End cover assembly and battery monomer

The utility model discloses an end cover assembly and a battery monomer, the end cover assembly comprises an end cover, the end cover is provided with an accommodating cavity and a sealing structure arranged in the accommodating cavity of the end cover; a through hole is formed in the bottom of the accommodating cavity; a liquid injection cavity is formed in the valve body in a hollow mode, and at least one liquid injection hole communicated with the liquid injection cavity is formed in the outer surface, close to the through hole, of the valve body. The valve body can move in the axial direction of the containing cavity under the action of external force so as to change the position of the liquid injection hole relative to the through hole. According to the end cover assembly, the relative positions of the liquid injection hole and the through hole are adjusted in a pressing mode through the sealing structure movably connected with the end cover, so that opening and closing of the sealing structure are achie