CN1813366A

CN1813366A - Solid oxide fuel cell

Info

Publication number: CN1813366A
Application number: CNA2004800179497A
Authority: CN
Inventors: 芳片邦聪; 三上豪一; 坂元宏年
Original assignee: Dai Nippon Printing Co Ltd
Current assignee: Dai Nippon Printing Co Ltd
Priority date: 2003-06-26
Filing date: 2004-06-25
Publication date: 2006-08-02
Anticipated expiration: 2024-06-25
Also published as: CN100438168C; CN101299466A; CN101299466B

Abstract

A solid oxide fuel cell is disclosed which has improved problems such as vulnerability and high cost conventional planar/tubular solid oxide fuel cells involved. The solid oxide fuel cell is a membrane-free solid oxide fuel cell to which a mixture gas of a fuel gas and an oxidant gas is supplied for generation of electricity, and comprises a substrate (1), an electrolyte (3) which is arranged on one surface of the substrate (1), and at least one electrode body (E) which is composed of a fuel electrode (5) and an air electrode (7) arranged on the same surface of the electrolyte (3) at a certain distance from each other.

Description

Solid oxide fuel cell

Technical Field

The present invention relates to a fuel cell, and more particularly, to a solid oxide fuel cell that stably generates power in a mixed gas of a fuel gas and an oxidant gas.

Background

Conventionally, flat plate type and cylindrical type have been proposed as element designs of solid oxide fuel cells.

A plurality of cells formed in this way are used in a state of being stacked by an interconnector (separator). The interconnector (separator) connects the individual cells in series or in parallel, and performs the function of completely separating the fuel gas and the oxidant gas supplied to the respective cells. Further, a gas seal is provided between each cell and the separator (for example, Japanese patent application laid-open No. 5-3045). However, in such a flat-type battery, since the battery is sealed by applying pressure thereto, the battery is vulnerable to vibration, thermal cycling, and the like, which causes a significant problem in practical use.

On the other hand, cylindrical batteries are those in which a fuel electrode and an air electrode are disposed on the outer peripheral surface and the inner peripheral surface of a cylindrical electrolyte, respectively, and a cylindrical longitudinal onyx type, a cylindrical lateral onyx type, and the like have been proposed (for example, japanese unexamined patent application publication No. h 5-94830). The cylindrical battery has an advantage of excellent gas sealing properties, but has a disadvantage of complicated manufacturing process and high manufacturing cost because the structure is more complicated than that of the flat battery.

In addition, in both the flat cell and the cylindrical cell, the electrolyte is required to be thin in order to improve the performance, and the ohmic resistance of the electrolyte material must be reduced.

Therefore, as an alternative to the above-described flat-plate type and cylindrical type fuel cells, there has been proposed a non-membrane-free type (membrane-free) solid oxide fuel cell in which a fuel electrode and an air electrode are disposed on the same surface of a substrate made of a solid electrolyte and a mixed gas of a fuel gas and an oxidizing gas is supplied to generate electricity (for example, japanese unexamined patent application, first publication No. 8-264195). According to this fuel cell, since it is not necessary to separate the fuel gas and the oxidizing gas, a separator and a gas seal are not necessary, and the structure and the manufacturing process can be greatly simplified.

In such a non-membrane type solid oxide fuel cell, the fuel electrode and the air electrode are formed close to each other on the same surface of the solid electrolyte, and since oxygen ion conduction is thought to occur mainly in the vicinity of the surface layer of the solid electrolyte, the thickness of the electrolyte does not largely affect the performance of the cell as in the case of the flat plate type and the cylindrical type. Therefore, it is possible to increase the thickness of the electrolyte while maintaining the performance of the battery, whereby the vulnerability can be improved.

As described above, in the conventional solid oxide fuel cell, the fragility is improved by increasing the thickness of the electrolyte. However, since most of the components contributing to the battery reaction are located near the surface of the electrolyte, even if the thickness of the electrolyte is increased in this way, the performance as a battery is not greatly improved, and the increase in the thickness of the electrolyte may raise the manufacturing cost.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a solid oxide fuel cell which can improve the vulnerability, reduce the cost, and obtain a high power generation output.

Disclosure of Invention

The first solid oxide fuel cell of the present invention is a cell for solving the above problems, and includes: a substrate; an electrolyte disposed on one surface of the substrate; and at least one electrode body including a fuel electrode and an air electrode disposed on the same surface of the electrolyte at a predetermined interval.

The fuel cell preferably further includes an electrolyte disposed on the other surface of the substrate, and an electrode body including a fuel electrode and an air electrode disposed on the same surface of the electrolyte at a predetermined interval.

The electrode body may be provided in plurality on each surface of the substrate via an electrolyte. In this case, the electrode bodies may be connected by an internal connector disposed on the fuel cell, and the configuration may be such that: an internal connector is provided ina device in which the fuel cell is disposed, and the electrode bodies are connected by the internal connector of the device when the fuel cell is disposed.

In the electrolyte, a groove is preferably formed between adjacent electrode bodies to partition them. Such a groove may be formed so as to penetrate the electrolyte to reach the substrate.

Alternatively, the electrolyte may be partitioned between adjacent electrode bodies. In this case, it is preferable that an insulating material is disposed between the adjacent electrolytes. This makes it possible to easily perform connection by the interconnector and to reliably block the electrolyte.

In the above fuel cell, the electrolyte is preferably formed by printing. Alternatively, the electrolyte may be formed in a plate or sheet shape and mounted on the substrate via an adhesive.

In the fuel cell, the electrode body is preferably configured to: the other electrode surrounds the periphery of the one electrode at a predetermined interval.

The second solid oxide fuel cell of the present invention is a solid oxide fuel cell including a plurality of unit cells each including an electrolyte, a fuel electrode, and an air electrode, and includes a substrate supporting the plurality of unit cells, wherein the electrolyte of each unit cell is disposed on the substrate at a predetermined interval.

A plurality of unit cells may be arranged on each surface of the substrate. In this case, the unit cells may be connected by an internal connector disposed in the fuel cell, and the unit cells may be configured such that: an internal connector is provided in a device on which the fuel cell is disposed, and when the fuel cell is installed, the unit cells are connected by the internal connector of the device.

In sucha fuel cell, the electrolyte is preferably formed by printing. Alternatively, the electrolyte may be formed in a plate shape and mounted on the substrate via an adhesive.

In each of the fuel cells described above, the substrate is preferably made of a ceramic material.

Drawings

Fig. 1 is a partially enlarged sectional view of a first embodiment of a fuel cell of the present invention.

Fig. 2 is a schematic plan view of fig. 1.

Fig. 3 is a view showing an example of the method for manufacturing the fuel cell shown in fig. 1.

Fig. 4 is a partial sectional view (a) and a schematic plan view (b) of a fuel cell according to a second embodiment of the present invention.

Fig. 5 is a diagram showing an example of the method for manufacturing the fuel cell shown in fig. 4.

Fig. 6 is a partial sectional view (a) and a schematic plan view (b) of a fuel cell according to a third embodiment of the present invention.

Fig. 7 is a diagram showing an example of the method for manufacturing the fuel cell shown in fig. 6.

Fig. 8 is a diagram showing another example of the method for manufacturing the fuel cell of the third embodiment.

Fig. 9 is a sectional view showing another example of the fuel cell of the present invention.

Fig. 10 is a plan view showing still another example of the fuel cell of the present invention.

Fig. 11 is a cross-sectional view showing another example of fig. 6.

Fig. 12 is a plan view showing still another example of the fuel cell of the present invention.

Fig. 13 is a partially enlarged sectional view of fig. 12.

Fig. 14 is a sectional view (a) and a schematic plan view (b) showing another example of fig. 6.

Fig. 15 is a plan view (a) and a sectional view (b) of the fuel cell of example 1.

Fig. 16 is a plan view (a) and a sectional view (b) of a fuel cell of example 3.

Fig. 17 is a sectional view of a fuel cell of example 4.

Detailed Description

(first embodiment)

Hereinafter, a first embodiment of the solid oxide fuel cell according to the present invention will be described with reference to the drawings. Fig. 1 is a partially enlarged sectional view of a fuel cell according to the present embodiment, and fig. 2 is a schematic plan view of the fuel cell.

As shown in fig. 1 and 2, this fuel cell includes a sheet-like substrate 1 and an electrolyte 3 laminated on one surface thereof, and a plurality of electrode bodies (unit cells) E each including a pair of a fuel electrode 5 and an air electrode 7 are arranged on the same surface of the electrolyte 3. The fuel electrode 5 and the air electrode 7 of each electrode body E are formed in a band shape and arranged at a predetermined interval. In this case, the distance between the fuel electrode 5 and the air electrode 7 is, for example, preferably 1 to 500 μm, and more preferably 10 to 500 μm.

As described above, a plurality of electrode bodies E are formed on the electrolyte 3, and these electrode bodies are connected in series by the internal connector 9. That is, the air electrode 7 of each electrode body E and the fuel electrode 5 of the electrode body E adjacent thereto are connectedby the interconnector 9.

Next, the material of the fuel cell configured as described above will be described. The substrate 1 is preferably formed using a material having excellent adhesion to the electrolyte 3, and specifically, SUS, or a ceramic material such as an alumina-based material, a silica-based material, or a titanium-based material can be preferably used. In particular, a ceramic material having excellent heat resistance of 1000 ℃ or higher is preferably used. The thickness of the substrate 1 is preferably 50 μm or more.

As the material of the electrolyte 3, a known material of an electrolyte of a solid oxide fuel cell can be used, and for example, oxygen ion conductive ceramic materials such as cerium oxide-based oxides to which samarium, gadolinium and the like are added, lanthanum gallium (ランタン · ガレ — ド) -based oxides to which strontium and magnesium are added, and zirconium oxide-based oxides containing scandium and yttrium can be used. The thickness of the electrolyte 3 is preferably 10 to 5000 μm, and more preferably 50 to 2000 μm.

The fuel electrode 5 and the air electrode 7 may be formed of a ceramic powder material. The average particle diameter of the powder used in this case is preferably 10nm to 100. mu.m, more preferably 50nm to 50 μm, and particularly preferably 100nm to 10 μm. The average particle diameter can be measured, for example, in accordance with JISZ 8901.

The fuel electrode 5 may use, for example, a mixture of a metal catalyst and a ceramic powder material composed of an oxide ionic conductor. As the metal catalyst used in this case, a material having a hydrogen oxidation activity and being stable in a reducing atmosphere, such as nickel, iron, cobalt, and a noble metal (platinum, ruthenium, palladium, etc.), can be used. In addition, as the oxide ion conductor, a material having a fluorite structure or a perovskite structure can be preferably used. Examples of the material having a fluorite structure include cerium oxide containing samarium, gadolinium, or the like, and zirconium oxide containing scandium and yttrium. Examples of the material having a perovskite structure include langasite-based oxides to which strontium and magnesium are added. Among the above materials, the fuel electrode 4 is preferably formed using a mixture of an oxide ion conductor and nickel. The mixing method of the ceramic material made of the oxide ion conductor and nickel may be a physical mixing method, or a method of modifying nickel powder. The above ceramic materials may be used alone in 1 kind or in a mixture of 2 or more kinds. The fuel electrode 5 may be a single metal catalyst.

As the ceramic powder material forming the air electrode 7, for example, a ceramic powder material having perovskiteA metal oxide having a mineral structure or the like and made of Co, Fe, Ni, Cr, Mn or the like. Specifically, there may be mentioned (Sm, Sr) CoO₃、(La、Sr)MnO₃、(La、Sr)CoO₃、(La、Sr)(Fe、Co)O₃、(La、Sr)(Fe、Co、Ni)O₃Etc. oxide, preferably (La, Sr) MnO₃. The above ceramic materials may be used alone in 1 kind or in a mixture of 2 or more kinds.

The fuel electrode 5 and the air electrode 7 are formed by adding an appropriate amount of a binder resin, an organic solvent, or the like to the above-described materials as main components. More specifically, in the mixing of the main component and the binder resin, it is preferable to add the binder resin or the like so that the main component is 50 to 95 wt%. The air electrode 3 and the fuel electrode 5 are formed to have a film thickness of 1 to 500 μm, preferably 10 to 100 μm, after firing.

The electrolyte 3 is also formed by adding an appropriate amount of a binder resin,an organic solvent, or the like to the above-described materials as the main components, as in the case of the fuel electrode 5 and the air electrode 7, but in the mixing of the main components and the binder resin, it is preferable to mix the main components so that the main components are 80% by weight. Alternatively, the powder of the above-mentioned material may be subjected to one-way press molding, followed by CIP molding, and the fired material may be cut into a sheet or flake having a desired thickness and size at a predetermined temperature and time. Then, the plate-like or sheet-like electrolyte 3 is bonded to the substrate 1 with an adhesive, whereby a fuel cell can be formed. In the case of forming the electrolyte 3 by printing, it is preferable that a stress relaxation layer made of an adhesive material having an intermediate value of thermal expansion coefficients between the substrate 1 and the electrolyte 3 is present between them. This prevents the occurrence of cracks in the electrolyte of the thin film during firing due to the difference in the coefficients of expansion between the two.

The fuel cell configured as described above generates power as follows. First, a mixed gas of a fuel gas composed of methane and a hydrocarbon such as ethane and an oxidant gas such as air is supplied onto one surface of the substrate 1 on which the electrode body C is formed in a high temperature state (for example, 400 to 1000 ℃). This causes ion conduction mainly in the vicinity of the surface layer of the electrolyte 3 between the fuel electrode 5 and the air electrode 7, thereby generating power.

In the fuel cell having the above-described structure, since the portion other than the vicinity of the surface layer of the electrolyte 3 does not contribute much to the cell reaction, the manufacturing cost can be reduced by making the electrolyte 3 thin to a certain thickness without impairing the cell performance. Therefore, in the fuel cellof the present embodiment, since the electrolyte 3 is supported on the substrate 1, even if the electrolyte 3 is made thin, high durability against vibration or thermal cycling can be maintained.

In addition, a high voltage can be obtained by connecting the plurality of electrode bodies E in series via the interconnector 9 as described above. The interconnector 9 may be made of a conductive metal or metal material such as Pt, Au, Ag, Ni, Cu, SUS, or La (Cr, Mg) O₃、(La、Ca)CrO₃、(La、Sr)CrO₃The lanthanum chromite and other conductive ceramic materials can be used alone, or more than 2 kinds of these materials can be mixed. In addition, additives such as the above-mentioned binder resin may be added to these materials.

In addition, the interconnector 9 may be formed on the electrolyte 3 via an insulating layer. In this case, the insulating layer is preferably made of a ceramic material in view of heat resistance. Examples of the ceramic material used here include an alumina-based material, a silica-based material, and a titania-based material. When the interconnector 9 is disposed on the electrolyte 3 via the insulating layer in this way, electrical contact between the interconnector 9 and the electrolyte 3 can be prevented. Therefore, there are the following advantages. When an interconnector is formed on an electrolyte to connect adjacent electrode bodies as in the prior art, the interconnector may exhibit conductivity and ion conductivity equivalent to that of the electrode reaction, and therefore, may act similarly to the electrode to reduce the original electromotive force. In contrast, when the above configuration is adopted, the interconnector 9 and the electrolyte 3 are not in electrical contact with each other, and therefore, a decrease in electromotive force can be prevented. Further, the instability of the electromotive force can be prevented, and desired output characteristicscan be obtained.

Next, an example of the method for manufacturing the fuel cell will be described with reference to fig. 3. First, the above-mentioned powdery materials for the electrolyte 3, the fuel electrode 5, and the air electrode 7 are used as main components, and an appropriate amount of a binder resin, an organic solvent, and the like are added thereto and mixed to prepare an electrolyte paste, a fuel electrode paste, and an air electrode paste, respectively. The viscosity of each paste is preferably 10³～10⁶mPa · s to the right to suit screen printing to be described below. Similarly, the internal connector paste is also prepared by adding a binder resin to the above powder material. The viscosity of the paste was the same as described above.

Next, the electrolyte paste is applied to the substrate by screen printing, and then dried and fired at a predetermined time and temperature, thereby forming the electrolyte 3 (fig. 3 (a)). Next, the fuel electrode paste is applied in a band shape at a plurality of positions on the electrolyte by a screen printing method, and then dried and fired at a predetermined time and temperature to form a plurality of fuel electrodes 5 (fig. 3 (b)). Next, an air electrode paste is applied to the positions facing the fuel electrodes 5 by screen printing, and dried and fired at a predetermined time and temperature, thereby forming a plurality of electrode bodies C (fig. 3 (C)). Finally, the interconnector paste is applied in a linear shape between the electrode bodies C by a screen printing method so that the plurality of electrode bodies C are connected in series, thereby forming the interconnector 9 (fig. 3 (d)).

In the fuel cell, since the electrolyte is present between the adjacent electrode bodies, the electrolyte can serve as a moving path of oxygen ions during power generation. Therefore, the electrolyte between the electrode bodies and the fuel electrode and the air electrode sandwiching the electrolyte may constitute a fuel cell to generate electricity. It is considered that the electromotive force of the original unit cells and the electromotive force of the cell formed between the unit cells cancel each other out to cause an internal short-circuited state, and thus the total electromotive force of the fuel cell decreases. Therefore, even if the number of electrode bodies is increased, the electromotive force as a whole may not be "electromotive force generated by one electrode body × the number of electrode bodies". A second embodiment of the present invention in consideration of this point will be described below.

(second embodiment)

Next, a second embodiment of the solid oxide fuel cell of the present invention will be explained. Fig. 4 is a side view (a) and a plan view (b) of the fuel cell of the present embodiment. Here, a fuel cell having 2 electrode bodies will be explained.

As shown in fig. 4, this fuel cell includes a sheet-like substrate 1 and an electrolyte 3 formed on one surface thereof, and 2 electrode bodies E each including a pair of a fuel electrode 5 and an air electrode 7 are arranged on the same surface of the electrolyte 3. The structure of each electrode body E is the same as that of the first embodiment. Further, between the electrode bodies E, grooves V are formed to partition them. In addition, an electrode body E₁And another electrode body E adjacent thereto₂The fuel electrode 5 of (a) is connected across these grooves by an internal connector 9. A part of the inner coupler 9 is in a state of entering the groove V.

The materials forming the substrate 1, the electrolyte 3, the fuel electrode 5, the air electrode 7, and the interconnector 9 of this embodiment are the same as those described in the first embodiment, and therefore, detaileddescription thereof is omitted. The power generation method is also the same as that of the first embodiment.

As described above, according to the present embodiment, the two electrode bodies E₁、E₂The grooves V having a groove depth D larger than the thickness R of the remaining electrolyte 3 (e.g., D800 μm or R200 μm) are formed in the electrolyte 3 between the two electrode bodies E, so that the number of the electrode bodies E can be reduced₁、E₂The oxygen ions in the electrolyte 3 therebetween. As a result, power generation is suppressed as much as possible, and a drop in voltage can be prevented. The width of the groove V is preferably 1 to 5000 μm, as in the third embodiment described later.

Next, a method for manufacturing the fuel cell will be described with reference to fig. 5. Here, the electrolyte paste, the fuel electrode paste, the air electrode paste, and the interconnector paste used are the same as those described in the first embodiment. First, as shown in fig. 5(a) to 5(c), the electrolyte 3, the fuel electrode 5, and the air electrode 7 are formed on the substrate 1. The formation method up to this point is the same as that of the first embodiment.

Next, two electrode bodies E on the electrolyte substrate 3₁、E₂A groove V is formed therebetween (FIG. 5 (d)). In this case, the groove V may be formed by, for example, shot peening, laser processing, cutting processing, or the like. Finally, as shown in fig. 5(E), one electrode body E is provided₁And the other electrode body E₂The internal connector 1 is formed by applying the internal connector paste between the air electrodes 7, and then the fuel cell shown in fig. 4 is completed.

In this embodiment, the grooves are formed in the electrolyte between the electrode bodies, whereby the movement path of oxygen ions can be reduced and power generation between the electrode bodies can be suppressed. This will be explained below.

(third embodiment)

A third embodiment of the solid oxide fuel cell according to the present invention will be described below with reference to the drawings. Fig. 6 is a partial sectional view (a) and a schematic plan view (b) of the fuel cell of the present embodiment.

As shown in fig. 6, the fuel cell includes a sheet-like substrate 1 and a plurality of unit cells C (here, two C are shown) arranged on one surface thereof₁、C₂) The battery cells C are connected in series by the internal connector 9.

Each unit cell C has a rectangular electrolyte 3 disposed on one surface of the substrate 1, and a pair of fuel electrodes 5 and air electrodes 7 disposed on the same surface of the electrolyte 3. The electrolyte 3 of each unit cell C is disposed so as to form a gap S with a predetermined interval from the electrolyte 3 of the adjacent unit cell C. The interval is preferably 10 to 5000 μm, and more preferably 10 to 500 μm. The fuel electrode 5 and the air electrode 7 on each electrolyte 3 are formed in a band shape and arranged at a predetermined interval. In this case, the interval L between the fuel electrode 5 and the air electrode 7 is preferably set, for exampleIs 1 to 5000 μm, and more preferably 10 to 500 μm. In addition, as shown in fig. 2, in this fuel cell, electrodes disposed at both ends, that is, one unit cell C₁Fuel electrode 5 and another unit cell C₂The air electrodes 7 are each formed with a current collecting portion 8 for extracting current.

The interconnector 9 connects the adjacent unit cells C as described above, specifically, connects one unit cell C₁Air electrode 7 and another unit cell C₂And the fuel electrode 5. At this time, the interconnector 9 is formed on the electrolyte 5 so as to cross the gap S in the substrate 1 between the adjacent unit cells C.

The materials forming the substrate 1, the electrolyte 3, the fuel electrode 5, the air electrode 7, and the interconnector 9 of this embodiment are the same as those described in the first embodiment, and therefore, detailed description thereof is omitted. The power generation method is also the same as that of the first embodiment. The material of the current collecting portion 8 is the same as that of the interconnector.

As described above, in the fuel cell of the present embodiment, since the electrolyte 3 is supported by the substrate 1, high durability against vibration and thermal cycles can be maintained even if the electrolyte 3 is made thin, as in the above embodiments. In the fuel cell, the unit cells C are arranged to be separated by a gap and connected by the interconnector 9. Therefore, since the electrolyte 3 is not present between the unit cells C, oxygen ions can be prevented from moving between the unit cells C, and the formation of a fuel cell between the unit cells can be prevented. As a result, a decrease in the electromotive force of the fuel cell can be prevented, and a high power generation output can be obtained.

Next, an example of the method for manufacturing the fuel cell will be described with reference to fig. 7. First, the powdery materials for the electrolyte 3, the fuel electrode 5, and the air electrode 7 are used as main components, and an appropriate amount of a binder resin, an organic solvent, and the like are added thereto and kneaded to prepare an electrolyte paste, a fuel electrode paste, and an air electrode paste, respectively. The viscosity of each paste is preferably 10³～10⁶mPas to the right or left, so as to be suitable for a screen printing method to be described below. Similarly, theinternal connector paste is also prepared by adding an additive such as a binder resin to the powder material. The viscosity of the paste was the same as described above.

Next, an electrolyte paste is applied to a plurality of positions on the substrate 1 by a screen printing method, and then dried at a predetermined time and temperature, thereby forming a plurality of rectangular electrolytes 3 arranged at predetermined intervals S (fig. 7 (a)). Next, the fuel electrode paste 7 is applied in a band shape on each electrolyte 3 by screen printing, and then dried and fired at a predetermined time and temperature to form the fuel electrode 5 (fig. 7 (b)). Next, an air electrode paste is applied by screen printing to a position facing the fuel electrode 5 on each electrolyte 3, and dried and sintered at a predetermined time and temperature to form the air electrode 7. Thus, a plurality of unit cells C are formed (fig. 7C). Finally, the interconnector 9 is formed by linearly applying an interconnector paste between the unit cells C by a screen printing method so that the unit cells C are connected in series. At this time, the interconnectors 9 are formed so as to cross the gap S between the electrolytes 3 and pass through the substrate 1. Further, a current collecting portion 8 is formed at an end portion of the inner connector 9. Through the above steps, the fuel cell is completed (fig. 7 (d)). When a plurality of unit cells are formed using a photosensitive polymer as a binder resin, a plurality of unit cells and an electrolyte having an arbitrary pattern shape can be obtained by applying and drying a paste, exposing the paste to light in a plurality of pattern shapes using a mask, and then sintering the paste after a step of removing unexposed portions.

While the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the scope of the invention. For example, although the respective pastes are applied by the screen printing method in the manufacturing method described in each of the above embodiments, the method is not limited thereto, and printing methods such as a spread coating method, a spray coating method, a lithography method, an electrophoretic coating method, a roll coating method, a dispensing coat (discrete coat) method, CVD, EVD, a sputtering method, and a transfer method, and other general printing methods may be used. As a post-process after printing, hydrostatic pressing, hydraulic pressing, and other general pressing processes may be used.

In the case of forming the electrolyte by the above-described printing method or the like, it is preferable that a stress relaxation layer made of an adhesive material having an intermediate value of thermal expansion coefficients between the substrate 1 and the electrolyte 3 is present between them. This prevents the electrolyte from cracking during sintering due to the difference in the expansion coefficients of the two.

In addition, a fuel cell may be constructed by preparing a plate-like or sheet-like electrolyte and attaching the electrolyte to a substrate with an adhesive or the like. In this case, particularly when forming the fuel cell of the third embodiment, a plurality of electrolytes of a predetermined size may be attached to the substrate for each unit cell to form the fuel cell. Alternatively, after the electrolyte is applied, the electrolyte may be cut by cutting, and each unit cell may be separated. For example, as shown in fig. 8, after the electrolyte 3 is pasted to form both electrodes 5 and 7 (fig. 8(a)), the electrolyte 3 is separated by forming a groove V penetrating the electrolyte 3 to the substrate 1 by cutting, and a plurality of unit cells C can be formed (fig. 8 (b)).

In each of the above embodiments, the electrolyte 3, the fuel electrode 5, and the air electrode 7 are formed only on one surface of the substrate 1, but the electrolyte 3, the fuel electrode 5, and the air electrode 7 may be formed on the other surface of the substrate 1 as shown in fig. 9. Fig. 9(a) to 9(c) correspond to the first to third embodiments. As a manufacturing method in this case, for example, in each step of forming the electrolyte 3, the fuel electrode 5, and the air electrode 7 on one surface of the substrate 1, the electrolyte, the fuel electrode, and the air electrode are similarly formed on the other surface of the substrate 1, and the cells of the same type are formed on both surfaces of the substrate 1. By doing so, it is possible to make the fuel cell dense and obtain high power generation output.

In the above description, the plurality of electrode bodies E or the unit cells C are connected in series by the interconnector 9, but may be connected in parallel. For example, in the first embodiment, as shown in fig. 10(a), the fuel electrodes 5 and the air electrodes 7 of 2 electrode bodies E may be connected to each other by interconnectors 9. Alternatively, as shown in fig. 10(b), the series connection and the parallel connection may be made simultaneously. By such a combination, a desired voltage and current can be obtained. It is needless to say that the fuel cell may be configured by one electrode body E without using a plurality of electrode bodies E.

In addition, a gap may be formed between adjacent electrolytes 3, and as shown in fig. 11, an insulating film 10 may be disposed in the gap S between the electrolytes 3. Thereby, the adjacent electrolytes 3 are separated by the insulating film 10, the electrical separation between the unit cells C becomes more reliable, and the connection by the interconnector 9 becomes easier. Therefore, the fuel cell can be more reliably prevented from being formed between the unit cells C, so that high power generation output can be obtained.

In this case, the insulating film 10 is preferably formed of a ceramic material, and for example, an alumina-based or silica-based ceramic material can be used. The particle size of the ceramic material powder constituting the insulating film 10 is generally 10nm to 100 μm, preferably 100mn to 10 μm, as in the case of the electrolyte and the like. The insulating film 10 is mainly composed of the above-mentioned ceramic material powder, and an appropriate amount of a binder resin, an organic solvent, or the like may be added. The sintered film thickness is 1 to 500 μm, preferably 10 to 100 μm, as in the case of the electrolyte.

In the above embodiments, the electrodes are formed in a band shape and arranged so that the fuel electrode and the air electrode are alternately arranged, but the shape of each electrode is not limited to the band shape as described above, and may be configured as follows. As shown in fig. 12 and 13, the fuel cell includes 24 electrode bodies E, and these electrode bodies E are connected by an interconnector 9.

Each electrode body E is composed of a fuel electrode 5 and an air electrode 7, and the rectangular air electrode 7 is surrounded by the frame-shaped fuel electrode 5 at a predetermined interval. The fuel electrode 5 has a rectangular shape in accordance with the air electrode 7. In this case, the distance between the fuel electrode 5 and the air electrode 7 is, for example, preferably 1 to 1000 μm, and more preferably 10 to 500 μm. Further, the fuel electrode 5 and the air electrode 7 are respectively provided with current collecting

portions

51 and 71 for extracting current. The current collecting portion 51 of the fuel electrode 5 and the current collecting portion 71 of the air electrode 7 of the electrode body E adjacent thereto are connected by the interconnector 9, and the electrode bodies E are connected in series. The spacing between adjacent electrode bodies E is, for example, preferably 10 to 5000 μm, and more preferably 1000 to 3000 μm.

The inner connector 9 is formed as shown in fig. 13. As shown in the figure, in the interval (crossing interval) between the

current collecting portions

51 and 71 at both ends of each interconnector, the insulating layer 11 is formed on the fuel electrode 5, the air electrode 7, and the electrolyte 1, and the interconnector 9 is formed on the insulating layer 11. Thereby, the interconnector 9 passes over the fuel electrode 5 and is not short-circuited therewith.

With the above configuration, the integration can be facilitated, and as a result, a high power generation output can be obtained. The shape of the fuel electrode and the air electrode may be, for example, circular or polygonal, instead of the rectangular shape described above.

In the third embodiment, the electrolyte 3 is formed on the upper surface of the substrate 1, but may be formed as follows. That is, as shown in fig. 14, in this fuel cell, 2 recesses 11 having a rectangular shape in plan view are formed on one surface of the substrate 1, and the electrolyte 3 of each unit cell C is filled in each recess 11. Thereby, each electrolyte 3 is in a state of being blocked by the walls 14 between the concave portions 13. In this case, the depth of each recess 13 is preferably 5 μm to 5 mm. This is because: when the thickness is less than 5 μm, it is difficult to dispose the electrolyte 3 so as not to protrude from the inside of the concave portion 13; if the thickness is more than 5mm, the electrolyte 3 has a large number of portions that do not contribute to the battery reaction, resulting in high cost.

In this fuel cell, since the electrolyte 3 of each unit cell C is disposed in each recess 13 formed in the substrate 1, each electrolyte 3 is separated by the wall 11 formed between the recesses 13. Therefore, the electrolyte 3 is in a non-contact state between the adjacent unit cells C, and therefore, the possibility that the electrolyte existing between the adjacent electrodes becomes a path of oxygen ions as in the conventional example and the electromotive force can be reduced. As a result, high output can be obtained.

The interconnector in the above-described embodiment is described in the drawings as being in contact with the side surfaces of the electrodes, but an end portion of the interconnector may be connected to the upper surface of each electrode.

The present invention will be described in more detail below with reference to examples.

(example 1)

Example 1 a solid oxide fuel cell shown in fig. 15 was produced. Fig. 15(a) is a plan view of the fuel cell of example 1, and fig. 15(b) is a sectional view thereof. Using GDC (Ce)_0.9Gd_0.1O_1.9) The powder (0.05 to 5 μm, average particle diameter 0.5 μm) is used as an electrolyte material, and a small amount of cellulose binder resin is mixed therewith to prepare an electrolyte paste with a weight ratio of 95: 5. The viscosity of the electrolyte paste was adjusted to 5X 10 suitable for screen printing by dilution with a solvent⁵mPas is about.

NiO powder (0.01-10 μm, average particle diameter 1 μm), SDC (Ce)_0.8Sm_0.2O_1.9) The powders (particle diameter 0.01-10 μm, average particle diameter 0.1 μm) were mixed at a weight ratio of 7: 3 to prepare a fuel electrode material, and a cellulose binder resin was added to prepare a fuel electrode paste having a mixture ratio of 80 wt%. That is, the mixture and the binder resin were mixed so that the weight ratio of the mixture to the binder resin was 80: 20. The viscosity of the paste is adjusted to 5X 10 suitable for screen printing by dilution with asolvent⁵mPas is about.

Next, SSC (Sm) is used_0.5Sr_0.5CoO₃) Powder (0.01 to 10 μm, average particle diameter 1 μm) as an air electrode material, and a cellulose binder resin were added to prepare an air electrode paste such that the proportion of the powder was 80%. That is, the weight ratio of SSC powder to binder resin is 80: 20. Diluting with solvent to make the viscosity of air electrode paste 5 × 10 suitable for screen printing like fuel electrode⁵mPas is about. In addition, an alumina-based substrate having a thickness of 1mm and 10mm square was used as a substrateA substrate 1.

Next, the above electrolyte paste was applied to the substrate 1 by screen printing to a size of 10mm square, dried at 130 ℃ for 15 minutes, and then sintered at 1500 ℃ for 10 hours to form the electrolyte 3 having a thickness of 200 μm after sintering. Then, the paste was applied to a width of 500 μm and a length of 7mm by screen printing. Subsequently, the fuel electrode 5 was dried at 130 ℃ for 15 minutes and then sintered at 1450 ℃ for 1 hour to form a sintered fuel electrode having a thickness of 30 μm. Next, an air electrode paste was applied to the same surface of the electrolyte 3 by a screen printing method. At this time, the air electrode paste was applied to a width of 500 μm, a length of 7mm, and a distance of 500 μm from the fuel electrode. Then, the resulting material was dried at 130 ℃ for 15 minutes and then sintered at 1200 ℃ for 1 hour in the same manner as the fuel electrode, to form an air electrode 7 having a thickness of 30 μm after sintering. Through the above steps, a solid oxide fuel cell having 1 electrode body was produced.

The following evaluation experiment was performed for example 1 thus produced. That is, a mixed gas of methane and oxygen is introduced at 800 ℃ to cause a reaction The nickel oxide as the fuel electrode 5 was subjected to reduction treatment, and the current-voltage characteristics were evaluated. In addition, hydrogen gas may be introduced in place of the mixed gas for the reduction treatment.

As a result, in example 1, 65mW/cm was obtained²The maximum output density of (a) was confirmed to be a solid oxide fuel cell.

(example 2)

Next, example 2 will be explained. The difference from example 1 is that a stress relaxation layer is present between the electrolyte and the substrate. In this example 2, GDC and Al were mixed₂O₃The powders (0.1 to 10 μm, average particle diameter 3 μm) are mixed at a weight ratio of 50: 50 to prepare a stress relaxation layer paste. The paste for the stress relaxation layer is diluted with a solvent so that the viscosity of the paste becomes 5X 10 suitable for screen printing⁵mPas is about.

Other materials are the same as those in example 1, and therefore, detailed description thereof is omitted.

As a manufacturing method, first, a stress relaxation layer paste was applied to the substrate 1 to a coating thickness of 30 μm, and then dried at 130 ℃ for 15 minutes. Then, the electrolyte, the fuel electrode, and the air electrode were formed in this order, as in example 1.

The fuel cell formed as described above can prevent the occurrence of cracks in the electrolyte of the thin film as compared with a fuel cell without a stress relaxation layer. In addition, in terms of battery performance, 65mW/cm was obtained in the same manner as in example 1²The maximum output density of (a).

(example 3)

Example 3a solid oxide fuel cellshown in fig. 16 was produced. The materials forming the substrate, electrolyte, and electrodes were the same as in example 1. An Au powder (0.1 to 5 μm, average particle diameter 2.5 μm) was used as a material for connecting an interconnector and a collector between unit cells, and a cellulose-based binder resin was mixed therewith to prepare a paste for an interconnector and a collector. The paste for internal connector was made to have a viscosity of 5X 10 suitable for screen printing⁵mPa·s。

Next, the above-described electrolyte paste is applied on the substrate 1 by a screen printing method to form a plurality of rectangular electrolytes. At this time, the electrolyte paste was patterned so that two electrolytes having a size of 9 × 4.2mm square spaced apart by 0.6mm and a distance from the edge of the substrate was 0.5 mm. Then, after drying at 130 ℃ for 15 minutes, the electrolyte 3 was sintered at 1500 ℃ for 10 hours to form a sintered electrolyte having a thickness of 200 μm. Next, a fuel electrode paste is applied to each electrolyte 3 by a screen printing method. At this time, the fuel electrode paste was applied so that the fuel electrodes 5 having a width of 500 μm, a length of 7mm and an application thickness of 50 μm were formed on the respective electrolytes 3. Then, the plate was dried at 130 ℃ for 15 minutes and then sintered at 1450 ℃ for 1 hour to a thickness of 30 μm after sintering. Next, an air electrode paste is applied to the same surface of each of the electrolytes 3 by a screen printing method. At this time, the air electrode paste was applied so that air electrodes 7 having a width of 500 μm, a length of 7mm, a coating thickness of 50 μm, and a distance of 500 μm from the fuel electrode 5 were formed on the respective electrolytes 3. Then, similarly to the fuel electrode 5, the resultant was dried at 130 ℃ for 15 minutes and then sintered at 1200 ℃ for 1 hour. The thickness after sintering was adjusted to 30 μm.

Next, an internal connector paste (2 μm wide and 50 μm thick) was applied by screen printing, and the unit cells C were connected in series as shown in fig. 16, thereby forming current collecting portions 8 on the electrodes at both ends of the battery. Thus, the solid oxide fuel cell of example 3 was manufactured.

Comparative example 1, which is a comparison with example 3, was prepared in the following manner. That is, in comparative example 1, an electrolyte having a size of 10X 10mm and a thickness of 1mm was prepared and used as a substrate. Then, on the electrolyte, 2 fuel electrodes and air electrodes were each formed with the same size and interval as in example 3, and connected in series by an interconnector. In addition, comparative example 2 having 1 unit cell was also prepared.

The following evaluation experiments were performed for example 3 and comparative example 1 thus produced. That is, a mixed gas of methane and oxygen is introduced at 800 ℃ to cause a reaction The nickel oxide as the fuel electrode 5 was subjected to reduction treatment, and the current-voltage characteristics were evaluated. In addition, hydrogen gas may be introduced in place of the mixed gas for the reduction treatment.

As a result, the electromotive force of comparative example 2 having 1 unit cell was 610mV, and the electromotive force of example 3 having 2 unit cells was 1190 mV. On the other hand, in comparative example 1 having 2 sets of electrodes, an electromotive force of 900mV was obtained. From the above results, it is understood that comparative example 1 does not reach 2 times of the electromotive force obtained in comparative example 2 due to the internal short circuit phenomenon. On the contrary, in example 3, it is found that the electrolyte is disposed at a predetermined interval, so that the internal short-circuit phenomenon is reduced and the electromotive force about 2 times as large as that of comparative example 2 can be obtained.

(example 4)

In example 4, an insulating film was disposed between each unit cell of the fuel cell shown in fig. 16. As a result, as shown in fig. 17, the adjacent electrolytes 3 are separated by the insulating film 10, and the electrical separation between the unit cells C becomes more reliable, and the connection of the interconnector 9 can be made easy and reliable. Therefore, the fuel cell can be more reliably prevented from being formed between the unit cells C, and high power generation output can be obtained.

In this case, the insulating film 10 is preferably formed using a ceramic material, and for example, an alumina-based or silica-based ceramic material may be used. The particle size of the ceramic material powder constituting the insulating film 10 is generally 10nm to 100 μm, preferably 100nm to 10 μm, as in the case of the electrolyte and the like. The insulating film 10 is mainly composed of the above-described ceramic material powder, and an appropriate amount of a binder resin, an organic solvent, or the like may be added. The film thickness after firing is 1 to 500 μm, preferably 10 to 100 μm, in the same manner as the electrolyte and the like.

The same materials as in example 3 were prepared for the electrolyte paste, the fuel electrode paste, the air electrode paste, and the substrate. Au powder (0.1 to 5 μm, average particle diameter 2.5 μm) is used as a material for an interconnector and a collector for connecting unit cells, and a cellulose-based binder resin is mixed with the Au powder to prepare an interconnector paste. The paste for the interconnector was made to have a viscosity of 5X 10 suitable for the screen printing method⁵mPa · s. In addition, aninsulating film paste for forming an insulating film is prepared. This is obtained by mixing a cellulose-based binder resin with alumina powder (particle size of 0.1 to 10 μm).

Next, an insulating film paste is applied to a predetermined position between the two electrolytes 3 on the substrate 1, and the paste is sintered at 1800 ℃. Next, the electrolyte 3, the fuel electrode 5, and the air electrode 7 were formed in the same manner as in example 3. At this time, the electrolyte 3 is positioned so as to sandwich the insulating film paste. Finally, as in example 3, two unit cells C were connected in series by the internal connector 9, and the current collecting portions 8 were formed on the electrodes at both ends of the battery. Thus, the solid oxide fuel cell of example 4 was manufactured.

The same experiment as in example 4 was conducted for this example 4, and as a result, the same performance as in example was exhibited.

Industrial applicability

According to the present invention, a solid oxide fuel cell can be provided which can improve the vulnerability, can reduce the cost, and can obtain a high power generation output.

Claims

1. A solid oxide fuel cell comprising:

a substrate;

an electrolyte disposed on one surface of the substrate; and

and at least one electrode body including a fuel electrode and an air electrode disposed on the same surface of the electrolyte at a predetermined interval.

2. The solid oxide fuel cell according to claim 1, further comprising:

an electrolyte disposed on the other surface of the substrate; and

and an electrode body including a fuel electrode and an air electrode disposed on the same surface of the electrolyte at a predetermined interval.

3. The solid oxide fuel cell according to claim 1 or 2, wherein:

a plurality of the electrode bodies are arranged.

4. The solid oxide fuel cell according to claim 3, wherein:

the electrode assembly further includes an internal connector for connecting the plurality of electrode bodies.

5. The solid oxide fuel cell according to claim 3 or 4, wherein:

on the electrolyte, between adjacent electrode bodies, a groove that separates the electrode bodies is formed.

6. The solid oxide fuel cell according to claim 3 or 4, characterized in that;

the electrolyte is partitioned between the adjacent electrode bodies.

7. The solid oxide fuel cell according to claim 6, wherein:

an insulating material is disposed between adjacent ones of the electrolytes.

8. The solid oxide fuel cell according to any one of claims 1 to 7, wherein:

the electrolyte is formed by printing.

9. The solid oxide fuel cell according to any one of claims 1 to 7, wherein:

the electrolyte is formed in a plate shape, and the electrolyte is mounted on the substrate by an adhesive.

10. The solid oxide fuel cell according to claim 5, wherein:

the trough extends through the electrolyte to the substrate.

11. The solid oxide fuel cell according to any one of claims 1 to 10, wherein:

the electrode body is configured to: the other electrode surrounds the periphery of the one electrode at a predetermined interval.

12. A solid oxide fuel cell comprising a plurality of unit cells each having an electrolyte, a fuel electrode, and an air electrode, wherein:

a substrate supporting the plurality of unit cells;

the electrolyte of each unit cell is disposed on the substrate at a predetermined interval.

13. The solid oxide fuel cell as claimed in claim 12, wherein:

and an internal connector for connecting the plurality of battery cells.

14. The solid oxide fuel cell according to claim 12 or 13, wherein:

the electrolyte is formed by printing.

15. The solid oxide fuel cell according to claim 12 or 13, wherein:

16. The solid oxide fuel cell according to any one of claims 1 to 15, wherein:

the substrate is composed of a ceramic material.