Microwave rapid synthesis of NiO/Ni3S2@graphite nanocomposites for supercapacitor applications

•NiO@graphite and NiO/Ni3S2@graphite nanocomposites successfully prepared in 60 s by microwave solid-state synthesis.•The capacitance value of NiO/Ni3S2@graphite was 155% higher than that of NiO@graphite at a current density of 1 A g−1.•NiO/Ni3S2@graphite//AC asymmetric supercapacitor exhibited high energy density and exceptional cycling stability. [Display omitted] Electrode materials with graphite flake layer structure decorated with nickel oxide and nickel sulfide nanoparticles (NiO/Ni3S2) have been prepared by one-pot microwave method. When NiO/Ni3S2@graphite synthesized by microwave is compared with NiO@graphite electrode, the former obtains a high capacitance of 768 F g−1 at 1 A g−1, exceeding 72% (446 F g−1 at 1 A g−1) of the latter. After 1000 cycles of the NiO/Ni3S2@graphite electrode, the specific capacitance remained at 692 F g−1 (at 1 A g−1) with a capacitance retention of 90%. Furthermore, NiO/Ni3S2@graphite and active carbon electrodes could be assembled into asymmetric supercapacitor (ASC), which exhibited a specific capacitance of 68.5 F g−1 at 1 A g−1 in 6 M KOH solution. The NiO/Ni3S2@graphite//AC ASC also showed a relatively high energy density of 28.86 Wh kg−1, maximum power density of 0.77 kW kg−1, and exceptional cycling stability (80% retention after 2000 cycles).