Sofc cathode compositions with improved resistance to sofc degradation

Patent metadata

Field	Value
Publication number	US-2016133947-A1
Application number	US-201514936250-A
Country	US
Kind code	A1
Filing date	Nov 9, 2015
Priority date	Nov 12, 2014
Publication date	May 12, 2016
Grant date	—

Abstract

A solid oxide fuel cell (SOFC) includes a solid oxide electrolyte with a zirconia-based ceramic, an anode electrode, and a cathode electrode that includes a ceria-based ceramic component and an electrically conductive component. Another SOFC includes a solid oxide electrolyte containing a zirconia-based ceramic, an anode electrode, and a cathode electrode that includes an electrically conductive component and an ionically conductive component, in which the ionically conductive component includes a zirconia-based ceramic containing scandia and at least one of ceria, ytterbia and yttria.

First claim

1 . A solid oxide fuel cell (SOFC), comprising:
a solid oxide electrolyte comprising a zirconia-based ceramic; an anode electrode; and a cathode electrode comprising a ceria-based ceramic component and an electrically conductive component.

2 . The SOFC of claim 1 , wherein the ceria-based ceramic component comprises at least one of samaria doped ceria (SDC), gadolinia doped ceria (GDC), and yttria doped ceria (YDC), and wherein the electrolyte is at least 80 wt % zirconia.

3 . The SOFC of claim 2 , wherein the ceria-based ceramic component comprises a formula Ce (1-x) A 2 O 2 , wherein A comprises at least one of samaria (Sm), gadolinium (Gd), and yttria (Y), wherein x is in a range of around 0.1 to 0.4, and wherein the solid oxide electrolyte comprises scandia stabilized zirconia.

4 . The SOFC of claim 1 , wherein the electrically conductive component comprises an electrically conductive ceramic selected from the group consisting of lanthanum strontium manganite (LSM), lanthanum calcium manganite (LCM), lanthanum strontium cobalt ferrite (LSCF), lanthanum strontium ferrite (LSF), lanthanum strontium manganese ferrite (LSMF) and lanthanum strontium chromite (LSCr), and lanthanum strontium cobaltite (LSCo).

5 . The SOFC of claim 2 , wherein the cathode electrode contains around 10-90 wt % of the ceria-based ceramic component and around 10-90 wt % of the electrically conductive component.

6 . The SOFC of claim 5 , wherein the cathode electrode contains around 55-75 wt % of the ceria-based ceramic component and around 25-45 wt % of the electrically conductive component.

7 . The SOFC of claim 6 , wherein the cathode electrode contains around 70 wt % of the ceria-based ceramic component and around 30 wt % of the electrically conductive component.

8 . The SOFC of claim 5 , wherein the cathode further comprises at least one of an additional catalyst material comprising one or more of cobalt, platinum, or ruthenium, and a sintering aid comprising one or more of cobalt, magnesium, nickel, iron, or copper.

9 . The SOFC of claim 8 , wherein the cathode contains less than 0.5 wt % of the at least one of the additional catalyst material and the sintering aid.

10 . A solid oxide fuel cell (SOFC), comprising:
a solid oxide electrolyte comprising a zirconia-based ceramic; an anode electrode; and a cathode electrode comprising an electrically conductive component and an ionically conductive component, wherein the ionically conductive component comprises a zirconia-based ceramic containing scandia and at least one of ceria, ytterbia and yttria.

11 . The SOFC of claim 10 , wherein the cathode electrode contains around 10-90 wt % of each of the ionically conductive component and around 10-90 wt % of the electrically conductive component.

12 . The SOFC of claim 10 , wherein the ionically conductive component comprises scandia-stabilized zirconia (SSZ), ceria, and at least one of yttria and ytterbia, and wherein the solid oxide electrolyte comprises scandia stabilized zirconia.

13 . The SOFC of claim 10 , wherein the ionically conductive component and the solid oxide electrolyte each comprise a formula (ZrO 2 ) 1-w-x-z (Sc 2 O 3 ) w (CeO 2 ) x (Y 2 O 3 ) a (Yb 2 O 3 ) b , wherein 0.09≦w≦0.11, 0<x≦0.0125, a+b=z, and 0.0025≦z≦0.0125.

14 . The SOFC of claim 13 , wherein 0.009<x≦0.011, 0.009≦z≦0.011, and wherein the ionically conductive component and the solid oxide electrolyte have the same composition.

15 . The SOFC of claim 10 , wherein the electrically conductive component comprises an electrically conductive ceramic selected from the group consisting of lanthanum strontium manganite (LSM), lanthanum calcium manganite (LCM), lanthanum strontium cobalt ferrite (LSCF), lanthanum strontium ferrite (LSF), lanthanum strontium manganese ferrite (LSMF) and lanthanum strontium chromite (LSCr), and lanthanum strontium cobaltite (LSCo).

16 . The SOFC of claim 10 , wherein the cathode electrode further comprises 0.5 wt % or less at least one of an additional catalyst material comprising one or more of cobalt, platinum, or ruthenium, and a sintering aid comprising one or more of cobalt, magnesium, nickel, iron, or copper.

17 . The SOFC of claim 10 , the cathode electrode has a graded composition where a ratio of the ionically conductive component to electrically conductive component in the cathode electrode decreases form an electrolyte-cathode interface towards a free surface of the cathode electrode.

18 . A method of operating a solid oxide fuel cell comprising a zirconia-based electrolyte and a cathode electrode containing an electrically conductive component and an ionically conductive component, the method comprising operating the solid oxide fuel cell at 800-850° C. for at least 4000 hrs such that the SOFC does not experience a voltage degradation of greater than 15%.

19 . The method of claim 18 , wherein the ionically conductive component comprises a ceria-doped ceramic and the electrically conductive component comprises a perovskite ceramic.

20 . The method of claim 18 , wherein the ionically conductive component comprises scandia-stabilized zirconia (SSZ)-based ceramic containing scandia, ceria, and at least one of ytterbia and yttria, and the electrically conductive component comprises a perovskite ceramic.

Assignees

• Bloom Energy Corp

Inventors

• Leming Andres
• El Batawi Emad
• Gasda Michael
• Armstrong Tad
• Wilson James

Classifications

• H01M2004/8689

  Positive electrodes · CPC title

• H01M2300/0077

  based on zirconium oxide · CPC title

• H01M4/9033 Primary

  Complex oxides, optionally doped, of the type M1MeO3, M1 being an alkaline earth metal or a rare earth, Me being a metal, e.g. perovskites · CPC title

• H01M4/9066

  of metal-ceramic composites or mixtures, e.g. cermets · CPC title

• H01M4/92

  Metals of platinum group (H01M4/94 {, H01M4/9058} take precedence) · CPC title