Self-assembly of biomass microfibers into 3D layer-stacking hierarchical porous carbon for high performance supercapacitors

Biomass served as a promising and renewable carbon source of porous activated carbon for supercapacitors is widely studied due to their abundance, easy carbonization and low cost. However, carbonized biomass, much of which possess 1-dimensional fiber structure, tends to retain its original morphologies and structures after carbonization treatment, thus how to control synthesis process to obtain 3-dimensional porous carbon is a significant research direction. Herein, we provide a facile one-step carbonization/activation of tremella dipped with KOH method to achieve the self-assembly of its wirelike composition into 3-dimensional hierarchical porous carbon. As-prepared tremella-derived layer-stacking hierarchical porous carbon exhibits an outstanding specific capacitance of 299.3 F g⁻¹ at a current density of 0.5 A g⁻¹ in two-electrode system, high capacitance retention of 250.3 F g⁻¹ at a high current density of 20 A g⁻¹, and good cycling stability in 6 M KOH electrolyte owing to its extraordinary hierarchical porous microstructure, high specific surface area and good electrical conductivity. To enlarge the voltage window, this material based symmetric supercapacitors are assembled using organic Et₄NBF₄ as electrolyte, which offer an energy density of 42.4 Wh kg⁻¹ at a power density of 760 W kg⁻¹.