Wood based biochar supported MnO2 nanorods for high energy asymmetric supercapacitor applications

Eco-friendly Acacia leucophloea wood sawdust based Biochar (BC) is used as a substrate material to support nanorod-like MnO2 through an easy-to-operate in-situ redox reaction between the biochar and KMnO4. The physical and chemical properties of the prepared materials are characterized by using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) with EDAX, X-ray Photoelectron Spectroscopy (XPS), BET surface area with BJH pore size distribution and bio-logic electrochemical analyzer. The XRD result reveals the bare manganese oxide has tetragonal phase group with the space group of I4/m. FESEM image of BC and BC@MnO2 materials exhibits highly porous nature and bundle of nanomd like morphologies respectively. The XPS result reveals the chemical bonding and oxidation state of BC@MnO2 nanocomposite material. The N-2 adsorption and desorption result reveals that the prepared materials BC, MnO2 and BC@MnO2 exhibit high surface area of 550, 152.3 and 613.8 m(2)/g respectively. Electrochemical properties are characterized by three and two electrode set-up. The BC@MnO2 composite electrode exhibits high specific capacitance of 512 Fg(-1) at 0.5 Ag-1 and cyclic stability of 93% after 10,000 cycles. The assembled ASC cell BC@MnO2//AC delivers high specific capacitance of 209 Fg(-1) at 0.5Ag(-1) and cyclic stability of 97.1% after 10,000 cycles. Further, ASC cell exhibits huge energy density of 74.3 Whkg(-1) and power density of 1996.4 Wkg(-1) at 0.5 Ag-1.