Asymmetric phase-change composites for green electromagnetic interference shielding and efficient thermal management

With the rapid expansion of 5 G technology and high-power electronics, the development of materials that simultaneously address electromagnetic interference (EMI) and overheating remains a significant challenge. In this study, an asymmetric polyimide (PI)-based phase change composite material with two complementary functional layers is developed using an “in-situ monolithic formation” process. The top layer consists of a low-conductivity (10⁻³ to 10⁻² S/m) MXene/PI aerogel impregnated with polyethylene glycol (PEG), which serves as an impedance-matching layer for incident electromagnetic wave penetration and absorption, and as a medium for efficient latent heat storage. In contrast, the bottom layer is a high-conductivity (10 ³ S/m) MXene/PI film that reflects the penetrating electromagnetic waves and promotes in-plane heat spreading. This synergistic architecture demonstrates an outstanding EMI shielding effectiveness (SE) of 46.7 dB and an impressive absorption coefficient (A) of 0.6, realizing an absorption-dominated green EMI shielding. Furthermore, owing to the high enthalpy (191.8 J/g) of the composite phase-change material and the thermal diffusion effect of the MXene/PI film, the composite exhibits outstanding thermal management and uniform heat transfer capabilities, as confirmed by both thermal management experiments and COMSOL simulations. Its structural integrity is equally impressive, with excellent anti-leakage properties and remarkable cyclic stability. After 100 heating-cooling cycles, the material retains a high enthalpy retention rate of 99.49 %, underscoring its durability and reliability. This work not only introduces a high-performance material but also provides a promising design framework for multifunctional composites in next-generation electronic devices.