Low Temperature Electrolytes for Solid Oxide Cells Having High Ionic Conductivity

Abstract

Methods for forming a metal oxide electrolyte improve ionic conductivity. Some of those methods involve applying a first metal compound to a substrate, converting that metal compound to a metal oxide, applying a different metal compound to the metal oxide, and converting the different metal compound to form a second metal oxide. Electrolytes so formed can be used in solid oxide fuel cells, electrolyzers, and sensors, among other applications.

We claim: 
     
         1 . A method of enhancing ionic conductivity in a metal oxide electrolyte comprising a first material and a first metal oxide comprising:
 applying a first metal compound to the first material; and   converting at least some of the first metal compound to form the first metal oxide thereby forming the metal oxide electrolyte;   wherein the metal oxide electrolyte has an ionic conductivity greater than the bulk ionic conductivity of the first material and of the first metal oxide,   wherein the first material comprises mica.   
     
     
         2 . The method of  claim 1 , wherein the first material comprises crystalline material. 
     
     
         3 . The method of  claim 1 , wherein the first material comprises a metal oxide. 
     
     
         4 . The method of  claim 1 , wherein the first metal oxide is chosen from strontium titanate, titania, alumina, zirconia, yttria-stabilized zirconia, alumina-doped yttria-stabilized zirconia, iron-doped zirconia, magnesia, ceria, samarium-doped ceria, gadolinium-doped ceria, and combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the first metal oxide is chosen from alumina, titania, zirconia, yttria-stabilized zirconia, alumina-doped yttria-stabilized zirconia, iron-doped zirconia, magnesia, ceria, samarium-doped ceria, gadolinium-doped ceria, and combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the first metal oxide comprises yttria-stabilized zirconia. 
     
     
         7 . The method of  claim 6 , wherein the yttria-stabilized zirconia comprises from about 10 mol % to about 20 mol % yttria. 
     
     
         8 . The method of  claim 6 , wherein the yttria-stabilized zirconia comprises from about 12 mol % to about 18 mol % yttria. 
     
     
         9 . The method of  claim 6 , wherein the yttria-stabilized zirconia comprises from about 14 mol % to about 16 mol % yttria. 
     
     
         10 . The method of  claim 1 , further comprising:
 applying an epoxy to the metal oxide.   
     
     
         11 . The method of  claim 1 , comprising:
 applying a second metal compound to the metal oxide electrolyte; and   converting at least some of the second metal compound to form a second metal oxide on the first metal oxide, thereby forming the metal oxide electrolyte.   
     
     
         12 . The method of  claim 11 , wherein the second metal oxide is chosen from strontium titanate, titania, alumina, zirconia, yttria-stabilized zirconia, alumina-doped yttria-stabilized zirconia, iron-doped zirconia, magnesia, ceria, samarium-doped ceria, gadolinium-doped ceria, and combinations thereof. 
     
     
         13 . The method of  claim 1 , wherein the metal oxide electrolyte comprises at least one catalytic material chosen from platinum, palladium, rhodium, nickel, cerium, gold, silver, zinc, lead, ruthenium, rhenium, or a mixture thereof. 
     
     
         14 . The method of  claim 11 , wherein the metal oxide electrolyte comprises at least one catalytic material chosen from platinum, palladium, rhodium, nickel, cerium, gold, silver, zinc, lead, ruthenium, rhenium, or a mixture thereof. 
     
     
         15 . A metal oxide electrolyte comprising:
 a first material and a metal oxide, wherein the metal oxide is formed by applying a metal compound to the first material; and   converting at least some of the metal compound to form the metal oxide,   wherein the first material and the metal oxide have an ionic conductivity greater than the bulk ionic conductivity of the first material and of the metal oxide; wherein the first material comprises mica.   
     
     
         16 . A solid oxide cell, comprising:
 an inner tubular electrode having an outer surface;   an outer electrode; and   a metal oxide electrolyte adapted to provide ionic conductivity between the inner tubular electrode and the outer electrode;   wherein the metal oxide electrolyte comprises a plurality of thin sheets oriented substantially perpendicular to the outer surface of the inner tubular electrode, and a metal oxide contacting the thin sheets;   wherein the thin sheets are mica.