ELECTROLYTE SEPARATOR AND METHOD OF MAKING THE ELECTROLYTE SEPARATOR

• US 20110236743A1
• Filed: 03/24/2010
• Published: 09/29/2011
• Est. Priority Date: 03/24/2010
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Kumar, Sundeep, Nayak, Mohandas, Basak, Arunabh, Krishna, Kalaga Murali, Rahmane, Mohamed, Saha, Atanu
• Granted Patent: US 9,368,774 B2
• Time in Patent Office: Days
• US Class Current: 429/144
• CPC Class Codes: H01M 10/39 working at high temperature
• CPC Class Codes: H01M 50/434 Ceramics
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

An electrolyte separator structure is provided. The electrolyte separator structure comprises a graded integral structure, wherein the structure comprises an ion-conducting first ceramic at a first end and an electrically insulating second ceramic at a second end, wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is less than or equal to about 5 parts per million per degrees Centigrade, and wherein at least one of the first ceramic or the second ceramic comprises a strengthening agent. Method of making the ion-separator structure is provided. Electrochemical cells comprising the ion-separator structure and method of making the electrochemical cell using the ion-separator structure are also provided.

Claims

1. An electrolyte separator structure comprising:

a graded integral structure, wherein the graded integral structure comprises an ion-conducting first ceramic at a first end and an electrically insulating second ceramic at a second end;

wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is less than or equal to about 5 parts per million per degrees Centigrade; and

wherein at least one of the first ceramic or the second ceramic comprises a strengthening agent.

2. The electrolyte separator structure of claim 1, wherein the ion-conducting first ceramic comprises beta-alumina.

3. The electrolyte separator structure of claim 1, wherein the electrically insulating second ceramic comprises one or more of alpha-alumina, yttria, yttria stabilized zirconia, yttrium aluminum garnet, magnesia alumina spinel, and yttrium aluminate perovskite.

4. The electrolyte separator structure of claim 1, wherein about 80 percent to about 99 percent of the graded integral structure, based on the total length of the graded integral structure, comprises the ion-conducting first ceramic.

5. The electrolyte separator structure of claim 1, wherein about 1 percent to about 20 percent of the graded integral structure, based on the total length of the graded integral structure, comprises the electrically insulating second ceramic.

6. The electrolyte separator structure of claim 1, wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is in a range from about 0.001 parts per million per degrees Centigrade to about 5 parts per million per degrees Centigrade.

7. The electrolyte separator structure of claim 1, wherein both the first ceramic and the second ceramic comprise a strengthening agent.

8. The electrolyte separator structure of claim 1, wherein the strengthening agent comprises an oxide, a nitride, or a carbide of at least one element selected from the group consisting of group IIIA elements, group IIIB elements, group IVB elements, and group IVB elements.

9. The electrolyte separator structure of claim 1, wherein the strengthening agent is present in the first ceramic in a range from about 1 volume percent to about 50 volume percent based on the volume of the first ceramic.

10. The electrolyte separator structure of claim 1, wherein the strengthening agent is present in the second ceramic in a range from about 1 volume percent to about 50 volume percent based on the volume of the second ceramic.

11. The electrolyte separator structure of claim 1, wherein the ratio of the amount of the strengthening agent present in the first ceramic to the amount of the strengthening agent in the second ceramic is in a range from about 1:

0.2 to about 1;

5.

12. A method comprising;

selecting an ion-conducting first ceramic and an electrically insulating second ceramic;

wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is less than or equal to about 5 parts per million per degrees Centigrade, and wherein at least one of the first ceramic or the second ceramic comprises a strengthening agent;

partially filling a mold with a first material comprising the ion-conducting first ceramic and filling the remaining portion of the mold with a second material comprising the electrically insulating second ceramic;

applying a pressure to the mold to form a green body;

sintering the green body at a temperature to form a graded integral structure comprising the ion-conducting first ceramic at a first end and the electrically insulating second ceramic at a second end.

13. The method of claim 12, wherein the strengthening agent comprises an oxide, a nitride, or a carbide of at least one element selected from the group consisting of group IIIA elements, group IIIB elements, group IVB elements, and group IVB elements.

14. The method of claim 12, wherein the strengthening agent comprises one or more of zirconia, titania, silicon carbide, boron carbide, and silicon nitride.

15. The method of claim 12, wherein the first material comprises beta-alumina.

16. The method of claim 12, wherein the first material is a powder having an average particle size in a range from about 0.1 micrometers to about 10 micrometers.

17. The method of claim 12, wherein the second material comprises one or more of alpha-alumina, yttria, yttria stabilized zirconia, yttrium aluminum garnet, magnesia alumina spinel, and yttrium aluminate perovskite.

18. The method of claim 12, wherein the second material is a powder having an average particle size in a range from about 0.02 micrometers to about 10 micrometers.

19. The method of claim 12, wherein the strengthening agent has an average particle size in a range from about 0.02 micrometers to about 10 micrometers and an aspect ratio in the range from about 1 to about 10.

20. The method of claim 12, wherein the strengthening agent is present in the first material in a range from about 1 volume percent to about 50 volume percent based on the volume of the first material.

21. The method of claim 12, wherein the strengthening agent is present in the second material in a range from about 1 volume percent to about 50 volume percent based on the volume of the second material.

22. The method of claim 12, wherein about 80 percent to about 99 percent of the mold based on a total length of the mold is filled with the first material and about 1 percent to about 20 percent of the mold based on the total length of the mold is filled with the second material.

23. The method of claim 12, wherein forming the green body comprises uni-axial pressing, iso-static pressing, slip casting, tape casting, or pressure filtering.

24. The method of claim 12, wherein the pressure applied for forming the green body is in a range from about 2×

10⁷ Newtons per square meter to about 4×

10⁷ Newtons per square meter.

25. The method of claim 12, wherein forming the green body is performed at a temperature in a range from about 1200 degrees Centigrade to about 1800 degrees Centigrade.

26. An electrochemical cell, comprising:

an electrolyte separator structure comprising a graded integral structure, wherein the graded integral structure comprises an ion-conducting first ceramic at a first end and an electrically insulating second ceramic at a second end;

wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is less than or equal to about 5 parts per million per degrees Centigrade; and

wherein at least one of the first ceramic or the second ceramic comprises a strengthening agent.

27. The electrochemical cell of claim 26, wherein the ion-conducting first ceramic comprises beta-alumina.

28. The electrochemical cell of claim 26, wherein the electrically insulating second ceramic comprises alpha-alumina.

29. The electrochemical cell of claim 26, wherein about 80 percent to about 99 percent of the structure, based on the total length of the structure, comprises the ion-conducting first ceramic.

30. The electrochemical cell of claim 26, wherein about 1 percent to about 20 percent of the structure, based on the total length of the structure, comprises the electrically insulating second ceramic.

31. The electrochemical cell of claim 26, wherein the end of the structure comprising the first ceramic is closed and the end comprising the second ceramic is open.

32. An electrochemical cell comprising;

an electrolyte separator structure comprising a graded integral structure comprising a closed first end and an open second end, wherein the graded integral structure comprises an ion-conducting first ceramic at the closed first end and an electrically insulating second ceramic at the open second end;

wherein the open second end of the graded integral structure is fitted with a collar, the collar comprising a cermet layer, and a layer of an electrically insulating ceramic;

wherein the electrically insulating ceramic in the collar is disposed at the open second end of the graded integral structure;

wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is less than or equal to about 5 parts per million per degrees Centigrade; and

wherein at least one of the first ceramic or the second ceramic comprises a strengthening agent.

33. The electrochemical cell of claim 32, wherein the collar further comprises a metal contact layer disposed over the cermet layer.

34. The electrochemical cell of claim 32, wherein the ion-conducting first ceramic comprises beta-alumina.

35. The electrochemical cell of claim 32, wherein the electrically insulating second ceramic comprises alpha-alumina.

36. The electrochemical cell of claim 32, wherein about 80 percent to about 99 percent of the structure based on the total length of the structure, comprises the ion-conducting first ceramic.

37. The electrochemical cell of claim 32, about 1 percent to about 20 percent of the structure based on the total length of the structure, comprises the electrically insulating second ceramic.

38. The electrochemical cell of claim 32, wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is in a range from about 0.001 parts per million per degrees Centigrade to about 4 parts per million per degrees Centigrade.

39. The electrochemical cell of claim 32, wherein both the first ceramic and the second ceramic comprise a strengthening agent.

40. The electrochemical cell of claim 32, wherein the strengthening agent comprises an oxide, a nitride, or a carbide of at least one element selected from the group consisting of group IIIA elements, group IIIB elements, group IVB elements, and group IVB elements.

41. The electrochemical cell of claim 32, wherein the strengthening agent is present in the first ceramic in a range from about 1 volume percent to about 50 volume percent based on the volume of the first ceramic.

42. The electrochemical cell of claim 32, wherein the strengthening agent is present in the second ceramic in a range from about 1 volume percent to about 50 volume percent based on the volume of the second ceramic.

43. The electrochemical cell of claim 32, wherein the ratio of the amount of the strengthening agent present in the first ceramic to the amount of the strengthening agent in the second ceramic is in a range from about 1:

0.2 to about 1;

5.

44. A method comprising;

forming a graded integral structure comprising an ion-conducting first ceramic and an electrically insulating second ceramic;

wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is less than or equal to about 5 parts per million per degrees Centigrade, wherein at least one of the first ceramic or the second ceramic comprises a strengthening agent;

wherein the graded integral structure comprises a closed first end and an open second end, wherein the structure comprises an ion-conducting first ceramic at the first end and an electrically insulating second ceramic at the second end;

wherein the second end of the graded integral structure is fitted with a collar, the collar comprising a cermet layer, and a layer of an electrically insulating ceramic;

sintering the graded integral structure and the collar at a temperature to form a joint between the layer of the electrically insulating ceramic in the collar and the electrically insulating second ceramic at the second end.

45. The method of claim 44, wherein forming the graded integral structure comprises:

selecting an ion-conducting first ceramic and an electrically insulating second ceramic;

wherein the difference in the coefficient of thermal expansion of the ion-conducting first ceramic and the electrically insulating second ceramic is less than or equal to about 5 parts per million per degrees Centigrade, and wherein at least one of the first ceramic or the second ceramic comprises a strengthening agent;

partially filling a mold with a first material comprising the ion-conducting first ceramic and filling the remaining portion of the mold with a second material comprising the electrically insulating second ceramic;

applying a pressure to the mold to form a green body; and

sintering the green body at a temperature to form a graded integral structure comprising the ion-conducting first ceramic at a first end and the electrically insulating second ceramic at a second end.

46. The method of claim 44, wherein the strengthening agent comprises an oxide, a nitride, or a carbide of at least one element selected from the group consisting of group IIIA elements, group IIIB elements, group IVB elements, and group IVB elements.

47. The method of claim 44, wherein the first material comprises beta-alumina.

48. The method of claim 44, wherein the second material comprises alpha-alumina.

49. The method of claim 44, wherein forming the green body comprises a step of uni-axial pressing, iso-static pressing, slip casting, tape casting, or pressure filtering.

50. The method of claim 44, wherein the pressure applied for forming the green body is in a range from about 2×

10⁷ Newtons per square meter to about 4×

10⁷ Newtons per square meter.

51. The method of claim 44, wherein the temperature at which the green body is sintered is in a range from about 1200 degrees Centigrade to about 1800 degrees Centigrade.