Patent ID: 8034506

Claim:
A fuel cell formed by stacking a membrane electrode assembly and a separator in a horizontal stacking direction, said membrane electrode assembly including a pair of electrodes and an electrolyte membrane interposed between said electrodes, said separator having a rectangular shape including long sides extending in the direction of gravity and short sides extending horizontally in a direction perpendicular to the stacking direction, said separator having a reactant gas flow field for supplying a reactant gas along an electrode surface in the direction of gravity, wherein an inlet buffer is provided above the reactant gas flow field and an outlet buffer is provided below the reactant gas flow field, the inlet buffer and the outlet buffer extend along an entire width of the reactant gas flow field; a reactant gas supply passage for supplying the reactant gas to said reactant gas flow field and a reactant gas discharge passage for discharging the reactant gas from the reactant gas flow field extend through said separator in the stacking direction; a lower edge of said outlet buffer includes a first inclined surface extending downward from one end of the lower edge and a second inclined surface extending downward from another end of the lower edge; said reactant gas discharge passage is positioned below said outlet buffer, the first inclined surface is connected to the reactant gas discharge passage through an outlet channel portion, and the first inclined surface is parallel to an inclined surface of said reactant gas discharge passage; said reactant gas flow field extends in the direction of gravity; and the reactant gas flows continuously downward from an upper end to a lower end of the reactant gas flow field along the direction of gravity.