Fabrication of thick anodic films on 304-type stainless steel for binder-free supercapacitors

Abstract

We report the fabrication of thick nanoporous oxide films on stainless steel (SS) foils via long-term constant-potential anodization at room temperature. The anodization potential of 50 V was employed for 1, 2 and 3 h, respectively to form the anodic films with different thickness. The effects of anodic film thickness on supercapacitance behavior have been further investigated as binder-free electrodes. It is found that the anodic film thickness increases linearly with the anodization time while the electrochemical behaviors of anodic film were not proportionally enhanced with the thickness. Furthermore, the formed anodic layers formed at 50 V/3 h exhibits the highest area capacitance ~ 215 mF cm-2 at 1 mA cm-2, and the capacitance still retained 58.9% of its initial value after 1000 cycles.