Polymer formulation for coating a metal core, comprising the following components: a) a P(VDF-TrFE) copolymer solution at 10-30% by mass in a volatile solvent, b) a surfactant, said surfactant being based on an acrylic copolymer or based on high molecular weight block acrylic copolymers, and c) an adhesion promoter, said adhesion promoter comprising functional copolymers of hydroxyl type with acid groups or binders of ethoxysilane type, for example 3-aminopropyltriethoxysilane; the viscosity of the coating formulation, as measured at ambient temperature between 20°C and 25°C using a Brookfield viscometer according to Standard ASTM D2983, being between 1 and 500 Pa.s and preferably between 10 and 100 Pa.s, for a shear rate of 10 s -1; said volatile solvent being chosen from the following list: - ketones, notably methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone and acetone, - esters, notably ethyl acetate, methyl acetate, propyl acetate, butyl acetate and propylene glycol methyl ether acetate, - amides such as dimethylformamide and dimethylacetamide, - dimethyl sulfoxide, - furans, notably tetrahydrofuran, - carbonates, notably dimethyl carbonate, - phosphates, notably triethyl phosphate, - and mixtures thereof. a) a P(VDF-TrFE) copolymer solution at 10-30% by mass in a volatile solvent, b) a surfactant, said surfactant being based on an acrylic copolymer or based on high molecular weight block acrylic copolymers, and c) an adhesion promoter, said adhesion promoter comprising functional copolymers of hydroxyl type with acid groups or binders of ethoxysilane type, for example 3-aminopropyltriethoxysilane; the viscosity of the coating formulation, as measured at ambient temperature between 20°C and 25°C using a Brookfield viscometer according to Standard ASTM D2983, being between 1 and 500 Pa.s and preferably between 10 and 100 Pa.s, for a shear rate of 10 s -1; said volatile solvent being chosen from the following list: - ketones, notably methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone and acetone, - esters, notably ethyl acetate, methyl acetate, propyl acetate, butyl acetate and propylene glycol methyl ether acetate, - amides such as dimethylformamide and dimethylacetamide, - dimethyl sulfoxide, - furans, notably tetrahydrofuran, - carbonates, notably dimethyl carbonate, - phosphates, notably triethyl phosphate, - and mixtures thereof. the viscosity of the coating formulation, as measured at ambient temperature between 20°C and 25°C using a Brookfield viscometer according to Standard ASTM D2983, being between 1 and 500 Pa.s and preferably between 10 and 100 Pa.s, for a shear rate of 10 s -1; said volatile solvent being chosen from the following list: - ketones, notably methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone and acetone, - esters, notably ethyl acetate, methyl acetate, propyl acetate, butyl acetate and propylene glycol methyl ether acetate, - amides such as dimethylformamide and dimethylacetamide, - dimethyl sulfoxide, - furans, notably tetrahydrofuran, - carbonates, notably dimethyl carbonate, - phosphates, notably triethyl phosphate, - and mixtures thereof. - ketones, notably methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone and acetone, - esters, notably ethyl acetate, methyl acetate, propyl acetate, butyl acetate and propylene glycol methyl ether acetate, - amides such as dimethylformamide and dimethylacetamide, - dimethyl sulfoxide, - furans, notably tetrahydrofuran, - carbonates, notably dimethyl carbonate, - phosphates, notably triethyl phosphate, - and mixtures thereof.