Abstract: A jelly-roll type electrode assembly, a lithium secondary battery having the same, and a method for manufacturing the same are provided. The electrode assembly comprises a deformation prevention core which simplifies the manufacture of a lithium secondary battery and prevents deformation of the electrode assembly. The electrode assembly comprises positive and negative electrode plates and a separator wound around a deformation prevention core. A positive electrode active material is coated on the positive electrode plate and a negative electrode active material is coated on the negative electrode plate. The separator insulates the positive electrode plate from the negative electrode plate. The deformation prevention core is located near the center of the electrode assembly.

Abstract: The present invention relates to a method for the prepolymerization of ?-olefin in the presence of a catalyst system which comprises (a) a magnesium supported solid complex titanium catalyst and (b) an organometallic compound of metal of Group I or III of the Periodic Table, characterized in that an inert solvent having high viscosity with molecular weight of 300 g/mole or more is used as a reaction medium.

Abstract: The present invention relates to a method for the prepolymerization of &agr;-olefin in the presence of a catalyst system which comprises (a) a magnesium supported solid complex titanium catalyst and (b) an organometallic compound of metal of Group I or III of the Periodic Table, characterized in that an inert solvent having high viscosity with molecular weight of 300 g/mole or more is used as a reaction medium.