Dielectric-Barrier-Discharge Jet Treated Flexible Supercapacitors with Carbon Cloth Current Collectors of Long-Lasting Hydrophilicity

A low-temperature (<30 °C) He dielectric-barrier-discharge jet (DBDjet) is applied to treat screen-printed reduced graphene oxide (rGO)/polyaniline (PANI)/chitosan (CS) nanocomposite flexible gel-electrolyte supercapacitors (SCs) with atmospheric-pressure plasma jet (APPJ)-processed carbon cloth current collectors. The APPJ-treated carbon cloth retained it hydrophilicity for more than 23 weeks. By contrast, carbon cloth furnace-treated at similar temperatures for 30 s and 30 min retained its hydrophilicity for only 6 h and 4 weeks, respectively. Therefore, APPJ treatment benefits the long-term stability of SCs with carbon cloth current collectors. Without substantial heating, the reactive plasma species of the He DBDjet can improve the hydrophilicity of screen-printed rGO/PANI/CS nanocomposites, thereby increasing the SC’s capacitance value. X-ray photoelectron spectroscopy results reveal increased –COOH and C–N contents after He DBDjet treatment, thus explaining the improved hydrophilicity. Galvanostatic charging-discharging measurements demonstrate that the capacitance is improved by 181% after two He DBDjet scans. The capacitance value decreases by only 0.2% after a 10000-cycle CV stability test. No apparent degradation is observed after a 1000-cycle mechanical bending test.