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Microsupercapacitors are attractiveenergy storage devices forintegration with autonomous microsensor networks due to their high-powercapabilities and robust cycle lifetimes. Here, we demonstrate poroussilicon nanowires synthesized via a lithography compatible low-temperaturewet etch and encapsulated in an ultrathin graphitic carbon sheath,as electrochemical double layer capacitor electrodes. Specific capacitancevalues reaching 325 mF cm–2are achieved, representingthe highest specific ECDL capacitance for planar microsupercapacitorelectrode materials to date. [ABSTRACT FROM AUTHOR]

We demonstrate a symmetric supercapacitor by using yttria-stabilized zirconia (YSZ) as the electrolyte and silicon carbide nanowires (SiC NWs) as the electrode. The stacked symmetric SiC NWs/YSZ/SiC NWs supercapacitors exhibit excellent thermal stability and high areal capacitance at temperatures above 300 °C. The supercapacitor functions well at a record high temperature of 450 °C, yielding an areal capacitance of 92 μF cm(-2) at a voltage scan rate of 100 mV s(-1). At this temperature, it is also capable of withstanding current densities up to 50 μA cm(-2), yielding a maximum areal power density of 100 μW cm(-2). Good cycling stability is demonstrated with a capacitance retention of over 60% after 10,000 cycles at the operation temperature of 450 °C and a scan rate of 200 mV s(-1).