High-strength copper foil prepared with 2-mercaptothiazoline by direct current electrodeposition

•Strength of 700 MPa is realized in 6 μm thickness Cu foils by 2-mercaptothiazoline.•2-mercaptothiazoline restrains columnar grains and weakens (101) orientation.•2-mercaptothiazoline enhances polarization and increases nucleation density.•2-mercaptothiazoline reduces grain size and roughness to strengthen Cu foils.