High yield activated porous coal carbon nanosheets from Boropukuria coal mine as supercapacitor material: Investigation of the charge storing mechanism at the interfacial region

Here, we report a porous carbon material derived from coal of Boropukuria, Dinajpur, Bangladesh that has been used for fabricating high-power supercapacitor. The activated coal carbon nanosheets (ACCNs), prepared using simple pyrolysis, had a high yield (60%), and contained O and N heteroatoms, along with a hierarchical porous network of micro, meso, and macro pores. Surface morphology, elemental composition, crystallite size, and porous network of the ACCNs have been studied using FESEM, XPS, Raman, and N2 adsorption-desorption analysis. An operating potential window of 1.1 V was obtained in 1 M KCl neutral electrolyte solution. At 2.25 A/ g the calculated specific energy was similar to 39.04 Wh/kg, along with a high specific power of similar to 1237.5 W/kg. The ACCNs material was able to retain specific energy of similar to 22.92 Wh/kg and specific power of similar to 41,250 W/kg at a high current density of 75 A/g. The contribution of capacitive (non-Faradic), and diffusion intercalation (Faradic) current has been investigated using Cottrell and Dunn's equations. The ACCNs material was used for making a coin cell prototype supercapacitor device and tested with a light emitting diode (LED).