Designing hierarchical NiCo₂S₄ nanospheres with enhanced electrochemical performance for supercapacitors

Hierarchical nanostructure materials have attracted significant attention due to their fascinating structural features for the application of high-performance supercapacitors. In this report, nanosheets interconnected hierarchical NiCo₂S₄ (NCS) nanospheres were synthesized by a facile hydrothermal method. The growth process was explored by performing different reaction temperature conditions (140, 150, 160, and 170 °C), and their electrochemical properties were studied. The electrochemical properties of NCS products (coated on conductive Ni foam substrate) at different reaction temperatures were measured in a traditional three-electrode electrochemical system. The optimized hierarchical NCS nanospheres (prepared at 150 °C) delivered better electrochemical results due to their synergetic morphological features and higher specific surface area. The NCS-150 nanospheres–based electrode exhibited its maximum specific capacity of 155 mA h g⁻¹ at 2 A g⁻¹ and further showed a good capacity retention value of 115 mA h g⁻¹ at a higher current density of 5 A g⁻¹. Besides, cycling analysis was proceeded up to 4000 cycles to test the practical ability of the designed electrode, and it retained 76% of capacity after performing the cycles. These results demonstrate that the nanosheets interconnected hierarchical NCS nanospheres (prepared at 150 °C) could be a promising electrode material for high-performance supercapacitors.