JP2009266765A - Method for manufacturing electrolyte layer of high performance solid oxide fuel cell membrane-electrode assembly (sofc-mea) by sputtering method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell membrane-electrode assembly (battery cell) having a completely dense/airtight electrolyte layer. <P>SOLUTION: A thin membrane electrolyte layer is formed by a magnetron sputtering method on an anode electrode support substrate wherein a designated thickness is formed by laminating a green tape formed by a tape casting method, the thin membrane electrolyte layer becomes a half cell by sintering, and a cathode electrode layer is formed by a silk screen printing method on this membrane electrolyte layer and it is sintered in order to form a battery cell. Here, a gas permeable rate of the electrolyte layer is 1×10<SP>-6</SP>L/cm<SP>2</SP>/sec or below, an open circuit voltage of the whole battery is 1.0V or more, and electric power density at a power generation test is 500mW/cm<SP>2</SP>or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a solid oxide fuel cell electrolyte layer, and more particularly to a method for producing a thin film, and includes a single-target sputter and a multi-target co-sputter. The reactive magnetron sputtering method (Magnetron Sputtering), which is classified into two types of power supply, direct current and radio frequency, tape casting, laminating, Optimized together with the manufacturing process of fuel cell membrane assembly (MEA) such as screen printing, spin coating, and plasma spray coating. It is an object of the present invention to manufacture a completely dense electrolyte layer by using the sintered technique and to manufacture an airtight electrolyte layer of a solid oxide fuel cell.

  Renewable energy technology has become one of the most important development technologies of this century as the price of crude oil rises and the consciousness of environmental protection increases. A solid oxide fuel cell is an energy power generation system with the features of high efficiency, low pollution and energy diversification. The material composition is simple, and the modularization of the structure can provide sustainable and stable power generation. Because of this feature, it will be a power generation system with the most potential for development.

The operating temperature of an Electrolyte Supported Cell (abbreviated as ESC) belonging to the first generation SOFC-MEA is 800 to 1000 ° C., and the thickness of the electrolyte substrate is 150 to 300 μm.
The operating temperature of the anode supported cell battery cell (Anode Supported Cell: abbreviated as ASC) belonging to the second generation SOFC-MEA is 650 to 800 ° C., and the thickness of the electrolyte substrate is 10 μm.
In these ASC / ESC, the anode material is (NiO + 8YSZ (yttrium stabilized zirconia)), the main materials of the cathode are LSM and LSCF, and the thickness thereof is 30-60 μm. New electrolyte materials and cathode materials are currently being developed in research institutes and laboratories around the world. By introducing new materials, the operating temperature of SOFC-MEA will be further reduced to 500-700 ° C. Is desired.
At that time, metal materials can be used instead of ceramic materials as assembly materials for SOFC battery stacks, for example, inter-connectors, etc., making it easy to manufacture and its mechanical strength / stability / Durability is also improved, and cost reduction of the entire SOFC can be expected. These technological developments are focused on materials research and development in universities and national laboratories and research institutes, and SOFC by reducing resistance and improving ion conduction / electric conductivity by developing materials. The power generation capacity is expected to improve.
JP 2005-149797 A JP-A-5-174850

  The present invention provides a method of manufacturing a solid oxide fuel cell having a fully dense SOFC-MEA electrolyte layer. The SOFC-MEA produced in this way has high operability, durability and stability, and can be verified by a battery cell electrical performance test (Performance test of SOFC-MEA).

  In order to achieve the above goal, the tape casting method and the silk screen printing method of the film formation method related to the manufacture of the fuel cell membrane electrode assembly (MEA), centering on the magnetron sputtering method ( Screen printing, spin coating, plasma spray coating, etc. and laminating methods for laminating films are used in combination with sintering technology design and control. / Provides a manufacturing method for manufacturing an airtight electrolyte layer (material is selected from 8YSZ, GDC (Gd doped ceria), LSGM (strontium and magnesium doped lanthana gallat), etc.).

The magnetron sputtering method shown in the present invention includes (1) RF magnetron sputtering method (Radio frequency magnetron sputtering) for sputtering an oxide target, and (2) two types of direct current and radio frequency. There are two types of sputtering of a metal alloy target by the reactive magnetron sputtering method. The oxide target materials are YSZ + NiO, GDC + NiO, LSGM + NiO, SDC + NiO, YDC + NiO, YSZ, GDC, LSGM, SDC, YDC, and the metal alloy target materials are Zr _x -Y _1-x , Zr _x -Sc _{1-x, Ce x -Gd 1} -x, Ce x -Sm 1-x, Ce x -Y 1-x (80 <x <100 wt.%), a LSGM.
For example, in the case of an anode supported cell battery cell (ASC), the present invention forms a thin-cell electrolyte on the anode substrate by a magnetron sputtering method, and a half-cell structure is obtained through a high-temperature sintering process. . Further, a cathode layer is formed in a half-cell structure by a silk screen printing method, and an anode-supported solid oxide fuel cell having a completely dense electrolyte layer is completed.

  The present invention relates to a flat solid oxide fuel cell membrane electrode assembly (SOFC-MEA) having an electrolyte layer with full dense and zero gas leakage rate or air tight. That is, it is a method of manufacturing a battery cell (Unit cell). The electrolyte material is selected from 8YSZ, GDC, YDC, LSGM, etc. A method for producing a flat solid oxide fuel cell membrane electrode assembly having a completely dense electrolyte layer according to the present invention will be described below.

  Step 1: An electrolyte thin film is formed on an electrode substrate (Electrode Substrate) of a flat plate SOFC-MEA by a magnetron sputtering method. A 5-15 μm electrolyte thin film is formed on the electrode substrate to form a SOFC half cell, and sintering is performed at 1200 ° C. to 1600 ° C. for several hours (over 3 hours). A battery is obtained. The electrolyte material at this stage is selected from YSZ, GDC, YDC, SmDC, and LSGM. Analyze the micro-structure of the half-cell with a scanning electron microscope (SEM) to confirm that an open-pore free microstructure and a fully dense state have been achieved.

  Step 2: A porous cathode layer is constructed on the half-cell electrolyte layer by silk screen printing. The material of the cathode layer is generally LSM or LSCF. Perform calcination for 3 hours at 1200 ℃ to complete SOFC-MEA.

  The present invention will be described more specifically with typical examples. The process of Step 1 and Step 2 of the manufacturing method is shown in FIG. These are merely illustrative examples, and the present invention is not limited thereto.

〔Example〕
Step 1: Full dense and air tight electrolyte (material is 8YSZ / GDC / LSGM, etc.) Plate type solid oxide fuel cell membrane electrode assembly (SOFC-MEA) In order to manufacture a unit cell, the basic material is first composed of 50 wt% NiO + 50 wt% 8YSZ and a specific amount of pore former (Pore former) and graphite. It is formed into a size of 5 × 5 cm ² to 12 × 12 cm ² by a casting method and laminated to a thickness of 1000 μm by lamination.

Step 2: Deposit electrolyte material on the electrode substrate by RF magnetron sputtering method (target material is 8YSZ oxide) or DC magnetron sputtering method (target material is Zr _x Y _1-x alloy) Then, form a SOFC half cell (Half cell) with a thickness of 5 to 10 μm, and sinter for several hours (3 hours or more) at 1200 ° C to 1600 ° C (1400 ° C is optimal). Get a battery. This half-cell is analyzed for microstructure by SEM (scanning electron microscope), and it is confirmed that the electrolyte layer has a non-porous (open-pore free) microstructure. As shown in FIG. 2, the thickness of the electrolyte layer is about 5 to 10 μm and has a completely dense structure, which is airtight and satisfies the requirements for the SOFC-MEA electrolyte layer. The very few obstructive pores that remain do not affect the gas permeability.

Step 3: Measure the gas permeability of the half-cell obtained in Step 2 to confirm that the electrolyte's hermetic performance is complete. If the gas permeability is 1 × 10 ⁻⁶ l / cm ² / sec or less, the electrolyte is considered to be completely dense.

Step 4: Form a porous cathode layer with LSM material by silk screen printing on the fully dense half-cell structure confirmed in Step 3 and sinter at 1100 ° C for 3 hours. Obtain SOFC-MEA (Unit cell). FIG. 3 shows the result of SEM analysis of the cross section of the microstructure of the battery cell. The electrical performance test of the completed SOFC-MEA was conducted.
The temperature of the power generation test was 700/750/800 ° C., the test gas was 100% H ₂ / O ₂ , and the flow rate was 200/300/400 cc / min. During the test, power lasted over 120 hours without decay. The test process is shown in FIG. The open circuit voltage (OCV) of the battery cell is close to the theoretical value, and the maximum value reaches 1.06 V. The power density at 800 ° C reaches a maximum of 515 mW / cm ² (shown in Figure 5). From these experimental results, it has been clarified that the electrolyte layer manufactured by the sputtering method has denseness, the operation is stable, and the power generation performance of the battery cell is excellent.

The simplified process figure of the manufacturing method of this invention. Microstructure analysis diagram of SEM image of cross-sectional structure of solid oxide fuel cell with thin film technology adapted to sintering conditions: (a) Half-cell structure diagram of electrolyte fabricated with oxide target, (b) Surface pattern of the electrolyte layer where the electrolyte was fabricated with an oxide target, (c) Half-cell structure diagram of the electrolyte layer produced by reactive sputtering of the alloy target, (d) Electrolyte by reactive sputtering of the alloy target The surface state of the electrolyte layer that produced the layer. The whole battery structure figure of the solid oxide form fuel cell which produced the electrolyte layer with the oxide target. The electrical performance measurement figure of all the cells of the solid oxide fuel cell which produced the electrolyte layer with the oxide target (target). JVP diagram of electrical performance measurement results of solid oxide fuel cell (showing the relationship between current density / voltage / power density) (a) shows the results of measuring battery cells at different temperatures (700/750/800 ° C) ( b) Results of measuring battery cells at different H ₂ / O ₂ flow rates (100% H ₂ / O ₂ flow rate is 200/300/400 cc / min)

Claims (9)

A method for producing a flat plate solid oxide fuel cell membrane electrode assembly (SOFC-MEA), comprising:
(a) A SOFC anode electrode substrate is formed by a tape casting method or the like.
(b) forming an electrolyte thin film layer on the electrode substrate by a radio frequency (RF) magnetron sputtering method for sputtering an oxide target or a reactive magnetron sputtering method for sputtering a metal alloy target;
(c) The anode / electrolyte half-cell structure produced by the above process was sintered at 1400 ° C. for 6 hours at a high temperature, and the gas permeability of the electrolyte layer was 1 × 10 ⁻⁶ L / cm ² / sec or less. Get a half-cell board,
(d) On the electrolyte layer of a half-cell (abbreviated HC-fd) having an electrolyte layer obtained by the above process, a silk screen printing method, a spin coating method, or a plasma spray coating method (Plasma spray coating method) A cathode material layer is formed by spray coating), and sintering is performed at 1000 ° C. for 3 hours to obtain an entire battery.
A process for producing a plate-type solid oxide fuel cell membrane electrode assembly (SOFC-MEA), characterized by comprising steps.   2. The plate type solid oxide fuel cell membrane electrode assembly according to claim 1, wherein the electrolyte material is YSZ, GDC, LSGM, SDC (Sm doped ceria), or YDC (Y doped ceria). (SOFC-MEA) manufacturing method. In the method for producing an electrolyte layer of the flat plate type solid oxide fuel cell membrane electrode assembly (SOFC-MEA),
The anode substrate material of the above step a is YSZ + NiO, GDC + NiO, LSGM + NiO, SDC + NiO, or YDC + NiO,
The material of the electrolyte substrate is YSZ (yttrium stabilized zirconia), GDC (Gd doped ceria), LSGM (strontium and magnesium doped lanthana gallat), SDC (Sm doped ceria), or YDC (Y doped ceria). The percentage of the weight ratio of, for example, YSZ) to the electrode catalyst material NiO is 30 to 65%, and the production of a plate type solid oxide fuel cell membrane electrode assembly (SOFC-MEA) according to claim 1 Method. The magnetron sputtering method of step b above is
Multi-target sputtering method (multi-gun co-sputter) in which an electrolyte layer or functional interface layer is laminated on an anode electrode substrate, or multi-target sputtering method (multi-target sputtering method in which an electrolyte layer or functional interface layer is laminated on an electrolyte substrate) The method of forming an electrode layer on a SOFC electrolyte layer by using a -gun co-sputter) is based on a sputtering method, a silk screen printing method, a spin coating method, or a plasma spray coating method. A method for producing a plate-type solid oxide fuel cell membrane electrode assembly (SOFC-MEA). The oxide target materials used in the radio frequency magnetron sputtering method of the oxide target method in Step b above are YSZ + NiO, GDC + NiO, LSGM + NiO, SDC + NiO, YDC + NiO, YSZ, GDC, LSGM, SDC, YDC. ,
Reactive magnetron sputtering to sputter metal alloy targets The metal alloy target materials used in the sputtering method are Zr _x -Y _1-x , Zr _x -Sc _1-x , Ce _x -Gd _1-x , Ce _x -Sm _{1- x, Ce x -Y 1-x} (80 <x <100 wt.%), a flat plate type solid oxide fuel cell membrane electrode assembly according to claim 1, characterized in that the LSGM (SOFC-MEA) Manufacturing method. In the method for producing an electrolyte layer of the high performance solid oxide fuel cell membrane electrode assembly (SOFC-MEA),
The electrolyte layer of step b is manufactured by RF magnetron sputtering using 8YSZ as the target material or DC magnetron sputtering using Zr _x Y _1-x alloy as the target material. 2. The method for producing a flat plate type solid oxide fuel cell membrane electrode assembly (SOFC-MEA) according to claim 1, wherein the deposition is performed on an electrode substrate.   2. The flat plate mold according to claim 1, wherein the half-cell sintering step of step c is performed at 1400 [deg.] C. for 6 hours, and the rate of temperature increase / decrease is 1-5 [deg.] C./min in an air atmosphere. A method for producing a solid oxide fuel cell membrane electrode assembly (SOFC-MEA).   The method of laminating the cathode layer on the HC-fd electrolyte layer in step d above is a silk screen printing method, sputtering method, spin coating method, or plasma spray coating method, using LSM or LSCF as the cathode material. The thickness is 30 to 50 μm, the sintering condition is sintering at 1100 ° C. for 3 hours, and the rate of change in the rate of increase and decrease of the sintering temperature is 1 to 3 ° C./min. A method for producing a flat plate solid oxide fuel cell membrane electrode assembly (SOFC-MEA) as described.   The flat solid according to claim 1, wherein in step c, the microstructure of the half-cell is analyzed by SEM to confirm the denseness of the electrolyte layer, and the gas permeability is determined by a gas permeability measuring device. A process for producing an oxide fuel cell membrane electrode assembly (SOFC-MEA).