Unravelling the role of pore structure of biomass-derived porous carbon in charge storage mechanisms for supercapacitors

Abstract

This study presents findings on the production and analysis of activated carbon (AC), which exhibits a significantly expansive surface area derived from readily available and inexpensive agroforestry waste, specifically coconut shells. The carbon materials displayed encouraging features for electrochemical energy storage applications with a high specific surface area (2920 m² g⁻¹), an ordered mesoporous structure (∼2.5 nm), and substantial electronic conductivity. By altering the surface properties of AC materials, they exhibited different energy storage responses while using an ionic liquid as an electrolyte. Electrodes composed of AC sourced from coconut shells demonstrated notably high specific capacitance (78 F g⁻¹) and retained capacitance when assessed within symmetric electrical double-layer capacitors (EDLCs) employing organic electrolytes. Interestingly, the AC cell in an organic electrolyte delivered a specific energy (Es) of 67 W h kg⁻¹ at a specific power (Ps) of 1237 W kg⁻¹ at the current density of 1 A g⁻¹ and still provided Es of 64, 60, 58, 57, and 52 W h kg⁻¹ at Ps of 2477, 3724, 4971, 6218 and 12 480 W kg⁻¹ at the current density of 2, 3, 4, 5 and 10 A g⁻¹. This work demonstrates the effect of different pore volumes on the electrocatalytic activity of AC derived from natural product waste. Our results indicate the feasibility of employing these electrodes for lab-scale applications. Thus, the AC material emerges as a highly promising substance, poised to advance the creation of cost-efficient, environmentally sustainable, high-performance, high-power devices.