Abstract: A cathode active material includes a lithium composite metal oxide and a solid electrolyte layer which surrounds the lithium composite metal oxide, and the solid electrolyte layer includes a sulfide-based solid electrolyte doped with oxygen.

Abstract: Disclosed is a composite obtained by combining a chloride-based solid electrolyte having excellent stability under high-voltage conditions with a carbon-based conductive material into a composite. Further, a positive electrode material including the composite, a positive electrode including the same, and an all-solid-state battery including the same are disclosed. The composite has excellent balance between ionic conductivity and electronic conductivity and has excellent stability in a voltage range in which the battery operates, and thus is applied as a coating layer on a surface of the positive electrode active material to improve performance.