Cost-effective synthesis of nitrogen self-doped activated carbon with 3D porous honeycomb structure for enhanced supercapacitor electrode performance

This study addresses the prevalent use of chemically synthesized carbon nanomaterials in commercial supercapacitors, accounting for over 80% of deployments, marked by costliness and reliance on non-renewable resources. In response, biowaste is explored as a prospective source of sustainable carbon. The research focuses on converting biomass waste into an economically viable, high-performance electrical energy storage system. Renewable and environmentally benign biomass feedstock is prioritized for cost-effective and sustainable supercapacitor electrode design. A cost-effective three-dimensional (3D) porous honeycomb carbon is synthesized from bamboo shells via carbonization and activation with potassium hydroxide (KOH). The resulting activated carbon exhibits significant porosity and a high specific surface area, validated by Brunauer-Emmett-Teller (BET) analysis. Morphological studies using field emission scanning electron microscopy (FESEM) showcase the 3D honeycomb structure. Structural analyses through Raman spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) further affirm the material’s characteristics. The carbonized bamboo shell-derived electrode demonstrated an outstanding specific capacitance of 310 and 135 F/g at 1 A/g in a three-electrode and two-electrode systems respectively. Remarkably, even after 10,000 cycles at a current density of 2 A/g in a 2 M KOH aqueous electrolyte solution, the electrode exhibited remarkable capacitance retention at 78%. The fabricated symmetric cell demonstrates high values of an energy density of 10.8 Wh/kg and a power density of 720 W/kg at 1 A/g. Utilizing the developed electrode, a symmetric supercapacitor device is successfully demonstrated by illuminating ten red light-emitting diodes (LEDs), showcasing its practical utility in energy storage applications.