Asymmetric supercapacitor device performance based on microwave synthesis of N-doped graphene/nickel sulfide nanocomposite

Nickel sulfide (NiS) and Nitrogen-doped Graphene/NiS nanocomposite (NG/NiS) are prepared via green microwave synthesis route as electrode materials for supercapacitors. As-prepared materials are examined using XRD, Raman, XPS, SEM, EDX and elemental mapping characterization techniques to obtain the information regarding their structure, complex formation, morphology and elemental presence. The electrochemical investigations like CV, GCD and impedance analysis suggest that NG/NiS is an excellent electrode material with a specific capacitance of 1467.8Fg(-1) at 1Ag(-1). In asymmetric configuration of NG//NG/NiS, with polyurethane foam as the separator soaked with 6M KOH and graphite sheet as the current collector, the composite produces the energy density of 66.6Whkg(-1) at a power density of 405.83Wkg(-1) with a cyclic stability of 86.6% for 5000 cycles. The high electrochemical performance is because N-doped graphene houses NiS nanoflake clusters, and together they demonstrate an impressive performance for supercapacitors.