JPH02168568A - Fuel battery with solid electrolyte - Google Patents

Abstract

PURPOSE:To provide a fuel battery free from risk of heat damage by introducing reaction gas to guide vanes of a reaction gas supplying device, allowing it to flow from the central part to the perimeter, thereby decreasing necessity for use of gas seal, and by using a glass seal at cell tack of the gas supplying device and unitary cell. CONSTITUTION:A space is bounded by the inner surface of a unitary cell, a reaction gas supplying device, and reaction gas lead-in pipes 4, 5, while another space is formed limited by the outside surface of the unitary cell and the reaction gas supplying device, and therein a glass seal 6 is provided either in the former space or in both. Thereby the reaction gas is introduces to guide vanes 19A, 19B of reaction gas supplying devices 7, 11 and flows from the central part to the perimeter. This decreases necessity for use of a gas seal between the unitary cell and the supplying devices 7, 11. Also the gas seals minimally needed at the central part or perimeters of the cell tack of the unitary cell and supplying devices 7, 11 consist of a glass seal, so that component members of the battery can make thermal expansion and contraction freely.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cell structure of a solid oxide fuel cell, and particularly to a fuel cell that is free from thermal damage.

[Conventional technology]

Fuel cells using oxide solid electrolytes such as zirconia are
Because its operating temperature is as high as 800-1100℃,
It has high power generation efficiency, does not require a catalyst, and is easy to handle because the electrolyte is solid, so it is expected to be used as a third-generation fuel cell.

However, solid oxide fuel cells are prone to thermal damage because their main constituent material is ceramics.
Furthermore, it has been difficult to realize this because there is no appropriate gas sealing method. Therefore, a cylindrical fuel cell with a special shape was devised, which solved the above two problems and successfully conducted battery operation tests, but the power generation density per unit volume of the battery was low and it was not economically viable. There is no prospect of anything favorable yet.

In order to increase the power generation density, it is necessary to use a flat plate type. For example, a type of flat plate fuel cell having a structure shown in an exploded perspective view of FIG. 6 is known.

In this type of fuel cell, single cells 17 (consisting of a solid electrolyte plate 17A and electrodes 17B and 17C) and separate plates 18 are alternately stacked, and grooves of the separate plates that intersect at right angles in a three-dimensional manner contain different reactions. Gas is flushed.

[Problem to be solved by the invention]

Reactant gases are separately introduced into the fuel cell using a gas manifold (not shown). At this time, in order to separate and sufficiently supply the reaction gas into the fuel cell, it is necessary to provide a gas seal between the unit cell 17 and the separate plate 18.

Single cell 17 and separate plate 18 for gas sealing
It is possible to sinter the two together, but in this method,
Since the single cell and the separate plate are made of different materials,
Cracks occur in the monolithic sintered body due to slight differences in thermal expansion coefficients or non-uniformity in temperature distribution. It is also conceivable to form a single cell and a separate plate separately and laminate them with a sealing material in between, but in this case there is no suitable gas sealing material for high temperatures.

The present invention has been made in view of the above points, and its purpose is to create a solid oxide fuel cell that is free from thermal damage due to temperature changes and has excellent reliability by using a fuel cell structure that eliminates the need for gas seals as much as possible. I am excited to provide this.

[Means to solve the problem]

According to the present invention, the above object is to provide a single cell in which a porous anode and a cathode are arranged on both main surfaces of a solid electrolyte body, and to separately supply both reactant gases, a fuel gas and an oxidizing gas, to the single cell. and a reactant gas supply means for electrically connecting with the single cell.In a solid oxide fuel cell, a guide layer 19A guides the reactant gas from the center of the main surface of the ill toward the periphery. , 19B, and (2) a reactant gas supply means 7゜11 having a laminate of the single cell and the reactant gas supply means, which penetrates in the stacking direction through the center of the stack, and supplies the reactant gas from the gas hole on the side surface to the guide layer. a glass seal 6 disposed in at least the former of the reaction gas introduction pipes 4 and 5 to be diffused; the space formed by the introduction pipes; the space formed by the outer peripheral surface of the unit 3 and the reaction gas supply means; This is achieved by having the following.

The reaction gas supply means includes a porous first substrate that supports a single cell, a porous or dense second substrate that supports an interconnector layer that is dense and prevents mixing of reaction gases, and a dense separate substrate. Includes boards etc. The glass seal provided on the outer peripheral surface of the single cell works effectively when the reaction gas supply means is dense, and the glass material is soda lime glass,
Alumina silicate glass 1 lithium silicate glass, barium borosilicate glass 1 borosilicate glass, etc. can be used.

[Effect]

Since the reaction gas is guided to the guide layer of the reaction gas supply means and flows from the center to the periphery, the need for a gas seal between the unit cell and the reaction gas supply means is reduced. The glass seal softens or melts at the operating temperature of the fuel cell, providing a sealing function.

〔Example〕

(Example 1) Next, an example of the present invention will be described based on the drawings. 1st
The figure is a vertical cross-sectional view of a solid oxide fuel cell according to an embodiment of the present invention, showing an anode 1, a solid electrolyte body 3, and a cathode 2.
A porous substrate 7 (first substrate) with rib-shaped guide wings 19B, which is a reaction gas supply means, in which a single cell is formed, and a porous substrate with lip-shaped guide wings 19A, which is a reaction gas supply means, in which an ink connector layer 12 is formed. The quality substrate 11 <second substrate) is
They are stacked alternately, and a fuel gas introduction pipe 4 is installed in the center of the stack.
(reactive gas introduction pipe) and oxidant gas introduction pipe 5 (reactive gas introduction pipe) are arranged to constitute a fuel cell.

Such a battery is prepared as follows.

The porous substrate 7 with rib-like guide wings having a thickness of 2u is made of NiZr0□
It is formed using Therme 7). NiZr(h cermet) is plasma sprayed onto the flat main surface of the porous substrate 7 with lip-shaped guide wings to form a porous anode 1 with a thickness of 100μ. Plasma spraying is performed to form a dense solid electrolyte body 3 with a thickness of 30μ.Next, lanthanum strontium manganese oxide La (SMn03) is plasma sprayed,
A porous cathode 2 having a thickness of 800 Jrm is formed.

On the other hand, the porous substrate 11 with rib-like guide wings having a thickness of 2
It is formed using (Sr)MnOz. Lanthanum chromite LaCrO3 is plasma sprayed onto the flat main surface of this porous substrate 11 with lip-shaped guide wings to form a dense interconnector layer 12 with a thickness of 40 nm. Lanthanum chromite has electronic conductivity and is not oxidized even in an oxidizing atmosphere. Furthermore, lanthanum chromite exhibits a coefficient of thermal expansion approaching that of intoria-stabilized zirconia.

Next, the anode 1, the solid electrolyte body 3, the porous substrate 7 with rib-like guide feathers on which the cathode 2 is formed, and the porous substrate 11 with rib-like guide feathers on which the interconnector layer 12 is formed are individually sintered. . After sintering, a porous prize substrate with double guide feathers7.
The side surfaces in contact with the fuel gas introduction pipe 4 and the oxidant gas introduction pipe 5 of No. 11 are gas-sealed using ceramic cement (ceramic seal 20).

Note that the porous substrate 11 with rib-shaped guide wings made of La(Sr)Mn03 does not necessarily have to be porous;
Since (Sr)Mn03 is reduced in a reducing atmosphere, the interconnector layer 12 using LaCrO3 is necessary even if it is made dense.

A fuel gas inlet pipe 4 is provided for sealing the reaction gas between the porous substrate 7 with rib-shaped guide wings and the porous substrate 11 with lip-shaped guide wings.
A glass seal 6 having a hole through which the oxidant gas introduction pipe 5 and the oxidant gas introduction pipe 5 pass is provided. The glass seal 6 is processed to have the same thickness as a single cell in which the anode 1, solid electrolyte body 3, and cathode 2 are laminated, and is made of soda glass. The glass seal 6 has a solid oxide fuel cell operating temperature of 100
At 0° C., it becomes liquid and liquid sealing becomes possible, and gas leakage from the reaction gas introduction pipe 4.5 can also be prevented.

Oxygen gas, which is an oxidizing gas, is passed through the gas hole 10A by the oxidizing gas introduction pipe 5 to the porous substrate l with rib-like guide feathers.
1 to the oxidant gas chamber 9 above. Hydrogen gas, which is a fuel gas, is introduced into the fuel gas chamber 8 on the lip-shaped porous substrate 7 with guide wings through the gas hole 10B by the fuel gas introduction pipe 4. As shown in FIG. 2, the oxidizer gas chamber 9 has guide vanes 19 with gas outlets arranged concentrically and shifted by 90 degrees.
A gas flow path is formed by A. The oxidant gas flows from the center to the periphery and is discharged from the gas outlet 16.

The fuel gas chamber 8 has a similar shape, but since the flow rate of the reactant gas is small, the guide vane 19B is shifted 180 degrees to separate the fuel gas and oxidant gas that have reached the periphery where the gas outlet is provided. burns and maintains the temperature of the fuel cell at a predetermined high temperature. It can also be used as a heat source for residual heat of reaction gas. The oxygen gas that has reached the cathode 2 is reduced and becomes oxygen ions, which diffuse through the solid electrolyte body 3. On the surface of the anode 1, the oxygen ions are oxidized and react with hydrogen gas to become water vapor. At this time, the free energy change of the reaction that generates water vapor from hydrogen gas and oxygen gas is converted into electrical energy, and a negative voltage is generated at the anode 1 and a positive voltage is generated at the cathode. The voltage per single cell is 0.5 to 0.
A predetermined voltage can be obtained by stacking them at 9V.

In a fuel cell having such a configuration, a porous substrate 7 with lip-shaped guide wings on which an anode 1, a solid electrolyte body 3, and a cathode 2 are formed, and a porous substrate 11 with rib-shaped guide wings on which an interconnector layer 12 is formed. This means that the porous substrate 7 with rib-like guide feathers and the porous substrate 11 with lip-like guide feathers can move freely relative to each other during the thermal expansion process, which reduces the generation of thermal stress. disappears. The glass seal used for gas sealing around the fuel gas inlet pipe 4 and the oxidant gas inlet pipe 5 solidifies after operation, but the linear expansion coefficient of glass is larger than that of zirconia or other electrode materials, so the glass seal occupies a small volume and does not cause cracking damage to other battery constituent materials, and the thermal stress caused by this glass seal is small, so the overall thermal stress is small.

Although the single cell has a disk shape in FIG. 2, it is not limited to this, and may be rectangular, elliptical, or polygonal.
Furthermore, the guide vanes 19A and 19B can be freely designed in consideration of gas distribution so as to maximize battery characteristics. Also,
It is also possible to combine the number of reaction gas introduction pipes into one instead of two. In this case, a double tube or two large tubes are used to separate and flow the two reaction gases inside the reaction gas introduction tube, which has the advantage of reducing the number of through holes.

FIG. 3 shows a modification of the guide vane. Reactive gases introduced from the central fuel gas introduction pipe 4 and oxidant gas introduction pipe 5 undergo a cell reaction while passing through the spiral guide vanes 19B.
flows to the outside of the cell along. The pitch of the X inner blades 19B needs to be selected at an optimal value depending on the diameter of the cell, but solid oxide fuel cells are less prone to cross leakage even when the gas differential pressure is increased, so even such a long gas flow path is sufficient for practical use. can. When the guide vanes 19B have a spiral shape, the gas can flow evenly through the single cell 13, and the exhaust gas can be collected in one place.

(Embodiment 2) FIG. 4 is a vertical cross-sectional view of a solid oxide fuel cell according to a different embodiment of the present invention. Separate plates 26 (reactive gas supply means) are alternately stacked, and a fuel gas introduction pipe 24 (reactive gas introduction pipe) and an oxidizing gas introduction pipe 25 (reactive gas introduction pipe) penetrate this stack. In addition, a fuel gas exhaust pipe and an oxidizing gas exhaust pipe pass through, but these are not shown. A glass seal 27 is placed between the upper and lower separate plates 26 (reactive gas supply means).
will be placed. The glass seal 27 is processed to have the same thickness as a single cell in which the anode 21, solid electrolyte plate 23, and cathode 22 are laminated, and has a ring shape.

Such a solid oxide fuel cell is prepared as follows. A circular solid electrolyte plate (100 to 1500 mm thick) 23 is formed using zirconia stabilized with ittria. The solid electrolyte plate 23 is connected to the fuel gas introduction pipe 24.
Oxidizing gas introduction pipe 25. It has through holes for fuel gas exhaust pipe and oxidant gas exhaust pipe. A porous anode 21 is formed by spraying nickel-zirconia (Ni ZrO□) cermet to a thickness of 100 mm on one main surface of the solid electrolyte plate 23 . Lanthanum manganite (LaMnOs) is sputtered on the other main surface of the solid electrolyte plate 23.
A porous cathode 22 having a thickness of 0 to 100 microns is formed.

The separate plate 26 is made of lanthanum chromite (LaCrOs).
), it is press-molded into a shape with through holes such as fuel gas introduction pipes, and is sintered densely. Lanthanum chromite has electronic conductivity and is stable without being oxidized even in an oxidizing atmosphere.

Additionally, lanthanum chromite exhibits a coefficient of thermal expansion close to that of ittria-stabilized zirconia.

The glass seal used is soda lime glass having a melting point of 900°C and a working temperature of 1000°C. Single cells and separate plates 26 are alternately stacked, and a fuel gas introduction pipe is inserted into the through hole. The operating temperature of the fuel cell is maintained at 1000°C. At this time, the glass seal 27 melts and gas sealing becomes possible. Hydrogen gas is supplied to the fuel gas introduction pipe 24, and air is supplied to the oxidizing gas introduction pipe 25, and each gas is supplied to the fuel gas chamber 28 and the oxidizing gas chamber of the single cell via gas holes 30A and 30B. Guided by 29.

The oxygen gas that has reached the cathode 22 is reduced, becomes oxygen ions, and diffuses within the solid electrolyte plate 23 .

Oxygen ions are oxidized on the surface of the anode 21 and react with hydrogen gas to become water vapor. At this time, the change in free energy of the reaction that generates water vapor from hydrogen gas and oxygen gas is converted into electrical energy, and a negative voltage is generated at the 7 node 21 and a positive voltage is generated at the cathode.

The positive and negative voltages of the single cell are connected in series by a separate plate 26. After the reaction, the fuel gas and oxidizing gas are exhausted through a fuel gas exhaust pipe and an oxidizing gas exhaust pipe (not shown). A gas seal is provided around the gas holes of the fuel gas exhaust pipe and the oxidant gas exhaust pipe and around the solid electrolyte plate 23.

(Embodiment 3) FIG. 5 is a longitudinal sectional view showing still another embodiment of the present invention. This case differs from the case shown in FIG. 4 in that a gas seal is not provided around the solid electrolyte vi23.

In this case, the reaction gas flows toward the periphery of the solid electrolyte plate 23 through the fuel gas introduction pipe 24 and the oxidant gas introduction pipe 25. Exhaust gas pipes are no longer required. Other details are the same as in the case of FIG.

〔Effect of the invention〕

According to this invention, there is provided a single cell in which a porous anode and a cathode are disposed on both sides of a solid electrolyte body, and a re-reaction gas of a fuel gas and an oxidizing gas are separately supplied to the single cell. A reactant gas supply means having a guide layer that guides the reactant gas from the center of the +11 principal surface toward the periphery in a solid oxide fuel cell comprising: and (2) a reaction gas introduction pipe that penetrates the center of the stack of the single cell and the reaction gas supply means in the stacking direction and diffuses the reaction gas from the gas hole on the side surface to the guide layer; and a glass seal disposed in at least the former of the spaces formed by the outer peripheral surface of the unit E1 and the reaction gas supply means, so that the reaction gas is guided to the guide layer of the reaction gas supply means. The gas flows from the center to the periphery, and as a result, the need for a gas seal between the unit cell and the reaction gas supply means is greatly reduced. Furthermore, as for the minimum required gas seal in the center or periphery of the cell stack between the single cell and the gas supply means, a glass seal that softens or melts during fuel cell operation is used. Each component of the battery is free to thermally expand as a whole.

A solid oxide fuel cell that can be shrunk and has excellent reliability without thermal damage can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a fuel cell according to an embodiment of the present invention, FIG. 2 is a cross-sectional view showing a guide layer of a fuel cell according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view showing a fuel cell according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing different guide layers of a fuel cell according to an embodiment of the invention, FIG. 4 is a longitudinal sectional view showing a fuel cell according to a different embodiment of the invention, and FIG. FIG. 6 is a longitudinal sectional view showing a fuel cell according to the present invention, and FIG. 6 is an exploded perspective view showing a conventional fuel cell. 4.5: Reaction gas introduction tube, 6: Glass seal, '$2 Figure 3 Yuya 2 Yugo A Figure 4 Figure 5

Claims (1)

[Scope of Claims] 1) A single cell in which a porous anode and a cathode are arranged on both main surfaces of a solid electrolyte body, and both reactant gases, a fuel gas and an oxidizing gas, are separately supplied to the single cell, and In a solid oxide fuel cell formed by laminating a reactant gas supply means for electrically connecting with a single cell, (1) a guide vane that guides the reactant gas from the center of the main surface toward the periphery; (2) a reaction gas introduction pipe that penetrates the center of the stack of the unit cell and the reaction gas supply means in the stacking direction and diffuses the reaction gas from the gas hole on the side surface to the guide vanes; and (3) a space formed by the inner peripheral surface of the single cell, the reaction gas supply means, and the reaction gas introduction pipe, and a space formed by the outer peripheral surface of the single cell and the reaction gas supply means, at least in the former. A solid oxide fuel cell characterized by comprising: a glass seal provided with a glass seal;