Abstract: Provided is a rolled copper foil for a lithium ion battery current collector, which has good adhesion to a negative electrode active material, generates less metal powder during ultrasonic welding, and has a rust prevention property. In the rolled copper foil for a lithium ion battery current collector, a surface of the copper foil has a BTA film, the BTA film has a thickness of 0.6 nm or more and 4.6 nm or less, and the rolled copper foil satisfies the following relationships: 40?wet tension [mN]/m]+thickness of BTA film [nm]×10?80; 0.01?arithmetic average roughness Ra [?m]?0.25; and wet tension [mN/m]?35.

Abstract: The present invention is intended to provide a rolled copper foil for a secondary battery negative electrode current collector which can satisfactorily suppress rupture of the copper foil caused by stress generation or the like due to volume change of an active material. A rolled copper foil for a secondary battery negative electrode current collector, wherein a tensile strength in a direction parallel to the rolling direction is 600 MPa or more, and a breaking elongation in the direction parallel to the rolling direction is 2.0% or more; and wherein a tensile strength in a direction orthogonal to the rolling direction is 640 MPa or more, and a breaking elongation in the direction orthogonal to the rolling direction is 3.5% or more.

Abstract: The present invention is intended to provide a rolled copper foil for a secondary battery negative electrode current collector which can satisfactorily suppress rupture of the copper foil caused by stress generation or the like due to volume change of an active material. A rolled copper foil for a secondary battery negative electrode current collector, wherein a tensile strength in a direction parallel to the rolling direction is 600 MPa or more, and a breaking elongation in the direction parallel to the rolling direction is 2.0% or more; and wherein a tensile strength in a direction orthogonal to the rolling direction is 640 MPa or more, and a breaking elongation in the direction orthogonal to the rolling direction is 3.5% or more.