JPH11233127A - Disc laminate solid electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bring fuel into contact with an oxidizer over a wide area of cells to increase output density by supplying the fuel or oxidizer into a center gas diffusion space part by use of interconnectors having zigzag diffusion passages and made from a material of high porosity. SOLUTION: Fuel is fed into a zigzag diffusion passage 12b formed between a lower lid 5 and a second cell 1B by a fourth interconnector 12D and into a zigzag diffusion passage 12b formed between a separator 2 and a first cell 1A by a second interconnector 12B. Electric power is generated by supplying an oxidizer into the oxidizer supply passage 13b of a pipe 13 which projects outside of an upper lid 4, and feeding the oxidizer through the supply passage 13al of the pipe 13 into the zigzag diffusion passage 12b formed between the second cell and the separator 2 by a third interconnector 12c and into the zigzag diffusion passage 12b formed between the first cell 1A and the upper lid by a first interconnector.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk-stacked solid oxide fuel cell.

[0002]

2. Description of the Related Art Fuel cells are expected to be an important power generation technology because they not only have high power generation efficiency but also can provide co-generation of heat and have a flexible response to load fluctuations. In addition to this, since the generation of harmful exhaust gas is extremely small and the system is expected to be downsized in the future, it is necessary to avoid the conventional power supply system, that is, installing it in a place far away from the power consumption area and causing large power transmission loss. It is also expected to be a new distributed power source that cannot be obtained and can replace the current power generation system. Meanwhile, as a fuel cell, for example, a disk-stacked solid oxide fuel cell having a configuration as shown in an exploded perspective view shown in FIG. 1 and an assembled sectional view shown in FIG. 2 has been proposed.
As shown in FIG. 1, this battery has a required number of cells including a solid electrolyte (1a), a positive electrode (1b) and a negative electrode (1c) formed of a porous electrode component material provided on both disk surfaces, for example, No.
1, 2nd cell (1A), (1B), separator (2),
1, 2nd, 3rd, 4th interconnector (3A) (3B) (3
C) (3D), upper lid (4) and lower lid (5), fuel supply pipe (6) with supply port (6a) and fuel discharge pipe (7) with fuel discharge port (7a), supply port ( Oxidant (oxygen or air) supply pipe (8) with 8a) and outlet (9a)
And an oxidant discharge pipe (9) having And
As shown in the sectional view taken along the line AA ′ of FIG. 1 shown in FIG. 2 (a), the lower lid (5), the fourth interconnector (3D), the second cell (1B), the third interconnector (3C), separator (2), second interconnector (3B), first cell (1
A), the first interconnector (3A), and the top lid (4) are laminated in this order. In this way, the fuel supply port (6a) and the fuel discharge port (7a) are formed by the second interconnector (3B) between the unit cell (1A) and the separator (2).
And the fourth cell (1D) by the fourth interconnector (3D)
A fuel supply pipe (6) and a fuel discharge pipe (7) while a gas seal (10) is provided between each component so as to open into an internal space B formed between the lower cover (5) and the lower lid (5). And through holes (4a), (3a), (1d), (2a), and (3) provided at two opposing locations near the periphery of each component as shown in FIG.
c) Insert into (1d). In addition, FIG.
The oxidant supply port (8a) and the discharge port (9a) are formed between the separator (2) and the unit cell (1B) by the third interconnect (3c) as shown in the sectional view of the section B '. Interior space
A 'and 1st interconnector (3A) and 1st cell (1A)
Gas seal (10) between each component so as to open to the internal space B 'formed by
As shown in FIG. 1, the oxidant supply and discharge pipes (8) and (9) are provided with through holes (5a ') and (5a') (at right angles to the through holes of the fuel supply and discharge pipes (6) and (7)). 3d ') (1d')
(2a ') (3d') (1d ') Insert the gasket (10) on the outer peripheral surface so that fuel and air do not leak from each component through the gap between the components stacked last. Is done. Then, as shown in the power generation principle diagram in Fig. 3, the pipe (6)
(7), for example, hydrogen H2 as a fuel is supplied, and pipes (8), (9), for example, air as an oxidant, are supplied through the first and third interconnectors (3A) (3C). The positive electrode (1b) of the cell (1A) and the negative electrode (1
C) Supply power to the load R connected between them. This disk-stacked solid oxide fuel cell is made of only solid,
Unlike other types of phosphoric acid type fuel cells and furthermore, molten salt type fuel cells, there is no disadvantage in handling the liquid electrolyte, and since the operating temperature is as high as 800 to 1000 ° C., high power generation efficiency can be expected. In addition to this, it is also advantageous for installing a potting cycle using a steam turbine or the like and for cogeneration. Further, in this disk-stacked solid electrolyte fuel cell, as is clear from FIGS. 2 (a) and 2 (b), the electric current flows in a direction perpendicular to the disk surface of the positive and negative electrodes (1b) and (1c) and the solid electrolyte (1a). Because of the flow, the internal resistance depends almost exclusively on the thickness of the constituent materials. In addition, this type can not only reduce the thickness of the constituent materials in principle, but also can easily increase the electrode area per unit area, so that the output density per unit area can be improved and the disk structure is adopted. Therefore, the doctor blade method suitable for mass production and other wet methods can be used for the production of cells and the like, and there are various advantages such as a reduction in manufacturing cost. Further, according to the disk-stacked solid electrolyte fuel cell, there is an excellent effect that can solve various problems of the cylindrical fuel cell which is known as a basic type of the solid electrolyte fuel cell. That is, as shown in the perspective view of FIG. 4, the cylindrical fuel cell (ll) has a negative electrode (11b) and an electrolyte (11) on a porous tube (11a).
c) The components are laminated in the order of positive electrode (11d) and interconnector (11e) to form a unit cell or its assembly, and fuel and oxidant are flowed into and out of the tube (11a). Although it generates electricity, this type of fuel cell has the following problems. That is, current flows in the lateral direction (circumferential direction) along the electrode surface as shown by the arrow in FIG. 4, so that the current path becomes long and the internal resistance is large. The longest possible circular tube is required, but the length and thinness of the tube are limited in production, so the increase in power density is limited.In the case of a cylindrical type, it is necessary to laminate electrolyte, electrodes, etc. on a cylindrical tube However, there is a problem that a low-cost lamination method using a doctor blade method or the like easily causes cracking of an electrolyte or the like, so that a gas phase method having a high production cost must be adopted.
However, as described above, these problems have various advantages such as that the direction of the current is perpendicular to the panel surface of a unit cell or the like, that the thickness can be easily reduced, and the electrode area can be easily increased. It can be eliminated all at once by the disk lamination structure.

[0003]

However, on the other hand, disk-stacked solid oxide fuel cells also have disadvantages. That is, the fuel and the oxidant are supplied between the two points on the outer periphery of the disk, and the gas easily flows from the supply port to the discharge port in a short-circuit manner. It is difficult to effectively use the area. Therefore, even if the area of the unit cell is increased, the output density per unit area is not sufficiently improved. Further, since a layered interconnector is used, the current collecting distance is not sufficiently reduced and the internal resistance is not sufficiently reduced. Further, since the components are disk-shaped, the area can be easily increased in principle, but the mechanical strength decreases with the increase, and it is difficult to realize a large-capacity battery in this respect. In addition, since the operating temperature is as high as about 1000 ° C., it is difficult to balance the heat, and in order to obtain the heat balance, the supply gas must be heated to about 1000 ° C. using a heating device and supplied. Such high-temperature heating has various problems such as difficulty in practical use with current technology. Accordingly, the disk-stacked solid oxide fuel cell has attained the present without much active research and development, while having many advantages as described above.

The present invention solves the above-mentioned problems while maximizing the many advantages of the above-mentioned disk-stacked solid oxide fuel cell, and is superior to the conventional one in both production and performance. It is intended to provide a fuel cell and promote its practical use as a power supply source.

[0005]

A feature of the present invention is that, instead of the annular interconnector described with reference to FIG. 1, a central gas supply section (12a) as shown in FIG.
And an interconnector made of a material having a high porosity and having a zigzag diffusion passage (12b) so that the supplied gas communicating with the gas and opening at the outer peripheral portion is sufficiently supplied to the electrode surface. At the same time, the fuel or oxidant is supplied to the central gas diffusion space (12a).

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this manner, current can be collected over a wide area of the electrodes (1b) and (1c) of the unit cell (1), thereby shortening the current path and sufficiently lowering the internal resistance. Plan. By increasing the mechanical strength of the unit cell so as to increase the mechanical strength of the unit cell so as to become a strength reinforcing body of the unit cell, it is possible to facilitate the increase of the electrode area and at the same time, to facilitate the production and maintenance. The gas flows in a zig-zag diffusion path (12b) in a zig-zag fashion and acts as a good diffuser for fuel and the like, greatly facilitating the uniform flow of the gas and enabling effective use of the electrode area. The power generation efficiency is improved.

Further, the supply and discharge of the fuel and the oxidizing agent are not performed at two opposing and separated points near the periphery of the unit cell (1) as described above with reference to FIG. As shown in the sectional view, the gas supply unit (1) of the interconnector (12) is connected to the pipe (03) provided at the center of the unit cell (1) and other components as described above with reference to FIG.
The length, width, shape, etc. of the diffusion passage (12b) are adjusted so that the concentration of the supply gas becomes thinner toward the outer periphery of the cell (1) and then discharged to the outside. It is in consideration of this. This improves the power generation performance by increasing the fuel concentration in the center of the unit cell (1), and at the same time as the fuel and air pass through the diffusion passage (12b) of the interconnect (12). A so-called outer gas sealless structure is adopted so that the fuel is almost consumed, there is almost no influence on the fuel utilization rate, and the temperature rise due to the combustion of the gas released from the outer periphery is hardly a problem. . That is, the gas seal can be limited only between the fuel and oxidant supply pipe (13) provided at the center and the unit cell (1) and other components, so that a substantially complete seal including the outer periphery as in the conventional case is obtained. The production is remarkably facilitated by eliminating the need for In connecting and fixing each component machine by the gas seal material (10),
This is to reduce the trouble caused by the difference between the thermal expansion coefficients of the components and increase the degree of freedom in using the components.

Further, the temperature of the supplied gas is reduced by a fuel and air supply system from the center,
It is a point of solving the difficulty of heating and supplying to an operating temperature of about 1000 ° C. by a heating device as in the prior art, and has greatly advanced practical use. That is, as in the present invention, if the gas concentration is high at the center by flowing the fuel and the oxidant from the center of the power generation unit toward the outer periphery, and the gas concentration becomes leaner toward the outer periphery, the temperature is the highest at the center or the outer periphery. The distribution becomes lower as going in the direction, and the temperature at the center becomes higher than 1000 ° C. Therefore, some measures are required to maintain the heat balance. In the present invention, by reversing the above-mentioned point, which is a drawback, the fuel and the oxidant are heated by Joule heat based on the concentration difference, so that high-temperature supply which is difficult to put into practical use can be avoided. . In this manner, the practical application of the disk-stacked solid oxide fuel cell can be promoted by solving the problems of the various problems. Next, examples of the present invention will be described.

[0009]

FIG. 5, FIG. 6, and FIG. 7 show one embodiment of the present invention. FIG. 5 is an exploded perspective view, FIG. 6 is a plan view of an interconnector, and FIG. (A) and (b) are cross-sectional views of the fuel and oxidant supply pipes, and FIG. 8 is an assembled cross-sectional view, in which the same reference numerals as in FIGS. 1 and 2 denote equivalent parts. No.
In FIG. 5, (1A) and (1B) are unit cells, and (1a) is a solid electrolyte thereof, which is made of yttria-stabilized zirconia or yttria partially stabilized zirconia, for example.
(1b) is a positive electrode, for example, made of strontium or magnesium doped lanthanum manganate. (1c) is a negative electrode, which is made of, for example, nickel zirconia cermet. An oval pipe through-hole (1d) having the same diameter is provided at the center of the unit cells (1A) (1B). (2) is a separator made of lanthanum chromium doped with strontium or magnesium, or a nickel chromium alloy such as Inconel, the center of which is the same size as the pipe through hole of the unit cells (1A) and (1B). It has an elliptical pipe through hole (2a). (12A) (12B) (12
C) (12D) is the first, second, third, and fourth parts of this investigation.
Interconnector, for example, a separator (2)
The center of each of them has a zigzag with the same passage length as the circular gas supply part (12a) larger than the diameter of the cell through-hole as described above with reference to FIG. The gas supply part (12a) has an annular diffusion passage (12b) and is connected to the outer periphery. (4) is an upper lid, (5) is a lower lid, and at the center thereof, oval pipe through-holes (4a) and (5a) having the same dimensions as the pipe through-hole provided in the cell.
Having.

[0010] Next, (13) is a fuel and oxidant supply pipe, in which a fuel supply flow path (13
a) and an air supply channel (13b) whose lower end is closed. Also, as shown in the sectional views of the pipes shown in FIGS. 7 (a) and 7 (b), the fuel supply passage (13a) penetrates the pipe (13) at intervals corresponding to the interval of the fuel supply space. A plurality of fuel supply ports (13al) provided 1 to radially provided
The air supply flow path (13b) is provided with 1 to radially provided air supply paths (13bl) provided through the pipe (13) at intervals corresponding to the air supply space. Have.

The above components are assembled as follows. First, the supply pipe (13) is inserted into the oval through hole (5a) of the lower lid (5), and a seal made of a nickel alloy or the like is provided between the lower lid (5) and the pipe (13) as shown in FIG. After the material is gas-sealed (10), the fourth interconnector (12D) is inserted into the pipe (13) with the gas supply part (12a) at the center thereof inserted and overlapped, and the fuel supply path ( 13
a) is opened to the gas supply portion (12a) of the fourth interconnector (12D) as shown in FIG. Next, by inserting the pipe through hole (1d) into the pipe (13),
After stacking the second cell (1B) on the fourth interconnector (12D), connect the gas supply unit (12a) to the pipe (1D).
3) Insert the third interconnector (12C) on the second cell (1B). Then, a gas seal (13) is provided between the pipe (13) and the second cell (1B), and an air supply path (13bl) opens in the gas flooding section (12a) of the third interconnector (12C). To do. Then, after the separator (2) is further overlapped on the third interconnector (12C), the fuel supply path (13a) is connected to the gas supply section (12a) of the second interconnector (12B) in the same manner.
l) is opened and the air supply passage (13bl) is opened in the gas supply part (12a) of the first interconnector (12A).
Gas seal (1) in the order of interconnector (12B), first cell (1A), first interconnector (12A), top lid (4)
0) and superimposed to form a structure as shown in FIG. The fuel, for example, hydrogen H heated to a required temperature, is supplied to the fuel supply passage (13a) of the pipe (13) exposed outside the lower lid (5).
2 and the lower lid (5) and the second cell (1) are connected by the fourth interconnector (12D) through the fuel supply path (13al).
B) a zigzag diffusion passage (12b) formed between
Separator (2) and second by interconnector (12B)
A zigzag diffusion path formed between one cell (1A) (12
b). Also, an oxidant, for example, air heated to a required temperature is supplied to the oxidant supply passage (13b) of the pipe (13) projecting out of the upper lid (4), and the third interconnector is supplied through the supply passage (13al). (12C), a zigzag diffusion passage (12) formed between the second cell and the separator (2).
b) and the first cell (1A) by the first interconnector
It is sent to a zigzag diffusion passage (12b) formed between the upper lid and the upper lid to generate power.

In the above description, an example in which the gas diffusion passage (12b) of the ink connector has a zigzag shape has been described. However, the gas diffusion passage may have a spiral shape. As long as gas diffusion and current collection over a wide area of the battery are performed well, it can be formed using other channel shapes or materials. By using a foam or felt having a high porosity (60%, preferably 80% or more) for the interconnector, the current path between the separator and the electrode is increased to reduce the internal resistance, and the porous body is made of gas. Since it has the function of dispersing the gas, the gas dispersion efficiency can be improved. However, in this state, the gas flows from the gas supply section to the gas outlet in a short-circuit,
There is a possibility that gas may not evenly spread over the entire surface of the electrode.
For this purpose, for example, a porous disk and the above-mentioned zigzag gas diffusion passage serving as a gas flow baffle are used in combination.

[0013]

As described above, in the present invention, the interconnector is formed in a spiral shape from the center to the outer periphery.
The fuel and the oxidant can be brought into good contact with each other over a large area of the cell, and current can be collected over a much larger area than before. In addition, since the area can be easily increased by serving as a support, the effective electrode area per volume can be easily diffused to increase the output density. In addition, since the interconnect of the present invention can be formed by punching a plate, it is easy to manufacture, and since it is disk-shaped, it can be manufactured by a low-cost wet method such as a doctor blade method. In the present invention, fuel and oxidant are supplied from the center of the battery and discharged from the outer periphery, and the supply gas is heated using Joule heat based on a difference in power generation performance due to a difference in concentration between the fuel and the oxidant. I am doing it. Therefore,
At present, there is no need to consider the technically difficult high-temperature supply of gas, and further, after lamination, there is no need to provide a gas seal at the outer peripheral portion such as between the electrolyte and the interconnector or between the interconnector and the separator. Therefore, the manufacturing conditions are greatly relaxed, and low cost can be expected. In addition, since only a central portion is required to fix each component made of a different material using a sealing material, it is possible to provide a disk-stacked solid electrolyte fuel cell that solves the conventional problems such as easy use of materials having different thermal expansions. This will make it possible to greatly improve the performance as a power supply source.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a conventional device.

FIG. 2 is an explanatory diagram of a conventional device.

FIG. 3 is a diagram illustrating the principle of power generation by a fuel cell.

FIG. 4 is an explanatory view of a cylindrical fuel cell.

FIG. 5 is an explanatory diagram of one embodiment of the present invention.

FIG. 6 is an explanatory diagram of one embodiment of the present invention.

FIG. 7 is an explanatory diagram of one embodiment of the present invention.

FIG. 8 is an explanatory diagram of one embodiment of the present invention.

[Explanation of symbols]

(1A) (1B) Single cell (1a) Solid electrolyte (1b) Positive electrode (1c) Negative electrode (1d) Pipe through hole (2) Separator (3A) (3B) (3C) (3D) First and second , 3rd, 4th interconnector (4) Upper lid (4a) Pipe through hole (5) Lower lid (5a) Pipe through hole (6) Fuel supply pipe, (6a) Supply port (7) Fuel discharge pipe (7a) Discharge port (8) Oxidant supply pipe (8a) Supply port (9) Oxidant discharge pipe (9a) Discharge port (10) Gas seal material (11a) Support tube (11b) Negative electrode (11c) Electrolyte (11d) Positive Electrode (11e) Interconnector (12A) (12B) (12C) (12D) (12) First, Second, Second
Third and fourth interconnectors (12a) Gas supply part (12b) Zigzag diffusion passage (13) Fuel and oxidant supply pipe (13a) Fuel supply passage (13al) Supply passage, (13b) Oxidant supply passage ( 13bl) supply channel,

Claims (1)

[Claims] 1. A unit cell in which a positive electrode substance is disposed on one side of a disc-shaped solid electrolyte and a negative electrode substance is disposed on the other side, and a gas supply part provided at the center and an opening communicate with the gas supply part at the outer peripheral part. In a disk-stacked solid electrolyte fuel cell in which fuel gas and oxidant gas diffusion passages are provided and interconnects are interposed between the upper lid and the lower lid with a disk-shaped separator interposed therebetween, the interconnectors have an interconnector of 80% or more. In the center of the laminate, a fuel gas supply path communicating with the gas supply section of the interconnector on the positive electrode side and a gas supply section of the interconnector on the negative electrode side are provided. An oxidizing gas supply passage communicating with each of the oxidizing gas supply passages is provided, and the fuel gas supply passage and the oxidizing gas supply passage each include a plurality of diffusion passages that progress in a zigzag shape in the circumferential direction.
The fuel gas and the oxidizing gas are supplied to the positive electrode side such that the concentration of the diffusion passage at the center of the circle of the diffusion passage of the fuel gas and the oxidizing gas is high, and the concentration decreases toward the outer periphery. And a disk-stacked solid electrolyte fuel cell characterized by flowing through the gas diffusion passage of the negative electrode side interconnector and discharging from the outer peripheral portion.