Fuel cell and electrolyzer hotbox module using conductive zirconia stacks

Abstract

Modular pressurized hotbox for use and substitution in a variety of pressurized electrochemical applications to include reversible solid oxide electrolyzer and fuel cells, energy storage systems, renewable fuel production, solid-state hydrogen pumping and liquefaction, and oxygen transport membranes. This is enabled by mixed electronic and ionic conducting compositions of vanadia-yttria and vanadia-calcia stabilized zirconia and a dry powder method of manufacture for ceramic core stacks.

What is claimed is: 
     
         1 . A method for fabricating a fuel cell stack, comprising:
 (a) first pressing ceramic powder in a plurality of successive layers of interconnects, anodes, electrolytes, and cathodes, wherein at least the anodes and the cathodes comprise a mixed electronic and ionic conductor and the interconnects include an embedded burnout material resulting in a stack;   (b) second pressing the stack; and   (c) sintering the stack.   
     
     
         2 . The method of  claim 1  wherein the mixed electronic and ionic conductor for the anodes and/or the cathodes is vanadia-yttria stabilized zirconia. 
     
     
         3 . The method of  claim 1 , wherein the interconnects comprise vanadia-calcia stabilized zirconia. 
     
     
         4 . The method of  claim 1 , wherein the mixed electronic and ionic conductor for the anodes and/or the cathodes is vanadia-yttria stabilized zirconia, the interconnects comprise vanadia-calcia stabilized zirconia, the electrolyte comprises yttria-stabilized zirconia, and the burnout material comprises a carbon-based polymer, graphite flake, low temperature melting metal, or any type of paper. 
     
     
         5 . A method for fabricating a fuel cell stack, comprising:
 (a) pressing ceramic powder resulting in at least one layer selected from an interconnect, an anode comprised of a mixed electronic and ionic conductor, an electrolyte, or a cathode comprised of a mixed electronic and ionic conductor, wherein a burnout material is embedded in the interconnect;   (b) repeating step (a) a plurality of times resulting in a stack of a plurality of successive layers;   (c) pressing the resulting stack; and   (d) sintering the resulting pressed stack thereby burning away the burnout material and resulting in a fuel cell stack.   
     
     
         6 . The method of  claim 5 , wherein (a) and (b) together comprise:
 pressing a vanadia-calcia stabilized zirconia nanopowder to form a first interconnect layer;   embedding the burnout material in the interconnect layer;   depositing a vanadia-yttria stabilized zirconia nanopowder onto the interconnect layer;   pressing the deposited vanadia-yttria stabilized zirconia nanopowder to form a first electrode layer;   depositing a yttria-stabilized zirconia nanopowder onto the first electrode layer;   pressing the deposited yttria-stabilized zirconia nanopowder to form an electrolyte layer;   depositing a vanadia-yttria stabilized zirconia nanopowder onto the electrolyte layer; and   pressing the deposited vanadia-yttria stabilized zirconia nanopowder to form a second electrode layer;   depositing a vanadia-calcia stabilized zirconia nanopowder onto the second electrode layer; and   pressing the deposited vanadia-calcia stabilized zirconia nanopowder to form a second interconnect layer.   
     
     
         7 . The method of  claim 5 , wherein the mixed electronic and ionic conductor for the anode and/or the cathode is vanadia-yttria stabilized zirconia. 
     
     
         8 . The method of  claim 7 , wherein the vanadia is present in an amount of 5-20 mol %. 
     
     
         9 . The method of  claim 7 , wherein the zirconia is doped only with vanadia and yttria. 
     
     
         10 . The method of  claim 7 , wherein the vanadia-yttria stabilized zirconia has a cubic fluorite structure with 4 molecules per unit cell and having metal cations randomly distributed on a metal ion sublattice and oxygen ions and oxygen vacancies randomly distributed on an oxygen ion sublattice. 
     
     
         11 . The method of  claim 10 , wherein the metal cations are Zr +4 , Y +3 , and V +3 . 
     
     
         12 . A method for fabricating a heat exchanger stack, comprising:
 (a) first pressing ceramic powder in a plurality of layers interleaved with a plurality of layers of burnout material;   (b) second pressing the stack; and   (c) sintering the stack.   
     
     
         13 . A method for fabricating a partial-pressure oxygen separator stack, comprising:
 (a) first pressing a mixed electronic and ionic conductor ceramic powder in a plurality of layers interleaved with a plurality of layers of burnout material;   (b) second pressing the stack; and   (c) sintering the stack.