The performance of a solid polymer membrane electrolyte fuel cell under various operating conditions can be improved via use of electrodes comprising multiple layers of supported catalyst in which the layers comprise different catalyst loadings on their respective supports. Such an electrode comprises a first component catalyst layer adjacent the membrane electrolyte and a second component catalyst layer adjacent the first component layer. The loading of the catalyst in the first component layer is greater than that in the second component layer.

The fuel cell has an anode, a cathode, and a solid electrolyte layer. The cathode contains a main component configured by a perovskite oxide which is expressed by the general formula ABO.sub.3 and includes at least Sr at the A site. The solid electrolyte layer is disposed between the anode and the cathode. The cathode has a surface region and an inner region. The surface region is within 5 m from a surface opposite the solid electrolyte layer. The inner region is formed on a solid electrolyte layer side of the surface region. The surface region and the inner region respectively include a main phase configured by the perovskite oxide and a secondary phase configured by strontium sulfate. An occupied surface area ratio of the secondary phase in a cross section of the surface region is greater than an occupied surface area ratio of the secondary phase in a cross section of the inner region.

Electrochemical cells, such as those present within flow batteries, can include at least one electrode with one face being more hydrophilic than is the other. Such electrodes can lessen the incidence of parasitic reactions by directing convective electrolyte circulation toward a separator in the electrochemical cell. Flow batteries containing the electrochemical cells can include: a first half-cell containing a first electrode with a first face and a second face that are directionally opposite one another, a second half-cell containing a second electrode with a first face and a second face that are directionally opposite one another, and a separator disposed between the first half-cell and the second half-cell. The first face of both the first and second electrodes is disposed adjacent to the separator. The first face of at least one of the first electrode and the second electrode is more hydrophilic than is the second face.

A membrane electrode assembly and fuel cell having such assembly. The membrane electrode assembly has a polymer electrolyte membrane, two catalytic electrodes in contact with the polymer electrolyte membrane on both sides, namely an anode and a cathode, and two gas diffusion layers directly or indirectly adjoining the electrodes, namely an anode-side gas diffusion layer and a cathode-side gas diffusion layer. At least one of the gas diffusion layers may optionally feature a microporous layer facing the polymer electrolyte membrane. The sequence of layers is anode-side gas diffusion layer, anode-side microporous layer, anode, polymer electrolyte membrane, cathode, cathode-side microporous layer, cathode-side gas diffusion layer. A relative hydrophobicity of at least two of these components and/or a hydrophobicity gradient within at least one of these components, and a relative pore structure having pore size and/or porosity of at least two of these components and/or a gradient within the pore structure of at least one of these components, is designed in such a way that it promotes the transport of water via the polymer electrolyte membrane, preferably from the cathode side to the anode side.

Methods for optimizing, designing, making, and assembling various component parts and layers to produce optimized MEAs. Optimization is generally achieved by producing multi-layered MEAs wherein characteristics such as catalyst composition and morphology, ionomer concentration, and hydrophobicity/hydophilicity are specifically tuned in each layer. The MEAs are optimized for use with a variety of catalysts including catalysts with specifically designed and controlled morphology, chemical speciation on the bulk, chemical speciation on the surface, and/or specific hydrophobic or hydrophilic or other characteristics. The catalyst can incorporate non-platinum group metal (non-PGM) and/or platinum group metal (PGM) materials.

A system for manufacturing a shape-changed membrane-electrode assembly includes a first transportation unit configured to transport a first electrode film, a second transportation unit configured to transport a second electrode film, and a third transportation unit configured to transport an electrolyte membrane. Through a roll press, which includes a primary-reaction-section pattern and an auxiliary-reaction-section pattern, transfer pressure, the shape-changed membrane-electrode assembly can be kept uniform during a transfer pressure process, one of processes of manufacturing the membrane-electrode assembly.

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.

An object is to prevent an increase in overall thickness of a membrane electrode assembly. There is provided a membrane electrode assembly. The membrane electrode assembly comprises an electrolyte membrane; a catalyst layer that is formed on a surface of the electrolyte membrane and includes a catalyst and an ionomer; and a gas diffusion layer that is formed on a surface of the catalyst layer on an opposite side to the electrolyte membrane. The catalyst layer includes a first layer that is in contact with the electrolyte membrane and a second layer that is in contact with the gas diffusion layer. An amount of the ionomer in a first portion of the first layer that is in contact with the electrolyte membrane is larger than an amount of the ionomer in a second portion of the first layer that is in contact with the second layer. An amount of the ionomer in a third portion of the second layer that is in contact with the gas diffusion layer is larger than the amount of the ionomer in the first portion.

The invention relates to a method for determining a spatial distribution (Wc.sub.x,y.sup.i) of a parameter of interest (Wc) representative of a catalytic activity of an active layer of at least one electrode of an electrochemical cell, comprising steps in which a spatial distribution (Wc.sub.x,y.sup.i) of the parameter of interest (Wc) is determined depending on the spatial distribution (Q.sub.x,y.sup.e) of a second thermal quantity (Q.sup.e) estimated beforehand from the spatial distribution (T.sub.x,y.sup.c) of a set-point temperature (T.sup.c) and from the spatial distribution (D.sub.x,y.sup.r) of a first thermal quantity (D.sup.r).

A composite cathode includes: a layer including porous particles; and a first electrolyte disposed between porous particles of the layer including porous particles, wherein the first electrolyte is disposed on at least a portion of a surface of the layer including porous particles, and wherein a weight ratio of the porous particles to the first electrolyte is less than about 1:3.7.