Solid electrolyte material and battery using same

A solid-electrolyte material comprising:

• Li, Y, O, and X,
• wherein X is at least two elements selected from the group consisting of F, Cl, Br, and I;
• wherein O is present in a surface region of the solid-electrolyte material;
• and
• wherein a peak is present at a diffraction angle 2θ of greater than or equal to 13.6° and less than or equal to 14.6°, a diffraction angle 2θ of greater than or equal to 27.8° and less than or equal to 29.0°, a diffraction angle 2θ of greater than or equal to 32.0° and less than or equal to 33.3°, a diffraction angle 2θ of greater than or equal to 46.3° and less than or equal to 47.8°, and a diffraction angle 2θ of greater than or equal to 57.2° and less than or equal to 59.8° in an X-ray diffraction pattern obtained by an X-ray diffraction measurement using Cu-Kα radiation.