A membrane electrode assembly includes an electrolyte membrane, and a pair of electrodes sandwiching the electrolyte membrane. The pair of electrodes each include a catalyst layer, and a gas diffusion layer disposed on the catalyst layer on an opposite side to the electrolyte membrane. At least one of the catalyst layers contains first catalyst particles, and second catalyst particles. The first catalyst particles are either platinum particles or platinum alloy particles, or both. The second catalyst particles are core-shell particles having a core part and a shell part, the core part formed of at least one selected from transition metals other than platinum, the shell part covering the core part and formed of at least one of platinum and a platinum alloy. In the catalyst layer, the second catalyst particles are present in a smaller percentage in an electrolyte membrane side than they are in a gas diffusion layer side.

Disclosed are a manufacturing method of a membrane electrode assembly capable of increasing the interfacial adhesion between a polymer electrolyte membrane and a catalyst layer, improving substance delivery and performance, and enhancing hydrogen permeation resistance or oxygen permeability; a membrane electrode assembly manufactured thereby; and a fuel cell comprising the membrane electrode assembly. The manufacturing method of the present invention comprises the steps of: adding a catalyst and a first ionomer to a solvent and dispersing the same, thereby producing a dispersed mixture; adding a second ionomer to the dispersed mixture, thereby producing a coating composition; and applying the coating composition directly onto at least one side of the polymer electrolyte membrane.

A method for improving the performance and/or stability of non-precious metal catalysts in fuel cells and other electrochemical devices. Improved membrane electrode assemblies (MEAs) and fuel cells containing the same are provided. Such MEAs include a catalyst layer made up of at least two sub-layers containing ionomers of differing equivalent weights. The sub-layers may optionally contain mixtures of ionomers. Also provided are methods of making and using the described devices.

The electrochemical cell includes an anode, a cathode active layer, and a solid electrolyte layer disposed between the anode and the cathode active layer. The cathode active layer includes a first region which is disposed facing the solid electrolyte layer, and a second region which is disposed on the first region. An average particle diameter of first constituent particles which constitute the first region is smaller than an average particle diameter of second constituent particles which constitute the second region.

The present invention relates to a catalyst for a solid polymer fuel cell, including platinum, cobalt, and zirconium supported as a catalytic metal on a carbon powder carrier, in which the supporting ratio of platinum, cobalt, and zirconium on the carbon powder carrier is Pt:Co:Zr=3:0.5 to 1.5:0.1 to 3.0 by molar ratio. In the present invention, it is preferable that the peak position of Pt.sub.3Co seen in the X-ray diffraction pattern of catalyst particles is 2θ=41.10° or more and 42.00° or less, and moderate alloying has occurred in the catalytic metal.

A membrane electrode gas diffusion layer assembly for a fuel cell includes a membrane electrode assembly including an electrolyte membrane, an anode catalyst layer, and a cathode catalyst layer, an anode diffusion layer joined to the anode catalyst layer of the membrane electrode assembly, and a cathode diffusion layer joined to the cathode catalyst layer of the membrane electrode assembly, in which at least one of the anode diffusion layer and the cathode diffusion layer includes a microporous layer that makes contact with the membrane electrode assembly, the microporous layer contains a cerium compound, and at least one of the electrolyte membrane, the anode catalyst layer, and the cathode catalyst layer comprises cerium ions.

The present invention is a catalyst for a solid polymer fuel cell including: catalyst particles of platinum, cobalt and manganese; and a carbon powder carrier supporting the catalyst particles, wherein the component ratio (molar ratio) of the platinum, cobalt and manganese of the catalyst particles is of Pt:Co:Mn=1:0.06 to 0.39:0.04 to 0.33, and wherein in an X-ray diffraction analysis of the catalyst particles, the peak intensity ratio of a CoMn alloy appearing around 2=27 is 0.15 or less on the basis of a main peak appearing around 2=40. It is particularly preferred that the catalyst have a peak ratio of a peak of a CoPt.sub.3 alloy and an MnPt.sub.3 alloy appearing around 2=32 of 0.14 or more on the basis of a main peak.

An electrochemical cell includes a fuel electrode, an air electrode containing a perovskite type oxide as a main component, the perovskite type oxide being represented by a general formula ABO.sub.3 and containing La and Sr at the A site, and a solid electrolyte layer arranged between the fuel electrode and the air electrode. The air electrode includes a center portion and an outer peripheral portion, the center portion being located at a center of the air electrode in a plane direction perpendicular to a thickness direction of the air electrode, the outer peripheral portion surrounding the center portion in the plane direction. A first ratio of an La concentration to an Sr concentration detected at the outer peripheral portion through Auger electron spectroscopy is at least 1.1 times a second ratio of an La concentration to an Sr concentration detected at the center portion through Auger electron spectroscopy.

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.

Disclosed are a membrane-electrode assembly for fuel cells, a method of manufacturing the same and a fuel cell system containing the same. The membrane-electrode assembly for fuel cells includes an anode and a cathode facing each other, and a polymer electrolyte membrane interposed between the anode and the cathode, wherein at least one of the anode and the cathode further includes a porous support and a catalyst layer for fuel cells disposed on one surface of the porous support. The electrode of the membrane-electrode assembly is a free-standing electrode, and the electrode has excellent adhesivity to the polymer electrolyte membrane and thus can prevent performance deterioration resulting from detachment of the electrode from the polymer electrolyte membrane during operation of fuel cells, and in particular, can secure high durability since the electrode is not readily detached even under harsh operation environments.