END COVER ASSEMBLY, BATTERY CELL, BATTERY AND ELECTRIC DEVICE

The embodiments of the present application provide an end cover assembly, a battery cell, a battery and an electric device. The end cover assembly (10) is used for the battery cell (400). The end cover assembly (10) comprises: an end cover body (1); a pressure relief component (2) connected to the end cover body (1), wherein the pressure relief component (2) is provided with a first through hole (21) used for injecting an electrolyte, and the pressure relief component (2) is configured to be actuated when the internal pressure of the battery cell (400) reaches a threshold value so as to relieve the internal pressure of the battery cell (400); and a closing component (3) detachably provided on the pressure relief component (2), wherein the closing component (3) is configured to close the first through hole (21).