High performance energy storage devices

A lead-acid battery comprising:- at least one lead-based negative electrode;- at least one lead dioxide-based positive electrode;- at least one capacitor electrode; and- electrolyte in contact with the electrodes;wherein a battery part is formed by thelead based negative electrode and the lead dioxide-based positive electrode;and 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;and wherein all negative electrodes are connected to a negative busbar, and all positive electrodes are connected to a positive busbar. The capacitor electrode may be a capacitor negative electrode comprising carbon and an additive mixture selected from oxides, hydroxides or sulfates of lead, zinc, cadmium, silver and bismuth, or a capacitor negative electrode comprising carbon, red lead, antimony in oxide, hydroxide orsulfateform, and optionally other additives. The capacitor electrode may be used in asymmetric capacitors and batteries of other types.