Top cover assembly for secondary battery, and secondary battery

A top cover assembly for a secondary battery, comprising:

• a first electrode terminal;
• a second electrode terminal;
• a top cover plate insulated from the first electrode terminal and electrically connected with the second electrode terminal;
• a contact piece attached to and being in direct physical contact with the top cover plate;
• and
• a thermo-deformable piece placed opposite to the contact piece, one end of the thermo-deformable piece being electrically connected with the first electrode terminal, the other end of the thermo-deformable piece being a free end;
• wherein
• when a temperature at which the thermo-deformable piece deforms is not reached and an internal pressure of the secondary battery exceeds a reference pressure, the contact piece deforms under the internal pressure to be electrically connected with the thermo-deformable piece so that the first electrode terminal is electrically connected with the second electrode terminal, and
• when the temperature at which the thermo-deformable piece deforms is reached, the internal pressure of the secondary battery increases, and, when the internal pressure of the secondary battery exceeds the reference pressure, the free end deforms along a direction away from the contact piece, and the contact piece deforms under the internal pressure so that a space is kept between the deformed free end and the contact piece to insulate the thermo-deformable piece from the contact piece.