Developing excellent absorption-dominant electromagnetic interference (EMI) shielding composites is an urgent demand for the rapid development of 5 G technology and electronic equipment. Herein, a simple strategy is employed to fabricate carbon nanotubes-polypropylene fibers (CP) /polypropylene-glass fibers felt (PGFF)/Fe₃O₄ composites with superior EMI shielding effectiveness and low reflection due to the magnetic-conductive bi-gradient structure which is naturally formed by deposition during the vacuum-assisted filtration process. The difference in dimensionality between one-dimensional CNT with outstanding electrical conductivity and zero-dimensional magnetic Fe₃O₄ nanoparticles is the theoretical basis for the successful construction of the magnetic-conductive bi-gradient structure in a gap-rich PGFF matrix that endows the composites with “absorb-reflect-reabsorb” EMI shielding mechanism. When the electromagnetic waves are incident from the magnetic layer, the EMI shielding effectiveness (SE) reaches 48.9 dB as the weight percentage of the conductive layer increases, more importantly, the reflection coefficients are reduced by more than 0.32 compared with that of another incident pattern. What's more, the resultant composites exhibit an outstanding signal shielding function in the application. This work paves a convenient pathway for designing a magnetic-conductive bi-gradient structure and efficient absorbing EMI shielding composites applied in the next-generated electronic information and communication field.

开发优异的吸收型电磁干扰（EMI）屏蔽复合材料是5G技术和电子设备快速发展的迫切需求。在此，采用一种简单的策略来制造碳纳米管-聚丙烯纤维（CP）/聚丙烯-玻璃纤维毡（PGFF）/Fe ₃ O ₄复合材料，该复合材料具有优异的 EMI 屏蔽效果和由于导磁双梯度结构而具有的低反射率。它是在真空辅助过滤过程中通过沉积自然形成的。具有优异导电性的一维碳纳米管与零维磁性Fe ₃ O _{4的维数差异}纳米粒子是在富含间隙的 PGFF 基体中成功构建导磁双梯度结构的理论基础，赋予复合材料“吸收-反射-再吸收”的 EMI 屏蔽机制。当电磁波从磁性层入射时，随着导电层重量百分比的增加，EMI屏蔽效果（SE）达到48.9 dB，更重要的是，与其他入射图案相比，反射系数降低了0.32以上. 更重要的是，所得复合材料在应用中表现出出色的信号屏蔽功能。