JP3153901B2 - Disc-stacked solid electrolyte fuel cell - Google Patents

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 not only allows the thickness of the constituent materials to be reduced in principle, but also facilitates an increase in 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 oxide fuel cell, there is an excellent effect that can solve various problems of the cylindrical fuel cell known as a basic type of the solid oxide 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 stacked 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 its length and thinness are limited in production, so there is a limit to increase in power density. 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, these problems have various advantages such as the direction of the current is perpendicular to the panel surface of a unit cell or the like as described above, the thickness can be easily reduced, and the electrode area can be easily increased. It is eliminated 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] As a result, current can be collected over a wide area of the electrodes (1b) and (1c) of the unit cell (1), and the current path is shortened to sufficiently reduce the internal resistance. 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 increases the fuel concentration at the center of the unit cell (1) to improve the power generation performance, and at the same time as the fuel and air pass through the diffusion passage (12b) of the interconnector (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 Further, in connecting and fixing each component machine by the gas seal material (10), troubles based on the difference in thermal expansion coefficient of each component are reduced, and the degree of freedom of use of the components is increased.

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. In material (10)
After the gas sealing , the fourth interconnector (12D) is inserted into the pipe (13) with the gas supply part (12a) at the center thereof overlapped, and the fuel supply path (13a) of the co-supply pipe (13) is formed. And the fourth interconnector (12
An opening is provided in the gas supply section (12a) of D). Next, by inserting the pipe through hole (1d) into the pipe (13), the second cell (1B) is superimposed on the fourth interconnector (12D), and then the gas supply section (12a) is connected to the pipe. (13), and superimpose the third interconnector (12C) on the second cell (1B). And the pipe (1
A gas sealing material (10) is used between 3) and the second cell (1B) .
Gas seal and the third interconnector (12
The air supply channel (13bl) should be open to the gas flooding section (12a) in C). Then, the third interconnector (12
C) After the separator (2) is superimposed on the first interconnector (12A), the fuel supply passage (13al) opens in the gas supply section (12a) of the second interconnector (12B) in the same manner. Air supply path (13b) to the gas supply section (12a)
l) the second interconnector (12B), so that the opening
The first unit cell (1A), the first interconnector (12A), and the top cover (4) are superposed in this order while being gas-sealed by the gas seal material (10) , as shown in FIG. Then, a fuel such as hydrogen H2 heated to a required temperature is supplied to a fuel supply passage (13a) of a pipe (13) exposed outside the lower lid (5).
The lower lid (5) and the second cell (1) are supplied 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 cover (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, the gas diffusion passage (12b) of the interconnector has a zigzag shape . This
By doing so, it has a reinforcing force for the mechanical strength of the unit cell, and furthermore, gas diffusion to the entire surface of the cell and current collection over a wide area of the cell are performed well. By using a foam or felt with a high porosity ( 80% or more porosity ) for the interconnector, the current path between the separator and the electrode is increased to reduce the internal resistance, Since it acts to disperse, gas dispersion efficiency can be improved.

[0013]

Since in the present invention as described above, according to the present invention has a zigzag toward the outer periphery from the center of the interconnector,
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 interconnector 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 an inexpensive 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. Accordingly, it is not necessary to consider the technically difficult high-temperature supply of gas at present, 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,

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 8/02 H01M 8/12

Claims (1)

(57) [Claims] 1. A unit cell in which a positive electrode material is disposed on one surface of a disc-shaped solid electrolyte and a negative electrode material is disposed on the other surface are connected to a fuel gas supply portion provided at the center thereof and communicate with the fuel gas supply portion. A fuel gas diffusion passage having a diffusion passage
Connector and centrally provided oxidant gas supply
And a diffusion passage communicating with this and opening at the outer periphery.
Interconnect interconnect with the oxidant gas diffusion path
By pinching the further via a disc-shaped separator, the disc stacking the solid oxide fuel cell stack between the upper cover and the lower cover, the interconnector is composed of foam or felt of 80% or more of porosity, mainly Fuel gas provided
A supply part and a fuel gas communicating with the supply part and opening at an outer peripheral part;
An oxidizing gas supply unit provided in the diffusion passage and the center;
Oxidant gas diffusion passage opening at the outer peripheral portion
The road is divided into a plurality of zigzag
Formed by diffusion channels and supplied to their respective central parts
The concentration of fuel gas and oxidizing gas in the diffusion passage
The disc-stacked solid electrolyte fuel cell has a special feature that the structure becomes lower as it goes.