Solar-powered eco-friendly supercapacitor: A cost-effective approach using pre-carbonized agricultural biowaste-derived porous carbon electrodes for high-performance energy storage

This research introduces a photovoltaic-supercapacitor (PVSCs) hybrid system that can efficiently harvest solar energy and store it. The system is built from a green, low-cost, and novel material: biowaste-derived porous carbon (PBC), which is extracted from agricultural waste through a simple carbonization process. The PVSCs device consists of two essential components: an energy-harvesting dye-sensitized solar cell (DSSC) that achieves a power conversion efficiency of 5.6 %, and an all-solid-state symmetric supercapacitor (ASSC) for energy storage. The ASSC is composed from high-performing PBC materials and a solid gel polymer electrolyte. The PBC material in the ASSC exhibits outstanding performance, with a very high specific capacitance (SpCs) of 456.0 F/g, an energy density of 15.8 Wh/kg, and a power density of 249.5 W/kg. The material also shows superior stability with 88.6 % retention of its capacitance after 10,000 cycles. Under simulated sunlight, the DSSC effectively generates and transfers electricity to charge the ASSC. The integrated PVSCs device demonstrates impressive overall performance, including a power conversion efficiency (η_conversion) of 5.6 %, and an energy storage efficiency (η_storage) of 70.27 %. With an exceptional specific capacitance of 0.724 F/cm², with an overall energy conversion and storage efficiency (η_overall) of 3.935 %. This study effectively demonstrates the utilization of pre-carbonized farm waste to generate high-performance, sustainable energy solutions. The novel PVSCs design presents an exciting path for cleaner energy technologies.