Composite electrolyte for a solid oxide fuel cell, exhaust gas probe or high-temperature gas sensor

Abstract

This relates to a sinterable composite electrolyte compound, a sintered composite electrolyte, a method for manufacturing a sintered composite electrolyte and the use of the sintered composite electrolyte in a fuel cell, preferably a solid oxide fuel cell, an exhaust gas probe or a high-temperature gas sensor, and a fuel cell, preferably a solid oxide fuel cell, exhaust gas probe or high-temperature gas sensor containing the sintered composite electrolyte.

Claims

1. A sinterable composite electrolyte compound comprising: a) an electrolyte selected from the group consisting of 8YSZ, 10Sc1CeSZ, 10Sc1AlSZ, 10Sc2YbSZ, 3YSZ, 6ScSZ and mixtures thereof, and b) a material distributed in the electrolyte in a quantity from 0.1 to 15.0% by weight relative to the total weight of the electrolyte, wherein the material has an average particle size d.sub.50 from 1 to 80 nm and comprises at least two materials selected from the group consisting of 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1AlSZ, 10Sc2YbSZ and mixtures thereof.

2. The sinterable composite electrolyte compound according to claim 1, wherein the sinterable composite electrolyte compound comprises the electrolyte in a quantity from 85 to 99.9% by weight, relative to the total weight of the compound.

3. The sinterable composite electrolyte compound according to claim 1, wherein the electrolyte has an average particle size d.sub.50 from 0.5 to 5 m and the electrolyte has a particle size d.sub.80 of less than 5 m.

4. The sinterable composite electrolyte compound according claim 1, wherein the electrolyte has an average particle size d.sub.50 from 0.5 to 5 m or the electrolyte has a particle size d.sub.80 of less than 5 m.

5. The sinterable composite electrolyte compound according to claim 1, wherein the material distributed in the electrolyte comprises at least three materials selected from the group consisting of 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1AlSZ, 10Sc2YbSZ and mixtures thereof.

6. The sinterable composite electrolyte compound according to claim 1, wherein the sinterable composite electrolyte compound comprises the material distributed in the electrolyte in a quantity from 0.2 to 10.0% by weight relative to the total weight of the electrolyte.

7. The sinterable composite electrolyte compound according to claim 1, wherein the material distributed in the electrolyte has an average particle size d.sub.50 from 2 to 50 nm.

8. The sinterable composite electrolyte compound according to claim 1, wherein the material distributed in the electrolyte is present in the form of nanopowder or nanofibres.

9. The sinterable composite electrolyte compound according to claim 1, wherein the sinterable composite electrolyte compound additionally comprises a further material having an average particle size d.sub.50 from 1 to 5 m.

10. The sinterable composite electrolyte compound according to claim 9, wherein the sinterable composite electrolyte compound comprises the further material in a quantity from 0.1 to 1.0% by weight relative to the total weight of the electrolyte.

11. A sintered composite electrolyte comprising the sinterable composite electrolyte compound according to claim 1.

12. A method for manufacturing a sintered composite electrolyte having a density greater than or equal to 5.9 g/cm.sup.3, comprising the steps of: preparing a sinterable composite electrolyte compound comprised of an electrolyte selected from the group consisting of 8YSZ, 10Sc1CeSZ, 10Sc1AlSZ, 10Sc2YbSZ, 3YSZ, 6ScSZ and mixtures thereof, and a material distributed in the electrolyte in a quantity from 0.1 to 15.0% by weight relative to the total weight of the electrolyte, wherein the material has an average particle size d.sub.50 from 1 to 80 nm and comprises at least two materials selected from the group consisting of 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1AlSZ, 10Sc2YbSZ and mixtures thereof, sintering the sinterable composite electrolyte compound at temperatures less than or equal to 1300 C. and for a bonding time less than 5 hours.

13. A fuel cell, exhaust gas probe or high-temperature gas sensor containing a sintered composite electrolyte wherein the sintered composite electrolyte has a density greater than or equal to 5.9 g/cm.sup.3 and comprises a sinterable composite electrolyte compound comprising: a) an electrolyte selected from the group consisting of 8YSZ, 10Sc1CeSZ, 10Sc1AlSZ, 10Sc2YbSZ, 3YSZ, 6ScSZ and mixtures thereof, and b) a material distributed in the electrolyte in a quantity from 0.1 to 15.0% by weight relative to the total weight of the electrolyte, wherein the material has an average particle size d.sub.50 from 1 to 80 nm and comprises at least two materials selected from the group consisting of 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1AlSZ, 10Sc2YbSZ, and mixtures thereof.

14. The sintered composite electrolyte according to claim 11, wherein the sintered composite electrolyte has a density greater than or equal to 5.9 g/cm.sup.3.

Description

DETAILED DESCRIPTION

(1) The following detailed description is merely exemplary in nature and is not intended to limit the disclosed embodiments or the application and uses thereof. Furthermore, there is no intention to be bound by any theory presented in the preceding background detailed description.

(2) The present embodiment relates to a sinterable composite electrolyte compound comprising an electrolyte selected from the group consisting of 8YSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ, 3YSZ, 6ScSZ and mixtures thereof, and at least one material distributed in the electrolyte in a quantity from 0.1 to 15.0% by weight, relative to the total weight of the electrolyte, wherein the material has an average particle size d.sub.50 from 1 to 80 nm.

(3) The term sinterable means that fine-grained materials of metal and/or metal oxide are mixed and compacted at elevated temperature, wherein the temperatures remain below the melting temperature of the main component.

(4) On requirement of the present embodiment is that the sinterable composite electrolyte compound comprise an electrolyte selected from the group consisting of 8YSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ, 3YSZ, 6ScSZ and mixtures thereof.

(5) The electrolyte is the main component of the sinterable composite electrolyte compound.

(6) In one embodiment, the sinterable composite electrolyte compound comprises 8YSZ, 10Sc1CeSZ, 10Sc1A1SZ or 10Sc2YbSZ, 3YSZ, 6ScSZ as the electrolyte. For example, the sinterable composite electrolyte compound comprises 8YSZ or 10Sc1CeSZ as the electrolyte. The sinterable composite electrolyte compound preferably comprises 10Sc1CeSZ as the electrolyte.

(7) In one embodiment, the electrolyte is present in the cubic or tetragonal crystalline phase. The electrolyte is preferably present in the cubic crystalline phase.

(8) In addition or alternatively thereto, the electrolyte exhibits sufficient mechanical stability. For example, the electrolyte exhibits mechanical stability in the order of 170 to 550 MPa or 170 to 350 MPa. The electrolyte preferably exhibits mechanical stability in the order of 180 to 250 MPa. Alternatively, the electrolyte exhibits mechanical stability in the order of 210 to 340 MPa.

(9) In one embodiment, the electrolyte has a conductivity in the order of 0.07 to 0.25 S/cm or 0.07 to 0.23 S/cm. The electrolyte preferably has a conductivity in the order of 0.07 to 0.09 S/cm. Alternatively, the electrolyte has a conductivity in the order of 0.17 to 0.23 S/cm.

(10) As was stated earlier, the electrolyte is the main component of the sinterable composite electrolyte compound. Accordingly, the sinterable composite electrolyte compound comprises the electrolyte in a quantity from 85 to 99.9% by weight relative to the total weight of the compound. Alternatively, the sinterable composite electrolyte compound comprises the electrolyte in a quantity from 90 to 99.9% by weight relative to the total weight of the compound. For example, the sinterable composite electrolyte compound comprises the electrolyte in a quantity from 90 to 95% by weight relative to the total weight of the compound.

(11) In order to obtain a sinterable composite electrolyte compound with sufficient mechanical stability, it is advantageous if the electrolyte has a certain average particle size.

(12) In particular, it is advantageous if the electrolyte has an average particle size d.sub.50 from 0.5 to 5 m. For example, the electrolyte has an average particle size d.sub.50 from 0.7 to 2.5 m. The electrolyte preferably has an average particle size d.sub.50 from 0.9 to 1.5 m.

(13) Unless stated otherwise, all particle sizes were determined by laser scattering. Devices and methods for determining particle sizes by means of laser scattering are known to a person skilled in the art.

(14) In addition or alternatively thereto, the electrolyte has a particle size d.sub.80<5 m.

(15) In order to lower the sintering temperature of the sinterable composite electrolyte compound, it is a requirement of the present embodiment that the sinterable composite electrolyte compound contains at least one material distributed in the electrolyte in a quantity from 0.1 to 15.0% by weight relative to the total weight of the electrolyte, wherein the material has an average particle size d.sub.50 from 1 to 80 nm.

(16) It is particularly advantageous for the sinterable composite electrolyte compound if the at least one material distributed in the electrolyte is dispersed homogeneously therein.

(17) Alternatively, the least one material distributed in the electrolyte may be dispersed inhomogeneously therein.

(18) The least one material distributed in the electrolyte is preferably dispersed homogeneously in the electrolyte.

(19) The sinterable composite electrolyte compound preferably comprises the at least one material distributed in the electrolyte in a quantity from 0.1 to 10.0% by weight, or from 0.1 to 7.5% by weight relative to the total weight of the electrolyte.

(20) In principle, any material of metal and/or metal oxide that has an average particle size d.sub.50 from 1 to 80 nm may be used. However, the at least one material distributed in the electrolyte is preferably selected from the group comprising 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof.

(21) In one embodiment, the sinterable composite electrolyte compound contains a material distributed in the electrolyte that is selected from the group comprising 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof.

(22) If the sinterable composite electrolyte compound is a material distributed in the electrolyte and selected from the group comprising 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof, the material distributed in the electrolyte is preferably 8YSZ.

(23) Alternatively, the material distributed in the electrolyte contains at least two materials selected from the group comprising 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof. For example, the material distributed in the electrolyte comprises two materials selected from the group consisting of 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof.

(24) If the material distributed in the electrolyte comprises at least two, preferably two materials selected from the group comprising 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof, the material distributed in the electrolyte preferably comprises a mixture of MgO and Al.sub.2O.sub.3.

(25) If the at least one material distributed in the electrolyte is present as a mixture of MgO and Al.sub.2O.sub.3, the mixture preferably comprises the mixture of MgO and Al.sub.2O.sub.3 in a certain weight ratio. For example, MgO and Al.sub.2O.sub.3 are present in a weight ratio (Wgt[MgO]/Wgt[Al.sub.2O.sub.3]) from 10:1 to 1:10. MgO and Al.sub.2O.sub.3 are preferably present in a weight ratio (Wgt[MgO]/Wgt[Al.sub.2O.sub.3]) from 5:1 to 1:5. In one embodiment, MgO and Al.sub.2O.sub.3 are present in a weight ratio (Wgt[MgO]/Wgt[Al.sub.2O.sub.3]) of approximately 1:1.

(26) Alternatively, the material distributed in the electrolyte comprises at least three materials selected from the group comprising 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof. For example, the material distributed in the electrolyte comprises three materials selected from the group comprising 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof.

(27) If the material distributed in the electrolyte comprises at least three, preferably three materials selected from the group comprising 8YSZ, Al.sub.2O.sub.3, MgO, Al, Mg, 3YSZ, 6ScSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ and mixtures thereof, the material distributed in the electrolyte preferably comprises a mixture of 8YSZ, Al.sub.2O.sub.3 and MgO.

(28) If the at least one material distributed in the electrolyte is present as a mixture of 8YSZ, Al.sub.2O.sub.3 and MgO, the mixture preferably comprises 8YSZ, Al.sub.2O.sub.3 and MgO in a certain weight ratio. For example, 8YSZ, Al.sub.2O.sub.3 and MgO are present in a weight ratio (Wgt[8YSZ]/Wgt[Al.sub.2O.sub.3]/Wgt[MgO]) from 20:1:1 to 1:1:1. 8YSZ, Al.sub.2O.sub.3 and MgO are preferably present in a weight ratio (Wgt[8YSZ]/Wgt[Al.sub.2O.sub.3]/Wgt[MgO]) from 15:1:1 to 5:1:1. In one embodiment, 8YSZ, Al.sub.2O.sub.3 and MgO are present in a weight ratio (Wgt[8YSZ]/Wgt[Al.sub.2O.sub.3]/Wgt[MgO]) of approximately 10:1:1.

(29) Therefore, the sinterable composite electrolyte compound comprises, preferably contains an electrolyte selected from the group consisting of 8YSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ, 3YSZ, 6ScSZ and mixtures thereof, and at least one, preferably at least two, even more preferably at least three, material/s distributed in the electrolyte in a quantity from 0.1 to 15.0% by weight relative to the total weight of the electrolyte, wherein the material/s has/have an average particle size d.sub.50 from 1 to 80 nm.

(30) In one embodiment the sinterable composite electrolyte compound therefore comprises, preferably contains an electrolyte selected from the group consisting of 8YSZ, 10Sc1CeSZ, 10Sc1A1SZ, 10Sc2YbSZ, 3YSZ, 6ScSZ and mixtures thereof, and one, preferably two, more preferably three, materials distributed in the electrolyte in a quantity from 0.1 to 15.0% by weight relative to the total weight of the electrolyte, wherein the material/s has/have an average particle size d.sub.50 from 1 to 80 nm.

(31) The sinterable composite electrolyte compound may comprise the at least one material distributed in the electrolyte in various quantities.

(32) For example, the sinterable composite electrolyte compound preferably comprises the at least one material distributed in the electrolyte in a quantity from 2.5 to 10.0% by weight or from 4.0 to 7.5% by weight relative to the total weight of the electrolyte, if the at least one material distributed in the electrolyte is 8YSZ.

(33) If the material distributed in the electrolyte comprises at least one material selected from the group comprising Al.sub.2O.sub.3, MgO, Al, Mg and mixtures thereof, the sinterable composite electrolyte compound comprises the at least one material that is distributed in the electrolyte preferably in a quantity von 0.2 to <2.5% by weight or from 0.3 to 1.5% by weight relative to the total weight of the electrolyte.

(34) In one embodiment, the at least one material distributed in the electrolyte has an average particle size d.sub.50 from 2 to 50 nm. For example, the at least one material distributed in the electrolyte has an average particle size d.sub.50 from 2 to 10 nm or from 5 to 10 nm.

(35) The at least one material distributed in the electrolyte in present for example in the form of nanopowder or nanofibres.

(36) In one embodiment, the sinterable composite electrolyte compound may comprise a further material with an average particle size d.sub.50 from 1 to 5 m. This is particularly advantageous for improving the sintering behaviour of the composite electrolyte.

(37) For example, the sinterable composite electrolyte compound comprises a further material with an average particle size d.sub.50 from 1 to 3 m or from 1.5 to 2.5 m.

(38) If the sinterable composite electrolyte compound comprises a further material, the further material is preferably MgO or Al.sub.2O.sub.3.

(39) In one embodiment, the sinterable composite electrolyte compound preferably comprises the further material in a quantity from 0.1 to 1.0% by weight relative to the total weight of the electrolyte. For example, the sinterable composite electrolyte compound comprises the further material in a quantity from 0.1 to 0.8% by weight or from 0.2 to 0.8% by weight relative to that total weight of the electrolyte. The sinterable composite electrolyte compound preferably comprises the further material in a quantity from 0.3 to 0.7% by weight, or from 0.4 to 0.6% by weight relative to the total weight of the electrolyte.

(40) Based on the advantages that the sinterable composite electrolyte compound offers, the present embodiment also relates to a sintered composite electrolyte that comprises the sinterable composite electrolyte compound as described in this document.

(41) The sinterable composite electrolyte compound offers the advantage that it can be processed by Additive Layer Manufacturing (ALM) or non-conventional 3D manufacturing processes such as weaving technology. The sinterable composite electrolyte compound further offers the advantage that, when sintered at sintering temperatures T.sub.sinter1300 C. and for a bonding time t.sub.bond<5 h the sinterable composite electrolyte compound results in an electrolyte composite that is gas-impermeable and has a density of 5.9 g/cm.sup.3, and at the same time is capable of thin dimensioning.

(42) Accordingly, the sintered composite electrolyte preferably has a density 5.9 g/cm.sup.3. For example, the sintered composite electrolyte preferably has a density from 6.0 g/cm.sup.3 to 6.5 g/cm.sup.3 or from 6.0 g/cm.sup.3 to 6.3 g/cm.sup.3.

(43) A further aspect of the present embodiment relates to a method for manufacturing a sintered composite electrolyte, as described in the present document, comprising the steps of preparing a sinterable composite electrolyte compound as described herein, and sintering the sinterable composite electrolyte compound at temperatures 1300 C. and for a bonding time <5 h.

(44) The sinterable composite electrolyte compound according to the embodiment may generally be prepared by mixing the electrolyte and the at least one material distributed in the electrolyte together. Sintering is carried out at temperature 1300 C. or from 800 to 1300 C., for example from 900 to 1300 C., preferably for a total of <5 h or for 3 to <5 h. The sintering may be carried out in a single, continuous process or in several different, chronologically separate steps. The sintering preferably takes place in a single, continuous process. In one embodiment, sintering is carried out with different temperature ramps.

(45) A further advantage is that the sinterable composite electrolyte compound according to the embodiment has good ion-conducting capability (O.sup.2) in the sintered state, and therefore can be used for a fuel cell, preferably a solid oxide fuel cell, or an exhaust gas probe or a high-temperature gas sensor (>500 C.).

(46) Based on the advantages that the sinterable composite electrolyte offers, the present embodiment also relates to the use of the sintered composite electrolyte as described in this document in a fuel cell, preferably a solid oxide fuel cell, an exhaust gas probe or a high-temperature gas sensor.

(47) A further aspect of the present embodiment thus relates to a fuel cell, preferably a solid oxide fuel cell, an exhaust gas probe or a high-temperature gas sensor containing the sintered composite electrolyte as described herein.

(48) While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the embodiment in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the embodiment as set forth in the appended claims and their legal equivalents.