Facile synthesis and electrochemical properties of sheet-rod-sheet structured NiCo₂S₄/EG/Ti₃C₂T_x nanocomposites

Electrode materials with outstanding stability and electrochemical activity are ideal for high-performance supercapacitors. Herein, we developed a simple two-step method for fabricating NiCo₂S₄/EG/Ti₃C₂T_x nanocomposites with a sheet(2D)-rod(1D)-sheet(2D) structure. The NiCo₂S₄ rods were embedded into the expanded graphite (EG) sheets via an in-situ hydrothermal method, then the Ti₃C₂T_x sheets were assembled with NiCo₂S₄/EG by an electrostatic self-assembly method. The obtained NiCo₂S₄/EG/Ti₃C₂T_x nanocomposites exhibited a synergistic effect among the components. The addition of EG inhibited the volumetric effect of NiCo₂S₄ during charging and discharging processes, while the high conductivity of Ti₃C₂T_x promoted charges transfer. The rod-like structure of NiCo₂S₄ effectively inhibited the self-stacking of Ti₃C₂T_x sheets. Consequently, the optimized composite exhibited an excellent specific capacitance of 1837.9 F·g⁻¹ at a current density of 1 A·g⁻¹. Additionally, the composite electrode exhibited a capacitance retention of 73.5 % during 10,000 charging-discharging cycles at a current density of 20 A·g⁻¹.