Ti3C2-Mxene-dispersion and morphology controlled battery-type nickel cobalt sulphide based nanocomposites for the application as aqueous asymmetric supercapacitor with improved rate

Nickel cobalt sulphide (NiCo₂S₄) is a promising battery-type electrode material due to its high theoretical capacitance and rich redox activity. However, its poor electrical conductivity and structural instability hinder practical application. Incorporation of two-dimensional (2D) Ti₃C₂ MXene can address these issues by improving conductivity and mechanical integrity. While previous studies have explored the synergistic effects of Ti₃C₂ and NiCo₂S₄, the influence of MXene exfoliation state and morphology control on electrochemical performance remains underexplored. Herein, we report a one-step hydrothermal synthesis of delaminated Ti₃C₂@NiCo₂S₄ (d-Ti₃C₂@NiCo₂S₄) composites with tunable morphology by varying hydrothermal time (4-48 h). Among them, the 24 h sample (d-Ti₃C₂@NiCo₂S₄-24) featuring a hexagonal layered platelet structure exhibits superior performance, delivering 161.94 mAh g^-1 (1165 F g^-1) at 1 A g^-1, with ~ 81% rate capability at 5 A g^-1 and 85% capacity retention over 20,000 cycles. It significantly outperforms both bare NiCo₂S₄-24 and the multilayer Ti₃C₂-based composite. The asymmetric device (d-Ti₃C₂@NiCo₂S₄-24//AC) delivers 19.88 Wh kg^-1 at 399.82 W kg^-1 with 86% retention after 9000 cycles, demonstrating excellent potential for practical energy storage applications.