Assessing the impact of valence asymmetry in ionic solutions and its consequences on the performance of supercapacitors

Abstract

Molecular dynamics simulations were performed to describe the properties of hypothetical salt electrolytic solutions. The main focus of this work is the valence asymmetry, which in recent years has been considered an important aspect in the physical chemistry of aqueous electrolytes. In general, our results show that the structural, energetic, and dynamic properties respond differently to the asymmetry of ionic solutions, but in all cases, appreciable changes were observed. Graphene supercapacitors based on the investigated electrolytes were studied in light of their electrostatic properties. We observed that the electrode capacitances, positive and negative, were greatly influenced by the presence of cations in the electrical double layer of the negative electrode and by the absence of these cations, in the double layer of the positive electrode. In general, we assess that quantitative variations due to valence asymmetry may indeed be an important factor for the development of new and more efficient electrolytes.