Methods for reductively polymerizing vinylic based monomers from a solution thereof onto the surface of an electrode material, resulting in thin, electrically insulating solid-polymer electrolyte coatings strongly bound to the surface of the electrode material, are described. The strong bond permits a second electrode to be coated directly onto the solid-polymer electrolyte, thereby incorporating the required components for a Li-ion battery cell. At least one initiator species, which is readily reduced by accepting an electron from the electrode material, is included in electropolymerization deposition solution for permitting the polymerization of vinylic species that would otherwise not electrochemically polymerize without damage to either the electrode material or to the solvents employed.