Phase stable doped zirconia electrolyte compositions with low degradation

Patent metadata

Field	Value
Publication number	US-9413024-B2
Application number	US-201314055557-A
Country	US
Kind code	B2
Filing date	Oct 16, 2013
Priority date	Jan 26, 2010
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

A solid oxide fuel cell (SOFC) includes a cathode electrode, a solid oxide electrolyte, and an anode electrode. The electrolyte and/or electrode composition includes zirconia stabilized with (i) scandia, (ii) ceria, and (iii) at least one of yttria and ytterbia. The composition does not experience a degradation of ionic conductivity of greater than 15% after 4000 hrs at a temperature of 850° C.

First claim

The invention claimed is:

1. A scandia stabilized zirconia electrolyte composition for a solid oxide fuel cell, comprising;
a formula (ZrO 2 ) 1-w-x-b (Sc 2 O 3 ) w (CeO 2 ) x (Yb 2 O 3 ) b , where:
w=0.1; x=0.01 and b=0.01; or
w=0.1; x=0.01 and b=0.005; or
w=0.1; x=0.005 and b=0.005;
wherein:
the scandia stabilized zirconia electrolyte composition consists of a single layer located in direct contact with an anode on a first major surface of the single layer and in direct contact with a cathode on a second major surface of the single layer;
the composition does not experience a degradation of ionic conductivity of greater than 15% after 4000 hrs and at a temperature of 850° C.;
the composition comprises a cubic phase which substantially lacks tetragonal phase domains after operating in a solid oxide fuel cell at 850° C. for at least 4000 hours in at least one of air or hydrogen ambient; and
the composition does not experience a cubic to rhombohedral phase transition at a temperature of about 25 to 850° C.

2. The composition of claim 1 , wherein:
the composition is utilized as an electrolyte layer of a planar solid oxide fuel cell comprising the anode and the cathode;
the electrolyte layer supports the anode and cathode;
the solid oxide fuel cell is located in a solid oxide fuel cell stack adjacent to an interconnect comprising at least 94 wt % Cr, 4-6 wt % Fe and 0-1 wt % Y; and
a coefficient of thermal expansion of the electrolyte differs by 1% or less from a coefficient of thermal expansion of the interconnect.

3. The composition of claim 1 , wherein w=0.1; x=0.01 and b=0.01.

4. The composition of claim 1 , wherein w=0.1; x=0.01 and b=0.005.

5. The composition of claim 1 , wherein w=0.1; x=0.005 and b=0.005.

6. A scandia stabilized zirconia electrolyte composition for a solid oxide fuel cell, comprising a formula (ZrO 2 ) 1-w-x-b (Sc 2 O 3 ) w (CeO 2 ) x (Yb 2 O 3 ) b , where:
0.09≦w≦0.11; 0.005<x<0.015 and 0.0025<b≦0.015;
wherein:
the scandia stabilized zirconia electrolyte composition consists of a single layer located in direct contact with an anode on a first major surface of the single layer and in direct contact with a cathode on a second major surface of the single layer;
the composition does not experience a degradation of ionic conductivity of greater than 15% after 4000 hrs and at a temperature of 850° C.;
the composition comprises a cubic phase which substantially lacks tetragonal phase domains after operating in a solid oxide fuel cell at 850° C. for at least 4000 hours in at least one of air or hydrogen ambient; and
the composition does not experience a cubic to rhombohedral phase transition at a temperature of about 25 to 850° C.

7. The composition of claim 6 , wherein:
0.01≦x≦0.015 and 0.005≦b≦0.0125.

8. The composition of claim 7 , wherein:
0.005≦b≦0.01.

9. The composition of claim 8 , wherein:
w=0.1, b=0.01 and x=0.01.

10. The composition of claim 6 , wherein:
0.005≦x≦0.0125 and 0.0025≦b≦0.01.

11. The composition of claim 6 , wherein:
0.0025≦b≦0.0125.

12. The composition of claim 11 , wherein:
0.005≦x≦0.01 and 0.005≦b≦0.01.

13. The composition of claim 8 , wherein:
w=0.1 and x=0.01.

14. A planar fuel cell comprising the electrolyte of the composition of claim 6 .

15. A scandia stabilized zirconia electrolyte composition for a solid oxide fuel cell, comprising:
a formula (ZrO 2 ) 1-w-x-b (Sc 2 O 3 ) w (CeO 2 ) x (Yb 2 O 3 ) b , where w=0.1; x=0.01 and b=0.01;
wherein:
the scandia stabilized zirconia electrolyte composition consists of a single layer located in direct contact with an anode on a first major surface of the single layer and in direct contact with a cathode on a second major surface of the single layer;
the composition experiences a degradation of ionic conductivity of 1-5% after 4000 hrs and at a temperature of 850° C.;
the composition comprises a cubic phase which substantially lacks tetragonal phase domains after operating in a solid oxide fuel cell at 850° C. for at least 4000 hours in at least one of air or hydrogen ambient; and
the composition does not experience a cubic to rhombohedral phase transition at a temperature of about 25 to 850° C.

16. The composition of claim 15 , wherein the composition have a starting ionic conductivity of 0.14 S/cm or greater.

17. The composition of claim 16 , wherein the composition have a starting ionic conductivity of 0.16 to 0.17 S/cm.

Assignees

• Bloom Energy Corp

Inventors

• Armstrong Tad
• El Batawi Emad
• Janousek Martin
• Pillai Manoj

Classifications

• Y02E60/50

  Fuel cells · CPC title

• C04B2235/3225

  Yttrium oxide or oxide-forming salts thereof · CPC title

• C01P2002/52

  containing elements as dopants · CPC title

• C04B2235/3229

  Cerium oxides or oxide-forming salts thereof · CPC title

• Y02P70/56

  Cross-Sectional Technologies · mapped topic