Spray Deposition of Supercapacitor Electrodes using Environmentally Friendly Aqueous Activated Graphene and Activated Carbon Dispersions for Industrial Implementation

Abstract

A spray gun machine was used to deposit high-surface-area supercapacitor electrodes using green non-toxic aqueous dispersions based on different kinds of high specific surface area nanostructured carbon materials: activated graphene (a-rGO) and activated carbon (AC). Tuning the spray conditions and dispersion formulation allowed us to achieve good adhesion to stainless-steel current collectors in combination with high surface area and a satisfactory mechanical stability of the electrodes. The specific surface area of approximately 2000 m2/g was measured directly on a-rGO and AC electrodes showing only around a 20 % decrease compared to the precursor powder materials. The performance of the electrodes deposited on stainless-steel and aluminum current collectors was tested in supercapacitor devices using three electrolytes. The electrodes were tested in an “as-deposited” state and after post-deposition annealing at 200 °C. The spray deposition method and post-deposition annealing are completely compatible with roll-to-roll industrial production methods. The a-rGO demonstrated superior performance compared to AC in supercapacitor electrodes with gravimetric capacitance, energy, and power density parameters, which exceed commercially available analogues. The formulation of the dispersions used in this study is environmentally friendly, as it is based on only on water as a solvent and commercially available non-toxic additives (graphene oxide, fumed silica, and carbon nanotubes).