NOVELTY - Manufacturing jelly-roll type electrode assembly involves coating both sides of porous substrate with (in)organic composite layers including inorganic particles and organic polymer as binder, to fabricate composite membrane; and inserting one end of sheet laminate comprising cathode and anode sheet as well as the composite membrane into mandrel, winding the sheet laminate around the mandrel, and removing mandrel.    USE - For manufacturing jelly-roll type electrode assembly having cathode/separation membrane/anode laminate structure, for secondary battery (claimed) e.g. secondary lithium battery.    ADVANTAGE - The method for fabrication of jelly-roll type electrode assembly maintains a low interfacial friction between composite membrane and mandrel, and prevents the composite membrane from released when the mandrel is removed, thus exhibits excellent winding assembly characteristics; decreases failure rate of products and improves productivity. The jelly-roll type electrode assembly provides superior thermal stability and exhibits improved battery performance; increases mechanical strength of secondary battery; inhibits deformation of the electrode assembly; and prevents deterioration in performance of the battery while enhancing safety of the battery. The composite membrane exhibits superior buffer effects on contraction and/or expansion of an electrode during charge/discharge; exhibits desired mechanical strength and excellent dimensional stability, thus preventing contraction of the membrane and internal short circuit damage due to the contraction.    DETAILED DESCRIPTION - Manufacturing jelly-roll type electrode assembly having cathode/separation membrane/anode laminate structure, involves coating both sides of porous substrate with organic/inorganic composite layers including inorganic particles and organic polymer as a binder, to fabricate a composite membrane; and inserting one end of sheet laminate comprising cathode and anode sheet as well as the composite membrane into mandrel, winding the sheet laminate around the mandrel, and removing mandrel, where organic/inorganic composite layer includes microfine pores capable of moderating variation in volume during charge/discharge of secondary battery, and an interfacial friction coefficient between the composite membrane and the mandrel is not greater than 0.28. INDEPENDENT CLAIMS are included for the following:    (1) preparation of composite membrane for secondary battery involving dissolving an organic polymer capable of inducing a binding force between inorganic particles and adhesion of the inorganic particles to surface of substrate, in solvent (first solvent) to prepare a solution; adding the inorganic particles to the prepared solution to prepare an organic/inorganic coating solution; immersing porous substrate in the coating solution through dip-coating, to form coating layers on both sides of porous substrate; and removing the solvent to produce the organic/inorganic composite layer having microfine pores;    (2) a jelly-roll type electrode assembly fabricated comprising an organic/inorganic composite layer including microfine pores capable of moderating variation in volume during charge/discharge of secondary battery, is formed on both sides of a porous substrate for fabricating a separation membrane, and the organic/inorganic composite layer has an interfacial friction coefficient relative to a mandrel used for manufacturing the jelly-roll type electrode assembly of not greater than 0.28; and    (3) a secondary battery having the jelly-roll type electrode assembly built in a battery case.