Lithium battery insulating film and preparation method thereof

The invention provides a lithium battery insulating film and a preparation method thereof, the lithium battery insulating film comprises: a polyester film, the polyester film comprises uniformly distributed nanometer titanium dioxide and a heat conduction material, and part of the nanometer titanium dioxide coats the surface of the heat conduction material. The preparation method comprises the following steps: preparing a nano titanium dioxide dispersion liquid; mixing a polyester material and a heat-conducting material, melting the polyester material, and adding the nano titanium dioxide dispersion liquid into the heat-conducting material and the molten polyester material; and performing cold casting to form a film, so that the nano titanium dioxide and the heat-conducting material in the nano titanium dioxide dispersion liquid are dispersed in the polyester material, and part of the nano titanium dioxide is coated on the surface of the heat-conducting material. The lithium battery insulating film provided b