Lightweight flexible Ni@wood ultrathin wood-based superhydrophobic composite film for absorption-dominated electromagnetic interference shielding and electrothermal management

Flexible multifunctional electromagnetic interference (EMI) shielding composites made from natural renewable resources are important as wireless communication technology advances. An EMI shielding layered flexible wood-based composite with insulating wood as the matrix, which is dominated by absorption and possesses Joule heating performance and superhydrophobic qualities at low voltage is difficult to construct. Electroless Ni was applied in a two-step process, followed by compression molding to prepare an electroless Ni wood-based composite film (NWF). NWF has the maximum EMI shielding effectiveness (43.4 dB) at a thickness of 70 μm. The specific electromagnetic shielding efficiency (SSE/t) of NWF in the X-band is 7848.1 dB cm² g⁻¹ . The excellent electromagnetic double loss characteristics and good impedance matching make the average absorption coefficient of the composite film reach 0.5, indicating that its absorption of electromagnetic waves is effective. The superhydrophobic electroless Ni wood-based composite film (S-NWF) was subsequently fabricated by applying a hydrophobic modifier to the surface of NWF. S-NWF has exceptional EMI shielding resilience during exposure to diverse severe circumstances, including aggressive chemical environments and high operating temperatures. In addition, the S-NWF can de-ice due to its outstanding Joule heating capability (193.8 °C at 1.25 V). A wood-based multifunctional composite material with dependable high-performance EMI shielding is proposed in this study, providing a research platform for wood-based biomass to replace non-renewable and costly electromagnetic shielding materials. • The S-NWF were successfully prepared by a simple electroless plating and spraying technics method. • The S-NWF with different gradient SE can be obtained by adjusting different electroless Ni time and substrate thickness. • The S-NWF has excellent temperature resistance, corrosion resistance and environmental stability. • The S-NWF has excellent Joule heating characteristics at low voltage. • The S-NWF has absorption-dominated electromagnetic shielding performance.