Sputtered Synthesis of MnO2 Nanorods as Binder Free Electrode for High Performance Symmetric Supercapacitors

Among numerous active electrode materials, manganese oxides are promising electrodes in supercapacitors. Manganese oxides research has thus far focused on the synthesis of one-dimensional (1-D) metal oxide nanostructured materials, which can have superior electrochemical performance. Several chemical methods are used to synthesize metal oxide nanostructured which involve toxic reagents, solvents and introduction of byproducts. However, physical method offers an eco-friendly path to develop contamination free 1-D metal oxide nanostructured materials. Here, we report the fabrication of binder free supercapacitor electrode of MnO2 nanorods on Nickel (Ni) coated porous anodic aluminum oxide (AAO) by DC magnetron sputtering for first time. Ni coated porous AAO substrate act as excellent current collector, enhancing the specific capacitance of MnO2 to 649 F/g. The binder free symmetric supercapacitor device delivered a high areal capacitance (112.6 mF/cm2), specific capacitance (194.23 Fg−1), good cyclic ability (89.83%) retention in capacitance after 5000 cycles), energy density (4.2 Whkg−1), and power density (1.4 kWkg−1 at 0.718 Whkg−1). These outstanding electrochemical performances, suggest their tremendous potential as supercapacitor electrode in energy storage application.