JPH02299168A - Cylindrical solid electrolyte fuel cell - Google Patents

Abstract

PURPOSE:To ensure the connection between unit cells and stacks or between them and current collectors and to improve the power generating efficiency by binding power generating elements with a conducting tape wound on the outside. CONSTITUTION:Power generating elements are arranged around inner current collectors 2 and bound by a conducting tape 22 under this condition, thus the power generating elements are surely stuck to the inner current collectors 2 by the tensile force of the conducting tape 22 when it is wound, and they are also closely stuck to the conducting tape 22. As a result, the contact state of the power generating elements with the inner current collectors and the conducting tape serving as an outer current collector is improved, the resistance at these connection portions is reduced, and the power generating efficiency is improved. When a conducting felt 21 is inserted either between the outer peripheries of the inner current collectors and the power generating elements or between the inner periphery of the conducting tape and the power generating elements, wide contact areas are secured even if outer faces of the inner current collectors and power generating elements have irregularities, and the electric contact state is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for forming a stack by arranging a plurality of single cells around an internal current collector, or by arranging a plurality of stacks around an internal current collector to form a module. The present invention relates to the constructed cylindrical solid electrolyte fuel cell.

As is well known in the art, a solid electrolyte fuel cell consists of an oxygen electrode made of a velorskite composite oxide, etc., and a Ni or A fuel electrode made of Ni-2r02 cermet or the like is provided to form a single cell, a plurality of these single cells are connected in series or parallel to form a stack, and multiple stacks are combined to form a module. The required output is obtained by connecting a large number of single cells in this way. Hitherto, cylindrical and flat monolithic cells or stacks have been known as this type of unit cell or stack, but they are difficult to manufacture due to ease of sealing between oxidizing gas such as air and fuel gas such as hydrogen gas. A cylindrical type is superior in terms of ease of use.

FIG. 4 is a cross-sectional view showing an example of a stack constituting a cylindrical fuel cell, and FIG. A structure in which a plurality of cells 3 (six in the figure) are arranged around the outer periphery of a cylindrical internal current collector 2, and the outer periphery is further covered with a cylindrical external current collector 4 made of a conductive material such as Ni. It becomes. Here, as shown in FIG. 5, the cell 3 has an M elementary electrode 6 formed on the outer periphery of a ceramic support tube 5 made of alumina (^i!203) or the like with a porous structure, and is electrically connected to the oxygen electrode 6. A solid electrolyte 8 is provided on the outer periphery of the oxygen electrode 6.
The interconnector 7 is further provided with a non-conducting fuel electrode 9 on the outer periphery of the solid electrolyte 8.

This unit cell 3 has an internal current collector 2 by interposing a conductive felt 10 such as Ni felt at the tip of an interconnector 7.
The fuel cell 9 of each unit cell 3 is electrically connected to the external current collector 4 via a conductive felt 11. The reason why the conductive felts io and 1i are interposed is that the current collectors 2, 4 and the interconnect 7 are rigid bodies with no elasticity, and the thermal expansion coefficients of the respective constituent members are not the same. This is because it is necessary to absorb thermal expansion while ensuring reliability.

Problems to be Solved by the Invention By the way, the voltage obtained with the above-mentioned unit cell 3 is 1 volt or less, and the current density is about 100 to 30 QmA, so it is necessary to use a large number of 1$ batteries 3 to obtain the necessary power.
must be connected in series and parallel, and the resistance at the connection point or the quality of the connection will greatly affect the power generation capacity.

However, in the fuel cell configured as described above, since the internal current collector 2 and the external current collector 4 are substantially rigid bodies, each unit cell 3 and each current collector 2, 4 are separated by the cushioning properties of the conductive felt 10. However, since the amount and method of filling the conductive felts 10 and 11 must be determined in advance by the design,
If there is a deviation in the arrangement or a dimensional error in the cell 3 or each current collector 2, 4, the contact state through the conductive felt 10.11 will become uneven or partially insufficient. . Therefore, in the structure of the fuel cell described above, the single cell 3
When connecting the battery and the collectors 2 and 4, or when the cells 3 were connected in series, there was a possibility that the resistance at the connection between the cells 3 would increase and sufficient power generation efficiency could not be obtained. .

This invention has been made in view of the above circumstances, and provides a cylindrical solid electrolyte fuel cell that can securely connect single cells or stacks to each other or to a current collector, thereby improving power generation efficiency. The purpose is to

Means for Solving the Problems In order to achieve the above object, the present invention provides a plurality of power generation elements that generate an electromotive force due to the difference in oxygen concentration between the inner and outer circumferential sides of a cylindrical solid electrolyte that is permeable to oxygen ions. are arranged on the outer periphery of the internal current collector, and the power generating elements are bound together with a conductive tape wrapped around the outer periphery.

In addition, in this invention, conductive felt can also be used,
In that case, the conductive felt can be interposed between the internal current collector and the power generation element, or between the power generation element and the conductive tape.

Here, the power generation element includes not only single cells but also a stack formed by forming a plurality of IIi cells around the outer periphery of a support tube, a stack formed by bundling a plurality of cell cells, and a stack formed by bundling a plurality of stacks. Including modules etc.

Function: In the fuel cell of the present invention, by flowing an oxidizing gas containing oxygen gas and a fuel gas such as hydrogen gas on both sides of the solid electrolyte, it is possible to eliminate the problem caused by the difference in oxygen concentration between the inside and outside of the solid electrolyte. Electric power is generated, and the electromotive force in each power generating element is output from the internal current collector and the conductive tape on the outer circumferential side. Each power generating element is arranged around the outer periphery of the internal current collector and bound together with conductive tape, so that the winding of the conductive tape ensures that each power generating element is firmly attached to the internal current collector due to the tension of the conductive tape. It also adheres reliably to conductive tape when exposed. As a result, the contact state of each power generation element with the 11-conductor tape serving as an internal current collector and an external current collector becomes good, and the resistance at these connection parts is reduced, thereby improving photoelectric efficiency.

Further, when a conductive felt is interposed, a wide contact area is ensured even if the internal current collector or the outer surface of the power generation element is uneven, and a good electrical connection is achieved.

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

FIG. 1 is a sectional view showing one embodiment of the present invention, and the example shown here is an example of a fuel cell in which six unit cells 3 are equally distributed around the outer circumference of an internal current collector 2 to form a stack 20. Since the unit cell 3 has the same structure as that explained with reference to FIG. 5, the explanation thereof will be omitted here. internal fa
Electron 2 is formed into a cylindrical shape from a material with a high melting point and hydrogen embrittlement resistance, such as Ni, Ni alloy, or cermet containing Ni, and is 6I! The unit cell 3 of I is arranged with its interconnector 7 facing the internal current collector 2, and is connected between the interconnector 7 and the internal current collector 2 by means such as wrapping a quadrielectric felt 21 around the outer periphery of the internal current collector 2. A conductive felt 21 is interposed between them.

Note that the conductive felt 21 may be made of Ni or a Ni alloy. And these batteries 3
A 3# electrical tape 22 is wrapped around the outer periphery of the cell 3, and each cell 3 is bundled around the internal current collector 2. This conductive tape 22 is heated at the operating temperature of the fuel cell (900 to 1200°C).
When flowing fuel gas to the outer periphery of the unit cell 3, a material with excellent hydrogen embrittlement resistance is used; specifically, it is made of a Ni alloy such as NiNinconel, etc. tape is used. This conductive tape 22
is applied to the second cell while applying tension to an extent that does not crush the cell 3.
It is wound in a spiral as shown schematically in the figure. As a result, the interconnector 7 of each cell 3 is in close contact with the internal current collector 2 via the quadrielectric felt 21, and of course also with the conductive tape 22.

The temperature of the solid electrolyte 8 in each cell 3 is 900 to 1200°C
Since the solid electrolyte 8 is heated to a temperature of this level, an oxidizing gas containing oxygen gas is flowed around the inner circumference of each unit cell 3, and each unit cell is heated to a temperature of this level. Fuel gas such as hydrogen gas is flowed around the outer circumferential side of 3. Accordingly, an electromotive force is generated due to the difference in oxygen concentration between the inner and outer peripheries of the solid electrolyte 8, and in each unit cell 3, the oxygen electrode 6 serves as an anode and the fuel electrode 9 serves as a cathode. Therefore, for the stack 2o as a whole, the internal current collector 2 serves as an anode, and the conductive tape 22 serves as a cathode. In that case, each cell 3 is tightened by the 4-conductor tape 22 and comes into close contact with the internal current collector 2 and the external current collector conductive tape 22, and the contact state is good, so that Since the resistance is small, and as a result, the internal resistance of the fuel cell is reduced, high output can be achieved.

In addition, the conductive felt 21 fills in the irregularities on the outer circumferential surface of the internal current collector 2 and the tip end surface of the interconnector 7 to ensure a wide contact area, so the contact condition is good in this respect as well, and the internal resistance of the fuel cell is reduced. will be promoted.

When the entire stack 20 is heated to the operating temperature of the fuel cell, the internal current collector 2 and the single cells 3 undergo thermal expansion, and the amount of expansion is different. It is absorbed by elastic deformation, and the stress in the cell 3 and internal current collector 2 is relaxed. On the other hand, if thermal contraction occurs due to a temperature drop, the conductive tape 22
Since force is applied during the tightening, the state of contact between the internal current collector 2, the cell 3, and the conductive tape 22 is maintained well.

In addition, instead of providing the conductive felt 21 on the outer peripheral surface of the internal current collector 2, it may be provided on the inner peripheral side of the conductive tape 22 as shown in FIG. Since the conductive felt 21 fills in the irregularities on the outer surface of the battery 3, that is, the outer surface of the fuel electrode 9, the conductive felt 21 absorbs the difference in thermal expansion and at the same time, the substantial difference between the unit cell 3 and the conductive tape 22. Expand the contact area.

In addition, in the above embodiment, an example was explained in which cylindrical cells were arranged around the outer periphery of the internal current collector and bundled. Stacks made of these materials also have a cylindrical shape and need to be connected in parallel. Therefore, the present invention is applicable to the case where such stacks are connected in parallel via internal current collectors as shown in FIG. 1 or 2. can also be applied. Furthermore, the present invention can be applied to the case where a plurality of stacks shown in FIG. 1 or 3 are combined into a module.

Effects of the Invention As is clear from the above explanation, according to the fuel cell of the present invention, the plurality of power generation elements arranged on the outer circumference side of the internal current collector are bound by the conductive tape wrapped around the outer circumference, so that each power generation element is The element is tightened toward the internal current collector, and as a result, good contact is maintained between the power generating element and the internal current collector, and between the power generating element and the conductive tape serving as the external current collector, and in these parts. This improves the conduction state of the fuel cell, reduces the internal resistance of the fuel cell, and improves power generation efficiency, making it possible to achieve high output.

Further, according to the present invention, since the conductive tape that binds a plurality of power generating elements serves as an external current collector, manufacturing work for a structure consisting of an internal current collector, a plurality of power generating elements arranged around the outer periphery of the internal current collector, and an external current collector is performed. Improves sex. Since ceramics are often used for power generation elements, by interposing conductive felt in the contact area, it is possible to fill in the irregularities on the surface of the power generation element and ensure a wide contact area.

[Brief Description of the Drawings] Fig. 1 is a sectional view showing one embodiment of the present invention, Fig. 2 is a partial side view showing the state of winding of the conductive tape, and Fig. 3 shows another embodiment. 4 is a sectional view showing an example of a conventional stack, and FIG. 5 is a sectional view showing an example of a single cell. 2... Internal current collector, 3... Cell, 6... Oxygen electrode, 7... Interconnector, 8... Solid electrolyte, 9... Fuel electrode, 20... Stack,
21... Conductive felt, 22... Conductive tape.

Claims (2)

[Claims] (1) A plurality of power generation elements that generate electromotive force due to the difference in oxygen concentration between the inner and outer circumferences of a cylindrical solid electrolyte that is permeable to oxygen ions are arranged on the outer circumference side of the internal current collector, and these power generation elements are arranged on the outer circumference side of the internal current collector. A cylindrical solid electrolyte fuel cell characterized in that elements are bound together with conductive tape wrapped around the outer periphery of the elements. (2) A claim characterized in that a conductive felt is interposed either between the outer peripheral surface of the internal current collector and the power generating element or between the inner peripheral surface of the conductive tape and the power generating element. The cylindrical solid electrolyte fuel cell according to item 1.