The structural and electrochemical properties of CNF/MnFe2O4 composite nanostructures for supercapacitors

This work report the structural, morphological and electrochemical properties of carbon nanofibers composited with manganese ferrite (CNF/MnFe2O4) for supercapacitors. The obtained samples were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Brunauer-Emmett-Teller analyzer (BET), thermal gravimetric analysis (TGA), X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The electrochemical properties were investigated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS). By increasing the carbonization temperature from 500 to 700 degrees C, the local structure of MnFe2O4 was found to be partial inverted spinel ferrite with oxidation state of Fe3+ and Mn2+. The crystallite size, surface area, residual content of MnFe2O4, and fraction of Mn ions in tetrahedral site increased with increasing of carbonization temperature. The benefits of sample with maximum surface area, largest crystallite size, highest residual content of MnFe2O4 and high fraction of Mn2+ in tetrahedral site leading to enhanced energy storage. The maximum specific capacitance of 345 Fg(-1) at 2 mVs(-1) (using CV) and 291.87 Fg(-1) at 5 Ag-1 (using GCD) were observed. The fascinating electrochemical properties of CNF/MnFe2O4 composite nanostrucutre makes it a potential candidate for high performance energy storage devices.