TOP COVER ASSEMBLY, SECONDARY BATTERY, AND APPARATUS USING BATTERY

The present application relates to the field of an energy storage device, and more particularly, to a top cover assembly of a secondary battery, the secondary battery and an apparatus using a battery. The top cover assembly includes: a top cover sheet provided with an explosion-proof hole; an explosion-proof sheet, a position of the explosion-proof sheet corresponding to the explosion hole; and a fixing member, at least part of the fixing member being located between the top cover sheet and the explosion-proof sheet and connecting the top cover sheet and the explosion-proof sheet; where one of the explosion-proof hole and the fixing member is provided with a protrusion and the other is provided with a first groove, and the protrusion and the first groove are fixed. The explosion-proof hole and the fixing member are fixedly connected through the first groove and the protrusion, and the fixing member is connected to the explosion-proof sheet, so that the connection reliability of the explosion-proof sheet at the explosion-proof hole is enhanced, the sealing effect of the explosion-proof sheet is improved, fluctuation of a starting pressure of the explosion-proof sheet caused by welding is reduced, and the safety performance of the secondary battery is improved.