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Method of making an electrochemical device for the recovery of oxygen from an oxygen-containing feed gas comprising (a) preparing a green electrochemical device by assembling a green electrolyte layer, a green anode layer in contact with the green electrolyte layer, a green cathode layer in contact

Method of making an electrochemical device for the recovery of oxygen from an oxygen-containing feed gas comprising (a) preparing a green electrochemical device by assembling a green electrolyte layer, a green anode layer in contact with the green electrolyte layer, a green cathode layer in contact with the green electrolyte layer, a green anode-side gas collection interconnect layer in contact with the green anode layer, and a green cathode-side feed gas distribution interconnect layer in contact with the green cathode layer; and (b) sintering-the green electrochemical device by heating to yield a sintered electrochemical device comprising a plurality of sintered layers including a sintered anode-side gas collection interconnect layer in contact with the anode layer and adapted to collect oxygen permeate gas, wherein each sintered layer is bonded to an adjacent sintered layer during sintering.

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The invention claimed is: 1. A method of making an electrochemical device for the recovery of oxygen from an oxygen-containing feed gas comprising (a) preparing a green electrochemical device by assembling a green electrolyte layer, a green anode layer in contact with the green electrolyte layer, a

The invention claimed is: 1. A method of making an electrochemical device for the recovery of oxygen from an oxygen-containing feed gas comprising (a) preparing a green electrochemical device by assembling a green electrolyte layer, a green anode layer in contact with the green electrolyte layer, a green cathode layer in contact with the green electrolyte layer, a green anode-side gas collection interconnect layer in contact with the green anode layer, and a green cathode-side gas distribution interconnect layer in contact with the green cathode layer, wherein either or both of the green anode layer and the green cathode layer comprises a layer of green electrode material in contact with a layer of green electrode support material; and (b) sintering the green electrochemical device by heating to yield a sintered electrochemical device comprising a plurality of sintered layers including a sintered anode-side gas collection interconnect layer in contact with the anode layer and adapted to collect oxygen permeate gas, wherein each sintered layer is bonded to an adjacent sintered layer during sintering. 2. The method of claim 1 wherein the sintered electrochemical device comprises a dense sintered electrolyte layer, a porous sintered cathode layer, and a porous sintered anode layer. 3. The method of claim 2 wherein the sintered anode-side gas collection interconnect layer comprises dense material and includes gas collection channels. 4. The method of claim 2 wherein at least a portion of the green electrolyte layer is prepared from an electrolyte precursor powder comprising an oxide of cerium and an oxide or oxides of one or more elements selected from the group consisting of cobalt, yttrium, gadolinium, and samarium. 5. The method of claim 4 wherein the surface area of the electrolyte precursor powder is between about 3 m2/g and about 20 m2/g. 6. The method of claim 4 wherein the green electrolyte layer comprises a peripheral region or rim prepared from an electrolyte precursor powder consisting essentially of oxides of cerium and cobalt and the dense sintered electrolyte layer comprises a dense peripheral region or rim consisting essentially of oxides of cerium and cobalt. 7. The method of claim 1 wherein the green electrode material is prepared from (1) a first electrode precursor powder comprising an oxide of cerium and an oxide or oxides of one or more elements selected from the group consisting of cobalt, yttrium, gadolinium, and samarium and (2) a second electrode precursor powder comprising oxides of lanthanum, strontium, cobalt, and iron. 8. The method of claim 7 wherein at least a portion of the layer of green electrode material is prepared from a slip comprising the first electrode precursor powder, the second electrode precursor powder, and a pore former. 9. The method of claim 1 wherein at least a portion of the layer of green electrode support material is prepared from an electrode support precursor powder comprising oxides of lanthanum, calcium, and manganese. 10. The method of claim 9 wherein at least a portion of the layer of green electrode support material is prepared from a slip comprising the electrode support precursor powder and a pore former. 11. The method of claim 1 wherein any of the layers are formed by tape casting. 12. The method of claim 1 wherein (1) the green electrolyte layer is in contact with the layer of green electrode material; (2) the green electrolyte layer is prepared from an electrolyte precursor powder comprising oxides of cerium and cobalt and an oxide or oxides of one or more elements selected from the group consisting of yttrium, gadolinium, and samarium; (3) the layer of green electrode material is prepared from an electrode precursor powder comprising an oxide of cerium and an oxide or oxides of one or more elements selected from the group consisting of cobalt, yttrium, gadolinium, and samarium; and (4) the surface area of the electrolyte precursor powder is greater than the surface area of the electrode precursor powder. 13. The method of claim 12 wherein the surface area of the electrolyte precursor powder is between about 3 m2/g and about 20 m2/g and the surface area of the electrode precursor powder is between about 0.25 m2/g and about 10 m2/g. 14. The method of claim 1 wherein either or both of the green anode-side gas collection interconnect layer and the green cathode-side gas distribution interconnect layer are prepared from material that (1) includes an interconnect precursor powder comprising calcium carbonate and oxides of lanthanum and manganese and (2) excludes pore formers. 15. The method of claim 14 which further comprises forming gas channels in the green anode-side gas collection interconnect layer and the green cathode-side gas distribution interconnect layer. 16. The method of claim 1 wherein the green electrochemical device is assembled by (1) forming a green electrode-electrolyte layer assembly by placing the green anode layer against one surface of the green electrolyte layer, placing the green cathode layer against the other surface of the green electrolyte layer, applying a pressure in the range of 5 to 100 MPa to the layer assembly in a direction normal to the layer assembly while maintaining the temperature of the layer assembly in the range of 50 to 100° C., thereby forming a laminated electrode-electrolyte assembly; and (2) forming a green electrolyte-electrode-interconnect assembly by coating the green anode-side gas collection interconnect layer and the green cathode-side gas distribution interconnect layer with a solvent, placing the green anode-side gas collection interconnect layer against one surface of the laminated electrode-electrolyte assembly, placing the green cathode side gas distribution interconnect layer against the other surface of the laminated electrode-electrolyte assembly, and applying a pressure in the range of 0.1 to 50 MPa to the green electrolyte-electrode-interconnect assembly in a direction normal to the assembly. 17. The method of claim 1 wherein the sintered electrochemical device includes a porous sintered anode layer and a porous sintered cathode layer and wherein the method further comprises the additional steps of forming a liquid precursor containing a powdered electrocatalyst, introducing the liquid precursor into the pores of the sintered anode and cathode layers, and heating the sintered electrochemical device to a temperature in the range of about 500° C. to about 900° C. 18. The method of claim 17 wherein the electrocatalyst is selected from the group consisting of a noble metal and one or more transition metal oxides. 19. The method of claim 18 wherein the electrocatalyst comprises a material having the composition (La1-ySry)A(Co1-zFez)B O3-δ, where the ratio A/B on a molar basis is between 0.95 and 1.05, 0.2<y<0.8, 0≦z≦1, and δ is dependent on the valence and amount of the cations in order to satisfy electroneutrality. 20. The method of claim 18 wherein the electrocatalyst comprises a material having the composition (La1-ySry)A(Co)BO3-δ, where the ratio A/B on a molar basis is between 1.00 and 1.02, 0.4≦y≦0.7, and δ is dependent on the valence and amount of the cations in order to satisfy electroneutrality. 21. A method of making an electrochemical device for the recovery of oxygen from an oxygen-containing feed gas comprising (a) preparing a green electrochemical device by assembling a green electrolyte layer, a green anode layer in contact with the green electrolyte layer, a green cathode layer in contact with the green electrolyte layer, a green anode-side gas collection interconnect layer in contact with the green anode layer, and a green cathode-side gas distribution interconnect layer in contact with the green cathode layer, wherein the green anode layer comprises (1) a central region prepared from one or more metal oxide precursor powders and a pore former and (2) a peripheral region prepared from material that includes a metal oxide precursor powder and excludes pore formers; and (b) sintering the green electrochemical device by heating to yield a sintered electrochemical device comprising a plurality of sintered layers including a sintered anode-side gas collection interconnect layer in contact with the anode layer and adapted to collect oxygen permeate gas, wherein each sintered layer is bonded to an adjacent sintered layer during sintering. 22. The method of claim 21 wherein the green cathode layer comprises (1) a central region prepared from one or more metal oxide precursor powders and a pore former and (2) a peripheral region prepared from material that includes a metal oxide precursor powder and excludes pore formers. 23. A method of making an electrochemical stack for the recovery of oxygen from an oxygen-containing feed gas comprising (a) preparing a plurality of green electrochemical cells, wherein each cell is made by assembling a green electrolyte layer, a green anode layer in contact with the green electrolyte layer, a green cathode layer in contact with the green electrolyte layer, a green anode-side gas collection interconnect layer in contact with the green anode layer, a green cathode-side gas distribution interconnect layer in contact with the green cathode layer, and a green end cap in contact with either the green anode-side gas collection interconnect layer or the green cathode-side gas distribution interconnect layer wherein either or both of the green anode layer and the green cathode layer comprises a layer of green electrode material in contact with a layer of green electrode support material; (b) assembling a stack of the green electrochemical cells to form a green stack having a top end and a bottom end, and adding a green terminal end cap at either the top end or the bottom end of the stack; and (c) co-sintering the stack by heating to yield the electrochemical stack comprising a plurality of sintered electrochemical cells, wherein each cell includes a sintered anode-side gas collection interconnect layer in contact with the anode layer and adapted to collect oxygen permeate gas, and wherein each sintered layer is bonded to an adjacent sintered layer during sintering. 24. The method of claim 23 wherein each sintered electrochemical cell comprises a plurality of sintered layers including a dense electrolyte layer, a porous anode layer bonded to one side of the dense electrolyte layer, a porous cathode layer bonded to the other side of the dense electrolyte layer, a dense anode-side interconnect layer in contact with the porous anode layer and having channels therein adapted for gas flow, and a dense cathode-side gas distribution interconnect layer in contact with the porous cathode layer and having channels therein adapted to distribute a feed gas to the cathode layer, wherein the coefficient of thermal expansion of the dense electrolyte layer is less than the coefficient of thermal expansion of the dense anode-side gas collection interconnect layer and the coefficient of thermal expansion of the dense cathode-side gas distribution interconnect layer. 25. The method of claim 24 wherein the dense electrolyte layer of any sintered electrochemical cell is in compression when the electrochemical stack is at temperatures in the range of about 500° C. to about 900° C.