Pole, cover plate assembly and battery cell

A cover plate assembly comprising:

• a cover plate;
• a pole comprising
• a first metal part including a first concave portion and a first convex portion, the first convex portion protruding from an opening of the first concave portion along a direction away from the first concave portion,
• a second metal part including a terminal and a second convex portion, the second convex portion protruding outward from the terminal, a second concave portion being disposed around the second convex portion, and
• wherein the first convex portion is embedded in the second concave portion, the second convex portion is embedded in the first concave portion, and materials of the first metal part and the second metal part are different, wherein the pole penetrates through the cover plate, the terminal is located on one side of the cover plate, and an end of the first metal part away from the terminal is located on another side of the cover plate;
• an upper plastic part being disposed between the terminal and the cover plate;
• a lower plastic part being disposed on another side of the cover plate;
• a current collector being connected with the first metal part, wherein the materials of the first metal part is the same as material of the current collector;
• and
• a sealing ring being disposed between the pole and a mounting hole.