Flexible self-charging power system: empowered via direct integration of carbon nanostructures based triboelectric nanogenerators and solid-state supercapacitors

Flexible self-charging power systems (f-SCPSs) have gained much attention in the area of next-generation wearable electronics; however, they suffer from impedance matching issues, which limits effective self-charging. Herein, we demonstrated a unique way of utilizing porous carbon as a nanofiller in active layers of triboelectric nanogenerators (TENGs) and as an electrode in solid-state supercapacitors (SSCs) to develop an effective f-SCPS. The carbon/PDMS TENG device generated a peak-to-peak voltage (V_P-P) of 260 V, a peak power of 151 μW and a power density of 0.24 W m^-2, respectively. The carbon SSC showed ideal capacitive properties, including high capacitance (132.7 µF cm^-2), energy density (11.7 nWh cm^-2) and power density (10 µW cm^-2). The improved energy harvesting properties of the carbon/PDMS TENG and the charge-storage properties of carbon SSCs are discussed in detail. The integrated f-SCPS showed that the carbon/PDMS TENG was able to charge the serially connected carbon SSCs to 2.4 V and is capable of driving a smartwatch as a proof-of-concept towards practical realization.