HYBRID FOIL WELD JOINT AND WELDING METHODS

A battery cell, a method of welding electrode foils in a battery, and a method of forming a battery cell. The battery includes a foil stack. The foil stack includes a plurality of foil tabs each extending from a current collector and at least one internal terminal lead. The battery further includes a weld joint formed between the plurality of foil tabs and the at least one terminal lead in the foil stack. A portion of the weld joint includes a weld nugget extending across the plurality of foils into the internal terminal lead, and the remainder of the weld joint includes a diffusion bonding zone extending around at least a portion of the weld nugget.