2.1. μSC fabrication
Fig. 1 reports the schematic picture of the flexible, IL-based μSC. Two ns-C electrodes of 1 cm2 area each and thickness of 320 nm or 500 nm, separated by E-64-c 2 mm gap, were deposited by SCBD over a Mylar substrate (20 μm thickness) previously coated by a thin metallic film (platinum with ca. 200 nm thickness) as current collector. Such simple μSC design aims to be considered as a benchmark for further optimization (in terms of electrode geometric area and size, electrode spacing and current collector material). Hereafter, the labels μSC-320 and μSC-500 indicate the supercapacitors with ns-C layers of 320 nm and 500 nm, respectively.
Fig. 1. Schematic picture of the flexible, IL-based μSC fabricated by SCBD.Figure optionsDownload full-size imageDownload as PowerPoint slide
The as-deposited ns-C electrodes were, then, coated by a fiber glass separator (Whatman,GF/F, dried before use) soaked with the N1113TFSI (99.5%, Solvionic, used as received) IL. At RT, the IL features an electrochemical stability window of 5.7 V and a conductivity of 9.3 mS cm−1. A silver foil and an activated carbon fabric (Spectracorp 2225, 2500 m2/g) were vertically stacked with the μSC electrodes and separated from them by the separator and used as quasi-reference electrode and counter electrode, respectively, for the electrochemical tests in 3-electrode mode. The area exposed to the electrolyte of the silver foil and the activated carbon fabric was ca. 0.5 × 0.6 cm2. The μSCs were assembled in dry box (MBraun, Atmosphere, H2O and O2 <1 ppm).