The synthesis of a perfluorinated compound of average composition C70F56 is described. The associated properties are examined at the molecular level and for the bulk material. It is shown that fluorination involves an expansion of the carbon frame and that the length of the resulting C-F bond is elongated to 1.45 Å and possesses an ionocovalent nature. The corresponding crystalline product has fcc symmetry related to complete orientational disorder of the fluorinated molecules. When C70F56 is used in lithium batteries, the formation of LiF results via a preliminary intercalation reaction.