BATTERY CASING, SINGLE BATTERY, AND BATTERY PACK

The present disclosure provides a battery housing, a battery cell, and a battery pack. The battery housing includes a top cover plate and a cell housing for assembling a positive terminal. The top cover plate is welded at a top opening provided at a top of the cell housing. The top cover plate is in a shape of a flat plate. The cell housing is outwardly expanded at the top opening along a circumferential direction of the top opening and then bent to form a first step section. The top cover plate abuts against and is welded to the first step section.