High Electromagnetic Shielding Research Articles

Modulating Electrochemical Energy Storage and Multi-Spectra Defense of MXenes by Interfacial Dual-Filler Engineering.

MXenes have attracted growing interest in electrochemical energy storage owing to their high electronic conductivity and editable surface chemistry. Besides, rendering MXenes with spectrum defense properties further broadens their versatile applications. However, the development of MXenes suffers from weak van der Waal interaction-driven self-restacking that leads to random alignment and inferior interface microenvironments. Herein, a nacre-inspired MXene film is tailored by dual-filling of 2-ureido-4[1H]-pyrimidinone (UPy)-modified polyvinyl alcohol (PVA-UPy) and carbon nanotubes (CNTs). The dual-nanofillers engineering endows the nanocomposite film with a highly ordered structure (a Herman's order value of 0.838), a high mechanical strength (139.5MPa), and continuous conductive pathways of both the ab plane and c-axis. As a proof-of-concept, the tailored nanocomposite film achieves a considerable capacitance of 508.2 F cm-3 and long-term cycling stability without performance degradation for 10000 cycles. It is efficient for spectra defense in radar and infrared bands, displaying a high electromagnetic shielding capacity (19186dB cm2 g-1) and a super-low infrared (IR) emissivity (0.16), with negligible performance decay after saving in the air for 1 year, responsible for the applications in specific and complex conditions. This interfacial dual-filler engineering concept showcases effective nanotechnology toward sustainable energy applications with a long lifetime and safety.

Liquid Metal Grid Patterned Thin Film Devices Toward Absorption-Dominant and Strain-Tunable Electromagnetic Interference Shielding

Multiple internal reflection-based absorption-dominant stretchable electromagnetic shielding thin film by incorporating liquid metal grid structure is developed.The device demonstrates high electromagnetic shielding effectiveness (SE) (SET of up to 75 dB) with low reflectance (SER of 1.5 dB at the resonant frequency).The shielding properties of the device can be tuned by adjusting the liquid metal patterned grid spaces upon strain.

Cellulose–derived carbon scaffolds with bidirectional gradient Fe3O4 distribution: Integration of green EMI shielding and thermal management

Cellulose papers (CPs) possess a pore structure, rendering them ideal precursors for carbon scaffolds because of their renewability. However, achieving a tradeoff between high electromagnetic shielding effectiveness and low reflection coefficient poses a tremendous challenge for CP-based carbon scaffolds. To meet the challenge, leveraging the synergistic effect of gravity and evaporation dynamics, laminar CP-based carbon scaffolds with a bidirectional gradient distribution of Fe3O4 nanoparticles were fabricated via immersion, drying, and carbonization processes. The resulting carbon scaffold, owing to the bidirectional gradient structure of magnetic nanoparticles and unique laminar arrangement, exhibited excellent in-plane electrical conductivity (96.3 S/m), superior electromagnetic shielding efficiency (1805.9 dB/cm2 g), low reflection coefficients (0.23), and a high green index (gs, 3.38), suggesting its green shielding capabilities. Furthermore, the laminar structure conferred upon the resultant carbon scaffold a surprisingly anisotropic thermal conductivity, with an in-plane thermal conductivity of 1.73 W/m K compared to a through-plane value of only 0.07 W/m K, confirming the integration of thermal insulation and thermal management functionalities. These green electromagnetic interference shielding materials, coupled with thermal insulation and thermal management properties, hold promising prospects for applications in sensitive devices.

Multifunctional wood-derived cellulose/Ti3C2Tx composite films enhanced by densification strategy for electromagnetic shielding, Joule/solar heating, and thermal camouflage

In the era of increasing reliance on electronic devices, the development of flexible smart composite films that offer multifunctional capabilities such as electromagnetic shielding, sensing, infrared stealth, and autonomous heating is becoming increasingly significant. In this study, we fabricated polydopamine-modified cellulose scaffold/MXene composite films (PCM) using a densification strategy, resulting in films with a thickness of only 33 μm, outstanding tensile strength of 235.28 MPa, and excellent electromagnetic shielding effectiveness of 44.6 dB. The PCM also demonstrates remarkable electrothermal performance, reaching temperatures of up to 610 °C at 5 V, and exhibits excellent photo-thermal conversion performance, along with good cycling stability and tunability. Additionally, the PCM’s low infrared emissivity provides it with exceptional infrared stealth capabilities, effectively concealing a high surface temperature ranging from 250 °C to 25 °C. The PCM’s ability to detect human body movement and light-driven actuation for bionic motions underscores its flexibility and utility as a sensor. Therefore, this efficient and versatile approach provides a promising method for synthesizing multifunctional MXene-based composite films, achieving satisfactory mechanical properties, high electromagnetic interference shielding, and effective thermal management for wearable smart devices and military applications.

Two birds with one stone: A “needle-like” structure constructed on multifunctional PET fabric surface for flame retardancy and electromagnetic interference shielding

Here, a facile method is reported to prepare multifunctional PET fabrics with high flame retardancy, hydrophobicity and ideal electromagnetic shielding. PET fabric was firstly modified via polydopamine with mussel-like structure, and then DOPO@ZnO was constructed. A new type of composite PET fabric was prepared by simple, low-cost electroless Ni process and surface PDMS treatment (PpDPNP). The resulting composite fabric was extensively investigated for its stability and applicability in a complicated environment. The conductive interconnection network of modified fabric made it have excellent electrical conductivity and mechanical properties. Even after solution corrosion and washing, the prepared composite fabric could maintain a relatively stable electrical conductivity. The conductivity, tensile and elongation at break of composite fabric were 144.62 S/cm, 78.48 MPa and 167.49 %, respectively. The average electromagnetic interference shielding effectiveness (EMI SE) of PpDPNP reached 58.83 dB with 0.18 mm thickness and electroless Ni only 20 min at X-band, which was mainly due to large dielectric loss and multiple reflections. The modified PET fabric had self-extinguishing performance, and peak heat release rate (PHRR) and total heat release rate (THR) were 60.7 % and 59.8 % lower than pure PET fabric, respectively, indicating that the composite fabric had excellent flame retardancy.

Ultralight Flexible Collagen Fiber Based Aerogels Derived from Leather Solid Waste for High Electromagnetic Interference Shielding.

Designing and developing high-performance shielding materials against electromagnetic interference is of utmost importance due to the rapid advancement of wireless telecommunication technologies. Such materials hold both fundamental and technological significance. A three-stage process is presented for creating ultralight, flexible aerogels from biomass to shield against electromagnetic interference. Collagen fibers sourced from leather solid waste are used for: (i) freeze-drying preparation of collagen fibers/poly(vinyl alcohol) (PVA) aerogels, (ii) adsorption of silver nanowires (AgNWs) onto collagen fiber/PVA aerogels, and (iii) Hydrophobic modification of collagen fiber/PVA/AgNWs aerogels with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (POTS). Scanning electron microscopy studies reveal that an interweaving of AgNWs and collagen fiber/PVA porous network has formed a conductive network, exhibiting an electrical conductivity of 103 S·m-1. The electromagnetic interference shielding effectiveness reached more than 62 dB, while the density was merely 5.8 mg/cm3. The collagen fiber/PVA/AgNWs/POTS aerogel displayed an even better electromagnetic shielding efficiency of 73 dB and water contact angle of 147°. The study results emphasize the distinctive capacity of leather solid waste to generate cost-effective, ecofriendly, and highly efficient electromagnetic interference shielding materials.

Enhancing thermal conductivity and electromagnetic shielding performance of Ni-CNT/Al2O3/PVDF composite film with a multi-layered structure

To develop thermal interface materials with both high thermal conductivity and electromagnetic interference shielding, the polyvinylidene fluoride (PVDF) composite film was prepared by electrospinning and hot-pressing, using strategies of multi-layered structure and two fillers synergy of nickel modified carbon nanotube (Ni-CNT) and Al2O3 microspheres. The composite film consisted of a Ni-CNT filled PVDF electrospun fiber film as the top and bottom surface layers, and a PVDF electrospun fiber film electrostatically adsorbing Al2O3 microspheres and surface-sprayed with Ni-CNT as the middle layer. At a 20 wt% Ni-CNT in the surface layers and a 16.7 wt% Al2O3 and 5 wt% Ni-CNT in the middle layer, the composite film with a thickness of 0.1 mm exhibited optimal performances with electromagnetic wave shielding efficiency of 65 dB in the frequency range of 8.2–12.4 GHz, with 86% of the electromagnetic waves being absorbed. At the same time, the composite film had a high in-plane thermal conductivity of 4.02 W m−1 K−1, while maintaining a tensile strength of 25 MPa and flexibility.

Investigations on morphology, tribology, rheology, thermo-mechanical properties, and EMI shielding of WC/MWCNT nanohybrids in polypropylene

This study is focused to explore the synergism of dual nanofillers (tungsten carbide (WC) and multiwalled carbon nanotubes (MWCNTs)) in melt extruded PP composites. The synergy of fillers in PP enhanced the elastic modulus, tensile strength, and critical stress intensity factor by 141.8%, 35.4%, and 62.6%, respectively, at an optimum filler content of 1 wt% of WC and 2 wt% of MWCNTs. In the hybrid composites, activation energy to initiate thermal decomposition raised by 78% and wear resistance increased by 93%, and the hybrid composites exhibited enhanced reflectivity in the X band region, which contributed to high electromagnetic shielding effectiveness. The improvement in the properties makes the current hybrid composite system an ideal candidate in application sectors where high modulus, energy absorption, and thermal stability are required.

Quasi-Hyperbolic Framework Graphite Foam-Based Composites with High Thermal Conductivity and Electromagnetic Shielding Properties Fabricated by an Electrochemical Expansion Method.

Nowadays, the rapid development of electronic devices requires composites with high thermal conductivity and good electromagnetic shielding properties. The key challenge lies in the construction of high-performance conductive networks. Herein, an electrochemical expansion graphite foam (EEG) with a quasi-hyperbolic framework was prepared by an electrochemical expansion method, and then the epoxy resin (EP) was filled to fabricate the composites. The graphite plate was first electrochemically intercalated and then foamed, in which plasticization was caused by weak oxidation in intercalation and the quasi-hyperbolic framework was induced by foaming during expansion. These processes were characterized by Fourier transform infrared (FTIR), micro-Raman, X-ray photoelectron spectroscopy (XPS), and so on. Based on the highly efficient quasi-hyperbolic framework and high-quality graphite structure, the thermal conductivity of the composite reached 43.523 W/(m·K), and total electromagnetic interference (EMI) shielding (SET) reached 105 dB. The heat transfer behavior was simulated by finite element analysis (FEA) in detail. This method of preparing high thermal conductivity and electromagnetic shielding materials has a good application prospect.

Research Progress and the Prospect of Damping Magnesium Alloys.

As the lightest structural metal material, magnesium alloys possess good casting properties, high electrical and thermal conductivity, high electromagnetic shielding, and excellent damping properties. With the increasing demand for lightweight, high-strength, and high-damping structural materials in aviation, automobiles, rail transit, and other industries with serious vibration and noise, damping magnesium alloy materials are becoming one of the important development directions of magnesium alloys. A comprehensive review of the progress in this field is conducive to the development of damping magnesium alloys. This review not only looks back on the traditional damping magnesium alloys represented by Mg-Zr alloys, Mg-Cu-Mn alloys, etc. but also introduces the new damping magnesium materials, such as magnesium matrix composites and porous magnesium. But up to now, there have still been some problems in the research of damping magnesium materials. The effect of spiral dislocation on damping is still unknown and needs to be studied; the contradiction between damping performance and mechanical properties still lacks a good balance method. In the future, the introduction of more diversified damping regulating methods, such as adding other elements and reinforcements, optimizing the manufacturing method of damping magnesium alloy, etc., to solve these issues, will be the development trend of damping magnesium materials.

2D/0D multiscale interfacial engineering of carbon fiber composites for simultaneous achieving high mechanical and electromagnetic interference shielding properties

AbstractIn the face of escalating electromagnetic pollution, it is urgently needed to expedite the development of innovative carbon fiber reinforced polymer (CFRP) composites that not only demonstrate superior mechanical properties as well as durability but also boast exceptional electromagnetic interference shielding (EMI) performance. However, given the absence of robust interface interactions and the lack of an outstanding nanostructured conductive network, there remains a need to further elevate the overall performance of CFRP composites. Herein, a highly continuous conductive network by integrating 2D MXene and 0D Ag nanoparticles with strong interlayer interactions was constructed through point‐to‐plane conductive modes, facilitated by polydopamine (PDA). Thanks to the excellent electromagnetic wave loss and the unique multi‐dimensional structure arising from the optimizing interfacial engineering, the EMI shielding effectiveness of the modified CF‐PDA‐M‐Ag/EP composite achieved a remarkable 45.9 dB, obtaining a 99.5% enhancement compared with the neat CF/EP. The synergistic effect resulting from the multi‐dimensional structure and strong interaction can improve the interfacial shear strength (IFSS), interlaminar shear strength (ILSS) and flexure strength of the composite up to 81.9, 85.8 and 864.6 MPa, respectively, far superior to the unmodified composite materials. This research provides a dependable and convenient approach for exploiting high‐performance CFRP composites with intriguing electromagnetic interference (EMI) shielding properties.Highlights An optimizing multifunctional 2D/0D interface for carbon fiber was designed. A highly conductive network via the point‐to‐plane conductive mode. The EMI shielding effectiveness of the composite reached up to 45.9 dB.

Flexible sandwich-structured MXene@CNT/SA@MXene film with high electromagnetic shielding performance

Flexible sandwich-structured MXene@CNT/SA@MXene film with high electromagnetic shielding performance

Facile synthesis of O/N co-doped hierarchical porous carbon: for high performance supercapacitors and electromagnetic interference shielding

Biomass can be used to prepare carbon materials with excellent pore structures and rich surface properties based on its chemical properties, and have great potential in electrochemical energy storage and electromagnetic interference shielding.

Preparation and high electromagnetic shielding effectiveness of Cu/FeSiBCuNb/Cu sandwich structural composites

Preparation and high electromagnetic shielding effectiveness of Cu/FeSiBCuNb/Cu sandwich structural composites

BaZrO3/MgO-templated epitaxy showing a conductivity increase of three orders of magnitude for the Ba0.95La0.05SnO3 films on Al2O3 substrates, with very high transparency and X-band electromagnetic shielding

Transparent conductors with electromagnetic shielding capabilities (TC-EMS) are rare, despite their significant potential for creating new functionalities in energy and military applications. Here, we investigate the potential of La-doped BaSnO3 (BLSO) for TC-EMS since its epitaxial film has been known to have low sheet resistance and high visible transmittance. However, films grown on industrially practical Al2O3 substrates exhibit a sheet resistance three orders of magnitude higher than that of reported films grown on perovskites. Here, this problem is addressed by templating a BaZrO3/MgO bilayer on (0001)-oriented Al2O3 substrates to yield single-crystalline BLSO epitaxial films. The absence of grain boundaries in the epitaxial films minimizes the electron scattering. Due to the affirmative correlation between the conductivity and crystallinity, 5% La doping is optimal among the 5−20% La concentrations studied; these 480-nm-thick films have the highest crystallinity and the lowest sheet resistances of ~28 Ω ▯−1; this value is similar to that of single-crystalline levels. Due to their very high transmittances (~82% in a range 400−1000 nm) and effective X-band electromagnetic shielding (~18.6 dB), the BLSO epitaxial films grown on Al2O3 have great potential to be used for inexpensive TC-EMS applications.

Polypyrrole coated carbon fiber/ magnetite/ graphene oxide reinforced hybrid epoxy composites for high strength and electromagnetic interference shielding

Carbon fiber reinforced polymer composites (CFRPs) are in huge demand in the aviation industry for reducing fuel consumption despite their unfavorable electromagnetic interference (EMI) shielding properties. The present work aims to improve the mechanical properties and EMI shielding effectiveness (SE) of polypyrrole (PPy) coated carbon fibers/graphene oxide (GO)/magnetite nanoparticles (MP)/ epoxy hybrid composites. For this purpose, PPy was coated on desized woven carbon fibers (CFs) woven mats via electrophoretic deposition. Graphite oxide and magnetite nanoparticles were synthesized through improved Hummers’ method and modified Massart’s method, respectively. GO was synthesized via ultra-sonication of graphite oxide, with its average thickness determined to be ∼ 1.4 nm as verified by atomic force microscopy (AFM). Solution mixing method and vacuum centrifugal mixing were utilized to disperse GO in epoxy resin. Porosity-free composites were fabricated using the vacuum bag technique. PPy coating, graphite oxide, GO and MP were characterized by scanning electron microscopy (SEM), AFM and Fourier transform infrared spectroscopy (FTIR). The SEM images showed the globular morphology of the deposited PPy on CFs. Hybrid composites containing CFPPy-0.2 wt% GO-0.2 wt% MP showed ∼52%, ∼24%, ∼60% and ∼25% increase in tensile strength, Young’s modulus, toughness, and elongation, respectively, compared to neat CF-epoxy composite. All hybrid composites prepared in this work have SE > 30 dB and could be promising lightweight and high-strength materials for EMI shielding applications in the X-band frequency range.

MP/tubular-CF composite carbon foam of high microwave absorption and electromagnetic interference shielding properties

The MWA material hopes to achieve sufficiently low reflection loss, while the EMI shielding pursues sufficiently high electromagnetic shielding efficiency. At present, EMI shielding materials pursue sufficiently low reflection losses to avoid secondary pollution of electromagnetic waves. Therefore, it is the goal pursued by researchers of developing a material with enough high absorption loss and sufficiently low reflection loss. For this purpose, mesophase pitch/hollow carbon fiber composite carbon foam (MP/tubular-CF) was prepared by high-pressure pyrolysis. It was found that tubular-CF could effectively regulate the pore cell structure of the MP/tubular-CF. Meanwhile, tubular-CFs distributed randomly form a complete conductive network in composites, thereby improving the dielectric loss performance of composites. In addition, tubular-CF distributed randomly in composites result in more defects and heterogeneous interfaces which enhancing the electromagnetic wave loss performance. Of the prepared samples, MP/tubular-CF-9 exhibits the minimum reflection loss (RLmin) of −37.84 dB, as high as 32.47 dB of average total shielding efficiency, and 15.06 MPa of compressive strength simultaneously. This work proved a strategy that the synergistic regulation of pore cell structure, conductivity and defects are achieved in the process of composites preparation, which enables the composites to obtain simultaneously excellent MWA performance, EMI shielding performance and compressive strength.

La-doped BaSnO3 for electromagnetic shielding transparent conductors

In this work, we find that La-doped BaSnO3 (BLSO) is shown to be a promising electromagnetic shielding transparent conductor. While films grown on industrially practical optoelectronic MgAl2O4 substrates have higher sheet resistance by three orders of magnitude than in previous reports, we show how to recover the sheet resistance close to the single-crystal level by use of an MgO template layer which enables high quality (001)-oriented BLSO epitaxial film growth on (001) MgAl2O4. There is a positive correlation between crystallinity and conductivity; high crystallinity minimizes scattering of free electrons. By applying this design principle to 5–20% doped films, we find that highly crystalline 5% La-doped BLSO films exhibit low sheet resistance of ~ 8.7 Ω ▯ −1, high visible transmittance of ~ 80%, and high X-band electromagnetic shielding effectiveness of ~ 25.9 dB, thus outperforming transparent conducting oxides films of Sn-doped In2O3 and SrMoO3.Graphical

Research on Processability and Transmission Performance of Low Temperature Co-Fired Ceramic Ball Grid Array Packaging Based on Electroless Plating Surface Modification for Microwave Transceiver Circuits.

A microwave transmitter/receiver using the low-temperature co-fired ceramic substrate and ball grid array packaging demonstrates superior properties, including high integration, miniaturization, and high electromagnetic shielding. However, it holds limitations of inadequate hermeticity (that is, gas or moist impermeability), high cost, and low reproducibility. In this work, we aim to overcome these difficulties by introducing a new packing technique. The packaging utilizes an electroless plated Ni/Pd/Au surface, resulting in a significant enhancement of the packaging hermeticity by orders of magnitude, approaching the level of <5 × 10-9 Pa·m3/s. Both Sn63Pb37 and Au80Sn20 solder alloys demonstrate exceptional solderability, attributed to Pd atoms diffusing to the Au layer during soldering at 310 °C. A reliability test of the packaging shows that the shear strength of the solder balls drops after thermal shocks but negligibly affects the hermeticity of the packaging. Furthermore, a meticulously designed internal vertical interconnect structure and I/O interconnections were engineered in the ball grid array packaging, showcasing excellent transmission characteristics within the 10-40 GHz frequency range while ensuring effective isolation between ports.

Graphenization of graphene oxide films for strongly anisotropic thermal conduction and high electromagnetic interference shielding

A macroscopic carbon film that has a “graphenic” structure (defect-free in-plane graphene lattice yet absence of Bernal type graphitic stacking order), may inherit the exotic properties of rotated/slipped few-layer graphene (e.g., high flexibility and anisotropic transport properties). However, the fabrication of such a film remains challenging and unreported. Here we show that the annealing of reduced electrochemical graphene oxide (REGO), which has fewer in-plane defects than the conventional graphene oxide from Hummers’ method, leads to a nearly intact graphene lattice (Raman ID/IG down to 0.03) without restoring the graphitic stacking order (I2D/IG > 1 and a single Lorentzian 2D peak). Atomic resolution transmission electron microscopy verifies the unique graphenic structure with random interlayer rotations. Density functional theory calculations imply the low defect density of REGO can suppress the interplanar interaction between undercoordinated carbon atoms, therefore inhibiting cross-plane migration of vacancies and the consequent establishment of stacking order. The annealed, graphenic REGO film is highly flexible and has an in-plane to cross-plane thermal conductivity ratio of 835 (among the highest reported for anisotropic thermal conductors). This high anisotropic ratio is attributed to the inhibited through-plane heat transport (0.26 W m−1 K−1) by the interlayer rotations and the high in-plane thermal conductivity (218 W m−1 K−1) enabled by intact graphene lattice. The graphenic films show high electromagnetic interference shielding effectiveness of 80.3 dB at a thickness of 53 μm and 42.4 dB at 5.7 μm, with an absolute effectiveness (>70000 dB cm2 g−1) superior to two-dimensional metal carbides (MXenes) and Al foil.