly compatible solid oxide fuel cell membrane electrode assembly (battery cell) (SOFC-MEA (Unit Cell))
A method for producing a membrane electrode assembly for a solid oxide fuel cell, comprising each step. NiO + 8YSZ is 50 to 86 wt% as the anode substrate material in the step (a), and 8YSZ is 50 to 86 wt% as the electrolyte material, and NiO is 35 to 65 wt% of the total weight of NiO + 8YSZ,
As a pore-forming agent in the step (b), graphite is 0.1 to 10 wt% with respect to the anode material,
MEK as the organic solvent in step (c) is 12 to 22 wt%, EtOH is 5 to 9 wt%, and TEA is 1 to 2 wt% as the dispersant,
0.5 to 2.0 wt% DBP as a plasticizer in step (e), 0.5 to 2.0 wt% PEG, and 3 to 6 wt% PVB as a bonding material,
2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein: The grinding in step a is performed by a ball mill equipped with a zirconium oxide mill ball, the grinding time is 24 to 168 hours, and the average particle size of the ground powder is 300 to 500 nm. 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1. The temperature and time of the co-sintering in the step b are 1200-1600 ° C. and 2-8 hours, respectively, the second grinding is 24 hours or more, the average particle size is 300-500 nm, 2. The membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein (nano or micro grade) graphite powder is used, and a target porosity of the ceramic substrate is adjusted by an amount of the powder added. Production method. 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein the grinding time of the ball mill in step c is 24 hours. 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein the third grinding time in the step d is 48 hours. 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein the fourth grinding time in the step e is 48 to 72 hours. 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein the slurry viscosity in the step f is 150 to 1500 cP. 2. The method of manufacturing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein the green sheet in step g has a width of 18 to 30 cm and a thickness of 10 to 300 μm. The shape of the green sheet in the step h is circular or square, the size is 5 × 5 cm ² to 15 × 15 cm ² , and the operation temperature and pressure of the laminating process are 50 to 100 ° C. and 14 MPa to 34 MPa (2000 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein the formed green sheet has a thickness of 600 to 1200 μm. The operating temperature and pressure of the vacuum hot-pressure sintering process of step h are <500 ° C. and 1,152 MPa (1.68 × 10 ⁵ psi), respectively, and the degree of vacuum is 1.0 × 10 ⁻³ torr. 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1. 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein the second stacking operation in step j is 2 or more. The temperature condition of the sintering process of the first stage of the above step k is:
Room temperature → 200 ° C (4Hr) → 450 ° C (2Hr) → 750 ° C (2Hr) → 1250 ° C (6Hr) → room temperature.The temperature conditions for the second stage sintering process are:
2. Room temperature → 1400 ° C. (4Hr) → Room temperature, and the rate of temperature increase / decrease in the sintering process in both stages is 1 ° C./min (however, 3 ° C./min or less is preferable). A process for producing a membrane electrode assembly for a solid oxide fuel cell as described in 1 above. 2. The electrolyte layer of step 1 is 10 μm, the sintering temperature control procedure is room temperature → 1400 ° C./4 hrs → room temperature, and the rate of temperature rise / fall is 3 ° C./min or less. A process for producing a membrane electrode assembly for a solid oxide fuel cell as described in 1 above. The material and thickness of the cathode layer in step m above are LSM / LSCF and 30-50 μm, respectively, and the sintering temperature control procedure is room temperature → 1200 ° C./3 hrs → room temperature, and the rate of temperature rise / fall is 3 ° C. / 2. The method for producing a membrane electrode assembly for a solid oxide fuel cell according to claim 1, wherein the membrane electrode assembly is min or less .

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