This invention relates to a Pb storage cell including a cell cover and at least a monomer cell including a first but-welded piece, a base of the first butt-welded piece at the bottom of the first but-welded piece, a second but-welded piece and a base of the second but-welded piece set at the bottom of it, in which, a holding groove for holding the two but-welded pieces is set in the cell cover, said Pb storage cell also includes at least a device for preventing pole-inversion during installation.