SEPARATOR AND PREPARATION METHOD THEREOF

A separator and a preparation method thereof are provided. The separator includes: a first isolation layer, configured to contact with a positive electrode sheet of the lithium battery; a third isolation layer, configured to contact with a negative electrode sheet of the lithium battery; and a second isolation layer, provided between the first isolation layer and the third isolation layer; where the first isolation layer includes a ceramic material, the second isolation layer includes a polymer layer material, and the third isolation layer includes a modified polymer composite layer material.