Cap assembly for cylindrical secondary battery comprising current interrupt device coated with insulating material on outer circumference surface

A cap assembly loaded on an open upper end of a metal battery can of a cylindrical secondary battery, the cap assembly comprising:

• a top cap at an uppermost end of the cap assembly and including a positive electrode terminal having an outward protruding structure;
• a safety vent under the top cap and electrically connected to the top cap via a safety vent for discharging gas;
• a current interrupt device configured such that a portion of an upper surface of the current interrupt device is connected to the safety vent and a portion of a lower surface of the current interrupt device is connected to an electrode lead of an electrode assembly, the portion of the current interrupt device connected to the safety vent being configured to rupture when high pressure is generated in the battery, whereby the current interrupt device is separated from the safety vent to interrupt a flow of current;
• a current interrupt device (CID) gasket coupled to the current interrupt device so as to wrap an outer circumferential part of the current interrupt device excluding portions of the current interrupt device that are connected to electrode tabs and the safety vent to secure an electrical insulation property of the current interrupt device;
• and,
• an insulative coating layer of an electrically insulative material on the outer circumferential part of the current interrupt device, and
• wherein the insulative coating layer is continuously formed on an outer circumferential surface of the current interrupt device and on portions of an upper surface and a lower surface of the current interrupt device that are adjacent to the outer circumferential surface of the current interrupt device, and wherein the insulative coating layer is absent at a center of the upper and lower surfaces of the current interrupt.