ION-CONDUCTIVE SOLID ELECTROLYTE COMPOUND, METHOD FOR PREPARING SAME, AND ELECTROCHEMICAL DEVICE COMPRISING SAME

Provided is an ion-conductive solid electrolyte compound, as a crystalline oxide, including a stoichiometric formula of “A(MTO)”. In the stoichiometric formula, A is a cation having an oxidation state of +1, M is a cation having an oxidation state of +4, +5, or +6, T is a cation having an oxidation state of +4, +5, or +6, and x and y are each independently a real number greater than 0, wherein x is equal to or less than 3y. The ion-conductive solid electrolyte compound has a high ionic conductivity and a low electronic conductivity.