JPH02299167A - Solid electrolyte type fuel cell stack - Google Patents

Abstract

PURPOSE:To facilitate the serial connection and parallel connection of stacks together and simply obtain the external output by providing a slit at the depth reaching the first electrode layer from the surface, and forming an output terminal layer at the preset thickness on the first electrode layer in the slit. CONSTITUTION:A slit 27 extended with the fixed width in the direction parallel with the axis of a support pipe 21 is formed on a fuel cell unit 25 formed on one end side of a solid electrolyte type fuel cell stack 20 at the depth reaching the surface of the innermost air electrode layer 22 by scraping the outermost fuel electrode layer 24 and the intermediate solid electrolyte layer 23. An output terminal layer 28 made of a raw material nearly similar to that of an interconnector 26 is formed on the air electrode layer 22 of the slit 27 at the noncontact state with the fuel electrode layer 24 so that its end section on the cell outer periphery side is kept at the same height as the outer periphery of the outermost fuel electrode layer 24 or the height slightly protruded to the outside. The external output is easily obtained. The serial connection and parallel connection can be optionally performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a solid oxide fuel cell stack in which a plurality of individual fuel cells are connected in series around the outer periphery of a single cylindrical support tube. It is.

Conventional technology The voltage generated from each fuel cell that makes up a solid oxide fuel cell is about 1V, which is too low to be practical. In order to do this, it is necessary to connect them in parallel as well.

Methods for connecting a plurality of single fuel cells in series include an internal series system shown in FIG. 4 and an external series system shown in FIG. 5.

First, in the internal series type, a fuel cell unit 5 formed by laminating a first electrode layer 2, a solid electrolyte layer 3, and a second electrode layer 4 in this order is supported on the outer periphery of a porous cylindrical support tube 1. A plurality of fuel cell units 5 and 5 are formed with a predetermined length in the axial direction of the tube 1 and gaps are provided between adjacent fuel cell units 5 and 5, and each of these fuel cell units 5 is provided with an interconnector 6 in the mutual gap. , the first electrode layer 2 of one adjacent fuel cell unit 5 and the second electrode layer 4 of the other fuel cell unit 5 are connected in series. A first output lead part 7 connected to the first electrode layer 2 of the fuel cell unit 5 formed at one end (the left end in FIG. 4) of the support tube 1 is connected to both ends of the support tube 1. is formed on the outer periphery of the , and at the other end,
The second N pole 114 of the fuel cell unit 5 formed at the end thereof
A second output lead portion 8 electrically connected to the second output lead portion 8 is formed, respectively.
As a whole, a so-called fuel cell stack 9 having a rod shape is formed.

On the other hand, in the fuel cell unit 15 used by external series connection, the first electrode layer 1
2. It has a structure in which a solid electrolyte layer 13 and a second electrode layer 14 are laminated in this order, and a part of the outer periphery (the upper part of each in FIG. 5) of each fuel cell unit 15 is covered with a first electrode from the surface. A slit 16 with a depth of up to 1112 mm is formed parallel to the axis over the entire length, and this slit 16
An interconnector 17 is located inside the first electrode 1112.
While being connected to the second electrode layer 14, the second electrode layer 14 is provided in a non-contact state.

Then, the plurality of fuel cells 15 are arranged in parallel, and the tip of one interconnector 17 of each adjacent fuel cell unit 15.15 is connected to the second electrode layer 14 on the outer periphery of the other fuel cell unit 15. They are connected in series by being brought into contact with each other directly or with a buffer material 18 such as conductive felt interposed therebetween.

Problem to be Solved by the Invention However, among the conventional types of connecting individual fuel cells in series, the output voltage of the fuel cell stack 9 in the former internal series type is the same as that of the single cylindrical support tube. It is determined by the number of single fuel cells 5 that can be formed in a single fuel cell unit 5, and the required minimum length and support 1i! of each single fuel cell unit 5! The maximum output was determined by the length that could be manufactured.

In addition, in order to output externally from the fuel cell stack 9, it is necessary to provide a first output lead part 7 and a second output lead part 8, which are output terminals, at both ends of the support tube. The path through which electricity flows becomes longer by .8,
There was a problem in that as the internal resistance increased, the effective length of the support tube 1 became shorter by the length of the Ryogawa force lead portion 7.8, and the number of fuel cells 5 that could be formed was reduced. Furthermore, when trying to connect the fuel cell stacks 9 in series to increase the output voltage, the fuel cell stacks 9
It is necessary to connect the first output lead part 7 formed at both ends of the fuel cell stack 9 to the second output lead part 8 of the other fuel cell stack 9 by external wiring, which poses a problem in that the connection work becomes complicated.

On the other hand, in the case of the latter external series type, the entire length of the support tube 11 can be used as a single fuel cell 15 without waste, but only one support tube! Since one single fuel cell 15 is formed on the fuel cell 11, the output voltage per fuel cell is as low as about 1V. Therefore, in order to extract a desired voltage, it is necessary to connect a large number of fuel cells 15 in series, resulting in a problem that the assembly of fuel cells 15 becomes large.

The present invention has been made in view of the above circumstances, and provides a solid oxide fuel cell stack that is an internal series fuel cell stack that allows for easy series and parallel connections between stacks, as well as easy external output. It is intended to.

Means for Solving the Problems In order to achieve the above object, the present invention provides a fuel cell in which a first electrode layer, a solid electrolyte layer, and a second electrode layer are laminated in this order from the inside on the outer periphery of a cylindrical support tube. A plurality of fuel cell units are formed with a predetermined length in the axial direction and a gap is provided between adjacent fuel cell units, and a first electrode layer of one fuel cell unit and the other fuel cell unit are adjacent to each other in the axial direction. In a solid oxide fuel cell stack in which a conductive connector is formed in each gap on the outer periphery of a support tube and connected in series, the plurality of fuel cells connected in series are connected to the second electrode layer. The single fuel cell formed at least at one end of the support tube is provided with a slit deep enough to reach from the surface to the first electrode layer, and an output terminal layer is formed on the first electrode layer in this slit in a predetermined manner. It is characterized by being formed thickly.

Function As described above, a solid oxide fuel cell stack is formed around the outer periphery of one support tube by connecting a plurality of individual fuel cells in series with each other using conductive connectors, and A part of the output terminal layer provided in the slit connected to the innermost first electrode layer is in a non-contact state with the outermost second electrode layer on the outer peripheral surface of the single fuel cell formed in Since the output terminal layer is disposed at the end, external output is facilitated, and when a plurality of these solid oxide fuel cell stacks are connected in series, the output terminal layer formed at the end is connected to the adjacent The output terminal layers are arranged close to each other and parallel to each other, for example, alternately on the left and right sides, so as to contact the second electrode layers of the single fuel cells at the ends of the solid oxide fuel cell stack. Then, the output terminal layer of each single fuel cell comes into contact with the 21st pole layer at the end of another adjacent solid oxide fuel cell stack, and is easily connected in series. Furthermore, since it can be directly connected without going through the output lead section, power loss due to internal resistance is reduced.

Furthermore, if they are provided at both ends of the solid oxide fuel cell stack, the second electrode layer and output terminal layer of the single fuel cell at each end can be used alternatively, allowing for arbitrary series and parallel connections. Moreover, series-parallel connection is also easy, and desired high voltage and high output can be easily obtained.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 3.

The solid oxide fuel cell stack 2o has an air electrode layer 22 on the outer periphery of one long cylindrical support tube 21, and an air electrode layer 22 on the inside.
A plurality of fuel cell units 25 are formed in which a solid electrolyte layer 23 and a fuel electrode layer 24 are laminated in this order, with a predetermined length in the axial direction of the support tube 21 and with a predetermined gap between adjacent fuel cell units 25 and 25. At the same time, an interconnector 26 is connected to connect the air electrode layer 22 of one of the fuel cell units 25 adjacent to each other in the axial direction and the fuel electrode layer 24 of the other fuel cell unit 25. are formed in each gap on the outer periphery of the support tube 21, and each fuel cell unit 2
5 are connected in series to form one rod shape.

Further, the support tube 21 is made of an alumina tube, a calcia stabilized zirconia tube (C3Z), etc., which has high mechanical strength, excellent gas permeability, and is lightweight. ! The innermost air electrode layer 22 of each fuel cell unit 25 formed on the outer periphery of the fuel cell 21 is made of, for example, velorskite, which is chemically stable in a high-temperature oxidizing atmosphere, has high conductivity, and has excellent gas permeability. It is made of a type lanthanum-based composite oxide. Further, the solid electrolyte layer 23
For example, yttria-stabilized zirconia (
YSZ) etc., and furthermore, the outermost fuel electrode layer 2
4 is made of porous and electronically conductive material such as cermet of nickel or nickel and zirconia.

Further, the interconnector 21. It is chemically stable in an il-oxidizing reducing atmosphere and has high electronic conductivity.
It is formed of a nickel-based alloy, a provskite-type lanthanum-based composite oxide (for example, LaCr03), or the like.

One end side of the solid oxide fuel cell stack 20 (
Single fuel cell 25 formed on the left end side in Fig. 1
includes an outermost fuel electrode layer 24 and an intermediate solid electrolyte layer 2.
6 is cut to form a slit 27 that has a depth that reaches the surface of the innermost air electrode layer 22 and that extends with a constant width in a direction parallel to the axis of the support tube 21. On the air electrode layer 22, an output terminal layer 28 made of substantially the same material as the interconnector 26 is provided.
A height that is in a non-contact state with the fuel electrode layer 24 and whose outer peripheral end of the cell (the upper end in FIG. 2) is at the same height as the outer peripheral surface of the outermost fuel electrode layer 24 or slightly protrudes outward from this. It is formed.

Next, the operation of this embodiment configured as described above will be explained.

The solid oxide fuel cell stack 20 is used while being housed in a casing (not shown), and oxygen or air is supplied to the space inside the cylindrical support tube 21, which is connected in series. When a fuel gas such as hydrogen (H2) or -carbon oxide (Co) is supplied to the space inside the casing around each fuel cell unit 25, a solid electrolyte 23 is sandwiched between each fuel cell unit 25. The solid electrolyte layer 23 is arranged so as to balance the oxygen concentration in the atmosphere on both sides.
Oxidation and reduction reactions occur through the ions, producing electricity.

Since the electricity generated in each fuel cell unit 26 is connected in series via the interconnector 26, the output terminal 118 connected to the air electrode layer 22 of the fuel cell unit 25 at one end, and the fuel cell unit 25 at the other end. The fuel electrode layer 24 of the cell unit 25 serves as the anode and cathode of the entire solid oxide fuel cell stack 20, and the voltage is output as the sum of the number of fuel cell units 25 connected in series.

In addition, when connecting the solid oxide fuel cell stacks 20 in series to obtain an even higher voltage, the output terminal layer 28 of the fuel cell unit 25 formed at one end of each solid oxide fuel cell stack 2o of the output terminal layer 28 of each solid oxide fuel cell stack 20 so as to contact the fuel electrode WA24 of the fuel cell unit 25 formed at the end of each adjacent other solid oxide fuel cell stack 20. For example, the positions should be alternated on the left and right,
When arranged close to each other in parallel, each fuel cell unit 2
The eight output terminal layers 28 are easily connected by contacting the fuel electrode layer 24 of the fuel cell unit 25 at the end of another adjacent solid oxide fuel cell stack 20, and external wiring etc. for connection are easily connected. As many solid oxide fuel cell stacks 20 as necessary to obtain a desired voltage can be easily connected without using the solid oxide fuel cell stack 20 (see FIG. 3).

Further, the output terminal layer 28 can be formed on both of the fuel cell units 25 and 25 formed at both ends of the solid oxide fuel cell stack, respectively. In this case,
It becomes possible to arbitrarily select the polarity at both ends of the solid electrolyte fuel cell stack 20, and by appropriately determining the position and number of the output terminals M28 formed on the fuel cell units 25 and 25 at both ends, the solid electrolyte There is no need to consider arranging the orientation of the solid oxide fuel cell stacks 20 alternately on the left and right sides, and when connecting the solid oxide fuel cell stacks 20 in series or in parallel, the output terminal layer 28 is The connection method can be selected depending on whether the fuel electrode layer 24 or the output terminal 1128 of the adjacent solid oxide fuel cell stack 20 is to be contacted, and the series-parallel connection of the entire assembly of the solid oxide fuel cell stacks 20 is also possible. It becomes easier.

In addition, in the above embodiment, the case where the output terminal layer 28 was provided on the fuel cell unit 25 formed at the end of the solid oxide fuel cell stack 20 was explained, but the output terminal layer 28 was provided in the middle part of the solid oxide fuel cell stack 20. The output terminal layer 28 can also be formed on the single fuel cell 25 formed in the fuel cell unit 25 .

In addition, in the above embodiment, the solid oxide fuel cell stack 20 has the air electrode layer 22 formed inside the solid electrolyte 23 and the fuel electrode layer 24 formed outside the solid electrolyte 23, but the fuel electrode layer 22 is formed inside the solid electrolyte 23. This can be similarly carried out in the case of a solid oxide fuel cell stack in which an air electrode is formed on the outside.

DETAILED DESCRIPTION OF THE INVENTION As described above, the present invention includes a first electrode layer, a solid electrolyte layer, and a second electrode layer arranged on the outer periphery of a cylindrical support tube in order from the inside. ! ! In a solid oxide fuel cell stack in which a plurality of fuel cells of the following types are connected in series with an interconnector provided between them, the fuel cell is formed at at least one end of a support tube of the plurality of fuel cells. Since a slit deep enough to reach the first electrode layer is formed in the single unit and the output terminal layer is formed there, the output lead parts that were conventionally provided at both ends of the solid oxide fuel cell stack are no longer required, and the support tube Since the total length can be used effectively and the number of single fuel cells that can be formed on one support tube increases, the output voltage per stack can be increased. Furthermore, since an output lead section is not required, power loss due to internal resistance can be reduced.

In addition, when solid oxide fuel cell stacks are connected in series, the output terminal layer at one end of each solid oxide fuel cell stack is connected to the fuel cell at the end of each adjacent solid oxide fuel cell stack. By simply arranging them so that they are in contact with the second electrode layer on the outer periphery of the unit, connection can be easily made without using external wiring, etc. Also, solid oxide fuel cell stacks can be easily connected in parallel, so that the desired voltage can be achieved. can be easily obtained.

[Brief explanation of drawings]

1 to 3 show one embodiment of the present invention, in which FIG. 1 is a perspective view of a solid oxide fuel cell stack, FIG. 2 is a cross-sectional side view, and FIG. 3 is a series connection between stacks. Schematic diagrams showing connections, Figures 4 and 5 respectively show conventional examples. Figure 4 is a cross-sectional side view showing how to connect an internal series fuel cell, and Figure 5 shows an external series connection. FIG. 3 is a cross-sectional front view showing the method. 20...Solid electrolyte fuel cell stack, 21...
- Support tube, 22... Air electrode layer, 23... Solid electrolyte layer, 24... Fuel electrode layer, 25... Fuel cell unit, 26... Interconnector, 27...
・Slit, 28...output terminal layer.

Claims (1)

[Claims] A fuel cell unit in which a first electrode layer, a solid electrolyte layer, and a second electrode layer are stacked in this order from the inside is placed around the outer periphery of a cylindrical support tube, with a predetermined length in the axial direction and a gap between adjacent fuel cell units. A plurality of conductive connectors are provided on the outer periphery of the support tube to connect the first electrode layer of one single fuel cell and the second electrode layer of the other single fuel cell that are adjacent to each other in the axial direction. In a solid oxide fuel cell stack formed in a gap and connected in series, the fuel cell unit formed at least at one end of the support tube among the plurality of series-connected fuel cells A solid oxide fuel cell stack characterized in that a slit is provided with a depth reaching one electrode layer, and an output terminal layer is formed to a predetermined thickness on a first electrode layer within the slit.