JP5320949B2 - Single-chamber solid oxide fuel cell and its stack structure - Google Patents

Description

  The present invention relates to a single-chamber solid oxide fuel cell and a stack structure thereof.

  Conventionally, flat plate type, cylindrical type, etc. have been proposed as cell designs for solid oxide fuel cells. A flat cell is one in which a fuel electrode and an air electrode are respectively arranged on the front and back surfaces of a plate-like electrolyte, and a plurality of cells formed in this way are used in a state where they are stacked via separators. The separator plays the role of separating the fuel gas and the oxidant gas supplied to each cell. Further, a gas seal is provided between each cell and the separator (for example, Patent Document 1).

On the other hand, a cylindrical cell has a fuel electrode and an air electrode arranged on the outer peripheral surface and inner peripheral surface of a cylindrical electrolyte, and a cylindrical vertical stripe type, a cylindrical horizontal stripe type, and the like have been proposed (for example, Patent Documents). 2).
JP-A-5-3045 (first page, FIG. 6) Japanese Patent Laid-Open No. 5-94830 (first page, FIG. 1)

  As described above, in the flat and cylindrical solid oxide fuel cells, a high output can be obtained by stacking a plurality of cells. However, as a single cell, a large reaction area of the electrode is taken. However, in order to increase the output, the number of cell stages in the stack increases, resulting in a large-capacity stack, and the cost increases due to an increase in the number of single cells. In addition, since the single chamber type can generate power with a mixed gas of fuel gas and oxidant gas, the flat type does not require a necessary seal and has an advantage of simplifying the stack structure. However, since power generation is performed in a situation where the fuel gas is diluted rather than the so-called two-chamber type in which the fuel gas and the oxidant gas are separated, there is a problem of low output. However, there was a problem that there were more than the two-chamber type.

  From the above situation, in the case of stacking, there has been a demand for a solid oxide fuel cell capable of reducing the number of cell stages and miniaturizing but capable of increasing output.

  The present invention has been made to solve the above-described problem. Even in a single-chamber type, the solid oxide fuel cell can suppress the number of cell stages when stacked and can be made high in size while being small. And a stack structure thereof.

  The solid oxide fuel cell according to the present invention is made to solve the above-described problem, and is formed with at least one first through hole and at least one second through hole extending in the same axial direction. The first and second through-holes are formed on both ends of the electrolyte, the fuel electrode formed on the inner wall surface of the first through-hole, and the inner wall surface of the second through-hole. An air electrode, wherein the first and second through holes are arranged adjacent to each other, arranged so as not to contact the fuel electrode and the air electrode, and generate electricity with a mixed gas of fuel gas and oxidant gas. .

  According to this configuration, a plurality of through holes are formed in the electrolyte, and the fuel electrode and the air electrode are formed on the inner wall surfaces of these through holes, respectively. And the 1st through-hole in which the fuel electrode was formed, and the 2nd through-hole in which the air electrode was formed are made to adjoin. Therefore, if a mixed gas of fuel gas and oxidant gas is supplied to each through hole, power generation is performed by the electrolyte that forms the fuel electrode, the air electrode, and the partition wall therebetween. As described above, since a plurality of through holes are formed in the electrolyte, and the fuel electrode and the air electrode are formed therein, the reaction area of the electrode can be reduced by reducing the number of through holes and increasing the number of through holes. Becomes a high-power single cell and can be reduced in size when stacked.

  In the present invention, various electrolyte and through-hole structures can be selected. The cross-sectional shape of the through hole is not particularly limited, and various shapes such as a circle, an ellipse, and a polygon are possible. Moreover, the through-hole does not necessarily have to extend linearly, as long as gas can be circulated. Furthermore, the cross-section of each through-hole can be formed in a polygonal shape so as to have a honeycomb structure as a whole. Thereby, the rigidity of a battery improves and impact resistance performance improves.

  In the battery, the electrolyte may be gas impermeable or may be formed of a porous material that allows gas to pass therethrough. When formed of a porous material, the opening of the first through hole at one end of the electrolyte can be closed, and the opening of the second through hole at the other end of the electrolyte can be closed. According to this configuration, the following effects can be obtained. That is, since it is the second through hole that opens at one end portion of the electrolyte, when the mixed gas of the fuel gas and the oxidant gas is supplied to the second through hole, the mixed gas first becomes the air electrode. Reacts with Thereby, oxygen is mainly consumed in the mixed gas, so that the gas in the second through hole is rich in fuel gas. Thereafter, the mixed gas passes through an electrolyte made of a porous material, that is, a partition wall between the first and second through holes, and flows into the first through hole. In the first through hole, the mixed gas rich in fuel gas comes into contact with the fuel electrode, and is then discharged from the other end of the electrolyte to the outside. Therefore, although it is a single chamber type battery, the supply efficiency of the fuel gas to a fuel electrode becomes high, and it can achieve high output.

  The fuel cell can be configured as follows. That is, the fuel electrode extends from the inner wall surface of the first through hole to be formed on the end surface of the other end of the electrolyte, and the air electrode extends from the inner wall surface of the second through hole to the end surface of the one end of the electrolyte. Form. According to this configuration, when stacking the fuel cells, the fuel electrode and the air electrode are brought into contact simply by bringing one end and the other end of the plurality of fuel cells into contact with each other. be able to.

  Alternatively, the first current collector connected to the fuel electrode and extending from the inner wall surface of the first through hole and formed on the end surface of the other end of the electrolyte, and the inner wall surface of the second through hole connected to the air electrode And a second current collector formed on the end face of one end of the electrolyte. With this configuration, in the same manner as described above, when stacking fuel cells, the fuel electrode and the air electrode are brought into contact only by bringing one end and the other end of the plurality of fuel cells into contact with each other. Such a current collector can be formed of, for example, a material containing Ag.

  The stack structure of the solid oxide fuel cell according to the present invention includes the above-described plurality of solid oxide fuel cells, and the plurality of solid oxide fuel cells includes one end and the other end. Are arranged side by side in the axial direction, and the fuel electrode and the air electrode of the adjacent solid oxide fuel cell are electrically connected at one end and the other end.

  In the case of stacking, at least one third current collector can be further provided, and the fuel electrode and the air electrode of the adjacent solid oxide fuel cell are electrically connected via the third current collector. Can be connected to. In this case, various current collectors can be used, but it is necessary to prevent the gas from flowing between adjacent batteries. For example, the current collector can be formed only at a part of the end portion of the electrolyte, or can have a predetermined pattern. Alternatively, the current collector can be formed in a mesh shape.

  According to the present invention, even in a single-chamber type, the number of cell stages in the stack is suppressed, and high output can be achieved while being small.

(First embodiment)
A first embodiment of a solid oxide fuel cell according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a solid oxide fuel cell according to this embodiment.

  As shown in FIG. 1, the solid oxide fuel cell according to the present embodiment includes an electrolyte 1 formed in a rectangular parallelepiped shape. The electrolyte 1 penetrates through an upper end portion 11 and a lower end portion 12. Two through holes 13 and 14 are formed. The four through-holes 13 and 14 have a rectangular cross section and are aligned in a lattice shape. Here, the four through-holes are divided into two, the right back and left front through-holes in FIG. 1 are referred to as first through holes 13, and the left back and right front through-holes in FIG. 1 are referred to as second through holes 14. I will do it.

  2 is a cross-sectional view taken along line AA of FIG. 1 (a), a plan view (b) seen from the upper end of FIG. 1, a plan view (c) seen from the lower end of FIG. 1, and FIG. It is BB sectional drawing of (a). As shown in FIGS. 2 and 3, the fuel electrode 2 is applied to the inner wall surface of each first through hole 13. On the other hand, the air electrode 3 is applied to the inner wall surface of each second through hole 14. As shown in FIG. 2 (b), the fuel electrode 2 extending from the inner wall surface of the first through hole 13 is applied to almost the entire end surface of the upper end portion 11 of the electrolyte 1. On the other hand, as shown in FIG. 2C, the air electrode 3 extending from the second through hole 14 is applied to almost the entire surface of the end surface of the lower end portion 12 of the electrolyte 1. Here, the fuel electrode 2 and the air electrode 3 are applied so as not to contact each other. That is, as shown in FIG. 3, the fuel electrode 2 in the first through-hole 13 does not extend to the lower end portion 12 of the electrolyte 1 but terminates in front of it. Similarly, the air electrode 3 terminates before the upper end portion 11 of the electrolyte 1. Thus, a gap 15 is formed between the fuel electrode 2 and the air electrode 3.

  Subsequently, 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, etc. Oxygen ion conductive ceramic materials such as oxides, zirconia-based oxides containing scandium and yttrium can be used. Further, the electrolyte 1 can be formed of either a dense material or a porous material.

  The electrolyte 1, the fuel electrode 2, and the air electrode 3 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 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 may be a powder modification to nickel or a nickel modification to ceramic material. Good. Moreover, the ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types. The fuel electrode 2 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) CoO3, (La, Sr) MnO3, (La, Sr) CoO3, (La, Sr) (Fe, Co) O3, (La, Sr) (Fe, Co, Ni) O3 (La, Sr) (Fe, Co) O3 is preferable. The ceramic material mentioned above can be used individually by 1 type or in mixture of 2 or more types.

  The fuel electrode 2 and the air electrode 3 can be formed by, for example, a wet coating method. Examples of the wet coating method include a dip coating method. At this time, the fuel electrode 2 and the air electrode 3 need to be paste-like, and are formed by adding the 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.

  Next, an example of a manufacturing method of the solid oxide fuel cell configured as described above will be described. Here, a method for forming an electrode by a dip coating method will be described.

  First, the electrolyte powder material is kneaded with a binder, extruded to form four through holes 13 and 14, and sintered under known conditions to prepare a rectangular parallelepiped electrolyte 1. Subsequently, containers each containing a fuel electrode paste and an air electrode paste are prepared. And after masking the area | region which should form the air electrode 3 in the electrolyte 1, the electrolyte 1 is immersed in a container and a fuel electrode paste is apply | coated to the electrolyte surface. Thereafter, the fuel electrode 2 is formed by drying and sintering at a predetermined temperature for a predetermined time. Next, after masking the region where the fuel electrode 2 is formed in the electrolyte 1 and the region where the gap 15 is to be formed, the electrolyte 1 is submerged in a container, and an air electrode paste is applied to the electrolyte surface. Thereafter, the air electrode 3 is formed by drying and sintering at a predetermined temperature for a predetermined time. Thus, the fuel cell is completed.

The fuel cell configured as described above generates power as follows. First, as shown in FIG. 3, a mixed gas G of a fuel gas made of hydrocarbons such as hydrogen or methane or ethane and an oxidant gas such as air is passed from the upper surface of the electrolyte 1 to the through holes 13 and 14. Supply. Thereby, the mixed gas G supplied to the first through hole 13 contacts the fuel electrode 2, and the mixed gas supplied to the second through hole 14 contacts the air electrode 3. At this time, each of the fuel electrode 2 and air electrode 3, order to selectively react with the fuel gas and oxidant gas in the mixed gas G, with the fuel electrode 2 and air electrode 3, through electrolyte 1 Oxygen ion conduction occurs and power is generated.

  As described above, according to the present embodiment, the plurality of through holes 13 and 14 are formed in the electrolyte 1, and the fuel electrode 2 and the air electrode 3 are formed on the inner wall surfaces of the through holes 13 and 14, respectively. Therefore, a plurality of fuel electrodes 2 and air electrodes 3 can be formed with respect to one electrolyte 1, and by reducing the number of through holes and increasing the number of through holes, the reaction area of the electrodes is increased, resulting in high output. It becomes a simple single cell and can be reduced in size when stacked.

By the way, if a plurality of batteries configured as described above are prepared, stacking becomes possible. In the fuel cell, the fuel electrode 2 and the air electrode 3 are applied to the end surfaces of the upper end portion 11 and the lower end portion 12, respectively. Therefore, when a plurality of batteries are prepared and arranged in the axial direction so that the upper end portion 11 and the lower end portion 12 face each other, the fuel electrode 2 and the air electrode 3 are in contact with each other, so that the plurality of batteries are simply connected in series. can do. Alternatively, as shown in FIG. 4, the current collector 4 can be disposed between adjacent batteries. In the example of this figure, a mesh-like current collector 4 is arranged. By carrying out like this, mixed gas can be distribute | circulated between adjacent batteries. The material constituting the current collector 4 is specified by, for example, conductive metal materials such as Pt, Au, Ag, Ni, Cu, and stainless steel materials, or La (Cr, Mg) O ₃ , (La, Ca) CrO. ₃ , (La, Sr) CrO ₃ and other conductive metal oxide materials such as lanthanum chromite, such as Ag, use a material that melts at a lower temperature than the electrolyte and electrode In such a case, each single cell may be superimposed on the current collector and then integrated by sintering. One of these may be used alone, or two or more may be mixed and used.

(Second Embodiment)
Next, a second embodiment of the solid oxide fuel cell according to the present invention will be described. This embodiment is different from the fuel cell of the first embodiment in that a lid member is attached to the electrolyte material and some openings of the through holes, and the other configurations are the same. The description is abbreviate | omitted and attached | subjected. Hereinafter, this fuel cell will be described with reference to FIGS. FIG. 5 is a plan view (a) of the fuel cell viewed from the upper end and a plan view (b) of the fuel cell viewed from the lower end, and FIG. 6 is a cross-sectional view taken along the line CC in FIG.

  As shown in FIGS. 5 and 6, in this fuel cell, the lid member 5 is attached to the opening of the first through hole 13 at the upper end of the electrolyte 1 and closed. Further, the lid member 5 is attached to the opening of the second through hole 14 at the lower end of the electrolyte 1 to close it. These lid members 5 are formed of a gas-impermeable material, and can be formed of, for example, a glass-based material or a ceramic-based material containing silica, alumina, or the like. Further, the electrolyte 1 used in this embodiment is formed of a porous material so that gas can permeate therethrough.

The fuel cell configured as described above generates power as follows. First, as shown in FIG. 6, similarly to the first embodiment, a mixed gas G of a fuel gas and an oxidant gas is supplied from the upper end portion of the electrolyte 1 to the second through hole 14. Thereby, the mixed gas first comes into contact with the air electrode 3, and oxygen in the mixed gas G is consumed. For this reason, the gas in the second through hole 14 is rich in fuel gas. Thereafter, the mixed gas G passes through the partition wall between the electrolyte 1, that is, the first and second through holes 13 and 14, and flows into the first through hole 13. In the first through hole 13, the mixed gas G rich in fuel gas contacts the fuel electrode 2. Thereafter, the mixed gas G is discharged from the lower end 12 of the electrolyte 1 to the outside through the first through hole 13. In the above process, because the fuel gas and oxidant gas in the mixed gas G and the electrodes 2 and 3 are reacted selectively, between the fuel electrode 2 and air electrode 3, through electrolyte 1 oxygen Ion conduction occurs and power is generated.

  As described above, according to the present embodiment, according to this configuration, the electrolyte 1 is formed of a porous material, the mixed gas G is first reacted with the air electrode in the second through hole, and then the first It is comprised so that it may flow in into the through-hole. Therefore, the mixed gas G flowing into the first through hole 13 is rich in fuel gas. Therefore, although it is a single chamber type battery, the supply efficiency of the fuel gas to the fuel electrode 2 becomes high, and high output can be achieved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these, A various change is possible unless it deviates from the meaning of this invention.

  In each of the above embodiments, the fuel electrode 2 and the air electrode 3 are formed so as to extend to the opening periphery of the through hole, but a current collector may be provided on the opening periphery of the through hole. For example, as shown in FIG. 7, a current collector can be provided on the periphery of the opening of the fuel cell shown in the first embodiment. In this example, the first current collector 6 is formed so as to cover the fuel electrode 2 at the opening periphery of the upper end of the first through hole 13. Further, a second current collector 7 is formed at the opening periphery of the lower end of the second through hole 14 so as to cover the air electrode 3. Furthermore, it can also be as shown in FIG. In this example, the fuel electrode 2 and the air electrode 3 are formed only inside the through holes 13 and 14. And the 1st electrical power collector 6 extended from the upper end part of the fuel electrode 2 to the opening periphery of the upper end of the 1st through-hole 13 is formed. Similarly, a second current collector 7 extending from the lower end of the air electrode 3 to the opening periphery of the lower end of the second through hole 14 is formed. Even when such current collectors 6 and 7 are provided, stacking is facilitated and the current collection efficiency is improved. Moreover, the material which comprises these electrical power collectors 6 and 7 can be made into the material of the electrical power collector mentioned above besides Ag.

  Moreover, in each said embodiment, although the four cross-sectional rectangular through-holes are formed in the electrolyte 1, it is not limited to this, The number and shape of a through-hole are not specifically limited. For example, if the through-hole is formed in a polygonal shape and has a honeycomb structure as a whole, the rigidity of the battery is improved and the impact resistance is improved.

1 is a perspective view showing a first embodiment of a solid oxide fuel cell according to the present invention. It is the sectional view on the AA line of FIG. 1 (a), the top view (b) seen from the upper end of FIG. 1, and the top view (c) seen from the lower end of FIG. It is the BB sectional view taken on the line of Fig.2 (a). It is a perspective view which shows the stack structure of the solid oxide fuel cell of FIG. It is the top view (a) which looked at the fuel cell which concerns on 2nd Embodiment of this invention from the upper end, and the top view (b) seen from the lower end. It is CC sectional view taken on the line of Fig.5 (a). FIG. 3 is a cross-sectional view showing another example of the solid oxide fuel cell shown in FIG. 1. FIG. 3 is a cross-sectional view showing another example of the solid oxide fuel cell shown in FIG. 1.

Explanation of symbols

1 Electrolyte 11 Upper end (one end)
12 Lower end (other end)
13 First through hole 14 Second through hole 2 Fuel electrode 3 Air electrode 4 Current collector (third current collector)
5 Lid member 6 First current collector 7 Second current collector

Claims (8)

At least one first through-hole and at least one second through-hole extending in the same axial direction are formed, and the first and second through-holes are formed by a porous material that opens at both ends . Electrolyte,
A fuel electrode formed on the inner wall surface of the first through hole;
An air electrode formed on the inner wall surface of the second through hole,
The first and second through holes are disposed adjacent to each other;
Arranged so that the fuel electrode and the air electrode do not contact,
A single-chamber solid oxide fuel cell that generates electricity using a mixture of fuel gas and oxidant gas. An opening is closed in the first through-hole at one end portion of the electrolyte, the opening of the second through-hole in the other end portion of the electrolyte is closed, solid oxide according to claim 1 Fuel cell. The fuel electrode extends from an inner wall surface of the first through hole and is formed on an end surface of the other end of the electrolyte.
3. The solid oxide fuel cell according to claim 1, wherein the air electrode extends from an inner wall surface of the second through hole and is formed on an end surface of one end of the electrolyte. A first current collector connected to the fuel electrode and extending from an inner wall surface of the first through hole and formed on an end surface of the other end of the electrolyte;
A second current collector connected to the air electrode and extending from an inner wall surface of the second through hole and formed on an end surface of one end of the electrolyte;
Further comprising in that, the solid oxide fuel cell according to claim 1 or 2. The solid oxide fuel cell according to claim 4 , wherein the first and second current collectors contain Ag. A plurality of solid oxide fuel cells according to any one of claims 1 to 5 ,
The plurality of solid oxide fuel cells are arranged side by side in the axial direction so that the one end and the other end face each other,
A stack structure of a solid oxide fuel cell, wherein a fuel electrode and an air electrode of the adjacent solid oxide fuel cell are electrically connected to each other at the one end and the other end. And further comprising at least one third current collector,
The stack structure of the solid oxide fuel cell according to claim 6 , wherein a fuel electrode and an air electrode of the adjacent solid oxide fuel cell are electrically connected via the third current collector. . The stack structure of a solid oxide fuel cell according to claim 7 , wherein the third current collector is formed in a mesh shape.

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