JP5124968B2 - Solid oxide fuel cell and manufacturing method thereof - Google Patents

Description

  The present invention relates to a solid oxide fuel cell that generates electric power by supplying a fuel gas and an oxidant gas, and a method for manufacturing the same.

  Conventionally, a flat plate type, a cylindrical type, and the like have been proposed as cell designs for solid oxide fuel cells. However, there are problems with the current cell design. In order to improve the performance of both flat and cylindrical cells, it is necessary to reduce the internal resistance by thinning the electrolyte. However, if the electrolyte is too thin, it becomes vulnerable to vibration and thermal cycles. This is a problem that vibration resistance and durability are lowered.

In order to solve the above problems, for example, as shown in Patent Documents 1 and 2, recently, there is a cell structure in which an electrolyte and a counter electrode are supported by an electrode or a current collector.
JP 2005-327511 A JP 2004-303508 A

  However, in the structures described in Patent Documents 1 and 2, since the cell is supported from one side, when heat is applied as in firing or power generation during manufacturing, the difference in coefficient of thermal expansion between the cell and the support substrate. Due to this, the cell may be warped. And there existed a problem that such a curvature led to damage of a cell.

  The present invention has been made to solve the above problems, and in a fuel cell having a structure in which a cell is supported by a support substrate, the cell is prevented from warping when heat is applied during production or power generation. It is an object of the present invention to provide a solid oxide fuel cell capable of preventing damage.

A solid oxide fuel cell according to the present invention has been made to solve the above-described problems, and includes a thin film electrolyte, a thin film fuel electrode disposed on one surface of the electrolyte, and the electrolyte. A thin film-like air electrode disposed on the other surface, a pair of support substrates disposed on the surfaces of the fuel electrode and the air electrode opposite to the electrolyte, and the fuel electrode or air electrode of each support substrate A pair of separators disposed on the opposite side of the support substrate, the support substrate is porous and conductive, and is bonded to the fuel electrode or the air electrode by firing.

  According to this structure, it has the structure which pinched | interposed the cell which consists of electrolyte, a fuel electrode, and an air electrode with a pair of support substrate which consists of the same material. Therefore, even if there is a difference in the coefficient of thermal expansion between the cell and the support substrate, since the cell is sandwiched between the support substrates having the same coefficient of thermal expansion, for example, when heat is applied as in manufacturing In addition, the cell can be prevented from warping. As a result, cell damage can be prevented.

  Further, as described above, since the cell is sandwiched between the pair of support substrates, the support substrate also serves to protect the cells. Therefore, this also prevents cell damage.

In the above fuel cell, the support substrate, by firing, by being joined to the fuel electrode or air electrode, the adhesion between the electrode and the supporting substrate is increased to improve the current collecting performance of the supporting substrate, and the electrode The contact resistance between the support substrates can be lowered.

  The electrolyte, fuel electrode, and air electrode are formed in a thin film shape, and the thickness is preferably 1 to 100 μm.

A first manufacturing method of a solid oxide fuel cell according to the present invention is made in order to solve the above-described problem, and a thin film is formed on one surface of a porous and conductive first support substrate. Forming a thin fuel electrode, forming a thin air electrode on one surface of a porous and conductive second support substrate , and forming a thin film electrolyte on the fuel electrode or air electrode A step of bonding the first and second support substrates so that the electrolyte and the fuel electrode or the air electrode face each other, and firing while pressing , and the first and second Providing a separator on the other surface of the support substrate .

  In the manufacturing method, the electrolyte, the fuel electrode, and the air electrode can be formed by printing, for example. Alternatively, an electrolyte or the like can be formed by preparing and transferring a so-called green body made of a mixture of a powder material and a binder for forming these on a transfer sheet. In addition, an electrolyte or the like can be formed by a tape formed by a tape casting method, a vacuum method such as sputtering, a solution method such as electrodeposition, an electrostatic spraying method, or the like.

Further, a second method for producing a solid oxide fuel cell according to the present invention includes a step of forming a thin film-like fuel electrode on one surface of a porous and conductive first support substrate, Forming a thin film-like air electrode on one surface of the second support substrate having high quality and conductivity, and applying an electrolyte material paste for forming an electrolyte to the fuel electrode and the air electrode, respectively And bonding the first and second support substrates so that the electrolyte material paste faces each other, firing them while applying pressure , and separating the separators on the other surfaces of the first and second support substrates, respectively. And providing a step .

Moreover, the third method for producing a solid oxide fuel cell according to the present invention includes a thin film-like fuel electrode and an air electrode on one surface of a porous first conductive substrate. A step of forming a single cell in which an electrolyte is formed; a step of applying a conductive paste to a surface of the single cell opposite to the first support substrate; and a porous and conductive first layer. A step of applying a conductive paste on one side of the two support substrates, a step of bonding the first and second support substrates so that the conductive pastes face each other, and firing while pressing , Providing a separator on each of the other surfaces of the first and second support substrates .

  In the second and third methods, instead of using the electrolyte material paste, the electrolyte can be formed using a sheet coated with an electrolyte green body.

The fourth manufacturing method of the solid oxide fuel cell according to the present invention includes a step of forming a single cell in which a fuel electrode and an air electrode are formed on both surfaces of a thin film electrolyte, and a porous and conductive material. First and second support substrates having the above structure, sandwiching the single cell between the support substrates, firing in a pressurized state, and the first and second support substrates, respectively. And a step of providing a separator on the surface opposite to the cell .

  According to the present invention, in a fuel cell having a structure in which a single cell is supported by a support substrate, it is possible to prevent warpage of the cell when heat is applied during production or the like and to prevent damage.

  Hereinafter, position embodiments of a solid oxide fuel cell according to the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a solid oxide fuel cell according to this embodiment.

  As shown in FIG. 1, in this solid oxide fuel cell, a cell composed of an electrolyte 1, a fuel electrode 2 and an air electrode 3 having a rectangular shape in plan view is sandwiched between first and second support substrates 4 and 5. It is comprised by. The cell is configured by sandwiching the electrolyte 1 between the fuel electrode 2 and the air electrode 3. These are all formed in a thin film shape, and the thickness is preferably, for example, 1 to 100 μm. Each of the support substrates 4 and 5 is formed of a porous body and has electronic conductivity. Therefore, each support substrate 4 and 5 also serves as a current collecting layer. Moreover, since it plays the role as a board | substrate which supports a cell, it is preferable that the thickness shall be 0.2-3 mm.

  Next, materials constituting the fuel cell will be described. As the material of the electrolyte 1, those known as electrolytes for solid oxide fuel cells can be used. For example, ceria oxide doped with samarium or gadolinium, lanthanum galade doped with strontium or magnesium Oxygen ion conductive ceramic materials such as oxides, zirconia-based oxides containing scandium and yttrium can be used.

  As the fuel electrode 2, for example, a mixture of a metal catalyst and a ceramic powder material made of an oxide ion conductor can be used. As the metal catalyst used at this time, a material that is stable in a reducing atmosphere such as nickel, iron, cobalt, or a noble metal (platinum, ruthenium, palladium, etc.) and has hydrogen oxidation activity can be used. In addition, as the oxide ion conductor, one having a fluorite structure or a perovskite structure can be preferably used. Examples of those having a fluorite structure include ceria-based oxides doped with samarium, gadolinium, and the like, and zirconia-based oxides containing scandium and yttrium. In addition, examples of those having a perovskite structure include lanthanum galide oxides doped with strontium and magnesium. Among the above materials, it is preferable to form the fuel electrode with a mixture of an oxide ion conductor and nickel. The mixed form of the ceramic material made of the oxide ion conductor and nickel may be a physical mixed form or a form of powder modification to nickel. Moreover, the ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types. The fuel electrode can also be configured using a metal catalyst alone.

As the ceramic powder material forming the air electrode 3, for example, a metal oxide made of Co, Fe, Ni, Cr, Mn or the like having a perovskite structure or the like can be used. Specifically, (Sm, Sr) CoO ₃ , (La, Sr) MnO ₃ , (La, Sr) CoO ₃ , (La, Sr) (Fe, Co) O ₃ , (La, Sr) (Fe, Co , Ni) O _{3 and the} like, and (La, Sr) MnO ₃ is preferable. The ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types.

The support substrates 4 and 5 are made of conductive metal such as Pt, Au, Pd, Ag, Ni, Cu, SUS (stainless steel), Inconel, or La (Cr, Mg) O ₃ , (La, Ca) CrO. ₃ , (La, Sr) CrO ₃ and other conductive ceramic materials such as lanthanum and chromite. One of these may be used alone, or two or more may be mixed. May be used. In general, dry pressure molding is used for forming the support substrates 4 and 5, but it is not necessary to specify this, and the support substrates 4 and 5 can be manufactured using extrusion molding, injection molding, casting molding, or the like. . The support substrates 4 and 5 thus manufactured preferably have a porosity of 20 to 60%. This is because if it is less than 20%, it becomes difficult to supply the fuel gas and the oxidant gas to the electrode, while if it exceeds 60%, the current collecting ability decreases.

  The average particle size of the ceramic powder that is a raw material for the electrolyte 1, the fuel electrode 2, and the air electrode 3 is preferably 10 nm to 100 μm, more preferably 50 nm to 50 μm, and particularly preferably 100 nm to 10 μm. In addition, an average particle diameter can be measured according to JISZ8901, for example.

  As a method for forming the electrolyte 1, the fuel electrode 2, and the air electrode 3, for example, a printing method can be used, and specifically, a printing method such as a screen printing method, a knife coating method, a doctor blade method, or a spray coating method. Can be used. In addition to this, the powder material forming the fuel electrode 2 and the air electrode 3 is mixed with a binder, applied on a sheet (so-called green body), and these are transferred to form an electrode. it can.

  When the fuel electrode 2 and the air electrode 3 are printed and formed, first, a paste of the fuel electrode and the air electrode is prepared. It is formed by adding an appropriate amount of a binder resin, an organic solvent, etc. with the above-described material as a main component. More specifically, it is preferable to add a binder resin or the like so that the main component is 50 to 95% by weight in the mixing of the main component and the binder resin. In addition, when the electrolyte is also formed by printing, as in the case of the fuel electrode and the air electrode, it is formed by adding an appropriate amount of a binder resin, an organic solvent, etc. with the above-mentioned material as the main component. Is preferably mixed so that the ratio of the main component is 80% by weight or more.

  The binder described above includes an organic resin and a solvent. The organic resin contained in the binder needs to be combusted / decomposed / vaporized at a low temperature during the baking process, and a thermoplastic resin such as an acrylic resin, a styrene resin, an ethyl cellulose derivative, or a styrene acrylic copolymer is used alone. Or it can be mixed and used.

  As the organic solvent, ketones, esters, ethers, amides, etc. can be used alone or in combination. Specifically, isopropanol, normal propanol, diacetone alcohol, glycol diacetate. , Methyl cellosolve, carbitol, cyclohexane, terpineol and the like can be used. As the solvent, compounds such as glycerin, dibutyl phthalate and dioctyl phthalate can be used.

  The fuel cell configured as described above generates power as follows. That is, a mixed gas of a fuel gas composed of hydrogen or a hydrocarbon such as methane or ethane and an oxidant gas such as air is supplied to the battery at a high temperature (for example, 400 to 1000 ° C.). Since the electrodes 2 and 3 and the support substrates 4 and 5 are porous, the supplied mixed gas comes into contact with the fuel electrode 2 and the air electrode 3 through the support substrates 4 and 5. Oxygen ion conduction occurs between the electrode 3 and the electrolyte 1 to generate electricity. Note that the fuel gas and the oxidant gas may be supplied separately instead of supplying the mixed gas. In this case, known separators having grooves formed on the surface are respectively disposed on the support substrates 4 and 5, and two gases are supplied to the groove portions of the respective separators. Thereby, without mixing each gas, while fuel gas is supplied to a fuel electrode, oxidant gas is supplied to an air electrode, As a result, it is supplied and electric power generation is performed.

  As described above, the fuel cell according to this embodiment has a structure in which a cell including the electrolyte 1, the fuel electrode 2, and the air electrode 3 is sandwiched between the pair of support substrates 4 and 5 made of the same material. Therefore, even if there is a difference in thermal expansion coefficient between the cell and the support substrate, since the cell is sandwiched between the support substrates 4 and 5 having the same thermal expansion coefficient, for example, when firing is performed during manufacturing In addition, the cell can be prevented from warping or deforming. As a result, cell damage can be prevented.

  Further, as described above, since the cell is sandwiched between the pair of support substrates 4 and 5, the support substrates 4 and 5 also serve to protect the cell. Therefore, this also prevents cell damage.

  Next, a method for manufacturing the fuel cell configured as described above will be described. This fuel cell can be manufactured using various methods such as a printing method and a transfer method.

Printing method 1 (see Fig. 2)
(1) A fuel electrode material paste is printed on one surface of the first support substrate 4, dried, and then fired at 800 to 1500 ° C. for 1 to 10 hours to form the fuel electrode 2.
(2) The electrolyte material paste is printed on the fuel electrode 2, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the electrolyte 1.
(3) The air electrode material paste is printed on the second support substrate 5, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the air electrode.
(4) The first and second support substrates 4 and 5 are bonded together so that the electrolyte 1 and the air electrode 3 face each other, and are pressed at 800-1500 ° C. while being pressurized by the weight of the support substrate. Bake for ~ 10 hours.
Through the above steps, a solid oxide shaped battery is completed.

Printing method 2
(1) A fuel electrode material paste is printed on one surface of the first support substrate 4, dried, and then fired at 800 to 1500 ° C. for 1 to 10 hours to form the fuel electrode 2.
(2) The air electrode material paste is printed on the second support substrate 5, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the air electrode 3.
(3) The electrolyte material paste is printed on the air electrode 3, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the electrolyte 1.
(4) The first and second support substrates 4 and 5 are bonded together so that the fuel electrode 2 and the electrolyte 1 face each other and pressed by weight or the like, and fired at 800 to 1500 ° C. for 1 to 10 hours. To do.
Through the above steps, a solid oxide shaped battery is completed.

Printing method 3
(1) A fuel electrode material paste is printed on one surface of the first support substrate 4, dried, and then fired at 800 to 1500 ° C. for 1 to 10 hours to form the fuel electrode 2.
(2) The electrolyte material paste is printed on the fuel electrode 2, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the electrolyte 1.
(3) The air electrode paste is printed on the second support substrate 5, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the air electrode.
(4) A mixed paste obtained by mixing the electrolyte material paste and the air electrode material paste is prepared and printed on the electrolyte 1 of the first support substrate 4.
(5) The mixed paste prepared in (4) above is printed on the air electrode 3 of the second support substrate 5.
(6) The first and second support substrates 4 and 5 are bonded together so that the mixed pastes face each other, and thermocompression bonded under conditions of 100 ° C. and 30 kg / cm ² . Thereafter, it is baked at 800-1500 ° C. for 1-10 hours in a state of being pressurized with a weight or the like.
Through the above steps, a solid oxide shaped battery is completed.

Printing method 4
(1) A fuel electrode material paste is printed on one surface of the first support substrate 4, dried, and then fired at 800 to 1500 ° C. for 1 to 10 hours to form the fuel electrode 2.
(2) The air electrode material paste is printed on the second support substrate 5, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the air electrode 3.
(3) The electrolyte material paste is printed on the air electrode 3, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the electrolyte 1.
(4) A mixed paste obtained by mixing the electrolyte material paste and the fuel electrode paste is prepared and printed on the fuel electrode 2 of the first support substrate 4.
(5) The mixed paste prepared in (4) above is printed on the electrolyte 1 of the second support substrate 5.
(6) The first and second support substrates 4 and 5 are bonded together so that the mixed pastes are opposed to each other and thermocompression bonded. Thereafter, firing is performed at 800 to 1500 ° C. for 1 to 10 hours while pressing with a weight or the like.
Through the above steps, a solid oxide shaped battery is completed.

Printing method 5
(1) A fuel electrode material paste is printed on one surface of the first support substrate 4, dried, and then fired at 800 to 1500 ° C. for 1 to 10 hours to form the fuel electrode 2.
(2) The air electrode material paste is printed on the second support substrate 5, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the air electrode 3.
(3) An electrolyte material paste is printed on the fuel electrode 2.
(4) The electrolyte material paste is printed on the air electrode 3.
(5) The first and second support substrates 4 and 5 are bonded and thermocompression bonded so that the electrolyte material pastes face each other. Thereafter, it is baked at 800-1500 ° C. for 1-10 hours in a state of being pressurized with a weight or the like.
Through the above steps, a solid oxide shaped battery is completed.

Printing method 6
(1) A fuel electrode material paste is printed on one surface of the first support substrate 4, dried, and then fired at 800 to 1500 ° C. for 1 to 10 hours to form the fuel electrode 2.
(2) The electrolyte material paste is printed on the fuel electrode 2, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the electrolyte 1.
(3) The air electrode material paste is printed on the electrolyte 1, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the air electrode 3.
(4) A conductive paste having electronic conductivity such as Au is prepared and printed on the air electrode 3.
(5) Print the conductive paste prepared in (4) on the second support substrate 5.
(6) The first and second support substrates 4 and 5 are bonded and thermocompression bonded so that the conductive pastes face each other. Thereafter, it is baked at 1000 ° C. for 1 hour in a state of being pressurized by a weight or the like.
Through the above steps, a solid oxide shaped battery is completed.

Printing method 7
(1) The air electrode material paste is printed on one surface of the first support substrate 4, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the air electrode 3.
(2) The electrolyte material paste is printed on the air electrode 3, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form the electrolyte 1.
(3) A fuel electrode material paste is formed by printing a fuel electrode material paste on the electrolyte 1 and drying it, followed by firing at 800-1500 ° C. for 1-10 hours.
(4) A conductive paste having electronic conductivity such as Au is prepared and printed on the fuel electrode 2.
(5) Print the conductive paste prepared in (4) on the second support substrate 5.
(6) The first and second support substrates 4 and 5 are bonded and thermocompression bonded so that the conductive pastes face each other. Thereafter, it is baked at 1000 ° C. for 1 hour in a state of being pressurized by a weight or the like.
Through the above steps, a solid oxide shaped battery is completed.

Tape casting method
(1) The fuel electrode, electrolyte, and air electrode were made into sheets for each electrode and electrolyte using the tape casting method. Each sheet was produced by printing and drying each electrode / electrolyte paste on a ceramic sheet using a doctor blade.
(2) The fuel electrode sheet produced by the tape casting method is thermocompression-bonded on the first support substrate 4, and then the electrolyte sheet produced by the tape casting method is thermocompression-bonded, followed by 1 at 800 to 1500 ° C. Co-sintering is performed for ˜10 hours to form the fuel electrode 2 and the electrolyte 1.
(3) After the air electrode sheet produced by the tape casting method is thermocompression-bonded on the second support substrate 5, the air electrode 3 is formed by baking at 800 to 1500 ° C. for 1 to 10 hours.
(4) The first and second support substrates 4 and 5 are bonded and thermocompression bonded so that the electrolyte 1 and the air electrode 3 face each other. Thereafter, it is baked at 800-1500 ° C. for 1-10 hours in a state of being pressurized with a weight or the like.
Through the above steps, a solid oxide shaped battery is completed.

  Various variations of this method are possible, and a battery can be manufactured by the same method as the printing methods 2 to 7 described above. That is, a battery can be produced through the same procedure as in printing methods 2 to 7, using a sheet produced by a tape casting method instead of the material paste in printing methods 2 to 7.

Vacuum forming method
(1) A fuel electrode material paste is printed on one surface of the first support substrate 4, dried, and then fired at 800 to 1500 ° C. for 1 to 10 hours to form the fuel electrode 2.
(2) The electrolyte 1 is formed on the fuel electrode 2 by a vacuum method such as vacuum deposition or sputtering.
(3) An air electrode paste is printed on the second support substrate 5, dried, and then baked at 800 to 1500 ° C. for 1 to 10 hours to form an air electrode.
(4) The first and second support substrates 4 and 5 are bonded so that the electrolyte 1 and the air electrode 3 face each other, and baked at 800 to 1500 ° C. for 1 to 10 hours while being pressed by weight. .
Through the above steps, a solid oxide shaped battery is completed.

  Various variations of this method are possible, and not only the electrolyte 1 but also the electrodes 2 and 3 can be formed by the above-described vacuum method. The electrolyte and the electrode can be formed by other methods, for example, a solution method such as electrostatic spraying or electrodeposition.

1 is a cross-sectional view showing an embodiment of a solid oxide fuel cell according to the present invention. It is a figure which shows an example of the manufacturing method of the solid oxide fuel cell of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrolyte 2 Fuel electrode 3 Air electrode 4 1st support substrate 5 2nd support substrate

Claims (6)

A thin-film electrolyte;
A thin-film fuel electrode disposed on one surface of the electrolyte;
A thin film air electrode disposed on the other surface of the electrolyte;
A pair of support substrates disposed on surfaces of the fuel electrode and the air electrode opposite to the electrolyte; and
A pair of separators disposed on the surface of each supporting substrate opposite to the fuel electrode or air electrode,
Each of the supporting substrates is porous and conductive, and is bonded to a fuel electrode or an air electrode by firing, and is a solid oxide fuel cell. 2. The solid oxide fuel cell according to claim 1 , wherein the electrolyte, the fuel electrode, and the air electrode have a thickness of 1 to 100 μm. Forming a thin film-like fuel electrode on one surface of a porous and electrically conductive first support substrate;
Forming a thin film-like air electrode on one surface of a porous and conductive second support substrate;
Forming a thin film electrolyte on the fuel electrode or the air electrode;
Bonding the first and second support substrates so that the electrolyte and the fuel electrode or air electrode face each other, and firing in a pressurized state;
Providing a separator on each of the other surfaces of the first and second support substrates;
A method for producing a solid oxide fuel cell comprising: Forming a thin film-like fuel electrode on one surface of a porous and electrically conductive first support substrate;
Forming a thin film-like air electrode on one surface of a porous and conductive second support substrate;
Applying an electrolyte material paste for forming an electrolyte to each of the fuel electrode and the air electrode;
Bonding the first and second support substrates so that the electrolyte material pastes face each other, and firing in a pressurized state;
Providing a separator on each of the other surfaces of the first and second support substrates;
A method for producing a solid oxide fuel cell. Forming a single cell in which an electrolyte is formed between a thin film fuel electrode and an air electrode on one surface of a porous and conductive first support substrate;
In the single cell, a step of applying a conductive paste on a surface opposite to the first support substrate;
Applying a conductive paste on one side of a porous and conductive second support substrate;
Bonding the first and second support substrates so that the conductive pastes face each other, and firing in a pressurized state;
Providing a separator on each of the other surfaces of the first and second support substrates;
A method for producing a solid oxide fuel cell. Forming a single cell in which a fuel electrode and an air electrode are formed on both surfaces of a thin-film electrolyte; and
Preparing porous and electrically conductive first and second support substrates, sandwiching the single cell between the first and second support substrates, and firing in a pressurized state;
In the first and second support substrates, a step of providing a separator on the surface opposite to the single cell,
A method for producing a solid oxide fuel cell.

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