Hierarchical Porous Carbon Microfibers Derived from Tamarind Seed Coat for High-Energy Supercapacitor Application.

Abstract

The overwhelming interest in supercapacitors has led to the search for various carbonaceous materials, leading to hierarchical porous carbons. Herein, we report a natural biomass (tamarind seed)-based hierarchical porous carbon without any template and activated by a facile scheme. The tamarind seed coat-based hierarchical porous carbon possessed a unique configuration, making the material exhibit superior supercapacitor properties. A single carbon fiber hosting a distinctive micro- and mesoporous structure formed a connecting thread between the pores. This unique structure enabled high surface area and high capacitance. The highest surface area obtained by this method was 1702 m2 g–1, whereas the capacitance was 157 F g–1 in 6 M KOH. Further, an ionic liquid-based electrolyte revealed 78 F g–1 at a current density of 0.5 A g–1. Outstanding capacity retentions of 96 and 93% were obtained over 1000 cycles at a current density of 2 A g–1 for aqueous (6 M KOH) and ionic liquid (1-butyl 3-methyl imidazoliumbistrifluorosulfonylimide) electrolytes, respectively. The high charge-storage ability of the porous carbon microfibers (PCMFs) can be ascribed to the coexistence of micro- and mesopores. The power characteristics and the cyclic stability of PCMF materials were appealing in both electrolytes. The synthesis process described is amenable for large-scale applications with less complexity.