Adsorption of tetrachloroaluminate ion on graphene quantum dots

Abstract

The important thing in the mechanism of aluminium ion battery is the fast adsorption of tetrachloroaluminate [AlCl4]- on intercalation sites of bulk graphite which can increase the efficiency and lifetime of the battery. In this study, we modeled graphene quantum dots (GQDs) as cathode material. For the adsorption of [AlCl4]-, coronene (C24H12) and circumcoronene (C54H18) were used as the model of GQDs with three types of adsorption sites and standing positions. The charge of GQDs was modified to be 0 and +1 to address discharging and charging conditions. The distance between chlorine atom and carbon atom of GQDs was found to be between 3.08-3.37 Å. The most stable position for adsorption of [AlCl4]- on GQDs is “H1” (hollow site at center of GQD) in the charging condition, with the adsorption energy of -65.24 kcal/mol, and the distance between chlorine atom and carbon atom is 3.29 Å. This adsorption corresponds to the cell potential of 3.66 V. GQDs can thus be recommended as a cathode material for aluminum ion battery.