Abstract: As an emerging member of the two-dimensional (2D) material family, V₂CT_X MXene shows great poten-tial in the application of lithium-ion capacitors (LICs) due to its unique structure and excellent electrical conductivity. However, severe nanosheets stacking and intra-layer transport barriers have limited the further development of V₂CT_X MXene-based materials. Herein, we prepared K⁺ ions and -O functional group co-modified V₂CT_X MXene (VCT-K) and further incorporated it with single-walled carbon nanotube (SWCNT), obtaining freestanding V₂CT_X composite films (VCT-K@C) with the 3D conductive network. Significantly, K⁺ ions were introduced into V₂CT_X MXene to stabilize the interlayer structure and prevent the aggregation of nanosheets, the terminal group of -O was controllably modified on the surface of MXene to improve the Li⁺ ions storage reversible capacities and the SWCNT acted as the bridge between MXene nanosheets to opens up the channels for ion/electron transportation in the longitudinal direction. Benefited from the synergistic effect of VCT-K and SWCNT, the VCT-K@C exhibits superior reversible specific capacities of 671.8 mA h g^-1 at 0.1 A g^-1 and 318 mA h g^-1 at 1.0 A g^-1. Furthermore, the assem-bled LICs with VCT-K@C anode coupling activated carbon (AC) cathode deliver an outstanding power den-sity of 19.0 kW kg^-1 at 67.4 Wh kg^-1, a high energy density of 140.5 Wh kg^-1 at 94.8 W kg^-1 and a stable capacitance retention of 86% after 6000 cycles at 10 A g^-1. Such unique structures and excellent electro-chemical properties are expected to pave the way for the large-scale application in LICs of MXene-based materials.

Key words: Interlayer and intralayer co-modification, MXene, SWCNT, Flexible self-supported anodes, Lithium-ion capacitors