WO2014119119A1 - Solid oxide fuel cell - Google Patents

Solid oxide fuel cell Download PDF

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Publication number
WO2014119119A1
WO2014119119A1 PCT/JP2013/082411 JP2013082411W WO2014119119A1 WO 2014119119 A1 WO2014119119 A1 WO 2014119119A1 JP 2013082411 W JP2013082411 W JP 2013082411W WO 2014119119 A1 WO2014119119 A1 WO 2014119119A1
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electrolyte
layer
electrode
fuel cell
mixed
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PCT/JP2013/082411
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French (fr)
Japanese (ja)
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矢島　健太郎
宋　東
岩切　保憲
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日産自動車株式会社
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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
    • H01M4/8605—Porous electrodes
    • 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
    • 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

Definitions

  • the present invention relates to a manufacturing technique of a solid oxide fuel cell. More specifically, the present invention can improve the bonding property between an electrode and a solid oxide as an electrolyte, and is indicated as an ohmic resistance factor (hereinafter referred to as “IR resistance”). ) Is reduced and the cell output can be improved.
  • IR resistance ohmic resistance factor
  • a fuel cell is a device that converts chemical energy into electrical energy through an electrochemical reaction.
  • a solid oxide fuel cell (SOFC) which is one of such fuel cells, has a three-layer structure in which layers of a fuel electrode, a solid electrolyte, and an air electrode are stacked in this order. is there. And, as a power generation part of the fuel cell, a fuel gas such as hydrogen or hydrocarbon is supplied from the outside to the fuel electrode, while electricity is generated by supplying an oxidant gas such as air to the air electrode. It has become.
  • a solid electrolyte generally Y 2 O 3 (yttria), Nd 2 O 3 (neodia), Sm 2 O 3 (samaria), Gd 2 O 3 (gadria), Sc 2 O 3 (scandia), etc.
  • stabilized zirconia in which is dissolved, CeO 2 (ceria) -based solid solution, and oxide powder particles such as Bi 2 O 3 and LaGaO 3 are used as materials.
  • What is particularly important in the solid electrolyte layer is the ability to allow ions to pass without passing electrons.
  • oxygen ions are power generation conductors, it is desirable that oxygen ions have a high conductivity. Moreover, it is gas-impermeable.
  • metal powder particles such as Ag (silver) and Pt (platinum) may be used as the air electrode, but generally LaSrMnO (LSM), LaSrCoO (LSC), LaSrCoFeO (LSCF), SmSrCoO ( Oxide powder particles having a perovskite structure represented by SSC), BaSrCoFeO (BSCF), LaNiFeO (LNF) and the like are used.
  • LSM LaSrMnO
  • LSC LaSrCoO
  • LSCF LaSrCoFeO
  • SmSrCoO Oxide powder particles having a perovskite structure represented by SSC
  • LNF LaNiFeO
  • the characteristics necessary for the air electrode include that it is resistant to oxidation, permeates oxidant gas, has high electrical conductivity, and is excellent in catalytic action for converting oxygen molecules into oxygen ions.
  • the fuel electrode includes a noble metal such as Ni (nickel), Co (cobalt), or Pt, or a cermet of Ni and a solid oxide electrolyte such as YSZ (yttria stabilized zirconia) or SDC (samaria doped ceria). Is generally used.
  • a noble metal such as Ni (nickel), Co (cobalt), or Pt
  • a cermet of Ni and a solid oxide electrolyte such as YSZ (yttria stabilized zirconia) or SDC (samaria doped ceria).
  • YSZ yttria stabilized zirconia
  • SDC samaria doped ceria
  • oxygen gas molecules react with electrons at the three-phase interface, which is the active point, and oxygen ions are generated.
  • the oxygen ions are conducted through the solid electrolyte layer to the fuel electrode.
  • oxygen ions conducted from the solid electrolyte layer react with fuel gas molecules to generate electrons.
  • the air electrode and the solid electrolyte, and the fuel electrode and the solid electrolyte are joined in order to ensure reliable oxygen ion conduction characteristics. It is.
  • the thermal expansion coefficients of the solid electrolyte, the air electrode, and the fuel electrode are different at the joint interface between the solid electrolyte, the air electrode, and the fuel electrode, separation occurs due to the difference in thermal expansion during power generation during high temperature operation. There is a risk of reducing the output of the fuel battery cell due to resistance.
  • the electrode In order to increase the adhesion between the electrolyte and the electrode, it is effective to improve the physical bondability between the electrolyte and the electrode. For example, a recess is formed at the electrolyte side interface, By making a part of the electrode enter as an anchor, the electrode can be firmly held.
  • Patent Document 1 As a method of matching the thermal expansion coefficient, it has been proposed to provide a mixed layer made of an electrode material and an electrolyte material at the interface between the electrode and the electrolyte (see Patent Document 1).
  • a vapor deposition process such as pulse laser vapor deposition, sputtering vapor deposition, or chemical vapor deposition. It is described that the film is formed so as not to form a single substance.
  • the film formation by the vapor deposition process has a problem that an electron conductive resistance layer is generated.
  • the cathode electrode air electrode
  • the electrolyte is a single component of Zr, Y, La, Sr, Co, Fe
  • a layer in which a single component of Zr and Y is mixed is formed, and then an electrode and an electrolyte grow on a molecular basis.
  • the electrode and electrolyte crystal grown in molecular units are held in a mixed layer of La, Sr, Co, Fe, Zr, and Y consisting of a single component and coexist in the same particle.
  • a mixed layer in the same particle in which La, Sr, Co, Fe, Zr, and Y are mixed is non-crystalline and becomes a resistance layer of ionic and electronic conduction because of poor crystal purity and crystallinity. For this reason, the ionic conductivity and electronic conductivity between particles are hindered, which causes an increase in IR resistance.
  • the present invention has been made in view of the above-described problems relating to the electrode forming technology of a conventional solid oxide fuel cell, and its object is to provide adhesion between the electrode and the electrolyte even during operation at a high temperature. It is an object of the present invention to provide a solid oxide fuel cell having a low cell resistance and a high cell output.
  • the present inventors formed a mixed layer in the same particle in which the electrode component and the electrolyte component coexist in the same particle between the electrolyte layer and the electrode layer. Without mixing, a mixed layer composed only of electrode component particles and electrolyte component particles was formed.
  • the present invention is based on the above knowledge, and the solid oxide fuel cell of the present invention includes an electrolyte layer and an electrode layer, and includes only electrode component particles and electrolyte component particles at the interface between the electrode layer and the electrolyte layer.
  • the mixed layer is formed, and a part of the mixed layer penetrates into the irregularities on the electrolyte layer side interface.
  • a fuel cell stack of the present invention is formed by stacking the solid oxide fuel cells of the present invention.
  • the mixed layer composed of the electrode component particles and the electrolyte component particles is interposed between the electrolyte layer and the electrode layer of the solid oxide fuel cell, and a part of the mixed layer is uneven on the electrolyte layer side interface. Therefore, the adhesion (bonding) between the electrolyte layer and the electrode layer is improved, the IR resistance is reduced, and the cell output can be increased.
  • FIG. 2 is an enlarged explanatory view conceptually showing an electrolyte layer-electrode layer interface in the solid oxide fuel cell of the present invention. It is explanatory drawing which expands and shows the electrode component particle
  • FIG. 1 It is a graph which shows the density
  • 2 is a scanning electron micrograph of an electrolyte layer-mixed layer interface in a solid oxide fuel cell obtained in Example 1 of the present invention, observed at a high magnification.
  • 2 is a scanning electron micrograph of an electrolyte layer-electrode layer interface in a solid oxide fuel cell obtained in Comparative Example 1.
  • FIG. 2 It is a graph which shows the density
  • the solid oxide fuel cell of the present invention includes an electrolyte material and an electrode material at the interface between the electrolyte layer and the electrode layer, and has an intermediate thermal expansion coefficient between the electrolyte layer and the electrode layer.
  • a layer is formed, and a part of the layer enters the irregularities on the electrolyte layer side interface. Accordingly, the expansion / contraction difference between the electrolyte layer and the electrode layer at the time of temperature increase / decrease is relieved by the mixed layer, and an anchor effect is exerted by allowing a part of the mixed layer to enter the irregularities on the surface of the electrolyte layer. That is, these synergistic effects can maintain the adhesion between the electrode and the electrolyte and reduce the IR resistance even when used at high temperatures.
  • the mixed layer is composed only of electrode component particles and electrolyte component particles, and there is no resistive layer in which the electrolyte material and the electrode material are mixed, so that the ionic conductivity and electronic conductivity of the mixed layer itself are present.
  • the IR resistance of the fuel cell can be further reduced.
  • the thickness may be reduced to about 0.1 to 2 ⁇ m. Desirably, this can suppress a decrease in electrode output density.
  • the thickness of the mixed layer is preferably as thin as possible for the above reasons, it is technically difficult to form a film with a thickness of less than 0.1 ⁇ m.
  • the mixed layer has a composition gradient structure, that is, a structure in which the concentration of the electrolyte component particles is higher on the electrolyte layer side and the concentration of the electrode component particles is higher on the electrode layer side.
  • a composition gradient structure that is, a structure in which the concentration of the electrolyte component particles is higher on the electrolyte layer side and the concentration of the electrode component particles is higher on the electrode layer side.
  • the mixed layer can be produced by a film forming method in which the electrode component particles or the electrode component particles collide with the electrolyte together with the electrolyte component particles. That is, a film forming method is used in which powder electrodes and electrolyte particles are allowed to collide onto the electrolyte by giving an optimum flow rate with a carrier gas such as He or N 2 .
  • the particle diameter of the raw material particles is desirably in the range of about submicron to 5 ⁇ m. If it exceeds 5 ⁇ m, it may be difficult to reduce the thickness of the mixed layer.
  • An example of such a film formation method is a powder jet deposition method. That is, examples of the low temperature film forming method include an aerosol deposition method, examples of the medium temperature film forming method include a warm spray method and a cold spray method, and examples of the high temperature film forming method include a thermal spray method.
  • FIG. 1A the electrode component particles or the mixed particles of the electrode component particles and the electrolyte component particles collide with the electrolyte, and the collision energy at that time
  • a mixed layer 10 of electrode component particles 11 and electrolyte component particles 12 can be formed on the electrolyte 20.
  • the electrolyte surface is scraped to form irregularities, and the scraped electrolyte pieces are mixed with electrodes or electrolyte particles to become part of the mixed layer.
  • FIG. 1 shows an example in which only the electrode component particles 11 are collided, the electrolyte 20 is scraped and scattered by the collision with the particles 11 to form the electrolyte component particles 12 to form the mixed layer 10. Will be.
  • the amorphous layer La is present together with the crystalline layer Lc in the individual electrode component particles 11 and electrolyte component particles 12 formed as shown in FIG.
  • the electrode component and the electrolyte component are not mixed in the amorphous layer La. Therefore, such an amorphous layer La is not a resistance layer for ionic and electronic conduction.
  • the air electrode Ag, Pt, Pd, Rh, Ru, Ni, Co, or (La, Ca) MnO 3 , (La, Sr) MnO 3 is used.
  • a perovskite oxide or a cermet of the above electrode material and electrolyte material can be preferably used.
  • the fuel electrode Ag, Au, Be, C, Si, Fe, Pt, Ir, Cs, Re, Cu simple substance, alloys containing these metals, Cu, Sn, Te, Be, Mg, Co, An alloy of Nb and Ag, an alloy of Ag containing these metals, or a cermet of the above electrode material and electrolyte material can be suitably used.
  • the electrolyte material it is desirable to use a mixture of CeO 2, ZrO 2, TiO 2 , La oxides such as 2 O 3.
  • the solid oxide fuel cell of the present invention can be constituted by stacking a plurality of the fuel cell stacks, and can be a fuel cell stack having high output characteristics stable at high temperatures.
  • an electrolyte layer made of YSZ was formed to a thickness of 5 ⁇ m by a sintering method on a fuel electrode substrate made of NiO—YSZ (yttria stabilized zirconia) and having a thickness of 500 ⁇ m.
  • an air electrode (cathode) made of LSCF was formed on the electrolyte layer made of YSZ by an aerosol deposition method.
  • LSCF fine particles having a particle diameter of 0.8 ⁇ m as electrode component particles were placed on a high-speed He gas flow by a supersonic nozzle and sprayed on the electrolyte layer at a speed of 790 m / s to form an air electrode.
  • the cross-sectional observation of the interface part by a scanning electron microscope was performed.
  • FIG. 4 is an SEM image of the interface portion between the electrolyte layer and the electrode layer (air electrode), in which an air electrode layer composed of LSCF particles is formed on the YSZ electrolyte layer, and between these, the LSCF particles and the YSZ particles. It was confirmed that the mixed layer containing only the intervening layer has a thickness of 1 ⁇ m. Moreover, the LSCF particle diameter (secondary particle) in the completed air electrode, and the LSCF particle diameter and YSZ particle diameter in the mixed layer were approximately 0.1 ⁇ m.
  • FIG. 6 is an electron microscope image obtained by physically peeling the electrode layer after film formation and observing the electrolyte surface after peeling, and it was confirmed that the electrolyte surface was shaved on the unevenness. Furthermore, as a result of observing the electrolyte interface in detail, it was found that a part of the mixed layer entered the recess formed by cutting the electrolyte as shown in FIG.
  • Example 2 A fuel electrode (anode) made of NiO—YSZ was formed on an electrolyte substrate made of YSZ having a thickness of 300 ⁇ m by an aerosol deposition method.
  • the electrode component particles nickel oxide particles having a particle diameter of 1 ⁇ m and YSZ having a particle diameter of 1 ⁇ m mixed at a mass ratio of 70:30 are placed on a high-speed He gas flow by a sonic nozzle, and are 820 m.
  • the fuel electrode was formed to a thickness of about 10 ⁇ m by spraying on the electrolyte substrate at a speed range up to / s.
  • the air electrode was made of LSCF and formed on the back side of the electrolyte substrate by a printing method.
  • a fuel electrode layer composed of NiO and YSZ is formed on the YSZ electrolyte substrate, and a mixed layer (thickness: 1 ⁇ m) containing only fuel electrode component particles (NiO + YSZ) and electrolyte component particles (YSZ) therebetween. ) was confirmed. Further, the particle diameters of NiO and YSZ in the completed fuel electrode layer were both 0.5 ⁇ m. The particle diameters of the fuel electrode component particles and the electrolyte component particles in the mixed layer were approximately 0.1 to 0.2 ⁇ m.
  • the inside of the mixed layer has an inclined structure in which NiO as an electrode component increases as it approaches the electrode layer upward from the interface with the electrolyte layer.
  • the peak of the electrode and the electrolyte was confirmed, and the amorphous mixed layer in the same particle was not confirmed. Further, it has been found that a part of the mixed layer enters as an anchor in the recess formed by cutting the electrolyte substrate.
  • the electrolyte surface was scraped to generate irregularities, and the scraped electrolyte pieces were mixed with electrodes or electrolyte particles to form a mixed layer. It was done.
  • the mixed layer matches the thermal expansion difference between the electrode layer and the electrolyte layer to suppress electrode peeling, and the mixed layer that enters the electrolyte recess creates an anchor effect and improves the adhesion between the electrolyte and the electrode.
  • the thickness of the mixed layer is as very thin as 1 ⁇ m and does not reduce the output density of the electrode.
  • the mixed layer has a composition gradient structure in which the electrode material content increases from the interface with the electrolyte layer toward the electrode surface, and changes in thermal expansion in the mixed layer occur gradually, thus improving the structural stability.
  • the present invention is applied to only one of the air electrode and the fuel electrode.
  • the present invention is not limited to this, and it is desirable to apply to both electrodes.
  • Example 1 Comparative Example 1
  • the air electrode is formed by the same aerosol deposition method on the electrolyte layer (YSZ) formed on the fuel electrode substrate using the same material as in Example 1, the above Example 1 of 720 m / s is used.
  • An air electrode was formed by colliding the fuel electrode component particles at a lower speed.
  • the cross-sectional observation of the interface part of an electrolyte layer and an electrode layer (air electrode) was similarly implemented with the scanning electron microscope.

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Abstract

A mixed layer (10) constituted by only electrode component particles (11) and electrolyte component particles (12) such that an electrode component and an electrolyte component does not coexist in the same particle is formed between an electrolyte layer (20) and an electrode layer (30). The mixed layer (10) is made to intrude into the minute recesses and protrusions of the surface of the electrolyte layer (20).

Description

固体酸化物型燃料電池Solid oxide fuel cell
　本発明は、固体酸化物型燃料電池の製造技術に係り、さらに詳しくは、電極と電解質である固体酸化物との接合性を高めることができ、オーミック抵抗要因（以下「ＩＲ抵抗」と示す。）を減少させて、セル出力を向上させることができる燃料電池に関するものである。 The present invention relates to a manufacturing technique of a solid oxide fuel cell. More specifically, the present invention can improve the bonding property between an electrode and a solid oxide as an electrolyte, and is indicated as an ohmic resistance factor (hereinafter referred to as “IR resistance”). ) Is reduced and the cell output can be improved.
　燃料電池は、化学エネルギーを電気化学的な反応により電気エネルギーに変換する装置である。
　このような燃料電池の１種である固体酸化物型燃料電池（ＳＯＦＣ：Ｓｏｌｉｄ　Ｏｘｉｄｅ　Ｆｕｅｌ　Ｃｅｌｌ）は、燃料極と、固体電解質と、空気極の各層をこの順に積層した３層構造をなすものである。そして、これを燃料電池の発電部として、外部から水素や炭化水素等の燃料ガスを燃料極に供給する一方、空気極には空気等の酸化剤ガスを供給することによって電気を発生させる仕組みとなっている。 A fuel cell is a device that converts chemical energy into electrical energy through an electrochemical reaction.
A solid oxide fuel cell (SOFC), which is one of such fuel cells, has a three-layer structure in which layers of a fuel electrode, a solid electrolyte, and an air electrode are stacked in this order. is there. And, as a power generation part of the fuel cell, a fuel gas such as hydrogen or hydrocarbon is supplied from the outside to the fuel electrode, while electricity is generated by supplying an oxidant gas such as air to the air electrode. It has become.
　ここで、固体電解質としては、一般に、Ｙ２Ｏ３（イットリア）やＮｄ２Ｏ３（ネオジア）、Ｓｍ２Ｏ３（サマリア）、Ｇｄ２Ｏ３（ガドリア）、Ｓｃ２Ｏ３（スカンジア）などを固溶した安定化ジルコニアが用いられる他、ＣｅＯ２（セリア）系固溶体や、Ｂｉ２Ｏ３やＬａＧａＯ３などの酸化物粉末粒子が材料として用いられる。
　固体電解質層において特に重要なことは、電子を通さずにイオンを通す性能であり、酸素イオンが発電の伝導体である場合には、酸素イオンの伝導特性が大きいことが望まれる。また、ガス不透過性であることが挙げられる。 Here, as a solid electrolyte, generally Y 2 O 3 (yttria), Nd 2 O 3 (neodia), Sm 2 O 3 (samaria), Gd 2 O 3 (gadria), Sc 2 O 3 (scandia), etc. In addition, stabilized zirconia in which is dissolved, CeO 2 (ceria) -based solid solution, and oxide powder particles such as Bi 2 O 3 and LaGaO 3 are used as materials.
What is particularly important in the solid electrolyte layer is the ability to allow ions to pass without passing electrons. When oxygen ions are power generation conductors, it is desirable that oxygen ions have a high conductivity. Moreover, it is gas-impermeable.
　一方、空気極としては、Ａｇ（銀）やＰｔ（白金）などの金属系粉末粒子が用いられる場合もあるが、一般には、ＬａＳｒＭｎＯ（ＬＳＭ）やＬａＳｒＣｏＯ（ＬＳＣ）、ＬａＳｒＣｏＦｅＯ（ＬＳＣＦ）、ＳｍＳｒＣｏＯ（ＳＳＣ）、ＢａＳｒＣｏＦｅＯ（ＢＳＣＦ）、ＬａＮｉＦｅＯ（ＬＮＦ）などに代表されるペロブスカイト構造の酸化物粉末粒子が用いられる。
　この空気極に必要な特性としては、酸化に強く、酸化剤ガスを透過し、電気伝導度が高く、酸素分子を酸素イオンに変換する触媒作用に優れていることが挙げられる。 On the other hand, metal powder particles such as Ag (silver) and Pt (platinum) may be used as the air electrode, but generally LaSrMnO (LSM), LaSrCoO (LSC), LaSrCoFeO (LSCF), SmSrCoO ( Oxide powder particles having a perovskite structure represented by SSC), BaSrCoFeO (BSCF), LaNiFeO (LNF) and the like are used.
The characteristics necessary for the air electrode include that it is resistant to oxidation, permeates oxidant gas, has high electrical conductivity, and is excellent in catalytic action for converting oxygen molecules into oxygen ions.
　また、燃料極には、Ｎｉ（ニッケル）やＣｏ（コバルト）、Ｐｔなどの貴金属、あるいはＮｉとＹＳＺ（イットリア安定化ジルコニア）やＳＤＣ（サマリアドープトセリア）などの固体酸化物電解質とのサーメットなどが一般的に用いられる。
　この燃料極に要求される特性としては、還元雰囲気に強く、燃料ガスを透過し、電気伝導度が高く、水素分子をプロトンに変換する触媒作用に優れていることが挙げられる。 Further, the fuel electrode includes a noble metal such as Ni (nickel), Co (cobalt), or Pt, or a cermet of Ni and a solid oxide electrolyte such as YSZ (yttria stabilized zirconia) or SDC (samaria doped ceria). Is generally used.
The characteristics required for this fuel electrode include that it is strong in a reducing atmosphere, permeates the fuel gas, has high electrical conductivity, and has an excellent catalytic action for converting hydrogen molecules into protons.
　すなわち、空気極では、活性点となる三相界面において酸素ガス分子が電子と反応し、酸素イオンが生じ、酸素イオンは固体電解質層を通って燃料極に伝導し、燃料極においては、同じく活性点となる三相界面において、固体電解質層より伝導してきた酸素イオンと燃料ガス分子が反応し、電子が生じる。 That is, at the air electrode, oxygen gas molecules react with electrons at the three-phase interface, which is the active point, and oxygen ions are generated. The oxygen ions are conducted through the solid electrolyte layer to the fuel electrode. At the three-phase interface as a point, oxygen ions conducted from the solid electrolyte layer react with fuel gas molecules to generate electrons.
　さらに、空気極、燃料極と固体電解質層の界面においては、確実な酸素イオンの伝導特性を持たせるためには、空気極と固体電解質、燃料極と固体電解質とが接合されていることが重要である。
　しかし、固体電解質と空気極、燃料極の接合界面において、固体電解質、空気極、燃料極の熱膨張率がそれぞれ異なることから、高温運転となる発電時において、熱膨張差による剥離が生じ、ＩＲ抵抗となり、燃料電池セルの出力を低下させる恐れがある。 Furthermore, at the interface between the air electrode, the fuel electrode, and the solid electrolyte layer, it is important that the air electrode and the solid electrolyte, and the fuel electrode and the solid electrolyte are joined in order to ensure reliable oxygen ion conduction characteristics. It is.
However, since the thermal expansion coefficients of the solid electrolyte, the air electrode, and the fuel electrode are different at the joint interface between the solid electrolyte, the air electrode, and the fuel electrode, separation occurs due to the difference in thermal expansion during power generation during high temperature operation. There is a risk of reducing the output of the fuel battery cell due to resistance.
　電解質と電極間の密着性を上げるためには、電解質と電極との物理的な接合性を向上させることが効果的であり、その一例として、電解質側界面に凹部を形成させて、当該凹部に電極の一部をアンカーとして入り込ませることによって、電極を強固に保持することができる。 In order to increase the adhesion between the electrolyte and the electrode, it is effective to improve the physical bondability between the electrolyte and the electrode. For example, a recess is formed at the electrolyte side interface, By making a part of the electrode enter as an anchor, the electrode can be firmly held.
　一方、熱膨張率を整合する方法としては、電極と電解質の界面に、電極材料と電解質材料からなる混合層を設けることが提案されている（特許文献１参照。）。
　特許文献１では、固体電解質上に形成される空気極層をパルスレーザ蒸着法やスパッタリング蒸着法、化学的気相蒸着法のような蒸着プロセスによって、分子単位で混合されていながら、反応または固溶されて単一物質を形成しないように成膜することが記載されている。 On the other hand, as a method of matching the thermal expansion coefficient, it has been proposed to provide a mixed layer made of an electrode material and an electrolyte material at the interface between the electrode and the electrolyte (see Patent Document 1).
In Patent Document 1, an air electrode layer formed on a solid electrolyte is reacted or dissolved while being mixed in a molecular unit by a vapor deposition process such as pulse laser vapor deposition, sputtering vapor deposition, or chemical vapor deposition. It is described that the film is formed so as not to form a single substance.
日本国特開２０１２－２２１９４６号公報Japanese Unexamined Patent Publication No. 2012-221946
　しかしながら、蒸着プロセスによる成膜では、電子伝導の抵抗層が発生するという課題があった。
　例えば、カソード電極（空気極）をＬａ、Ｓｒ、Ｃｏ、Ｆｅの単一成分、電解質をＺｒ、Ｙの単一成分を用いて成膜する場合、成膜直後にＬａ、Ｓｒ、Ｃｏ、Ｆｅ、Ｚｒ、Ｙの単一成分が混合された層が成膜され、その後、分子単位で電極、電解質が成長する。 However, the film formation by the vapor deposition process has a problem that an electron conductive resistance layer is generated.
For example, when the cathode electrode (air electrode) is formed using a single component of La, Sr, Co, and Fe and the electrolyte is a single component of Zr, Y, La, Sr, Co, Fe, A layer in which a single component of Zr and Y is mixed is formed, and then an electrode and an electrolyte grow on a molecular basis.
　すなわち、単一成分からなるＬａ、Ｓｒ、Ｃｏ、Ｆｅ、Ｚｒ、Ｙの混合層内に、分子単位で成長した電極、電解質結晶が保持されて、同一粒子内に共存する状態となる。このようなＬａ、Ｓｒ、Ｃｏ、Ｆｅ、Ｚｒ、Ｙが混在した同一粒子内の混合層は非結晶であって、結晶純度と結晶性が劣ることからイオン及び電子伝導の抵抗層となる。このため、粒子同士のイオン伝導性、電子伝導性を阻害し、ＩＲ抵抗の増加の要因となる。 That is, the electrode and electrolyte crystal grown in molecular units are held in a mixed layer of La, Sr, Co, Fe, Zr, and Y consisting of a single component and coexist in the same particle. Such a mixed layer in the same particle in which La, Sr, Co, Fe, Zr, and Y are mixed is non-crystalline and becomes a resistance layer of ionic and electronic conduction because of poor crystal purity and crystallinity. For this reason, the ionic conductivity and electronic conductivity between particles are hindered, which causes an increase in IR resistance.
　さらに、電解質凹部に混合層を蒸着プロセスで成膜した場合でも、粒子内部の電極及び電解質と電解質凹部の接触を、同一粒子内の混合層が阻害し、イオン及び電子伝導を妨げてしまう。また、抵抗となる同一粒子内の混合層の生成を抑えるために、電極のみを成膜した場合には、電解質凹部表面と電極粒子の熱膨張差を整合させることができなくなる。
　このように蒸着プロセスでは、ＩＲ抵抗の減少と、熱膨張差の整合を両立させることが難しかった。 Furthermore, even when a mixed layer is formed in the electrolyte recess by a vapor deposition process, the electrode within the particle and the contact between the electrolyte and the electrolyte recess are disturbed by the mixed layer in the same particle, thereby preventing ion and electron conduction. In addition, in the case where only the electrode is formed in order to suppress the generation of the mixed layer in the same particle serving as the resistance, it becomes impossible to match the difference in thermal expansion between the electrolyte recess surface and the electrode particle.
Thus, in the vapor deposition process, it has been difficult to achieve both reduction in IR resistance and matching of thermal expansion differences.
　本発明は、従来の固体酸化物型燃料電池の電極形成技術に関する上記問題に鑑みてなされたものであって、その目的とするところは、高温での作動時においても電極と電解質との密着性を損なうことがなく、ＩＲ抵抗の小さい、セル出力の高い固体酸化物型燃料電池を提供することにある。 The present invention has been made in view of the above-described problems relating to the electrode forming technology of a conventional solid oxide fuel cell, and its object is to provide adhesion between the electrode and the electrolyte even during operation at a high temperature. It is an object of the present invention to provide a solid oxide fuel cell having a low cell resistance and a high cell output.
　本発明者らは、上記目的を達成すべく鋭意検討を重ねた結果、電解質層と電極層の間に、電極成分と電解質成分とが同一粒子内に共存した、同一粒子内の混合層を形成させることなく、電極成分粒子と電解質成分粒子のみから成る混合層を形成させた。 As a result of intensive studies to achieve the above object, the present inventors formed a mixed layer in the same particle in which the electrode component and the electrolyte component coexist in the same particle between the electrolyte layer and the electrode layer. Without mixing, a mixed layer composed only of electrode component particles and electrolyte component particles was formed.
　本発明は上記知見に基づくものであって、本発明の固体酸化物型燃料電池は、電解質層と電極層を備え、電極層の電解質層との界面に、電極成分粒子と電解質成分粒子のみから成る混合層を形成させ、この混合層の一部が電解質層側界面の凹凸内に侵入していることを特徴としている。
　また、本発明の燃料電池スタックは、本発明の上記固体酸化物型燃料電池を積層して成ることを特徴とする。 The present invention is based on the above knowledge, and the solid oxide fuel cell of the present invention includes an electrolyte layer and an electrode layer, and includes only electrode component particles and electrolyte component particles at the interface between the electrode layer and the electrolyte layer. The mixed layer is formed, and a part of the mixed layer penetrates into the irregularities on the electrolyte layer side interface.
In addition, a fuel cell stack of the present invention is formed by stacking the solid oxide fuel cells of the present invention.
　本発明によれば、固体酸化物型燃料電池の電解質層と電極層の間に、電極成分粒子と電解質成分粒子から成る混合層が介在し、この混合層の一部が電解質層側界面の凹凸に入り込んだものとしたから、電解質層と電極層の密着性（接合性）が向上して、ＩＲ抵抗が減少し、セル出力を高めることができる。 According to the present invention, the mixed layer composed of the electrode component particles and the electrolyte component particles is interposed between the electrolyte layer and the electrode layer of the solid oxide fuel cell, and a part of the mixed layer is uneven on the electrolyte layer side interface. Therefore, the adhesion (bonding) between the electrolyte layer and the electrode layer is improved, the IR resistance is reduced, and the cell output can be increased.
（ａ）及び（ｂ）は電極成分粒子を電解質基板に衝突させる成膜法による混合層の成膜要領を概念的に示す説明図である。(A) And (b) is explanatory drawing which shows notionally the film-forming point of the mixed layer by the film-forming method which makes an electrode component particle collide with an electrolyte substrate. 本発明の固体酸化物型燃料電池における電解質層－電極層界面を概念的に示す拡大説明図である。FIG. 2 is an enlarged explanatory view conceptually showing an electrolyte layer-electrode layer interface in the solid oxide fuel cell of the present invention. 図２に示した混合層における電極成分粒子及び電解質成分粒子を拡大して示す説明図である。It is explanatory drawing which expands and shows the electrode component particle | grains and electrolyte component particle | grains in the mixed layer shown in FIG. 本発明の実施例１により得られた固体酸化物型燃料電池における電解質層－電極層界面の走査型電子顕微鏡写真である。2 is a scanning electron micrograph of an electrolyte layer-electrode layer interface in a solid oxide fuel cell obtained in Example 1 of the present invention. 図４のＡ点からＢ点に向けてＥＤＸ線分析を実施した結果として、Ｙ、Ｌａ、Ｓｒの濃度変化を示すグラフである。It is a graph which shows the density | concentration change of Y, La, and Sr as a result of having implemented the EDX ray analysis toward the B point from the A point of FIG. 成膜後の電極層を物理的に剥離した電解質表面の走査型電子顕微鏡画像である。It is the scanning electron microscope image of the electrolyte surface which peeled the electrode layer after film-forming physically. 本発明の実施例１により得られた固体酸化物型燃料電池における電解質層－混合層界面を高倍率で観察した走査型電子顕微鏡写真である。2 is a scanning electron micrograph of an electrolyte layer-mixed layer interface in a solid oxide fuel cell obtained in Example 1 of the present invention, observed at a high magnification. 比較例１により得られた固体酸化物型燃料電池における電解質層－電極層界面の走査型電子顕微鏡写真である。2 is a scanning electron micrograph of an electrolyte layer-electrode layer interface in a solid oxide fuel cell obtained in Comparative Example 1. FIG. 図８のＡ点からＢ点に向けてＥＤＸ線分析を実施した結果として、Ｙ、Ｌａ、Ｓｒの濃度変化を示すグラフである。It is a graph which shows the density | concentration change of Y, La, and Sr as a result of having implemented the EDX ray analysis toward the B point from the A point of FIG. 実施例１により得られた固体酸化物型燃料電池のＩＲ抵抗を比較例１による電池と比較して示すグラフである。2 is a graph showing the IR resistance of a solid oxide fuel cell obtained in Example 1 in comparison with the cell in Comparative Example 1. FIG.
　以下に、本発明の固体酸化物型燃料電池について、さらに詳細、具体的に説明する。なお、本明細書において、「％」は特記しない限り質量百分率を表すものとする。 Hereinafter, the solid oxide fuel cell of the present invention will be described in more detail and specifically. In the present specification, “%” represents mass percentage unless otherwise specified.
　本発明の固体酸化物型燃料電池は、上記したように、電解質層と電極層との界面に、電解質材料と電極材料を含み、電解質層と電極層との中間的な熱膨張率を有する混合層が形成され、その一部が電解質層側界面の凹凸内に入り込んだ構造を有する。
　したがって、昇温、降温時における電解質層と電極層との伸縮差が混合層によって緩和されると共に、混合層の一部を電解質層表面の凹凸に入り込ませたことによるアンカー効果が発揮される。すなわち、これらの相乗効果によって、高温使用時においても、電極と電解質の密着性を保ち、ＩＲ抵抗を減少することができる。 As described above, the solid oxide fuel cell of the present invention includes an electrolyte material and an electrode material at the interface between the electrolyte layer and the electrode layer, and has an intermediate thermal expansion coefficient between the electrolyte layer and the electrode layer. A layer is formed, and a part of the layer enters the irregularities on the electrolyte layer side interface.
Accordingly, the expansion / contraction difference between the electrolyte layer and the electrode layer at the time of temperature increase / decrease is relieved by the mixed layer, and an anchor effect is exerted by allowing a part of the mixed layer to enter the irregularities on the surface of the electrolyte layer. That is, these synergistic effects can maintain the adhesion between the electrode and the electrolyte and reduce the IR resistance even when used at high temperatures.
　また、上記混合層は、電極成分粒子と電解質成分粒子のみから成るものであって、電解質材料と電極材料とが混在する抵抗層が介在しないことから、混合層自体のイオン伝導性、電子伝導性を高めることができ、燃料電池のＩＲ抵抗をさらに一層、低減することができる。 Further, the mixed layer is composed only of electrode component particles and electrolyte component particles, and there is no resistive layer in which the electrolyte material and the electrode material are mixed, so that the ionic conductivity and electronic conductivity of the mixed layer itself are present. The IR resistance of the fuel cell can be further reduced.
　上記混合層は、電解質粒子が混在するため、層の一部で発電に寄与しない部分が生じ、発電への寄与が充分でないことから、その厚さを０．１～２μｍ程度に薄くすることが望ましく、これによって電極出力密度の低下を抑えることができる。
　なお、混合層の厚さは、上記理由により薄いほど好ましいことになるが、０．１μｍ未満に成膜することは、技術的に難しい。 In the mixed layer, since electrolyte particles are mixed, a part of the layer does not contribute to power generation, and the contribution to power generation is not sufficient. Therefore, the thickness may be reduced to about 0.1 to 2 μm. Desirably, this can suppress a decrease in electrode output density.
Although the thickness of the mixed layer is preferably as thin as possible for the above reasons, it is technically difficult to form a film with a thickness of less than 0.1 μm.
　また、上記混合層は、組成傾斜構造、すなわち、電解質層側ほど電解質成分粒子の濃度が高く、電極層側ほど電極成分粒子の濃度が高い構造とすることが望ましい。これによって、混合層内の熱膨張変化が電解質層側では電解質層に近く、電極層側では電極層にちかいものとなるため、密着性がより高まり、構造的安定性が向上する。 Further, it is desirable that the mixed layer has a composition gradient structure, that is, a structure in which the concentration of the electrolyte component particles is higher on the electrolyte layer side and the concentration of the electrode component particles is higher on the electrode layer side. As a result, the change in thermal expansion in the mixed layer is close to the electrolyte layer on the electrolyte layer side and close to the electrode layer on the electrode layer side, so that adhesion is further increased and structural stability is improved.
　本発明の固体酸化物型燃料電池において、上記混合層は、電極成分粒子、あるいは該電極成分粒子を電解質成分粒子と共に、電解質に衝突させる成膜法によって作製することができる。すなわち、粉末状の電極や電解質粒子をＨｅやＮ２などのキャリアガスで最適の流速を持たせ、電解質上に衝突させる成膜法を用いる。このときの原料粒子の粒径は、サブミクロン～５μｍ程度の範囲とすることが望ましい。５μｍを超えると、混合層の薄膜化が困難となることがある。
　このような成膜法としては、パウダージェットデポジション法を挙げることができる。すなわち、低温成膜法としてはエアロゾルデポジション法、中温成膜法としてはウオームスプレー法、コールドスプレー法、高温成膜法としてサーマルスプレー法等を挙げることができる。 In the solid oxide fuel cell of the present invention, the mixed layer can be produced by a film forming method in which the electrode component particles or the electrode component particles collide with the electrolyte together with the electrolyte component particles. That is, a film forming method is used in which powder electrodes and electrolyte particles are allowed to collide onto the electrolyte by giving an optimum flow rate with a carrier gas such as He or N 2 . At this time, the particle diameter of the raw material particles is desirably in the range of about submicron to 5 μm. If it exceeds 5 μm, it may be difficult to reduce the thickness of the mixed layer.
An example of such a film formation method is a powder jet deposition method. That is, examples of the low temperature film forming method include an aerosol deposition method, examples of the medium temperature film forming method include a warm spray method and a cold spray method, and examples of the high temperature film forming method include a thermal spray method.
　すなわち、このようなプロセスにおいては、図１（ａ）に示すように、電極成分粒子、又は電極成分粒子と電解質成分粒子の混合粒子を電解質に衝突させることによって、その際の衝突エネルギーで、図１（ｂ）に示すように、電解質２０の上に、電極成分粒子１１と電解質成分粒子１２の混合層１０を生成させることができる。
　衝突の際、電解質面が削られて凹凸が形成され、さらに削られた電解質片は電極または電解質粒子と混合されて、混合層の一部となる。なお、図１では、電極成分粒子１１のみを衝突させた例を示したが、この粒子１１との衝突によって、電解質２０が削られて飛散し、電解質成分粒子１２となって混合層１０が形成されることになる。 That is, in such a process, as shown in FIG. 1A, the electrode component particles or the mixed particles of the electrode component particles and the electrolyte component particles collide with the electrolyte, and the collision energy at that time As shown in 1 (b), a mixed layer 10 of electrode component particles 11 and electrolyte component particles 12 can be formed on the electrolyte 20.
During the collision, the electrolyte surface is scraped to form irregularities, and the scraped electrolyte pieces are mixed with electrodes or electrolyte particles to become part of the mixed layer. Although FIG. 1 shows an example in which only the electrode component particles 11 are collided, the electrolyte 20 is scraped and scattered by the collision with the particles 11 to form the electrolyte component particles 12 to form the mixed layer 10. Will be.
　また、図２に示すように、混合層１０の一部が成膜の際に削られた電解質基板Ｂの凹凸（図では凹部）に入り込むため、アンカー効果が生じて、電解質層２０と電極層３０の接合性が向上する。
　そして、上記プロセスでは、その成膜特性上、図３に示すように、成膜された個々の電極成分粒子１１や電解質成分粒子１２の内部に、結晶層Ｌｃと共に非結晶層Ｌａが存在したとしても、当該非結晶層Ｌａに電極成分と電解質成分が混在することはない。したがって、このような非結晶層Ｌａはイオン及び電子伝導の抵抗層とはならない。 Further, as shown in FIG. 2, since a part of the mixed layer 10 enters the unevenness (recessed portion in the figure) of the electrolyte substrate B that has been scraped during film formation, an anchor effect occurs, and the electrolyte layer 20 and the electrode layer The bondability of 30 is improved.
In the above process, it is assumed that the amorphous layer La is present together with the crystalline layer Lc in the individual electrode component particles 11 and electrolyte component particles 12 formed as shown in FIG. However, the electrode component and the electrolyte component are not mixed in the amorphous layer La. Therefore, such an amorphous layer La is not a resistance layer for ionic and electronic conduction.
　本発明の固体酸化物型燃料電池における電極材料に関して、空気極としてはＡｇ、Ｐｔ、Ｐｄ、Ｒｈ、Ｒｕ、Ｎｉ、Ｃｏの金属、あるいは（Ｌａ，Ｃａ）ＭｎＯ３、（Ｌａ，Ｓｒ）ＭｎＯ３、（Ｐｒ，Ｓｒ）ＭｎＯ３、（Ｌａ，Ｓｒ）（Ｃｏ，Ｆｅ）Ｏ３、（Ｌａ，Ｓｒ）（Ｍｎ，Ｃｏ）Ｏ３、（Ｌａ，Ｓｒ）（Ｍｎ，Ｃｒ）Ｏ３、（Ｌａ，Ｓｒ）ＣｏＯ３、（Ｌａ，Ｃａ）ＣｏＯ３、ＰｒＣｏＯ３，Ｌａ（Ｎｉ，Ｂｉ）Ｏ３、（Ｉｎ、Ｓｎ）２Ｏ３、（Ｉｎ、Ｚｒ）Ｏ２、ＲｕＯ２／ＺｒＯ２などのペロブスカイト型酸化物、または上記電極材料と電解質材料のサーメットを好適に用いることができる。
　また、燃料極としてはＡｇ、Ａｕ、Ｂｅ、Ｃ、Ｓｉ、Ｆｅ、Ｐｔ、Ｉｒ、Ｃｓ、Ｒｅ、Ｃｕの金属単体、これらの金属を含む合金、Ｃｕ、Ｓｎ、Ｔｅ、Ｂｅ、Ｍｇ、Ｃｏ、ＮｂとＡｇの合金、これらの金属を含むＡｇとの合金、または上記電極材料と電解質材料のサーメットを好適に用いることができる。 Regarding the electrode material in the solid oxide fuel cell of the present invention, as the air electrode, Ag, Pt, Pd, Rh, Ru, Ni, Co, or (La, Ca) MnO 3 , (La, Sr) MnO 3 is used. , (Pr, Sr) MnO 3 , (La, Sr) (Co, Fe) O 3 , (La, Sr) (Mn, Co) O 3 , (La, Sr) (Mn, Cr) O 3 , (La , Sr) CoO 3 , (La, Ca) CoO 3 , PrCoO 3 , La (Ni, Bi) O 3 , (In, Sn) 2 O 3 , (In, Zr) O 2 , RuO 2 / ZrO 2 A perovskite oxide or a cermet of the above electrode material and electrolyte material can be preferably used.
In addition, as the fuel electrode, Ag, Au, Be, C, Si, Fe, Pt, Ir, Cs, Re, Cu simple substance, alloys containing these metals, Cu, Sn, Te, Be, Mg, Co, An alloy of Nb and Ag, an alloy of Ag containing these metals, or a cermet of the above electrode material and electrolyte material can be suitably used.
　一方、電解質材料としては、ＣｅＯ２、ＺｒＯ２、ＴｉＯ２、Ｌａ２Ｏ３等の酸化物の混合体を用いることが望ましい。 Meanwhile, as the electrolyte material, it is desirable to use a mixture of CeO 2, ZrO 2, TiO 2 , La oxides such as 2 O 3.
　本発明の固体酸化物型燃料電池は、その複数個を積層することによって燃料電池スタックを構成することができ、高温で安定した高出力特性の燃料電池スタックとすることができる。 The solid oxide fuel cell of the present invention can be constituted by stacking a plurality of the fuel cell stacks, and can be a fuel cell stack having high output characteristics stable at high temperatures.
　以下、本発明を実施例に基づいて、具体的に説明するが、本発明はこのような実施例によって何ら限定されることはない。 Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to the examples.
（実施例１）
　まず、ＮｉＯ－ＹＳＺ（イットリア安定化ジルコニア）から成る厚さ５００μｍの燃料極基板上に、焼結法によってＹＳＺから成る電解質層を５μｍの厚さに形成した。 (Example 1)
First, an electrolyte layer made of YSZ was formed to a thickness of 5 μm by a sintering method on a fuel electrode substrate made of NiO—YSZ (yttria stabilized zirconia) and having a thickness of 500 μm.
　次いで、ＹＳＺから成る電解質層の上に、エアロゾルデポジション法によりＬＳＣＦから成る空気極（カソード）を成膜した。
　電極成分粒子として粒径０．８μｍのＬＳＣＦ微細粒子を超音速ノズルによって、高速のＨｅガス流に乗せて、７９０ｍ／ｓの速度で、電解質層に吹き付けることにより空気極を形成した。そして、空気極の成膜後、走査型電子顕微鏡による界面部分の断面観察を行った。 Next, an air electrode (cathode) made of LSCF was formed on the electrolyte layer made of YSZ by an aerosol deposition method.
LSCF fine particles having a particle diameter of 0.8 μm as electrode component particles were placed on a high-speed He gas flow by a supersonic nozzle and sprayed on the electrolyte layer at a speed of 790 m / s to form an air electrode. And after film-forming of an air electrode, the cross-sectional observation of the interface part by a scanning electron microscope was performed.
　図４は、電解質層と電極層（空気極）の界面部分のＳＥＭ像であって、ＹＳＺ電解質層の上にＬＳＣＦ粒子から成る空気極層が形成され、これらの間に、ＬＳＣＦ粒子とＹＳＺ粒子のみを含む混合層が１μｍの厚さに介在していることが確認された。
　また、完成した空気極におけるＬＳＣＦ粒子径（２次粒子）、及び混合層におけるＬＳＣＦ粒子径、ＹＳＺ粒子径は、概ね０．１μｍであった。 FIG. 4 is an SEM image of the interface portion between the electrolyte layer and the electrode layer (air electrode), in which an air electrode layer composed of LSCF particles is formed on the YSZ electrolyte layer, and between these, the LSCF particles and the YSZ particles. It was confirmed that the mixed layer containing only the intervening layer has a thickness of 1 μm.
Moreover, the LSCF particle diameter (secondary particle) in the completed air electrode, and the LSCF particle diameter and YSZ particle diameter in the mixed layer were approximately 0.1 μm.
　さらに、図４中のＡ点からＢ点に向けて、ＥＤＸ線分析を実施した。
　その結果、図５に示すように、電解質層と電極層の間に、電極成分であるＬａ、Ｓｒ、電解質成分のＹが混合された混合層が確認され、混合層内は、電解質層との界面から上方に向かって電極層に近づくほど、Ｌａ、Ｓｒの電極成分が増加する傾斜構造であることが確認された。 Further, EDX ray analysis was performed from point A to point B in FIG.
As a result, as shown in FIG. 5, a mixed layer in which La and Sr as electrode components and Y as the electrolyte component are mixed is confirmed between the electrolyte layer and the electrode layer. It was confirmed that the structure is an inclined structure in which the electrode components of La and Sr increase as it approaches the electrode layer upward from the interface.
　図６は、成膜後の電極層を物理的に剥離し、剥離後の電解質面を観察した電子顕微鏡画像であって、電解質表面が凹凸上に削られていることが確認された。
　さらに、電解質界面を詳細に観察した結果、図７に示すように、電解質が削られて形成された凹部に、混合層の一部が入り込んでいることが判明した。 FIG. 6 is an electron microscope image obtained by physically peeling the electrode layer after film formation and observing the electrolyte surface after peeling, and it was confirmed that the electrolyte surface was shaved on the unevenness.
Furthermore, as a result of observing the electrolyte interface in detail, it was found that a part of the mixed layer entered the recess formed by cutting the electrolyte as shown in FIG.
（実施例２）
　厚さ３００μｍのＹＳＺから成る電解質基板に、ＮｉＯ－ＹＳＺから成る燃料極（アノード）をエアロゾルデポジション法により成膜した。
　電極成分粒子としては、粒径１μｍの酸化ニッケル粒子と、同じく粒径１μｍのＹＳＺとを７０：３０の質量比で混合したものを用い、音速ノズルによって、高速のＨｅガス流に乗せて、８２０ｍ／ｓまでの速度範囲で、電解質基板に吹き付けることにより、燃料極を１０μｍ程度の厚さに成膜した。なお、空気極については、ＬＳＣＦから成るものとし、印刷法によって電解質基板の裏面側に形成した。 (Example 2)
A fuel electrode (anode) made of NiO—YSZ was formed on an electrolyte substrate made of YSZ having a thickness of 300 μm by an aerosol deposition method.
As the electrode component particles, nickel oxide particles having a particle diameter of 1 μm and YSZ having a particle diameter of 1 μm mixed at a mass ratio of 70:30 are placed on a high-speed He gas flow by a sonic nozzle, and are 820 m. The fuel electrode was formed to a thickness of about 10 μm by spraying on the electrolyte substrate at a speed range up to / s. The air electrode was made of LSCF and formed on the back side of the electrolyte substrate by a printing method.
　この結果、ＹＳＺ電解質基板の上にＮｉＯとＹＳＺから成る燃料極層が形成され、これらの間に、燃料極成分粒子（ＮｉＯ＋ＹＳＺ）と電解質成分粒子（ＹＳＺ）のみを含む混合層（厚さ：１μｍ）が介在していることが確認された。
　また、完成した燃料極層おけるＮｉＯ及びＹＳＺの粒子径は、いずれも０．５μｍであった。そして、混合層における燃料極成分粒子及び電解質成分粒子の粒径は概ね０．１～０．２μｍであった。 As a result, a fuel electrode layer composed of NiO and YSZ is formed on the YSZ electrolyte substrate, and a mixed layer (thickness: 1 μm) containing only fuel electrode component particles (NiO + YSZ) and electrolyte component particles (YSZ) therebetween. ) Was confirmed.
Further, the particle diameters of NiO and YSZ in the completed fuel electrode layer were both 0.5 μm. The particle diameters of the fuel electrode component particles and the electrolyte component particles in the mixed layer were approximately 0.1 to 0.2 μm.
　さらに、ＥＤＸ線分析を同様に実施した結果、混合層内は、電解質層との界面から上方に向かって電極層に近づくほど、電極成分であるＮｉＯが増加する傾斜構造であることが確認された。
　そして、混合層のＸＲＤ分析では、電極及び電解質のピークが確認され、同一粒子内の非結晶混合層は確認されなかった。
　また、電解質基板が削られて形成された凹部に、混合層の一部がアンカーとして入り込んでいることが判明した。 Furthermore, as a result of conducting EDX ray analysis in the same manner, it was confirmed that the inside of the mixed layer has an inclined structure in which NiO as an electrode component increases as it approaches the electrode layer upward from the interface with the electrolyte layer. .
And in the XRD analysis of the mixed layer, the peak of the electrode and the electrolyte was confirmed, and the amorphous mixed layer in the same particle was not confirmed.
Further, it has been found that a part of the mixed layer enters as an anchor in the recess formed by cutting the electrolyte substrate.
　上記のように、エアロゾルデポジション法によれば、電解質面が削られて凹凸が生成され、さらに削られた電解質片は電極又は電解質粒子と混合されて、混合層を形成していたことが確認された。
　そして、混合層によって、電極層と電解質層の熱膨張差を整合させて電極剥離を抑制し、電解質凹部に入った混合層はアンカー効果を生み出して、電解質と電極の密着性を向上させている。そして混合層の厚さは１μmと非常に薄く、電極の出力密度を低減させる事はない。 As described above, according to the aerosol deposition method, it was confirmed that the electrolyte surface was scraped to generate irregularities, and the scraped electrolyte pieces were mixed with electrodes or electrolyte particles to form a mixed layer. It was done.
The mixed layer matches the thermal expansion difference between the electrode layer and the electrolyte layer to suppress electrode peeling, and the mixed layer that enters the electrolyte recess creates an anchor effect and improves the adhesion between the electrolyte and the electrode. . The thickness of the mixed layer is as very thin as 1 μm and does not reduce the output density of the electrode.
　また、混合層は、電解質層との界面から電極表面に向かうほど、電極物質含量が増加する組成傾斜構造であり、混合層内の熱膨張変化が漸進的に起こるので、構造的安定性が向上しており、これらの効果によって、電極剥離を抑制し、高温での性能安定化を図ることができる。 In addition, the mixed layer has a composition gradient structure in which the electrode material content increases from the interface with the electrolyte layer toward the electrode surface, and changes in thermal expansion in the mixed layer occur gradually, thus improving the structural stability. These effects can suppress electrode peeling and stabilize the performance at high temperatures.
　なお、上記実施例１及び２においては、いずれも空気極及び燃料極の一方だけをエアロゾルデポジション法によって形成した例を示したが、本発明は、空気極及び燃料極の一方だけに適用することに限定される訳ではなく、両電極双方に適用することが望ましいことは言うまでもない。 In the first and second embodiments, an example in which only one of the air electrode and the fuel electrode is formed by the aerosol deposition method is shown. However, the present invention is applied to only one of the air electrode and the fuel electrode. Of course, the present invention is not limited to this, and it is desirable to apply to both electrodes.
（比較例１）
　実施例１と同様の材料を用いて、燃料極基板上に形成された電解質層（ＹＳＺ）の上に、同様のエアロゾルデポジション法によって空気極を形成するに際して、７２０ｍ／ｓという上記実施例１より低速度で燃料極成分粒子を衝突させて空気極を成膜した。
　そして、成膜後、走査型電子顕微鏡によって、電解質層と電極層（空気極）との界面部分の断面観察を同様に実施した。 (Comparative Example 1)
When the air electrode is formed by the same aerosol deposition method on the electrolyte layer (YSZ) formed on the fuel electrode substrate using the same material as in Example 1, the above Example 1 of 720 m / s is used. An air electrode was formed by colliding the fuel electrode component particles at a lower speed.
And after film-forming, the cross-sectional observation of the interface part of an electrolyte layer and an electrode layer (air electrode) was similarly implemented with the scanning electron microscope.
　その結果、図８に示すように、空気極は成膜されたものの、衝突エネルギーが不足したことによって、図９に示すように混合層が生成しておらず、界面での接合が不十分となった。
　また、得られた燃料電池のＩＲ抵抗を上記実施例１により得られた電池と比較した結果、実施例１による燃料電池の２倍近くに増加していることが判明した。 As a result, as shown in FIG. 8, although the air electrode was formed, the mixed energy was not generated as shown in FIG. 9 due to insufficient collision energy, and the bonding at the interface was insufficient. became.
Further, as a result of comparing the IR resistance of the obtained fuel cell with that of the cell obtained in Example 1, it was found that the fuel cell increased nearly twice that of the fuel cell in Example 1.
　以上、本発明を若干の実施形態及び実施例によって説明したが、本発明はこれらに限定されるものではなく、本発明の要旨の範囲内で種々の変形が可能である。 As mentioned above, although this invention was demonstrated by some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention.
　日本国特願２０１３－０１５０３９号（出願日：２０１３年１月３０日）の全内容は、ここに援用される。 The entire contents of Japanese Patent Application No. 2013-015039 (filing date: January 30, 2013) are incorporated herein by reference.
　１０　混合層
　１１　電極成分粒子
　１２　電解質成分粒子
　２０　電解質（層）
　３０　電極層 10 Mixed Layer 11 Electrode Component Particle 12 Electrolyte Component Particle 20 Electrolyte (Layer)
30 electrode layer

Claims (5)

  1. 　電解質層と電極層を備えた固体酸化物型燃料電池であって、電極層の電解質層との界面に、電極成分粒子と電解質成分粒子から成る混合層が形成され、該混合層の一部が電解質層側界面の凹凸内に侵入していることを特徴とする固体酸化物型燃料電池。 A solid oxide fuel cell comprising an electrolyte layer and an electrode layer, wherein a mixed layer comprising electrode component particles and electrolyte component particles is formed at an interface between the electrode layer and the electrolyte layer, and a part of the mixed layer is formed A solid oxide fuel cell characterized in that it penetrates into irregularities on the electrolyte layer side interface.
  2. 　上記混合層の厚さが０．１～２μｍの範囲であることを特徴とする請求項１に記載の固体酸化物型燃料電池。 2. The solid oxide fuel cell according to claim 1, wherein the mixed layer has a thickness in the range of 0.1 to 2 μm.
  3. 　上記混合層が電解質層と接触している面から電極層側に向けて電極成分粒子の含有量が増加する組成傾斜構造をなしていることを特徴とする請求項１又は２に記載の固体酸化物型燃料電池。 3. The solid oxidation according to claim 1, wherein the mixed layer has a composition gradient structure in which the content of electrode component particles increases from the surface in contact with the electrolyte layer toward the electrode layer side. Physical fuel cell.
  4. 　上記混合層が電極成分粒子又は電極成分粒子と電解質成分粒子の混合粒子体を電解質層に衝突させる成膜法により製造されていることを特徴とする請求項１～３のいずれか１つ項に記載の固体酸化物型燃料電池。 The mixed layer according to any one of claims 1 to 3, wherein the mixed layer is manufactured by a film forming method in which electrode component particles or a mixed particle body of electrode component particles and electrolyte component particles collides with the electrolyte layer. The solid oxide fuel cell described.
  5. 　請求項１～４のいずれか１つの項に記載の固体酸化物型燃料電池を積層して成ることを特徴とする燃料電池スタック。 A fuel cell stack, comprising a stack of the solid oxide fuel cells according to any one of claims 1 to 4.
PCT/JP2013/082411 2013-01-30 2013-12-03 Solid oxide fuel cell WO2014119119A1 (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01227362A (en) * 1988-03-04 1989-09-11 Mitsubishi Heavy Ind Ltd Manufacture of solid electrolyte fuel cell
JP2005339986A (en) * 2004-05-27 2005-12-08 Fuji Photo Film Co Ltd Solid oxide fuel cell and manufacturing method thereof
JP2006079889A (en) * 2004-09-08 2006-03-23 Toyota Motor Corp Manufacturing method of electrolyte-electrode junction and fuel cell
JP2006079888A (en) * 2004-09-08 2006-03-23 Toyota Motor Corp Manufacturing method of fuel cell and fuel cell
JP2006252826A (en) * 2005-03-08 2006-09-21 Toyota Motor Corp Manufacturing method of fuel cell
JP2011181262A (en) * 2010-02-26 2011-09-15 Kyocera Corp Solid-oxide fuel cell

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01227362A (en) * 1988-03-04 1989-09-11 Mitsubishi Heavy Ind Ltd Manufacture of solid electrolyte fuel cell
JP2005339986A (en) * 2004-05-27 2005-12-08 Fuji Photo Film Co Ltd Solid oxide fuel cell and manufacturing method thereof
JP2006079889A (en) * 2004-09-08 2006-03-23 Toyota Motor Corp Manufacturing method of electrolyte-electrode junction and fuel cell
JP2006079888A (en) * 2004-09-08 2006-03-23 Toyota Motor Corp Manufacturing method of fuel cell and fuel cell
JP2006252826A (en) * 2005-03-08 2006-09-21 Toyota Motor Corp Manufacturing method of fuel cell
JP2011181262A (en) * 2010-02-26 2011-09-15 Kyocera Corp Solid-oxide fuel cell

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