Flexible MXene/SWCNT Composite Films with Honeycomb Structure for Efficient Electromagnetic Interference Shielding and Joule Heating

The increasing trend towards miniaturization and portability in electronic devices spurs the development of lightweight, efficient, and flexible materials for electromagnetic interference (EMI) shielding. MXene (Ti 3 C 2 T x ) is an ideal EMI shielding material due to its high conductivity and two-dimensional structure, but it tends to stack easily, which limits its EMI shielding effectiveness (SE). Herein, we prepared a structurally adjustable composite film using a simple and environmentally friendly roller infiltration combined with freeze-drying method. A continuous single-walled carbon nanotube (SWCNT) film was introduced as the conductive skeleton, and freeze-drying was employed to regulate the internal structure of the composite film, which effectively mitigated the self-stacking of MXene. The limited load-bearing capacity of SWCNT film and the increase in MXene concentration jointly modulated the internal structure of the composite film changed from “large pores sparsity” to “small pores density”. Interestingly, compared to the dense film formed by vacuum drying (59 dB, 2.08 × 10 4 dB·cm 2 ·g -1 ), the film prepared by freeze-drying exhibited a honeycomb-like porous structure. When the porosity of the prepared composite film was about 59.2%, the film achieved a significant EMI SE of up to 90 dB and a specific SE of 4.63 × 10 4 dB·cm 2 ·g -1 . It also demonstrated excellent flexibility and good thermal management performance, with the surface temperature reaching 66.1°C at a voltage of 3 V, showing significant potential in aerospace and wearable electronic applications.