Biomass-based porous carbon from trachycarpus fortunei silk with the hierarchical oxygen-enriched structure for high performance flexible all-solid-state supercapacitor

Abstract

Hierarchical porous carbons with diverse pore scales are commonly chosen as electrode materials for high-performance supercapacitors due to their excellent electrochemical properties. Herein, a novel synthetic method, dilute H2SO4 pretreatment coupling with subsequent KOH activation, is adopted to prepare hierarchical oxygen-enriched porous carbon using trachycarpus fortunei silk (TFSPC) waste as the raw material. The optimized TFSPC2 possesses a 2049 m2 g−1 specific surface area, 1.58 cm3 g−1 total pore volume, and 22.54 at% oxygen-containing doping. Benefiting from such characteristics, the TFSPC2 electrode exhibits an excellent specific capacitance of 469 F g−1 at 0.5 A g−1 and remarkable cycling stability of only 4.94% capacitance decay even after 20000 uninterrupted cycles in a 6 M KOH electrolyte. Furthermore, the assembled flexible symmetric supercapacitor device TFSPC2//TFSPC2 achieves a high energy density of 14.60 Wh kg−1 in a potential range of 0–1.3 V when the power density is 320 W kg−1. More importantly, the TFSPC2//TFSPC2 device demonstrates superior mechanical flexibility and maintains 88.70% capacity retention even through 2000 cycles (90°) of reduplicative bending/recovering. The research provides a low-cost, green, and renewable strategy for the synthesis of hierarchical porous carbons for supercapacitors.