Surface Diffusion and Adsorption in Supercapacitors

Abstract

The prospect of double layer capacitors relies on the high specific surface area provided by microporosity of carbon. Since there is not enough space within narrow micropores for forming a double layer, recent theoretical/computational studies have aimed at explaining the mechanism in micropores. The problem is that the available models suggest substantial differences in the mechanism of energy storage by microporous and other types of carbon, but the electrochemical behaviors are similar to a significant degree. Here, a conceptual model is proposed empirically, which is in full agreement with the experimental data reported in the literature, to reasonably explain a universal mechanism of all carbon-based capacitors including microporous, mesoporous, graphene, etc. It is described that none of the available models for double layer charging from Helmholtz to Graham is valid for carbon-based capacitors, as no double layer is formed within the micropores, as well as the partial contribution of double layer c...