SOLID ELECTROLYTE AND ALL-SOLID-STATE BATTERY INCLUDING THE SAME

The present invention relates to a solid electrolyte that includes sulfide-based solid electrolyte particles; and a buffer layer including LiCOthat is formed on the sulfide-based solid electrolyte particle, wherein, in a near-infrared (NIR) spectrum, an integral value of a LiCOband present in a range of 5,200 cmto 4,725 cmis in a range of 2.0 to 8.0, and an all-solid-state battery including the same.