Superhigh Electromagnetic Interference Shielding of Ultrathin Aligned Pristine Graphene Nanosheets Film

Ultrathin, lightweight, high-strength, and thermally conductive electromagnetic interference (EMI) shielding materials with high shielding effectiveness (SE) are highly desired for next-generation portable and wearable electronics. Pristine graphene (PG) has a great potential to meet all the above requirements, but the poor processability of PG nanosheets hinders its applications. Here, efficient synthesis of highly aligned laminated PG films and nacre-like PG/polymer composites with a superhigh PG loading up to 90 wt% by a scanning centrifugal casting method is reported. Due to the PG-nanosheets-alignment-induced high electrical conductivity and multiple internal reflections, such films show superhigh EMI SE comparable to the reported best synthetic material, MXene films, at an ultralow thickness. An EMI SE of 93 dB is obtained for the PG film at a thickness of ≈100 µm, and 63 dB is achieved for the PG/polyimide composite film at a thickness of ≈60 µm. Furthermore, such PG-nanosheets-based films show much higher mechanical strength (up to 145 MPa) and thermal conductivity (up to 190 W m⁻¹ K⁻¹) than those of their MXene counterparts. These excellent comprehensive properties, along with ease of mass production, pave the way for practical applications of PG nanosheets in EMI shielding.     

Preparation of Porous Silver Nanowires-Melamine Formaldehyde Hybrid Composite Materials and Their Electromagnetic Shielding and Flame-Retardant Properties

Along with the booming development of communication technology and electronic equipment, higher requirements of flame-retardant and EMI shielding performances for electromagnetic interference (EMI) shielding materials are put forward. Herein, the ultralight and porous silver nanowires (AgNWs)-melamine formaldehyde (MF) hybrid composite with unique micro-/nanostructure is developed by a facile dip-coating method, which uses the AgNWs as 1D conductive coating and MF foam (MF foam) as 3D skeleton template. Benefiting from the unique porous micro-/nanostructure, the resultant hybrid composite displays low density, excellent EMI shielding performances, and superior flame-retardant property. The EMI shielding effectiveness (SE) and specific EMI SE (SSEt) of the hybrid composite in X-band (8.2–12.4 GHz) can be up to 77 dB and 26971.4 dB cm⁻² g⁻¹, respectively. At the same time, the hybrid composite also passes the vertical burning test and shows an increased LOI value of 40.6%. The combination of flame-retardant and EMI shielding performances for EMI shielding materials makes the AgNWs-MF hybrid composite great application potential in civil and military fields. This work provides a new guide for the design of multifunctional high-performance EMI shielding materials.     

Scalable Fabrication of Nacre-Structured Graphene/Polytetrafluoroethylene Films for Outstanding EMI Shielding Under Extreme Environment

In this work, inspired by the great advantage of the unique “brick-mortar” layered structure as electromagnetic interference (EMI) shielding materials, a multifunctional flexible graphene nanosheets (GNS)/polytetrafluoroethylene (PTFE) composite film with excellent EMI shielding effects, impressive Joule heating performance, and light-to-heat conversion efficiency is fabricated based on the self-emulsifying process of PTFE. Both PTFE microspheres and nanofibers are employed together for the first time as “sand and cement” to build unique nacre-structured EMI shielding materials. Such configuration can obviously enhance the adhesion of composites and improve their mechanical property for the application under extreme environment. Moreover, the simple and effective repetitive roll pressing method can be used for the scalable production in industrialization. The GNS/PTFE composite film shows a high EMI shielding effectiveness (SE) of 50.85 dB. Furthermore, it has a high thermal conductivity of 16.54 W (m K)⁻¹, good flexibility, and recyclable properties. The excellent fire-resistant and hydrophobic properties of GNS/PTFE film also ensure its reliability and safety in practical application. In conclusion, the GNS/PTFE film demonstrates the potential for industrial manufacturing, and outstanding EMI shielding performance with high stability and durability, which has a broad application prospect for electronic devices in practical extreme outdoor environments.     

Segregated poly(vinylidene fluoride)/MWCNTs composites for high-performance electromagnetic interference shielding

Conductive polymer composites (CPCs) that contain a segregated structure have attracted significant attentions because of their promising for fulfilling low filler contents with high electromagnetic interference (EMI) properties. In the present study, segregated poly(vinylidene fluoride) (PVDF)/multi-walled carbon nanotubes (MWCNTs) composites were successfully prepared by mechanical mixing and hot compaction. The PVDF/MWCNTs samples with 7 wt% filler content possess high electrical conductivities and high EMI shielding effectiveness (SE), reaching 0.06 S cm⁻¹ and 30.89 dB (in the X-band frequency region), much higher than lots of reported results for CNT-based composites. And the EMI SE greatly increased across the frequency range as the sample thickness was improved from 0.6 to 3.0 mm. The EMI shielding mechanisms were also investigated and the results demonstrated absorption dominating shielding mechanism in this segregated material. This effective preparation method is simple, low-cost, and environmentally-friendly and has potential industrial applications in the future.     

Versatile Electronic Textile Enabled by a Mixed-Dimensional Assembly Strategy

Electronic textiles (e-textiles) hold great promise for serving as next-generation wearable electronics owing to their inherent flexible, air-permeable, and lightweight characteristics. However, these e-textiles are of limited performance mainly because of lacking powerful materials combination. Herein, a versatile e-textile through a simple, high-efficiency mixed-dimensional assembly of 2D MXene nanosheets and 1D silver nanowires (AgNWs) are presented. The effective complementary actions of MXene and AgNWs endow the e-textiles with superior integrated performances including self-powered pressure sensing, ultrafast joule heating, and highly efficient electromagnetic interference (EMI) shielding. The textile-based self-powered smart sensor systems obtained through the screen-printed assembly of MXene-based supercapacitor and pressure sensor are flexible and lightweight, showing ultrahigh specific capacitance (2390 mF cm⁻²), robust areal energy density (119.5 µWh cm⁻²), excellent sensitivity (474.8 kPa⁻¹), and low detection limit (1 Pa). Furthermore, the interconnected conductive MXene/AgNWs network enables the e-textile with ultrafast temperature response (10.4 °C s⁻¹) and outstanding EMI shielding effectiveness of ≈66.4 dB. Therefore, the proposed mixed-dimensional assembly design creates a multifunctional e-textile that offers a practical paradigm for next-generation smart flexible electronics.     

Lightweight multi-walled carbon nanotube buckypaper/glass fiber–epoxy composites for strong electromagnetic interference shielding and efficient microwave absorption

Multi-walled carbon nanotube buckypaper (BP) reinforced glass fiber–epoxy (GF/EP) composites were selected to fabricate electromagnetic interference (EMI) shielding and microwave absorbing materials. Six different composite configurations with 3.0 mm thick have been conceived and tested over the X-band (8.2–12.4 GHz). Flexible and low-density (0.29 g/cm³) BP provided a high specific EMI SE of 76 dB with controlled electrical conductivity. GF/EP/BP₁₁₁ and GF/EP/BP₁₀₁ composites possess EMI SE as high as of 50–60 dB, which can be attributed to the number of BP inserted and variation in the wave-transmitting layer of the laminates. Furthermore, the shielding mechanism was discussed and suggested that the absorption was the dominant contribution to EMI SE. GF/EP/BP₁₁₀ laminate demonstrated suitable EMI performance (~?20 dB), whereas GF/EP/BP₀₁₁ composite revealed excellent microwave performance, achieving an effective ? 10 dB bandwidth of 3.04 GHz and minimum reflection loss (RL) value of ? 21.16 dB at 10.37 GHz. On the basis of these results, GF/EP/BP composites prepared in this work have potential applications as both EMI shielding and microwave absorber materials given their facile preparation and lightweight use.

     

Dough-Like Aramid Nanofiber Putty-Assisted Design of Free-Standing Liquid Metal-Based Films for Ultrahigh Electromagnetic Interference Shielding

Gallium-based liquid metal (LM) is expected to be an ideal candidate for flexible electromagnetic interference (EMI) shielding materials in wearable electronics due to its excellent electrical conductivity and extraordinary fluidity. However, it is difficult to fabricate LM as a free-standing material due to its high surface tension and unmanageable fluidity, as well as its poor compatibility with other materials. Herein, a processing strategy is developed to fabricate free-standing LM-based films by vacuum filtration with the assistance of dough-like aramid nanofiber (ANF) putty. The ANF putty improves the compatibility of ANF and LM, and also greatly improves the stability, reliability, and processability of ANF. Rational design of the structure enables the preparation of LM/ANF films with ANF as the nanobridge connecting LM micro/nanodroplets, and ANF-LM-ANF sandwich films with ANF as the shells, LM layer as the core. The LM/ANF film (tensile strength: 5.4 MPa) exhibits an ultrahigh EMI SE of up to 105.9 dB (8.0–12.4 GHz) at a thickness of 60 μm. While the ANF-LM-ANF sandwich film has higher mechanical strength (33.1 MPa), and also has good EMI shielding properties. The average EMI SE of the 10 μm thick sandwich film exceeds 45 dB in the X-band.     

Anticorrosive,Ultralight, and Flexible Carbon‐Wrapped Metallic Nanowire Hybrid Sponges for Highly Efficient Electromagnetic Interference Shielding

Metal‐based materials with exceptional intrinsic conductivity own excellent electromagnetic interference (EMI) shielding performance. However, high density, corrosion susceptibility, and poor flexibility of the metal severely restrict their further applications in the areas of aircraft/aerospace, portable and wearable smart electronics. Herein, a lightweight, flexible, and anticorrosive silver nanowire wrapped carbon hybrid sponge (Ag@C) is fabricated and employed as ultrahigh efficiency EMI shielding material. The interconnected Ag@C hybrid sponges provide an effective way for electron transport, leading to a remarkable conductivity of 363.1 S m^?1 and superb EMI shielding effectiveness of around 70.1 dB in the frequency range of 8.2–18 GHz, while the density is as low as 0.00382 g cm^?3, which are among the best performances for electrically conductive sponges/aerogels/foams by far. More importantly, the Ag@C sponge surprisingly exhibits super‐hydrophobicity and strong corrosion resistance. In addition, the hybrid sponges possess excellent mechanical resilience even with a large strain (90% reversible compressibility) and an outstanding cycling stability, which is far better than the bare metallic aerogels, such as silver nanowire aerogels and copper nanowire foams. This strategy provides a facile methodology to fabricate lightweight, flexible, and anticorrosive metal‐based sponge for highly efficient EMI shielding applications.     

Multifunctional Nanocrystalline-Assembled Porous Hierarchical Material and Device for Integrating Microwave Absorption,Electromagnetic Interference Shielding,and Energy Storage

Multifunctional applications including efficient microwave absorption and electromagnetic interference (EMI) shielding as well as excellent Li-ion storage are rarely achieved in a single material. Herein, a multifunctional nanocrystalline-assembled porous hierarchical NiO@NiFe₂O₄/reduced graphene oxide (rGO) heterostructure integrating microwave absorption, EMI shielding, and Li-ion storage functions is fabricated and tailored to develop high-performance energy conversion and storage devices. Owing to its structural and compositional advantages, the optimized NiO@NiFe₂O₄/15rGO achieves a minimum reflection loss of −55 dB with a matching thickness of 2.3 mm, and the effective absorption bandwidth is up to 6.4 GHz. The EMI shielding effectiveness reaches 8.69 dB. NiO@NiFe₂O₄/15rGO exhibits a high initial discharge specific capacity of 1813.92 mAh g⁻¹, which reaches 1218.6 mAh g⁻¹ after 289 cycles and remains at 784.32 mAh g⁻¹ after 500 cycles at 0.1 A g⁻¹. In addition, NiO@NiFe₂O₄/15rGO demonstrates a long cycling stability at high current densities. This study provides an insight into the design of advanced multifunctional materials and devices and provides an innovative method of solving current environmental and energy problems.     

Ultrahigh Conductive Copper/Large Flake Size Graphene Heterostructure Thin‐Film with Remarkable Electromagnetic Interference Shielding Effectiveness

To guarantee the normal operation of next generation portable electronics and wearable devices, together with avoiding electromagnetic wave pollution, it is urgent to find a material possessing flexibility, ultrahigh conductive, and superb electromagnetic interference shielding effectiveness (EMI SE) simultaneously. In this work, inspired by a building bricks toy with the interlock system, we design and fabricate a copper/large flake size graphene (Cu/LG) composite thin film (≈8.8 μm) in the light of high temperature annealing of a large flake size graphene oxide film followed by magnetron sputtering of copper. The obtained Cu/LG thin‐film shows ultrahigh thermal conductivity of over 1932.73 (±63.07) W m^?1 K^?1 and excellent electrical conductivity of 5.88 (±0.29) × 10⁶ S m^?1. Significantly, it also exhibits a remarkably high EMI SE of over 52 dB at the frequency of 1–18 GHz. The largest EMI SE value of 63.29 dB, accorded at 1 GHz, is enough to obstruct and absorb 99.99995% of incident radiation. To the best of knowledge, this is the highest EMI SE performance reported so far in such thin thickness of graphene‐based materials. These outstanding properties make Cu/LG film a promising alternative building block for power electronics, microprocessors, and flexible electronics.     

Influence of aspect ratio and skin effect on EMI shielding of coating materials fabricated with carbon nanofiber/PVDF

The effectiveness of electromagnetic interference (EMI) shielding was measured for poly vinylidene fluoride (PVDF) coating materials containing carbon nanofibers. Carbon nanofibers produced from the C₂H₄/NC73 system exhibited higher shielding effectiveness (SE) by relatively large specific surface area and high aspect ratio than those from others. When the thickness of carbon nanofibers filled PVDF coating materials varied from 25 to 50 m, the electrical conductivity of coating materials increased sharply from 1.34 to 1.91 S/cm. However, the electrical conductivity approached a certain value with further raise of the thickness. This phenomenon denotes that a critical thickness of coating materials exists around 50 m. The electrical conductivity and SE of coating materials decreased dramatically as the carbon nanofiber fillers were milled. It could be concluded that the decrease of the shielding effectiveness of carbon nanofiber filled composite was due to the decrease of the filler's aspect ratio by ball milling.     

Electromagnetic Shielding of Monolayer MXene Assemblies

Miniaturization of electronics demands electromagnetic interference (EMI) shielding of nanoscale dimension. The authors report a systematic exploration of EMI shielding behavior of 2D Ti₃C₂T_x MXene assembled films over a broad range of film thicknesses, monolayer by monolayer. Theoretical models are used to explain the shielding mechanism below skin depth, where multiple reflection becomes significant, along with the surface reflection and bulk absorption of electromagnetic radiation. While a monolayer assembled film offers ≈20% shielding of electromagnetic waves, a 24-layer film of ≈55 nm thickness demonstrates 99% shielding (20 dB), revealing an extraordinarily large absolute shielding effectiveness (3.89 × 10⁶ dB cm² g⁻¹). This remarkable performance of nanometer-thin solution processable MXene proposes a paradigm shift in shielding of lightweight, portable, and compact next-generation electronic devices.     

A mechanistic study on electromagnetic shielding effectiveness of polysulfone/carbon nanofibers nanocomposites

The present study aims to produce a light weight electromagnetic interference (EMI) shielding material from carbon nanofibers (CNFs)-based polysulfone (PSU) nanocomposites. EMI shielding effectiveness (EMI SE) was studied by analyzing the electromagnetic wave transmission, reflection, and absorption characteristics of nanocomposites. The electrical conductivity and EMI SE of the nanocomposite with different weight percentage of CNFs (3–10 wt%) were investigated at room temperature and the measurement of EMI SE was carried out in a frequency range of 8.2–12.4 GHz (X-band). The mechanism of EMI shielding of PSU/CNFs nanocomposite has been well explained by comparing the contribution of reflection and absorption to the total EMI SE. The state of dispersion of CNFs and PSU–CNFs interaction was studied by high resolution transmission electron microscopy and scanning electron microscopy. The thermal stability of nanocomposite studied from thermogravimetric analysis was increased after addition of CNFs to PSU matrix. Electrical conductivity of nanocomposite followed power law model of percolation theory having a percolation threshold Φ_c = 0.0079 vol% (0.9 wt%) and exponent t = 1.73. The EMI SE of nanocomposites with thickness of 1 mm was 19–45 decibel (dB) at 3–10 wt% CNFs loading. This high thermal stability and high EMI SE suggest the potential use of PSU/CNFs nanocomposite as effective lightweight EMI shielding material in different electronic applications.     

Hierarchical,seamless, edge-rich nanocarbon hybrid foams for highly efficient electromagnetic-interference shielding

Lightweight,flexible,ultrahigh-performance electromagnetic-interference (EMI) shielding materials are urgently required in the areas of aircraft/aerospace,portable and wearable electronics.Herein,1D carbon nanotubes (CNT) and carbon nanofibers (CNF) with 2D edge-rich graphene (ERG) are used to form a lightweight,flexible CNT-ERG-CNF hybrid foam.This foam was fabricated through a self-sacrificial templating chemical vapor deposition process,where nanocarbons bond through covalent bonding,forming a hierarchical 3D hybridized carbon nanostructure.Multistage conductive networks and heterogeneous interfaces were constructed using edge-rich nanocarbons to increase the induced currents and interracial polarization which makes great contributions to achieve high absorption electromagnetic shielding effectiveness (SEA).The CNT-ERG-CNF hybrid foam exhibits EMI shielding effectiveness (SE) exceeding 55.4 dB in the X-band while the specific SE (SSE,SE divided by mass density) achieves 9200 dB cm3 g-1,which surpasses that of nearly all other carbon-based composite materials.Furthermore,the structural stability and durability of the flexible CNT-ERG-CNF hybrid foams is examined by measuring EMI SE after 10000 times cyclic bending.Remarkably,this work not only provides a new idea for preparing hierarchical carbon materials for a wide range of applications,but presents some fundamental insights for achieving higher absorption losses in EMI shielding materials.     

Microstructure Design of Lightweight,Flexible, and High Electromagnetic Shielding Porous Multiwalled Carbon Nanotube/Polymer Composites

Multiwalled carbon nanotube/polymer composites with aligned and isotropic micropores are constructed by a facile ice‐templated freeze‐drying method in a wide density range, with controllable types and contents of the nanoscale building blocks, in order to tune the shielding performance together with the considerable mechanical and electrical properties. Under the mutual promotion of the frame and porous structure, the lightweight high‐performance shielding is achieved: a 2.3 mm thick sample can reach 46.7 and 21.7 dB in the microwave X‐band while the density is merely 32.3 and 9.0 mg cm^?3, respectively. The lowest density corresponds to a value of shielding effectiveness divided by both the density and thickness up to 10⁴ dB cm² g^?1, far beyond the conductive polymer composites with other fillers ever reported. The shielding mechanism of the flexible porous materials is further demonstrated by an in situ compression experiment.     

Carbon Nanotube–Multilayered Graphene Edge Plane Core–Shell Hybrid Foams for Ultrahigh‐Performance Electromagnetic‐Interference Shielding

Materials with an ultralow density and ultrahigh electromagnetic‐interference (EMI)‐shielding performance are highly desirable in fields of aerospace, portable electronics, and so on. Theoretical work predicts that 3D carbon nanotube (CNT)/graphene hybrids are one of the most promising lightweight EMI shielding materials, owing to their unique nanostructures and extraordinary electronic properties. Herein, for the first time, a lightweight, flexible, and conductive CNT–multilayered graphene edge plane (MLGEP) core–shell hybrid foam is fabricated using chemical vapor deposition. MLGEPs are seamlessly grown on the CNTs, and the hybrid foam exhibits excellent EMI shielding effectiveness which exceeds 38.4 or 47.5 dB in X‐band at 1.6 mm, while the density is merely 0.0058 or 0.0089 g cm^?3, respectively, which far surpasses the best values of reported carbon‐based composite materials. The grafted MLGEPs on CNTs can obviously enhance the penetration losses of microwaves in foams, leading to a greatly improved EMI shielding performance. In addition, the CNT–MLGEP hybrids also exhibit a great potential as nano‐reinforcements for fabricating high‐strength polymer‐based composites. The results provide an alternative approach to fully explore the potentials of CNT and graphene, for developing advanced multifunctional materials.     

Ultrathin,flexible,and high-strength Ni/Cu/metallic glass/Cu/Ni composite with alternate magneto-electric structures for electromagnetic shielding

Electromagnetic interference (EMI) shielding materials with ultrathin,flexible,superior mechanical and thermal management properties are highly desirable for smart and wearable electronics.Here,ultrathin and flexible Ni/Cu/metallic glass/Cu/Ni (Ni/Cu/MG) multilayer composite with alternate magnetic and electrical structures was designed via facial electroless plating of Cu and Ni on an Fe-based metallic glass.The resultant 0.02 mm-thick Ni/Cu/MG composite displays a superior EMI shielding effectiveness (EMISE)of 35 dB and a great EMISE/t of 1750 dB/mm,which is greater than those of composites with monotonous multilayer or homogeneous structures.The improved EMI SE originates from the massive ohmic losses,the enhanced internal reflection/absorption,and the abundant interfacial polarization loss.Particularly,Ni/Cu/MG exhibits a high tensile strength of up to 1.2 GPa and outstanding mechanical stability,enabling the EMI SE remains unchanged after 10,000 times of bending.Moreover,Ni/Cu/MG has excellent Joule heating characteristics and thermal stability,which is very suitable for heating components of wearable hyperthermia devices.     

Superior mechanical and electrical properties of multiwall carbon nanotube reinforced acrylonitrile butadiene styrene high performance composites

In-house synthesized multiwall carbon nanotubes (MWCNTs) have been dispersed in acrylonitrile butadiene styrene (ABS) using a micro twin-screw extruder with back flow channel. The electrical and mechanical properties of MWCNTs in ABS with different wt% have been studied. Incorporation of only 3 wt. % MWCNTs in ABS leads to significant enhancement in the tensile strength (up to 69.4 MPa) which was equivalent to 29% increase over pure ABS. The effect of MWCNTs on the structural behaviour of ABS under tensile loading showed a ductile to brittle transition with increase concentration of MWCNTs. The results of enhanced mechanical properties were well supported by micro Raman spectroscopic and scanning electron microscopic studies. In addition to the mechanical properties, electrical conductivity of these composites increased from 10⁻¹² to 10⁻⁵ Scm⁻¹ showing an improvement of ∼7 orders of magnitude. Due to significant improvement in the electrical conductivity, EMI shielding effectiveness of the composites is achieved up to −39 dB for 10 wt. % loaded MWCNTs/ABS indicating the usefulness of this material for EMI shielding in the Ku-band. The mechanism of improvement in EMI shielding effectiveness is discussed by resolving their contribution in absorption and reflection loss. This material can be used as high-strength EMI shielding material.     

可用于包装的纤维素基电磁屏蔽材料研究进展

目的 为推动可用于包装的纤维素基电磁干扰(Electromagnetic Interference,EMI)屏蔽材料更深入的研究,综述一些具有包装材料潜质和EMI屏蔽功能的纤维素基薄膜、织物和气凝胶的最新研究进展。方法 主要介绍纤维素基薄膜、织物和气凝胶等3类EMI屏蔽材料的制备方法、EMI屏蔽性能、多功能性和在包装上应用的潜力。结果 当下纤维素基EMI屏蔽材料表现出令人满意的EMI屏蔽效能(EMI Shielding Effectiveness, EMI SE)和力学性能,有望作为包装材料。同时一些材料还显示出抗菌、隔热、抗冲击等特性,使得这些材料能在复杂的场景下应用。结论 通过合理的设计,纤维素基EMI屏蔽材料可拥有优异的EMI屏蔽性能、出色的力学性能和良好的耐用性。归因于上述优势和绿色可降解的特性,这类材料有望在未来取代传统的EMI屏蔽包装材料,然而这些材料通常需要精细的制备工艺,材料的量产和实际应用依然是亟待解决的问题。     

Electromagnetic interference (EMI) shielding of single-walled carbon nanotube epoxy composites

Single-walled carbon nanotube (SWNT)-polymer composites have been fabricated to evaluate the electromagnetic interference (EMI) shielding effectiveness (SE) of SWNTs. Our results indicate that SWNTs can be used as effective lightweight EMI shielding materials. Composites with greater than 20 dB shielding efficiency were obtained easily. EMI SE was tested in the frequency range of 10 MHz to 1.5 GHz, and the highest EMI shielding efficiency (SE) was obtained for 15 wt % SWNT, reaching 49 dB at 10 MHz and exhibiting 15-20 dB in the 500 MHz to 1.5 GHz range. The EMI SE was found to correlate with the dc conductivity, and this frequency range is found to be dominated by reflection. The effects of SWNT wall defects and aspect ratio on the EMI SE were also studied.