Patent ID: 7191502

Claim:
A method for producing a current collector for use in a secondary battery consisting of a metal foil provided with a plurality of penetrating holes, each of which has a complicated shape without burrs and satisfies the following expressions: 0.05≦S≦50 1.30≦M/N≦100 where: S is an area expressed in mm 2 of the penetrating hole, M is peripheral length expressed in mm of the penetrating hole, and N is a peripheral length expressed in mm of a virtual circle having the area S of the penetrating hole comprising the steps of: passing a metal foil without a hole through between a concavo-convex roll having a plurality of convex parts and a smoothing roll under a given pressure; converting thereby portions of the metal foil without a hole and pressed by the convex parts of the concavo-convex roll into portions with penetrating holes; and passing the metal foil with the penetrating holes further through between a pair of metal smoothing rolls, whereby burrs produced at each periphery of the penetrating holes are removed.