Electrospun carbon/iron-vanadium oxide nanofibers for high energy density supercapacitors

초록

Highly flexible and conductive carbon nanofibers (CNFs) embedded with pseudocapacitive iron-vanadium oxide (FVO) nanoparticles were fabricated via electrospinning of a metal salt/polyacrylonitrile solution followed by high-temperature annealing (750 degrees C). CNFs have a graphitic structure with defects, which could accelerate electron mobility and the access of electrolytic ions to the multivalent FVO nanoparticles, respectively. Poly (methyl methacrylate) (PMMA) was introduced as a sacrificial polymer to alter the internal structure of the nanofibers and thus enhance the electrolytic ion transport pathways. Terephthalic acid was added to provide flexibility by increasing the cross-linking within the electrospun fibers. The flexible FVO/CNFs exhibited excellent electrochemical performance. The optimal sample had a high areal capacitance of 1058 mF center dot cm-2 at a current density of 2.5 mA center dot cm- 2 and showed 100 % capacitance retention during long-term cycling (10,000 cycles). The capacitance at a high current density of 25 mA center dot cm- 2 was 81.3 % of that at a current density of 2.5 mA center dot cm- 2. Using a wider potential window of 0-1.6 V increased the energy density to 389 mu W center dot h center dot cm-2. The optimal FVO/CNF sample maintained 90 % of its initial capacitance after 200 bending cycles.

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