Venting device and method for manufacturing the same

A venting device inserted into a sealing part of a pouch of a secondary battery, the venting device comprising:

• a housing inserted between confronting surfaces of the sealing part and sealed together with the sealing part;
• an element made of a metal and disposed in the housing and through which a passage is defined providing gas communication between an inside and an outside of the pouch;
• and
• a ball disposed at an outlet-side of the passage, the ball being configured to open and close the passage, the ball having a lower position contacting the element and an upper position spaced apart from the element,
• wherein, in the element, an edge of an inner circumference of a surface of the outlet-side of the passage is chamfered or filleted so as to face the ball, and
• the element comprises:
• a surface treatment layer formed on the chamfered or filleted surface;
• and
• a contact layer made of a polymer and fused to the surface treatment layer.