Abstract
Abstract Controlling the porosity of carbon-based electrodes is key toward performance improvement of charge storage devices, e.g., supercapacitors, which deliver high power via fast charge/discharge of ions at the electrical double layer (EDL). Here, eco-friendly preparation of carbons with adaptable nanopores from polymers obtained via microwave-assisted cross-linking of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) is reported. The polymeric hydrogels possess porous and foam-like structures, giving excellent control of porosity at the precursor level, which are then subjected to activation at high temperatures of 700–900 °C to prepare carbons with a surface area of 1846 m2 g–1 and uniform distribution of micro-, meso-, and macropores. Then, graphene as an additive to hydrogel precursor improves the surface characteristics and elaborates porous texture, giving composite materials with a surface area of 3107 m2 g–1. These carbons show an interconnected porous structure and bimodal pore size distribution suitable for facile ionic transport. When implemented in symmetric supercapacitor configuration with aqueous 5 mol L–1 NaNO3 electrolyte, a capacitance of 163 F g–1 (per average mass of one electrode) and stable evolution of capacitance, coulombic, and energy efficiency during 10 000 galvanostatic charge/discharge up to 1.6 V at 1.0 A g–1 have been achieved.