Metallization by deposit under vacuum of metal on a face of a support film of synthetic resin at a thickness of 0.005 to 0.1 micron, followed by the electrochemical deposit of an additional metallic layer, whose thickness is between 0.1 and 4 microns. A coating of an electrode of a generator is then applied on the surface of the collector thus prepared. The assembly is characterized by the adhesion of its components and its facility of mechanized handling during the steps of assembling the complete generator.