US Patent 7763378 Cylindrical cell and manufacturing method thereof

A cylindrical battery includes an electrode plate assembly, a positive electrode collector welded to a projecting portion of a core material for a positive electrode plate and a negative electrode collector having a plurality of projections at its lower surface. The negative electrode collector is also welded to a projecting portion of a core material for a negative electrode plate at its upper surface. The cylindrical battery further includes a metal case for accommodating the electrode plate assembly. The projections of the negative electrode collector are welded to an inner bottom surface of the metal case. The projections of the negative electrode collector are arranged at a plurality of locations in a region between a portion opposed to a hollow cylindrical portion of the electrode plate assembly and a peripheral portion.