Electrode Assembly Configured Such that Pressure Welding Portions of Electrode Tab Welding Portions Have Different Sizes and Ultrasonic Welding Apparatus Configured to Manufacture the Same

Disclosed is an electrode assembly formed in a structure in which a plurality of positive electrodes with bundled positive electrode tabs and a plurality of negative electrodes with bundled negative electrode tabs are alternately stacked, each of the bundles of electrode tabs includes a first surface connected to a corresponding electrode lead and a second surface opposite the first surface, the first surface includes a plurality of first pressure welding portions and a plurality of first non-pressure, the second surface includes a plurality of second pressure welding portions and a plurality of second non-pressure welding portions The area of one of the first pressure welding portions is less than the area of one of the second pressure welding portions.