Coal tar residues-based nanostructured activated carbon/Fe3O4 composite electrode materials for supercapacitors

Oxygen-rich activated carbon with a three-dimensional network structure was prepared by chemical activation of coal tar residues with potassium hydroxide and subsequent carbonization treatment. Nanostructured Fe3O4/AC composites were then prepared by simple chemical coprecipitation method and were used as active electrode materials for supercapacitors. The electrochemical behaviors of Fe3O4/AC nanocomposites were characterized by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy in 1.0 M Na2SO3 electrolyte. It was shown that the specific capacitance of Fe3O4/AC nanocomposites reached 150 F g(-1) at a current density of 3.0 A g(-1) and was a great improvement over Fe3O4 or AC alone. Furthermore, as-prepared Fe3O4/AC nanocomposites exhibited long cycle life without obvious capacitance fading even after 1,000 charge/discharge cycles. Compared with pure Fe3O4 and AC, the significant enhanced electrochemical performance of Fe3O4/AC nanocomposites could be reasonably attributed to the positive synergetic effect between Fe3O4 and AC.