Fuel electrodes for solid oxide electrochemical cell, processes for producing the same, and solid oxide electrochemical cells

Abstract

A fuel electrode for a solid oxide electrochemical cell includes: an electrode layer constituted of a mixed phase including an oxide having mixed conductivity and another oxide selected from the group including an aluminum-based oxide and a magnesium-based composite oxide, said another oxide having, supported on a surface part thereof, particles of at least one member selected from nickel, cobalt, and nickel-cobalt alloys; a meshy wiring formed on a surface layer part of the electrode layer and made of a material having higher electronic conductivity than the electrode layer; and a current collector which overlies the electrode layer and is in contact with at least the wiring.

What is claimed is: 
     
         1 . A process for producing a fuel electrode for a solid oxide electrochemical cell comprising the steps of:
 producing a mixture of oxide particles having mixed conductivity and nickel-aluminum composite oxide particles, cobalt-aluminum composite oxide particles, or composite oxide particles composed of a nickel-aluminum composite oxide and a cobalt-aluminum composite oxide;   superposing a layer of the mixture on a surface of a solid electrolyte and sintering the mixture layer; and   reducing the resultant sinter at a temperature of from 800° C. to 1,000° C.   
     
     
         2 . The process of  claim 1 , wherein the oxide particles having mixed conductivity are mixed with the nickel-aluminum composite oxide particles, cobalt-aluminum composite oxide particles, or composite oxide particles composed of a nickel-aluminum composite oxide and a cobalt-aluminum composite oxide, in a ratio of from 50:50 to 95:5 by weight. 
     
     
         3 . A process for producing a fuel electrode for a solid oxide electrochemical cell comprising the steps of:
 producing a mixture of oxide particles having mixed conductivity and nickel-magnesium composite oxide particles, cobalt-magnesium composite oxide particles, or composite oxide particles composed of a nickel-magnesium composite oxide and a cobalt-magnesium composite oxide;   superposing a layer of the mixture on a surface of a solid electrolyte and sintering the mixture layer; and   reducing the resultant sinter at a temperature of from 800° C. to 1,000° C.   
     
     
         4 . The process of  claim 3 , wherein the oxide particles having mixed conductivity are mixed with the nickel-magnesium composite oxide particles, cobalt-magnesium composite oxide particles, or composite oxide particles composed of a nickel-magnesium composite oxide and a cobalt-magnesium composite oxide, in a ratio of from 50:50 to 95:5 by weight. 
     
     
         5 . The process of  claim 3 , wherein the nickel-magnesium composite oxide particles and the cobalt-magnesium composite oxide particles contain at least one of Sc, Al, and Cr, the content of these elements being from 0.01% by mole to 1.0% by mole based on the magnesium-based composite oxides.