Set forth herein are garnet material compositions, e.g., lithium-stuffed garnets and lithium-stuffed garnets doped with alumina, which are suitable for use as electrolytes and catholytes in solid state battery applications. Also set forth herein are lithium-stuffed garnet thin films having fine grains therein. Disclosed herein are novel and inventive methods of making and using lithium-stuffed garnets as catholytes, electrolytes and/or anolytes for all solid state lithium rechargeable batteries. Also disclosed herein are novel electrochemical devices which incorporate these garnet catholytes, electrolytes and/or anolytes. Also set forth herein are methods for preparing novel structures, including dense thin (<50 um) free standing membranes of an ionically conducting material for use as a catholyte, electrolyte, and, or, anolyte, in an electrochemical device, a battery component (positive or negative electrode materials), or a complete solid state electrochemical energy storage device. Also, the methods set forth herein disclose novel sintering techniques, e.g., for heating and/or field assisted (FAST) sintering, for solid state energy storage devices and the components thereof.

Disclosed herein are compositions containing zirconium and cerium having a surprisingly small particle size. The compositions disclosed herein contain zirconium, cerium, optionally yttrium, and optionally one or more other rare earth oxides other than cerium and yttrium. The compositions exhibit a particle size characterized by a D.sub.90 value of about 5 μm to about 30 μm and a D.sub.99 value of about 5 um to about 40 um. Further disclosed are processes of producing these compositions using oxalic acid and supercritical drying in the process. The compositions can be used as a catalyst and/or part of a catalytic system. The composition is prepared by co-precipitation using oxalic acid and supercritical drying.

A cerium-zirconium based mixed oxide composition have: (a) a Ce:Zr molar ratio of 1 or less, and (b) a cerium oxide content of 10-50% by weight. The composition has (i) a surface area of at least 18 m.sup.2/g, and a total pore volume as measured by N.sub.2 physisorption of at least 0.11 cm.sup.3/g, after ageing at 1100° C. in an air atmosphere for 6 hours, (ii) a surface area of at least 42 m.sup.2/g, and a total pore volume as measured by N.sub.2 physisorption of at least 0.31 cm.sup.3/g, after ageing at 1000° C. in an air atmosphere for 4 hours, and (iii) Dynamic Oxygen Storage Capacity (D-OSC) value as measured by H.sub.2-TIR of greater than 500 μmol/g at 600° C. after aging at 800° C. in an air atmosphere for 2 hours. A process contacts the exhaust gas with the composition Another process is for preparing the composition.

Disclosed herein are materials and processes for production of lithium oxide materials, such as lithium lanthanum zirconium oxide (LLZO), having a small particle size and high density for use in lithium-ion batteries. Some embodiments are directed to forming and then heating a multiphase material comprising lithium carbonate and La.sub.2Zr.sub.2O.sub.7 in the presence of hydrogen gas at a temperature below the melting point of the lithium carbonate, such that at least a portion of the lithium carbonate decomposes to form lithium oxide. In some embodiments, the lithium oxide is heated to a temperature sufficient to crystallize the lithium oxide to form the solid electrolyte material comprising lithium lanthanum zirconium oxide (LLZO) particles.

A cerium-zirconium oxide-based ionic conductor (CZOIC) material including zirconium oxide in an amount ranging from 5 wt. % up to 95 wt. %, cerium oxide in an amount ranging from 95 wt. % to 5 wt. %, and at least one oxide or a rare earth metal in an amount ranging from 30 wt. % or less, based on the overall mass of the CZOIC material. The CZOIC material exhibits a structure comprising one or more expanded unit cells and a plurality of crystallites having ordered nano-domains. The structure of the CZOIC material exhibits a crystal lattice defined by a d-value measured at multiple (hkl) locations using a SAED technique that exhibit distortions, such that the d-values for the same (hkl) location varies from about 2% to about 5% from the d-value measured for a reference cerium-zirconium material at the same (hkl) location.

A ceramic powder material containing: a first garnet-type compound containing Li, La, and Zr; and a second garnet-type compound containing Li, La, and Zr and having a composition different from a composition of the first garnet-type compound, in which the first garnet-type compound and the second garnet-type compound are represented by Formula [1] Li.sub.7-(3x+y)M1.sub.xLa.sub.3Zr.sub.2-yM2.sub.yO.sub.12, where Ml is Al or Ga, M2 is Nb or Ta, the first garnet-type compound satisfies 0≤(3x+y)≤0.5, and the second garnet-type compound satisfies 0.5<(3x+y)≤1.5.

Provided are a composite oxide powder from which dense solid electrolyte objects having a high ion conductivity can be produced and a method for producing the composite oxide powder. The composite oxide powder is composed of particles comprising lithium (Li), lanthanum (La), zirconium (Zr), and oxygen (O) and having a cubic garnet-type crystal structure, and has a volume particle size distribution in which the 50% diameter (D50) is 1,000 nm or smaller, the composite oxide powder having a pyrochlore phase content of 10 mass % or less.

Disclosed herein are embodiments of doped and undoped spherical or spheroidal lithium lanthanum zirconium oxide (LLZO) powder products, and methods of production using microwave plasma processing, which can be incorporated into solid state lithium ion batteries. Advantageously, embodiments of the disclosed LLZO powder display a high quality, high purity stoichiometry, small particle size, narrow size distribution, spherical morphology, and customizable crystalline structure.

Materials for electrochemical cells are provided. BaZr.sub.0.4Ce.sub.0.4M.sub.0.2O.sub.3 compounds, where M represents one or more rare earth elements, are provided for use as electrolytes. PrBa.sub.0.5Sr.sub.0.5Co.sub.2−xFe.sub.xO.sub.5+δ is provided for use as a cathode. Also provided are electrochemical cells, such as protonic ceramic fuel cells, incorporating the compounds as electrolytes and cathodes.

Disclosed herein are compositions comprising zirconium and cerium having a surprisingly small particle sizes. The compositions disclosed herein contain zirconium, cerium, optionally yttrium, and optionally one or more rare earths other than cerium and yttrium The compositions exhibit a particle size characterized by a Dso value of about 20 μm to about 45 μm and a D.sub.99 value of about 55 μm to about 1 00 μm. Further disclosed are processes of producing these compositions using oxalic acid in the process. The compositions can be used as a catalyst and/or part of a catalytic system for automobile exhaust gas.