Ceramic Fuel Cells Limited

Donald Jaffrey

Karl Foger

A fuel cell gas separator member () comprises a layer () of copper or copper-based alloy having a layer () of oxidation-resistant material such as AlOon the cathode side (). A protective layer () may also be provided on the anode-side () of the copper or copper-based alloy layer. The copper-based alloy may be aluminium bronze in which case the oxidation-resistant layer may form automatically. Alternatively, the copper or copper-based alloy layer () may be wrapped in a foil () of heat resistant steel. Other possibilities are disclosed.

Fuel cell gas separator

A metal oxide ceramic material such as alumina or chromia which has been rendered electrically conductive through its thickness by the incorporation of silver into the material. The metal oxide ceramic material may be in the form of a layer on a substrate such as a bipolar plate or other component for a fuel cell assembly. The electrical conductivity may be achieved by heating the ceramic material and a silver-containing material in contact with each other to at least 750&deg; C. such that silver migrates from the silver-containing material the metal oxide ceramic material and creates electrically conductive pathways through the ceramic material. In a particular embodiment, the substrate is a steel which forms an alumina, chromia or alumina-rich or chromia-rich surface layer in oxidizing atmosphere and the silver-containing material is heated in an oxidizing atmosphere in contact with the steel to cause the surface layer to form on the steel and to cause silver from the silver-containing material to occur in and create the electrically conductive pathways through the layer. The silver-containing material may be commercially pure silver or other forms of silver.

Electrically conductive ceramics

A solid oxide fuel cell assembly has a gas separator plate and a silver electrically conducting layer between the gas separator plate and the cathode layer of the adjacent fuel cell. The conductive layer may be in the form of a mesh or other sheet which permits oxygen-containing gas in gas channels to pass through the conductive layer and access to the cathode layer. The silver may be pure, alloyed, present as an intermetallic compound, or present as a composite with a non-metal.

Electrical conductivity in a fuel cell assembly

A steel composition particularly useful for components of solid oxide fuel cells, for example a connector plate for collecting electrical current from a solid oxide fuel cell, consisting of, in weight percent, 18-28.5 Cr, 0.001-0.20 C, <0.1 Si, 0.005-0.10 Mn, <1.0 Ni, <0.25 N, <0.05 S, <0.08 P, <0.06 Al, <0.25 Additional Defined Metals, and 0.005-0.50 REM, wit the residue iron, excluding incidental impurities, where Additional Defined Metals is the sum of titanium, niobium, vanadium, molybdenum and copper, and REM is one or more of the rare earth metal elements in the group of the lanthanide elements 57 to 71, scandium and yttrium.

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Mount Dandenong, Australia

Donald Jaffrey