MXene/FeSiAl Composite Foam with Absorption-Dominant EMI Shielding via High Permeability of FeSiAl

Abstract The rapid development of high-frequency electronic devices urgently requires electromagnetic interference (EMI) shielding materials with both high shielding effectiveness (SE) and low reflectivity. However, achieving simultaneous high shielding and low reflectivity remains a significant challenge due to the inherent impedance mismatch. Herein, an asymmetric MXene/Flaky FeSiAl (FFSA)/expandable polymer microsphere (EPM) composite foam integrating metal soft magnetic material was constructed. Due to the particularly high permeability and low loss of FFSA, it can serve as an impedance-matching layer, allowing electromagnetic waves to enter the material with minimal surface reflection. Consequently, the composite foam delivers an EMI SE of 34.6 dB and a reflection coefficient as low as 0.03, maintaining broadband shielding above 31.9 dB across 5–27 GHz. Furthermore, the foam exhibits a near-field SE of approximately –40 dB in the 1–6 GHz band and effectively blocks wireless power transmission. This study provides a feasible strategy for developing low-reflection EMI shielding materials.