SOLID ELECTROLYTE, METHOD OF PREPARING THE SAME, PROTECTED CATHODE, ELECTROCHEMICAL BATTERY, AND ELECTROCHEMICAL DEVICE INCLUDING THE SAME

Provided are a solid electrolyte including a compound represented by Formula 1 or 3, the compound having a glass transition temperature of -30 °C or less, and a glass or glass-ceramic structure, a method of preparing the same, and an electrochemical device including the same. Formula 1 AQX-GaM(FCl)Z wherein, in Formula 1, Q is Li or a combination of Li and Na, K, or a combination thereof, M is a trivalent cation, or a combination thereof, X is a halogen other than F, pseudohalogen, OH, or a combination thereof, Z is a monovalent anion, or a combination thereof, 1