Impedance Matching‐Guided Multilayer Engineering in Magnetic MXene Composites for Ultra‐Broadband Electromagnetic Wave Absorption

ABSTRACT The high‐performance electromagnetic wave (EMW) absorbing materials face a fundamental challenge: traditional homogeneous absorbers struggle to achieve both broad bandwidth and strong absorption due to the limitations imposed by the Kramers–Kronig relations. To overcome this constraint, an impedance matching‐guided multilayer engineering strategy is proposed to spatially decouple this trade‐off via electromagnetic gradient architectures enabling ultra‐broadband EMW absorption. To verify this strategy, magnetic Ni@MXene absorbents with tuneable electromagnetic ratios were synthesized via electrostatic self‐assembly and in situ reduction, followed by shear‐induced alignment to construct homogeneous laminated composites. While the single laminated composites deliver strong absorption (minimum reflection loss, RL min of −62.21 dB) yet limited effective absorption bandwidth (EAB, 3.68 GHz). By assembling the laminated composites into the electromagnetic gradient multi‐layered composite with optimized stacking sequence and layer thickness based on our impedance matching‐guided multilayer engineering, a three‐layer structure composite (G3) achieves an ultra‐broad EAB of 10.4 GHz and a RL min of −60.12 dB. This exceptional performance stems from synergistic impedance matching for wave penetration and cascade dissipation across the thickness direction. This work provides a design framework for broadband high‐efficiency EMW absorbing materials with implications for next generation of electromagnetic stealth technology.