Solid Electrolyte Battery and Battery Module and Battery Pack Comprising Same

A solid electrolyte battery comprising a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode,

• wherein the negative electrode comprises:
• a negative electrode current collector;
• a first negative electrode active material layer formed on at least one surface of the negative electrode current collector and comprising a first negative electrode active material, a first solid electrolyte and a first electrolyte salt;
• and a second negative electrode active material layer formed on the first negative electrode active material layer and comprising a second negative electrode active material, a second solid electrolyte, a second electrolyte salt and a plasticizer having a melting point of 30-130° C.,
• the solid electrolyte battery is activated at a temperature between the melting point of the plasticizer and 130° C., and
• a solid electrolyte interface (SEI) layer is formed on the surface of the second negative electrode active material during an initial charge of the solid electrolyte battery.