JP2006221884A - Single chamber type solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single chamber type solid oxide fuel cell of which the output improvement can be achieved by preventing the internal short-circuit phenomenon, and by thinning an electrolyte. <P>SOLUTION: This is the single chamber type solid oxide fuel cell 1 in which a plurality of members of single cells 5 provided with a sheet-like electrolyte 2, a fuel electrode 3 formed on the front side of the electrolyte 2, and an air electrode 4 formed on the back side of the electrolyte 2 have been connected in series. The adjacent single cells 5 ... are aligned and arranged in the face direction faced opposed to each other, those adjacent single cells 5 are coupled to each other under the interposition of an adhesive layer 8, and the air electrode 4 of one side of the adjacent single cells 5 and the fuel electrode 3 of the other side of the single cells 5 ... have been connected by an inter connector 6 so that the adjacent single cells 5 ... will be connected in series. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a single-chamber solid oxide fuel cell in which a fuel electrode and an air electrode are formed on a solid oxide electrolyte, and power is generated by a mixed gas of fuel gas and oxidant gas.

  Conventionally, as this type of single-chamber solid oxide fuel cell, one in which an air electrode and a fuel electrode are formed on one surface of an electrolyte substrate is known (see, for example, Patent Documents 1 and 2). Since the single chamber type solid oxide fuel cell has a small output per unit cell, a plurality of unit cells are connected in series. Therefore, the thing of the structure which printed and formed the fuel electrode and the air electrode alternately on the electrolyte sheet, and connected in series by the interconnector (for example, patent document 2).

Also, when forming a plurality of single cells by forming a plurality of holes in an insulating support substrate, inserting an electrolyte green sheet into the holes, and printing the air electrode and the fuel electrode from both sides so as to sandwich the electrolyte In addition, the air electrode and the fuel electrode are adjacent to each other on one side, and the adjacent air electrode and the fuel electrode are connected by an interconnector so as to connect the single cells in series (for example, Patent Document 3). It has been known.
JP 2002-280015 A JP-A-8-264195 JP 2003-51319 A

  However, in the invention described in Patent Document 2, since a plurality of fuel electrodes and air electrodes are formed on one surface of the electrolyte, the surface of the electrolyte becomes a movement path of oxygen ions during power generation, and the original single cell Since the electromotive force and the electromotive force of the battery formed between the single cells cancel each other and an internal short circuit occurs, the electromotive force of the entire fuel cell is lowered, and the battery performance may be lowered.

  Further, in the invention described in Patent Document 3, since the electrolyte is sandwiched between the fuel electrode and the air electrode, it is necessary to make the electrolyte as thin as possible in order to increase the output. In addition, since there is a limit to thinning the substrate in order to obtain strength as a substrate, improvement in output is limited.

  Furthermore, in the invention described in Patent Document 3, since the electrolyte green sheet shrinks after sintering, a gap is easily generated between the inner wall of the through hole of the support substrate and the peripheral wall of the electrolyte. Various problems such as cracks due to thermal expansion of air in the gap space and migration due to moisture intrusion can occur.

  Therefore, a main object of the present invention is to provide a single-chamber solid oxide fuel cell capable of preventing a decrease in electromotive force due to the internal short-circuit phenomenon and reducing the thickness of the electrolyte.

  In order to achieve the above object, a single-chamber solid oxide fuel cell according to the present invention comprises a single-plate electrolyte, a fuel electrode formed on the front side of the electrolyte, and an air electrode formed on the back side of the electrolyte. A plurality of cells are single-chamber solid oxide fuel cells connected in series, and the adjacent single cells are arranged side by side in the surface direction opposite to each other, and the adjacent single cells are adhesive layers. The air electrode of one of the adjacent single cells and the fuel electrode of the other single cell are connected by an interconnector so that the adjacent single cells are connected in series. .

  In the adjacent single cells, the respective electrolytes may be connected by an adhesive layer.

  The adjacent single cells may be supported by a support substrate, the support substrate may be a porous body having mixed gas permeability, and the single cells may be bonded to the support substrate by the adhesive layer. . The plurality of single cells may be accommodated in a plurality of recesses formed on the support substrate of the porous body.

  Further, the adjacent single cells are supported by a support substrate, and the support substrate is formed with a through hole for bringing the fuel electrode or the air electrode into contact with the mixed gas, and the single cell is the adhesive layer. May be adhered to the support substrate. In this case, the support substrate has a plurality of through holes for receiving the plurality of single cells, and a step portion is formed on the inner wall surface of the through hole, and the step portion forms a peripheral portion of the single cell. May be supported, and the peripheral edge portion may be bonded to the stepped portion by the adhesive layer.

  It is preferable that the peripheral part of the said single cell supported by the said step part is an electrolyte.

  It is preferable that the depth dimension of the step portion is equal to the thickness dimension of the electrolyte.

  It is preferable that the support substrate is formed with partition walls for separating adjacent single cells from each other.

  According to the single-chamber solid oxide fuel cell according to the present invention, a plurality of single cells in which the air electrode is sintered on one side of the electrolyte and the fuel electrode is sintered on the other side are arranged in the plane direction, and the adhesive layer is used. Directly connected or indirectly connected by an adhesive layer via a support substrate, etc., and connected in series by an interconnector, so the thickness of the electrolyte is not limited by the support substrate, so output reduction due to internal short circuit phenomenon The output can be improved by reducing the thickness of the electrolyte.

  Preferred embodiments of a single-chamber solid oxide fuel cell (hereinafter simply referred to as “fuel cell”) according to the present invention will be described below with reference to the drawings. In addition, the same code | symbol was attached | subjected to the same component through the whole figure.

  First, a first embodiment of a fuel cell according to the present invention will be described with reference to FIGS. 1 is a plan view showing the front side, FIG. 2 is a bottom view showing the back side, and FIG. 3 is a cross-sectional view taken along line III-III in FIG.

  The fuel cell 1 of the first embodiment includes a thin plate-like electrolyte 2, a fuel electrode 3 formed on the front side of the electrolyte 2, and two unit cells 5, 5 including an air electrode 4 formed on the back side of the electrolyte 2. Are connected in series by the interconnector 6.

  Adjacent single cells 5 and 5 are arranged side by side in the surface direction opposite to each other, and the air electrode 4 of one single cell 5 and the other single cell 5 are connected in series so that the adjacent single cells 5 and 5 are connected in series. The fuel electrode 3 of the cell 5 is connected by an interconnector 6.

  At both ends of the fuel cell 1, a current collector 7 for taking out electric power is provided, and the current collector 7 is connected to the air electrode 4 and the fuel electrode 3 that are not connected by the interconnector 6.

  The electrolytes 2 and 2 are connected to each other by an adhesive layer 8. The adhesive layer 8 can be formed of an inorganic adhesive. For example, Aron ceramics manufactured by Toa Gosei Co., Ltd. can be used.

  The single cell 5 can be manufactured according to the standard method of this type of fuel cell, and a plurality of single cells 5, 5 are connected by connecting previously manufactured single cells by an adhesive layer 8 and connecting them in series by an interconnector 6. Can be manufactured in series. The number of single cells 5 can be increased as necessary. FIG. 4 shows an example in which four single cells are connected in series.

  Next, a second embodiment of the fuel cell according to the present invention will be described with reference to FIGS.

  Similar to the first embodiment, the fuel cell of the second embodiment includes a thin plate-like electrolyte 2, a fuel electrode 3 formed on the front side of the electrolyte 2, and an air electrode 4 formed on the back side of the electrolyte 2. Two single cells 5 are connected in series by an interconnector 6. The adjacent single cells 5 and 5 are arranged side by side in the surface direction opposite to each other, and the air electrode 4 and the other of the single cell 5 are connected in series so that the adjacent single cells 5 and 5 are connected in series. The fuel electrode 3 of each single cell 5 is connected by an interconnector 6. Furthermore, current collectors 7 for taking out electric power are provided at both ends of the fuel cell 1, and the current collectors 7 are connected to the air electrode 4 and the fuel electrode 3 that are not connected by the interconnector 6. .

  In the fuel cell 1 of the second embodiment, adjacent single cells 5 and 5 are supported by a support substrate 10.

  The support substrate 10 has a plurality of through holes 11, and a step portion 12 is formed on an inner wall surface that forms the through holes 11. The peripheral part of the single cell 5 is supported by this step part. The peripheral part of the single cell supported by the step part is the electrolyte 2 in the illustrated example.

  The peripheral edge portion of the electrolyte 2 is bonded to the step portion by the adhesive layer 8. Such an adhesive layer 8 can be formed of the same inorganic adhesive as in the first embodiment.

  It is preferable that the depth dimension of the stepped portion 12 is equal to the thickness dimension of the electrolyte 2. By doing so, it becomes easy to form the interconnector 6 formed by a printing method or the like.

  The support substrate 10 preferably forms a partition wall 13 for separating the electrolytes of the adjacent single cells 5 and 5 from each other.

  In such a fuel cell according to the second embodiment, a plurality of single cells manufactured in advance according to a conventional method are placed on the step 12 of the support substrate 10 and adhered by the adhesive layer 8, and the interconnector 6 and the current collector 7 are connected. Manufactured by forming by printing or the like.

  5 to 7 show examples of two single cells, the number can be increased as necessary. FIG. 8 shows an example in which four single cells are connected in series.

  FIG. 9 shows a third embodiment of the fuel cell according to the present invention. In the fuel cell shown in FIG. 9, the support substrate 10 is formed with a through hole 11 for contacting the mixed gas with the fuel electrode 3 or the air electrode 4, and the step portion is not formed. Is different. The peripheral portion of the electrolyte 2 of the single cells 5 and 5 is bonded to the support substrate 10 via the adhesive layer 8. The fuel electrode 3 and the air electrode 4 are formed so as to fit within the through hole 11. That is, the through hole 11 formed in the support substrate 10 has an opening area equivalent to the occupied area on the electrolyte of the air electrode 3 and the fuel electrode 4.

  It is known that the conductivity of a solid electrolyte is about an order of magnitude lower than the conductivity of electrolytes of phosphoric acid fuel cells and molten carbonate fuel cells. In general, since the electric resistance of the electrolyte portion is a power generation loss, in order to improve the power generation output density, it is important to reduce the film resistance as much as possible by reducing the thickness of the solid electrolyte.

  In the first to third embodiments, the support substrate 10 has shown a form for supporting both ends of the electrolyte. However, the support substrate 10 is not limited to this, and from the standpoint that it is more preferable to make the electrolyte thinner, the following description will be given. 4. It can be set as the form shown in the fifth embodiment.

  FIG. 10 shows a fourth embodiment of the fuel cell according to the present invention. In the fuel cell 1 shown in FIG. 10, two single cells 5, 5 are mounted on a porous support substrate 10, and the single cells 5, 5 are bonded to the support substrate 10 by an adhesive layer 8, thereby supporting the support substrate 10. 10 are connected. In the single cells 5 and 5, the periphery of the electrolyte 2 is bonded to the support substrate 10 via the adhesive layer 8.

  The porous support substrate 10 has a porosity of about 20 to 50%, desirably about 30 to 40%. The mixed gas can pass through the continuous through holes of the porous support substrate 10 and come into contact with the fuel electrode 3 or the air electrode 4. By making the support substrate 10 porous and enlarging the support surface of the single cell, the single cell can be made thin. Although not shown, a recess may be formed in the porous support substrate, and a single cell may be accommodated in the recess.

  FIG. 11 shows a fifth embodiment of the fuel cell according to the present invention. A plurality of through holes 11 are formed in the support substrate 10. The through hole 11 is formed at least in a region where the fuel electrode 3 and the air electrode 4 face. The porosity by the through holes 11 of the support substrate 10 in the region can be the same as that of the fourth embodiment. In the fifth embodiment, in the support substrate 10, the portion where the through holes 11 are not formed in the region where the plurality of through holes 11 are formed functions as a support surface of the single cells 5, 5. Can be made thinner.

  As described above, a cell in which a fuel electrode, an electrolyte, and an air electrode are stacked in this order is disposed on a support substrate capable of gas permeation, and at least the cell is divided into a plurality of cells, and the support substrate is an electrode. By making it a separate body without serving as both, it is possible to optimize the material in consideration of the difference in thermal expansion coefficient from the electrode layer and the electrolyte layer, and to improve heat resistance and thermal shock resistance.

  Next, the material of the fuel cell configured as in the first and second embodiments will be described. As the material of the electrolyte 2, 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, etc. Oxygen ion conductive ceramic materials such as oxides, zirconia-based oxides containing scandium and yttrium can be used.

  The fuel electrode 3 and the air electrode 4 can be formed of a ceramic powder material. The average particle size of the powder used at this time 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 the fuel electrode 3, 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 3 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. Moreover, the fuel electrode 3 can also be comprised using a metal catalyst alone.

As the ceramic powder material forming the air electrode 4, 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 interconnector 6 and the current collector 7 are made of conductive metal such as Pt, Au, Ag, Ni, Cu, and SUS, or a metal-based material, 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.

  The fuel electrode 3 and the air electrode 4 are formed by adding appropriate amounts of a binder resin, an organic solvent, and the like with the above-described materials as main components. 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. Further, the interconnector 6 and the current collector 7 are also formed by adding the above additives to the above-described materials. The current collector 7 may be formed of a conductive metal, a wire made of a metal-based material, a mesh-like material, or the like.

  As a material of the support substrate 10, a general heat-resistant glass such as quartz glass or Vycor glass, or a ceramic plate such as alumina, silicon nitride, or silicon carbide can be used. In addition, when the support substrate 10 is in contact with only the electrolyte and the adhesive layer without being in contact with the fuel electrode and the air electrode, a silicon wafer or a metal having nickel or iron as a main component that exhibits cell conductivity in the fuel cell operating temperature range. Also, a metal plate such as SUS can be used, and a current collecting effect can also be imparted.

Example 1
Single Cell Fabrication Method A solid oxide fuel cell having the structure shown in FIG. 1 was fabricated. As an electrolyte material, GDC (Ce _0.9 Gd _0.1 O _1.9 ) powder (average particle size 0.5 μm) was used. First, the electrolyte powder was placed in a pressure vessel, molded with a uniaxial press at a pressure of 1 t / cm ² , packaged in a vacuum pack, and molded again with a hydrostatic pressure press at a pressure of ² t / cm ² . Then, sintering (1450 degreeC, 10 hours) was performed, and the electrolyte plate was produced. The dimensions and thickness were formed to be 0.9 mm □ × 0.4 mm with a ceramic cutter.

Nickel oxide (NiO) powder (average particle size 0.5 μm) and SDC (Ce _0.8 Sm _0.2 O _1.9 ) powder (average particle size 1 μm) were used as the fuel electrode material.

Sm _0.5 Sr _0.5 CoO ₃ (average particle size 3 μm) was used as the air electrode material.

  The fuel electrode and air electrode powder pastes were prepared.

As the fuel electrode paste, NiO and SDC powder are mixed so that the weight ratio is 7: 3, ethyl cellulose is used as a binder, ethyl carbitol is used as a solvent, and these are mixed and dispersed by a ball mill. The viscosity of the paste was 5 × 10 ⁵ mPa · s.

As an air electrode paste, Sm _0.5 Sr _0.5 CoO ₃ powder, ethyl cellulose as a binder, and ethyl carbitol as a solvent are mixed, and these are mixed and dispersed by a ball mill, so that the viscosity of the paste is 5 × 10 ⁵ mPa · s.

  Next, the fuel electrode paste was printed on the electrolyte substrate 0.9 mm □, and the screen was printed at 0.7 mm □ in the center of the electrolyte substrate. After printing, the coating thickness was adjusted to be 50 μm after drying in an oven at 130 ° C. for 15 minutes. Thereafter, baking was performed at 1450 ° C. for 1 hour.

  Subsequently, similarly to the fuel electrode, printing was performed on the opposite surface on which the electrolyte electrode layer of 0.9 mm □ was formed using a screen printing method so that the central portion of the electrolyte substrate was 0.7 mm □. After printing, the coating thickness was adjusted to be 50 μm after drying in an oven at 130 ° C. for 15 minutes. Thereafter, baking was performed at 1200 ° C. for 1 hour.

  A solid oxide fuel cell single cell composed of a fuel electrode / electrolyte substrate / air electrode was produced by the above-described process.

Two-cell production method Two single cells were prepared. Alumina-based adhesive (Aron Ceramics D manufactured by Toa Gosei Co., Ltd.) is applied to the walls of the two flat cells with a brush, left at room temperature for 16 hours, heated at 90 ° C for 1 hour, and then heated at 150 ° C for 1 hour. Then, two single cells were connected (from the Toagosei manual).

  On the other hand, Au powder (average particle size 2.5 μm) was used as a material for the interconnector. This was made into a paste by the same method as the paste for the fuel electrode and the air electrode.

  The interconnector paste was printed using screen printing so as to connect the fuel electrode of one cell and the air electrode of the other cell as shown in FIGS. After printing, the coating thickness was adjusted to 10 μm after drying in an oven at 130 ° C. for 15 minutes. Thereafter, firing was performed at 1000 ° C. for 1 hour.

  Further, an interconnector paste was formed on the electrode on the side where the interconnector was not printed as a current outlet by the same method as described above.

  Through the above steps, a solid oxide fuel cell having a structure in which two single cells are connected in series as shown in FIGS.

Example 2
The single cell is manufactured in the same manner as in the first embodiment.

  An alumina plate (thickness 0.8 mm) was processed to produce a support substrate as shown in FIGS. A blasting method was used for processing the alumina substrate. An abrasive (zirconia powder) was prepared, and a mask was used to form the abrasive by jetting the abrasive only on the processed surface of alumina.

  Next, an adhesive was applied to the step portion (L-shaped portion) of the alumina plate with a brush, and then a single cell was placed to bond the substrate and the single cell.

  Subsequently, an interconnector was formed as described above, and a solid oxide fuel cell having a structure in which two single cells were connected in series as shown in FIGS.

It is a top view which shows the front side of 1st Embodiment of the single chamber type solid oxide fuel cell which concerns on this invention. It is a top view which shows the back side of the fuel cell of FIG. It is the III-III line longitudinal cross-sectional view of FIG. It is a longitudinal cross-sectional view which shows the change aspect of the fuel cell of FIG. It is a top view which shows the front side of 2nd Embodiment of the single chamber type solid oxide fuel cell which concerns on this invention. It is a top view which shows the back side of the fuel cell of FIG. It is the VII-VII sectional view taken on the line of FIG. It is a longitudinal cross-sectional view which shows the change aspect of the fuel cell of FIG. It is a longitudinal cross-sectional view which shows 3rd Embodiment of the fuel cell which concerns on this invention. It is a longitudinal cross-sectional view which shows 4th Embodiment of the fuel cell which concerns on this invention. It is a longitudinal cross-sectional view which shows 5th Embodiment of the fuel cell which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Single-chamber solid oxide fuel cell 2 Electrolyte 3 Fuel electrode 4 Air electrode 5 Single cell 6 Interconnector 7 Current collecting part 8 Adhesive layer 10 Support substrate 11 Through-hole 12 Step part 13 Partition part

Claims (9)

A single-chamber solid oxide fuel cell in which a plurality of unit cells each including a thin plate-shaped electrolyte, a fuel electrode formed on the front surface of the electrolyte, and an air electrode formed on the back side of the electrolyte are connected in series. ,
The adjacent single cells are arranged side by side in the surface direction opposite to each other, the adjacent single cells are connected under the adhesive layer, and the adjacent one cells are connected in series so that the adjacent single cells are connected in series. A single-chamber solid oxide fuel cell, wherein an air electrode of a single cell and a fuel electrode of the other single cell are connected by an interconnector. 2. The single-chamber solid oxide fuel cell according to claim 1, wherein the electrolytes of the adjacent unit cells are connected to each other by an adhesive layer. The adjacent single cells are supported by a support substrate, the support substrate is a porous body having mixed gas permeability, and the single cells are bonded to the support substrate by the adhesive layer. The single-chamber solid oxide fuel cell according to claim 1. 4. The single-chamber solid oxide fuel cell according to claim 3, wherein the plurality of single cells are accommodated in a plurality of recesses formed in a support substrate of the porous body. The adjacent single cells are supported by a support substrate, and the support substrate is formed with through holes for bringing the fuel electrode or air electrode into contact with the mixed gas, and the single cells are formed by the adhesive layer. The single-chamber solid oxide fuel cell according to claim 1, wherein the single-chamber solid oxide fuel cell is bonded to a support substrate. The support substrate has a plurality of through holes for receiving the plurality of single cells, and a step portion is formed on an inner wall surface of the through hole, and a peripheral portion of the single cell is supported by the step portions. 6. The single-chamber solid oxide fuel cell according to claim 5, wherein the peripheral edge portion is bonded to the step portion by the adhesive layer. The single-chamber solid oxide fuel cell according to claim 6, wherein a peripheral portion of the single cell supported by the step portion is an electrolyte. The single chamber type solid oxide fuel cell according to claim 6, wherein a depth dimension of the stepped portion is equal to a thickness dimension of the electrolyte. The single-chamber solid oxide fuel cell according to claim 4 or 6, wherein the support substrate is formed with partition walls for separating adjacent single cells from each other.

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