Constructing low-reflection Ni@C/CNT/PIA//CF composite fiber membrane with “absorption–reflection–reabsorption” tuned EMI shielding performance

Low-reflection electromagnetic interference (EMI) shielding materials can effectively avoid secondary pollution of electromagnetic waves through high absorption rates. However, a single structural design of EMI shielding materials is difficult to simultaneously achieve low reflectivity and high shielding efficiency. Here, a synthetic Ni@C/carbon nanotube (CNT)/polyimide (PI) porous aerogel is built and utilized as the electromagnetic wave absorption layer and a highly conductive carbon fiber (CF) fabric serves as the bottom reflective layer. Through a clever two-layer coupling design, the Ni@C/CNT/PIA//CF composite achieves the efficient shielding mechanism of “absorption–reflection–reabsorption”. In the X-band, the electromagnetic wave absorption coefficient is 0.89, and the total shielding efficiency (SE_T) reaches 50.5 dB, the excellent EMI shielding performance is attributed to the coupling structure optimizing impedance matching, extending electromagnetic wave propagation paths, and enhancing multiple scattering and interface polarization. Moreover, based on the compressive elastic recovery property of the PI matrix, the dielectric property of Ni@C/CNT, the photothermal storage property of CF, combined with the special structure design and thermal stability of the overall composite, Ni@C/CNT/PIA//CF also exhibits ideal force-resistance sensing, photothermal conversion, and flame-retardant properties. This work offers a promising strategy for next-gen EMI shielding materials with balanced high absorption, low reflection, and integrated functions.