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/Ni 3 S 2 ) have been prepared by one-pot microwave method. When NiO/Ni 3 S 2 @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/Ni 3 S 2 @graphite electrode, the specific capacitance remained at 692 F g −1 (at 1 A g −1 ) with a capacitance retention of 90%. Furthermore, NiO/Ni 3 S 2 @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/Ni 3 S 2 @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).