Solid ion conductor compound, solid electrolyte comprising the same, electrochemical cell comprising the same, and method of preparing the same

A solid ion conductor compound represented by Formula 1:

• LixM1aM2bClyBrz Formula 1
• wherein M1 comprises Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Sc, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Hg, or a combination thereof,
• M2 comprises La, Ce, Pr, Nd, Pm, Eu, Dy, Ho, Er, Tm, Yb, Lu, or a combination thereof,
• 0<x<3.5, 0≤a<1.5, 0<b<1.5, 0<y<6, 0<z<6, and 0.16<z/(y+z)<0.34,
• wherein the solid ion conductor compound has an ionic conductivity of 10−4 Siemens per centimeter or greater at −20° C. to 40° C., and
• wherein the solid ion conductor compound does not have a diffraction peak at 40°2θ to 44°2θ, when analyzed by X-ray diffraction using CuKα radiation,
• wherein the solid ion conductor compound comprises a phase having a crystal structure that belongs to a C2/m space group, and a phase having a crystal structure that belongs to a P3 m1 space group.