NOVELTY - The system has a bipolar electrode (1) that is common to an electrochemical accumulator (10) and a supercapacitor (20). The electrode has an electrically conducting support (2) supporting an electrode (3) of the accumulator and an electrode (4) of the supercapacitor, where the conducting support is made of aluminum. Electrical connections (C1-C3) are provided to the accumulator and the supercapacitor. The bipolar electrode provides the electrical connection (C2) that is common to the accumulator and the supercapacitor.    USE - Hybrid bipolar system for storing electric energy for starting an engine of a hybrid vehicle.    ADVANTAGE - The system provides the common electrical connection between the supercapacitor and the accumulator in an easy manner by the bipolar electrode. The system manages connection/disconnection actions between the supercapacitor and the accumulator, so as to permit the supercapacitor to remain operational, when the accumulator is not worked. The system assures better load collection and decreased internal resistance, and is robust. The system ensures better heat dissipation, and provides wide range of usage temperature. The system permits an integration of same materials of electrodes associated to same electrolytes with different preparations for the electrodes of the accumulator and the electrodes of the supercapacitor. The system is simple and inexpensive, and provides high energy density and strong power density. The supercapacitor and the accumulator are integrated into a single element, so that the system is compact.    DETAILED DESCRIPTION - The accumulator has an electrochemical cell comprising an electro-active anode made of lithium titanium oxide or graphite, and an electro-active cathode made of lithium iron phosphate, lithium cobalt oxide, lithium nickel manganese oxide or active carbon.    DESCRIPTION OF DRAWING(S) - The drawing shows a sectional view of a hybrid bipolar electric energy storage system.    Electrical connections (C1-C3)    Bipolar electrode (1)    Electrically conducting support (2)    Electrodes (3, 4)    Electrochemical accumulator (10)    Supercapacitor (20)