Multifunctional CoFe₂O₄@MXene-AgNWs/Cellulose Nanofiber Composite Films with Asymmetric Layered Architecture for High-Efficiency Electromagnetic Interference Shielding and Remarkable Thermal Management Capability

Abstract

Developing high-efficiency electromagnetic interference (EMI) shielding composite films with outstanding flexibility and excellent thermal management capability is vital but challenging for modern integrated electronic devices. Herein, a facile two-step vacuum filtration method was used to fabricate ultrathin, flexible, and multifunctional cellulose nanofiber (CNF)based composite films with an asymmetric layered architecture. The asymmetric layered structure is composed of a lowconductivity CoFe 2 O 4 @MXene/CNF layer and a highly conductive silver nanowires (AgNWs)/CNF layer. Benefiting from the rational placement of the impedance matching layer and shielding layer, as well as the synergistic effect of electric and magnetic losses, the resultant composite film exhibits an extremely high EMI shielding effectiveness (SE) of 73.3 dB and an average EMI SE of 70.9 dB with low reflected efficiency of 4.9 dB at only 0.1 mm thickness. Sufficiently reliable EMI SE (over 95% reservation) is attained even after suffering from continuous physical deformations and long-term chemical attacks. Moreover, the prepared films exhibit extraordinary flexibility, strong mechanical properties, and satisfactory thermal management capability. This work offers a viable strategy for exploiting high performance EMI shielding films with attractive thermal management capacity, and the resultant films present extensive application potential in aerospace, artificial intelligence, advanced electronics, stealth technology, and the national defense industry, even under harsh environments.

Design and Fabrication of Layered Electromagnetic Interference Shielding Materials: A Cost-Effective Strategy for Performance Prediction and Efficiency Tuning

“…Apart from polarization losses, EM waves will attenuate due to magnetic losses as well . In any ferrite-containing composites, the magnetic losses are contributed mainly by three factors, viz., eddy current, hysteresis, and resonance. , However, in the case of hexaferrites, eddy current loss and hysteresis loss play major roles in energy attenuation as resonance relaxation of hexaferrites usually occurs beyond 40 GHz . Both the eddy current loss and hysteresis loss lead to the conversion of EM energy into heat energy, which eventually dissipates throughout the material.…”

“…Electromagnetic interference shielding materials can be broadly classified into two types; reflection-dominated and absorption-dominated shielding materials based on the two primary mechanisms involved in EMI shielding, which are reflection and absorption. Even though high EMI shielding effectiveness (SE) can be achieved by metals, conductive polymers, and from conductive low-dimensional materials such as reduced graphene oxide and MXenes, the inevitable reflection of EM waves associated with the conductivity of a material may bring negative impacts to the environment and precision electronic devices confined to a small area used in aerospace and military applications. ,− Thus, it is essential to tune material combinations so that the shielding effectiveness due to absorption (SE A ) dominates over the shielding effectiveness due to reflection (SE R ). Such material combinations can be achieved by suitably incorporating magnetic and conducting materials so as to promote impedance matching and thereby reduce the reflection of EM waves. ,− Further, reports indicate that multilayered arrangement of magnetic and conductive structures is an efficient way to integrate the shielding performance of composites by exploiting the mechanism of multiple internal reflections arising from the impedance mismatch of the heterogeneous layers. , …”

MOF-Derived Co/C and MXene co-Decorated Cellulose-Derived Hybrid Carbon Aerogel with a Multi-Interface Architecture toward Absorption-Dominated Ultra-Efficient Electromagnetic Interference Shielding

“…MXene was successfully synthesized, according to our previous research studies. ,, ZIF-67 was fabricated through a simple precipitation method at room temperature. Briefly, 0.291 g of Co­(NO 3 ) 2 ·6H 2 O (1 mM) and 0.328 g of 2-methylimidazole (4 mM) were dissolved in 25 mL of methanol under ultrasound for 20 min, respectively.…”

Multilayer Ultrathin MXene@AgNW@MoS2 Composite Film for High-Efficiency Electromagnetic Shielding

“…Metal carbon/nitride materials (MXenes) with two-dimensional (2D) layered structures have joined the ranks of new electromagnetic shielding materials owing to their good electrical conductivity, large specific surface area, and metal-like properties. − Since 2016, 2D Ti 3 C 2 T x with tunable surface chemistry has driven the research on MXene for excellent EMI shielding. − To further enhance the inherent electromagnetic shielding properties of MXene, layering or combining with different conductive materials is used to realize a synergistic shielding effect. , For example, a 47 μm thick nanocomposite with 80 wt % Ti 3 C 2 T x exhibited 25.8 dB EMI shielding effectiveness (SE) at 12.4 GHz . The composite with a Ti 3 C 2 T x to PEDOT:PSS ratio of 7:1 depicted a relatively high EMI SE of 42.10 dB .…”