TWI441384B - A novel process for fabrication of a sputter deposited fully dense electrolyte layer embedded in a high performance membrane electrolyte assembly (mea) (unit cell) of solid oxide fuel cell - Google Patents

Description

Process for producing a fully dense sputtered electrolyte layer in a high performance solid oxide fuel cell membrane electrode assembly element (cell)

The present invention relates to a manufacturing technique for an electrolyte layer of a solid oxide fuel cell, and more particularly to a film forming process, namely, Magnetron Sputter, combined with a fuel cell membrane electrode assembly (Membrane Electrode Assembly) , MEA) production procedures, such as Tape casting, Lamination, Vacuum Hot Pressing, Screen printing, Spin coating, or Plasma spraying (Plasma spray coating), etc., and the optimization of sintering technology to produce a fully dense electrolyte technology to develop a gas-tight electrolyte layer of a solid oxide fuel cell.

As oil prices rise and environmental awareness rises, renewable energy technology has become one of the most important development technologies of this century. Solid oxide fuel cells are power generation systems with high efficiency, low pollution and diversified energy, and are characterized by simple material composition, modular structure and sustainable and stable power generation. They are the most promising power generation systems.

The battery of the electrolyte supporting substrate (Electrolyte Supported Cell: ESC) operates at a temperature between 800 and 1000 °C. The thickness of the electrolyte layer substrate is about 150 to 300 μm. It belongs to SOFC-MEA of the first generation. The anode support substrate unit (Anode Supported Cell: ASC) has an operating temperature of 650-800 ° C and an electrolyte layer thickness of about 10 μm, belonging to the second generation SOFC-MEA. (NiO+8YSZ) is the anode material of ASC/ESC. The cathode material is mainly LSM (镧锶 manganese oxide) and LSCF (samarium cobalt oxide) with a thickness between 30 and 60 μm. New electrolyte materials and cathode materials are being researched and developed in various research labs around the world. It is expected to develop new materials and reduce the operating temperature of SOFC-MEA to 500~700 °C. At that time, the stack components of SOFC stacks such as connecting plates (Inter-connector) ), the metal material can be used to replace the ceramic material, which is not only easy to manufacture, but also increases in mechanical/stability/endurance, and lowers the overall cost. This technology development, in the field of universities and national research, focuses on material research and development, and hopes to invent advanced materials to reduce impedance, increase the conductance/conductivity, and increase the power generation of SOFC.

The main object of the present invention is to develop a manufacturing process for a solid oxide fuel cell having a fully dense electrolyte layer.

According to the above object of the present invention, a magnetron sputtering process is mainly combined with a Membrane Electrode Assembly (MEA) manufacturing process, such as tape casting and lamination. , vacuum thermocompression (Vacuum Hot Pressing), screen printing, spin coating or plasma spray coating, combined with the design and control of sintering conditions, can successfully prepare fully dense electrolyte Process. The magnetron sputtering process referred to in the present invention comprises (1) a radio frequency magnetron sputtering method for sputtering an oxide target and (2) a reactive magnetron sputtering method for a sputtering metal alloy target, including a direct current and a radio frequency. . Taking an anode supported substrate unit (ASC) as an example, the program of the present invention prepares an electrolyte film by magnetron sputtering. The cathode layer is coated on the electrolyte surface of the half-cell, so that an anode-supported solid oxide fuel cell having a fully dense electrolyte layer can be developed. Preferred embodiments of the invention are described below.

The present invention is a flat type for producing a layer having a "Fully dense"/Zero gas leakage rate or an air tight (e.g., 8YSZ/GDC/YDC/LSGM, etc.) layer. Procedure for solid oxide fuel cell membrane electrode assembly (SOFC-MEA) (ie, unit cell). The implementation method of this program is as follows:

Step 1: On the electrode substrate (Electrode Substrate) of the flat type SOFC-MEA, an electrolyte film (5-15 μm) is constructed on the electrode substrate by a magnetron sputtering method (Magnetron Sputter), and the SOFC is formed. Half cell (Half cell), and sintering at 1200 ° C ~ 1600 ° C (first choice of 1400 ° C) for several hours (more than 3 hours), to get the first half of the battery, the electrolyte can be YSZ, GDC, YDC, SDC, LSGM. Electron microscopy (SEM) was used as a micro-structure analysis of the half-cell to confirm that the electrolyte layer had reached the open state and the degree of full density of the open-pore free.

Step 2: On the electrolyte layer of the half-cell, a porous (Porous) cathode layer (usually LSM or LSCF, etc.) is built by a screen printing process, and then calcined at 1200 ° C for about 3 hours, that is, The production of SOFC-MEA can be completed. The SOFC-MEA is thus made with high operational performance, durability and stability. It can be verified by the performance test of SOFC-MEA. The above process for preparing a fully dense/air-tight electrolysis The program of the SOFC-MEA of the quality layer. A simple flow chart of steps 1 and 2 above is shown in FIG.

The following describes an embodiment of the present invention in detail:

Example 1

Step 1: Procedure for making a solid oxide fuel cell composite component (SOFC-MEA) unit cell (Unit Cell) with a fully dense/airtight electrolyte (8YSZ/GDC/LSGM) layer. The anode substrate of the MEA is composed of 50 wt% NiO+50 wt% 8YSZ and a specific amount of Pore former graphite (Graphite), and is formed by a blade forming process, a thin strip lamination and a vacuum pressing procedure. It has strong mechanical strength, a thickness of about 1000 μm, and a size of 5×5 cm ² to 12×12 cm ² .

Step 2: Electrolyte film production method, RF magnetron sputtering (target material is 8YSZ oxide target) and DC magnetron sputtering (target material is Zr _x Y _1-x alloy target, 80<x<100wt.%) The electrolyte material is deposited on the electrode substrate to a thickness of 5 to 10 μm to form a half cell of the SOFC, and is carried out for several hours between 1200 ° C and 1600 ° C (preferred at 1400 ° C) ( After sintering for more than 3 hours, the first stage half-battery was obtained, and the microstructure analysis of the half-cell was performed by SEM, and it was confirmed that the electrolyte layer had reached the micro-structure state of the open-pore free, as shown in the figure. As shown in the second, the thickness of the electrolyte layer is about 5/10 μm, and a completely dense structure has been formed. Airtight performance can be achieved to meet the necessary requirements of the SOFC-MEA electrolyte layer. Only a few holes remain, which are closed pores, which do not affect the airtightness of the electrolyte layer and the permeability of the gas.

Step 3: In order to completely confirm the electrolyte gas tightness performance, the gas permeability of the half-cell obtained in the step 2 can be measured. When the gas permeability is below 1×10 ^-6 l/cm ² /sec, the electrolyte layer can be considered as Fully dense target.

Step 4: The fully dense half-cell structure confirmed in step 3 is constructed by a screen printing process to construct a porous cathode layer LSM material. By performing a sintering process at 1100 ° C / 3 hrs, a high operating performance SOFC-MEA (Unit cell) can be produced. The cross-sectional microstructure of the unit full cell is shown in Figure 3 as the SEM analysis. The prepared SOFC-MEA was tested for electrical performance. The power generation test temperature was 700/750/800 ° C, the test atmosphere was 100% H ₂ /O ₂ , and the flow rate was 200/300/400 cc/min. The overall test time can be as long as 120 hours or more without the performance weakening. The test process is shown in Figure 4. The open circuit voltage (OCV) of the unit cell is close to the theoretical value, up to 1.06V, and the power density at 800°C is up to 515mW/cm ² (as shown in Figure 5). It is prepared by sputtering. The obtained electrolyte layer is dense and stable, and the obtained unit cell has excellent power generation performance. The above results prove that the excellence of the production process, the innovation and the key to the technology, have indeed met the requirements of the invention patent application.提出 Submit a patent application in accordance with the law.

However, the above-described processes are merely examples of the present invention, and the scope of the present invention and the simple equivalent changes and modifications of the contents of the invention should be The scope of coverage of the patents of the present invention.

The first figure is a schematic diagram of a brief implementation of the procedure of the present invention.

The second figure is a SEM microstructural analysis of the cross-sectional structure of a solid oxide fuel cell with thin film technology and sintering conditions: (a) half-cell structure diagram of the oxide target preparation electrolyte, and (b) oxide target preparation electrolyte The surface morphology of the electrolyte layer, (c) the half-cell structure diagram of the electrolyte target reactive sputtering to prepare the electrolyte, and (d) the surface morphology of the electrolyte layer prepared by reactive sputtering of the alloy target.

The third figure is a full cell structure diagram of a solid oxide fuel cell in which an oxide target is prepared for an electrolyte.

The fourth figure is a diagram showing the electrical performance test procedure of the solid oxide fuel cell for preparing an electrolyte from an oxide target.

The fifth picture shows the electrical performance test results of solid oxide fuel cells. JVP diagram (current density / voltage / power generation density): (a) test results of unit cells at different temperatures (700/750/800 ° C), (b The cell batteries were tested at different H ₂ /O ₂ flow rates (100% H ₂ /O ₂ flow rates: 200/300/400 cc/min).

Claims (8)

A method for preparing a flat-type solid oxide fuel cell membrane electrode assembly element (SOFC-MEA) of a fully dense electrolyte layer, mainly based on a magnetron sputtering method of a film manufacturing process, and a tape casting method (Tape casting) Screen printing, spin coating or plasma spray coating is used as a film making program, and combined with the control technology of sintering conditions. The production process includes at least the following steps: a. preparing an anode substrate of the SOFC; b. preparing an electrolyte layer by a magnetron sputtering process on the anode substrate to form a SOFC half cell; and the magnetron sputtering process comprises (1) RF magnetron sputtering of the sputtering oxide target Method and (2) reactive magnetron sputtering method for sputtering metal alloy target; c. anode/electrolyte half-cell structure is sintered at a high temperature to obtain a half-cell substrate, and the sintering temperature is above 1400 ° C for at least 3 hours. Calcination procedure, and the results of the gas permeability test and electron microscopy (SEM) microstructure observation to confirm the density of the electrolyte layer, if the density is completely dense, that is, the gas permeability is less than 1 × 10 ^-6 L/cm ² /sec, the following step d can be performed; d. The half cell (HC-fd for short) having a completely dense electrolyte layer is constructed on the electrolyte layer by a screen printing process, and 1100 ° C is performed. A sintering process of about 3 hours is completed to complete the fabrication of the all-cell battery, and electrical operation tests and electrical power density measurements are performed on the completed unit cells to identify the characteristics of the unit cells. A method for preparing a flat-type solid oxide fuel cell membrane electrode assembly element (SOFC-MEA) according to the full dense electrolyte layer according to claim 1, wherein the electrolyte The material may be Yttria-stabilized Zirconia (hereinafter referred to as YSZ), Gadolinia-doped Ceria (GDC), and Lanthanum Strontium Gallium Magnetite (hereinafter referred to as LSGM), such materials as Samaria-doped Ceria (SDC) and Yttria-doped Ceria (YDC). The method for preparing a flat-type solid oxide fuel cell membrane electrode assembly element (SOFC-MEA) according to the full density electrolyte layer of claim 1, wherein the anode substrate of the SOFC prepared in step a is made of YSZ +NiO and YSZ, GDC, LSGM, SDC, YDC; wherein the weight percentage of the electrolyte YSZ and the anode catalytic material NiO may be 50 wt.%. The method for preparing a flat solid oxide fuel cell membrane electrode assembly element (SOFC-MEA) according to the full dense electrolyte layer of claim 1, wherein the magnetron sputtering method of step b is performed on the anode substrate A dual-target co-sputter method for constructing an electrolyte layer, which is a process for fabricating an SOFC electrolyte layer or an anode layer, can be a sputtering, screen printing, spin coating, and plasma spraying technique. A method for preparing a flat-type solid oxide fuel cell membrane electrode assembly element (SOFC-MEA) according to the full density electrolyte layer of claim 1, wherein the magnetron sputtering method of step b (1) sputtering oxide The RF magnetron sputtering method of the target, the oxide target can be YSZ+NiO and YSZ, GDC, LSGM, SDC, YDC; (2) reactive magnetic sputtering method of sputtering metal alloy target, The metal alloy target may be Zr _x -Y _1-x (80<x<100wt.%), LSGM, respectively. A method for preparing a flat-type solid oxide fuel cell membrane electrode assembly element (SOFC-MEA) according to the full dense electrolyte layer according to claim 1, wherein step b constructs an electrolyte layer on the anode substrate, and the SOFC electrolyte layer is formed The program can be used for sputtering, screen printing, spin coating, and plasma spraying. The method for preparing a flat solid oxide fuel cell membrane electrode assembly element (SOFC-MEA) according to the full dense electrolyte layer of claim 1, wherein the half-cell sintering procedure of step c can be 1400 ° C and 3 Hrs, sintering The equipment can be a high temperature furnace that passes air. The method for preparing a flat-type solid oxide fuel cell membrane electrode assembly element (SOFC-MEA) according to the full dense electrolyte layer according to claim 1, wherein the step d is to press the HC-fd into a cathode material by a screen printing process. Built on the electrolyte layer, other sputtering, plasma spraying, spin coating procedures are included, the sintering procedure can be 1100 ° C / 3 hours, the cathode material can be LSM (镧锶 manganese oxide), LSCF (镧锶 cobalt For materials such as iron oxide), the cathode layer may have a thickness of 30 to 60 μm.