Solid electrolyte with high ionic conductivity, method for preparing the same, and battery using the same

A solid electrolyte including a composition represented by Formula 1 below is provided:aLiO-bBO-cM-dX (1) wherein M is at least one selected from the group consisting of TiO, VO, WO, and TaO; X is at least one selected from LiCl and LiSO; 0.4