JP2009064632A - Solid oxide fuel cell and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell assuring high sealability when forming gas sealing by using a sheet or the like, and also to provide a method for manufacturing the same. <P>SOLUTION: In a conductive member 13, a gas seal layer 15 is joined so as to cover both end surfaces of an axial direction of a fuel cell tube 3, and the gas seal layer 15 consists of a first seal layer 25 of a side of the conductive member 13 and a second seal layer 27 laminated thereon. The first seal layer 25 and the second seal layer 27 are glass seal layers containing a crystal phase in a glass phase, and, in the seal layers 25 and 27, their volume ratios of the crystal phase are different respectively. Concretely, the first seal layer 25 contains glass as a principal component and a ceramic component of 5 to 40 vol.% as the crystal phase. On the other hand, the second seal layer 27 contains glass as a principal component and a ceramic component of 0 to 15 vol.% as the crystal phase. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell in which different gases (fuel gas, oxidant gas) are introduced therein and electric power is generated using characteristics of a solid electrolyte, and a method for manufacturing the same.

Conventionally, a solid oxide fuel cell (solid oxide fuel cell) using a solid electrolyte (solid oxide) is known as a fuel cell.
As this solid oxide fuel cell, for example, a battery using a plurality of plate-like cells each provided with a fuel electrode and an air electrode on each surface of a solid electrolyte layer is known. In addition to the plate-like body, a cylindrical body in which a solid electrolyte layer is formed outside a cylindrical air electrode (inner electrode) and a fuel electrode (outer electrode) is further formed outside the solid electrolyte layer is proposed. ing.

  In the above-described solid oxide fuel cell, since a fuel gas (for example, hydrogen) and an oxidant gas (for example, air) are used, it is necessary to provide a gas seal at the joint portion of the member so that these gases do not leak. However, since the solid oxide fuel cell is generally operated at a high temperature of about 800 to 1000 ° C., when considering a glass seal, the heat resistant temperature of the glass is often insufficient. Specifically, since the operation is performed near the softening point of the glass, it is often difficult to maintain the shape because of the fluidity of the glass.

  Therefore, in the case of sealing with glass in a solid oxide fuel cell, studies have been made to maintain the shape by mixing ceramic powder or glass fiber with glass (see Patent Document 1). In addition, since solid oxide fuel cells with a high operating temperature are susceptible to cracking due to thermal cycles during startup and shutdown, there is also a technology for gas sealing using a glass sheet containing ceramic powder and glass fibers. It has been proposed (see Patent Document 2).

On the other hand, in order to withstand the thermal cycle at start and stop while ensuring the long-term stability of the gas seal of the solid oxide fuel cell, it is best to operate at low temperature. it is conceivable that. One way to achieve this low-temperature operation is to increase the electrode area per volume of the solid oxide fuel cell to the limit. Highly integrated fine cylindrical fuel cells as described in Patent Document 3 Technology is an effective means.
JP 2006-185775 A JP 2006-512543 A JP 2005-166470 A

  However, in the above-described solid oxide fuel cell, as a method of performing glass sealing, when glass paste is applied to the sealing portion, it is conceivable that the glass paste is screen-printed or applied by a dispenser. When there is an object, screen printing is impossible, and when the space between the fine cylindrical fuel cells is narrow, application by a dispenser is also impossible.

  In the case of a method of producing and sealing a glass sheet, firing shrinkage occurs in the glass sheet during heat treatment, or the glass sheet is easily deformed during heat treatment, and it is not easy to realize a complete gas seal.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to secure high sealing performance even when a member having a complicated shape is used, for example, when performing gas sealing using a sheet or the like. An object of the present invention is to provide a solid oxide fuel cell and a method for manufacturing the same.

  (1) The invention of claim 1 is a solid oxide fuel comprising a fuel cell constituent member constituting a solid oxide fuel cell and a gas seal layer bonded to the fuel cell constituent member and sealing gas. In the battery, the gas seal layer is composed of a plurality of seal layers mainly composed of glass, and at least one of the plurality of seal layers is a seal layer containing a crystal phase in the glass phase, The seal layer includes a first seal layer in contact with the fuel cell component and a second seal layer formed on a surface of the first seal layer, and a volume ratio of crystal phases in the first seal layer is It is larger than the volume ratio of the crystal phase in the second seal layer.

  In the present invention, at least one of the plurality of sealing layers is a layer containing a crystal phase in the glass phase, and therefore, due to the presence of the crystal phase, firing shrinkage during heat treatment is suppressed, and a desired shape can be easily obtained. . In addition, the multi-layer structure can provide many functions such as matching thermal expansion coefficients.

  In particular, in the present invention, since the volume ratio of the crystal phase of the first seal layer is larger than the volume ratio of the crystal phase of the second seal layer, it is easy to suppress deformation during firing of the first seal layer on the bonding side. At the same time, since the second seal layer is easily deformed as compared with the first seal layer, it is easy to seal the second seal layer following the first seal layer, and the second seal layer is not easily damaged. Therefore, the solid oxide fuel cell of the present invention has a high sealing performance, and has a remarkable effect that gas leakage can be effectively prevented.

Here, the glass phase indicates an amorphous phase of glass, and the crystal phase indicates a phase in which glass is crystallized and a ceramic phase.
In addition, examples of the fuel cell constituent member include a porous conductive member (a portion surrounding the fuel cell tube) constituting the fuel cell main body, but not only the fuel cell main body but also for stacking it. Examples thereof include members necessary for operating the fuel cell, such as a frame.
(2) The invention of claim 2 is characterized in that the thickness of the second seal layer is 20 to 500 μm.
This is because the followability of the second seal layer with respect to the first seal layer can be effectively obtained during the heat treatment by setting the thickness to 500 μm or less. This is because it becomes easy.

(3) The invention of claim 3 is characterized in that the constituent elements of the glass phase in the first seal layer and the second seal layer are the same.
The present invention exemplifies the structure of both seal phases, and when the glass phases are the same, there is an advantage that long-term stability is easily secured because of less element diffusion. Here, the same glass phase means the same composition.

  (4) In the invention of claim 4, the volume ratio of the crystal phases of the first seal layer and the second seal layer is changed due to the difference in the addition amount of at least one filler mixed in each of the seal layers. It is characterized by.

In this invention, the method of changing the volume ratio of a crystal phase by changing the addition amount of a filler is illustrated. Here, the filler indicates an additive such as ceramic powder.
(5) In invention of Claim 5, the addition amount of the filler of a said 1st sealing layer is 5-40 volume%, It is characterized by the above-mentioned.

  In the present invention, since the amount of filler added to the first seal layer is 5% by volume or more, deformation during firing can be suppressed, and since it is 40% by volume or less, there are many glass components and a high gas content. Sealability can be secured.

(6) In invention of Claim 6, the addition amount of the filler of a said 2nd seal layer is 0-15 volume%, It is characterized by the above-mentioned.
In the present invention, since the amount of filler added to the second seal layer is 15% by volume or less, the glass component is large, and sufficient flexibility can be ensured during heat treatment.

(7) The invention of claim 7 is characterized in that the glass has a softening point of 500 ° C. or higher.
As a sealing material for a solid oxide fuel cell, when the operating temperature of the fuel cell is taken into consideration, at least about 400 ° C. must be assumed, and considering this, glass having a softening point of 500 ° C. or higher should be used. Thereby, the effect of a gas seal is acquired. Note that the glass having a softening point sufficiently higher than the operating temperature (for example, a softening point higher by 100 ° C. or more) may be used in consideration of the operating temperature of the fuel cell.

  (8) The invention of claim 8 is characterized in that the filler is an oxide containing at least one of Al, Mg, Zr, Ce, and Si, or a mixture of these oxides.

The present invention exemplifies the types of fillers. These oxides have the advantage that their melting points are high and they are easily dispersed in the glass phase.
As the oxide, for example, Al ₂ O _3, MgO, or the like can be used _{ZrO 2, CeO 2, SiO 2} , MgAl 2 O 4, ZrSiO 4.

  (9) The invention according to claim 9 is the method for producing a solid oxide fuel cell according to any one of claims 1 to 8, wherein the paste for forming the first seal layer and the second seal layer are provided. A sheet for formation is prepared, and the sheet is closely attached to the surface of the fuel cell constituent member via the paste, and is heat-treated and bonded.

  The paste for the first seal layer used in the present invention contains a substance (for example, ceramic powder) that becomes more crystalline phase than the sheet for the second seal layer. Therefore, since the deformation | transformation at the time of baking of a paste is easy to be suppressed, since a sheet | seat is comparatively easy to deform | transform, the seal | sticker in the form which follows a paste is easy. Therefore, there is an effect that cracks are hardly generated in the second seal layer after the heat treatment.

  Therefore, according to the present invention, for example, it is easy to gas-seal a gas-sealed portion of a solid oxide fuel cell having a complicated shape such as a high-density cylindrical cell having a small diameter. Moreover, the method using this sheet and paste is a method suitable for mass production, and can perform gas sealing of a solid oxide fuel cell having a complicated shape at a low cost.

  (10) The invention of claim 10 is characterized in that the paste for forming the first seal layer and the sheet for forming the second seal layer are produced using a material in which a filler is mixed with the glass material.

In this invention, the material of paste and a sheet is illustrated and the fluidity | liquidity at the time of heat processing can be suppressed, so that there is much addition amount of a filler.
(11) The invention according to claim 11 is characterized in that the sheet for forming the second seal layer is produced by a doctor blade method.

In the present invention, it is possible to easily form a sheet by the doctor blade method, and there is an effect that gas sealing properties are easily obtained by forming the sheet.
(12) In the invention of claim 12, the paste is applied to the surface of the sheet or the temporarily fired body of the sheet, the sheet or the temporarily fired body is adhered to the fuel cell constituent member with the paste, and the glass It heat-processes at the temperature which softens, and joins the said sheet | seat or its temporary-fired body to the surface of the said fuel cell structural member.

  In the present invention, a gas seal in which thermal deformation of the sheet (and hence the second seal layer) is easily suppressed by a method in which a paste is applied to the sheet or the pre-fired body and adhered to the surface of the fuel cell constituent member and heat-treated. Can be realized.

  Here, the temporary fired body is fired at a temperature lower than the main firing in the heat treatment (for example, a temperature lower by about 50 to 100 ° C.), and thereby a harder sheet than the sheet before firing is obtained.

  (13) In the invention of claim 13, the sheet or the temporarily fired body has a through-hole through which a fuel cell tube having a cylindrical inner electrode and a solid electrolyte layer formed on the outer peripheral surface thereof penetrates. The fuel cell tube is passed through the through hole, and the sheet or the temporarily fired body thereof is joined to the surface of the fuel cell constituent member by the heat treatment.

The present invention exemplifies a sealing method adapted to the shape of the fuel cell tube. Thereby, even if it is a complicated shape, a gas seal can be carried out easily and reliably.
According to the present invention, a fuel cell tube having a cylindrical inner electrode and a solid electrolyte layer formed on the outer peripheral surface thereof is formed on the surface of a fuel cell component (for example, made of a porous conductive member). A structure penetrating the seal layer is obtained.

Hereinafter, each configuration of the solid oxide fuel cell will be described in detail.
The inner electrode and the outer electrode are used as a fuel electrode in contact with the fuel gas and an air electrode in contact with the oxidant gas serving as the oxygen source, respectively.

The “fuel electrode” is in contact with the fuel gas that is a hydrogen source and functions as a negative electrode in the single cell.
As the fuel electrode, a cermet made of metal (particularly Ni) particles and ceramic particles can be employed. In addition to Ni, Cu, Fe, Co, Ag, Pt, Pd, W, Mo, and alloys thereof can be used as the metal. Examples of the ceramic include zirconia, YSZ, ScSZ, SDC, GDC, alumina, silica, and titania. In particular, YSZ, ScSZ, SDC, and GDC are desirable. This is because they have oxygen ion conductivity and enhance the electrochemical activity of the fuel electrode.

The “air electrode” is in contact with an oxidant gas serving as an oxygen source and functions as a positive electrode in a single cell.
The material of the air electrode can be appropriately selected depending on the use conditions of the solid oxide fuel cell. As this material, for example, a metal, a metal oxide, a metal composite oxide, or the like can be used. Examples of the metal include metals such as Pt, Au, Ag, Pd, Ir, Ru, Ru, and alloys containing two or more metals.

Furthermore, examples of the metal oxide include oxides such as La, Sr, Ce, Co, Mn, and Fe (for example, La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO ₂ , FeO). Etc.). Further, as the complex oxide, various complex oxides containing at least one of La, Pr, Sm, Sr, Ba, Co, Fe, Mn, etc. (for example, La _1-x Sr _x CoO ₃ series) Complex oxides, La _1-x Sr _x FeO ₃ complex oxides, La _1-x Sr _x Co _1-y Fe _y O ₃ complex oxides, La _1-x Sr _x MnO ₃ complex oxides, Pr _1-x Ba _x CoO ₃ composite oxide, Sm _1-x Sr _x CoO ₃ composite oxide, and the like.

  -Examples of the "solid electrolyte layer" include YSZ (yttria stabilized zirconia), ScSZ (scandia stabilized zirconia), SDC (ceria doped with samaria), GDC (ceria doped with gadria), perovskite oxide, etc. It is done. These may be a single film or a multilayer film in which two or more kinds of compositions have a laminated structure. Examples of the multilayer film include a YSZ + SDC film and a YSZ + GDC film.

  The solid electrolyte layer has ionic conductivity capable of moving at least a part of one of the fuel gas introduced into the fuel electrode or the combustion-supporting gas introduced into the air electrode during operation of the fuel cell as ions. . Although what kind of ion can be conducted is not particularly limited, examples of the ion include oxygen ion and hydrogen ion.

As constituent materials of the fuel cell constituent member (for example, a porous conductive member disposed around the outer electrode), Ag, La, Sr, Mn, Co, Fe, Sm, Ce, Pr, Nd, Ca , Ba, Ni, Mg, Ti, or an oxide containing one or more of these elements can be employed. For example, La _1-x Sr _x CrO ₃ -based material (the outer electrode can be either a fuel electrode or an air electrode), La _1-x Sr _x Co _1-y Fe _y O ₃ -based material (the outer electrode is an air electrode) Only possible), La _1-x Sr _x MnO ₃ based material (only when the outside is an air electrode), Sm _1-x Sr _x CoO ₃ based material (only when the outside is an air electrode), etc. Material can be adopted.

  ・ "Fuel gas" refers to hydrogen, hydrocarbons that serve as hydrogen sources, mixed gases of hydrogen and hydrocarbons, fuel gases that have been humidified by passing these gases through water at a predetermined temperature, and water vapor mixed with these gases. Fuel gas and the like.

  The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. Further, the main components are saturated hydrocarbons having 1 to 10, preferably 1 to 7, more preferably 1 to 4 carbon atoms such as methane, ethane, propane, butane and pentane, and unsaturated hydrocarbons such as ethylene and propylene. Those having a saturated hydrocarbon as a main component are more preferable. These fuel gas may use only 1 type and can also use 2 or more types together. Moreover, you may contain inert gas, such as nitrogen and argon.

  -"Oxidant gas" includes a mixed gas of oxygen and other gases. The mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon. Of these flammable gases, air (containing about 80% by volume of nitrogen) is preferred because it is safe and inexpensive.

Examples of embodiments of the present invention will be described below.
[Embodiment]
Here, as a solid oxide fuel cell, a cube-shaped solid oxide fuel cell stack (hereinafter also simply referred to as a fuel cell cube) in which a large number of solid oxide fuel cells (single cells) are integrated and its manufacture A method will be described.

a) First, the overall configuration of the fuel cell cube of this embodiment will be described.
As shown in FIG. 1, in the fuel cell cube 1 of the present embodiment, a fuel cell layered portion 5 in which a large number of cylindrical fuel cell tubes 3 are arranged in parallel, that is, the fuel cell tubes 3 are parallel to the axial direction. The fuel cell layered portions 5 are arranged and arranged in a line in the left-right direction, and the fuel cell layered portions 5 are formed in a plurality of layers in parallel in the vertical direction of the drawing.

  Further, the fuel cell layered portion 5 is sandwiched from above and below by a porous conductive plate (current collector) 9 via an outer electrode (air electrode) 7. That is, the fuel cell layered portion 5 is in a state of being laminated via the outer electrode 7 and the conductive plate-like body 9, and it is possible to take out electricity on the air electrode side from the vertical direction in the figure. .

  Here, a member composed of the fuel cell layered portion 5 (in which the fuel cell tubes 3 are arranged), the outer electrode 7 and the conductive plate-like body 9 is referred to as a fuel cell cube main body 11, and the fuel cell cube main body 11 A portion excluding the battery tube 3 is referred to as a conductive member 13.

  Furthermore, in this embodiment, as will be described in detail later, both end surfaces of the fuel cell cube body 11, that is, a pair of end surfaces from which the cylindrical fuel cell tubes 3 project are provided in the axial direction of each fuel cell tube 3. A gas seal layer 15 for preventing gas leakage is formed so as to cover other than the end portion (projecting portion having an opening) 4. That is, in the cube-shaped conductive member 13, the gas seal layer 15 is joined so as to cover both end surfaces of the fuel cell tube 3 in the axial direction.

Hereinafter, each configuration will be described in more detail.
As shown in FIG. 2, the fuel cell tube 3 includes a cylindrical inner electrode (fuel electrode) 17 in contact with a fuel gas (for example, hydrogen), and a solid electrolyte layer 19 having oxygen ion conductivity formed on the outer peripheral surface thereof. The outer electrode 7 is formed on the outer peripheral surface of the solid electrolyte layer 19 and is in contact with an oxidant gas (for example, oxygen in the air).
The number of the fuel cell tubes 3 is shown differently in each figure for easy explanation, but of course, the number is actually the same (for example, 10 vertical × 10 horizontal = 100 in total). .
The outer electrode 7 is in contact with the outer peripheral surface of another similar fuel cell tube 3 (and hence each solid electrolyte layer 19) arranged in one horizontal row in the same figure, and is shared with other fuel cell tubes 3. . That is, the outer electrode 7 is disposed between each fuel cell tube 3 and the conductive plate 9 to connect (join) each fuel cell tube 3 and the conductive plate 9.

Therefore, one fuel cell (cell) 21 is constituted by the inner electrode 17, the solid electrolyte layer 19, and the (shared) outer electrode 7.
As shown in FIG. 3, the fuel cell tube 3 is a cylinder having an outer diameter of 3 mm or less, and the cylindrical outer surface of the inner electrode 17 having a thickness of 50 to 400 μm, for example, has a thickness of 2 except for both ends. It is covered with a solid electrolyte layer 19 of ˜30 μm.

  In addition, as shown in FIG. 4, the conductive plate-like body 9 has grooves 23 having a semicircular cross-sectional shape into which the fuel cell tube 3 is fitted in parallel on both upper and lower sides. In the upper and lower conductive plate-like bodies 9 of the fuel cell cube 1, grooves 23 are formed only on one surface side.

  In particular, in this embodiment, as shown in FIG. 5, in the conductive member 13, the gas seal layer 15 is joined so as to cover both end surfaces of the fuel cell tube 3 in the axial direction. The first sealing layer 25 on the conductive member 13 side and the second sealing layer 27 laminated thereon are configured.

  The first seal layer 25 and the second seal layer 27 are glass seal layers containing a crystal phase in the glass phase, and the volume ratio of the crystal phase is different in each of the seal layers 25 and 27. Specifically, the first seal layer 25 contains, for example, glass containing Ba, Mg, Zn, Si, and Al as a main component, and contains 5 to 40% by volume of a ceramic component made of, for example, MgO as a crystal phase. . On the other hand, the second seal layer 27 contains, for example, glass containing Ba, Mg, Zn, Si, and Al as a main component, and contains 0 to 15% by volume of a ceramic component made of, for example, MgO as a crystal phase.

  That is, both the first seal layer 25 and the second seal layer 27 are glass seal layers having a structure in which ceramic particles (powder) are mixed in the glass phase, and the ceramic content contained in the first seal layer 25 is: The amount of ceramics contained in the second seal layer 27 is set higher than the content of ceramics.

  Here, when the crystal layers in the first seal layer 25 and the second seal layer 27 are of the same type, the diffusion of elements is reduced, and long-term stability is easily ensured. Further, when the first seal layer 25 includes a crystal layer that is not included in the second seal layer 27, the second seal layer easily follows the first seal layer during the heat treatment for forming the second seal layer. .

  In the fuel cell cube 1 described above, power can be generated by flowing air in the X direction of FIG. 1 and flowing fuel gas in the Y direction via the conductive plate 9. For example, the electricity collected on the inner electrode (fuel electrode) 17 side is taken out from both ends of the fuel cell tube 3, and the current collection on the outer electrode (air electrode) 7 side is taken out from the upper and lower planes of FIG. be able to.

The fuel cell cube 1 is used, for example, as a laminated cube 31 laminated in three stages, for example, as shown in FIG.
In this case, the fuel cell cube 1 is covered with the manifold 33 so as to surround the end portion 4 having the opening of the fuel cell tube 3 on both sides in the Y direction for supplying and discharging the fuel gas. That is, both end surfaces in the Y direction of the laminated cube 31 are covered with the manifolds 33 and 35. Likewise, the manifolds 37 and 39 cover both sides of the fuel cell cube 1 in the X direction for supplying and discharging air.

  When fuel gas is supplied through the pipe 41 of the fuel supply side manifold 33, the fuel gas reacts through the cylinder of the fuel cell tube 3 and is then discharged through the pipe 43 of the fuel discharge side manifold 35. Is done. Similarly, when air is supplied through the pipe 45 of the manifold 37 on the air supply side, the air reacts through the porous conductive member 13 and then exhausts through the pipe 47 of the manifold 39 on the air discharge side. Is done.

b) Next, a method for manufacturing the fuel cell cube 1 will be described.
(1) Fuel cell cube body manufacturing process For example, NiO having an average particle size of 0.1 to 2 μm (preferably 0.1 to 1 μm, more preferably 0.3 to 0.8 μm): 50% by weight, Gd _0.2 Ce _0.8 O _1.9 : 39% by weight, cellulosic binder: 7% by weight of 1 to 2 μm (preferably 0.1 to 1 μm, more preferably _{0.3 to 0.8} μm) is mixed with a dry mixer for 1 hour. Thereafter, 14% by weight of water was added to the powder and mixed for another 30 minutes.

After passing this mixture through three rolls, the prepared substrate was left overnight.
Thereafter, as shown in FIG. 7, the substrate was subjected to extrusion molding with a uniaxial hydraulic cylinder type extrusion molding machine 51.

Further, a butyral binder: 4 wt.% And methyl ethyl ketone: 100 wt.% Are added to Gd _0.2 Ce _0.8 O _{1.9 and} mixed for 24 hours to form a slurry 53. In the slurry 53, the fuel formed by the extrusion molding. The polar molded body 55 was immersed. As a result, a solid electrolyte coating 57 was formed on the surface of the fuel electrode molded body 55.

Thereafter, the fuel electrode molded body 55 on which the coating film 57 was formed was simultaneously fired in the atmosphere at 1400 ° C. for 1 hour to produce the fuel cell tube 3.
On the other hand, 93% by weight of La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ (LSCF powder) having an average particle size of 10 to 60 μm (preferably 20 to 50 μm, more preferably 30 to 50 μm) and 7% by weight of a cellulose binder are dry-treated. After mixing with a mixer for 1 hour, water was added in an amount of 14% by weight based on the powder, and the mixture was further mixed for 30 minutes.

  In addition, as a method of obtaining coarse particles such as the above LSCF powder, after calcination of the LSCF powder (about 0.1 to 2 μm), the particle size is adjusted, or the LSCF powder (0.1 to 2 μm) is used. Grade) is formed into spherical particles using a rolling granulator or spray dry, and used after calcination.

And after passing the said mixture through 3 rolls, the produced base was left overnight.
Then, the said base material was extrusion-molded with the screw-type extrusion molding machine (not shown).

Next, this molded body was fired at 1200 to 1500 ° C. for 1 to 3 hours in the air to produce a conductive plate 9. Thereby, the electroconductive plate-like body 9 with a large average particle diameter is obtained.
Thereafter, the electrode material of the outer electrode 7 was applied to the surface of the conductive plate 9 (the surface on the side of the groove 23 sandwiching the fuel cell tube 3). Specifically, with respect to LSCF powder having an average particle size of 0.1 to 2 μm (preferably 0.1 to 1 μm, more preferably 0.3 to 0.8 μm), ethyl cellulose as a binder: 5% by weight, dispersed Agent: 1 wt%, butyl carbitol: 13 wt% was added, and paste 59 mixed by three rolls was applied by screen printing so that the grooves 23 were filled.

Then, the fuel cell tube 3 was installed on the groove 23 of the conductive plate 9, and was sandwiched and laminated by another conductive plate 9.
Then, it baked at 1000 degreeC in air | atmosphere for 2 hours, and obtained the fuel cell cube main body 11 of the structure where many fuel cell tubes 3 were penetrated by the block-shaped electroconductive member 13. FIG.

(2) Gas seal layer forming step Glass powder composed of Ba, Mg, Zn, Si, Al having a softening point of 700 ° C. and an average particle size of 4 μm, and a particle size of a predetermined amount (for example, 20% by volume with respect to glass) Appropriate amounts of polyvinyl butyral, amine-based dispersant, and plasticizer were added to magnesia powder with an average of 2 μm, and a slurry was obtained using ethanol and toluene as solvents.

  Using the obtained slurry, a sheet was formed by a doctor blade method and cut to obtain a glass sheet 61 having a thickness of 300 μm as shown in FIG. A large number of through-holes 63 into which the fuel cell tubes 3 are inserted are formed in the glass sheet 61 by punching.

  Separately, an appropriate amount of ethyl cellulose and an amine-based dispersant was added to the glass powder and a predetermined amount (for example, 5% by volume of glass) of the magnesia powder, and a paste was prepared using butyl carbitol as a solvent. .

This paste was applied to one surface of the glass sheet 61 to form a paste layer 65.
Then, the glass sheet 61 having the paste layer 65 is placed on the conductive member 13 side, the fuel cell tube 3 is passed through the through hole 63, and the end surface of the fuel cell cube body 11 (that is, the end surface of the conductive member 13). Joined. The glass sheet 61 was adhered to both end faces of the fuel cell cube body 11 by the adhesive force of the paste layer 65.

  The glass that has flowed out from the gap between the gas seal layer 15 and the fuel cell tube 3 when the glass sheet 61 having the paste layer 65 is bonded to the base portion of each fuel cell tube 3 protruding from the gas seal layer 15. Ingredients and the like are attached to the belt.

  Thereafter, the fuel cell cube body 11 was heated at a temperature higher than the softening point of glass, for example, 700 ° C. for 2 hours to soften the paste layer 65, and the glass sheet 61 was firmly bonded to the fuel cell cube body 11.

Since the glass sheet 61 contains more ceramics than the paste layer 65, even when the paste layer 65 is softened, its shape is hardly collapsed.
As a result, the fuel cell cube 1 in which the gas seal layer 15 is joined to the end face of the fuel cell cube body 11 is obtained.

c) As described above, the fuel cell cube 1 of the present embodiment has a glass sheet (low ceramic content) on the end surface of the fuel cell cube body 11 via the paste layer 65 (high ceramic content). Since 61 is brought into close contact with each other and heated and joined, even with a complicated structure in which a large number of fuel cell tubes 3 protrude from the end face of the fuel cell cube body 11, high airtightness can be realized. That is, since the gas seal layer 15 is in close contact with the fuel cell tube 3 without a gap, the conductive member 13 side (inner side) and the opposite side (outer side: the fuel cell tube 3 protrudes across the gas seal layer 15. Gas does not leak between the two sides.
Accordingly, as shown in FIG. 6, when supplying fuel gas to the fuel cell cube 1 with the fuel supply side and the discharge side covered with the manifolds 33 and 35, the end 4 of the fuel cell tube 3 is used. In this embodiment, since the gas seal layer 15 is in close contact with the fuel cell tube 3 without any gap, gas leaks between the inside of the conductive member 13 and the outside thereof. There is nothing to do. Therefore, it becomes a very efficient device.

(Experimental example 1)
Next, an experimental example for confirming the effect of the present invention will be described.
In this experimental example, a sample having a configuration substantially similar to that of the above-described embodiment was produced, and the gas sealing property was examined.

<Preparation of sample>
-The glass sheet of the various composition of following Table 1 was produced similarly to the said embodiment.
-The glass paste of the various composition of following Table 1 was produced like the said embodiment.

-The porous body for a test was produced with the following method.
La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ (LSCF powder) was mixed with 100% by weight of polymethyl methacrylate beads, and 7% by weight of a cellulose binder was further added to the LSCF powder with a dry mixer. After time mixing, water was added in an amount of 14% by weight based on the powder, and the mixture was further mixed for 30 minutes. The thus-prepared soil is allowed to stand overnight, and then the soil is extruded into a flat plate shape with a screw-type extruder and cut into squares. The test body was fired for a time to obtain a test porous body.

<Confirmation method of shrinkage rate during heat treatment of glass sheet>
The glass sheet was cut into 1 cm square (thickness: 50 to 500 μm), and the glass paste was applied to the entire surface of one side by screen printing so as to have a thickness of 200 μm. After leaving for about 3 minutes, the glass paste applied to the glass sheet was attached as an adhesive to the surface of a 2 cm square test porous body and subjected to heat treatment at 700 ° C. for 2 hours. And the dimension of the glass sheet before and after heat processing was measured, it calculated how much it shrunk before and after heat processing, and the shrinkage | contraction rate (length direction) was calculated | required. The results are shown in Tables 1 and 2 below.

<Method for confirming gas sealability>
Using the sample used for the measurement of the shrinkage rate, the gas sealing property was confirmed using the measuring instrument 71 shown in FIG.

  In this measuring instrument 71, a sample 81 (with a glass seal 79 attached to the surface of the test porous body 57) is sandwiched between the upper and lower annular packings 73, 75 with the glass seal 79 facing upward, The tool 83 is tightened and sealed with a screw (not shown), and gas (for example, air) is supplied from the gas cylinder 85 to the central flow path 87 of the measuring instrument 71.

  Specifically, in a state where a gas pressure of 0.2 MPa is applied from one side (upper side) of the sample 81, the gas supply valve 89 is closed, and the applied gas pressure is 10 hours after the gas supply valve 89 is closed. The degree of decrease was confirmed by the gas pressure gauge 91. The results are shown in Table 1 below.

この表１及び表２から明らかな様に、実施例の試料No.１〜１５は、ガラスシートに混合されているＭｇＯの添加量が、ガラスペーストに混合されているＭｇＯの添加量より少ないので、ガラスシートの熱収縮率が２％以下であり、１０時間後のガラスリーク量が５％以下と少なく好適である。

As is apparent from Table 1 and Table 2, sample Nos. 1 to 15 in the examples have a smaller amount of MgO added to the glass sheet than the amount of MgO added to the glass paste. The glass sheet has a heat shrinkage rate of 2% or less, and the glass leak amount after 10 hours is as small as 5% or less.

Further, from Table 1 and Table 2, it can be seen that the shrinkage of the glass sheet increases as the amount of MgO added to the glass sheet increases. Furthermore, it can be seen that as the amount of MgO added to the glass paste increases, the amount of shrinkage of the glass sheet during heat treatment decreases. As for the gas leak rate, it can be seen that as the amount of MgO added to the glass sheet and glass paste increases, the gas leak increases.
Moreover, when Example No. 2 and 13-15 are compared, although the thickness of the 2nd seal layer is changed, while the sheet thickness becomes thin, the followability to the 1st seal layer of the 2nd seal layer It can be seen that the shrinkage rate of the glass sheet is reduced.

In addition, it is considered that the sample Nos. 1, 3, 6, and 12 of the comparative example had a high gas leak rate because the amount of MgO added to the glass paste was too large. In Comparative Samples Nos. 8 to 12, it is considered that the gas leak rate was increased because the amount of MgO added to the glass sheet was too large. Comparative Sample Nos. 2, 4, 5, 7, and 8 had a smaller amount of MgO added to the glass paste than the amount of MgO added to the glass sheet, and as a result, the amount of shrinkage of the glass sheet increased. Conceivable.
In Comparative Example No. 13, the glass sheet was as thin as 15 μm, and it was difficult to handle the sheet, so a sample could not be prepared. In Comparative Example No. 14, the sheet is as thick as 600 μm, the followability of the second seal layer to the first seal layer is poor, and the shrinkage rate of the glass sheet is considered to be large.

In addition, this invention is not limited to the said embodiment etc. at all, and it cannot be overemphasized that it can implement with a various aspect in the range which does not deviate from this invention.
For example, in the said embodiment, although the glass sheet produced by the doctor blade method was used, it replaced with this glass sheet and may use the temporary baking body of a glass sheet.

  In the case of using this temporarily fired body, the amount of shrinkage due to the temporarily firing process is calculated at the stage of the punching process, punched according to the tube piping of the fuel cell cube, and temporarily fired at 650 ° C. for 1 hour. Can be obtained. The heat treatment temperature here is desirably fired at a temperature lower than 50 to 100 ° C. with respect to the main firing temperature.

It is a perspective view which shows a solid oxide fuel cell cube. It is sectional drawing which expands and shows a part of AA cross section of FIG. It is a perspective view which shows the fuel cell tube used for a solid oxide fuel cell cube. It is a perspective view which shows the electroconductive plate-shaped body used for a solid oxide fuel cell cube. It is explanatory drawing which expands and shows the gas-seal part of a solid oxide fuel cell cube. It is explanatory drawing which decomposes | disassembles and shows the apparatus with which the some solid oxide fuel cell cube was combined. It is explanatory drawing which shows the manufacturing method of a solid oxide fuel cell cube. It is explanatory drawing which shows the formation method of the gas seal part of a solid oxide fuel cell cube. It is explanatory drawing which shows the experimental method of an experiment example.

Explanation of symbols

1. Solid oxide fuel cell stack (fuel cell cube)
3 ... Fuel cell tube 5 ... Fuel cell layered part 7 ... Air electrode (outer electrode)
DESCRIPTION OF SYMBOLS 9 ... Conductive plate-like body 11 ... Fuel cell cube main body 13 ... Conductive member 15 ... Gas seal layer 17 ... Fuel electrode (inner electrode)
DESCRIPTION OF SYMBOLS 19 ... Solid electrolyte layer 21 ... Fuel cell 25 ... 1st sealing layer 27 ... 2nd sealing layer

Claims (13)

In a solid oxide fuel cell comprising: a fuel cell constituent member constituting a solid oxide fuel cell; and a gas seal layer bonded to the fuel cell constituent member to seal a gas.
The gas seal layer is composed of a plurality of seal layers mainly composed of glass, and at least one of the plurality of seal layers is a seal layer containing a crystal phase in a glass phase,
The plurality of seal layers include a first seal layer in contact with the fuel cell component and a second seal layer formed on a surface of the first seal layer, and a volume of a crystal phase in the first seal layer. The solid oxide fuel cell, wherein the ratio is larger than the volume ratio of the crystal phase in the second seal layer.   2. The solid oxide fuel cell according to claim 1, wherein the second seal layer has a thickness of 20 to 500 μm.   3. The solid oxide fuel cell according to claim 1, wherein the constituent elements of the glass phase in the first seal layer and the second seal layer are the same.   The volume ratio of the crystal phase of the first seal layer and the second seal layer is different depending on the difference in the amount of at least one filler mixed in each of the seal layers. The solid oxide fuel cell according to any one of the above.   5. The solid oxide fuel cell according to claim 4, wherein the amount of filler added to the first seal layer is 5 to 40% by volume.   The solid oxide fuel cell according to claim 4 or 5, wherein the amount of filler added to the second seal layer is 0 to 15% by volume.   The solid oxide fuel cell according to any one of claims 1 to 6, wherein a softening point of the glass is 500 ° C or higher.   The said filler is an oxide containing at least 1 sort (s) among the elements of Al, Mg, Zr, Ce, and Si, or a mixture of these oxides. Solid oxide fuel cell. A method for producing a solid oxide fuel cell according to any one of claims 1 to 8,
The first seal layer forming paste and the second seal layer forming sheet are prepared, and the sheet is brought into close contact with the surface of the fuel cell constituent member through the paste, and then heat treated and bonded. A method for producing a solid oxide fuel cell.   10. The solid oxide according to claim 9, wherein the first seal layer forming paste and the second seal layer forming sheet are prepared using a material obtained by mixing the glass material with a filler. Of manufacturing a fuel cell.   11. The method for producing a solid oxide fuel cell according to claim 10, wherein the sheet for forming the second seal layer is produced by a doctor blade method.   The paste is applied to the surface of the sheet or the pre-fired body of the sheet, the sheet or the pre-fired body is closely adhered to the fuel cell constituent member by the paste, and heat-treated at a temperature at which the glass is softened, The method for producing a solid oxide fuel cell according to any one of claims 9 to 11, wherein a sheet or a temporarily fired body thereof is joined to a surface of the fuel cell constituent member. The sheet or its pre-fired body has a through-hole through which a fuel cell tube having a cylindrical inner electrode and a solid electrolyte layer formed on the outer peripheral surface thereof penetrates,
13. The solid oxide fuel cell according to claim 12, wherein the fuel cell tube is passed through the through hole, and the sheet or a temporarily fired body thereof is joined to a surface of the fuel cell constituent member by the heat treatment. Manufacturing method.

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