Cylindrical lithium secondary battery

A cylindrical lithium secondary battery comprising:

• a cylindrical battery can having a bottom, a side wall, and an open top;
• an electrode assembly;
• a non-aqueous electrolyte;
• and a sealing plate covering the open top of said battery can that accommodates said electrode assembly and said non-aqueous electrolyte,
• wherein said electrode assembly comprises a strip-like positive electrode and a strip-like negative electrode that are wound together with a porous heat-resistant layer and a separator interposed between the positive and negative electrodes, said positive electrode comprising a positive electrode core member and a positive electrode active material layer carried on each side of the positive electrode core member, said negative electrode comprising a negative electrode core member and a negative electrode active material layer carried on each side of the negative electrode core member, and
• said electrode assembly has a central cavity into which a hollow mandrel is inserted, said hollow mandrel having a slit that extends along the entire length thereof, an outer diameter A of said hollow mandrel and a width B of said slit satisfying the relation:
• 0.1≦B/A≦0.6.