Preparation of Hierarchical Porous Activated Carbon from Banana Leaves for High-performance Supercapacitor: Effect of Type of Electrolytes on Performance

We demonstrate a facile efficient way to fabricate activated carbon nanosheets (ACNSs) consisting of hierarchical porous carbon materials. Simply heating banana leaves with K2CO3 produce ACNSs having a unique combination of macro-, meso- and micropores with a high specific surface area of similar to 1459 m(2) g(-1). The effects of different electrolytes on the electrochemical supercapacitor performance and stability of the ACNSs are tested using a two-electrode system. The specific capacitance (C-sp) values are 55, 114, and 190 F g(-1) in aqueous 0.5 M sodium sulfate, organic 1 M tetraethylammonium tetrafluoroborate in acetonitrile, and pure ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) electrolytes, respectively. The ACNSs also shows the largest potential window of 3.0 V, the highest specific energy (59 Wh kg(-1)) and specific power (750 W kg(-1)) in [BMIM][PF6]. A mini-prototype device is prepared to demonstrate the practicality of the ACNSs.

Automated summary

This study demonstrates a facile and efficient method to produce activated carbon nanosheets with a high specific surface area and hierarchical porous structure. The supercapacitor performance of the nanosheets in different electrolytes was tested, showing superior performance in an ionic liquid electrolyte.