▎ 摘　　要

NOVELTY - Functionalized flexible film comprises 1-10 pts. wt. graphene oxide, 5-15 pts. wt. binder and 10-80 pts. wt. phosphorus flame retardant. The graphene oxide is graphene oxide containing large amount of hydrophilic group, such as graphene oxide containing large amount of oxygen-containing functional group. The graphene oxide is sheet graphene oxide. USE - Functionalized flexible film used as a separator in a battery containing a high nickel cathode material. The battery may be a lithium metal power battery, preferably a lithium metal battery, more preferably a lithium metal battery containing a high nickel anode material (all claimed). ADVANTAGE - The functionalized flexible film has enhanced heat conducting performance, wetting property and mechanical strength, improved membrane wetting property, heat distribution behavior and deformation performance, and excellent cycle stability. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for following: (1) a method for preparing a functionalized flexible film, which involves spreding slurry including the components flat on a substrate, and washing with a film-forming solvent to form a film, drying after the film is formed, and separating film layer and the substrate to obtain functionalized flexible film; and (2) a battery, which comprises functionalized flexible film produced by the preparation method.