Patent ID: 7381500

Claim:
A method of preparing a lithium secondary battery comprising: surface-treating a porous separator to provide a coated weight of a gelled polymer that is less than or equal to 20 mg/cm 2 by impregnating the porous separator with a gelled polymer solution containing an organic solvent and less than or equal to 5 wt % of the gelled polymer based on a weight of the organic solvent such that the gelled polymer solution enters and adheres to surfaces of the pores of the porous separator; interposing the porous separator between a cathode and an anode to prepare an electrode assembly; placing the electrode assembly into a housing; injecting an electrolytic solution into the housing in which the electrode assembly is placed to provide a resultant structure; and sealing and curing the resultant structure, wherein at least a portion of the organic solvent remains in pores of the separator with the gelled polymer after the sealing and curing of the resultant structure.