An electrode assembly (210, 201) for a rechargeable battery, comprising a plurality of unit cells stacked in a thickness direction; a first functional unit cell disposed at an outermost first surface of the plurality of unit cells; and a second functional unit cell at an outermost second surface of the plurality of unit cells that is opposed to the first surface, wherein each of the first functional unit cell and the second functional unit cell comprises: a negative electrode, a positive electrode and a separator disposed between the negative electrode and the positive electrode, the positive electrode comprises a positive current collector, a positive active material layer disposed on at least one surface of the positive current collector and comprising a positive active material having a lower third reference potential than the first reference potential, wherein the positive active material is a composite oxide of a metal selected from cobalt, manganese, nickel, and a combination thereof, and lithium, and a first functional layer disposed on the positive active material layer and comprising a first active material having a second reference potential lower than the first reference potential, wherein the first active material is selected from the group consisting of Li a Fe 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li a Mn 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li a Co 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); and Li 4-x M x Ti y O 12-z (0 ≤ x ≤ 3, 1 ≤ y ≤ 5, - 0.3 ≤ z ≤ 0.3), with G being selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and a combination thereof; and M being selected from Mg, La, Tb, Gd, Ce, Pr, Nd, Sm, Ba, Sr, Ca, or a combination thereof, wherein the reference potentials are reduction average potentials based on a lithium metal (Li/Li+). a plurality of unit cells stacked in a thickness direction; a first functional unit cell disposed at an outermost first surface of the plurality of unit cells; and a second functional unit cell at an outermost second surface of the plurality of unit cells that is opposed to the first surface, wherein each of the first functional unit cell and the second functional unit cell comprises: a negative electrode, a positive electrode and a separator disposed between the negative electrode and the positive electrode, the positive electrode comprises a positive current collector, a positive active material layer disposed on at least one surface of the positive current collector and comprising a positive active material having a lower third reference potential than the first reference potential, wherein the positive active material is a composite oxide of a metal selected from cobalt, manganese, nickel, and a combination thereof, and lithium, and a first functional layer disposed on the positive active material layer and comprising a first active material having a second reference potential lower than the first reference potential, wherein the first active material is selected from the group consisting of Li a Fe 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li a Mn 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li a Co 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); and Li 4-x M x Ti y O 12-z (0 ≤ x ≤ 3, 1 ≤ y ≤ 5, - 0.3 ≤ z ≤ 0.3), with G being selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and a combination thereof; and M being selected from Mg, La, Tb, Gd, Ce, Pr, Nd, Sm, Ba, Sr, Ca, or a combination thereof, wherein the reference potentials are reduction average potentials based on a lithium metal (Li/Li+). a negative electrode, a positive electrode and a separator disposed between the negative electrode and the positive electrode, the positive electrode comprises a positive current collector, a positive active material layer disposed on at least one surface of the positive current collector and comprising a positive active material having a lower third reference potential than the first reference potential, wherein the positive active material is a composite oxide of a metal selected from cobalt, manganese, nickel, and a combination thereof, and lithium, and a first functional layer disposed on the positive active material layer and comprising a first active material having a second reference potential lower than the first reference potential, wherein the first active material is selected from the group consisting of Li a Fe 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li a Mn 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); Li a Co 1-g G g PO 4 (0.90 ≤ a ≤ 1.8, 0 ≤ g ≤ 0.5); and Li 4-x M x Ti y O 12-z (0 ≤ x ≤ 3, 1 ≤ y ≤ 5, - 0.3 ≤ z ≤ 0.3), with G being selected from Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and a combination thereof; and M being selected from Mg, La, Tb, Gd, Ce, Pr, Nd, Sm, Ba, Sr, Ca, or a combination thereof, wherein the reference potentials are reduction average potentials based on a lithium metal (Li/Li+).