Activated green carbon-based 2-D nanofabric mats for ultra-flexible all-solid-state supercapacitor

•Activated 2-D carbon nanofabric was electrospun using lignin as a green precursor.•The low-environment impact solvent (Q3C Class) was explored for electrospinning.•High electrochemical enactment as compared to powder and crushed activated carbon.•Flexible supercapacitor device shows stable performance in different bending modes.•High energy (65.52 Wh/kg), power (1036.27 W/kg) density with high cyclic stability. The present investigation, reports the performance of ultra-flexible activated carbon nanofiber mats (ACNF) as an electrode for all-solid-state supercapacitor application in comparison to activated carbon (AC). AC and ACNF were fabricated by pre-carbonization at 600 °C followed by activation using potassium hydroxide (KOH) at 800 °C. Crushed carbon nanofibers (CA-CNF) were prepared by first crushing the pre-carbonized nanofiber mat, followed by KOH activation. These prepared candidates for the supercapacitor electrodes were characterized and compared using Scanning electron microcopy (SEM) and Brunauer, Emmett and Teller (BET) analysis for morphological, surface area, and porosity differences. Along with these, Raman spectroscopy and I-V studies were carried out to get information about sp2 carbon. Cyclic Voltammetry (CV), Galvanostatic charge-discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS) studies were performed to compare the electrochemical performance of the AC, CA-CNF, and ACNF as electrodes materials for supercapacitors. Among these electrodes, the ACNF mat demonstrates a higher specific capacitance of 203.29 F/g as compared to AC (106.17 F/g) and CA-CNF (166.12 F/g) at the same current density of 1 A/g. Furthermore, an all-solid-state supercapacitor device was fabricated using an ACNF mat due to its high flexibility, stand-alone character, and excellent performance as an electrode. The device exhibits a high energy density of 65.52 Wh/kg and a power density of 1036.27 W/kg with high coulombic efficiency (99.6%) after 10,000 cycles. [Display omitted]