Bioinspired Polymer Nanocomposites Exhibit Giant Energy Density and High Efficiency at High Temperature

Polymer dielectrics are ubiquitous in advanced electric energy storage systems. However, the relatively low operating temperature significantly menaces their widespread application at high temperatures, such as for hybrid vehicles and aerospace power electronics. Spider silk, a natural nanocomposite comprised of biopolymer chains and crystal protein nanosheets combined by multiple interfacial interactions, exhibits excellent mechanical properties even at elevated temperatures. Inspired by the hierarchical nanostructure of spider silk, poly(aryl ether sulfone) is anchored to the surface of wide bandgap artificial nanosheets to prepare the nanocomposites with nanoconfinement effect. The bioinspired strategy successfully improves the mechanical and electrical performances of the nanocomposite. Owing to the structural‐enabled enhancements, the nanocomposites exhibit excellent breakdown strength and electrical energy storage performance at high temperatures. In detail, giant discharged energy density (2.7 J cm^?3) and high charge–discharge efficiency (>90%) are simultaneously achieved at 150 °C and 400 MV m^?1. Notably, under 500 MV m^?1, the discharged energy density reaches 4.2 J cm^?3, which is the record high discharged energy density among polymer‐based dielectrics at 150 °C. This work demonstrates a viable strategy to design high‐temperature polymer dielectrics by constructing nanoconfinement in the nanocomposites.     

Flexible Temperature-Invariant Polymer Dielectrics with Large Bandgap

Flexible dielectrics operable under simultaneous electric and thermal extremes are critical to advanced electronics for ultrahigh densities and/or harsh conditions. However, conventional high-performance polymer dielectrics generally have conjugated aromatic backbones, leading to limited bandgaps and hence high conduction loss and poor energy densities, especially at elevated temperatures. A polyoxafluoronorbornene is reported, which has a key design feature in that it is a polyolefin consisting of repeating units of fairly rigid fused bicyclic structures and alkenes separated by freely rotating single bonds, endowing it with a large bandgap of ≈5 eV and flexibility, while being temperature-invariantly stable over −160 to 160 °C. At 150 °C, the polyoxafluoronorbornene exhibits an electrical conductivity two orders of magnitude lower than the best commercial high-temperature polymers, and features an unprecedented discharged energy density of 5.7 J cm⁻³ far outperforming the best reported flexible dielectrics. The design strategy uncovered in this work reveals a hitherto unexplored space for the design of scalable and efficient polymer dielectrics for electrical power and electronic systems under concurrent harsh electrical and thermal conditions.     

High‐Performance Polymers Sandwiched with Chemical Vapor Deposited Hexagonal Boron Nitrides as Scalable High‐Temperature Dielectric Materials

Polymer dielectrics are the preferred materials of choice for power electronics and pulsed power applications. However, their relatively low operating temperatures significantly limit their uses in harsh‐environment energy storage devices, e.g., automobile and aerospace power systems. Herein, hexagonal boron nitride (h ‐BN) films are prepared from chemical vapor deposition (CVD) and readily transferred onto polyetherimide (PEI) films. Greatly improved performance in terms of discharged energy density and charge–discharge efficiency is achieved in the PEI sandwiched with CVD‐grown h ‐BN films at elevated temperatures when compared to neat PEI films and other high‐temperature polymer and nanocomposite dielectrics. Notably, the h ‐BN‐coated PEI films are capable of operating with >90% charge–discharge efficiencies and delivering high energy densities, i.e., 1.2 J cm^?3, even at a temperature close to the glass transition temperature of polymer (i.e., 217 °C) where pristine PEI almost fails. Outstanding cyclability and dielectric stability over a straight 55 000 charge–discharge cycles are demonstrated in the h ‐BN‐coated PEI at high temperatures. The work demonstrates a general and scalable pathway to enable the high‐temperature capacitive energy applications of a wide range of engineering polymers and also offers an efficient method for the synthesis and transfer of 2D nanomaterials at the scale demanded for applications.     

Tailoring Poly(Styrene-co-maleic anhydride) Networks for All-Polymer Dielectrics Exhibiting Ultrahigh Energy Density and Charge–Discharge Efficiency at Elevated Temperatures

Polymer film capacitors have been widely used in electronics and electrical power systems due to their advantages of high power densities, fast charge–discharge speed, and great stability. However, the exponential increase of electrical conduction with temperature and applied electric field substantially degrades the capacitive performance of dielectric polymers at elevated temperatures. Here, the first example of controlling the energy level of charge traps in all-organic crosslinked polymers by tailoring molecular structures that significantly inhibit high-field high-temperature conduction loss, which largely differs from current approaches based on the introduction of inorganic fillers, is reported. The polymer network with optimized crosslinking structures exhibits an ultrahigh discharged energy density of 7.02 J cm⁻³ with charge/discharge efficiencies of >90% at 150 °C, far outperforming current dielectric polymers and composites. The charge-trapping effects in different crosslinked structures, as the origins of the marked improvements in the high-temperature capacitive performance, are comprehensively investigated experimentally and confirmed computationally. Moreover, excellent cyclability and self-healing features are demonstrated in the polymer film capacitors. This work offers a promising pathway of molecular structure design to scalable high-energy-density polymer dielectrics capable of operating under harsh environments.     

Improved Capacitive Energy Storage Nanocomposites at High Temperature Utilizing Ultralow Loading of Bimetallic MOF

It is urgent to develop high-temperature dielectrics with high energy density and high energy efficiency for next-generation capacitor demands. Metal-organic frameworks (MOFs) have been widely used due to their structural diversity and functionally adaptable properties. Doping of metal nodes in MOFs is an effective strategy to change the band gap and band edge positions of the original MOFs, which helps to improve their ability to bind charges as traps. In this work, the incorporation of ultralow loading (<1.5 wt%) of novel bimetallic MOFs (ZIF 8–67) into the polyetherimide (PEI) polymer matrix is exhibited. With the addition of ZIF 8–67, the breakdown strength and energy storage capacity of ZIF 8–67/PEI nanocomposites are significantly improved, especially at high temperatures (200 °C). For example, the energy densitiy of the 0.5 wt% ZIF 8–67/PEI nanocomposite is up to 2.96 J cm⁻³, with an efficiency (η) > 90% at 150 °C. At 200 °C, the discharge energy density of 0.25 wt% ZIF 8–67/PEI nanocomposites can still reach 1.84 J cm⁻³ with a η > 90%, which is nine times higher than that of pure PEI (0.21 J cm⁻³) under the same conditions, and it is the largest improvement compared with the previous reports.     

Scalable Polymer Nanocomposites with Record High‐Temperature Capacitive Performance Enabled by Rationally Designed Nanostructured Inorganic Fillers

Next‐generation microelectronics and electrical power systems call for high‐energy‐density dielectric polymeric materials that can operate efficiently under elevated temperatures. However, the currently available polymer dielectrics are limited to relatively low working temperatures. Here, the solution‐processable polymer nanocomposites consisting of readily prepared Al₂O₃ fillers with systematically varied morphologies including nanoparticles, nanowires, and nanoplates are reported. The field‐dependent electrical conduction of the polymer nanocomposites at elevated temperatures is investigated. A strong dependence of the conduction behavior and breakdown strength of the polymer composites on the filler morphology is revealed experimentally and is further rationalized via computations. The polymer composites containing Al₂O₃ nanoplates display a record capacitive performance, e.g., a discharged energy density of 3.31 J cm^?3 and a charge–discharge efficiency of >90% measured at 450 MV m^?1 and 150 °C, significantly outperforming the state‐of‐the‐art dielectric polymers and nanocomposites that are typically prepared via tedious, low‐yield approaches.     

Negatively Charged Nanosheets Significantly Enhance the Energy-Storage Capability of Polymer-Based Nanocomposites

Polymer-based dielectric materials play a key role in advanced electronic devices and electric power systems. Although extensive research has been devoted to improve their energy-storage performances, it is a great challenge to increase the breakdown strength of polymer nanocomposites in terms of achieving high energy density and good reliability under high voltages. Here, a general strategy is proposed to significantly improve their breakdown strength and energy storage by adding negatively charged Ca₂Nb₃O₁₀ nanosheets. A dramatically enhanced breakdown strength (792 MV m⁻¹) and the highest energy density (36.2 J cm⁻³) among all flexible polymer-based dielectrics are observed in poly(vinylidene fluoride)-based nanocomposite capacitors. The strategy generalizability is verified by the similar substantial enhancements of breakdown strength and energy density in polystyrene-based nanocomposites. Phase-field simulations demonstrate that the further enhanced breakdown strength is ascribed to the local electric field, produced by the negatively charged Ca₂Nb₃O₁₀ nanosheets sandwiched with the positively charged polyethyleneimine, which suppresses the secondary impact-ionized electrons and blocks the breakdown path in nanocomposites. The results demonstrate a new horizon of high-energy-density flexible capacitors.     

Carboxylated Poly (p-Phenylene Terephthalamide) Reinforced Polyetherimide for High-Temperature Dielectric Energy Storage

Dielectric energy storage polymers play a vital role in advanced electronics and electrical systems, due to their high breakdown strength, excellent reliability, and easy fabrication. However, the low dielectric constant and poor thermal resistance of dielectric polymers limit their energy storage density and working temperatures, making them less versatile for broader applications. In this work, a novel carboxylated poly (p-phenylene terephthalamide) (c-PPTA) is synthesized and employed to simultaneously enhance the dielectric constant and thermal resistance of polyetherimide (PEI), leading to a discharged energy density of 6.4 J cm⁻³ at 150 °C. The introduction of c-PPTA molecules effectively reduces the Π Π stacking effect and increases the average chain spacing between polymer molecules, which is conducive to improving the dielectric constant. Additionally, c-PPTA molecules with stronger positive charges and high dipole moments can capture electrons, resulting in reduced conduction loss and enhanced breakdown strength at high temperatures. The coiled capacitor fabricated with the PEI/c-PPTA film exhibits superior capacitance performances and higher working temperatures compared to commercial metalized PP capacitors, demonstrating great potential for dielectric polymers in high-temperature electronic and electrical energy storage systems.     

Superior Energy Storage Capability and Stability in Lead-Free Relaxors for Dielectric Capacitors Utilizing Nanoscale Polarization Heterogeneous Regions

The development of high-performance lead-free dielectric ceramic capacitors is essential in the field of advanced electronics and electrical power systems. A huge challenge, however, is how to simultaneously realize large recoverable energy density (W_rec), ultrahigh efficiency (η), and satisfactory temperature stability to effectuate next-generation high/pulsed power capacitors applications. Here, a strategy of utilizing nanoscale polarization heterogeneous regions is demonstrated for high-performance dielectric capacitors, showing comprehensive properties of large W_rec (≈6.39 J cm⁻³) and ultrahigh η (≈94.4%) at 700 kV cm⁻¹ accompanied by excellent thermal endurance (20–160 °C), frequency stability (5–200 Hz), cycling reliability (1–105 cycles) at 500 kV cm⁻¹, and superior charging-discharging performance (discharge rate t_0.9 ≈ 28.4 ns, power density PD ≈161.3 MW cm⁻³). The observations reveal that constructing the polarization heterogeneous regions in a linear dielectric to form novel relaxor ferroelectrics produces favorable microstructural characters, including extremely small polar nanoregions with high dynamics and multiphase coexistence and stable local structure symmetry, which enables large breakdown strength and ultralow polarization switching hysteresis, hence synergistically contributing to high-efficient capacitive energy storage. This study thus opens up a novel strategy to design lead-free dielectrics with comprehensive high-efficient energy storage performance for advanced pulsed power capacitors applications.     

Interface‐Strengthened Polymer Nanocomposites with Reduced Dielectric Relaxation Exhibit High Energy Density at Elevated Temperatures Utilizing a Facile Dual Crosslinked Network

High‐temperature ceramic/polymer nanocomposites with large energy density as the reinforcement exhibit great potential for energy storage applications in modern electronic and electrical power systems. Yet, a general drawback is that the increased dielectric constant is usually achieved at the cost of decreased breakdown strength, thus leading to moderate improvement of energy density and even displaying a marked deterioration under high temperatures and high electric fields. Herein, a new strategy is reported to simultaneously improve breakdown strength and discharged energy density by a step‐by‐step, controllable dual crosslinking process, which constructs a strengthened interface as well as reduces molecular chains relaxation under elevated temperatures. Great breakdown strength and discharged energy density is achieved in the dual crosslinked network BT‐BCB@DPAES nanocomposites at elevated temperatures when compared to noninterfacial‐strengthened, BT/DPAES composites, i.e., an enhanced breakdown strength and a discharged energy density of 442 MV m^?1 and 3.1 J cm^?3, increasing by 66% and 162%, and a stable cyclic performance over 10 000 cycles is demonstrated at 150 °C. Moreover, the enhancement through the synergy of two crosslinked networks is rationalized via a comprehensive phase‐field model for the composites. This work offers a strategy to enhance the electric storage performances of composites at high temperatures.     

Highly Thermoconductive,Thermostable, and Super-Flexible Film by Engineering 1D Rigid Rod-Like Aramid Nanofiber/2D Boron Nitride Nanosheets

Polymer-based thermal management materials have many irreplaceable advantages not found in metals or ceramics, such as easy processing, low density, and excellent flexibility. However, their limited thermal conductivity and unsatisfactory resistance to elevated temperatures (<200 °C) still prevent effective heat dissipation during applications with high-temperature conditions or powerful operation. Therefore, herein highly thermoconductive and thermostable polymer nanocomposite films prepared by engineering 1D aramid nanofiber (ANF) with worm-like microscopic morphologies into rigid rod-like structures with 2D boron nitride nanosheets (BNNS) are reported. With no coils or entanglements, the rigid polymer chain enables a well-packed crystalline structure resulting in a 20-fold (or greater) increase in axial thermal conductivity. Additionally, strong interfacial interactions between the weaved ANF rod and the stacked BNNS facilitate efficient heat flux through the 1D/2D configuration. Hence, unprecedented in-plane thermal conductivities as high as 46.7 W m⁻¹ K⁻¹ can be achieved at only 30 wt% BNNS loading, a value of 137% greater than that of a worm-like ANF/BNNS counterpart. Moreover, the thermally stable nanocomposite films with light weight (28.9 W m⁻¹ K⁻¹/10³ (kg m⁻³)) and high strength (>100 MPa, 450 °C) enable effective thermal management for microelectrodes operating at temperatures beyond 200 °C.     

Active carbon/graphene hydrogel nanocomposites as a symmetric device for supercapacitors

Activated carbons (ACs) are successfully synthesized from Elaeagnus grain by a simple chemical synthesis methodology and demonstrated as novel, suitable supercapacitor electrode materials for graphene hydrogel (GH)/AC nanocomposites. GH/AC nanocomposites are synthesized via hydrothermal process at temperature of 180°C. The low-temperature thermal exfoliation approach is convenient for mass production of graphene hydrogel (GH) at low cost and it can be used as electrode material for energy storage applications. The GH/AC nanocomposites exhibit better electrochemical performances than the pure GH. Electrochemical performance of the electrodes is studied by cyclic voltammetry, and galvanostatic charge-discharge measurements in 1.0 M H₂SO₄ solution. A remarkable specific capacitance of 602.36 Fg^?1 (based on GH/AC nanocomposites for 0.4 g AC) is obtained at a scan rate of 1 mVs^?1 in 1 M H₂SO₄ solution and 155.78 Fg^?1 for GH. The specific capacitance was increased 3.87 times for GH/AC compared to GH electrodes. Moreover, the GH/AC nanocomposites for 0.2 g AC present excellent long cycle life with 99.8% specific capacitance retained after 1000 charge/discharge processes. Herein, ACs prepared from Elaeagnus grain are synthesized GH and AC supercapacitor device for high-performance electrical energy storage devices as a promising substitute to conventional electrode materials for EDLCs.     

Air-stable,earth-abundant molten chlorides and corrosion-resistant containment for chemically-robust,high-temperature thermal energy storage for concentrated solar power

A dramatic reduction in man-made CO₂ emissions could be achieved if the cost of electricity generated from concentrated solar power (CSP) plants could become competitive with fossil-fuel-derived electricity. The solar heat-to-electricity conversion efficiency of CSP plants may be significantly increased (and the associated electricity cost decreased) by operating CSP turbines with inlet temperatures ≥750 °C instead of ≤550 °C, and by using thermal energy storage (TES) at ≥750 °C to allow for rapidly dispatchable and/or continuous electricity production. Unfortunately, earth-abundant MgCl₂–KCl-based liquids currently being considered as low-cost media for large-scale, high-temperature TES are susceptible to oxidation in ambient air, with associated undesired changes in liquid composition and enhanced corrosion of metal alloys in pipes and tanks containing such liquids. In this paper, alternative high-temperature, earth-abundant molten chlorides that are resistant to oxidation in ambient air are identified via thermodynamic calculations. The oxidation resistance, and corrosion-resistant containment, of such molten chlorides at 750 °C are then demonstrated. Such an air-tolerant strategy, involving chemically-robust, low-cost TES media paired with effective containment materials, provides a critical advance towards the higher-temperature operation of, and lower-cost electricity generation from, CSP plants.     

Enhanced dielectric properties and energy storage density of surface engineered BCZT/PVDF-HFP nanodielectrics

Polymer nanocomposites have proved to be promising energy storage devices for modern power electronic systems. In this work we have studied the dielectric properties and dielectric energy storage densities of 0–3 type BCZT/PVDF-HFP polymer nanocomposites with different filler volume concentrations. BCZT nanopowder was synthesized by solgel method through citrate precursor method. The structural and morphological features of the BCZT nanopowder were examined by X-ray diffraction and transmission electron microscopy. For better polymer ceramic interface coupling, BCZT was surface functionalized with extended aromatic ligand, naphthyl phosphate (NPh). The surface functionalization was validated and quantified by thermogravimetric analysis and X-ray photoelectron spectroscopy. The dielectric constant of surface passivated BCZT nanoparticles was estimated to be ~?155 using slurry technique, while the dielectric permittivity of pristine BCZT nanopowder could not be assessed due to high innate surface conductivity. BCZT/PVDF-HFP polymer nanocomposite thin films were fabricated using solution casting technique. The dispersion quality of the ceramic fillers in the polymer matrix was examined by scanning electron microscopy. Due to better polymer ceramic interface, At 5 vol% filler concentration, NPh modified nanoBCZT/PVDF-HFP films showed enhanced dielectric breakdown strength and energy storage density than untreated nanoBCZT/PVDF-HFP and even pure polymer films. Maximum energy storage density of 8.5 J cm^?3 was obtained at an optimum filler concentration of 10 vol% for surface functionalized BCZT/PVDF-HFP composite films of 10 μm thickness.     

Simultaneous enhancement of breakdown strength and discharged energy efficiency of tri-layered polymer nanocomposite films by incorporating modified graphene oxide nanosheets

Developing high dielectric performance of polymer nanocomposites is still a long-standing issue to simultaneously inherit the high dielectric constant of nanofillers and maintain the high breakdown strength of polymer matrix. In the current study, a tri-layered nanocomposite film is fabricated by a simple and effective solution-casting and dip-coating method, where graphene oxide nanosheets (GONSs) were modified by insulating SiO₂ layer (SiO₂@GONSs) and polyvinylidene fluoride (PVDF)/SiO₂@GONS nanocomposite inner layer was sandwiched by polycarbonate (PC) layers. The surface modification could minimize the local electric field concentration and block conductive path. Furthermore, the sandwich or tri-layered structure inhibited the relaxation and migration of space charge or impurity ions and suppressed the charge injection, thus achieving enhanced breakdown strength and discharged energy efficiency. As a result, the as-prepared tri-layered nanocomposite film exhibited a dielectric constant of 5.2 and a low dielectric loss (tanδ) of 0.013 at 1 kHz, and breakdown strength of 219 MV m^?1, which was significantly higher than single-layered nanocomposite films and its counterpart without SiO₂ modification. The corresponding discharged energy density was 1.20 J cm^?3 with an excellent efficiency of 86.2% at 200 MV m^?1. More interestingly, the insulating SiO₂ modification layer and PC outer layers could also effectively restrict the relaxation or migration of impurity ions at a high temperature of 120 °C, endowing excellent high-temperature dielectric performance to the as-prepared tri-layered nanocomposite film. The combination of surface modification and sandwich structure opens up an avenue to fabricate GONS-based dielectric nanocomposites with low dielectric loss, high breakdown strength, high efficiency and high temperature tolerance.

Graphical abstract

     

Nanostructures bilayer ZnO/MgO dielectrics for metal–insulator–metal capacitor applications

Bilayer ZnO/MgO dielectrics for metal–insulator–metal (MIM) capacitor application were successfully deposited using simple chemical technique which is sol–gel spin coating method with different annealing temperatures. Important criteria in determining good dielectric layer have been investigated which include structural, electrical and dielectric properties. Cubic-like grain was observed for films annealed at 400 and 425 °C which enhance the carrier density and polarization that resulted in high k value produced. Bilayer film annealed at 475 °C improved in small surface roughness (17.629 nm), minimum leakage current density (~10^?8 A cm^?2) and high resistivity (3.14 × 10⁵ Ω cm). Dielectric constant, k was varied with frequency and k value was found to be 5.09 at 10 kHz. The results obtained in this study indicated that film annealed at temperature of 475 °C is suitable to be used as dielectrics for MIM capacitor application.     

Thermal stability and electrical characteristics of poly(2-ethyleaniline)-Au nanocomposite

The Present work reports the synthesis of poly2-ethyleaniline (PEANI) by oxidative polymerization of 2-ethyleaniline and its composite with gold nanoparticles (AuNPs) via in situ chemical synthesis route (simultaneous polymerization and precipitation). PEANI and its nanocomposite were characterized by thermogravimetric analysis-differential Scanning Calorimetry, X-ray diffraction and Fourier transform-infrared. The structural confirmation of the polymer was confirmed by FT-IR which shows strong absorption starting at ~1,600 cm^?1 and extended to near-IR, Attributed to the presence of free carrier in the polymer. XRD of Polymer shows large X-rays peaks indicating that the material is rather amorphous with a certain degree of crystallinity where as XRD of PEANI-Au nanocomposite confirms the incorporation of AuNPs in composite. The TEM image showed the formation of PEANI-AuNPs core shell nanostructure. From TGA–DSC studies it was confirmed that the decomposition of the polymer in the composite is lowered by 254 °C as compare to PEANI alone, resulting in weak structure. Whereas I–V characteristics’ shows that the composite has about 10 % lower conductance values than the polymer alone.     

Rapid fabrication of hierarchical porous SiC/C hybrid structure: toward high-performance capacitive energy storage with ultrahigh cyclability

Nanostructured silicon carbide (SiC) materials are expected to have bright prospect in application as high-performance electrode materials with excellent charge–discharge cycling stability. However, the exploration of SiC-based micro-supercapacitors (MSCs) still remains a grand challenge seriously hampered by low areal capacities and complicated multistep production process. Herein, we report that rationally designed SiC/C nanocomposite with hierarchical porous structure and improved electrical conductivity has been realized by a facile and rapid carbothermic reduction using silica sol and sucrose as silicon and carbon source. The amorphous carbon between SiC nanoparticles (NPs) contributes to enlarged surface areas and excellent conductivity, not only ensuring intimate contact between the electrolyte and the electrode but also providing an effective ion highway for electrolyte ions. As a result, MSCs based on SiC/C nanocomposite (Si/C mass ratio of 1:1.5) demonstrate an optimal specific areal capacitance of 11.8 mF cm^?2 at 2 mV s^?1, outstanding flexibility (104.5% retention of initial capacitance at 180° bending), and superior integration. Most notably, the capacitance remains at 97.3% of the initial value after 50000 charging/discharging cycles, superior to that of most advanced SiC-based MSCs ever reported. This work demonstrates an effective design for hierarchical porous SiC/C nanocomposite for energy storage, which gives significant inspirations on the exploration of high-performance SiC-based MSCs.

     

Microstructure and electrical properties of ZnO-based varistors prepared by high-energy ball milling

ZnO-based varistor ceramics were prepared at sintering temperatures ranging from 900 °C to 1,300 °C, by subjecting the mixed oxide powders to high-energy ball milling (HEBM) for 0, 5, 10 and 20 h, respectively. Varistor ceramics prepared by HEBM featured denser body, better electrical properties sintered at low-temperature than at traditional high-temperature. The high density is due to the refinement of the crystalline grains, the enhanced stored energy in the powders coming from lattice distortion and defects as well as the promotion of liquid-phase sintering. Good electrical properties is attributed to proper microstructure formed at low-temperature and improved grain boundary characteristics resulting from HEBM. With increasing sintering temperatures, the electrical properties and density became worse due to the decrease in amount of Bi-rich phase. Temperature increased up to 1,200 °C or above, the Bi-rich phase vanished and the ceramics exhibited very low nonlinear coefficient.     

Synthesis and properties of sandwiched films of epoxy resin and graphene/cellulose nanowhiskers paper

Graphene (GN)-based composite paper containing 10 wt.% cellulose nanowhiskers (CNWs) exhibiting a tensile strength of 31.3 MPa and electrical conductivity of 16 800 S/m was prepared by ultrasonicating commercial GN powders in aqueous CNWs suspension. GN/CNWs freestanding paper was applied to prepare the sandwiched films by dip coating method. The sandwiched films showed enhanced tensile strength by over two times higher than the neat resins. The moduli of the sandwiched films were around 300 times of the pure resins due to the high content of GN/CNWs paper. The glass transition temperature of the sandwiched films increased from 51.2 °C to 57.1 °C for pure epoxy (E888) and SF (E888), and 49.8 °C to 64.8 °C for pure epoxy (650) and SF (650), respectively. The bare conductive GN/CNWs paper was well protected by the epoxy resin coating, which is promising in the application as anti-static materials, electromagnetic interference (EMI) shielding materials.