Polymer electrolyte fuel cell and fuel cell stack comprising the same

摘要

A polymer electrolyte fuel cell of the present invention comprises a membrane-electrode assembly (5), a first separator (6a), and a second separator (6b); the first separator (6a) having a groove-shaped first reaction gas channel (8) on one main surface of the first separator (6a) which contacts the first electrode (4a) such that a plurality of straight-line-shaped first rib portions (11) run along each other; the second electrode (4b) having a groove-shaped second reaction gas channel (9) on one main surface of the second electrode (4b) which contacts the second separator (6b) such that a plurality of straight-line-shaped second rib portions (12) run along each other; a ratio of a first reaction gas channel width of at least an upstream portion (18b) of the first reaction gas channel (8) with respect to a second rib portion (12) is greater than 0 and not greater than 1.

主权项

1. A polymer electrolyte fuel cell comprising:
a membrane-electrode assembly including a polymer electrolyte membrane and first and second electrodes sandwiching a pair of main surfaces of the polymer electrolyte membrane; an electrically-conductive first separator which is of a plate shape and is provided in contact with the first electrode of the membrane-electrode assembly; and an electrically-conductive second separator which is of a plate shape and is provided in contact with the second electrode of the membrane-electrode assembly, wherein: the first separator is provided with groove-shaped first reaction gas channels including a first reaction gas channel on one main surface of the first separator which contacts the first electrode such that a plurality of first rib portions of a straight-line shape run along each other, each of the plurality of first rib portions being located between adjacent two groove-shaped first reaction gas channels, the second electrode is provided with groove-shaped second reaction gas channels including a second reaction gas channel on one main surface of the second electrode which contacts the second separator such that a plurality of second rib portions of a straight-line shape run along each other, each of the plurality of second rib portions being located between adjacent two groove-shaped second reaction gas channels, an upstream portion of the first reaction gas channel is defined as a portion extending over a predetermined length from a portion which contacts the first electrode first from an upstream end of the first reaction gas channel toward a downstream side, a downstream portion of the first reaction gas channel is defined as a portion of the first reaction gas channel which is located downstream of the upstream portion of the first reaction gas channel, when a ratio of a first reaction gas channel width to the second rib portion is defined as a ratio of a portion of the first reaction gas channel which overlaps with the second rib portion in a width direction of the first reaction gas channel with respect to an overall width of the first reaction gas channel when viewed in a thickness direction of the first separator, a ratio of a first reaction gas channel width of at least the upstream portion of the first reaction gas channel with respect to the second rib portion is greater than 0 and not greater than 1, and the ratio of a first reaction gas channel width of the downstream portion of the first reaction gas channel with respect to the second rib portion is smaller than the ratio of a first reaction gas channel width of at least the upstream portion of the first reaction gas channel with respect to the second rib portion, the first reaction gas channel in the upstream portion is configured such that (i) the first reaction gas channel has a narrow portion in which a width of the first reaction gas channel in the upstream portion is smaller than a width of the first reaction gas channel in the downstream portion or (ii) the first reaction gas channel in the upstream portion is offset from the first reaction gas channel in the downstream portion, and the downstream portion of the first reaction gas channel includes a first constant portion in which the ratio of the first reaction gas channel width of the downstream portion of the first reaction gas channel with respect to the second rib portion is constant, the upstream portion of the first reaction gas channel includes a second constant portion in which the ratio of the first reaction gas channel width of at least the upstream portion of the first reaction gas channel with respect to the second rib portion is constant, and a ratio the first reaction gas channel width of the first reaction gas channel with respect to the second rib portion gradually changes between the first constant portion and the second constant portion.