An intercalated structure MXene@CCNS: cuttlefish ink-derived carbon nanospheres composite Ti3C2Tx MXene for supercapacitors

The Ti 3 C 2 T x MXene with unique two-dimensional layered structure is a promising material for energy storage. However, the self-stacking behavior of MXene nanosheets limits its electrochemical performance. In this study, a heterostructured composite has been developed by intercalating cuttlefish ink-derived carbon nanospheres into layers of Ti 3 C 2 T x MXene nanosheet through an electrostatic self-assembly method. This design effectively increases the interlayer spacing of MXene, and prevents it from tightly stacking. The heterostructure enlarges the specific surface area and exposes more active sites, thus improving the charge storage capacity and ion/electron transport. In Addition, the heterostructure buffers the volume changes of electrode material during charge-discharge processes, resulting in enhanced cycling stability. Density functional theory (DFT) calculations confirmed that the heterostructure effectively modulates the electronic structure of MXene. Compared to pure MXene, the composite exhibits significantly improved specific capacitance (264 F g −1 at 0.5 A g −1 ), better rate capability (76.9 % capacitance retention from 0.5 A g −1 to 10 A g −1 ) and greater cycling stability (93.4 % capacitance retention after 5000 cycles). Based on this electrode material, the assembled symmetric supercapacitor achieves 12.8 Wh kg −1 of energy density at 0.2 kW kg −1 of power density and a capacitance retention of 91.7 % after 5000 cycles.