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

Embodiments of this application provide a battery cell, a method and system for manufacturing same, a battery, and an electrical device. A battery cell according to an embodiment of this application includes: a housing, on which an opening is made; an electrode assembly, accommodated in the housing; and an end cap, configured to fit and cover the opening, where the end cap includes a cap body and a protruding portion around the cap body, the protruding portion protrudes from an inner surface of the cap body toward the electrode assembly, and at least a part of the protruding portion is located in the housing and configured to fit with the housing; and a recessed portion is formed on the end cap at a position corresponding to the protruding portion, and the recessed portion is recessed from an outer surface of the cap body toward the electrode assembly and configured to release a stress while the protruding portion extends into the housing. This application improves the assembling efficiency of the battery cell and enhances safety of the battery cell.