Top Cover Assembly of Secondary Battery and Secondary Battery

The present disclosure relates to a top cover assembly of a secondary battery and a secondary battery, wherein the top cover assembly includes a top cover plate, provided with a through hole; an electrode terminal, covering the through hole; an insulating plate, wherein at least part of the insulating plate is arranged on a side of the top cover plate away from the electrode terminal; a seal, wherein at least part of the seal is arranged between the top cover plate and the electrode terminal; and an insulator, wherein at least part of the insulator is arranged between the top cover plate and the insulating plate; wherein the insulator and the seal at least jointly enclose a side wall of the through hole and an area, close to the through hole, on an upper surface of the top cover plate.