EXPLOSION-PROOF SHEET, TOP COVER ASSEMBLY OF SECONDARY BATTERY, AND SECONDARY BATTERY

An explosion-proof sheet, a top cover assembly of a secondary battery, and a secondary battery are provided. The explosion-proof sheet has a pressure release portion arranged oppositely to the explosion-proof hole, a fixing portion surrounding the pressure release portion and connected to the top cover, a connecting portion located between the pressure release portion and the fixing portion for connecting the pressure release portion to the fixing portion. A thickness of a part of the connecting portion is greater than a thickness of the remaining part of the connecting portion.