A solid oxide fuel cell (SOFC) includes a ceramic electrolyte having a thickness of 100 microns or less, an anode laminated to a first side of the electrolyte, and a cathode located on a second side of the electrolyte opposite to the first side.

A method for production of a fuel cell includes:

a) Preparing a plurality of catalyst pastes which differ from each other at least in regard to one parameter influencing the catalytic activity,

b) Filling of at least two of the plurality of catalyst pastes into a first application means having a number of chambers corresponding to the number of catalyst pastes being filled, where only one of the catalyst pastes is filled into each of the chambers,

c) Filling of at least two of the plurality of catalyst pastes into a second application means having a number of chambers corresponding to the number of catalyst pastes being filled, where only one of the catalyst pastes is filled into each of the chambers,

d) Coating of a first side of a foil web of an electrolyte membrane which is moved past the first application means and the second application means by means of the first application means,

e) Coating of a second side of the foil web by means of the second application means,

f) Cutting of the resulting coated electrolyte membrane from the foil web and rotating of the electrolyte membrane by 90° with respect to a delivery direction of the foil web,

g) Placing of the electrolyte membrane between two flow field plates with a gradient in regard to the parameter which is oriented perpendicular to the flow field, and

h) Pressing together the flow field plates.

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.

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.

A cell stack includes a plurality of single cells, wherein each single cell includes a membrane electrode assembly having a cathode, an anode, an interposed membrane, and an anode gas diffusion layer wherein a) in a single cell, the anode gas diffusion layer and a cathode gas diffusion layer are arranged in relation to one another such that a first thickness gradient of the anode gas diffusion layer and a second thickness gradient of the cathode gas diffusion layer run opposite to one another or b) in two or more single cells, the anode gas diffusion layers are arranged in relation to one another such that an overall thickness gradient of the anode gas diffusion layers is minimized and/or wherein in two or more single cells, the cathode gas diffusion layers are arranged such that an overall thickness gradient of the cathode gas diffusion layers is minimized.

A hydrophilic porous carbon electrode which has excellent hydrophilicity, which has high reaction activity when used for a battery, and with which excellent battery characteristics is able to be obtained is provided. A hydrophilic porous carbon electrode is a sheet-form hydrophilic porous carbon electrode in which a carbon fiber is bonded using a resin carbide and has a contact angles θ.sub.A of water on both surfaces in a thickness direction being 0 to 15° and a contact angle θ.sub.B of water in a middle portion in the thickness direction being 0 to 15°. The hydrophilic porous carbon electrode is obtained by forming the carbon fiber and a binder fiber into a sheet, impregnating the sheet into a thermosetting resin, subjecting it to heat press processing, and then subjecting it to carbonization at 400 to 3000° C. in an inert atmosphere. The hydrophilic porous carbon electrode is transported and is subjected to a heat treatment while an oxidizing gas flows at 400 to 800° C. in a direction perpendicular to a direction in which the hydrophilic porous carbon electrode is transported to be subjected to hydrophilization.

A PEM fuel or electrolysis cell with an extended lifetime, improved performance and uniform and stable operation is disclosed wherein a membrane electrode assembly is provided with a gradient of one or more properties in combination with a modification of one or more control parameters of the cell during its operation.

Provided is a carbon substrate for a gas diffusion layer of a fuel cell. The carbon substrate has a structure, in which a plurality of unit carbon substrates are stacked. Each of the unit carbon substrates is a plate type substrate having a first surface and a second surface opposite to the first surface. Carbon fibers are randomly arranged on the first surface of the each unit carbon substrate. The number of the carbon fibers arranged in a machine direction of the unit carbon substrate is greater than the number of carbon fibers arranged in a transverse direction of the unit carbon substrate from the first surface to the second surface along a thickness direction of the unit carbon substrate; and, accordingly, an orientation gradient, in which the orientation in the machine direction increases from the first surface to the second surface, is shown.

A fuel cell includes a proton-exchange membrane, and a cathode and anode fixed on its opposite sides. The anode delimits a flow conduit between a molecular-oxygen inlet area and a water outlet area. The cathode includes a support for catalyst material. The support has first and second materials to which catalyst is fixed, the first material being a graphitized material. The second material has a resistance to corrosion by oxygen that is greater than that of the first material. A quantity of the second material at the inlet area is greater than a quantity of the second material at the water outlet. The cathode comprises a first layer including the first material and a second layer including the second material. A thickness of the second layer decreases between the molecular-oxygen inlet area and the water outlet area.

An example of a stable electrode structure is to use a gradient electrode that employs large platinum particle catalyst in the close proximity to the membrane supported on conventional carbon and small platinum particles in the section of the electrode closer to a GDL supported on a stabilized carbon. Some electrode parameters that contribute to electrode performance stability and reduced change in ECA are platinum-to-carbon ratio, size of platinum particles in various parts of the electrode, use of other stable catalysts instead of large particle size platinum (alloy, etc), depth of each gradient sublayer. Another example of a stable electrode structure is to use a mixture of platinum particle sizes on a carbon support, such as using platinum particles that may be 6 nanometers and 3 nanometers. A conductive support is typically one or more of the carbon blacks.