Manganese oxide/hierarchical porous carbon nanocomposite from oily sludge for high-performance asymmetric supercapacitors

Abstract

We first report on the facile and cost-effective fabrication method of manganese oxide/hierarchical porous carbon (MnO2/HPC) composite from oily sludge waste for supercapacitor application. The composite inherited the hierarchical pore structure and possessed uniform interlaced MnO2 nanowire decoration. Asymmetric supercapacitor was developed using MnO2/HPC composite as positive electrode material and HPC as negative electrode in the neutral Na2SO4 electrolyte. Due to outstanding structure characters and the synergistic effects of the two electrodes, such asymmetric supercapacitor could be cycled reversibly in a prolonged potential difference range of 0–2.0 V in neutral aqueous electrolyte with outstanding specific capacitance and cycle durability. In addition, the MnO2/HPC//HPC asymmetric supercapacitor exhibited maximum energy density of 49.6 W h kg−1 at 500 W kg−1. This study opened up the possibility of solid waste-derived electrode material for applications in high performance asymmetric supercapacitors.