Solid oxide fuel cell and manufacturing method thereof

Abstract

An electric power generation cell 1 is constituted by arranging a fuel electrode layer 4 on one side of a solid electrolyte layer 3 and an air electrode layer 2 on the other side of the solid electrolyte layer 3 . The solid electrolyte layer 3 is constituted of an oxide ion conductor mainly composed of a lanthanum gallate based oxide. The fuel electrode layer 4 is constituted of a porous sintered compact having a highly dispersed network structure in which a skeletal structure formed of a consecutive array of metal grains is surrounded by mixed conductive oxide grains. For the air electrode layer 2 , a porous sintered compact mainly composed of cobaltite is used. This configuration reduces the overpotentials of the respective electrodes and the IR loss of the solid electrolyte layer 3 , and accordingly can actualize a solid oxide type fuel cell excellent in electric power generation efficiency.

1 . A solid oxide fuel cell comprising an electric power generation cell ( 1 ) constituted by arranging a fuel electrode layer ( 4 ) on one side of a solid electrolyte layer ( 3 ) and an air electrode layer ( 2 ) on the other side of the solid electrolyte layer ( 3 ), wherein: 
 said solid electrolyte layer ( 3 ) is an oxide ion conductor mainly composed of a lanthanum gallate based oxide;    said fuel electrode layer ( 4 ) is a porous sintered compact having a highly dispersed network structure in which a skeletal structure formed of a consecutive array of metal grains is surrounded by mixed conductive oxide grains; and    said air electrode layer ( 2 ) is a porous sintered compact mainly composed of cobaltite.    
     
     
         2 . The solid oxide fuel cell according to  claim 1 , wherein: 
 said solid electrolyte layer ( 3 ) is a lanthanum gallate based oxide having a perovskite structure represented by La x Sr 1-x Ga y Mg 1-Y-Z MzO 3-δ  where 0.5<X<1, 0.7<Y<1 and 0<Z<0.1 (here, M denotes one or more types of metallic elements selected from the group consisting of Co, Fe, and Ni, and 3-δ denotes the number of oxygen atoms);    said fuel electrode layer ( 4 ) comprises a skeletal structure formed of a consecutive array of metal grains, of 0.9 μm or less in average primary grain size, of at least one type selected from the group consisting of Ni, Pt and Ru; and    said mixed conductive grains are made of an oxide containing cerium represented by CeO 2  or (CeO 2 ) 1-a (LO n ) a  where 0<a<0.4 (here, L denotes at least one type of cation selected from the group consisting of a monovalent alkali metal cation, a divalent alkaline earth metal cation and a trivalent rare earth element cation, and n denotes the number of oxygen atoms).    
     
     
         3 . The solid oxide type fuel cell according to  claim 1 , wherein: 
 said air electrode layer ( 2 ) is made of an oxide mainly composed of samarium strontium cobaltite having a perovskite structure represented by Sm c Sr 1-c CoO 3-γ where 0.1<c<0.9 (here, 3-γ denotes the number of oxygen atoms).    
     
     
         4 . A manufacturing method of a solid oxide fuel cell comprising an electric power generation cell ( 1 ) constituted by arranging a fuel electrode layer ( 4 ) on one side of a solid electrolyte layer ( 3 ) and an air electrode layer ( 2 ) on the other side of the solid electrolyte layer ( 3 ), in which: 
 said solid electrolyte layer ( 3 ) is an oxide ion conductor mainly composed of a lanthanum gallate based oxide;    said fuel electrode layer ( 4 ) is a porous sintered compact having a highly dispersed network structure in which a skeletal structure formed of a consecutive array of metal grains is surrounded by mixed conductive oxide grains; and    said air electrode layer ( 2 ) is a porous sintered compact mainly composed of cobaltite, wherein:    said fuel electrode layer ( 4 ) is manufactured by sintering, in an oxidative atmosphere at a temperature of 900° C. to 1,500° C., a powder having a highly dispersed network structure in which mixed conductive oxide grains produced by the spray thermal decomposition method surround the skeletal structure formed of a consecutive array of metal grains.    
     
     
         5 . The solid oxide type fuel cell according to  claim 2 , wherein: 
 said air electrode layer ( 2 ) is made of an oxide mainly composed of samarium strontium cobaltite having a perovskite structure represented by Sm c Sr 1-c CoO 3-γ  where 0.1<c<0.9 (here, 3-γ denotes the number of oxygen atoms).