Garnet-type ion-conducting oxide and method for producing oxide electrolyte sintered body
A garnet-type ion-conducting oxide configured to inhibit lithium carbonate formation on the surface of crystal particles thereof, and a method for producing an oxide electrolyte sintered body using the garnet-type ion-conducting oxide. The garnet-type ion-conducting oxide represented by a general formula (Li x-3y-z , E y , H z )L α M β O γ (where E is at least one kind of element selected from the group consisting of Al, Ga, Fe and Si; L is at least one kind of element selected from an alkaline-earth metal and a lanthanoid element: M is at least one kind of element selected from a transition element which be six-coordinated with oxygen and typical elements in groups 12 to 15 of the periodic table; 3≤x−3y−z≤; 0≤y≤0.22; C≤z≤2.8; 2.5≤α≤3.5; 1.5≤≈≤2.5; and 11≤γ≤13), wherein a half-width of a diffraction peak which has a highest intensity and which is observed at a diffraction angle (2θ) in a range of from 29° to 32° as a result of X-ray diffraction measurement using CuKα radiation, is 0.164° or less.
1. A method for producing an oxide electrolyte sintered body, the method comprising:
subjecting crystal particles of a garnet-type ion-conducting oxide to a hydrogen ion partial substitution step in which lithium ions are substituted with hydrogen to obtain crystal particles of a garnet-type ion-conducting oxide represented by the following formula (1):
(Li x-3y-z E y H z )L α M β O γ (1),
wherein, in formula (1), E is at least one element selected from the group consisting of Al, Ga, Fe and Si; L is La; M is at least one element selected from the group consisting of Zr, Nb and Ta; 3≤x−3y−z≤7; 0≤y<0.22; 0<z≤2.8; 2.5≤α≤3.5; 1.5≤β≤2.5; and 11≤γ≤13,
wherein a half-width of a diffraction peak which has a highest intensity and which is observed at a diffraction angle (2θ) in a range of from 29° to 32° as a result of X-ray diffraction measurement using CuKα radiation is from 0.092° to 0.164°,
preparing a lithium-containing flux, and
sintering a mixture of the flux and the crystal particles of the garnet-type ion-conducting oxide represented by the formula (1), by heating at a temperature equal to or more than a melting point of the flux.