Silicon carbide coated silicon nanowires as robust electrode material for aqueous micro-supercapacitor

The development of passivated silicon nanowire (SiNW) based micro-supercapacitor electrodes for on-chip applications using an environmentally benign aqueous electrolyte is reported. The SiNWs, produced by low-temperature (50 degrees C) electrochemical etching, corrode during charge/discharge cycling in the aqueous environment, but upon coating with a silicon carbide passivation layer, the corrosion is mitigated. The as-formed materials are in electrical contact with the substrate, requiring no additional current collector. The passivated NWs achieve capacitance values up to similar to 1.7 mF/cm(2) projected area (comparable to state-of-the art carbon based micro-supercapacitor electrodes), exhibit robust cycling stability, and maintain capacitive behavior over a wide range of charge/discharge rates. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4704187]