Synthesis of microcrystalline NiCo 2 S 4 nanorods under ambient temperature and pressure for hybrid supercapacitors

The design and fabrication of transition metal sulfides for supercapacitors have attracted considerable attention in recent years because of their potential for energy storage applications. Conventionally, the synthesis process involved subjecting them to high temperatures and pressures, which can be energy-intensive and environmentally unfriendly. Herein, microcrystalline NiCo 2 S 4 nanorods were prepared under ambient temperature and pressure using a two-step method. The Ni 1/3 Co 2/3 C 2 O 4 nanorods were initially synthesized using the coprecipitation technique, and then the NiCo 2 S 4 nanorods were obtained by sulfurating Ni 1/3 Co 2/3 C 2 O 4 with Na 2 S·9H 2 O under ambient conditions. The NiCo 2 S 4 as a high-performance supercapacitor electrode has been demonstrated. The results exhibited that the prepared NiCo 2 S 4 electrodes have low charge transfer resistance, and a high specific capacitance of 1330.0 F g −1 at a current density of 1.0 A g −1 . Furthermore, a hybrid supercapacitor was assembled using activated carbon (AC) as the anode material and NiCo 2 S 4 nanorods as the cathode material, and the resulting NiCo 2 S 4 //AC device exhibits an impressive energy density of 27.1 Wh kg −1 at a power density of 1.6 kW kg −1 . This work demonstrates a vision for fabricating a microcrystalline NiCo 2 S 4 cathode under ambient temperature and pressure for hybrid supercapacitors.