JP2769629B2 - Cylindrical solid electrolyte fuel cell - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plurality of cells arranged around an internal current collector to form a stack, or a plurality of stacks arranged around an internal current collector to form a module. The present invention relates to a cylindrical solid electrolyte fuel cell configured as described above.

2. Description of the Related Art As is well known, a solid electrolyte fuel cell has an oxygen electrode made of a perovskite-type composite oxide or the like sandwiched between a solid electrolyte having oxygen ion permeability such as yttria-stabilized zirconia (YSZ) and Ni or Ni-ZrO. _A fuel cell composed of _two cermets or the like is provided to constitute a unit cell, a plurality of the unit cells are connected in series or parallel to form a stack, and a plurality of the stacks are assembled to form a module. The required output is obtained by connecting a large number of cells as described above. Conventionally, cylindrical cells and flat monolithic cells have been known as such cells or stacks.However, the ease of sealing between an oxidizing gas such as air and a fuel gas such as hydrogen gas and the ease of manufacturing are known. The cylindrical type is superior in terms of easiness and the like.

FIG. 4 is a cross-sectional view showing an example of a stack constituting a cylindrical fuel cell, and FIG. 5 is a cross-sectional view showing one of the unit cells. The stack 1 is made of a conductive material such as Ni. A plurality (6 in the figure)
), And the outer periphery thereof is covered with a cylindrical external current collector 4 made of a conductive material such as Ni. Here, as shown in FIG. 5, the single cell 3 has an oxygen electrode 6 formed on the outer periphery of a ceramic support tube 5 formed in a porous structure with alumina (Al ₂ O ₃ ) or the like.
An interconnector 7 electrically connected to the fuel cell 9 is provided so as to protrude in the radial direction, a solid electrolyte 8 is provided on the outer periphery of the oxygen electrode 6, and a non-conductive fuel electrode 9 is provided on the outer periphery of the solid electrolyte 8 on the interconnector 7. ing. The unit cells 3 are electrically connected to the internal current collector 2 with a conductive felt 10 such as Ni felt interposed at the tip of the interconnector 7, and the fuel cell 9 of each unit cell 3 is made of a conductive felt.
It conducts to the external current collector 4 through 11. In addition, the reason why the conductive felts 10 and 11 are interposed is that the current collectors 2 and 4 and the interconnect 7 are rigid bodies having no elasticity, and the thermal expansion coefficients of the respective components are not the same. This is because it is necessary to ensure thermal expansion at the same time.

Problems to be Solved by the Invention By the way, the voltage obtained from the above-mentioned unit cells 3 is 1 volt or less, and the current density is about 100 to 300 mA. They must be connected in parallel, and accordingly, the resistance at the connection point or the quality of the connection greatly affects the power generation capacity. However, in the fuel cell having the above-described structure, since the internal current collector 2 and the external current collector 4 are substantially rigid bodies, each cell 3
And the current collectors 2 and 4 to ensure a conductive state, but the filling amount and filling method of the conductive felts 10 and 11 must depend on the amount and method predetermined in design. If there is a deviation in the arrangement of the cells 3 or a dimensional error in the cells 3 or the current collectors 2 and 4, the contact state via the conductive felts 10 and 11 becomes non-uniform or partially Insufficient. Therefore, in the above-described structure of the fuel cell, the resistance at the connection between the unit cell 3 and the current collectors 2 and 4 or when the unit cells 3 are connected in series increases the resistance at the connection part between the unit cells 3 and sufficient power generation. There was a possibility that efficiency could not be obtained.

The present invention has been made in view of the above circumstances, and provides a cylindrical solid electrolyte fuel cell that can reliably connect cells or stacks or between them and a current collector, thereby improving power generation efficiency. The purpose is to do so.

Means for Solving the Problems In order to achieve the above object, the present invention provides a plurality of power generating elements which generate an electromotive force due to a difference in oxygen concentration between the inner and outer circumferences of a cylindrical solid electrolyte having oxygen ion permeability. Are arranged on the outer peripheral side of the internal current collector, and the power generating elements are bound by a conductive tape wound around the outer peripheral side.

Further, in the present invention, a conductive felt may be used, in which case, the conductive felt may be interposed between at least one of between the internal current collector and the power generation element and between the power generation element and the conductive tape. it can.

Here, the power generation element includes not only a unit cell but also a stack formed by forming a plurality of unit cells on the outer periphery of a support tube, a stack formed by binding a plurality of unit cells, and a unit formed by binding a plurality of stacks. Including modules.

In the fuel cell according to the present invention, an oxidizing gas containing oxygen gas and a fuel gas such as hydrogen gas flow on both sides of the solid electrolyte, thereby generating an electromotive force due to a difference in oxygen concentration between the inside and the outside of the solid electrolyte. Is generated, and the electromotive force in each power generation element is output from the internal current collector and the conductive tape on the outer peripheral side. Since each power generating element is arranged on the outer periphery of the internal current collector and is bound by a conductive tape in that state, each power generating element is securely brought into close contact with the internal current collector by the tension at the time of winding the conductive tape. At the same time, the conductive tape is securely adhered to the conductive tape. As a result, the contact state of each power generation element with the conductive tape serving as the internal current collector and the external current collector becomes good, and the resistance at these connection portions is reduced, thereby improving the power generation efficiency.

In the case where a conductive felt is interposed, a large contact area is ensured even when the inner surface of the current collector or the power generating element has irregularities, and the electrical connection state is improved.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing one embodiment of the present invention,
The example shown here is an example of a fuel cell in which six unit cells 3 are equally arranged on the outer periphery of the internal current collector 2 to form a stack 20, and the unit cell 3 is the one described with reference to FIG. Since the configuration is the same as that described above, the description is omitted here. The internal current collector 2 is formed in a cylindrical shape from a material having a high melting point and a resistance to hydrogen embrittlement, such as Ni, a Ni alloy, and a cermet containing Ni. The conductive felt 21 is interposed between the interconnector 7 and the internal current collector 2 by, for example, winding the conductive felt 21 around the inner current collector 2. The conductive felt 21 may be Ni or
Those made of Ni alloy can be used. Then, a conductive tape 22 is wound around the outer periphery of these cells 3, and the cells 3 are bound around the internal current collector 2. The conductive tape 22 has a melting point equal to or higher than the operating temperature of the fuel cell (about 900 to 1200 ° C.). When a fuel gas is supplied to the outer peripheral surface of the unit cell 3, a tape having excellent hydrogen embrittlement resistance is used. Specifically, a tape made of Ni alloy such as Ni and Inconel is used. The conductive tape 22 is wound spirally as schematically shown in FIG. 2 while applying a tension that does not crush the cell 3. As a result, the interconnector 7 of each cell 3 is in close contact with the internal current collector 2 via the conductive felt 21 and, of course, also in close contact with the conductive tape 22.

Since the solid electrolyte 8 in each cell 3 shows excellent oxygen ion permeability at about 900 to 1200 ° C., the solid electrolyte 8 is heated to this temperature and the oxygen is applied to the inner periphery of each cell 3. An oxidizing gas containing gas is supplied, and each cell 3
A fuel gas such as a hydrogen gas is flown to the outer peripheral side of the fuel cell. Accordingly, an electromotive force is generated due to a difference in oxygen concentration between the inner and outer peripheries of the solid electrolyte 8.
Becomes the cathode. Therefore, the internal current collector 2 serves as an anode and the conductive tape 22 serves as a cathode as a whole of the stack 20. In this case, each unit cell 3 is fastened by the conductive tape 22 and closely adheres to the internal current collector 2 and the conductive tape 22 which is the external current collector, and the contact state is good. And as a result, the internal resistance of the fuel cell is reduced, so that high output is achieved.

In addition, the conductive felt 21 fills the unevenness of the outer peripheral surface of the internal current collector 2 and the tip end surface of the interconnector 7 to secure a large contact area, so that the contact state is also good and the internal resistance of the fuel cell is reduced. Is achieved.

When the entire stack 20 is heated and heated to the operating temperature of the fuel cell, the internal current collector 2 and the unit cells 3 thermally expand and the expansion amounts are different. It is absorbed by the elastic deformation, and the stress of the cell 3 and the internal current collector 2 is relaxed. Conversely, when heat shrinkage occurs due to a temperature drop, the internal taper 2 and the cell 3 and the conductive tape 22 maintain good contact with each other because the fastening force of the conductive tape 22 is acting. Is done.

The conductive felt 21 may be provided on the inner peripheral side of the conductive tape 22 as shown in FIG. 3 instead of being provided on the outer peripheral surface of the internal current collector 2. Since the conductive felt 21 fills 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 the amount of thermal expansion and, at the same time, substantially separates the unit cell 3 from the conductive tape 22. Enlarge the effective contact area.

Further, in the above embodiment, an example was described in which cylindrical unit cells were arranged on the outer periphery of the internal current collector and bound, but a number of unit cells were connected in series to each other on the outer peripheral surface of the porous support tube. The present stack also has a cylindrical shape and needs to be connected in parallel. Therefore, the present invention relates to a case where such a stack is connected in parallel via an internal current collector as shown in FIG. 1 or FIG. Can also be applied. Further, the present invention can be applied to a case where a plurality of stacks shown in FIG. 1 or FIG.

Advantageous Effects of the Invention As is apparent from the above description, according to the fuel cell of the present invention, a plurality of power generation elements arranged on the outer peripheral side of the internal current collector are bound by the conductive tape wound around the outer periphery thereof. The elements are clamped toward the internal current collector, and as a result, the state of contact between the power generating element and the internal current collector and the state of contact between the power generating element and the conductive tape serving as the external current collector are well maintained. , The internal resistance of the fuel cell is reduced, the power generation efficiency is improved, and a higher output can be achieved. Further, according to the present invention, since the conductive tape binding the plurality of power generating elements serves as the external current collector, the manufacturing operation of the internal current collector, the power generating elements arranged on the outer periphery thereof, and the structure including the external current collector is performed. The performance is improved. Furthermore, since ceramics are often used for the power generating element, if a conductive felt is interposed in the contact portion, it is possible to fill the unevenness on the surface of the power generating element and secure a wide contact area.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a partial side view showing a state of winding a conductive tape, FIG. 3 is a sectional view showing another embodiment, and FIG. FIG. 5 is a sectional view showing an example of a unit cell. 2 ... internal current collector, 3 ... unit cell, 6 ... oxygen electrode, 7
... interconnector, 8 ... solid electrolyte, 9 ... fuel electrode, 20 ... stack, 21 ... conductive felt, 22 ...
Conductive tape.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Tan 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (72) Inventor Hiroshi Yamanouchi 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire (72) Inventor Masakatsu Nagata 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (56) References JP-A-58-175267 (JP, A) (58) Fields investigated (Int .Cl. ⁶ , DB name) H01M 8/00-8/02 H01M 8/08-8/24

Claims (2)

(57) [Claims] A plurality of power generating elements that generate an electromotive force due to a difference in oxygen concentration between the inner and outer circumferences of a cylindrical solid electrolyte having oxygen ion permeability are arranged on an outer circumferential side of an internal current collector, and the power generating elements are generated. A cylindrical solid electrolyte fuel cell, wherein the elements are bound by a conductive tape wound around the outer periphery thereof. 2. A conductive felt is interposed 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 claim 1.