Architecture of interconnected cubic NiCo2S4 decorated mesoporous carbon with self-doped nitrogen based-hydrogel for high performance hybrid supercapacitor

Although the transition metal sulfides have shown persuasive proof and stellar traits for energy storage applications, their real applications still possess some obstacles such as prolonged ionic and electronic transport. Hence, NiCo2S4 decorated a pyrolyzed hydrogel (NiCo2S4@PHG) via facile synthesis is considered a promising electrocatalyst for energy storage devices. The prepared electrode materials were characterized utilizing different analysis techniques like XPS, XRD, FT-IR, TGA, SEM, TEM, elemental mapping and EDX that reveal the crucial role of the hydrogel pyrolysis in creating a homogenous nitrogen-doped carbon matrix. The as-fabricated 0.5 NiCo2S4@PHG nanocomposite was electrochemically examined in a sealed workstation cell and showed a clear battery-type supercapacitor behavior attributed to various redox reactions, porosity, and conductivity that was enhanced by self-doped nitrogen. In contrast, composites based on nickel and cobalt sulfides individually with pure hydrogel demonstrated the superiority of binary metal composites. The 0.5 NiCo2S4@PHG electrode exposed a marvelous specific capacity of 317.9 mAh g−1 and capacitance of 2728.5 F g−1 at a current density of 1 A g−1. A hybrid asymmetric supercapacitor was established by 0.5 NiCo2S4@PHG (cathode) and activated carbon (AC, anode), which brought large energy and power densities of 32.8 Wh kg−1 and 750 W kg−1, respectively. The fabricated cell manifests ultra-high retention of 82.6% at a current density of 20 A g−1 after 10,000 cycles. These outstanding accomplishments hold significant potential for practical energy storage and conversion applications.