NOVELTY - An electrochemical component comprises an electrode assembly (4) including a positive electrode formed of a strip-shaped positive current collector coated, with a positive electrode active material, and a negative electrode formed of a strip-shaped negative current collector coated, with a negative electrode active material, a positive and a negative lead (9, 10) bonded to the positive and negative electrode, respectively.    USE - The electrochemical component is used as a battery, i.e. lithium ion rechargeable battery, or an electric double layer capacitor. It is useful for a driving power source of a power tool or an electric vehicle.    ADVANTAGE - The current collection efficiency from an electrode assembly is excellent. Electrical loss and a temperature increase during a high-rate charge/discharge are prevented.    DETAILED DESCRIPTION - An electrochemical component comprises an electrode assembly that is accommodated in a case (12) with an electrolyte, the electrode assembly including a positive electrode formed of a strip-shaped positive current collector coated with a positive electrode active material, and a negative electrode formed of a strip-shaped negative current collector coated with a negative electrode active material, the positive and negative electrodes being wound around a separator interposed between them, a positive lead bonded to the positive electrode serving as an external positive connection terminal (21), a negative lead bonded to the negative electrode serving as an external negative connection terminal, where positive electrode includes an exposed current collector portion with a predetermined width at least at one end in a width direction, where the positive electrode active material has not been coated, the negative electrode includes an exposed current collector portion with a predetermined width at least at the other end in the width direction, where the negative electrode active material has not been coated, the separator has a width that is smaller than a width of the positive and negative electrodes, the positive and negative electrodes with the separator interposed between them being wound around to form the electrode assembly having an ellipsoidal cross-section, and the exposed current collector portion of the positive electrode protruding beyond the separator from one end being pressed in a shorter side direction of the ellipsoidal cross-section, and being welded to form a welding joint, the exposed current collector portion of the negative electrode protruding beyond the separator from an other end pressed in the shorter side direction of the ellipsoidal cross-section being welded to form a welding joint.    DESCRIPTION OF DRAWING(S) - The figure is a cross-sectional view showing the configuration of a lithium ion rechargeable battery.    Electrode assembly (4)    Positive and negative lead (9, 10)    Case (12)    External positive connection terminal (21)