Performances of dual carbon multi-ion supercapacitors in aqueous and non-aqueous electrolytes

Abstract

Avocado-seed biomass-derived activated carbon was successfully synthesized by carbonization followed by chemical activation. The synthesized carbon was characterized using various material characterization techniques. The characterization data revealed that the carbon was porous with self-doped heteroatoms. The electrochemical characterizations confirmed that the carbon generated was capable of charge storage, exhibiting a high specific capacitance of 774 F g⁻¹ at a current density of 0.7 A g⁻¹ in the three-electrode cell. The detailed Dunn's method revealed that the charge storage is dominated by the capacitive mode. An aqueous supercapacitor fabricated in the form of the CR-2032 coin cell delivered a specific energy of 21 W h kg⁻¹ at a specific power of 275 W kg⁻¹. For the first time, a dual carbon sodium-ion capacitor (DC-NIC) was fabricated using the avocado seed-derived carbon (AVAC) that exhibited outstanding specific energy of 72.36 W h kg⁻¹ at a specific power of 320 W kg⁻¹, while a dual carbon lithium-ion capacitor (DC-LIC) device exhibited high specific energy of 55.25 W h kg⁻¹ at a specific power of 300 W kg⁻¹ with nearly 100% coulombic efficiency. The fabricated coin cell DC-NIC prototype was demonstrated to power commercial red, green, and blue LED bulbs. The once-charged DC-NIC coin cell could power the commercial green LED bulb for about 16 min.