WO2020017796A1 - Method for manufacturing solid oxide fuel cell for preventing degradation under negative cell voltage - Google Patents

Method for manufacturing solid oxide fuel cell for preventing degradation under negative cell voltage Download PDF

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WO2020017796A1
WO2020017796A1 PCT/KR2019/008198 KR2019008198W WO2020017796A1 WO 2020017796 A1 WO2020017796 A1 WO 2020017796A1 KR 2019008198 W KR2019008198 W KR 2019008198W WO 2020017796 A1 WO2020017796 A1 WO 2020017796A1
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layer
solid oxide
oxide fuel
fuel cell
electrolyte
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Korean (ko)
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임형태
손민지
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창원대학교 산학협력단
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8605—Porous electrodes
    • H01M4/8621—Porous electrodes containing only metallic or ceramic material, e.g. made by sintering or sputtering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8636—Inert electrodes with catalytic activity, e.g. for fuel cells with a gradient in another property than porosity
    • H01M4/8642—Gradient in composition
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
    • H01M4/8882—Heat treatment, e.g. drying, baking
    • H01M4/8885—Sintering or firing
    • H01M4/8889—Cosintering or cofiring of a catalytic active layer with another type of layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9016—Oxides, hydroxides or oxygenated metallic salts
    • H01M4/9025—Oxides specially used in fuel cell operating at high temperature, e.g. SOFC
    • H01M4/9033—Complex oxides, optionally doped, of the type M1MeO3, M1 being an alkaline earth metal or a rare earth, Me being a metal, e.g. perovskites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/023—Porous and characterised by the material
    • H01M8/0236—Glass; Ceramics; Cermets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M8/1213—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the electrode/electrolyte combination or the supporting material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M8/1213—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the electrode/electrolyte combination or the supporting material
    • H01M8/1226—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the electrode/electrolyte combination or the supporting material characterised by the supporting layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M8/124—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M8/124—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte
    • H01M8/1246—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides
    • H01M8/1253—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte characterised by the process of manufacturing or by the material of the electrolyte the electrolyte consisting of oxides the electrolyte containing zirconium oxide
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/24—Grouping of fuel cells, e.g. stacking of fuel cells
    • H01M8/241—Grouping of fuel cells, e.g. stacking of fuel cells with solid or matrix-supported electrolytes
    • H01M8/2425—High-temperature cells with solid electrolytes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M2008/1293—Fuel cells with solid oxide electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention is (i) Ministry of Trade, Industry and Energy's national research and development project (project unique number: 20163030031850, business name: energy technology development project, research project name: development of high reliability SOFC stack manufacturing technology for distributed generation, research management professional organization: energy technology Assessment Agency, Organizer: Mico Corporation, Research Period: 2017.10.01 ⁇ 2018.07.30) and (ii) National R & D project implemented by Ministry of Science and Technology Information and Communication (Project number: 2017M1A2A2045018, Project name: climate change technology development project, Project Title: Development of in-situ diagnostic technology for optimizing SOFC stack design, Research and management agency: Korea Research Foundation, Organized by Changwon National University Industry-University Cooperation Group, Research Period: 2018.05.01 ⁇ 2019.02.28) As a result of Changwon University,
  • the present invention relates to a method for manufacturing a solid oxide fuel cell, and more particularly, to a method for manufacturing a solid oxide fuel cell including an electrolyte layer having a structure capable of preventing degradation of an SOFC cell stack under a negative cell voltage. It is about.
  • the electromotive force of a fuel cell is about 1V maximum per unit cell, and stacking several cells in series is necessary to obtain a desired output.
  • the low performing cell operates at a negative cell voltage above the threshold current value, causing physical destruction due to rapid deterioration, thereby stopping the entire stack operation. (FIG. 1).
  • This phenomenon is a phenomenon commonly occurring in electrochemical devices connected in series. In order to stabilize and commercialize a battery, performance deviation between cells must be minimized.
  • YSZ zirconia
  • the oxygen ion conductivity is different depending on the point of view.
  • pure oxygen ion conductivity has the advantage of high open circuit voltage and therefore high power.
  • pure oxygen ion conductivity no longer serves as an advantage.
  • Korean Patent No. 10-1180182 (a solid oxide fuel cell with excellent peeling resistance) uses a triple layer electrolyte to include a ceria component only in an electrolyte layer close to an anode to impart electronic conductivity, thereby providing leakage current. And deterioration to the reverse voltage was suppressed.
  • a multilayer electrolyte structure has several drawbacks, such as complicated manufacturing process, high resistance due to thick electrolyte, and interfacial resistance between layers.
  • the technical problem to be solved by the present invention is a solid oxide that can effectively prevent the separation between the negative electrode layer and the electrolyte layer in a reverse voltage situation without generating problems such as the complexity and resistance of the electrolyte layer manufacturing process of the prior art It is to provide a fuel cell manufacturing method.
  • the cell using the YSZ electrolyte not only reduces the voltage per hour, but also the open circuit voltage and power density after operation. After the analysis, it was found that exfoliation was observed at the interface between the anode and the electrolyte.
  • YSZ Yttria-stabilized zirconia
  • the cause of the peeling phenomenon between the negative electrode and the electrolyte interface is due to the high oxygen partial pressure at the negative electrode / electrolyte interface due to the reverse voltage. It is important to reduce the oxygen partial pressure at the interface to prevent the peeling phenomenon.
  • the present invention is a method of not directly adding ceria to the inside of an electrolyte, and forms a negative electrode layer containing ceria having electronic conductivity on one surface during cell manufacturing, and sinters the cell to obtain a high temperature.
  • the present invention (a) an anode layer having a layer containing ceria (CeO 2 ) formed on one surface; An electrolyte layer formed on the layer including ceria and including Yttria-stabilized zirconia (YSZ); And manufacturing a solid oxide fuel cell unit cell stacked in the order of the cathode layer. And (b) sintering the solid oxide fuel cell unit cell, wherein the reverse voltage degradation phenomenon is prevented.
  • the negative electrode layer is an anode functional layer (Anode Functional Layer,) formed on the negative electrode support layer as a layer comprising an anode support (AS) and the ceria AFL).
  • the negative electrode support layer and the negative electrode functional layer may be made of a nickel (Ni) -based material, and further, the negative electrode support layer may include nickel and YSZ, and the negative electrode functional layer may include nickel, YSZ and ceria.
  • the anode layer may include a cathode functional layer (CFL) formed on the electrolyte layer and a cathode collector layer (Current Collector, CC) formed on the anode functional layer.
  • CFL cathode functional layer
  • CC cathode collector layer
  • the positive electrode functional layer may include SSM (Sr-doped LaMnO 3 ) and YSZ
  • the positive electrode current collector layer may include an LSM.
  • step (b) the unit cell prepared in step (a) is sintered, and the cerium ions are diffused into the electrolyte layer from the layer containing ceria provided on the cathode side through sintering.
  • a gradient structure in which the cerium concentration decreases toward the center of the electrolyte layer from the electrolyte layer interface is formed.
  • the sintering conditions in the step (b) is a sintering temperature and time if the inclined structure of a predetermined thickness (but should be smaller than the total thickness of the electrolyte layer) from the cathode layer and the electrolyte layer interface can be formed Is not particularly limited, and may be, for example, 1 to 11 hours at a temperature of 1410 to 1510 °C.
  • a solid oxide fuel cell stack including a plurality of unit cells is provided.
  • a solid oxide fuel cell (SOFC) according to the present invention
  • cerium ions are diffused from the layer containing ceria provided on the cathode side into the electrolyte layer from the cathode / electrolyte layer interface.
  • a solid oxide fuel cell having a gradient anode / electrolyte structure in which cerium concentration decreases toward the center of the electrolyte layer may be manufactured, and the solid oxide fuel cell may locally have only an electrolyte section close to the cathode / electrolyte interface. It has an electron conductivity (N-type) to effectively prevent the negative electrode / electrolyte peeling in the reverse voltage situation, and since only a part of the inside of the electrolyte has an electronic conductivity it can also prevent the leakage current.
  • N-type electron conductivity
  • the cerium ions are diffused into a single layer of an electrolyte layer through a sintering process to locally provide electronic conductivity to the inside of the electrolyte layer, thereby eliminating the need for forming a multilayer electrolyte structure requiring a complicated manufacturing process as in the prior art. It is possible to manufacture a solid oxide fuel cell which can ensure durability against voltage and also prevent leakage current.
  • I-V current-voltage
  • FIG. 2 is a flowchart illustrating each step of a method of manufacturing a solid oxide fuel cell in which reverse voltage degradation is prevented according to the present invention.
  • FIG. 3 is a flow chart illustrating each step of the SOFC cell manufacturing process having a gradient anode / electrolyte structure according to an embodiment of the present invention.
  • FIG. 4 is a schematic cross-sectional view of an SOFC cell having a gradient anode / electrolyte structure manufactured according to an embodiment of the present disclosure.
  • FIG. 6 (a) is a graph showing a voltage change with time when a constant current (CC) is applied to a conventional SOFC cell including a YSZ electrolyte layer
  • FIG. 6 (b) is a graph showing a measurement result of a corresponding constant current test IV
  • 6 (c) is a scanning electron microscope (SEM) photograph showing the cell cross-sectional microstructure after the constant current test.
  • FIG. 7 (a) is a graph showing the voltage change over time when applying a constant current (CC) for the SOFC cell manufactured in the present embodiment
  • Figure 7 (b) is a graph showing the result of the constant current test IV measurement
  • FIG. 7 (c) is a scanning electron microscope (SEM) photograph showing the cell cross-sectional microstructure after the constant current test.
  • Embodiments according to the concepts of the present invention may be variously modified and may have various forms, and specific embodiments will be illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiments in accordance with the concept of the present invention to a particular disclosed form, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.
  • steps (1) to (6) below were sequentially performed to fabricate an SOFC unit cell having a gradient anode / electrolyte structure having a cross-sectional schematic diagram shown in FIG. 4.
  • NiO, YSZ, and ceria were mixed at a ratio of 60 wt%: 20 wt%: 20 wt%, respectively, for the production of the anode functional layer (AFL), and further grinding was performed using a planetary ball mill to refine the particles.
  • the anode functional layer mixed with LSM and YSZ was screen printed on the sintered cell and heat-treated at 1170 °C for 1 hour.
  • Anode made of LSM was screen printed on the anode functional layer and heat-treated at 1160 ° C for 1 hour.
  • EDS analysis was performed to analyze how the ceria diffused into the electrolyte during sintering of the unit cell prepared in the above example.
  • FIG. 5 which shows the results of EDS analysis, it was found that cerium diffused about 3 microns in a 15 micron thick electrolyte. Through this, it can be seen that a region having a local electron conductivity exists inside the YSZ electrolyte.
  • the cell to which the gradient anode / electrolyte manufactured in the present embodiment is applied maintains the voltage under high voltage and low voltage as well as in reverse voltage (FIG. 7 (a)).
  • the performance is also not significantly different from the existing YSZ cell (Fig. 7 (b)), and the post analysis showed that no physical damage occurs between the anode and the electrolyte interface (Fig. 7 (c)).
  • the cerium ions are diffused into the electrolyte layer from the layer containing ceria provided on the cathode side through a high temperature sintering process.
  • a solid oxide fuel cell having a gradient anode / electrolyte structure in which cerium concentration decreases from the electrolyte layer interface toward the center of the electrolyte layer may be manufactured, and the solid oxide fuel cell may have an electrolyte close to the cathode / electrolyte interface.
  • the cerium ions are diffused into the single layer of the electrolyte layer through the sintering process to locally supply the electronic conductivity to the inside of the electrolyte layer, thereby eliminating the need to form a multilayer electrolyte structure requiring a complicated manufacturing process as in the prior art. It is possible to manufacture a solid oxide fuel cell that can ensure durability against reverse voltage and also prevent leakage current.
  • cerium ions are diffused into an electrolyte layer composed of a single layer through a sintering process, thereby providing a locally electronic conductivity inside the electrolyte layer, as in the prior art. It is possible to manufacture a solid oxide fuel cell capable of securing durability against reverse voltage and preventing leakage current without forming a multilayer electrolyte structure requiring a complicated manufacturing process.

Abstract

The present invention pertains to a method for manufacturing a solid oxide fuel cell in which degradation due to a negative cell voltage is prevented, the method comprising: a step for preparing a solid oxide fuel cell unit cell in which an anode layer having a ceria (CeO2)-containing layer formed on one surface thereof, an electrolyte layer formed on the ceria-containing layer and containing yttria-stabilized zirconia (YSZ), and a cathode layer are sequentially stacked; and (b) a step for sintering the solid oxide fuel cell unit cell. According to the method for manufacturing a solid oxide fuel cell (SOFC) of the present invention, a solid oxide fuel cell having a gradient anode/electrolyte structure in which the concentration of cerium gradually decreases from the anode/electrolyte layer interface to the center of the electrolyte layer can be produced through the sintering step in which cerium ions diffuse into the electrolyte layer from the ceria-containing layer provided in the anode. The solid oxide fuel cell has N-type conductivity locally only in an electrolyte section near the anode/electrolyte interface, and can thus effectively prevent anode/electrolyte separation in negative cell voltage situations. Furthermore, since only a portion of the inside of the electrolyte has N-type conductivity, leakage currents can also be prevented.

Description

역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법Manufacturing Method of Solid Oxide Fuel Cell Preventing Reverse Voltage Degradation
본 발명은 (i) 산업통상자원부 시행 국가연구개발사업(과제고유번호:20163030031850, 사업명:에너지기술개발사업, 연구과제명:분산 발전용 고 신뢰성 SOFC 스택 제조 기술 개발, 연구관리전문기관:에너지기술평가원, 주관기관:(주)미코, 연구기간:2017.10.01 ~ 2018.07.30) 및 (ii) 과학기술정보통신부 시행 국가연구개발사업(과제고유번호:2017M1A2A2045018, 사업명:기후변화대응기술개발사업, 연구과제명: SOFC 스택 디자인 최적화를 위한 in-situ 진단 기술 개발, 연구관리전문기관:한국연구재단, 주관기관:창원대학교 산학협력단, 연구기간:2018.05.01 ~ 2019.02.28)의 연구개발 지원 하에 창원대학교가 수행한 결과물로서, The present invention is (i) Ministry of Trade, Industry and Energy's national research and development project (project unique number: 20163030031850, business name: energy technology development project, research project name: development of high reliability SOFC stack manufacturing technology for distributed generation, research management professional organization: energy technology Assessment Agency, Organizer: Mico Corporation, Research Period: 2017.10.01 ~ 2018.07.30) and (ii) National R & D project implemented by Ministry of Science and Technology Information and Communication (Project number: 2017M1A2A2045018, Project name: Climate change technology development project, Project Title: Development of in-situ diagnostic technology for optimizing SOFC stack design, Research and management agency: Korea Research Foundation, Organized by Changwon National University Industry-University Cooperation Group, Research Period: 2018.05.01 ~ 2019.02.28) As a result of Changwon University,
고체산화물 연료전지의 제조방법에 대한 것이며, 보다 상세하게는, 역 전압(negative cell voltage) 하에서 SOFC 셀 스택의 열화 현상을 방지할 수 있는 구조를 가지는 전해질층을 포함한 고체산화물 연료전지의 제조방법에 대한 것이다.The present invention relates to a method for manufacturing a solid oxide fuel cell, and more particularly, to a method for manufacturing a solid oxide fuel cell including an electrolyte layer having a structure capable of preventing degradation of an SOFC cell stack under a negative cell voltage. It is about.
미래 에너지와 공해문제로 인해 친환경 에너지 자원에 대한 관심이 높아지고 있다. 친환경 에너지 기술의 하나로서 수소와 산소의 화학반응에 의해 화학에너지를 전기에너지로 변환하여 비연소과정인 전기화학반응을 통해 이산화탄소 등의 공해를 배출 하지 않는 고체 산화물 연료전지가 신재생 에너지로서 주목 받고 있다. Due to future energy and pollution problems, interest in environmentally friendly energy resources is increasing. As one of the eco-friendly energy technologies, solid oxide fuel cells that convert chemical energy into electrical energy by chemical reaction between hydrogen and oxygen and do not emit pollution such as carbon dioxide through electrochemical reaction, which is a non-combustion process, are attracting attention as renewable energy. have.
하지만, 연료전지의 기전력은 단위 셀 하나 당 최대 1V 정도로 원하는 출력을 얻기 위해서는 직렬로 여러 장의 셀을 스태킹(stacking)하는 단계가 필요하다. 이때, 스택 내에서 하나의 셀이 큰 성능 편차를 보인다면 낮은 성능을 보이는 셀이 임계 전류 값 이상에서 역 전압(negative cell voltage)으로 작동하여 급격한 열화로 물리적 파괴가 일어나 스택 전체의 작동이 멈추게 된다(도 1). 이와 같은 현상은 실제로 직렬로 연결된 전기화학 장치에서 보편적으로 발생하는 현상으로 전지의 안정성과 상용화를 위해서는 셀 간 성능편차를 최소화해야한다. However, the electromotive force of a fuel cell is about 1V maximum per unit cell, and stacking several cells in series is necessary to obtain a desired output. At this time, if one cell in the stack exhibits a large performance deviation, the low performing cell operates at a negative cell voltage above the threshold current value, causing physical destruction due to rapid deterioration, thereby stopping the entire stack operation. (FIG. 1). This phenomenon is a phenomenon commonly occurring in electrochemical devices connected in series. In order to stabilize and commercialize a battery, performance deviation between cells must be minimized.
현재 고체산화물 연료전지의 전해질로 가장 널리 사용되는 물질은 8mol% 이트리아(yttria)가 도핑된 지르코니아(YSZ) 이다. YSZ는 이트리아의 첨가로 인해 발생된 산소빈자리에 의해 산소 이온 전도성이 지배적인 물질로 전자 전도성을 거의 보이지 않으며 산화/환원 분위기에 관계없이 화학적으로 안정하다는 장점을 가진다. Currently, the most widely used material for electrolytes of solid oxide fuel cells is zirconia (YSZ) doped with 8 mol% yttria. YSZ has a merit that oxygen ion conductivity is dominant due to oxygen vacancies generated by the addition of yttria, which shows little electronic conductivity and is chemically stable regardless of the oxidation / reduction atmosphere.
여기서 산소이온 전도성이라는 점은 관점의 차이에 따라 다른 양상을 보이게 된다. 성능 관점에서 순수한 산소 이온 전도성은 높은 개방회로 전압과 이에 따른 높은 출력이 장점으로 작용된다. 그러나, 내구성 관점에서 순수한 산소 이온 전도성은 더 이상 장점으로 작용하지 않는다. Here, the oxygen ion conductivity is different depending on the point of view. In terms of performance, pure oxygen ion conductivity has the advantage of high open circuit voltage and therefore high power. However, in terms of durability, pure oxygen ion conductivity no longer serves as an advantage.
위에 언급한 역 전압에서의 작동은 고체 전해질 내부에 비정상적으로 높은 산소화학 포텐셜을 형성하여 전극과 전해질 계면의 박리를 일으킬 수 있다. 즉, 연료전지 스택 운전을 계속 진행하기 위해서는 역 전압에서도 열화 없이 작동 할 수 있는 기술이 필요하다. Operation at the reverse voltage mentioned above can cause abnormally high oxygen chemistry potentials inside the solid electrolyte, resulting in delamination of the electrode and electrolyte interface. In other words, in order to continue the fuel cell stack operation, a technology that can operate without deterioration even at a reverse voltage is required.
이와 관련해, 한국 등록특허 제10-1180182호(내박리성이 우수한 고체산화물 연료전지)에서는 삼중층 전해질을 이용하여 연료극에 가까운 전해질 층에만 세리아(ceria) 성분을 포함시켜 전자 전도성을 부여함으로써 누설 전류를 방지하고 역 전압에 대한 열화를 억제하였다. 하지만, 이러한 다층 전해질 구조는 제조 공정을 복잡하게 하고, 두꺼운 전해질로 인해 저항이 상승할 수 있으며, 층과 층 사이의 계면 저항이 발생할 수 있는 등 여러 단점을 내포하고 있다.In this regard, Korean Patent No. 10-1180182 (a solid oxide fuel cell with excellent peeling resistance) uses a triple layer electrolyte to include a ceria component only in an electrolyte layer close to an anode to impart electronic conductivity, thereby providing leakage current. And deterioration to the reverse voltage was suppressed. However, such a multilayer electrolyte structure has several drawbacks, such as complicated manufacturing process, high resistance due to thick electrolyte, and interfacial resistance between layers.
본 발명이 해결하고자 하는 기술적 과제는, 종래기술이 가지는 전해질층 제조 공정의 복잡성 및 저항 증가 등의 문제를 발생시키지 않으면서도 역 전압 상황에서 음극층 및 전해질층 간의 박리를 효과적으로 방지할 수 있는 고체산화물 연료전지 제조방법을 제공하는 것이다.The technical problem to be solved by the present invention is a solid oxide that can effectively prevent the separation between the negative electrode layer and the electrolyte layer in a reverse voltage situation without generating problems such as the complexity and resistance of the electrolyte layer manufacturing process of the prior art It is to provide a fuel cell manufacturing method.
기존 YSZ(Yttria-stabilized zirconia)를 포함하는 전해질을 사용한 셀의 역 전압에 의한 열화를 연구한 논문에 의하면, YSZ 전해질을 사용한 셀은 시간 당 전압의 감소뿐 아니라 작동 후, 개방회로전압 및 출력밀도의 감소를 보였으며, 사후분석 결과, 음극과 전해질 계면에 박리가 관찰되는 것을 알 수 있다.According to a paper that studies the deterioration caused by the reverse voltage of a cell using an electrolyte containing Yttria-stabilized zirconia (YSZ), the cell using the YSZ electrolyte not only reduces the voltage per hour, but also the open circuit voltage and power density after operation. After the analysis, it was found that exfoliation was observed at the interface between the anode and the electrolyte.
이러한 음극과 전해질 계면간의 박리현상의 원인은 역 전압에 의한 음극/전해질 계면에서의 높은 산소분압에 의한 것으로서 박리현상을 방지하기 위해서는 계면의 산소분압을 감소시키는 것이 관건이다.The cause of the peeling phenomenon between the negative electrode and the electrolyte interface is due to the high oxygen partial pressure at the negative electrode / electrolyte interface due to the reverse voltage. It is important to reduce the oxygen partial pressure at the interface to prevent the peeling phenomenon.
전자 전도성을 보이는 세리아(ceria)와 같은 도펀트(dopant)가 첨가된 YSZ를 전해질로 사용할 경우 도펀트에 의한 전자 전도성으로 역 전압 작동 시 발생하는 음극/전해질 계면의 높은 산소분압이 감소해 박리를 일으키지 않는다. 하지만, 단층 YSZ 전해질 모든 영역에 세리아를 첨가할 경우, 누설 전류가 발생할 수 있다.When YSZ containing dopant such as ceria, which exhibits electronic conductivity, is used as an electrolyte, the electronic conductivity of the dopant reduces the high oxygen partial pressure at the cathode / electrolyte interface generated during reverse voltage operation, which does not cause peeling. . However, when ceria is added to all regions of the single layer YSZ electrolyte, leakage current may occur.
반면, 앞서 배경기술에서 설명하였듯이 다층 구조 전해질을 구성하면 누설 전류는 방지할 수 있지만, 제조공정의 복잡화와 전해질 두께 상승, 계면 저항과 같은 문제가 발생할 수 있다.On the other hand, as described in the background art, when the multilayered electrolyte is formed, leakage current can be prevented, but problems such as complicated manufacturing process, electrolyte thickness increase, and interface resistance can occur.
따라서, 본 발명은 전해질 내부에 직접적으로 세리아(ceria)를 첨가하지 않는 방법으로서, 셀 제조 과정 중 전자전도성을 지닌 세리아(ceria)를 함유하는 음극층을 일면에 형성시키고, 상기 셀을 소결해 고온 확산을 통해 세륨(cerium) 이온이 YSZ(Yttria-stabilized zirconia)를 포함하는 전해질층 내부에 용해되어 국부적으로 전자 전도성을 띄게 하는 경사형 음극/전해질(Gradient anode/electrolyte)를 적용한 셀의 제조방법을 제공한다.Accordingly, the present invention is a method of not directly adding ceria to the inside of an electrolyte, and forms a negative electrode layer containing ceria having electronic conductivity on one surface during cell manufacturing, and sinters the cell to obtain a high temperature. A method of fabricating a cell using a gradient anode / electrolyte in which cerium ions are dissolved inside an electrolyte layer containing YSZ (Yttria-stabilized zirconia) through diffusion to make local electron conductivity. to provide.
구체적으로, 전술한 기술적 과제를 달성하기 위해, 본 발명은 (a) 세리아(CeO2)를 포함하는 층이 일면에 형성된 음극(anode)층; 상기 세리아를 포함하는 층 위에 형성되며, YSZ(Yttria-stabilized zirconia)를 포함하는 전해질(electrolyte)층; 및 양극(cathode)층의 순서대로 적층된 고체산화물 연료전지 단위 셀을 제조하는 단계; 및 (b) 상기 고체산화물 연료전지 단위 셀을 소결하는 단계;를 포함하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법을 제공한다.Specifically, in order to achieve the above technical problem, the present invention (a) an anode layer having a layer containing ceria (CeO 2 ) formed on one surface; An electrolyte layer formed on the layer including ceria and including Yttria-stabilized zirconia (YSZ); And manufacturing a solid oxide fuel cell unit cell stacked in the order of the cathode layer. And (b) sintering the solid oxide fuel cell unit cell, wherein the reverse voltage degradation phenomenon is prevented.
상기 단계 (a)에서 단위 셀 적층체를 제조함에 있어서, 상기 음극층은, 음극 지지층(Anode Support, AS) 및 상기 세리아를 포함하는 층으로서 음극 지지층 상에 형성되는 음극 기능층(Anode Functional Layer, AFL)을 포함해 이루어질 수 있다.In manufacturing the unit cell stack in the step (a), the negative electrode layer is an anode functional layer (Anode Functional Layer,) formed on the negative electrode support layer as a layer comprising an anode support (AS) and the ceria AFL).
이때, 상기 음극 지지층 및 음극 기능층은 니켈(Ni)계 소재로 이루어질 수 있으며, 나아가, 상기 음극 지지층은 니켈 및 YSZ를 포함하고, 상기 음극 기능층은 니켈, YSZ 및 세리아를 포함할 수 있다.In this case, the negative electrode support layer and the negative electrode functional layer may be made of a nickel (Ni) -based material, and further, the negative electrode support layer may include nickel and YSZ, and the negative electrode functional layer may include nickel, YSZ and ceria.
또한, 상기 양극층은, 상기 전해질층 상에 형성된 양극 기능층(Cathode Functional Layer, CFL) 및 상기 양극 기능층 상에 형성된 양극 집전층(Current Collector, CC)을 포함할 수 있으며, 일례로, 상기 양극 기능층은 LSM(Sr-doped LaMnO3) 및 YSZ를 포함하고, 상기 양극 집전층은 LSM을 포함할 수 있다.In addition, the anode layer may include a cathode functional layer (CFL) formed on the electrolyte layer and a cathode collector layer (Current Collector, CC) formed on the anode functional layer. For example, The positive electrode functional layer may include SSM (Sr-doped LaMnO 3 ) and YSZ, and the positive electrode current collector layer may include an LSM.
상기 단계 (b)에서는 상기 단계 (a)에서 제조된 단위 셀을 소결하는 단계로서, 소결을 통해 세륨(cerium) 이온을 음극측에 구비된 세리아를 포함하는 층으로부터 전해질층 내부로 확산시켜 음극/전해질층 계면으로부터 전해질층 중심부 측으로 갈수록 세륨 농도가 감소하는 경사 구조(gradient structure)를 형성하게 된다.In step (b), the unit cell prepared in step (a) is sintered, and the cerium ions are diffused into the electrolyte layer from the layer containing ceria provided on the cathode side through sintering. A gradient structure in which the cerium concentration decreases toward the center of the electrolyte layer from the electrolyte layer interface is formed.
이때, 상기 단계 (b)에서의 소결조건은 음극층 및 전해질층 계면으로부터 전해질층 방향으로 소정의 두께(단, 전해질층 전체 두께보다는 작아야 함)만큼의 경사 구조를 형성시킬 수 있다면 소결온도 및 시간은 특별히 제한되지는 않으며, 일례로, 1410 내지 1510 ℃의 온도에서 1 내지 11 시간 동안 실시할 수 있다.At this time, the sintering conditions in the step (b) is a sintering temperature and time if the inclined structure of a predetermined thickness (but should be smaller than the total thickness of the electrolyte layer) from the cathode layer and the electrolyte layer interface can be formed Is not particularly limited, and may be, for example, 1 to 11 hours at a temperature of 1410 to 1510 ℃.
그리고, 본 발명은 발명의 다른 측면에서, 상기 제조방법에 의해 제조된 고체산화물 연료전지 단위 셀을 제공한다.In another aspect of the present invention, there is provided a solid oxide fuel cell unit cell manufactured by the manufacturing method.
나아가, 본 발명은 발명의 또 다른 측면에서, 상기 단위 셀을 복수 개 포함하는 고체산화물 연료전지 스택을 제공한다.Furthermore, in another aspect of the present invention, a solid oxide fuel cell stack including a plurality of unit cells is provided.
본 발명에 따른 고체산화물 연료전지(SOFC)의 제조방법에 의하면, 소결 공정을 통해 세륨(cerium) 이온을 음극측에 구비된 세리아를 포함하는 층으로부터 전해질층 내부로 확산시켜 음극/전해질층 계면으로부터 전해질층 중심부 측으로 갈수록 세륨 농도가 감소하는 경사형 음극/전해질(Gradient anode/electrolyte) 구조의 고체산화물 연료전지를 제조할 수 있으며, 상기 고체산화물 연료전지는 음극/전해질 계면에 가까운 전해질 구간만 국부적으로 전자 전도성(N-type)을 가지고 있어 역 전압 상황에서 음극/전해질 박리를 효과적으로 방지할 수 있고, 전해질 내부 중 일부만이 전자 전도성을 지니므로 누설 전류 또한 방지할 수 있다.According to the method for manufacturing a solid oxide fuel cell (SOFC) according to the present invention, through the sintering process, cerium ions are diffused from the layer containing ceria provided on the cathode side into the electrolyte layer from the cathode / electrolyte layer interface. A solid oxide fuel cell having a gradient anode / electrolyte structure in which cerium concentration decreases toward the center of the electrolyte layer may be manufactured, and the solid oxide fuel cell may locally have only an electrolyte section close to the cathode / electrolyte interface. It has an electron conductivity (N-type) to effectively prevent the negative electrode / electrolyte peeling in the reverse voltage situation, and since only a part of the inside of the electrolyte has an electronic conductivity it can also prevent the leakage current.
즉, 소결 공정을 통해 세륨(cerium) 이온을 단층으로 이루어진 전해질층 내부로 확산시켜 전해질층 내부에 국부적으로 전자 전도성 부여함으로써 종래기술과 같이 복잡한 제조공정을 요하는 다층 전해질 구조를 형성할 필요 없이 역 전압에 대한 내구성이 확보되고 누설전류 또한 방지할 수 있는 고체산화물 연료전지를 제조할 수 있다.In other words, the cerium ions are diffused into a single layer of an electrolyte layer through a sintering process to locally provide electronic conductivity to the inside of the electrolyte layer, thereby eliminating the need for forming a multilayer electrolyte structure requiring a complicated manufacturing process as in the prior art. It is possible to manufacture a solid oxide fuel cell which can ensure durability against voltage and also prevent leakage current.
도 1은 정상 셀 스택과 불량 셀이 포함된 셀 스택 각각에 대한 I-V(전류-전압) 그래프이다.1 is an I-V (current-voltage) graph for each cell stack including a normal cell stack and a bad cell.
도 2는 본 발명에 따른 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법의 각 단계를 나타낸 흐름도이다.2 is a flowchart illustrating each step of a method of manufacturing a solid oxide fuel cell in which reverse voltage degradation is prevented according to the present invention.
도 3은 본원 실시예에 따른 경사형 음극/전해질(Gradient anode/electrolyte) 구조를 가지는 SOFC 셀 제조 과정의 각 단계를 나타낸 흐름도이다.3 is a flow chart illustrating each step of the SOFC cell manufacturing process having a gradient anode / electrolyte structure according to an embodiment of the present invention.
도 4는 본원 실시예에 따라 제조되는 경사형 음극/전해질(Gradient anode/electrolyte) 구조를 가지는 SOFC 셀의 단면 모식도이다.4 is a schematic cross-sectional view of an SOFC cell having a gradient anode / electrolyte structure manufactured according to an embodiment of the present disclosure.
도 5은 본원 실시예에 따라 제조된 SOFC 셀에 대한 EDS line 분석 결과이다.5 is an EDS line analysis result for the SOFC cell prepared according to the present embodiment.
도 6(a)는 종래의 YSZ 전해질층 포함 SOFC 셀에 대해 정전류(CC) 인가시 시간에 따른 전압 변화를 보여주는 그래프이며, 도 6(b)는 해당 정전류 테스트 I-V 측정 결과를 보여주는 그래프이며, 도 6(c)는 해당 정전류 테스트 후의 셀 단면 미세구조를 보여주는 주사전자현미경(SEM) 사진이다.FIG. 6 (a) is a graph showing a voltage change with time when a constant current (CC) is applied to a conventional SOFC cell including a YSZ electrolyte layer, and FIG. 6 (b) is a graph showing a measurement result of a corresponding constant current test IV. 6 (c) is a scanning electron microscope (SEM) photograph showing the cell cross-sectional microstructure after the constant current test.
도 7(a)는 본원 실시예에서 제조된 SOFC 셀에 대해 정전류(CC) 인가시 시간에 따른 전압 변화를 보여주는 그래프이며, 도 7(b)는 해당 정전류 테스트 I-V 측정 결과를 보여주는 그래프이며, 도 7(c)는 해당 정전류 테스트 후의 셀 단면 미세구조를 보여주는 주사전자현미경(SEM) 사진이다.7 (a) is a graph showing the voltage change over time when applying a constant current (CC) for the SOFC cell manufactured in the present embodiment, Figure 7 (b) is a graph showing the result of the constant current test IV measurement, FIG. 7 (c) is a scanning electron microscope (SEM) photograph showing the cell cross-sectional microstructure after the constant current test.
본 발명을 설명함에 있어서 관련된 공지 기능 또는 구성에 대한 구체적인 설명이 본 발명의 요지를 불필요하게 흐릴 수 있다고 판단되는 경우에는 그 상세한 설명을 생략할 것이다.In the following description of the present invention, if it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.
본 발명의 개념에 따른 실시예는 다양한 변경을 가할 수 있고 여러 가지 형태를 가질 수 있으므로 특정 실시예를 도면에 예시하고 본 명세서 또는 출원에 상세하게 설명하고자 한다. 그러나 이는 본 발명의 개념에 따른 실시 예를 특정한 개시 형태에 대해 한정하려는 것이 아니며, 본 발명의 사상 및 기술 범위에 포함되는 모든 변경, 균등물 내지 대체물을 포함하는 것으로 이해되어야 한다.Embodiments according to the concepts of the present invention may be variously modified and may have various forms, and specific embodiments will be illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiments in accordance with the concept of the present invention to a particular disclosed form, it should be understood to include all changes, equivalents, and substitutes included in the spirit and scope of the present invention.
본 명세서에서 사용한 용어는 단지 특정한 실시예를 설명하기 위해 사용된 것으로, 본 발명을 한정하려는 의도가 아니다. 단수의 표현은 문맥상 명백하게 다르게 뜻하지 않는 한, 복수의 표현을 포함한다. 본 명세서에서, "포함하다" 또는 "가지다" 등의 용어는 설시된 특징, 숫자, 단계, 동작, 구성요소, 부분품 또는 이들을 조합한 것이 존재함을 지정하려는 것이지, 하나 또는 그 이상의 다른 특징들이나 숫자, 단계, 동작, 구성요소, 부분품 또는 이들을 조합한 것들의 존재 또는 부가 가능성을 미리 배제하지 않는 것으로 이해되어야 한다.The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. As used herein, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, action, component, part, or combination thereof that is described, and that one or more other features or numbers are present. It should be understood that it does not exclude in advance the possibility of the presence or addition of steps, actions, components, parts or combinations thereof.
이하, 실시예를 통해 본 발명을 보다 상세히 설명하도록 한다.Hereinafter, the present invention will be described in more detail with reference to Examples.
<실시예><Example>
도 3에 도시한 바와 같이 아래 (1) 내지 (6)의 단계를 순차적으로 실시해 도 4에 도시된 단면 모식도를 가지는 경사형 음극/전해질(Gradient anode/electrolyte) 구조의 SOFC 단위 셀을 제조하였다.As shown in FIG. 3, steps (1) to (6) below were sequentially performed to fabricate an SOFC unit cell having a gradient anode / electrolyte structure having a cross-sectional schematic diagram shown in FIG. 4.
(1) NiO와 YSZ로 이루어진 anode powder를 die-press 한 후 950℃에서 1시간 열처리하여 음극지지층(AS)을 제조하였다.(1) After the die-press of anode powder composed of NiO and YSZ, heat treatment was performed at 950 ° C. for 1 hour to prepare a cathode support layer (AS).
(2) 음극 기능층 (AFL) 제조를 위해서 NiO, YSZ, ceria를 각각 60 wt% : 20 wt% : 20 wt% 비율로 혼합하였으며 입자 미세화를 위해 유성볼밀을 이용하여 추가 분쇄 공정을 실시하였다.(2) NiO, YSZ, and ceria were mixed at a ratio of 60 wt%: 20 wt%: 20 wt%, respectively, for the production of the anode functional layer (AFL), and further grinding was performed using a planetary ball mill to refine the particles.
(3) 분쇄 후 부탄올 용매를 이용하여 슬러리로 제조하였으며 앞서 제조한 AS 층에 drop 코팅하여 950℃에서 1시간 열처리 하였다.(3) After grinding, a slurry was prepared using a butanol solvent, and drop-coated to the AS layer prepared above, and then heat-treated at 950 ° C. for 1 hour.
(4) 열처리된 AS/AFL substrate 에 YSZ 슬러리를 drop 코팅하여 1460℃에서 6시간 동안 소결하였다.(4) YSZ slurry was drop coated on the heat treated AS / AFL substrate and sintered at 1460 ° C. for 6 hours.
(5) LSM과 YSZ를 혼합한 양극기능층을 소결한 셀 위에 screen print 하고 1170℃에서 1시간 열처리 하였다.(5) The anode functional layer mixed with LSM and YSZ was screen printed on the sintered cell and heat-treated at 1170 ℃ for 1 hour.
(6) 양극 기능층 위에 LSM으로 이루어진 양극을 screen print 하고 1160℃에서 1시간 열처리 하였다.(6) Anode made of LSM was screen printed on the anode functional layer and heat-treated at 1160 ° C for 1 hour.
<실험예>Experimental Example
1. 소결 후 Ceria 확산 거리 분석 1. Analysis of Ceria Diffusion Distance after Sintering
상기 실시예에서 제조된 단위 셀에 대해 소결 중 세리아가 전해질 내부에 얼마나 확산 하였는지 분석하기 위해 EDS 분석을 실시하였다.EDS analysis was performed to analyze how the ceria diffused into the electrolyte during sintering of the unit cell prepared in the above example.
EDS 분석결과를 도시한 도 5에서 볼 수 있듯이, 15 마이크론 두께의 전해질에 세륨이 약 3 마이크론 정도 확산했음을 알 수 있었다. 이를 통해 YSZ 전해질 내부에 국부적으로 전자전도성을 가지는 영역이 존재함을 알 수 있다. As shown in FIG. 5, which shows the results of EDS analysis, it was found that cerium diffused about 3 microns in a 15 micron thick electrolyte. Through this, it can be seen that a region having a local electron conductivity exists inside the YSZ electrolyte.
2. 역 전압 내구성 테스트2. Reverse voltage durability test
역 전압 작동 하에서의 내구성을 확인하기 위해 고전압 (0.6V ~ 0.7V), 저전압 (0.2V ~ 0.4V), 역 전압 (-0.3V ~ -0.4V) 순으로 정전류 테스트를 진행하여 역 전압 상황에서의 전압 강하 현상이 나타나는지 알아보고, 정전류 테스트 전/후 출력밀도 측정을 실시하였다. 이를 통해 기존 YSZ 전해질 셀과의 전압강하, 성능비교를 진행하였다. To check the durability under reverse voltage operation, constant current tests are conducted in the order of high voltage (0.6V to 0.7V), low voltage (0.2V to 0.4V), reverse voltage (-0.3V to -0.4V), The voltage drop phenomenon was observed and the output density measurement was performed before and after the constant current test. Through this, voltage drop and performance comparison with the existing YSZ electrolyte cell were performed.
YSZ 전해질 셀의 역 전압 테스트 결과 논문에 보고 된 바와 같이 고전압과 저전압에서 보이지 않던 전압 강하 현상이 나타났으며(도 6(a)), 역 전압 테스트 후 출력 감소 현상 또한 관찰된다(도 6(b)). 테스트 후 SEM 분석을 통한 이미지(도 6(c))에서도 볼 수 있듯이 음극과 전해질 계면간의 박리가 관찰되었다. As a result of the reverse voltage test of the YSZ electrolyte cell, as shown in the paper, there was a voltage drop which was not seen at the high voltage and the low voltage (Fig. 6 (a)). )). As can be seen in the image (Fig. 6 (c)) through the SEM analysis after the test, the separation between the cathode and the electrolyte interface was observed.
반면에, 본원 실시예에서 제조된 경사형 음극/전해질(Gradient anode/electrolyte)를 적용한 셀은 고전압, 저전압 뿐 아니라 역 전압 상황에서도 전압이 유지됨을 알 수 있다(도 7(a)). 성능 또한 기존 YSZ셀과 크게 다르지 않으며(도 7(b)), 사후 분석결과 음극과 전해질 계면간의 어떠한 물리적 손상도 일어나지 않음을 알 수 있었다(도 7(c)).On the other hand, it can be seen that the cell to which the gradient anode / electrolyte manufactured in the present embodiment is applied maintains the voltage under high voltage and low voltage as well as in reverse voltage (FIG. 7 (a)). The performance is also not significantly different from the existing YSZ cell (Fig. 7 (b)), and the post analysis showed that no physical damage occurs between the anode and the electrolyte interface (Fig. 7 (c)).
앞서 상세히 설명한 본 발명에 따른 고체산화물 연료전지(SOFC)의 제조방법에 의하면, 고온 소결 공정을 통해 세륨(cerium) 이온을 음극측에 구비된 세리아를 포함하는 층으로부터 전해질층 내부로 확산시켜 음극/전해질층 계면으로부터 전해질층 중심부 측으로 갈수록 세륨 농도가 감소하는 경사형 음극/전해질(Gradient anode/electrolyte) 구조의 고체산화물 연료전지를 제조할 수 있으며, 상기 고체산화물 연료전지는 음극/전해질 계면에 가까운 전해질 구간만 국부적으로 전자 전도성(N-type)을 가지고 있어 역 전압 상황에서 음극/전해질 박리를 효과적으로 방지할 수 있고, 전해질 내부 중 일부만이 전자 전도성을 지니므로 누설 전류 또한 방지할 수 있다.According to the method of manufacturing a solid oxide fuel cell (SOFC) according to the present invention described above in detail, the cerium ions are diffused into the electrolyte layer from the layer containing ceria provided on the cathode side through a high temperature sintering process. A solid oxide fuel cell having a gradient anode / electrolyte structure in which cerium concentration decreases from the electrolyte layer interface toward the center of the electrolyte layer may be manufactured, and the solid oxide fuel cell may have an electrolyte close to the cathode / electrolyte interface. Only the section has a local electron conductivity (N-type) can effectively prevent the negative electrode / electrolyte peeling in the reverse voltage situation, and since only a part of the inside of the electrolyte has an electronic conductivity it can also prevent the leakage current.
즉, 소결 공정을 통해 세륨(cerium) 이온을 단층으로 이루어진 전해질층 내부로 확산시켜 전해질층 내부에 국부적으로 전자 전도성을 부여함으로써 종래기술과 같이 복잡한 제조공정을 요하는 다층 전해질 구조를 형성할 필요 없이 역 전압에 대한 내구성이 확보되고 누설전류 또한 방지할 수 있는 고체산화물 연료전지를 제조할 수 있다.In other words, the cerium ions are diffused into the single layer of the electrolyte layer through the sintering process to locally supply the electronic conductivity to the inside of the electrolyte layer, thereby eliminating the need to form a multilayer electrolyte structure requiring a complicated manufacturing process as in the prior art. It is possible to manufacture a solid oxide fuel cell that can ensure durability against reverse voltage and also prevent leakage current.
이상, 첨부된 도면을 참조하여 본 발명의 실시예를 설명하였지만, 본 발명이 속하는 기술분야에서 통상의 지식을 가진 자는 본 발명이 그 기술적 사상이나 필수적인 특징을 변경하지 않고서 다른 구체적인 형태로 실시될 수 있다는 것을 이해할 수 있을 것이다. 그러므로 이상에서 기술한 실시예 에는 모든 면에서 예시적인 것이며 한정적이 아닌 것으로 이해해야만 한다.Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. You will understand that there is. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.
본 발명에 따른 고체산화물 연료전지(SOFC)의 제조방법에 의하면, 소결 공정을 통해 세륨(cerium) 이온을 단층으로 이루어진 전해질층 내부로 확산시켜 전해질층 내부에 국부적으로 전자 전도성 부여함으로써 종래기술과 같이 복잡한 제조공정을 요하는 다층 전해질 구조를 형성할 필요 없이 역 전압에 대한 내구성이 확보되고 누설전류 또한 방지할 수 있는 고체산화물 연료전지를 제조할 수 있다.According to the method of manufacturing a solid oxide fuel cell (SOFC) according to the present invention, cerium ions are diffused into an electrolyte layer composed of a single layer through a sintering process, thereby providing a locally electronic conductivity inside the electrolyte layer, as in the prior art. It is possible to manufacture a solid oxide fuel cell capable of securing durability against reverse voltage and preventing leakage current without forming a multilayer electrolyte structure requiring a complicated manufacturing process.

Claims (10)

  1. (a) 세리아(CeO2)를 포함하는 층이 일면에 형성된 음극(anode)층; 상기 세리아를 포함하는 층 위에 형성되며, YSZ(Yttria-stabilized zirconia)를 포함하는 전해질(electrolyte)층; 및 양극(cathode)층의 순서대로 적층된 고체산화물 연료전지 단위 셀을 제조하는 단계; 및(a) an anode layer having a layer containing ceria (CeO 2 ) formed on one surface thereof; An electrolyte layer formed on the layer including ceria and including Yttria-stabilized zirconia (YSZ); And manufacturing a solid oxide fuel cell unit cell stacked in the order of the cathode layer. And
    (b) 상기 고체산화물 연료전지 단위 셀을 소결하는 단계;를 포함하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법.(b) sintering the solid oxide fuel cell unit cell, wherein the reverse voltage degradation is prevented.
  2. 제1항에 있어서,The method of claim 1,
    상기 음극층은,The cathode layer,
    음극 지지층(Anode Support, AS); 및 An anode support (AS); And
    상기 음극 지지층 상에 형성되며 세리아를 포함하는 음극 기능층(Anode Functional Layer, AFL)을 포함하는 것을 특징으로 하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법.And a negative electrode functional layer (AFL) formed on the negative electrode support layer and including ceria.
  3. 제2항에 있어서,The method of claim 2,
    상기 음극 지지층 및 음극 기능층은 니켈(Ni)계 소재로 이루어진 것을 특징으로 하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법.The negative electrode support layer and the negative electrode functional layer is a nickel (Ni) -based material, characterized in that the reverse voltage degradation phenomenon prevented solid oxide fuel cell manufacturing method.
  4. 제2항에 있어서,The method of claim 2,
    상기 음극 지지층은 니켈 및 YSZ를 포함하고,The cathode support layer comprises nickel and YSZ,
    상기 음극 기능층은 니켈, YSZ 및 세리아를 포함하는 것을 특징으로 하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법.The cathode functional layer is nickel, YSZ and ceria, characterized in that the reverse voltage degradation phenomenon is prevented solid oxide fuel cell manufacturing method.
  5. 제1항에 있어서,The method of claim 1,
    상기 양극층은, The anode layer is,
    상기 전해질층 상에 형성된 양극 기능층(Cathode Functional Layer, CFL); 및 A cathode functional layer (CFL) formed on the electrolyte layer; And
    상기 양극 기능층 상에 형성된 양극 집전층(Current Collector, CC)을 포함하는 것을 특징으로 하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법.And a positive electrode current collector (Current Collector, CC) formed on the positive electrode functional layer, wherein the reverse voltage degradation phenomenon is prevented.
  6. 제5항에 있어서,The method of claim 5,
    상기 양극 기능층은 LSM(Sr-doped LaMnO3) 및 YSZ를 포함하고,The anode functional layer includes SSM (Sr-doped LaMnO 3 ) and YSZ,
    상기 양극 집전층은 LSM을 포함하는 것을 특징으로 하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법.The positive electrode current collector layer comprises a LSM, characterized in that the reverse voltage degradation phenomenon is prevented solid oxide fuel cell manufacturing method.
  7. 제1항에 있어서,The method of claim 1,
    상기 단계 (b)에서 소결에 의해 세륨(cerium) 이온을 음극측에 구비된 세리아를 포함하는 층으로부터 전해질층 내부로 확산시켜 음극 및 전해질층 간의 계면으로부터 전해질층 중심부 측으로 갈수록 세륨 농도가 감소하는 경사 구조(gradient structure)를 형성하는 것을 특징으로 하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법.In the step (b), the cerium ions are diffused into the electrolyte layer from the layer including ceria provided on the cathode side by sintering so that the cerium concentration decreases from the interface between the cathode and the electrolyte layer toward the center of the electrolyte layer. A method for manufacturing a solid oxide fuel cell, in which reverse voltage deterioration is prevented, by forming a gradient structure.
  8. 제1항에 있어서,The method of claim 1,
    상기 단계 (b)에서 1410 내지 1510 ℃의 온도에서 1 내지 11 시간 동안 소결하는 것을 특징으로 하는, 역 전압 열화 현상이 방지된 고체산화물 연료전지의 제조방법.In the step (b), characterized in that the sintering for 1 to 11 hours at a temperature of 1410 to 1510 ℃, a method of manufacturing a solid oxide fuel cell is prevented reverse voltage degradation phenomenon.
  9. 제1항 내지 제8항 중 어느 한 항의 제조방법에 의해 제조된 고체산화물 연료전지 단위 셀.A solid oxide fuel cell unit cell manufactured by the manufacturing method of any one of claims 1 to 8.
  10. 제9항의 단위 셀을 복수 개 포함하는 고체산화물 연료전지 스택.A solid oxide fuel cell stack comprising a plurality of unit cells of claim 9.
PCT/KR2019/008198 2018-07-17 2019-07-04 Method for manufacturing solid oxide fuel cell for preventing degradation under negative cell voltage WO2020017796A1 (en)

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