A hierarchical porous carbon material from a loofah sponge network for high performance supercapacitors

Abstract

Environmentally friendly, low-cost and renewable biomass is a promising raw material for a high-performance supercapacitor electrode material. Herein, high surface area, hierarchical porous carbon materials were obtained by a carbonization and activation process of a loofah sponge. The specific surface area, pore volume and the pore size distribution of the porous carbon were controlled by adjusting the activation temperature and suitable activation agents. The results show that the carbon materials possess a high proportion of micropores and a few mesoporous structures. Amazingly, among them, the carbon materials prepared at 800 °C with an optimal structure and high surface area (1733 m² g⁻¹) have an outstanding specific capacitance of 304 F g⁻¹ at a current density of 1 A g⁻¹ and excellent rate capability (60.2% capacitance retention at a current density of 50 A g⁻¹). The enhanced electrochemical performance is attributed to the large surface area, good electrical conductivity, and fast charge transfer. Hierarchical porous carbon materials demonstrate superior good cyclic stability such as high capacitance retention of 98% over 10 000 charge–discharge cycles in a 6 M KOH electrolyte. Notably, in the two-electrode symmetric supercapacitors, the energy density could be up to 10 and 64.4 W h kg⁻¹ at a power density of 500 W kg⁻¹ and 11.3 kW kg⁻¹ in aqueous and organic electrolytes, respectively. Our results indicated that the strategies developed here would provide a novel route for the synthesis of porous carbon materials from a low-cost loofah sponge and show the possibility for application in energy storage.