Nanostructured ion conducting solid electrolytes

• US 5,905,000 A
• Filed: 10/30/1996
• Issued: 05/18/1999
• Est. Priority Date: 09/03/1996
• Status: Expired due to Term

• Current Assignee: PPG Industries Ohio Incorporated (Nouryon BV)
• Original Assignee: Nanomaterials Research Corp.
• Inventors: Yadav, Tapesh, Hu, Hongxing
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US08/739,257
• Time in Patent Office: 930 Days
• Field of Search: 429/33, 429/45, 204/421, 428/702
• US Class Current: 429/482
• CPC Class Codes: B01J 12/005 carried out at high temperatures, e.g. by pyrolysis
• CPC Class Codes: B01J 12/02 for obtaining at least one reaction product which, at normal temperature, is in the solid state
• CPC Class Codes: B01J 19/24 Stationary reactors without moving elements inside B01J19/08, B01J19/26 take precedence; with stationary particles B01J8/02
• CPC Class Codes: B01J 2219/00094 Jackets
• CPC Class Codes: B01J 2219/00135 Electric resistance heaters
• CPC Class Codes: B01J 2219/00155 using insulating materials or refractories
• CPC Class Codes: B01J 2219/00177 controlling the pH
• CPC Class Codes: B01J 2219/0018 controlling the conductivity
• CPC Class Codes: B01J 2219/0894 Processes carried out in the presence of a plasma
• CPC Class Codes: B22F 1/054 Nanosized particles
• CPC Class Codes: B22F 1/12 Metallic powder containing non-metallic particles containing lubricating or binding agents or organic material B22F1/10
• CPC Class Codes: B22F 2202/13 Use of plasma
• CPC Class Codes: B22F 2999/00 Aspects linked to processes or compositions used in powder metallurgy
• CPC Class Codes: B22F 9/12 starting from gaseous material
• CPC Class Codes: B29C 70/58 comprising fillers only , e.g. particles, powder, beads, flakes, spheres B29C70/025 takes precedence, agglomerating hollow spheres to produce synthetic foam B29C70/66; compounding ingredients per se C08K
• CPC Class Codes: B82B 1/00 Nanostructures formed by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: B82Y 5/00 Nanobiotechnology or nanomedicine, e.g. protein engineering or drug delivery
• CPC Class Codes: C01B 13/145 After-treatment of oxides or hydroxides, e.g. pulverising, drying, decreasing the acidity
• CPC Class Codes: C01B 19/007 : Tellurides or selenides of metals C01B19/002 takes precedence
• CPC Class Codes: C01B 21/062 : with chromium, molybdenum or tungsten
• CPC Class Codes: C01B 32/956 : Silicon carbide
• CPC Class Codes: C01B 35/04 : Metal borides
• CPC Class Codes: C01F 11/06 : of carbonates
• CPC Class Codes: C01F 5/06 : by thermal decomposition of magnesium compounds calcining magnesite or dolomite C04B2/10
• CPC Class Codes: C01G 23/006 : Alkaline earth titanates
• CPC Class Codes: C01G 41/02 : Oxides; Hydroxides
• CPC Class Codes: C01P 2002/01 : depicted by a TEM-image
• CPC Class Codes: C01P 2002/02 : Amorphous compounds
• CPC Class Codes: C01P 2002/34 : perovskite-type (ABO3)
• CPC Class Codes: C01P 2002/54 : one element only
• CPC Class Codes: C01P 2002/60 : Compounds characterised by their crystallite size
• CPC Class Codes: C01P 2002/72 : by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/03 : obtained by SEM
• CPC Class Codes: C01P 2004/04 : obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/38 : cube-like
• CPC Class Codes: C01P 2004/51 : Particles with a specific particle size distribution
• CPC Class Codes: C01P 2004/54 : Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
• CPC Class Codes: C01P 2004/61 : Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 : Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 : Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2004/82 : two phases having the same anion, e.g. both oxidic phases
• CPC Class Codes: C01P 2006/10 : Solid density
• CPC Class Codes: C01P 2006/12 : Surface area
• CPC Class Codes: C01P 2006/40 : Electric properties
• CPC Class Codes: C01P 2006/60 : Optical properties, e.g. expressed in CIELAB-values
• CPC Class Codes: C01P 2006/80 : Compositional purity
• CPC Class Codes: C04B 2/10 : Preheating, burning calcining or cooling decarbonation during burning of cement raw materials C04B7/43; obtaining CaO or MgO otherwise than by thermal decomposition of the corresponding carbonates C01F11/02, C01F5/02
• CPC Class Codes: C04B 35/62222 : obtaining ceramic coatings coating of mortars, concrete, artificial or natural stone or ceramics C04B41/45; laminated ceramic products B32B18/00; coating metallic materials C23; coating of glass C03C17/00, applying ceramic coatings on silicon for semi-conductor purposes H01L
• CPC Class Codes: C04B 41/52 : Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
• CPC Class Codes: C04B 41/89 : for obtaining at least two superposed coatings having different compositions
• CPC Class Codes: C08J 5/005 : Reinforced macromolecular compounds with nanosized materials, e.g. nanoparticles, nanofibres, nanotubes, nanowires, nanorods or nanolayered materials
• CPC Class Codes: C08K 2201/011 : Nanostructured additives
• CPC Class Codes: C08K 3/01 : characterized by their specific function
• CPC Class Codes: C08K 3/08 : Metals
• CPC Class Codes: H01C 7/112 : ZnO type
• CPC Class Codes: H01F 1/0063 : in a non-magnetic matrix, e.g. granular solids granular films H01F10/007
• CPC Class Codes: H01G 4/12 : Ceramic dielectrics H01G4/085 takes precedence
• CPC Class Codes: H01G 4/33 : Thin- or thick-film capacitors thin- or thick-film circuits H01L27/00; capacitors without a potential-jump or surface barrier specially adapted for integrated circuits, details thereof, multistep manufacturing processes therefor H01L28/40
• CPC Class Codes: H01M 4/9066 : of metal-ceramic composites or mixtures, e.g. cermets
• CPC Class Codes: H01M 8/1213 : characterised by the electrode/electrolyte combination or the supporting material
• CPC Class Codes: H01M 8/1246 : the electrolyte consisting of oxides
• CPC Class Codes: H01M 8/1253 : the electrolyte containing zirconium oxide
• CPC Class Codes: Y02E 60/50 : Fuel cells
• CPC Class Codes: Y02P 40/40 : Production or processing of lime, e.g. limestone regeneration of lime in pulp and sugar mills
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10S 977/89 : Deposition of materials, e.g. coating, cvd, or ald
• CPC Class Codes: Y10T 29/49002 : Electrical device making
• CPC Class Codes: Y10T 29/49082 : Resistor making
• CPC Class Codes: Y10T 428/26 : Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension

Abstract

Ion conducting solid electrolytes are constructed from nanoscale precursor material. Nanocrystalline powders are pressed into disc structures and sintered to the appropriate degree of densification. Metallic material is mixed with 0 to 65 vol % nanostructured electrolyte powders to form a cermet mix and then coated on each side of the disc and fitted with electrical leads. The electrical conductivity of a Ag/YSZ/Ag cell so assembled exhibited about an order of magnitude enhancement in oxygen ion conductivity. As an oxygen-sensing element in a standard O₂ /Ag/YSZ/Ag/N₂ set up, the nanocrystalline YSZ element exhibited commercially significant oxygen ion conductivity at low temperatures. The invention can be utilized to prepare nanostructured ion conducting solid electrolytes for a wide range of applications, including sensors, oxygen pumps, fuel cells, batteries, electrosynthesis reactors and catalytic membranes.

Claims

1. A nanostructured electrolytic structure, prepared by:

aggregating nanoscale particles of a ceramic electrolyte material to form an electrolytic structure; and

sintering said electrolytic structure at a temperature sufficient to cause its densification, said temperature being less than 1000°

C.

2. A nanostructured solid electrode, prepared by:

mixing a conductive material and nanoscale particles of an electrolyte material to form a nanocomposite structure;

sintering the nanocomposite structure at a selected temperature for a selected time, so as to form a porous structure having a 15-50 percent pore fraction; and

stabilizing said porous structure to produce a physically stable solid electrode.

3. An electrode/electrolyte structure, formed by depositing a nanostructured solid electrode according to claim 2 onto at least one surface of a solid electrolyte substrate.

4. The electrode/electrolyte structure of claim 3, where the solid electrolyte substrate and the nanoscale particles comprise yttria stabilized bismuth oxide.

5. The electrode/electrolyte structure of claim 3, wherein the electrolyte and the electrode have matched coefficients of thermal expansion.

6. A nanostructured electrolytic cell for electrochemical, electrocatalytic, or electrosynthesis applications, comprising:

an electrolyte layer having at least two sides, the layer produced by,

aggregating nanoscale particles of an electrolyte material to form an electrolyte precursor; and

sintering the electrolyte precursor at a temperature of less than 1000°

C. to densify it and form the electrolyte layer;

two electrodes, in contact with each of the two sides of the electrolyte layer respectively, each electrode comprising conductor material; and

two electrical leads, each in electrical contact with one of the two electrodes.

7. The electrolytic cell of claim 6, wherein the conductor material comprises silver.

8. A nanostructured solid electrolyte, prepared by:

evaporating an electrolyte precursor material in a gaseous atmosphere in a thermal reactor, thereby creating a vapor/gas mixture;

quenching said vapor/gas mixture by effecting its expansion through a selected pressure drop, the pressure drop sufficient to cause the formation of nanoscale particles of electrolyte material in a product gas;

separating the nanoscale particles of electrolyte material from the product gas;

pressing the nanoscale particles of electrolyte material to form an electrolytic structure having at least two sides; and

sintering said electrolytic structure at a temperature sufficient to densify it and produce the nanostructured solid electrolyte, said temperature being less than 1000°

C.

9. An electrolytic cell, comprising:

a nanostructured solid electrolyte according to claim 8;

a coating of a conductor material on each of at least two sides of the electrolyte to form an electrode on each of the at least two sides; and

an electrical lead in electrical contact with each of the electrodes.

10. A nanostructured solid electrolyte, comprising yttria stabilized zirconia and having an oxygen ion conductivity of at least 5×

10^-4 (Ω

-cm)^-1 at a temperature of less than or equal to 600°

C.

11. A nanostructured solid electrolyte, comprising yttria stabilized bismuth oxide and having an oxygen ion conductivity of at least 5×

10^-2 (Ω

-cm)^-1 at a temperature of less than or equal to 600°

C.

12. An electrolytic cell, comprising an electrolyte and an electrode, the electrolyte comprising yttria stabilized bismuth oxide and the electrode comprising yttria stabilized bismuth oxide and silver, wherein the cell has an impedance having a maximum imaginary component of less than or equal to 2 ohms at 475°

C. in air, and at least one of the electrolyte and electrode is nanostructured.

13. An electrolytic cell, comprising an electrolyte and an electrode, the electrolyte comprising yttria stabilized bismuth oxide and the electrode comprising yttria stabilized bismuth oxide and silver, wherein the electrode has a resistance no greater than 0.5 ohms at 625°

C., and the electrode is nanostructured.

14. A nanostructured sintered electrolyte, comprising a ceramic ion-conducting material having an average grain size of less than about 100 nm, wherein the ceramic ion-conducting material is free of tetravalent metal.

15. The nanostructured electrolyte of claim 14, wherein the ceramic ion-conducting material comprises an oxide of a trivalent metal.

16. The nanostructured electrolyte of claim 15, wherein the ceramic ion-conducting material is stabilized bismuth oxide.

17. The nanostructured electrolyte of claim 15, wherein the ceramic ion-conducting material is β

-alumina.

18. The nanostructured electrolyte of claim 14, wherein the ceramic ion-conducting material comprises an oxide of a divalent metal.

19. The nanostructured electrolyte of claim 14, wherein the ceramic ion-conducting material comprises an oxide of a monovalent metal.

20. A nanostructured sintered electrolyte, comprising a ceramic ion-conducting material having an average grain size of less than about 100 nm, wherein the ceramic ion-conducting material conducts an ion other than oxygen.

21. The nanostructured electrolyte of claim 20, wherein the ceramic ion-conducting material conducts a cation.

22. The nanostructured electrolyte of claim 21, wherein the cation is selected from the group consisting of sodium, silver, copper, and lithium.

23. The nanostructured electrolyte of claim 22, wherein the ceramic ion-conducting material is selected from the group consisting of AgI, RbAg₄ I₅, Rb₄ Cu₁₆ I₇ Cl₁₃, Li₃ N, β

-Al₂ O₃, NASICON systems, LISICON systems, and Li₂ S--SiS₂ --Li₃ PO₄ systems.

24. A nanocomposite electrode, produced by sintering particles of a conductor and nanoscale particles of another material, wherein the resistance of the nanocomposite electrode is less than or equal to about a fourth of the resistance of an electrode composed purely of the conductor.

25. The nanocomposite electrode of claim 24, wherein the conductor is silver and the electrolyte is yttria stabilized bismuth oxide.

26. The nanocomposite electrode of claim 24, wherein the nanocomposite electrode has a porosity in the range of 15-50 percent.