JPH02312166A - Structure of solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To obtain a high output fuel cell of small inner resistance by providing a conductive supporting body with a function as connecting tools for electrically connecting plural single cells, which supporting body keeps plural single cells being connected in parallel to each other. CONSTITUTION:Each single cell 1 is held while in contact with the inner peripheral face of the tubular portion 8c of a supporting body 8, and a stack comprises five single cells 1 connected in parallel to each other. In each stack, a plate- shaped portion 8a located on the center side of the single cell 1 is integrated with the tubular portion 8c of adjacent other stack, and also the tubular portion 8c surrounding the single cell 1 is integrated with the plate-shaped portion 8a surrounded by the single cell 1 in the other stack, and so plural stacks are connected in series to each other by putting each plate-shaped portion 8a as one electrode and each tubular portion 8c as the other electrode in conduction to each other sequentially. As a result, the supporting body is used as parts with integrated structure serving also as connecting tools for the group of single cells, and besides the cross area where current are caused to flow is wide so that the inner resistance is reduced and the current passage is shortened. High output is thus achieved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a fuel cell structure in which a plurality of single cells are connected in parallel and the aggregates are further connected in series. The present invention relates to a fuel cell mainly consisting of a single cell having an oxygen electrode and a fuel electrode provided on the inner and outer surfaces of an electrolyte.

Conventional Technology As is well known, solid electrolyte fuel cells utilize the fact that materials such as yttria-stabilized zirconia (YSZ) exhibit oxygen ion conductivity at high temperatures of around 1000°C. 4113m has a porous oxygen electrode made of perovskite-type lanthanum-based composite oxide, etc., and a porous fuel electrode made of nickel, nickel alloy, Ni-2rO2 cermet, etc., with a solid electrolyte such as YSz in between. , oxidizing gas such as air or oxygen gas is flowed to the oxygen electrode side under high temperature conditions, while fuel gas such as hydrogen gas or carbon monoxide gas is flowed to the fuel electrode side, thereby causing oxidation/reduction reactions via the solid electrolyte. Electric power is obtained by

The voltage obtained by this type of single cell is only about 1μ at most, so for practical use it is necessary to connect a large number of LTL batteries in series and parallel.
Forming 11 batteries into a cylindrical shape and connecting them in series and parallel 4
Various structures such as 113Th and a flat plate type in which a large number of single cells are formed between conductive plates serving as interconnectors and stacked in large numbers have been developed and studied. Among these structures, the flat plate type has the advantage of making the whole structure more compact, but it also has problems such as difficulty in sealing to prevent mixing of oxidizing gas and fuel gas, as well as a lack of ease of manufacture. Therefore, the cylindrical type is highly practical.

Conventionally, as a structure for obtaining the necessary electromotive force using cylindrical cells, a large number of cells are arranged in a vertical and horizontal matrix. For example, each cell is connected in series in the vertical direction, and each cell is connected in series in the horizontal direction. A structure in which batteries are connected in parallel is known. However, in such a structure, if an abnormality occurs in one of the Qi cells and that cell no longer generates an electromotive force, the entire group of cells connected in series including that cell will become inoperable or A problem arises in that the internal resistance of the unit cell group increases significantly and the power generation efficiency decreases. The applicant has already proposed a structure that can solve these problems, and its basic structure consists of arranging a large number of cylindrical cells around the outer periphery of a conductive internal current collector. , the electrode on the inner circumferential side of each unit cell is connected to the internal current collector by an interconnector, and the entire IIS battery is surrounded by a cylindrical external current collector provided approximately concentrically with the internal current collector, and each unit cell is The electrode on the outer circumferential side is electrically connected to an external current collector. Note that a structure in which a plurality of unit cells are connected in this manner is called a stack.

Problems to be Solved by the Invention The above-mentioned stack can be assembled into a fuel cell by connecting a plurality of stacks in series and parallel, but in that case, each stack has an internal current collector as one electrode, and an external 'JTs collector. Since it is considered to be an independent power generation element with the other electrode as the other electrode, the structure for connecting them in series is to have at least one end of the internal collector protrude in the axial direction, and a conductive element extending radially from the protrusion. A conceivable structure is that the connector is brought into contact with the outer surface of the external current collector of another stack with a cushioning conductive material such as nickel felt interposed therebetween. However, in such a structure, the current generated in each stack is concentrated in the connector provided at one end of the stack, resulting in a high current density at the connector, and the external concentration of the connector and other stacks is high. There are problems such as an increase in contact resistance between electrons and a decrease in the overall power generation efficiency of the fuel cell.

This invention was made against the background of the above-mentioned circumstances, and aims to provide a fuel cell with good power generation efficiency and high output.

Means for Solving the Problems In order to achieve the above object, the present invention includes a cylindrical part in which a slit is formed along the axial direction, and a cylindrical part provided protruding in the radial direction on the outer surface of the cylindrical part. A plurality of 1$ batteries each having a support body and having one electrode electrically connected to the plate-like part surround the tip of the plate-like part. In addition to the arrangement, these unit cells are housed in a cylindrical part of another conductive support, and the other electrode of each unit cell is electrically connected to the cylindrical part.

Function: Even in the fuel cell having the structure according to the present invention, an electromotive force is generated by flowing the oxidizing gas and the fuel gas on both sides of the solid electrolyte of each unit cell. The plurality of unit cells are arranged around the tip of the plate-like part of the conductive support with one electrode electrically connected to the plate-like part, and in this state, the outer periphery is connected to the other conductive support. The other electrode is electrically connected to the cylindrical part of the support body, and the cells housed in the cylindrical part of the predetermined support are connected in parallel, and the single cells of the group are connected to each other in parallel. It is connected in series to another group of adjacent unit cells via a support. As a result, the support is an integral part that can accommodate the connectors for the cell groups, and the cross-sectional area of the current-flowing part is wide, so the resistance associated with connecting the cell groups is extremely small. The current flow path between the cell groups becomes shorter. Therefore, in the fuel cell of the present invention, the factors that increase the internal resistance and the factors that increase the loss are reduced, so that high output can be achieved.

Example Next, embodiments of the invention will be described with reference to the drawings.

Figure tA1 is a cross-sectional front view showing a part of the fuel cell according to the present invention, in which a plurality of (five in the figure) single cells 1 form one stack 2, which are connected in series.

That is, each unit cell 1 is of a so-called cylindrical type, an example of which is schematically shown in FIG. 2, and is made of alumina (^1!).
An oxygen electrode 4 made of a perovskite-type lanthanum-based composite oxide or the like is formed on the outer periphery of a ceramic support tube 3 formed in a porous LIT structure using a method such as 203), and a part of its outer surface is made of a nickel alloy or the like. An interconnector 5 made of a material made of
A solid electrolyte 6 made of materials such as the like is formed. Further, a fuel electrode 7 made of a material such as a nickel alloy or a cermet of nickel and zirconia is connected to the interconnector 5.
The solid electrolyte 6 is formed around the outer periphery of the solid electrolyte 6 so as to be in a non-conductive state.

Therefore, in the cell 1, an oxidizing gas such as air is allowed to flow on the inner circumferential side, while a fuel gas such as hydrogen gas is allowed to flow on the outer circumferential side. An electromotive force is generated through an electrochemical reaction.

The support 8 for holding the cell 1 in each stack 2 has a @ structure as shown in FIG. In other words, the support 8 is made of a material that is conductive and highly resistant to hydrogen embrittlement, such as nickel alloy or 3# conductive ceramic, and has a length that is about the same as or longer than the length of the cell 1. One side of the substantially rectangular plate-like part 8a of the plate-like part 8a has an inner diameter that encloses a plurality of (for example, five) single cells 1 arranged on the outer periphery of the tip of the plate-like part 8a. A cylindrical portion 8C is formed with a slit 8b along the axial direction that is wider than the thickness of the plate.

Each unit cell 1 is arranged on the outer circumferential side of the plate-like part 8a with the interconnector 5 abutted against the outer circumferential surface of the tip of the plate-like part 8a with a conductive MIi material, for example, nickel felt 9 interposed therebetween. The outer periphery of these single cells 1 is surrounded by a cylindrical portion 8C of another support 8. As mentioned above, the cylindrical portion 8C has an inner diameter that is large enough to accommodate five single cells 1, and its inner peripheral surface is conductive! av! Attach E material such as nickel felt 10,
The outer surface of each q1 lightning pond 1, that is, the fuel electrode 7 is brought into contact with this. In addition, the plate-like part 8a is formed by the slit 8 of the cylindrical part 8C.
b and penetrates the cylindrical portion 8C.

Therefore, each unit cell 1 has its interconnector 5 attached to the outer circumferential surface of the plate-like portion 8a of one of the supports 8 using a nickel felt 9.
The fuel electrode 7 on the outer peripheral side is held in contact with the inner peripheral surface of the cylindrical portion 8C of the other support 8 through the nickel felt 10. Connect five cells 1 in parallel to form a stack 2
is configured. In each stack 2, a plate-like part 8a located on the center side of the unit cell 1 is integrated with a cylindrical part 8C of another adjacent stack 2, and a cylindrical part 8C surrounding the unit cell 1 is further integrated with another cylindrical part 8C. Since it is integrated with the plate-like part 8a surrounded by the unit cells 1 in the stack 2, the plurality of stacks 2 have a plate-like part 8a which becomes one electrode and a cylindrical part 8C which becomes the other electrode. They are connected in series with successive conduction.

In the M4 fuel cell described above, the solid electrolyte 6 is formed by flowing an oxidizing gas containing oxygen gas such as air into the inner circumference of each cell 1, and flowing a fuel gas such as hydrogen gas into the outer circumference. An electromotive force is generated by the oxidation/reduction reaction,
In each stack 2, the oxygen electrode 4 of the unit cell 1 is electrically connected to the plate part 8a via the interconnector 5, so that the plate part 8a is on the anode side and the cylindrical part 8C is on the cathode side, and further adjacent to each other. Since the stacks 2 are electrically connected to each other by the plate-like portion 8a and the cylindrical portion 8c on the side of the other stack 2 that is integral with this, the current flows through the plate-like portion 8a. The cylindrical portion 8C of the stack 2 on the starting end side is used as a cathode, and the plate portion 8a of the stack 2 on the terminal side is used as an anode. Therefore, current flows between adjacent stacks 2 through the plate-shaped portion 8a of the support 8, and since the plate-shaped portion 8a has a length approximately equal to the axial length of the unit cell 1 and a wide cross section, this plate The current density in the shaped portion 8a does not become particularly high, and the current from a given stack 2 to another stack 2 does not pass through one end of each stack 2 in the axial direction. Since the current flows directly from any location through the plate-shaped plate 1g8a, the current flow path between the stacks 2 becomes short. Therefore, the resistance caused by connecting the stack 2 does not become particularly large, resulting in a high output fuel cell.

In addition, in the present invention, the stacks 2 are not only connected in series as described in the above embodiments, but also stack groups connected in series as described above may be connected in parallel with each other.

Effects of the Invention As is clear from the above explanation, the fuel cell of this invention has four advantages.
According to No. 11, a conductive support that holds a plurality of single cells connected in parallel has the function of a connector that electrically connects the half-cell groups, and also has the function of disconnecting the electrical circuit. The area becomes wider, and the electric path is not located unevenly at one end in the axial direction, but exists throughout the entire axial direction, and as a result, the electric path length between the unit cell groups becomes shorter,
Therefore, according to the present invention, a high output fuel cell with low internal resistance and low internal loss can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional front view showing a part of an embodiment of the present invention;
FIG. 2 is a cross-sectional view schematically showing one of the unit cells, and FIG. 3 is a partially omitted perspective view showing its support. DESCRIPTION OF SYMBOLS 1... Single cell, 2... Stack, 4... R elementary electrode, 5... Interconnector, 6... Solid electrolyte, 7... Fuel electrode, 8... Support, 8a・
... Plate-shaped part, 8b... Slit, 8C... Cylindrical part.

Claims (1)

[Claims] A conductive support body consisting of a cylindrical part in which a slit is formed along the axial direction, and a plate-shaped part that protrudes in the radial direction from the outer surface of the cylindrical part and is thinner than the width of the slit; A plurality of single cells having electrodes electrically connected to the plate-like part are arranged to surround the tip of the plate-like part, and these single cells are housed in a cylindrical part of another conductive support. ,
A structure of a solid electrolyte fuel cell characterized in that the other electrode of each unit cell is electrically connected to the cylindrical part.