Cap assembly, secondary battery including same, and method for manufacturing cap assembly

A secondary battery, comprising:

• an electrode assembly;
• a case including a bottom part, a sidewall part coupled to the bottom part, and an opening facing the bottom part, the case accommodating the electrode assembly;
• and
• a cap assembly coupled with one end of the sidewall part of the case and sealing the opening,
• wherein the cap assembly includes:
• a cap plate having a through hole and a coating layer on at least a portion of an upper surface of the cap plate;
• a terminal plate including a body part and an inserting part, the inserting part protruding from the body part and into the through hole;
• an insulator between the cap plate and the terminal plate;
• and
• a filler between the inserting part and at least of one of the insulator and the cap plate.

A method for manufacturing a cap assembly, the method comprising:

• interposing an insulator between a cap plate in which a through hole is formed and a terminal plate including an inserting part which protrudes to be inserted into the through hole;
• coupling the cap plate and the terminal plate by pressing the cap plate and the terminal plate with the insulator interposed therebetween;
• and
• disposing a filler in at least a portion of a space in which the inserting part inserted into the through hole is surrounded with the insulator and the cap plate.