Dehydrated Sucrose Nanoparticles as Spacers for Graphene–Ionic Liquid Supercapacitor Electrodes

The addition of dehydrated sucrose nanoparticles increases the gravimetric capacitance of electrochemical double-layer capacitor electrodes produced via the evaporative consolidation of graphene oxide–water–ionic liquid gels by more than two-fold. Dehydrated sucrose adsorbs onto graphene oxide and serves as a spacer, preventing the graphene oxide from restacking during solvent evaporation. Despite 61 wt % of the solids being electrochemically inactive dehydrated sucrose nanoparticles, the best electrodes achieved an energy density of ∼13.3 Wh/kg, accounting for the total mass of all electrode components

Anomalous Capacitance Maximum of the Glassy Carbon–Ionic Liquid Interface through Dilution with Organic Solvents

We use electrochemical impedance spectroscopy to measure the effect of diluting a hydrophobic room temperature ionic liquid with miscible organic solvents on the differential capacitance of the glassy carbon–electrolyte interface. We show that the minimum differential capacitance increases with dilution and reaches a maximum value at ionic liquid contents near 5–10 mol% (i.e., ∼1 M). We provide evidence that mixtures with 1,2-dichloroethane, a low-dielectric constant solvent, yield the largest gains in capacitance near the open circuit potential when compared against two traditional solvents, acetonitrile and propylene carbonate. To provide a fundamental basis for these observations, we use a coarse-grained model to relate structural variations at the double layer to the occurrence of the maximum. Our results reveal the potential for the enhancement of double-layer capacitance through dilution