Nitride Supercapacitors: Contribution of Surface Oxide to Charge Storage
We have previously demonstrated excellent charge storage behavior of nanoparticulate vanadium nitride on account of the surface reactions occurring on the surface of the oxide exo-shell. However, there is limited understanding into the exact nature of the charge storage behavior and its dependence on the synthesis and processing route. In the present work, we explore the effect of materials processing and electrode properties on the capacitive charge storage in VN based supercapacitors. Dependence of capacitance on particle and electrode properties are evaluated and reported here-in. Tailoring the particle size, crystallinity and porosity are of paramount importance to achieve high capacitances at high scan rates. To gain a fundamental understanding into the charge storage mechanism of nitride materials shown in Figure 1, slurries of the nitride were cast on nickel current collectors and characterized used various materials and electrochemical characterization techniques including X-ray photo-electron spectroscopy (XPS), cyclic voltammetry and electrochemical impedance spectroscopy. Results of these studies will be presented and discussed.
1. P. Simon and Y. Gogotsi, Nature Materials, 7, 845 (2008).
2. J. R. Miller, Science, 335, 1312 (2012).
3. R. Kötz and M. Carlen, Electrochimica Acta, 45, 2483 (2000).
4. M. Conte, Fuel Cells, 10, 806 (2010).
5. J. W. Long, K. E. Swider, C. I. Merzbacher and D. R. Rolison, Langmuir, 15, 780 (1999).
6. B. E. Conway, Journal of the Electrochemical Society, 138, 1539 (1991).
7. B. E. Conway, Electrochemical Supercapacitors: Scientific Fundamentals and Technological Applications, Kluwer Academic/Plenum Publishers, New York (1999).
8. C. C. Hu and T. W. Tsou, Electrochemistry Communications, 4, 105 (2002).
9. J. M. Miller, B. Dunn, T. D. Tran and R. W. Pekala, J. Electrochem. Soc., 144, L309 (1997).
10. M. Toupin, T. Brousse and D. Belanger, Chemistry of Materials, 14, 3946 (2002).