The electrochemical comparisons of reduced graphene oxide synthesized from pristine and recovered graphite from spent Li-ion batteries

Abstract

Two reduced graphene oxides (rGO) were synthesized using two carbon sources, namely pristine graphite (rGO-PG), and recovered graphite (rGO-RG) (graphite recovered from spent Li-ion batteries) by modified hummers method and followed by the chemical reduction method to compare their supercapacitive performances. Their supercapacitance is found to be highly competitive and comparable with each other, except for their rate capabilities. The rate capability of rGO-RG is found to be inferior compared to rGO-PG. The supercapacitive behavior of both rGO’s was evaluated using five different aqueous electrolytes. The specific capacitance, specific energy, specific power, and columbic efficiencies exhibited by rGO-RG and rGO-PG were superior in the presence of 1 M H₂SO₄ and are 36 F g¹, 7.1 Wh kg¹, 0.88 kW kg¹ and 96.55 %; and 40 F g¹, 7.9 Wh kg¹, 0.66 kW kg¹ and 97.36 %, respectively. Both the rGOs exhibited no deterioration in their performance up to 10,000 continuous charge and discharge cycles at a current density of 10 A g¹; rather, they exhibited enhancement in their performances with an increase in charge and discharge cycles. The enhancement exhibited by rGO-RG is superior to that of rGO-PG, which is 844 % (272 F g¹) higher than its initial performance (29 F g¹).