Top cover assembly of secondary lithium battery

The utility model discloses a secondary lithium battery top cover assembly which comprises a top cover plate, the top cover plate is provided with a liquid injection hole and a sealing piece used forsealing the liquid injection hole, the upper end face of the top cover plate is provided with a welding ring used for being welded to the sealing piece, and the top cover plate is further provided with a patch capable of sealing the welding ring. And the patch can be taken down from the top cover plate, so that the sealing element can be welded with the welding ring. According to the utility model, the patch can effectively protect the welding ring, so that the welding ring is not polluted in the production, transportation and liquid injection processes of the secondary battery, the patch is taken down from the top cover plate after liquid injection is finished, the sealing element is welded with the welding ring, and the welding effect is good due to the smooth and pollution-free surfaceof the welding ring; the s