Solid-state carbon-based textile supercapacitors for energy storage applications

In this work, carbon-based conducting electrodes based on two different types of carbon nanofibers (CNF) have been produced by the dip and dry coating method onto cotton substrates. Furthermore, activated carbon (Norit A Supra Eur) and manganese oxide (MnO2) have been subsequenlty added to the CNF-based dip-coated cotton fabrics electrodes and asymmetric supercapacitors have been constructed and tested with the focus of obtaining devices with increased capacitive performance. In particular, the carbon-based active layer was prepared by spreading on the CNF-based electrodes a slurry containing the activated carbon (AC) material, graphite fibres, polyvinylidene difluoride (PVDF) as binder and N,N dimethylacetamide (DMA) solvent, whereas the MnO2 based active layer was prepared by spreading on the CNF-based textile electrodes a slurry formed by MnO2, carbon black, graphite fibers, PVDF and DMA. A solution of 1M Na2SO4 impregnated in porous paper separator (Nippon Kodoshi Corportion, Japan) was employed as neutral aqueous electrolyte. The supercapacitors were electrochemical investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS). The results indicated that with this particular combination of carbon and manganese oxide active layers on CNF-based cotton fabrics it was possible to obtain specific capacitance of 100 F/g and a high specific energy density of 10 Wh/kg.