Surface and Diffusion Charge Contribution Studies of Human Hair-Derived Heteroatom-Doped Porous Carbon Electrodes for Supercapacitors

Owing to the high specific surface area and adjustable pore size distribution, biowaste-derived activated carbon (AC) has lately aroused the interest of researchers in supercapacitor applications. Herein, we employ human hair-derived heteroatom-doped porous AC for supercapacitor applications. Electrochemical assessment of the as-synthesized material is examined in three distinct electrolytes, viz., basic (6 M KOH), neutral (1 M Na 2 SO 4 ), and acidic (1 M H 2 SO 4 ), and shows superior performance in 1 M H 2 SO 4 implying its perfect compatibility in an acidic electrolyte. This finding is corroborated via surface and diffusion charge contribution analysis of the AC sample in different electrolytes. Comparing with 6 M KOH (37.5%) and 1 M Na 2 SO 4 (67.5%), superior diffusion charge contribution is observed in the case of 1 M H 2 SO 4 (79%) electrolyte at 20 mV/s that helps to achieve the highest specific capacitance of 274.5 F/g at 1 A/g. Moreover, the as-fabricated all-solid-state symmetric supercapacitor device delivered a remarkable energy density of 47.4 W h/kg at a power output of 1642.8 W/kg, as well as a long cycle life of 87% after 10 000 charge/discharge cycles. As a consequence, this astonishing finding paves the way for the use of various biowastes for a variety of applications for energy storage.