Crystallinity-controlled, kenaf fiber-derived activated carbons with high mesopore ratio for high-rate supercapacitors with aqueous and organic electrolytes
摘要
This study reports the development of high-performance supercapacitor electrodes derived from biomass kenaf fibers (KFs) through hydrothermal pretreatment and steam activation. The hydrothermal treatment significantly enhances the crystallinity of cellulose, resulting in improved thermal and structural stability. This enhanced crystallinity effectively mitigates common issues, such as pore collapse and structural degradation during prolonged steam activation. Notably, hydrothermally treated KFs (HKFs) maintain structural integrity even after 3 h of steam activation at 900 °C. The resulting activated carbon (HKF-200-3) exhibits a high surface area of 1675.1 m² g− 1 and a mesopore ratio of 47.2%. The HKF-200-3 based coin cell delivers a specific capacitance of 28.9 F g− 1 (at 1 A g− 1) in 6 M aqueous KOH electrolyte and 25.2 F g− 1 (at 1 A g− 1) 1 M DMPBF4/AN organic electrolyte, demonstrating excellent rate capability. The device achieves an energy density of 25.99 Wh kg− 1 and a power density of 675 W kg− 1, along with 82% capacitance retention after 100,000 cycles. This work presents a promising strategy for the preparation of crystallinity-controlled biomass-derived activated carbons for sustainable energy storage applications.