END COVER ASSEMBLY, BATTERY CELL, BATTERY PACK, APPARATUS AND LIQUID-INJECTION METHOD

The present application provides an end cover assembly, a battery cell, a battery pack, apparatus and a liquid injection method. The end cover assembly includes an end cover plate, including a through hole for injecting electrolyte and a fixing portion arranged around the through hole; a nail body, including an accommodating portion for receiving the fixing portion. The accommodating portion is in a shape of annular and includes two inner walls arranged to be spaced apart from each other in a radial direction of the accommodating portion, and an inner wall and an outer wall of the fixing portion are respectively pressed against and engaged with the two inner walls of the accommodating portion to seal the through hole.