TECHNICAL FIELD

The present invention relates to a fuel cell including a membrane electrode assembly formed by providing a plurality of anodes and a plurality of cathodes for one electrolyte membrane.

BACKGROUND ART

A typical fuel cell is formed by stacking a plurality of unit cells together. Each of the unit cells is obtained by sandwiching a membrane electrode assembly (MEA) between a pair of separators. This structure is known as a fuel cell stack. In contrast, in recent years, it is proposed to provide a plurality of anodes and a plurality of cathodes for one electrolyte electrode assembly to form a plurality of unit cells having a planar shape.

As described in Japanese Laid-Open Patent Publication No. 2011-204609, in this case, interconnecting sections are formed in the electrolyte membrane for electrically connecting the adjacent unit cells together. That is, a plurality of unit cells are connected in series through the interconnecting sections. In the case of adopting the structure, a high voltage fuel cell can be obtained using one electrolyte membrane, and no operation of stacking the unit cells together is required advantageously.

SUMMARY OF INVENTION

The electrolyte membrane is a thin membrane, and soft enough to be warped when the electrolyte membrane is held by an operator, by a clamp, etc. Therefore, there is a potential inconvenience where it is not easy to transport the electrolyte membrane, and/or insert the electrolyte membrane between the oxygen-containing gas supply layer and the fuel gas supply layer, i.e., it is not easy to handle the electrolyte membrane in general.

A main object of the present invention is to provide a fuel cell having a membrane electrode assembly which can be handled easily.

Another object of the present invention is to provide a fuel cell which can be assembled easily, for example.

According to an embodiment of the present invention, a fuel cell is provided. The fuel cell includes a membrane electrode assembly including a single electrolyte membrane in which interconnecting sections are formed, the interconnecting sections extending in a first direction and having conductivity in a membrane thickness direction of the electrolyte membrane, a plurality of anodes extending in the first direction, and disposed remotely from each other in a second direction perpendicular to the first direction, and a plurality of cathodes extending in the first direction, and disposed remotely from each other in the second direction, wherein the membrane electrode assembly has a zigzag layout where, in the second direction, part of one of the anodes faces part of one of two cathodes that are adjacent to each other, among the cathodes, through the electrolyte membrane and another part of the one anode faces part of the remaining one of the two cathodes through one of the interconnecting sections formed in the electrolyte membrane, the fuel cell further includes an anode side porous film configured to cover the plurality of anodes, the anode side porous film having breathing holes for supplying a fuel gas to the plurality of anodes, and a cathode side porous film configured to cover the plurality of cathodes, the cathode side porous film having breathing holes for supplying an oxygen-containing gas to the plurality of cathodes, and wherein an end of the anode side porous film and an end of the cathode side porous film are joined together in a manner that the membrane electrode assembly is enclosed inside the anode side porous film and the cathode side porous film.

After all, in the present invention, the membrane electrode assembly is enclosed inside a laminate layer provided by joining the anode side porous film and the cathode side porous film together. By this laminate layer, some extent of the rigidity is offered for the membrane electrode assembly (i.e., the membrane electrode assembly becomes so-called rigid). That is, the membrane electrode assembly becomes a hard elastic body to the extent that the membrane electrode assembly is not warped by its own weight.

Therefore, it is possible to handle the membrane electrode assembly easily. For example, it becomes easy to perform operation of holding and transporting the membrane electrode assembly, and perform operation of inserting the membrane electrode assembly between the oxygen-containing gas supply layer and the fuel gas supply layer. Thus, it becomes easy to assemble the fuel cell.

Additionally, by enclosing the membrane electrode assembly inside the laminate layer, the shape of the membrane electrode assembly is maintained. That is, it is possible to suppress deformation such as warpage of the membrane electrode assembly.

Preferably, a thickness of the anode side porous film is larger than a thickness of the cathode side porous film.

Preferably, the anode side porous film includes a plurality of first straight segments superimposed on the interconnecting sections and extending in a first direction, and a second straight segment intersecting with the plurality of first straight segments.

In the anode side porous film, openings surrounded by the first straight segments and the second straight segment are formed. The openings serve as breathing holes for supplying the fuel gas to the anodes covered with the anode side porous film. Further, the water produced in the electrode reactions is discharged through the breathing holes. That is, since the anode side porous film is present, some volume of the produced water is stored in the anode side porous film. Accordingly, since excessive drying of the anodes and the electrolyte membrane is avoided, the proton conductivity of the electrolyte membrane becomes suitable.

In the above structure, preferably, the anode side porous film and the cathode side porous film are configured to press the interconnecting sections. In this case, the contact resistance between the interconnecting sections and the anodes or the cathodes is reduced, and electrons are transmitted easily from the interconnecting sections to the cathodes. Therefore, since the internal resistance of the fuel cell is reduced, it is possible to obtain the fuel cell having a large electromotive force.

In the present invention, since the membrane electrode assembly is enclosed inside the laminate layer which is provided by joining the anode side porous film and the cathode porous film together, the membrane electrode assembly becomes hard to the extent that the membrane electrode assembly is not warped by its own weight. Thus, it is becomes easy to handle the membrane electrode assembly in general, e.g., perform operation of holding and transporting the membrane electrode assembly, and operation of inserting the membrane electrode assembly between the oxygen-containing gas supply layer and the fuel gas supply layer. Therefore, it becomes easy to assemble the fuel cell.

Further, warpage, etc. of the membrane electrode assembly enclosed inside the laminate layer does not occur easily. That is, it is possible to suppress deformation of the membrane electrode assembly.

