Solid-state lithium ion electrolytes of lithium silicate based composites are provided which contain an anionic framework capable of conducting lithium ions. An activation energy for lithium ion migration in the solid state lithium ion electrolytes is 0.5 eV or less and room temperature conductivities are greater than 10.sup.0.5 S/cm. Composites of specific formulae are provided and methods to alter the composite materials with inclusion of aliovalent ions shown. Lithium batteries containing the composite lithium ion electrolytes are also provided.

A solid oxide fuel cell includes a support of which a main component is a metal, a mixed layer that is provided on the support and includes a metallic material and a ceramics material, an intermediate layer that is provided on the mixed layer and includes an electron conductive ceramics material, and an anode that is provided on the intermediate layer and includes an oxygen ion conductive ceramics material and Ni. A ratio of a metal component in the intermediate layer is smaller than a ratio of the metallic material in the mixed layer.

Methods for forming a metal oxide electrolyte improve ionic conductivity. Some of those methods involve applying a first metal compound to a substrate, converting that metal compound to a metal oxide, applying a different metal compound to the metal oxide, and converting the different metal compound to form a second metal oxide. That substrate may be in nanobar form that conforms to an orientation imparted by a magnetic field or an electric field applied before or during the converting. Electrolytes so formed can be used in solid oxide fuel cells, electrolyzers, and sensors, among other applications.

The present invention relates to rhomboidal phase bismuth oxide that maintains electric conductivity of at least about 1×10.sup.−2 S/cm at temperature of about 500° C. for at least about 100 hours. In particular, the bismuth oxides of the invention have stable conductivity at a temperature range from about 500° C. to about 550° C.

A membrane electrode assembly of an electrochemical device includes a proton conductive solid electrolyte membrane and an electrode including Ni and an electrolyte material which contains as a primary component, at least one of a first compound having a composition represented by BaZr.sub.1-x1M.sup.1.sub.x1O.sub.3 (M.sup.1 represents at least one element selected from trivalent elements each having an ion radius of more than 0.720 A° to less than 0.880 A°, and 0<x.sub.1<1 holds) and a second compound having a composition represented by BaZr.sub.1-x2Tm.sub.x2O.sub.3 (0<x.sub.2<0.3 holds).

The present invention relates to rhomboidal phase bismuth oxide that maintains electric conductivity of at least about 1×10.sup.−2 S/cm at temperature of about 500° C. for at least about 100 hours. In particular, the bismuth oxides of the invention have stable conductivity at a temperature range from about 500° C. to about 550° C.

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.

Set forth herein are processes for making lithium-stuffed garnet oxides (e.g., Li.sub.7La.sub.3Zr.sub.2O.sub.12, also known as LLZO) that have passivated surfaces comprising a fluorinate and/or an oxyfluorinate species. These surfaces resist the formation of oxides, carbonates, hydroxides, peroxides, and organics that spontaneously form on LLZO surfaces under ambient conditions. Also set forth herein are new materials made by these processes.

An oxide ion conductor has a X.sub.3Z.sub.2(TO.sub.4).sub.3 structure, where X is a divalent metal element, Z is a trivalent metal element, and T is a tetravalent metal element, and has a composition expressed by (X.sub.1-xA.sub.x).sub.3(Z.sub.1-yB.sub.y).sub.2(T.sub.1-zC.sub.z).sub.3O.sub.12+δ where the element X is Ca, Fe, Gd, Ba, Sr, Mn, and/or Mg, the element Z is Al, Cr, Fe, Mn, V, Ga, Co, Ni, Ru, Rh, and/or Ir, the element T is Si and/or Ge, an element A is La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and/or Sr, an element B is Zn, Mn, Co, Ru, and/or Rh, and an element C is Si, Al, Ga, and/or Sn, 0≤x≤0.2, 0≤y≤0.2, and 0≤z≤0.2 are satisfied, and δ is a value securing electrical neutrality.

Performance of a thermal lithium battery is improved by improving the ion-transport characteristics of a solid lithium iodide electrolyte. The lithium iodide lattice of the solid electrolyte includes defects that improve the ion-transport characteristics of the solid lithium iodide electrolyte. In one example, the defects are due to the introduction of nanoparticles that result in grain boundary defects. The defects resulting at the grain boundaries with the nanoparticles improve the ion transport characteristics of the electrolyte. In another example, defects originating from the synthesis process are pinned by the presence of nanoparticles and/or the reinforcing structure. In another example, the defects are aliovalent substitution defects. A cation that is aliovalent to the lithium cation (Li.sup.+), such as a barium cation (Ba.sup.2+), creates an aliovalent substitution defect in the lithium iodide lattice. In order to maintain charge neutrality in the lattice, two lithium cations are replaced by a single barium cation creating the defect in the lattice.