A battery cell, a battery, an electrical device, a manufacturing method, and a manufacturing device are. In some embodiments, the battery cell includes: a shell, where the shell includes a wall; and a pressure relief mechanism, where the pressure relief mechanism is disposed on the wall, the pressure relief mechanism includes a body portion and a fragile portion connected to the body portion, the body portion is configured to connect to the wall, and the pressure relief mechanism is configured to break the fragile portion when an internal pressure or temperature of the battery cell reaches a threshold, so as to release the pressure. The pressure relief mechanism further includes a reinforcement portion disposed in the body portion in a thickness direction of the body portion. The reinforcement portion is configured to reduce deformation of the body portion.