Coating of Low-Cost Asphaltenes-Derived Carbon Fibers with V2O5 for Supercapacitor Application

V2O5-coated, low-cost carbon fibers were produced using asphaltenes and V2O3 as precursors, both industrial byproducts. Asphaltenes can be used without any further treatment to fabricate low-cost carbon fibers. The carbon fibers were coated with V2O5 using a straightforward two-step coating procedure, that is, surface etching of fibers with NH4OH, followed by dipping into a V2O3 solution. This facile process represents a time-saving and low-cost alternative to other metal oxide coating techniques, such as atomic layer deposition, to create fiber-based electrode materials. After annealing, the fibers were homogeneously coated with V2O5 and exhibited porosity. Annealing time and temperature influenced the porosity and structure of the fiber material. The highest surface area (440 m(2) g(-1)) was obtained at the highest annealing temperature. The coated fibers show both micropores and mesopores. The different fiber samples were then utilized as supercapacitors using a 1 M Li2SO4 electrolyte. Specific capacitances of up to 125 F g(-1) at a rate of 0.25 A g-(1 )were achieved. Long-term cycling tests showed a capacitance retention of 89% after 10,000 cycles. A strong surface area dependence for the capacitance and increased pseudocapacitance for higher annealing temperatures are demonstrated.