Cross-assisted NCS and rGO hetero-architecture for hybrid symmetric and asymmetric supercapacitor electrodes

Abstract

Herein, we report the optimization of zero-dimensional (0D) nickel cobalt sulfide (NCS) nanoparticles and two-dimensional (2D) reduced graphene oxide (rGO) nanosheets as excellent electrodes for high-performance supercapacitors. The well-optimized NCS, rGO, and their composite taken in weight ratio of NCS-rGO(2:1) provides surface area of 40.02, 10.13, and 12.02 m2/g, respectively, which offers more active sites for electrochemical reactions. The augmented presence of +4 oxidation states of Co and the +3 oxidation state of Ni in the NCS-rGO(2:1) composite delivers high specific capacitance (Cs) values. Post electrochemical testing, NCS-rGO(2:1) exhibits an excellent Cs of 1202.57 F/g at 2 A/g and cyclic stability of ∼ 80 % after 10,000 cycles at 5 A/g. Three different devices are prepared with symmetric and asymmetric configurations of NCS, rGO, and NCS-rGO(2:1) electrodes. The symmetric device NCS-rGO(2:1) shows the best performance in terms of Cs of 310.45 F/g at 2A/g. However, the asymmetric device with rGO and NCS-rGO(2:1) as electrodes delivered the highest energy density of 70.9 Wh/kg (at 16.1 kW/kg) and power density of 163.6 kW/kg (at 54.5 Wh/kg). Overall, our finding corroborates that rich redox active NCS-rGO(2:1) composites are excellent candidates to synergistically assist each other to provide supercapacitor devices with higher energy density. © 2025