Abstract: The present invention provides a fuel stack comprising: a plurality of fuel cell units stacked together in a direction of stacking each of which comprises an electrolyte element, a pair of electrodes holding the electrolyte element therebetween, and a pair of separators holding the electrodes therebetween; a pair of terminal plates each of which is disposed outside an end fuel cell unit located at an end of the stacked fuel cell units; and a terminal element extending outwardly in the direction of stacking from the outside surface of at least one of the terminal plates; wherein the location from which the terminal element extends is located within an area on the terminal plate, corresponding to an area in a passage for an oxidizing gas formed in the end fuel cell unit disposed adjacent to the terminal element where the partial pressure of water vapor is lower than the saturated water vapor pressure.

Abstract: The present invention provides a fuel stack comprising: a plurality of fuel cell units stacked together in a direction of stacking each of which comprises an electrolyte element, a pair of electrodes holding the electrolyte element therebetween, and a pair of separators holding the electrodes therebetween; a pair of terminal plates each of which is disposed outside an end fuel cell unit located at an end of the stacked fuel cell units; and a terminal element extending outwardly in the direction of stacking from the outside surface of at least one of the terminal plates; wherein the location from which the terminal element extends is located within an area on the terminal plate, corresponding to an area in a passage for an oxidizing gas formed in the end fuel cell unit disposed adjacent to the terminal element where the partial pressure of water vapor is lower than the saturated water vapor pressure.

Abstract: First gas flow passage grooves communicating with a fuel gas inlet and second gas flow passage grooves communicating with a fuel gas outlet are provided on a surface of a first separator. First and second united sections are provided at merged portions of the first gas flow passage grooves and the second gas flow passage grooves. Accordingly, the number of gas flow passage grooves is throttled from the side of the fuel gas inlet to the side of the fuel gas outlet. The turbulence is allowed to occur at the throttled portion to make it possible to improve the gas diffusion performance.

Abstract: A fuel cell stack comprises first and second separators for holding a fuel cell unit therebetween. The first separator has a fuel gas flow passage and the second separator has an oxygen-containing gas flow passage. The gas flow passages are formed by grooves with the number of grooves decreasing from the inlet to the outlet. In one embodiment, the gas flow passage comprises twelve individual first gas flow passage grooves which communicate with an inlet hole on a gas inlet side, six individual second gas flow passage grooves which communicate with the first gas flow passage grooves, and three individual third gas flow passage grooves which communicate with the second gas flow passage grooves. The third gas flow passage grooves communicate with an outlet hole on a gas outlet side.