Energy storage investigation on regenerated graphite-metal oxide composites from end-of-life LIBs and promising for a closed-loop approach

Abstract

Different metal oxide/graphite composite materials (TiO2/regenerated graphite (RG) and MnO2/RG) were prepared with use of RG from fatigued lithium-ion batteries. The regeneration of spent graphite was done via acetic acid treatment, and the graphite/metal oxide composite was prepared by an ultrasonication route. The structural properties of the as-prepared composite materials are effectively influenced by the introduction of TiO2 and MnO2 particles as evidenced by the variation in the intensity of the diffraction peaks and the appearance of new peaks. The decoration of graphite flakes with metal oxide particles is demonstrated by morphological and mapping analysis. The optimum concentration of MnO2 particles is found to be 10 wt% in a graphite framework and results in good functional properties when compared with RG and a TiO2/RG composite. Finally, the optimized 10 wt% MnO2/RG composite displays excellent charge storage of 184 F/g in 1 M KOH electrolyte, which is greater than for the other graphite composite samples. The impact of MnO2 productively contributes to the excellent capacitance of graphite, which is due to greater grain conductivity, thus reducing the charge transfer resistance and providing a large contact area for storage of ions. As a result of this, a 10 wt% MnO2/RG-based symmetric supercapacitor shows the greatest electrochemical storage, which is 36.78 F/g. Therefore, as-prepared MnO2/RG composite has great prospects for upcoming advanced charge storage devices and supports the re-fabrication of waste material as well as a closed-loop approach.