NOVELTY - Lead-acid battery comprises lead-based negative electrode(s); lead dioxide-based positive electrode(s); capacitor electrode(s); and electrolyte in contact with the electrodes. A battery part is formed by the cathode and the anode. An asymmetric capacitor part is formed by the capacitor electrode and one electrode selected from the lead based cathode and the lead-dioxide based anode.    USE - For use as mild hybrid electric vehicle battery.    ADVANTAGE - The battery has improved life span and/or improved overall performance compared to current batteries.    DETAILED DESCRIPTION - Lead-acid battery comprises lead-based cathode(s) (1); lead dioxide-based anode(s) (2); capacitor electrode(s) (3); and electrolyte (7) in contact with the electrodes. A battery part is formed by the lead based negative electrode and the lead dioxide-based positive electrode. An asymmetric capacitor part is formed by the capacitor electrode and one electrode selected from the lead based negative electrode and the lead-dioxide based positive electrode. All negative electrodes are connected to a negative busbar (9), and all positive electrodes are connected to a positive busbar (8). INDEPENDENT CLAIMS are also included for:    (a) capacitor cathode comprising a current collector and a paste coating comprised of a high surface area capacitor material, a binder and 5-40 weight % additive or additive mixture selected from hydroxides or sulfates of lead, zinc, cadmium, silver and bismuth, provided that the additive includes at least one oxide, hydroxide or sulfate of lead or zinc; and    (b) a capacitor anode comprising a current collector and a paste coating, the paste coating comprising a high surface area capacitor material, a binder and 10-40 weight % additive mixture comprised of lead oxide, an oxide, hydroxide or sulfate of antimony, and optionally oxides, hydroxides or sulfates of iron and lead.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic side view of a lead-acid battery.    Cathode (1)    Anode (2)    Capacitor electrode (3)    Separators (6)    Electrolyte (7)    Positive busbar (8)    Negative busbar (9)