Method for preparing expanded foamed graphite film

A method for preparing an expanded foamed graphite film, comprising the following steps:

• Step A:
• impregnating a synthetic graphite film into an intercalator for an interlayer intercalation treatment to prepare an intercalated graphite film;
• and
• Step B:
• performing a thickness-limited expansion and foaming to the intercalated graphite film obtained in the Step A, with an expansion ratio y of 2-25, to obtain an expanded foamed intercalated graphite film, wherein y=T2/T1, T1 refers to a first thickness of the intercalated graphite film obtained in the Step A, and T2 refers to a second thickness of the expanded foamed intercalated graphite film after the thickness-limited expansion and foaming;
• wherein in the Step A, the intercalator comprises conductive particles, and the conductive particles account for 0.01-5% of a total mass of the intercalator;
• wherein the conductive particles comprise one or more selected from the group consisting of boron nitride, boron carbide, silicon carbide, aluminum nitride, and silicon nitride.