Sintered body for electrode and manufacturing method of sintered body for electrode

Abstract

To provide a sintered body which, when applied to an electrode of a SOFC or SOEC, allows for easy attachment of an external connection terminal and easy formation of a metal seal.SOLUTION: A sintered body for an electrode of a SOFC or SOEC includes an oxide-ion conductive solid electrolyte and a metal, the metal includes at least one of Fe, Ni, and Cu, a volume ratio of the metal to the oxide-ion conductive solid electrolyte is in the range of 10:90 to 20:80, and when a cross section of the sintered body is observed over an area of 500 μm×500 μm, metal particles having a maximum dimension of less than 100 μm account for 80% or more of all the metal particles.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a sintered body for an electrode and a method for manufacturing the sintered body for an electrode.

Background Art

[0002] In recent years, from the perspective of the spread of renewable energy, as one of the implementation forms of the technical concept of Power to Gas / Chemical, a high-efficiency energy system combining a solid oxide fuel cell (SOFC) and a solid oxide electrolysis cell (SOEC) has attracted attention.

[0003] Both the solid oxide fuel cell (SOFC) and the solid oxide electrolysis cell (SOEC) are electrochemical cells that operate at high temperatures. The former can handle various fuels such as hydrogen, carbon monoxide, and methane, and the latter can electrolyze water and carbon dioxide generated by the operation of the SOFC and return them to hydrogen and carbon monoxide.

[0004] The SOFC and the SOEC have a solid electrolyte layer provided between two electrodes (fuel electrode and oxygen electrode), and operate by the conduction of oxide ions through this solid electrolyte layer.

[0005] In the SOFC and the SOEC, the support structure of the cell is roughly classified into three types: an electrolyte-supported type, a fuel electrode-supported type, and a metal plate-supported type.

[0006] Among these, in the electrolyte-supported type structure, the solid electrolyte layer functions as a support for other members, a first electrode is disposed on one side of the solid electrolyte layer, and a second electrode is disposed on the other side. In the fuel electrode-supported type structure, the fuel electrode functions as a support for other members, and the solid electrolyte layer and the oxygen electrode are disposed on one side of the fuel electrode. In the metal plate-supported type structure, the fuel electrode, the solid electrolyte layer, and the oxygen electrode are installed on one side of the metal porous plate.

Prior Art Documents

Patent Documents

[0007] [Non-Patent Document 1] Selmar de Souza et al 1997 J.Electrochem.Soc. 144 L35 [Summary of the Invention] [Problems to be Solved by the Invention]

[0008] In a fuel electrode supported structure, an oxide such as nickel oxide is used as a support of a cell member. The oxide of the support is reduced before use and converted into a metal electrode after the remaining cell members are arranged on the upper part.

[0009] In a fuel electrode supported structure, the first support is in the form of an oxide and has no conductivity.

[0010] Therefore, in a fuel electrode supported structure, it is not easy to attach a conductor such as an external connection terminal to the support. Also, for the same reason, in a fuel electrode supported structure, it is not easy to form a seal member made of metal to block the cell from the external environment or prevent the mixing of gases on the fuel electrode side and the oxygen electrode side.

[0011] Against such a background, a support structure that can easily attach a conductor and can easily form a seal structure is desired.

[0012] Note that in the above-described metal plate supported structure, since a metal plate is used as a support, the above-described problems are less likely to occur. That is, in the metal plate supported structure, an external connection terminal can be joined to the side opposite to the side where the cell member of the support plate is arranged by using a welding method or the like. Also, a metal seal can be easily formed by utilizing the periphery of the support which is a conductor.

[0013] However, in the metal plate supported structure, an oxide for a fuel electrode is arranged on the metal support during assembly.

[0014] As described above, before the cell is used, the fuel electrode is in the form of an oxide, and the joint between the metal support and the fuel electrode is a joint of dissimilar materials. Therefore, in the metal plate-supported structure, there is a problem that the joint property between the support and the fuel electrode cannot be enhanced so much. Further, in the case of joining dissimilar materials, when heat is applied to the assembly, peeling may occur at the interface due to the difference in the coefficient of thermal expansion.

[0015] As described above, in the conventional technology, problems can occur in both the fuel electrode-supported structure and the metal plate-supported structure.

[0016] The present invention has been made in view of such a background. In the present invention, when applied to the electrodes of SOFC or SOEC, an external connection terminal can be easily attached, and a sintered body capable of easily forming a metal seal is provided. Another object of the present invention is to provide a method for manufacturing such a sintered body.

Means for Solving the Problems

[0017] In the present invention, there is provided a sintered body for an electrode of SOFC or SOEC, which contains an oxide ion-conductive solid electrolyte and a metal, wherein the metal contains at least one of Fe, Ni, and Cu, the volume ratio of the metal to the oxide ion-conductive solid electrolyte is in the range of 10:90 to 20:80, and when the cross-section of the sintered body is observed in a region of 500 μm × 500 μm, a sintered body is provided in which metal particles having a maximum dimension of less than 100 μm occupy 80% or more of the total metal particles.

[0018] Further, in the present invention, there is provided a method for manufacturing a sintered body for an electrode of SOFC or SOEC, (1) Prepare a mixed powder containing a metal powder and an oxide ion-conductive solid electrolyte powder, where the metal contains at least one of Fe, Ni, and Cu, the volume ratio of the metal to the oxide ion-conductive solid electrolyte is in the range of 10:90 to 20:80, (2) A method is provided in which the mixed powder is sintered using a discharge plasma method to obtain a sintered body.

Advantages of the Invention

[0019] In the present invention, when applied to the electrodes of SOFC or SOEC, a sintered body can be provided that enables easy attachment of external connection terminals and easy formation of a metal seal. Further, in the present invention, a method for manufacturing such a sintered body can be provided.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0021] Hereinafter, an embodiment of the present invention will be described.

[0022] As described above, in the fuel electrode-supported structure, the initial support is in the form of an oxide and has no conductivity. For this reason, in the fuel electrode-supported structure, it is not easy to attach a conductor to the support or form a metal seal around it.

[0023] In addition, in the metal plate-supported structure, during assembly, the oxide for the fuel electrode is disposed on the metal support. For this reason, in the metal plate-supported structure, the joining between the metal support and the fuel electrode is a joining of dissimilar materials, and there is a problem that the joinability between the support and the fuel electrode cannot be enhanced very much. Further, in the case of joining dissimilar materials, when heat is applied to the assembly, peeling may occur at the interface due to the difference in the coefficient of thermal expansion.

[0024] On the other hand, in one embodiment of the present invention, there is provided a sintered body for an electrode of an SOFC or an SOEC, containing an oxide ion-conductive solid electrolyte and a metal, wherein the metal contains at least one of Fe, Ni, and Cu, the volume ratio of the metal to the oxide ion-conductive solid electrolyte is in the range of 10:90 to 20:80, and when the cross-section of the sintered body is observed in a region of 500 μm × 500 μm, there is provided a sintered body in which metal particles having a maximum size of less than 100 μm occupy 80% or more of the total metal particles.

[0025] The sintered body according to one embodiment of the present invention contains an oxide ion-conductive solid electrolyte and a metal.

[0026] Further, in one embodiment of the present invention, the metal contained in the sintered body is uniformly dispersed throughout the sintered body. Specifically, in one embodiment of the present invention, when the cross-section of the sintered body is observed in a region of 500 μm × 500 μm, it is characterized in that metal particles having a maximum size of less than 100 μm are 80% or more of the total metal particles.

[0027] Here, the "maximum size" of the metal particles means the maximum length of the target metal particles. For example, when a plurality of metal particles are connected to form a larger single metal particle, the "maximum size" represents the maximum length of this single metal particle. Therefore, when a sintered body is manufactured using metal particles of the same size as a raw material, it can be said that the smaller the "maximum size" of the metal particles, the more uniformly the metal particles are dispersed.

[0028] In the sintered body according to an embodiment of the present invention, the metal components are uniformly dispersed throughout, and the sintered body has good conductivity. For example, the sintered body according to an embodiment of the present invention has a conductivity of 50 S / cm or more at room temperature.

[0029] Therefore, an external connection terminal can be easily attached to the sintered body according to an embodiment of the present invention, for example, by a welding method or the like. Further, in the sintered body according to an embodiment of the present invention, it is also easy to use a metal for the seal structure surrounding the cell member.

[0030] Due to the above effects, the sintered body according to an embodiment of the present invention can be suitably applied to the electrodes of a fuel electrode-supported type structure.

[0031] (Sintered body according to an embodiment of the present invention) Next, the characteristics of the sintered body according to an embodiment of the present invention will be described in more detail.

[0032] The sintered body according to an embodiment of the present invention has an oxide ion conductive solid electrolyte and a metal.

[0033] (Oxide ion conductive solid electrolyte) The solid electrolyte contained in the sintered body according to an embodiment of the present invention is not particularly limited as long as it has oxide ion conductivity.

[0034] The solid electrolyte is selected from the group consisting of, for example, YSZ (yttrium-doped zirconia), GDC (gadolinium-doped ceria), and mayenite compounds.

[0035] In the present application, the mayenite compound means a substance having a crystal structure of the C12A7 (12CaO·7Al2O3) type and having a characteristic crystal structure with three-dimensionally connected voids (cages).

[0036] The framework that constitutes the cage of the mayenite compound is positively charged and contains 12 cage structures per unit cell. For a stoichiometric representative substance, 1 / 6 of this cage encloses oxide ions inside to satisfy the electrical neutrality condition of the crystal. The oxide ions in this cage are chemically bonded loosely compared to other oxide ions that make up the crystal framework, and are thus particularly called free oxide ions.

[0037] Typical materials of the mayenite compound are, for example, 12CaO·7Al2O3, 12SrO·7Al2O3, and 12MgO·7Al2O3. However, in these materials, some of the cations (Ca, Al, Sr, and Mg) may be replaced by other cations respectively.

[0038] Therefore, in the present application, materials in which some of such cations are replaced by other cations are also referred to as mayenite compounds.

[0039] (metal) The metal contained in the sintered body according to one embodiment of the present invention includes at least one of Fe, Ni, and Cu. In particular, it is preferable that Ni is contained in the sintered body according to one embodiment of the present invention.

[0040] In the sintered body according to one embodiment of the present invention, the volume ratio of the metal to the oxide ion conductive solid electrolyte is in the range of 10:90 to 20:80.

[0041] In the sintered body according to one embodiment of the present invention, when the ratio (volume ratio) of the metal to the oxide ion conductive solid electrolyte is less than 10 / 90, good conductivity will not be exhibited in the sintered body. Also, when the ratio (volume ratio) of the metal to the oxide ion conductive solid electrolyte exceeds 20 / 80, the oxide ion conductivity decreases and the function as an electrode becomes insufficient.

[0042] In the sintered body according to one embodiment of the present invention, the content of the metal is preferably less than 50% by weight.

[0043] (sintered body) When observing the sintered body according to an embodiment of the present invention in a region with a cross-section of 500 μm × 500 μm, metal particles with a maximum dimension of less than 100 μm account for 80% or more of the total metal particles.

[0044] When the proportion of metal particles with a maximum dimension of less than 100 μm is less than 80% of the total metal particles, the conductivity of the sintered body may decrease.

[0045] The sintered body according to an embodiment of the present invention can be applied to the electrodes of SOFC and SOEC having a fuel electrode support type structure.

[0046] FIG. 1 schematically shows a configuration example of an SOFC cell.

[0047] As shown in FIG. 1, the SOFC cell 100 has an oxygen electrode 110, a fuel electrode 120, and a solid electrolyte layer 130 between both electrodes.

[0048] At the oxygen electrode 110, for example, the following reaction occurs: O2 + 4e - → 2O 2- (Equation (1)) The oxide ions generated at the oxygen electrode 110 pass through the solid electrolyte layer 130 and reach the opposite fuel electrode 120. At the fuel electrode 120, for example, the following reaction occurs: 2H2 + 2O 2- → 2H2O + 4e - (Equation (2)) Therefore, when the SOFC cell 100 is connected to an external load 140, the reactions of Equation (1) and Equation (2) continue, and power can be supplied to the external load 140.

[0049] The SOFC cell 100 shown in FIG. 1 has a fuel electrode support type structure. That is, in the SOFC cell 100, the fuel electrode 120 has a form that supports the solid electrolyte layer 130 and the oxygen electrode 110.

[0050] In such a SOFC cell 100, when the sintered body according to an embodiment of the present invention is applied to the fuel electrode 120, the problems of the fuel electrode supported type structure as described above can be significantly solved or reduced.

[0051] That is, since the sintered body according to an embodiment of the present invention has good conductivity, an external connection terminal can be easily attached to a part of the fuel electrode 120, for example, by a welding method or the like. Further, in the sintered body according to an embodiment of the present invention, a metal seal structure surrounding the oxygen electrode 110 and the solid electrolyte layer 130 can be constructed relatively easily.

[0052] FIG. 2 schematically shows an example of the configuration of a SOFC having a seal structure.

[0053] As shown in FIG. 2, in this example, a seal structure 150 is constructed around the SOFC 100.

[0054] Specifically, a cylindrical seal structure 150 is configured by disposing a metal seal member 170 between the fuel electrode 120 of the circular SOFC 100 and the housing 160.

[0055] When the fuel electrode 120 is formed of the sintered body according to an embodiment of the present invention, the fuel electrode 120 and the seal member 170 can be welded using the side surface of the fuel electrode 120.

[0056] Therefore, in the sintered body according to an embodiment of the present invention, it is possible to easily construct the seal structure 150 using such a metal seal member 170.

[0057] On the other hand, FIG. 3 schematically shows an example of the configuration of a SOEC cell.

[0058] As shown in FIG. 3, the SOEC cell 200 has an oxygen electrode 210, a fuel electrode 220, and a solid electrolyte layer 230 between both electrodes.

[0059] In the oxygen electrode 210, for example, the following reaction occurs: 2O 2- →O2 + 4e - (Equation (3)) Also, at the fuel electrode 220, for example, the following reaction occurs: 2H2O + 4e - →2H2 + 2O 2- (Equation (4)) The oxide ions generated at the fuel electrode 220 pass through the solid electrolyte layer 230 and reach the opposite oxygen electrode 210. Therefore, when the SOEC cell 200 is connected to the external power source 240, the reactions of Equation (3) and Equation (4) continue.

[0060] In such an SOEC cell 200, when the sintered body according to an embodiment of the present invention is applied to the fuel electrode 220, the problems of the fuel electrode-supported structure as described above can be significantly solved or reduced.

[0061] That is, since the sintered body according to an embodiment of the present invention has good conductivity, an external connection terminal can be easily attached to a part of the fuel electrode 220, for example, by a welding method or the like. Further, in the sintered body according to an embodiment of the present invention, a metal seal member can be used in the seal structure surrounding the oxygen electrode 210 and the solid electrolyte layer 230.

[0062] (Method for manufacturing a sintered body according to an embodiment of the present invention) Next, with reference to FIG. 4, a method for manufacturing a sintered body according to an embodiment of the present invention will be described.

[0063] FIG. 4 schematically shows an example of the flow of a method for manufacturing a sintered body according to an embodiment of the present invention (hereinafter referred to as the "first method").

[0064] As shown in FIG. 4, the first method includes (1) a step of preparing a mixed powder containing a metal powder and a powder of an oxide ion-conductive solid electrolyte (step S110), (2) Sintering the mixed powder using a discharge plasma method to obtain a sintered body (step S120); It has.

[0065] Hereinafter, each step will be described.

[0066] (Step S110) First, the mixed powder is formulated.

[0067] The mixed powder contains a metal powder and an oxide ion conductive solid electrolyte powder.

[0068] The metal is selected from Fe, Ni, and Cu.

[0069] The metal powder may have an average particle diameter in the range of 0.1 μm to 100 μm.

[0070] The oxide ion conductive solid electrolyte is selected from the group consisting of, for example, YSZ (yttrium-doped zirconia), GDC (gadolinium-doped ceria), and mayenite compounds.

[0071] The oxide ion conductive solid electrolyte powder may have an average particle diameter in the range of 0.1 μm to 100 μm.

[0072] In the mixed powder, the metal and the oxide ion conductive solid electrolyte are mixed so that the volume ratio of the metal to the oxide ion conductive solid electrolyte is in the range of 10:90 to 20:80.

[0073] (Step S120) Next, the mixed powder is sintered.

[0074] In the first method, a discharge plasma method is used for sintering.

[0075] The discharge plasma method is a method of sintering a workpiece by combining mechanical pressure and pulsed energization heating. In the discharge plasma method, in addition to thermal energy and mechanical energy, electromagnetic energy by pulsed energization is used, and a sintered body can be obtained by a short-time treatment.

[0076] When the mixed powder prepared in step S110 is heated and sintered using a general method, there arises a problem that metal particles bond to each other during heating, resulting in the generation of coarsened metal particles. When such coarsened metal particles are generated, the dispersibility of the metal particles decreases, and it becomes difficult to obtain a sintered body in which the metal particles are uniformly dispersed.

[0077] On the other hand, in the discharge plasma method, pulsed electromagnetic energy is applied to the mixed powder. The applied energy is applied to the particles of the oxide ion conductive solid electrolyte, which has a higher resistance than the metal particles, and the particles of the oxide ion conductive solid electrolyte are preferentially heated to a high temperature. Therefore, in the obtained sintered body, the bonding between metal particles is suppressed, and the initial dimensions and uniform dispersibility of the metal particles can be maintained even after the sintering treatment.

[0078] For example, in the obtained sintered body, when the cross-section of the sintered body is observed in a region of 500 μm × 500 μm, metal particles having a maximum dimension of less than 100 μm may occupy 80% or more of the total metal particles.

[0079] By the above steps, in the first method, a sintered body having a high conductivity can be manufactured. The conductivity of the sintered body is, for example, 50 S / cm or more at room temperature.

Examples

[0080] Hereinafter, examples of the present invention will be described. In the following description, Examples 1 to 8 are examples, and Examples 11 and 12 are comparative examples.

[0081] (Example 1) A sintered body was manufactured by the following method.

[0082] (Preparation of Mayenite Compound Powder) 4.12 g of calcium carbonate and 2.57 g of α-alumina were weighed respectively. These were put into a pot containing zirconia balls with a diameter of 5 mmφ and 10 cc of isopropanol, and pulverized and mixed for 3 hours by the planetary ball mill method.

[0083] Next, the obtained powder was dried at 100 °C to remove isopropanol. Further, the powder was separated from the zirconia balls by a sieve.

[0084] The obtained powder was put into an alumina crucible and heat-treated at 1200 °C for 5 hours in the air.

[0085] Thereafter, the obtained powder was pulverized for 4 hours by the planetary ball mill method and sieved to produce 12CaO·7Al2O3 mayenite compound powder.

[0086] The average particle size of the mayenite compound powder is 5 μm.

[0087] (Preparation of Mixed Powder) Nickel powder of 200 mesh (equivalent to an average particle size of 100 μm) was prepared.

[0088] 3.77 g of the above-mentioned mayenite compound powder, 1.40 g of nickel powder, and 10 cc of isopropanol were mixed and kneaded with a kneader (Avatore Rettaro; manufactured by Shinchi Co., Ltd.). Thereafter, it was heat-treated at 100 °C to remove isopropanol, and a mixed powder was obtained.

[0089] The volume ratio of nickel powder to mayenite compound powder is 10:90.

[0090] (Sintering Treatment) Next, the obtained mixed powder was subjected to the spark plasma method to produce a sintered body.

[0091] The spark plasma method was carried out using a spark plasma sintering apparatus (Doctor Sinter Lab of Fuji Denpa Kikai Co., Ltd.).

[0092] First, 1.5 g of the mixed powder was placed into a carbon die with a diameter of 1.5 cm, and this was loaded into the apparatus.

[0093] Next, the mixed powder was subjected to a spark plasma treatment under the conditions of a pressure of 50 MPa (uniaxial pressing) and a treatment temperature of 1000 °C. The treatment time was 5 minutes.

[0094] After the treatment, the carbon die was taken out and the sintered body was recovered. As a result, a sintered body with a diameter of 15 mmφ was obtained.

[0095] (Example 2) A sintered body was produced in the same manner as in Example 1.

[0096] However, in this Example 2, the ratio of the nickel powder and the mayenite compound powder contained in the mixed powder was changed from that in the case of Example 1.

[0097] (Example 3) A sintered body was produced in the same manner as in Example 1.

[0098] However, in this Example 3, as the solid electrolyte powder, YSZ powder (average particle size 3 μm) was used instead of the mayenite compound powder.

[0099] (Example 4) A sintered body was produced in the same manner as in Example 3.

[0100] However, in this Example 4, the ratio of the nickel powder and the YSZ powder contained in the mixed powder was changed from that in the case of Example 3.

[0101] (Example 5) A sintered body was produced in the same manner as in Example 1.

[0102] However, in this Example 5, as the solid electrolyte powder, GDC powder (average particle size 3 μm) was used instead of the mayenite compound powder.

[0103] (Example 6) A sintered body was produced in the same manner as in Example 5.

[0104] However, in this Example 6, the ratio of nickel powder and GDC powder contained in the mixed powder was changed from that in Example 5.

[0105] (Example 7) A sintered body was produced in the same manner as in Example 1.

[0106] However, in this Example 7, iron powder was used as the metal powder. The average particle diameter of the iron powder is 150 μm.

[0107] (Example 8) A sintered body was produced in the same manner as in Example 1.

[0108] However, in this Example 8, copper powder was used as the metal powder. The average particle diameter of the copper powder is 50 μm.

[0109] (Example 11) A sintered body was produced in the same manner as in Example 1.

[0110] However, in this Example 11, iron powder was used as the metal powder. The average particle diameter of the iron powder is 150 μm. Also, the ratio of the metal powder and the mayenite compound powder contained in the mixed powder was changed from that in Example 1.

[0111] (Example 12) A sintered body was produced in the same manner as in Example 1.

[0112] However, in this Example 12, copper powder was used as the metal powder. The average particle diameter of the copper powder is 50 μm. Also, the ratio of the metal powder and the mayenite compound powder contained in the mixed powder was changed from that in Example 1.

[0113] The composition etc. of the mixed powder used in each example are collectively shown in Table 1 below.

[0114]

Table 1

[0115] (SEM Observation of Sintered Body) The cross-section of each sintered body was observed by SEM (scanning electron microscope).

[0116] Also, in each sintered body, in an observation region of 500 μm × 500 μm, the ratio of metal particles with a maximum dimension of less than 100 μm to all metal particles was evaluated.

[0117] Fig. 5 shows an example of the cross-sectional morphology of the sintered body obtained in Example 1. In Fig. 5, the light-colored particles correspond to metal particles, and the dark-colored particles correspond to solid electrolyte particles.

[0118] It was found from Fig. 5 that the metal particles have relatively small dimensions and are uniformly dispersed throughout.

[0119] (Measurement of Conductivity) The conductivity of each sintered body was measured by the DC four-terminal method.

[0120] First, samples were prepared from each sintered body by the following method.

[0121] The sintered body was cut out into a rectangular parallelepiped shape having a bottom surface of 1 mm × 1 mm and side surfaces of 1 mm × 7 mm.

[0122] Next, at the end of the obtained rectangular parallelepiped (near one bottom surface), a platinum film (thickness: 200 nm) with a width of 1 mm was formed along a direction perpendicular to the longitudinal direction of the rectangular parallelepiped (i.e., a direction parallel to the bottom surface) so as to surround the side surface of the rectangular parallelepiped.

[0123] The same film formation was also carried out at another three positions on the side surface of the rectangular parallelepiped at a 1 mm pitch. Thereby, four ring-shaped platinum films were arranged at equal intervals from one end to the other end on the side surface of the rectangular parallelepiped.

[0124] Next, using a silver paste, a platinum wire with a diameter of 0.1 mmφ was fixed to each platinum film, dried thoroughly, and a sample was prepared.

[0125] Next, the obtained sample was placed in the sample holder of a measuring device (BioLogic SP-150). Also, the measurement terminals of the measuring device were connected to each platinum wire.

[0126] A current was passed through the sample in a constant current mode via each platinum wire, and the resulting voltage was measured. Thereby, a current-voltage plot excluding the contact resistance of the sample was created. The conductivity of the sample was calculated from the obtained plot.

[0127] In the column of "Evaluation Results" in Table 1 above, the evaluation results obtained for the sintered bodies according to each example are collectively shown.

[0128] From these results, it was found that in the sintered bodies according to Examples 1 to 8, small metal particles with a maximum dimension of 50 μm or less occupy most of the metal particles.

[0129] Also, it was found that the sintered bodies according to Examples 11 to 12 do not have conductivity. On the other hand, it was confirmed that the sintered bodies according to Examples 1 to 8 have high conductivity exceeding 50 S / cm.

[0130] (Aspect of the present invention) The present invention may have the following aspects.

[0131] (Aspect 1) A sintered body for an electrode of an SOFC or SOEC, containing an oxide ion conductive solid electrolyte and a metal, wherein the metal contains at least one of Fe, Ni, and Cu, and the volume ratio of the metal to the oxide ion conductive solid electrolyte is in the range of 10:90 to 20:80. When observing the cross-section of the sintered body in a region of 500 μm × 500 μm, the sintered body in which metal particles with a maximum dimension of less than 100 μm account for 80% or more of the total metal particles.

[0132] (Aspect 2) The sintered body according to Aspect 1, wherein the conductivity at room temperature is 50 S / cm or more.

[0133] (Aspect 3) The sintered body according to Aspect 1 or 2, wherein the content of the metal is less than 50% by weight.

[0134] (Aspect 4) The sintered body according to any one of Aspects 1 to 3, wherein the metal is Ni.

[0135] (Aspect 5) The sintered body according to any one of Aspects 1 to 4, wherein the oxide ion conductive solid electrolyte is selected from the group consisting of YSZ (yttrium-doped zirconia), GDC (gadolinium-doped ceria), and mayenite compounds.

[0136] (Aspect 6) A method for manufacturing a sintered body for an electrode of an SOFC or SOEC, comprising: (1) preparing a mixed powder containing a metal powder and an oxide ion conductive solid electrolyte powder, wherein the metal contains at least one of Fe, Ni, and Cu, the volume ratio of the metal to the oxide ion conductive solid electrolyte is in the range of 10:90 to 20:80, (2) sintering the mixed powder using a spark plasma method to obtain a sintered body.

[0137] (Aspect 7) The method according to Aspect 6, wherein the oxide ion conductive solid electrolyte is selected from the group consisting of YSZ (yttrium-doped zirconia), GDC (gadolinium-doped ceria), and mayenite compounds.

[0138] (Aspect 8) The powder of the metal has an average particle diameter in the range of 0.1 μm to 50 μm, and the method according to embodiment 6 or 7.

[0139] (Embodiment 9) When observing the cross-section of the sintered body in a region of 500 μm × 500 μm, the metal particles having a maximum dimension of less than 100 μm account for 80% or more of the total metal particles, and the method according to any one of embodiments 6 to 8.

Explanation of reference numerals

[0140] 100 SOFC cell 110 Oxygen electrode 120 Fuel electrode 130 Solid electrolyte layer 140 External load 150 Seal structure 160 Housing 170 Seal member 200 SOEC cell 210 Oxygen electrode 220 Fuel electrode 230 Solid electrolyte layer 240 External power source

Claims

1. A sintered body for an electrode of a SOFC or SOEC, containing an oxide ion-conductive solid electrolyte and a metal, wherein the metal contains at least one of Fe, Ni, and Cu, the volume ratio of the metal to the oxide ion-conductive solid electrolyte is in the range of 10:90 to 20:80, and when the cross-section of the sintered body is observed in a region of 500 μm × 500 μm, metal particles having a maximum dimension of less than 100 μm occupy 80% or more of the total metal particles.

2. The sintered body according to claim 1, having a conductivity at room temperature of 50 S / cm or more.

3. The sintered body according to claim 1, wherein the content of the metal is less than 50% by weight.

4. The sintered body according to claim 1, wherein the metal is Ni.

5. The sintered body according to claim 1, wherein the oxide ion-conductive solid electrolyte is selected from the group consisting of YSZ (yttrium-doped zirconia), GDC (gadolinium-doped ceria), and mayenite compounds.

6. A method for manufacturing a sintered body for an electrode of a SOFC or SOEC, (1) preparing a mixed powder containing a metal powder and an oxide ion-conductive solid electrolyte powder, wherein the metal contains at least one of Fe, Ni, and Cu, the volume ratio of the metal to the oxide ion-conductive solid electrolyte is in the range of 10:90 to 20:80, and (2) sintering the mixed powder using a spark plasma method to obtain a sintered body.

7. The method according to claim 6, wherein the oxide ion-conductive solid electrolyte is selected from the group consisting of YSZ (yttrium-doped zirconia), GDC (gadolinium-doped ceria), and mayenite compounds.

8. The method according to claim 6, wherein the powder of the metal has an average particle diameter in the range of 0.1 μm to 50 μm.

9. The method according to claim 6, wherein when the cross section of the sintered body is observed in a region of 500 μm × 500 μm, metal particles having a maximum dimension of less than 100 μm account for 80% or more of the total metal particles.

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