Nonazeotropic terpineol-based spray suspensions for the deposition of electrolytes and electrodes and electrochemical cells including the same

Abstract

A family of spray suspensions for aerosol deposition of green ceramic layers that subsequently can be sintered to produce both dense and porous ceramic layers. The suspensions comprise a nonazeotropic solvent mixture, a ceramic powder, a dispersant, and a an organic binder. The invention also includes methods for depositing coatings of these ceramic suspensions on a substrate, either singly or sequentially, to form electrochemically efficient multilayer structures that can be economically co-sintered. The suspensions and deposition approach allow formation of thin layers of varying microstructure and composition in the sintered state. The suspensions and deposition approach are likely to be useful in the fabrication of electrochemical devices.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and further objects of the invention will become apparent from the following detailed description.

FIG. 1 is a secondary electron image scanning electron microscope (SEM) micrograph of an electrolyte-coated cathode tube without interlayer sintered at 1300° C.

FIG. 2 is a backscatter image SEM micrograph of the electrolyte coated cathode tube of FIG. 1.

FIG. 3 is a secondary electron image SEM micrograph of an electrolyte coated cathode tube with LSM/GDC interlayer sintered at 1300° C.

FIG. 4 is a backscatter image SEM micrograph of the electrolyte coated cathode tube of FIG. 3.

FIG. 5 is a secondary electron image SEM micrograph of an electrolyte-coated cathode tube with LSM/GDC interlayer sintered at 1350° C.

FIG. 6 is a backscatter image SEM micrograph of the electrolyte coated cathode tube of FIG. 5.

FIG. 7 is an SEM micrograph of an electrolyte-coated anode tube sintered for two hours at 1300° C.

FIG. 8 is an SEM micrograph of an electrolyte coated anode tube identical to the tube of FIG. 7 sintered for two hours at 1350° C.

FIG. 9 is an SEM micrograph of an electrolyte coated anode tube identical to the tube of FIG. 7 sintered for two hours at 1400° C.

FIG. 10 is a secondary electron image SEM micrograph of a current-carrying anode support tube with multiple layers deposited by aerosol spraying (active anode layer, electrolyte, active cathode interlayer, and current collector cathode layer) and then sintered at 1350° C.

FIG. 11 is a backscatter image SEM micrograph of the current-carrying anode support tube of FIG. 10.

Claims

1. A ceramic spray suspension, comprising: a minority terpineol-based solvent;a majority organic solvent having a vapor pressure higher than the vapor pressure of terpineol;an organic binder;a dispersant; anda powdered ceramic composition selected from an electrolyte material and an electrode material.

2. The ceramic spray suspension of claim 1, wherein the terpineol-based solvent comprises terpineol.

3. The ceramic spray suspension of claim 1, wherein the binder comprises ethyl cellulose.

4. The ceramic spray suspension of claim 1, wherein the ceramic composition comprises an electrolyte material selected from a stabilized zirconia composition, a doped ceria composition, a doped lanthanum gallate, a doped alkaline earth cerate, a doped alkaline earth zirconate, a bismuth oxide, and mixtures thereof.

5. The ceramic spray suspension of claim 1, wherein the ceramic material comprises an electrode material selected from a nickel oxide/doped zirconia composite, a nickel oxide doped ceria, a mixture of nickel oxide/doped ceria materials, a lanthanum strontium manganite, a lanthanum strontium ferrite, a lanthanum strontium nickelate, a lanthanum strontium cobaltite, and mixtures thereof.

6. The ceramic suspension of claim 1, wherein the majority solvent is selected from acetone and a non-terpineol alcohol.

7. A method of coating a porous substrate, the method comprising the steps of: providing a porous substrate;applying a coating of a ceramic spray suspension according to claim 1 to the substrate;applying a second coating of the ceramic spray suspension to the coated substrate; andco-sintering the coated substrate.

8. The method of claim 7, wherein the powdered ceramic composition is an electrolyte material.

9. The method of claim 7, wherein the coating steps are carried out by spray coating.

10. The method of claim 9, wherein the ceramic suspension is applied at a thickness sufficient to produce a coating at least 15 microns thick after sintering.

11. A method of coating a previously coated substrate, the method comprising the steps of: providing a coated substrate;applying a coating of a ceramic spray suspension according to claim 1 to the coated substrate.

12. The method of claim 11, wherein the coating step is carried out by spray coating.

13. A method of coating a porous ceramic substrate, the method comprising the steps of: providing a porous ceramic substrate;applying a first coating of a ceramic suspension according to claim 1 to the substrate;applying a second coating of a ceramic suspension according to claim 1 to the coated substrate; andco-sintering the coated substrate.

14. The method of claim 13, wherein the powdered ceramic composition of the first and second ceramic suspensions each comprises an electrolyte material and the step of applying the second coating is carried out while the first coating is wet.

15. The method of claim 13, wherein the powdered ceramic composition of the first and second ceramic suspensions each comprises an electrode material and the step of applying the second coating is carried out while the first coating is wet.

16. The method of claim 13, wherein the powdered ceramic composition of the first ceramic suspension comprises an electrode material, the powdered ceramic composition of the second ceramic suspension comprises an electrolyte material, and the step of applying the second coating is carried out after the first coating has dried.

17. The method of claim 13, wherein the powdered ceramic composition of the first ceramic suspension comprises an electrode material, the powdered ceramic composition of the second ceramic suspension comprises an electrolyte material, and the step of applying the second coating is carried out after the first coating has dried and been fired.

18. A method of coating a porous electrode, the method comprising the steps of: providing a porous electrode;applying a coating of a ceramic suspension according to claim 1 to the substrate, the powdered ceramic composition comprising an electrode interlayer material having a polarity corresponding to the polarity of the porous electrode;drying the coated substrate;applying a coating of a second ceramic suspension according to claim 1 to the coated substrate, the powdered ceramic composition of the second suspension comprising an electrolyte material; andco-sintering the coated substrate.

19. The method of claim 18, wherein the coating steps are carried out by spray coating and the electrolyte suspension and the electrode suspension each is applied at a thickness sufficient to produce a layer at least 15 microns thick after sintering.

20. The method of claim 18, further comprising the step of: applying a second coating of the second suspension to the electrolyte coating before co-sintering the coated substrate.

21. The method of claim 18, further comprising the steps of: applying a second coating of the second suspension to the electrolyte coating after co-sintering the coated substrate; andsintering the re-coated substrate.

22. A method of making an electrochemical cell, the method comprising the steps of: providing a porous electrode;applying a coating of a ceramic suspension according to claim 1 to the electrode, the powdered ceramic composition comprising an electrode interlayer material having a polarity corresponding to the polarity of the porous electrode;drying the coated electrode;applying a coating of a second ceramic suspension according to claim 1 to the coated electrode, the powdered ceramic composition of the second suspension comprising an electrolyte material;drying the electrolyte-coated electrode;applying a coating of a third ceramic suspension according to claim 1 to the electrolyte-coated electrode, the powdered ceramic composition of the third suspension comprising an electrode interlayer material having a polarity opposite the polarity of the porous electrode;applying a coating of a fourth ceramic suspension according to claim 1 to the electrode interlayer-coated electrode, the powdered ceramic composition of the fourth suspension comprising a current-carrying electrode material having a polarity opposite the polarity of the porous electrode; andco-sintering the coated electrode.

23. The method of claim 22, further comprising the step of: selecting an unsintered porous ceramic electrode.