Patent ID: 7691524

Claim:
An anode material for a fuel cell which is to be operated at a high temperature above 700° C., said anode material being a porous composite material with a heterogeneous phase of solid materials which is formed by two reticular systems which penetrate each other in interlaced manner of particles connected by sintering, namely a first reticular system of ceramic material, and a second reticular system of metallic material for the purpose of bringing about redox processes and an electrical conductivity, wherein the first reticular system is composed of large and small ceramic particles with average diameters d 50 greater than 5 μm or smaller than 1 μm respectively, wherein 50 to 80% of the first reticular system is formed from the large ceramic particles, and wherein the anode material formed by the first and second reticular systems has an irreversible change in length smaller than 0.002, determined by means of a test method in which the following measurements and evaluations are carried out at a temperature which is at least the same as the operating temperature of the fuel cell: a linear elongation of a sample of the anode material is measured in the oxidized state of the second reticular system and a value L 1 is determined; the second reticular system is reduced, is oxidized again after at least one hour, and a value L 2 of the linear elongation is determined for the newly oxidized state, and the irreversible change in length is obtained as the ratio (L 1 −L 2 ):L 1 , wherein anode material standing in connection with an electrolyte layer forms a heterogeneous phase composed of the two reticular systems; wherein the large and small ceramic particles form “burr corpuscles” of stable shape, which are dispersed in insular manner in the heterogeneous phase; and wherein the “burr corpuscles” are associated into a “adherent burr composite” through which the heterogeneous phase is stabilized against changes of shape, with dimensional characteristics of the heterogeneous phase remaining largely intact at a boundary surface to the electrolyte layer through this stabilization.