BATTERY CELL, METHOD AND SYSTEM FOR MANUFACTURING SAME, BATTERY, AND ELECTRICAL DEVICE

A battery cell may include: a housing having an opening; an electrode assembly, accommodated in the housing; and an end cap, including a cap body and a protruding structure, where at least a part of the cap body may be disposed around the protruding structure and laser-welded to the housing so that the end cap fits and covers the opening. In a thickness direction of the end cap, the protruding structure may protrude from an inner surface of the cap body toward the electrode assembly, and block a laser beam during welding between the cap body and the housing. A first recess may be formed on the end cap at a position corresponding to the protruding structure, and recessed from an outer surface of the cap body toward the electrode assembly.