End cap assembly, battery cell, battery, and electrical device

An end cap assembly, a battery cell, a battery, an electrical device, and a method and device for manufacturing a battery cell are provided. The end cap assembly includes an end cap and a pressure relief mechanism. The pressure relief mechanism is connected to the end cap. The pressure relief mechanism is configured to: keep in a first pressure relief state when an internal pressure or temperature of the battery cell is greater than or equal to a first threshold and less than a second threshold, so as to release the internal pressure of the battery cell; and keep in a second pressure relief state when the internal pressure or temperature of the battery cell is greater than or equal to the second threshold, so as to release the internal pressure of the battery cell.