A fuel cell stack includes: a separator comprising channels and lands alternately repeated; and a gas diffusion layer in contact with the separator for transferring gas to a membrane-electrode assembly. The gas diffusion layer has a fiber arrangement structure having a predetermined directionality beneath the lands adjacent to opposite lateral sides of the channels based on a central portion of the channels to guide a transfer passage of the gas.

A fuel cell stack includes: a separator comprising channels and lands alternately repeated; and a gas diffusion layer in contact with the separator for transferring gas to a membrane-electrode assembly. The gas diffusion layer has a fiber arrangement structure having a predetermined directionality beneath the lands adjacent to opposite lateral sides of the channels based on a central portion of the channels to guide a transfer passage of the gas.

In order to provide a membrane electrode assembly that can further improve power generation performances of a fuel cell, the present invention allows a rib portion (22) that separates mutually adjacent gas flow passages (21) from each other to have a porosity lower than the porosity of a lower area (23) of the rib portion. Thus, it is possible to suppress the deformation of the rib portion and excessive permeation of a reaction gas, and consequently to further improve the power generation performances.

A gas diffusion layer (30) for a fuel cell includes: a gas diffusion layer substrate (31); and a microporous layer (32) containing a granular carbon material and scale-like graphite and formed on the gas diffusion layer substrate (31). The microporous layer (32) includes a concentrated region (32a) of the scale-like graphite that is formed into a belt-like shape extending in a direction approximately parallel to a junction surface (31a) between the microporous layer (32) and the gas diffusion layer substrate (31). Accordingly, both resistance to dry-out and resistance to flooding, which are generally in a trade-off relationship, in the gas diffusion layer can be ensured so as to contribute to an increase in performance of a polymer electrolyte fuel cell.

A gas diffusion layer (30) for a fuel cell includes: a gas diffusion layer substrate (31); and a microporous layer (32) containing a granular carbon material and scale-like graphite and formed on the gas diffusion layer substrate (31). The microporous layer (32) includes a concentrated region (32a) of the scale-like graphite that is formed into a belt-like shape extending in a direction approximately parallel to a junction surface (31a) between the microporous layer (32) and the gas diffusion layer substrate (31). Accordingly, both resistance to dry-out and resistance to flooding, which are generally in a trade-off relationship, in the gas diffusion layer can be ensured so as to contribute to an increase in performance of a polymer electrolyte fuel cell.

A gas diffusion layer having a first major surface and a second major surface which is positioned opposite to said first major surface and an interior between said first and second major surfaces is formed. The gas diffusion layer comprises a porous carbon substrate which is directly fluorinated in the interior and is substantially free of fluorination on at least one of the first major surfaces or the second major surfaces, and preferably both surfaces. The gas diffusion layer may be formed using protective sandwich process during direct fluorination or by physically or chemically removing the C—F atomic layer at the major surfaces, for example by physical plasma etching or chemical reactive ion etching.

A gas diffusion layer having a first major surface and a second major surface which is positioned opposite to said first major surface and an interior between said first and second major surfaces is formed. The gas diffusion layer comprises a porous carbon substrate which is directly fluorinated in the interior and is substantially free of fluorination on at least one of the first major surfaces or the second major surfaces, and preferably both surfaces. The gas diffusion layer may be formed using protective sandwich process during direct fluorination or by physically or chemically removing the C—F atomic layer at the major surfaces, for example by physical plasma etching or chemical reactive ion etching.

A fuel cell gas supply and diffusion layer includes a sheet-like porous body layer, and a plurality of gas passage grooves formed on one surface of the porous body layer in parallel and formed in a zigzag shape or a wave shape respectively. As viewed in a plan view, a first rectangular region where circumscribes one gas passage groove and a second rectangular region where circumscribes a gas passage groove adjacent to the one gas passage groove overlap along a region in contact each other. An overlapping region where the first rectangular region and the second rectangular region overlap exists at any depth position of the grooves. According to the fuel cell gas supply and diffusion layer, it is possible to increase a power generation efficiency of a fuel cell.

A fuel cell gas supply and diffusion layer includes a sheet-like porous body layer, and a plurality of gas passage grooves formed on one surface of the porous body layer in parallel and formed in a zigzag shape or a wave shape respectively. As viewed in a plan view, a first rectangular region where circumscribes one gas passage groove and a second rectangular region where circumscribes a gas passage groove adjacent to the one gas passage groove overlap along a region in contact each other. An overlapping region where the first rectangular region and the second rectangular region overlap exists at any depth position of the grooves. According to the fuel cell gas supply and diffusion layer, it is possible to increase a power generation efficiency of a fuel cell.

Electrochemical cells can include flow channels designed to provide an electrolyte solution more efficiently to an electrode or ionically conductive separator. Such electrochemical cells can include an ionically conductive separator disposed between a first half-cell and a second half-cell, a first bipolar plate in the first half-cell, and a second bipolar plate in the second half-cell. At least one of the first bipolar plate and the second bipolar plate are a composite containing a conductive material and a blocking material. The blocking material defines a plurality of flow channels that are spaced apart from one another and extend laterally through the composite with respect to the ionically conductive separator. The plurality of flow channels are also in fluid communication with one another in the composite. Such electrochemical cells can be incorporated in electrochemical stacks and/or be fluidly connected to a fluid inlet manifold and a fluid outlet manifold.