Hybridization of graphene into NiCo2S4 hybrid composites as electrode materials for high performance supercapacitors

Abstract

NiCo2S4 is one of the most promising bimetallic sulfides for use in energy-storage systems, but more studies are needed to endow NiCo2S4 (NCS) with a high electrochemical reaction capability and reversibility. In this work, we present rationally materials design of an optimal NiCo2S4 nanoparticle in a graphene (G) matrix as a NiCo2S4/graphene nanocomposite (NCSG). A uniform composite with NiCo2S4 nanoparticles anchored on graphene sheets is fabricated through an innovative one-step hydrothermal method. The XRD, Raman, XPS, SEM, HRTEM and EDS analyses are performed for characterizing the morphology and microstructure of the as-prepared NiCo2S4/graphene composite. Furthermore, we report the improvements in the materials technology, demonstrating the NiCo2S4/graphene (NCSG) nanocomposite electrode with an excellent specific capacitance of 1500 Fg−1 at 2 Ag−1, high capacitance retention of 85.6 %, and long cycle life of 6500 cycles. The practical application is showcased in an asymmetric supercapacitor with a high active-material loading. Tremendously, the produced NiCo2S4/AC asymmetric supercapacitor has a high energy density of 43.2 Wh kg−1 at a power density of 920 W kg−1.