A gas diffusion electrode includes a porous carbon electrode substrate and a microporous layer(s) provided at least on one surface of the porous carbon electrode substrate. The porous carbon electrode substrate is composed of carbon short fibers bonded with a resin carbide. When the region of the porous carbon electrode substrate, extending from a plane that has a 50% filling rate and is closest to one surface of the substrate to a plane that has the 50% filling rate and is closest to the other surface thereof, is trisected in the through-plane direction to obtain three layers, a layer located closer to one surface has a layer filling rate different from the layer filling rate of the layer located closer to the other surface. The microporous layer has a thickness under an added pressure of 0.15 MPa of from 28 to 45 m, and has a thickness under an added pressure of 2 MPa of from 25 to 35 m.

A description is given of a fuel cell comprising an electrode-membrane unit comprising a cathode and an anode, a cathodal gas diffusion element, an anodal gas diffusion element, the electrode-membrane unit being accommodated between the gas diffusion elements; a cathodal bipolar plate, and an anodal bipolar plate. Provision is made here for the cathodal gas diffusion element or/and the anodal gas diffusion element to have at least one structural element facing the respective bipolar plate and integrally bonded to the relevant gas diffusion element.

Disclosed are an electrode including a porous substrate, a membrane-electrode assembly for a fuel cell including the same and a method of manufacturing the same. In the method of manufacturing the membrane-electrode assembly, the amount of a catalyst that is loaded depending on the position is applied in a gradational manner, thus efficiently using the catalyst, thereby reducing costs owing to the use of a decreased amount of the metal catalyst. Further, the membrane-electrode assembly includes the electrode including a porous substrate, thus making it easy to select hot-pressing conditions and increasing processing efficiency. The porous substrate is hydrophobic and the pore size in the electrode is not decreased compared to conventional electrodes, thus reducing flooding and generating various operation regions. The electrode including the porous substrate can minimize electrode loss, thus improving electrode durability.

Electrochemical cells, such as those present within flow batteries, can have at least one electrode with a density gradient in which the density increases outwardly from a separator. Such electrodes can decrease contact resistance and lessen the incidence of parasitic reactions in the electrochemical cell. Flow batteries containing the electrochemical cells can include: a first half-cell containing a first electrode, a second half-cell containing a second electrode, and a separator disposed between the first half-cell and the second half-cell. At least one of the first electrode and the second electrode has a density gradient such that a density of at least one of the first electrode and the second electrode increases outwardly from the separator.

The purpose of the present invention is to provide a carbon sheet that is suitably employed in a gas-diffusion-electrode substrate that has excellent flooding resistance and with which it is possible to suppress internal peeling of the carbon sheet. In order to achieve the aforementioned purpose, the present invention has the following configuration. Specifically, provided is a porous carbon sheet containing carbon fibers and a binder, wherein, in a section between a surface on one side of the carbon sheet and a surface on the other side thereof, when layers obtained by dividing, under compression, the carbon sheet into six equal parts in the thickness direction are, assumed to be layer 1, layer 2, layer 3, layer 4, layer 5, and layer 6, in order starting from the layer including the surface on the one side to the layer including the surface on the other side, the layer in which the packing ratio under compression is the greatest is layer 2, and the relationships of the packing ratios under compression among layer 2, layer 3, layer 4, layer 5, and layer 6 are such that layer 2 has the greatest packing ratio, and layer 3 has the second-greatest packing ratio.

A reforming element for a molten carbonate fuel cell stack and corresponding methods are provided that can reduce or minimize temperature differences within the fuel cell stack when operating the fuel cell stack with enhanced CO.sub.2 utilization. The reforming element can include at least one surface with a reforming catalyst deposited on the surface. A difference between the minimum and maximum reforming catalyst density and/or activity on a first portion of the at least one surface can be 20% to 75%, with the highest catalyst densities and/or activities being in proximity to the side of the fuel cell stack corresponding to at least one of the anode inlet and the cathode inlet.

The invention relates to a membrane electrode assembly (15) for a fuel cell (10), comprising a membrane (11) on each side of which is disposed a catalytic layer (12, 13), and on this a gas diffusion layer (30).

It is provided that the gas diffusion layer (30) comprises a layer with electrically conductive particles (35), and a portion of the particles (35) is arranged directly adjacent to the catalytic layer (12, 13).

A fuel cell has a membrane electrode assembly including an electrolyte membrane, catalyst layers disposed on both sides of the electrolyte membrane, and three or more layers of porous bodies disposed on a front surface side of the catalyst layer, a frame body surrounding an outer periphery of the electrolyte membrane, and a separator that partitions and forms a gas passage between the membrane electrode assembly and the separator. Extended portions are provided at an outer edge of a first porous body adjacent to the separator among the three layers of the porous bodies, and at an outer edge of a second porous body adjacent to the first porous body, respectively, so as to extend to be superimposed over the frame body. The extended portions of the first and second porous bodies intervene between the frame body and the separator.

A solid oxide fuel cell array has pairs of a first connection member and a second connection member. Each pair electrically connects two adjacent first and second fuel cells to electrically connect the plurality of fuel cells in series. The second fuel cell has the first connection member connected to the outer side electrode layer of the second fuel cell at a distance D1 measured from the upper terminal end of the outer side electrode layer of the second fuel cell and has the second connection member connected to the outside side electrode layer of the second fuel cell at a distance D2 measured from the lower terminal end of the outer side electrode of the second fuel cell. The distance D2 is longer than the distance D1.

The present invention comprises a plurality of fuel cells connected to each other in series, and a reformer configured to reform raw fuel, wherein reformed fuel by the reformer is supplied to a first stage of the plurality of fuel cells, and the fuel cell on the first stage is provided with a methane reaction suppressing function which suppresses reaction of methane included in the reformed fuel to a larger extent than at least one fuel cell on a second and later stages. Suppressing temperature drop due to endothermic reaction in the fuel cell on the first stage can improve the efficiency of electric power generation of the fuel cell system having the plurality of fuel cells arranged in series.