Fuel cell

Abstract

A power generation cell includes a membrane electrode assembly, and first and second separators sandwiching the membrane electrode assembly. The first separator includes an oxygen-containing gas flow field. An inlet buffer area is provided between the oxygen-containing gas flow field and an oxygen-containing gas supply passage, and an outlet buffer area is provided between the oxygen-containing gas flow field and an oxygen-containing gas discharge passage. Plural columnar resistance members are provided within the inlet buffer area and the outlet buffer area. The membrane electrode assembly further includes first and second humidification sections.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a fuel cell stack according to a first embodiment of the present invention;

FIG. 2 is an exploded perspective view showing a power generation cell of the fuel cell stack;

FIG. 3 is a partial enlarged cross sectional view showing the power generation cell;

FIG. 4 is a front view showing a second separator of the power generation cell;

FIG. 5 is a view showing the water vapor permeation state of the power generation cell;

FIG. 6 is a partial enlarged cross sectional view showing a power generation cell of a fuel cell stack according to a second embodiment of the present invention;

FIG. 7 is a partial enlarged view showing a first separator of a power generation cell of a fuel cell stack according to a third embodiment;

FIG. 8 is a partial cross sectional view illustrating the power generation cell of FIG. 7;

FIG. 9 is a partial enlarged view showing a power generation cell of a fuel cell stack according to a fourth embodiment of the present invention;

FIG. 10 is a partial cross sectional view illustrating the power generation cell of FIG. 9; and

FIG. 11 is a view showing a conventional fuel cell.

Claims

1. A fuel cell formed by stacking a membrane electrode assembly and a separator in a stacking direction, said membrane electrode assembly including a pair of electrodes and an electrolyte membrane interposed between said electrodes, a reactant gas passage for passing a reactant gas therethrough and extending through said separator in the stacking direction, said separator comprising:a reactant gas flow field formed at a position corresponding to a power generation area of said electrode for supplying the reactant gas to said electrode; anda buffer area provided between said reactant gas flow field and said reactant gas passage for stirring the reactant gas,said membrane electrode assembly comprising a humidification section facing said buffer area, wherein water permeates through said humidification section from said buffer area.

2. A fuel cell according to claim 1, wherein a resistance member is provided in said buffer area for providing resistance to the flow of said reactant gas.

3. A fuel cell according to claim 2, wherein said resistance member comprises a plurality of columnar resistance members.

4. A fuel cell according to claim 2, wherein said resistance member comprises a plurality of cylindrical protrusions.

5. A fuel cell according to claim 2, wherein said resistance member includes an inclined guide for guiding the reactant gas toward said membrane electrode assembly.

6. A fuel cell according to claim 5, wherein said resistance member comprises a plurality of pyramid shaped resistance members, and wherein each of said pyramid shaped resistance members includes an inclined surface, which is tapered toward said membrane electrode assembly, acting as said inclined guide.

7. A fuel cell according to claim 5, wherein said resistance member comprises a plurality of prismatic resistance members, and wherein each of said prismatic resistance members comprises a first inclined surface oriented along a flow direction of said reactant gas and acting as said inclined guide, and a second steeply inclined surface, positioned on an opposite side of said first inclined surface.

8. A fuel cell according to claim 1, wherein said electrode comprises an electrode catalyst layer and a gas diffusion layer, and wherein said humidification section comprises said gas diffusion layers only.