SECONDARY BATTERY

A secondary battery includes a body including a solid electrolyte layer, and a positive electrode and a negative electrode disposed with the solid electrolyte layer interposed therebetween; and first and second external electrodes respectively disposed on one surface and the other surface of the body, opposite to the one surface, and respectively connected to the positive electrode and the negative electrode, wherein the positive electrode comprises a positive electrode active material layer and a first electrolytic mixing portion disposed at an interface of the positive electrode in contact with the solid electrolyte layer. The first electrolytic mixing portion is a mixture of a positive electrode active material and a liquid phase and/or gel phase electrolyte.