Disclosed is an electrolyte membrane including an antioxidant containing elemental sulfur or a sulfur compound to improve antioxidant activity and resistance to acids. In addition, a membrane-electrode assembly including the electrolyte membrane is disclosed.

Disclosed is an electrolyte membrane including an antioxidant containing elemental sulfur or a sulfur compound to improve antioxidant activity and resistance to acids. In addition, a membrane-electrode assembly including the electrolyte membrane is disclosed.

Membrane assemblies and separation layer(s) for electrochemical devices such as fuel cells and/or electrolyzers are provided, as well as their production methods. The separation layer(s) include surface-charged particles such as LDH particles to strengthen the membranes, enhance their ionic conductivity and prevent or reduce membrane dehydration and/or chemical degradation. In various configurations a single or few, relatively thick separation layer(s) with surface-charged particles may be used, while in other configurations alternating layers of ionomeric material and layers with surface-charged particles may be used, optimizing ionic conductivity with mechanical strength. Thin protective layers with solids content up to 100% may be set adjacent to the electrodes, and the orientation of the surface-charged particles may be set to enhance the ion conductivity of the respective layer.

Disclosed are: a polymer electrolyte membrane which can prevent ionic conductor loss even upon the occurrence of chemical degradation in the ionic conductor according to long term use and thus can be significantly improved in chemical durability; a manufacturing method therefor; and an electrochemical device comprising same. The polymer electrolyte membrane of the present disclosure comprises a polymer electrolyte material. The polymer electrolyte material comprises an ionic conductor and a crosslinker unbound to the ionic conductor. The crosslinker has at least one cross-linkable functional group which can couple with the ionic conductor that has been degraded, thereby causing crosslinking with the ionic conductor.

Disclosed are: a polymer electrolyte membrane which can prevent ionic conductor loss even upon the occurrence of chemical degradation in the ionic conductor according to long term use and thus can be significantly improved in chemical durability; a manufacturing method therefor; and an electrochemical device comprising same. The polymer electrolyte membrane of the present disclosure comprises a polymer electrolyte material. The polymer electrolyte material comprises an ionic conductor and a crosslinker unbound to the ionic conductor. The crosslinker has at least one cross-linkable functional group which can couple with the ionic conductor that has been degraded, thereby causing crosslinking with the ionic conductor.

Disclosed are an additive for a polymer electrolyte membrane fuel cell and a polymer electrolyte membrane fuel cell including the additive. The additive may include a carbon material having a predetermined shape and a perovskite compound having the formula Ce(Zr.sub.xTi.sub.1-x)O.sub.3, wherein x satisfies 0<x<1, and wherein the perovskite compound is deposited on the carbon material.

Disclosed are an additive for a polymer electrolyte membrane fuel cell and a polymer electrolyte membrane fuel cell including the additive. The additive may include a carbon material having a predetermined shape and a perovskite compound having the formula Ce(Zr.sub.xTi.sub.1-x)O.sub.3, wherein x satisfies 0<x<1, and wherein the perovskite compound is deposited on the carbon material.

Disclosed is an electrolyte membrane for fuel cells including a catalytic composite including a catalytic particle coated with an oxygen-permeable material and a method of producing the same. The electrolyte membrane for fuel cells includes an ion transport layer including an ionomer having proton conductivity and a catalytic composite dispersed in the ion transport layer, and the catalytic composite includes a catalytic particle including a catalytic metal component having activity of decomposing hydrogen peroxide and a coating layer formed on at least a part of a surface of the catalytic particle and including an oxygen-permeable material.

Disclosed is an electrolyte membrane for fuel cells including a catalytic composite including a catalytic particle coated with an oxygen-permeable material and a method of producing the same. The electrolyte membrane for fuel cells includes an ion transport layer including an ionomer having proton conductivity and a catalytic composite dispersed in the ion transport layer, and the catalytic composite includes a catalytic particle including a catalytic metal component having activity of decomposing hydrogen peroxide and a coating layer formed on at least a part of a surface of the catalytic particle and including an oxygen-permeable material.

Disclosed are an antioxidant for fuel cells, a membrane electrode assembly including the same and a method for preparing the antioxidant. The antioxidant for fuel cells includes a core including at least one selected from the group consisting of a metal oxide (M.sub.xO.sub.k) and a complex metal oxide (M.sub.xN.sub.yO.sub.j, N and M being different metals), and an outer portion (e.g., a shell) located on or over a surface of the core and formed by performing reduction treatment of the surface of the core using a thiourea-based compound. The outer portion includes metal cations (M.sup.(x-n)+, n being a natural number of 1 or more) having a smaller oxidation number than a valency of the metal (M) of the core.