In-situ N/O-heteroatom enriched micro-/mesoporous activated carbon derived from natural waste honeycomb and paper wasp hive and its application in quasi-solid-state supercapacitor

Abstract

Natural N/O-heteroatom enriched micro−/mesoporous activated carbons are derived from waste honeycomb (HC) and paper wasps hive (PW) via carbonization and chemical activation. Both the activated carbons are characterized using BET analyzer, XRD, Raman spectroscopy, SEM, TEM, EDS, and XPS analysis. Both of them offered approximately the same BET surface area, but different pore structures which are also confirmed by SEM images. The HC-based activated carbon shows a greater ordering of the carbon structure (from XRD) and more N/O-heteroatoms (from Raman) compared to PW-based activated carbon, indicating the better performance of HC-based AC. Further, two EDLC cells are prepared using ionic liquid incorporated gel polymer electrolyte (GPE) PVdF-HFP/ EMImTCM and activated carbons electrodes derived from honeycomb and paper wasp. The EDLC cells are characterized using electrochemical Impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge techniques. The PWAC-based EDLC cell (Cell#2) has been offered a large specific capacitance of ∼88 F g−1 in comparison to HCAC based EDLC cell (Cell#1) ∼ 66 F g−1. The Nyquist plots of both cells are fitted in the modified Randle circuit and all the parameters associated are estimated using the Zview2 software. The initial performance of Cell#2 is high due to the micropore nature of PW-based activated carbon as compared to HC-based activated carbon, and its value decreases after certain cycles which is confirmed during the cycling tests. Cell#1 (HCAC-based) offered high-rate performance compared to Cell#2 (PWAC) also revealed by EIS studies. It is further confirmed by CV studies that CV profiles of Cell#1 are more rectangular as compared to Cell#2. The voltage range of both cells is optimized and suitability is found to be 1.0 V. The cycle performance of both cells was tested using GCD techniques at 1 A g−1 and found that Cell#1 is more stable (∼72 % of initial capacitance) as compared to Cell#2 at 10000th cycles.