Biomass-Derived Activated Porous Carbon from Foxtail Millet Husk to Utilizing High-Performance Symmetric Supercapacitor Applications

This study successfully demonstrates the synthesis of foxtail millet carbon-activated (FMCA) materials using a two-step carbonization process from foxtail millet husk (FMH). The pre-carbonized biomass-derived millet husk was chemically activated with KOH at 500 degrees C and subsequently carbonized in an inert argon atmosphere at 800 degrees C in a tubular furnace. XRD analysis revealed a diffraction peak at 2 theta = 23.67 degrees, corresponding to the (002) plane, indicating the presence of graphitic structures. The Raman analysis of FMCA materials showed an intensity ratio (IG/ID) of 1.13, signifying enhanced graphitic ordering and structural stability. The as-prepared FMC and FMCA electrode materials demonstrate efficient charge storage electrochemical symmetric devices. Electrochemical analysis revealed the charge-discharge curves and a specific capacitance of Csp (FMC//FMC) 55.47 F/g and (FMCA//FMCA) 82.94 F/g at 0.5 A/g. Additionally, the FMCA//FMCA symmetric device exhibits superior performance with a higher capacity retention of 94.89% over 5000 cycles. The results confirm the suitability of FMCA for energy storage applications, particularly in electrochemical double-layer capacitors (EDLCs), making it a promising material for next-generation supercapacitors.