Solid oxide fuel cell

Abstract

A solid oxide fuel cell provided with a power cell ( 1 ) in which a fuel electrode layer ( 4 ) is arranged on one surface of a solid electrolyte layer ( 3 ) and an air electrode layer ( 2 ) is arranged on the other surface thereof, wherein the solid electrolyte layer ( 3 ) has a two layer structure including a first electrolyte layer ( 3 a ) made of a ceria based oxide material and a second electrolyte layer ( 3 b ) made of a lanthanum gallate based oxide material, and the second electrolyte layer is formed on the side of the air electrode layer. It is preferable that the first electrolyte layer is formed thinner than the second electrolyte layer. According to such a configuration, there can be provided a solid oxide fuel cell comprising an inexpensive solid electrolyte layer which reduces the contact resistances in the interfaces between the solid electrolyte layer and the respective electrode layers, and thereby improves the generation efficiency. Additionally, by adopting a configuration in which the composition ratio of component materials in the fuel electrode layer ( 4 ) is graded along the thickness thereof, there can be provided a solid oxide fuel cell in which the generation characteristics of the power cell are improved and the durability of the solid oxide fuel cell is improved. Preferably, the material composition for the fuel electrode layer ( 4 ) is a mixture of Ni and CeSmO 2 , wherein the composition ratio of component materials is graded along the thickness thereof in such a way that the quantity of Ni is made less than the quantity of CeSmO 2 near the boundary interface with said solid electrolyte layer, and the mixing ratio of Ni is gradually increased with an increasing distance away from the interface.

1 . A solid oxide fuel cell provided with a power cell ( 1 ) formed by arranging a fuel electrode layer ( 4 ) on one surface of a solid electrolyte layer ( 3 ) and an air electrode layer ( 2 ) on the other surface thereof, wherein: 
 said solid electrolyte layer consists of a two layer structure comprising a first electrolyte layer ( 3   a ) made of a ceria based oxide material and a second electrolyte layer ( 3   b ) made of a lanthanum gallate based oxide material; and    said second electrolyte layer is formed on the side of said air electrode layer.    
   
   
       2 . The solid oxide fuel cell according to  claim 1 , wherein said first electrolyte layer ( 3   a ) is formed thinner than said second electrolyte layer ( 3   b ).  
   
   
       3 . A solid oxide fuel cell provided with a power cell ( 1 ) formed by arranging a fuel electrode layer ( 4 ) on one surface of a solid electrolyte layer ( 3 ) and an air electrode layer ( 2 ) on the other surface thereof, wherein: 
 the composition ratio of component materials in said fuel electrode layer is graded along the thickness thereof.    
   
   
       4 . The solid oxide fuel cell according to  claim 3 , wherein said fuel electrode layer ( 4 ) has a layered structure comprising two or more layers, and the composition ratio of component materials in said fuel electrode layer is graded along the layering direction thereof by varying the composition ratio of component materials in the respective layers.  
   
   
       5 . The solid oxide fuel cell according to  claim 3 , wherein the material composition for said fuel electrode layer ( 4 ) is a mixture of Ni and CeSmO 2 , wherein the composition ratio of component materials is graded along the thickness thereof in such a way that the quantity of Ni is less than the quantity of CeSmO 2  near the interface with said solid electrolyte layer ( 3 ), and the mixing ratio of Ni is gradually increased with an increasing distance away from the interface.  
   
   
       6 . The solid oxide fuel cell according to  claim 4 , wherein the material composition for said fuel electrode layer ( 4 ) is a mixture of Ni and CeSmO 2 , wherein the composition ratio of component materials is graded along the thickness thereof in such a way that the quantity of Ni is less than the quantity of CeSmO 2  near the interface with said solid electrolyte layer ( 3 ), and the mixing ratio of Ni is gradually increased with an increasing distance away from the interface.