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

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 super-capacitor (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).