Curcuma Longa Derived Heteroatom‐Self‐Doped Porous Carbon for Cost‐Effective Solid‐State Supercapacitors

Abstract The cost‐effective synthesis of supercapacitors is a significant challenge in energy storage research. This study introduces a sustainable and cost‐effective method for synthesizing biomass‐derived carbon for solid‐state supercapacitor fabrication. Turmeric (Curcuma longa) plant waste is carbonized at three distinct temperatures (500, 600, and 700 °C for 3 hours), and the resulting carbon is characterized to determine the optimal carbonization conditions. Physicochemical characterization revealed the presence of multiple heteroatoms, which may contribute to enhanced capacitance. Electrochemical studies showed that the carbonized material at 600 °C achieved the highest specific capacitance of 110.04 F/g at 0.1 A/g current density. After activation, the specific capacitance increased to 188 F/g at 0.1 A/g current density. A solid‐state supercapacitor was assembled using the synthesized activated carbon and PVA/H₂SO₄ gel‐type electrolyte. The resulting device exhibited an impressive specific capacitance of 92.33 F/g at 0.1 A/g, a power density of 4295.28 W/kg, and a cycling stability of 97.42 %. This supercapacitor shows promising potential as an economical and sustainable energy storage solution for portable electronics.