Tin oxide quantum dots embedded between graphene sheets to improve non-aqueous aluminum ion battery performance

A composite of tin oxide quantum dots (SnO2QDs) and reduced graphene oxide (RGO), was synthesized using the rapid microwave synthesis method and used as cathode material in the non-aqueous aluminum ion battery. In addition, graphene oxide (GO) and RGO were also prepared separately, and the properties of the resulting cathode materials were compared using XRD, FESEM, Raman, and HRTEM. RGO/SnO2QDs, GO, and RGO were mixed separately with a binder at a ratio of 90:10 and the resulting slurries were coated on a graphite sheet. The electrochemical performance of the graphite sheet, GO, RGO, and RGO/SnO2QDs cathodes was investigated using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and charge-discharge tests in an electrochemical cell containing an ionic liquid (AlCl3/Et3NHCl) as an electrolyte and aluminum as an anode. The battery with RGO/SnO2QDs cathode exhibited an excellent specific discharge capacity of 231 mAh g-1 at 2 A g-1 after 300 cycles with a Coulomb efficiency of 98.3 %. Furthermore, after 25,000 charge and discharge cycles at 2.5 A g-1, the Al||RGO/SnO2QDs battery demonstrated a specific discharge capacity of 163 mAh g-1, with a Coulombic efficiency of 89 %. Additionally, the superior battery also displayed impressive speed performance, achieving a specific discharge capacity of 124.6 mAh g- 1 at 4 A g-1, with a Coulombic efficiency of 98.6 %. A comparison of the results of four prepared batteries showed that the synergistic effect of SnO2QDs and RGO layers makes for a suitable cathode material for rechargeable aluminum-ion batteries.