Supercapacitor devices using porous silicon electrodes

Electrical double layer (EDL) supercapacitors have been constructed using gold coated porous silicon (PSi) electrodes in a 0.25 M TEABF₄/PC solution. As a comparison with the PSi, graphite paper, carbon cloth and ITO on glass electrodes have also been tested using the same electrolyte. The capacitors have been characterised using a.c. impedance spectroscopy and cyclic voltammetry (normal staircase mode). Devices using PSi electrodes showed a capacitance of approximately 0.2 mF cm⁻² (equivalent to 5 mF g⁻¹). In comparison, devices based on ITO on glass electrodes had a capacitance of 0.76 mF cm⁻². Those based on graphite-paper electrodes gave 10 mF cm⁻² (equivalent to 131 mF g⁻¹) and those using carbon cloth gave 600 mF cm⁻² (equivalent to 35 F g⁻¹). Paper presented at the 6th Euroconference on Solid State Ionics, Cetraro, Calabria, Italy, Sept. 12–19, 1999.