NOVELTY - The separator (4) comprises a porous base material layer (11), and a polymer coating layer (12, 13) formed on a surface of the base material layer. The polymer coating layer comprises a first fluorinated copolymer, a non-fluorinated polymer, and a second fluorinated polymer that is different from the first fluorinated copolymer, where a weight ratio of the first fluorinated copolymer to the non-fluorinated polymer is 2:1-1:2. A weight average molecular amount of the first fluorinated copolymer is 10000-600000.    USE - The separator is useful in a lithium battery (claimed) such as a pouch-shape lithium battery, which is useful in electric vehicles, a notebook computer and a smartphone.    ADVANTAGE - The separator improves discharging capacity, energy density, cyclic characteristics and stability of the lithium battery, and has high oxidation resistance and increased adhesive force with respect to an electrode.    DETAILED DESCRIPTION - The separator (4) comprises a porous base material layer (11), and a polymer coating layer (12, 13) formed on a surface of the base material layer. The polymer coating layer comprises a first fluorinated copolymer, a non-fluorinated polymer, and a second fluorinated polymer that is different from the first fluorinated copolymer, where a weight ratio of the first fluorinated copolymer to the non-fluorinated polymer is 2:1-1:2. A weight average molecular amount of the first fluorinated copolymer is 10000-600000. The non-fluorinated polymer has a higher surface energy than the first fluorinated polymer or has a surface energy of greater than or equal to 3 5 mN/m at a temperature of 20 degrees C. The polymer coating layer is formed as a gel. A thickness of the porous base material layer is 1-100 mu m. INDEPENDENT CLAIMS are included for:    (1) a lithium battery; and    (2) a method of preparing a separator.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a separator.    Separator (4)    Porous base material layer (11)    Polymer coating layer. (12, 13)