Electrode for storing electrical energy including a metal current collector and an active material, the current collector being coated on at least one portion of one of its faces with at least one protective layer placed between the current collector and the active material, the protective layer including: (A) a polymer matrix including: (A1) at least one cross-linked epoxy polymer or copolymer, (A2) at least one elastomer, and (B) conductive fillers. This system is used in aqueous electrolyte supercapacitors, the protective layer allowing a very significant reduction in corrosion problems that are generally associated with the use of aqueous electrolytes to be achieved and the adhesion of the active material to the metal collector to be improved.