A flexible cable-shaped supercapacitor based on carbon fibers coated with graphene flakes for wearable electronic applications

This work presents a flexible cable-shaped supercapacitor based on carbon fibers (CFs) coated with graphene flakes (GFs) for wearable electronic applications. The CF bundles were adopted as base materials and the GFs were coated on the surface of CFs using a simple dipping method for the enhancement of the specific surface area and the higher conductivity of flexible electrodes. H 2 SO 4 was mixed with poly(vinyl alcohol) (PVA) to form a gel electrolyte, which can prevent leakage. Polydimethylsiloxane (PDMS) was selected as a packaging material to fabricate the proposed flexible supercapacitor due to its flexibility and good thermal and chemical stability. From the electrochemical analysis, the fabricated device exhibited 15.099–6.492 mF/cm 2 of specific capacitance and 2.097–0.902 µWh/cm 2 of energy density in the range of 50–300 mV/s of scan rate. These values were about 1.9 times larger than the supercapacitor without being coated with the GFs. In addition, the specific capacitance showed small difference of 3.4% between straight and twisted positions, which assures the mechanical stability of the flexible cable-shaped supercapacitor.