Solid electrolyte material and battery

1. A solid electrolyte material comprising:

a first crystal phase,

wherein the first crystal phase has a composition that is deficient in Li as compared with a composition represented by the following composition formula (1):

Li 3 Y 1 Cl 6 ,

wherein the first crystal phase is represented by the following composition formula (2):

Li 3-3δ Y 1+δ Cl 6 , where

0<δ≤0.15.

2. The solid electrolyte material according to claim 1 , wherein 0.01≤δ≤0.133.

3. The solid electrolyte material according to claim 1 , wherein

the solid electrolyte material has an X-ray diffraction pattern that includes a peak in each of a first range, a second range, and a third range, the X-ray diffraction pattern being measured using Cu-Kα radiation as an X-ray source,

in the first range, a diffraction angle 2θ is 30.34 degrees or more and 32.36 degrees or less,

in the second range, the diffraction angle 2θ is 39.51 degrees or more and 42.07 degrees or less, and,

in the third range, the diffraction angle 2θ is 47.18 degrees or more and 50.30 degrees or less.

4. The solid electrolyte material according to claim 3 , wherein

the X-ray diffraction pattern further includes a peak in a fourth range in which the diffraction angle 2θ is 15.2 degrees or more and 16.23 degrees or less and in a fifth range in which the diffraction angle 2θ is 52.4 degrees or more and 54.6 degrees or less.

5. The solid electrolyte material according to claim 3 , wherein

the X-ray diffraction pattern satisfies FWHM/2θ p ≤0.01, where FWHM denotes a full width at half maximum of the peak in the first range, and 2θ p denotes a central value of the peak.

6. The solid electrolyte material according to claim 1 , wherein

the first crystal phase contains a chlorine sublattice, and

the chlorine sublattice has an arrangement of chlorine that includes an atomic arrangement of a distorted hexagonal close-packed structure.

7. The solid electrolyte material according to claim 1 , wherein

the first crystal phase contains an atomic arrangement of a Li 3 YbCl 6 structure.

8. The solid electrolyte material according to claim 1 , wherein

the solid electrolyte material has an X-ray diffraction pattern that includes a peak in at least one range selected from the group consisting of a range in which a diffraction angle 2θ is 29.18 degrees or more and 31.03 degrees or less and a range in which the diffraction angle 2θ is 33.83 degrees or more and 36.00 degrees or less, the X-ray diffraction pattern being measured using Cu-Kα radiation as an X-ray source.

9. The solid electrolyte material according to claim 8 , further comprising

a second crystal phase,

wherein the second crystal phase has a LiCl parent structure.

10. The solid electrolyte material according to claim 1 , wherein

the solid electrolyte material has an X-ray diffraction pattern that includes a peak in at least one range selected from the group consisting of a range in which a diffraction angle 2θ is 14.34 degrees or more and 15.23 degrees or less and a range in which the diffraction angle 2θ is 25.65 degrees or more and 27.26 degrees or less, the X-ray diffraction pattern being measured using Cu-Kα radiation as an X-ray source.

11. The solid electrolyte material according to claim 10 , further comprising

a third crystal phase,

wherein the third crystal phase has a YCl 3 parent structure.

12. A battery comprising:

the solid electrolyte material according to claim 1 ;

a positive electrode;

a negative electrode; and

an electrolyte layer between the positive electrode and the negative electrode,

wherein at least one selected from the group consisting of the positive electrode, the negative electrode, and the electrolyte layer contains the solid electrolyte material.