A current collector in the form of a conductive substrate subjected to a special chemical etch to provide the current collector having a multi-thickness structure, is described. The multiple-thickness current collector structure provides an electrochemical cell with increased charge capacity per volume while enabling a robust weld connection thereto. The current collector has a frame and comprises within an inner perimeter of the frame, first strand structures that intersect second strand structures to provide a plurality of openings or interstices bordered by the strands. At least one tab portion having a thicker distal portion spaced from a thinner proximal tab portion that extends from an outer perimeter of the frame.