Lightweight and compressible composite foams consisting of silver fractal dendrites (AgFDs), carbon nanotubes (CNTs) and thermoplastic polyurethane (TPU) are developed through layer-by-layer construction, followed by freeze-drying. The construction of AgFD/TPU layers through depositing AgFD layers followed by low-temperature sintering and incorporating of TPU endows the AgFD/TPU layers with excellent electrical conductivity. Meanwhile, the electrically conductive gradient CNT/TPU layers constructed by layer-by-layer method greatly decrease the reflection of the electromagnetic (EM) waves and prolong the EM wave dissipation paths. The unique low reflection–absorption-high reflection-reabsorption paths of the EM wave dissipation mechanism facilitates the composite foams with thickness of 3.4 mm to obtain an excellent EMI SE of 88.5 dB and an ultra-low SE_R of 0.29 dB at an extreme low AgFD loading of 0.103 vol%. Additionally, benefitting from direction freezing, the composite foams exhibit good cyclic compression recovery. This work puts forward a new insight for designing and constructing ultra-efficient absorption-dominated EMI shielding materials with electrically conductive gradient layers, and the prepared shielding materials are highly promising for applications in the EMI protection of modern electronic products.

由分形的银分形物（AgFDs），碳纳米管（CNTs）和热塑性聚氨酯（TPU）组成的轻质可压缩复合泡沫是通过逐层构建，然后进行冷冻干燥而开发的。通过沉积AgFD层，然后进行低温烧结和掺入TPU来构造AgFD / TPU层，使AgFD / TPU层具有出色的导电性。同时，通过逐层方法构造的导电梯度CNT / TPU层极大地减少了电磁波的反射并延长了电磁波的耗散路径。电磁波消散机制的独特的低反射-吸收-高反射-重吸收路径可促进厚度为3.4 mm的复合泡沫材料的EMI SE达到88。在0.103 vol％的极低AgFD负载下，_R为0.29 dB。另外，得益于方向冻结，复合泡沫显示出良好的循环压缩回复率。这项工作为设计和构造具有导电梯度层的超高效吸收为主的EMI屏蔽材料提出了新的见解，并且所制备的屏蔽材料在现代电子产品的EMI保护中具有广阔的应用前景。