Abstract: The present invention relates to an electrode comprising a current collector formed by a metal strip which is coated on at least one of the faces thereof with a composition of electrochemically active materials, the composition comprising at least one lithium manganese iron phosphate having the following formula: LixMn1-y-zFeyMzPO4, where M is selected from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo, alone or in a mixture, with 0.8?x?1.2; 0.5?1-y-z<1; 0.05?y?0.5 and 0?z?0.2; the current collector having undergone chemical pickling of at least one of the faces thereof.