A high energy storage supercapacitor based on nanoporous activated carbon electrode made from Argan shells with excellent ion transport in aqueous and non-aqueous electrolytes. (December 2019) - Boujibar, Ouassim
Highlights: Activated carbons were prepared from waste biomass (Argan shells). Suitable textural properties enabling fast electrolyte diffusion. Excellent storage performances in aqueous and non-aqueous EDLC devices. Abstract: A high-performance supercapacitor electrode was obtained from waste biomass, Argan shells. This electrode was fabricated using a simple activation technique; demonstrating an industry-friendly process, which is capable of having precise control over pore size distribution of the activated carbon derived from a natural resource. The obtained samples exhibited different pore size distributions, based on different activating agents and different activation routes used in the process. Two distinctly different pore size distributions were obtained from a single source and same synthesis routes, only by exploiting the size differences of the activating agents, which are potassium (KOH) and sodium (NaOH) ions respectively. This process enabled a significant enhancement of specific energy, with no or very negligible change in specific power. Thanks to the fact that there was almost no loss in ion diffusion properties within the porous network of the electrodes even after a change in the electrolytes, to the more viscous ionic liquid (Ethyl-Methyl Imidazolium Tetrafluoroborate), from comparatively less viscous aqueous and organic-based electrolytes. This size-controlled activation enabled us obtaining appropriate pore size distribution, which is a combination of a large number of micropores and a sufficient number of mesopores. This provided a very high specific surface area of 2251 m 2 /g with a total pore volume of 1.04 cm 3 /g. Very high specific capacitance of ∼179 F/g in aqueous electrolyte (0.5 M K2 SO4 ) was obtained. The excellent porosity resulted in very high specific energy of ∼65 Wh/kg and high specific power of ∼2 kW/kg in ionic liquid electrolyte for 3.5 V operating voltage. Graphical abstract: Image, graphical abstract