Secondary battery, battery pack and device using battery

A secondary battery, comprising a shell and an end cover assembly, wherein the end cover assembly covers an opening of the shell to form a housing assembly of the secondary battery, wherein the end cover assembly comprises:

• an end cover, provided with a through hole for injection of electrolyte and an accommodating part, wherein the accommodating part is arranged on a side, far away from the shell, of the end cover and is arranged along a circumferential direction of the through hole;
• a sealing element, sealing the through hole;
• and a cover body, covering at least part of the sealing element, wherein the cover body is rotatable and comprises a limiting part, wherein when the cover body rotates to a first position, the limiting part is located inside the accommodating part to limit separation of the cover body from the end cover, and wherein when the cover body rotates to a second position, the limiting part and the accommodating part are misplaced along the circumferential direction of the through hole, to realize separation of the cover body from the end cover.