Reduced graphene oxide from dead Li-ion batteries with β-Co(OH)2 as a potential electrode for enhanced charge storage capabilities†

Supercapacitive studies were performed on two composites of reduced graphene oxide (rGO)/β-Co(OH)₂ of the same weight composition, with the difference among them being the graphite source, one being the graphite recovered from spent Li-ion batteries (GC150) and the other being the pristine graphite (GPGC150). Results show that GC150 exhibits superior energy storage performances compared to GPGC150. However, the rate capability of the GPGC150 was found to be higher than that of GC150. Both the composites exhibited better cyclic stabilities up to 10 000 cycles at a current density of 10 A g⁻¹. GC150 exhibited zero deterioration while GPGC150 exhibited 9.23% of deterioration. The energy storage parameters, viz., specific capacitance, specific capacity, specific energy, specific power, and coulombic efficiency, exhibited by GC150 at a current density of 1 A g⁻¹ are 36 F g⁻¹, 43 C g⁻¹, 7.16 W h kg⁻¹, 0.77 kW kg⁻¹, and 94.99%, respectively, in a symmetric two-electrode system. The rGO/β-Co(OH)₂ composites synthesized using recovered graphite as the source for rGO (GC150) exhibit supercapacitance better than their analog that is synthesized using pristine graphite as the source for rGO by the synthetic route followed in the present study.