Recently, silicon based supercapacitors have received considerable attention for application in mobile and remote sensing platforms due to their unique properties such as high surface area, low cost, long lifetimes, and excellent charge–discharge capability. These promising energy storage devices store more energy than conventional dielectric capacitors and deliver higher power with longer cycle life than available battery technologies. [1-4]. Recent studies in the field of supercapacitors have focused on the realization of hybrid materials to further improve the energy density of supercapacitors via the introduction of transition metal oxides and conductive polymers, which have pseudocapacitive properties.

Herein, we report the synthesis and the characterization of transition metal-oxide decorated carbonized silicon nanowires (TMO/C/PSiNWs) for high performance supercapacitor electrode materials. Porous silicon nanowires were synthesized using a metal assisted low-temperature wet etching procedure and encapsulated in an ultrathin graphitic carbon sheath by using chemical vapor deposition (CVD) technique. Growth of ultrathin TMO layer on C/SiNWs was carried out by a chemical bath deposition (CBD) method. Scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy studies were performed to characterize of the hybrid electrodes. The energy and power density characteristics of the TMO/C/PSiNW electrodes were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge techniques. All the electrochemical performances were characterized in an 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM-TFSI) ionic liquid electrolyte in a potential range of −0.4−1.6 V vs Ag. Electrochemical measurements revealed that TMO/C/PSiNW showed the significant improvements over the previously reported C/PSiNW in terms of energy density and cycling performance. The enhanced capacitance was attributed to the excellent pseudocapacitive behavior of the TMO._.

References:

[1] J.P. Alper, M.S. Kim, M. Vincent, B. Hsia, V. Radmilovic, C. Carraro, R. Maboudian Journal of Power Sources 230 (2013) 298-302.

[2] M.R. Zamfir, H.T. Nguyen, E. Moyen, Y.H. Lee, D. Pribat, J. Mater. Chem. A 1 (2013) 9566–9586.

[3] J.P. Alper, S. Wang, F. Rossi, G. Salviati, N.Yiu, C. Carraro,R. Maboudian, Nano Lett. 2014, 14, 1843−1847.

[4] P. Huang, M. Heon, D. Pech, M. Brunet, P.L. Taberna, Y. Gogotsi, S. Lofland, J.D. Hettinger, P. Simon, Journal of Power Sources, 225 (2013) 240-244.

Acknowledgements

This study was supported by the Scientific and Technological Research Council of Turkey (TUBITAK) 2219- International Postdoctoral Research Fellowship Program (App. No:1059B191401401), and the National Science Foundation of the United States.