Towering non-Faradaic capacitive storage based on high quality reduced graphene oxide from spent graphite: Direct approach and waste utilization

Abstract

Urban mining of graphite for higher value addition is considered to be a leading requirement for both the economic and environmental benefits. Herein, we adopted a scalable and novel synthetic approach using modified Hummers method to produce reduced graphene oxide (rGO) directly and graphene oxide (GO) using spent graphite material obtained from scraped Lithium-ion battery (LIB) for the first time. During the synthesis of graphene derivatives, all the metal impurities have been completely terminated through higher temperature oxidation thereby excluding the curing step of graphite. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) study clearly manifests that the reduction in lattice d-spacing, absence of impurity phase and removal of oxygen groups confirming the preparation of high-quality rGO framework. The synthesized and thermally reduced GO is used as electrode materials for non-Faradaic super capacitor application in different aqueous electrolytes. In particular, directly synthesized rGO material exhibits the superior capacitance of 156 Fg(-1) in neutral system, which is greater than the thermally reduced GO (90 Fg(-1)) and commercial rGO samples (35 Fg(-1)). The findings demonstrate that the as-proposed one-pot methodology to produce rGO endows with economic and environmental viability and also exhibits high purity, suitable for several commercial applications at the same time invigorating the worth of graphite conversion from fatigued LIBs.