Dielectric Filler Research Articles

Core–Shell Structured BaTiO3@Polyethylene in Low‐Density Polyethylene: Modulation of Dispersion Structure and Improvement of Dielectric Properties

ABSTRACTOrganically modified dielectric filler nanoparticles with core–shell structures have received widespread attention when designing composites with excellent dielectric properties. Herein, the core–shell structured BaTiO3@polyethylene (BT@PE) nanoparticles were prepared and the models of BT@PE filled low‐density polyethylene (LDPE) composites were constructed. The interaction modulated nanoparticle dispersion structure and the effect of the core–shell structured BT@PE on the polarization and breakdown of the composites were studied by molecular dynamics (MD) simulations and finite element analysis (FEA). The results show that BT@PE modulated the interactions between particles, formed a well‐dispersed structure in the LDPE matrix, and optimized the electric field distribution inside the composites. Moreover, due to the existence of microscopic transition layer, the core–shell structured BT@PE increased the interfacial polarization while suppressed the electric field distortion. BT@PE nanoparticles simultaneously enhanced the dielectric constant and breakdown strength of the composites.

Ultralow UV absorber content in 3D printed nanocomposites: maximizing printability and microwave absorption efficiency

Abstract The increasing prevalence of electromagnetic wave exposure in our daily life, particularly within the 100 MHz–300 GHz range, necessitates advancements in microwave absorption materials. This study explores the utilization of 3D printing and VAT photopolymerization to optimize material properties for efficient microwave absorption. While electrically conductive nanocomposites comprising dielectric matrices and conductive fillers have shown promise, their 3D printability poses challenges particularly because of strong UV absorption by conductive fillers. This work addresses this challenge by employing weakly UV absorbing graphene oxide (GO) as a functional surfactant to stabilize single-walled carbon nanotubes (SWCNTs) in an acrylic polymer matrix. The GO particles adsorb at the SWCNT interface. GO remains insulating until in-situ thermal reduction to reduced GO (rGO). After reduction, rGO at the SWCNT interface minimize electrical contact resistance between nanotubes, promoting thereby high conductivity of the nanotube network. The high aspect ratio and conductivity of SWCNTs, combined with the transparency and amphiphilic nature of GO, result in nanocomposites with enhanced electrical conductivity and minimal UV absorption. This allows for the 3D printing of conductive formulations with SWCNT contents as low as 0.03 wt%. This ultralow UV absorber content ensures excellent printability, with maximum cure depths exceeding 100 µm within seconds of UV irradiation. Moreover, the resulting nanocomposites exhibit promising microwave absorption properties in the S and Ku bands (2–4 and 12–18 GHz, respectively). Their reflexion losses, are below −10 dB over a 2.5 GHz bandwidth for a 4.75 mm thick layer. Emphasis is placed on the remarkable printability achieved in this study, as the microwave absorption properties remain unoptimized for specific applications.

A PVDF-HFP/YSZ nanofiber composite solid-state electrolyte by in-situ polymerization of 1,3-dioxolane for 4.5 V high-voltage NCM811 battery

Solid lithium metal batteries with solid polymer electrolytes have advantages in terms of high energy density and safety. However, their application is still hindered by unstable solid electrolyte interfaces (SEI and CEI) and uncontrolled dendrite growth. Here, a composite skeleton loaded with dielectric filler yttrium stabilized zirconia nanoparticles (YSZ) on the surface of PVDF-HFP nanofiber filaments is designed, and a novel composite solid electrolyte (CSE) is prepared by in-situ polymerization of DOL (1,3-dioxolane) on this framework to achieve safe and stable high-voltage lithium metal battery (LMB). The dual stable electrode interfaces (CEI and SEI) constructed by in-situ can effectively suppress the generation of lithium dendrites and suppress the degradation of the high-voltage NCM811 positive electrode structure and the generation of cracks in NCM811 particles, endowing the battery with extraordinary performance. The as-obtained CSE exhibits high ionic conductivity of 1.01 × 10−3 S cm−1 at 30 °C, the enlarged electrochemical window of 6.0 V, and the Li+ transference number is 0.72. The assembled Li|NCM811 battery is capable of stable cycling for 400 cycles at a cut-off voltage of 4.5 V and current density of 1C, with a capacity decay of only 0.074 % per cycle. .

Thermal interface materials of PDMS with h-BN fillers synthesized from ferroboron via SHS

Thermal interface materials (TIMs) are widely used to enhance heat transfer between heat-generating components of electronic devices and cooling radiators. The rapid miniaturization of electronic devices and the increase in their specific capacity have led to excessive heat loads, necessitating the development of TIMs based on dielectric powder fillers with high thermal conductivity. This paper presents an energy-efficient approach for synthesizing hexagonal boron nitride (h-BN) powder, used as a filler for thermal interface pads with a polydimethylsiloxane polymer matrix. The h-BN filler was produced through a two-step process: (1) self-propagating high-temperature synthesis of Fe-BN powder through the self-sustaining exothermic reaction of an affordable ferroboron powder with gaseous nitrogen, followed by (2) acid leaching of the synthesized powders to remove iron. The BN phase content in the resulting powder filler is 99.6 wt%. The pads demonstrated a thermal conductivity of up to 1.95 W m⁻1K⁻1 with a 40 wt% filler content and an average particle size of 40 μm, all while retaining adequate flexibility and elasticity.

Optimizing the dielectric properties of polymer composites by constructing multi-dimensional fillers

The construction of multidimensional fillers provides new ideas for the development of composite materials. In this study, one-dimensional (La0.5Nb0.5)xTi1-xO2 ceramic nanorods (x-LNTO NRs) and 1-LNTO ceramic materials with three-dimensional fiber structure network (3D-1-LNTO) were prepared by electrospinning. These materials were used as fillers to prepare x-LNTO NRs/PVDF composites and 3D-1-LNTO/PVDF composites. Compared with the 1-LNTO NPs/PVDF composites, the 1-LNTO NRs/PVDF composites showed better dielectric properties, with a dielectric constant of 40 and a dielectric loss of 0.12 at a fill content of 60 wt%. The 3D-1-LNTO/PVDF composites achieved a high dielectric constant at a low filler content, the composite achieved a dielectric constant of 25 at a fill content of only 10 wt%, which is 2.5 times higher than that of pure PVDF. Compared with x-LNTO NRs, 3D-1-LNTO is more obvious for improving the dielectric properties of composites. The construction of continuous fiber network is the main reason for the enhancement of dielectric constant, and this study provides a new experimental idea for the construction of multi-dimensional high dielectric fillers.

Trapping Ions to Enhance High-Field Energy Harvesting Performance by Filling Polar Macromolecular Dielectrics.

In the quest for sustainable and renewable energy sources, researchers and engineers have explored innovative technologies to harvest energy from various environmental sources. Dielectric elastomer generators (DEGs) with high energy harvesting performance have been proven to be promising energy collectors, but achieving a high dielectric constant (ε') and low electrical conductivity (EC) under high electric fields of dielectric elastomer (DE) simultaneously is a struggle, which poses significant challenges. In this study, high-content carboxyl group-grafted liquid polybutadiene (HCPB) is synthesized and then adopted as an organic dielectric filler to blend and cocross-link with a butadiene rubber (BR) matrix to prepare DE composites with high energy harvesting performance. The introduction of carboxyl groups enhances polarization while trapping free Al3+ in the matrix, which revolutionarily achieves a significant increase in ε' under extremely low EC. Ultimately, the contradiction between increased ε' and decreased EC under high electric fields is reconciled, resulting in a 30 HCPB/BR composite with high energy density (w = 91.9 mJ/cm3) and fine power conversion efficiency (PCE = 24.1%). This advancement paves the way for the development of HCPB/BR composite-based DEGs with enhanced ε' and energy harvesting performance.

Liquid metal interface mechanochemistry disentangles energy density and biaxial stretchability tradeoff in composite capacitor film

Dielectric polymer composites for film capacitors have advanced significantly in recent decades, yet their practical implementation in industrial-scale, thin-film processing faces challenges, particularly due to limited biaxial stretchability. Here, we introduce a mechanochemical solution that applies liquid metal onto rigid dielectric fillers (e.g. boron nitride), dramatically transforming polymer-filler interface characteristics. This approach significantly reduces modulus mismatch and stress concentration at the interface region, enabling polypropylene composites to achieve biaxial stretching ratio up to 450 × 450%. Furthermore, liquid metal integration enhances boron nitride’s dielectric polarization while maintaining inherent insulation, producing high-dielectric-constant, low-loss films. These films, only microns thick yet quasi square meters in area, achieve a 55% increase in energy density over commercial biaxially-oriented polypropylene (from 2.9 to 4.5 J cm−3 at 550 MV/m), keeping 90% discharge efficiency. Coupled with improved thermal conductivity, durability, and device capacitance, this distinctive interface engineering approach makes these composites promising for high-performance film capacitors.

Phosphor‐Loaded Triboelectric Film‐Based Multipurpose Triboelectric Nanogenerators for Highly‐Efficient Energy Harvesting, Sensing, and Self‐Illumination Applications

AbstractA novel approach is proposed for combining phosphor materials with triboelectric nanogenerators (TENGs) for mechanical energy harvesting and illumination applications. For this purpose, strongly reddish‐orange‐emitting Ba0.5Sr0.5Nb2O6:0.25 mol Eu3+ (BSNb:0.25Eu) phosphor materials are synthesized. The photoluminescence properties of the synthesized BSNb:0.25Eu are analyzed. The synthesized BSNb:0.25Eu is utilized as a dielectric filler inside a polydimethylsiloxane polymeric film due to its high dielectric properties to improve the overall dielectric properties of the composite film (CF). TENG devices are fabricated using phosphor‐loaded CFs as the tribonegative layer, transparent polyvinyl alcohol as the tribopositive layer, and aluminum as the conductive electrode. All the TENGs operate in a contact‐separation mode, and the highest electrical output is attained by optimizing the phosphor filler concentration in the CF. The optimized TENG exhibits excellent stability in long‐term operational tests, under varying harsh ambient temperatures. Indium tin oxide sputtered on both triboelectric films as an electrode and combined with a transparent hard substrate to obtain a fully transparent TENG. A self‐illuminating TENG (SI‐TENG) is fabricated by integrating near‐ultraviolet light‐emitting diodes between two identical TENGs. The SI‐TENG can harvest the mechanical energy available in the surrounding environment and illuminate it as a light source. Additionally, the proposed phosphor‐loaded polymer films can be employed for optical thermometry and mechanical energy harvesting via SI‐TENG on a large scale.

Polyetherimide nanocomposite with enhanced mechanical, thermal and dielectric properties by incorporating synergistically exfoliated‐chemical functionalization induced hexagonal boron nitride nanosheets

AbstractThe present study aims to improve the mechanical, thermal and dielectric properties of polyetherimide (PEI) nanocomposite via simplified method, involving the creation of a nanocomposite using PEI incorporated with exfoliated‐chemical functionalization induced hexagonal boron nitride nanosheets (BNNS). XRD, FTIR and Raman elucidated the chemical structure of functionalized BNNS and indicated the success preparation of functionalized BNNS. Functionalization effectively improved the compatibility of nanocomposites and contributed to the property improvements. Morphological analysis unveiled a compact and dense microstructure within the nanocomposites in correlation with functionalized BNNS. Broad band dielectric spectroscopy revealed excellent dielectric properties of produced PEI nanocomposite. DMA testing verified a noteworthy enhancement in both Tg and storage modulus upon incorporating of BNNS. In summary, this comprehensive investigation highlights the impact of functionalized BNNS on mechanical, thermal and dielectric properties of developed PEI dielectric nanocomposite and is expected to expand the application of PEI in the field of high‐temperature energy storage.Highlights Polyetherimide (PEI) was used as polymer matrix and boron nitride derivatives as dielectric fillers to prepare PEI dielectric nanocomposite. Due to the influences of dielectric properties by interface polarization effect and the local distribution of electric field of the fillers in PEI matrix, the dielectric constant, breakdown strength and energy storage density of PEI nanocomposites were obviously improved compared with pure PEI. The effects of interfacial interactions between PBNNS and PEI contributes to the uniform dispersion and comprehensive property improvements of PEI dielectric nanocomposites. This work presents a systematic investigation into the fabrication of PEI/BNNS nanocomposite using a one‐step solution blending method, inspiring the research and development of PEI in the energy storage applications areas in the future.

Engineering digital light processing ceramic composites for wide-range flexible sensing arrays

Flexible ceramic composites are promising candidates in capacitive pressure sensing applications. However, the fabrication of complex composite structures typically involves costly and time-consuming processes such as lithography or mold utilization. Digital light processing (DLP)-based 3D printing offers a layer-by-layer approach via photopolymerization, facilitating rapid prototyping of various ceramic composite structures in a single-step synthesis process. This study presents the successful implementation of a flexible ceramic composite based on the highly dielectric ceramic BaTiO3 and conductive MWCNT fillers by employing DLP 3D printing to create an hourglass-shaped stress concentration structure, aiming at enhancing flexible capacitive sensing capabilities. Blending commercial flexible resin with 4-acryloyl morpholine monomers yields a photocurable resin formulation with appropriate mechanical flexibility, photocurability, and optimal suspension viscosity suitable for DLP 3D printing. Furthermore, the proposed 3D-printed sensor arrays comprising hourglass-shaped unit cells demonstrate improved linear sensitivity across a broad pressure range owing to efficient stress concentration effects in a symmetric geometry, as corroborated by both finite element methods and experiments. DLP 3D printing, combined with tailored resin formulations and optimized ceramic and conductive filler contents, enables the rapid prototyping of diverse sensor structures with significantly enhanced sensitivity, highlighting the versatility of this approach for a wide range of applications.

Polyimide nanocomposites for high‐temperature capacitive energy storage applications by incorporating functional graphene oxide nanosheets: Design, preparation, and mechanism

AbstractHerein, graphene oxide (GO) and its derivative, reduced GO (rGO) and p‐phenylenediamine (PPD) functionalized GO (GO‐g‐PPD) were first synthesized and selected as dielectric fillers, and then GO/polyimide (PI), rGO/PI, and GO‐g‐PPD/PI dielectric nanocomposites were fabricated through in situ polymerization‐composition strategy. Fourier transform infrared, Ram, and x‐ray diffraction analysis confirmed the success synthesis of rGO and GO‐g‐PPD dielectric fillers. The mechanical properties showed that GO‐g‐PPD/PI nanocomposites exhibited the highest tensile strength and elasticity modulus. TGA analysis revealed that the enhancement of thermal stability by addition of dielectric fillers. The dielectric constant of 2.5 wt.% GO‐g‐PPD/PI nanocomposites reached 25.05, which was 8.55 times that of pure PI (2.93). Energy storage performance tests showed that the energy storage density of GO‐g‐PPD/PI containing 2 wt.% filler reached 0.77 J/cm3, which was 71% higher than pure PI. These findings underscore the potential of GO derivative as a cost‐effective reinforcement for PI dielectric nanocomposites for high‐temperature capacitive energy storage applications.

Identifying ultrathin dielectric nanosheets induced interface polarization for high-performance solid-state lithium metal batteries

Solid-state lithium metal batteries (SSLMBs) with polymer electrolytes are promising due to enhanced safety and high energy density, but the low ionic conductivity of polymer electrolytes and the unstable interface of lithium metal anode hinder the development of SSLMBs. Herein, we propose a unique strategy to address these challenges by coupling ultrathin high-dielectricity Ca2Nb3O10 (CNO) nanosheets with PEO-based electrolyte. The interfacial polarization originating from the distortion of NbO6 octahedra along the vertical direction of CNO nanosheets is maximized and so the interaction between CNO and LiTFSI, which greatly supports the dissociation of LiTFSI and improves the ionic conductivity (2.0 × 10−4 S cm−1) of the composite polymer electrolyte, compared to that without CNO. The optimized interfacial polarization effect is thoroughly demonstrated by theoretical calculation and experimental results. Moreover, due to a homogeneous, robust and LiF-rich solid electrolyte interphase film with promoted Li ion transport being formed at the lithium metal interface, the superior cycling stability (90 % capacity retention after 440 cycles at 0.5 C) and rate capability for LFP||Li full batteries are achieved. This design of composite polymer electrolyte with ultrathin dielectric nanosheet fillers demonstrates a new approach to the development of high-performance polymer electrolytes for SSLMBs.

High dielectric performance and thermal conductivity dielectric composite film via vertical alignment of hybrid BaTiO3 nanofibers

The arrangement of anisotropic dielectric fillers in polymer matrix can lead to a significant enhancement of dielectric properties along a specific direction, enabling the rapid development of integrated circuits and high-performance microelectronic devices. In this work, magnetic barium titanate nanofibers/polyimide composite films (mBT NFs/PI) with vertically oriented structures were constructed with the assistant of magnetic field. The dielectric constant was significantly increased from 20.8 to 39.1 at a filler content of 30 wt%, as compared to the randomly aligned films. However, the breakdown strength was affected. Addressing this issue, an optimized core-shell structure was fabricated by introducing insulated and thermo-conductive boron nitride (BN) “shell” on the surface of mBT NFs by coaxial electrospinning. The obtained mBT@BN/PI nanocomposite exhibits improved thermal conductivity and breakdown strength, while maintaining a high dielectric constant. This work highlights an effective strategy to achieve excellent dielectric properties and thermal conductivity for high-temperature dielectric capacitor materials.

Lightweight polypropylene/BaTiO3 composite foams with tunable dielectric constant

Lightweight dielectric foam materials with tunable dielectric constant of 2–1 have broad application prospects in the field of Luneburg lens. Expandable polystyrene (EPS) foam is commonly used for fabricating discrete dielectric layers of Luneburg lens, while its temperature resistance and mechanical properties are poor. EPS foam with dielectric constant of >1.5 is also difficult to prepare because of its low expansion ratio. In this work, choosing polypropylene (PP) with better temperature resistance and mechanical properties as polymer matrix, PP/BaTiO3 composite foams are fabricated by subcritical CO2 batch foaming and steam-chest molding. Through the dual regulation of expansion ratio and mold-opening distance, the dielectric constant of PP/BaTiO3 foams can be tunable from ∼1.19 to ∼1.91, with the density increasing from ∼0.14 to ∼0.59 g/cm3. Compared with EPS foams, PP/BaTiO3 foams have lower density under the similar dielectric constant, indicating the weight reduction of polymer dielectric foam materials by introducing high dielectric fillers.

Effect of fillers on the piezocapacitive behaviour of silicone rubber particulate composites

Robotics and fluid dynamics applications have created demand for development of electronic skins with embedded pressure sensors. These applications require simple and low-cost fabrication processes with large area deployment. Both structured and unstructured material approaches to sensor development have been followed. Among the various sensing mechanisms, piezo capacitive transduction is superior. This paper reports the influence of fillers on the piezo capacitive characteristics of unstructured solid silicone rubber composites. Dielectric, conductive and conductive-dielectric fillers were incorporated into solid silicone rubber and fabricated using high temperature compression moulding to form dielectric-dielectric, conductive-dielectric and conductive-dielectric dielectric composites. The results reveal that piezo capacitive sensitivity varies with filler type, filler loading, curing agent loading, mixing time and curing temperature. The experiments reveal improved normalized capacitance with pressure characteristics of linearity and sensitivity of 3.9 × 10−3 (kPa)−1 in the 0–20 kPa range of pressure. These composites are thus candidate materials for flexible pressure sensing applications.

Low-k nano-dielectrics facilitate electric-field induced phase transition in high-k ferroelectric polymers for sustainable electrocaloric refrigeration

Ferroelectric polymer-based electrocaloric effect may lead to sustainable heat pumps and refrigeration owing to the large electrocaloric-induced entropy changes, flexible, lightweight and zero-global warming potential. Herein, low-k nanodiamonds are served as extrinsic dielectric fillers to fabricate polymeric nanocomposites for electrocaloric refrigeration. As low-k nanofillers are naturally polar-inactive, hence they have been widely applied for consolidate electrical stability in dielectrics. Interestingly, we observe that the nanodiamonds markedly enhances the electrocaloric effect in relaxor ferroelectrics. Compared with their high-k counterparts that have been extensively studied in the field of electrocaloric nanocomposites, the nanodiamonds introduces the highest volumetric electrocaloric enhancement (~23%/vol%). The resulting polymeric nanocomposite exhibits concurrently improved electrocaloric effect (160%), thermal conductivity (175%) and electrical stability (125%), which allow a fluid-solid coupling-based electrocaloric refrigerator to exhibit an improved coefficient of performance from 0.8 to 5.3 (660%) while maintaining high cooling power (over 240 W) at a temperature span of 10 K.

Largely enhanced energy harvesting performances of DEGs by constructing all-organic dielectric composites with a soft and deformable filler

This study presents high-performance all-organic DE composites for DEGs by designing a soft dielectric filler with exceptional deformability under stretching.

Tuning dielectric and electromagnetic absorption properties of SiC fiber by in-situ grown polycrystalline carbon nanowires

Silicon carbide fiber (SiCf) has a promising potential to develop structural electromagnetic wave (EMW) absorption materials. Tuning dielectric properties of SiCf is necessary to obtain excellent EMW absorption performances, which is always realized by the introduction of extra dielectric loss phases. Herein, in-situ grown polycrystalline carbon nanowires (CNW) as novel dielectric fillers, possessing moderate conductivity as well as efficient loss ability, were used to improve the EMW absorption performance of SiCf. When the content of CNW is suited, CNW can interconnect with each other and form a multiporous network on the surface of SiCf. Such a unique network makes a great contribution to good impedance matching as well as strong conductivity loss and polarization loss, which endows SiCf with an effective absorption broadband (EAB) of 4.14 GHz at a thickness of 3.0 mm, demonstrating superior EMW absorption performance than most previously reported SiCf/carbon hybrids.

Construction of sandwich‐layered polyimide hybrid films containing double core–shell structured fillers for high energy storage density

AbstractThe inherent low dielectric constant of polyimide (PI) dielectrics restricts their applications to become a component of high energy density film capacitors. In this work, double core–shell structured barium titanate@magnesium oxide@polydopamine (BaTiO3@MgO@PDA) nanoparticles were synthesized successfully and utilized as high dielectric constant functional fillers for PIs, in which the insulating MgO layer meliorated dielectric constant difference between BaTiO3 and PI matrix, and the organic PDA layer improved the compatibility between the inorganic fillers and PI matrices. Then, a series of sandwich‐structured PI‐based hybrid films was prepared through a layer‐by‐layer solution casting method. The middle layer of pure PI with excellent insulating properties effectively suppressed charge injection. With the combination of sandwich structure and the BaTiO3@MgO@PDA nanoparticles, the PI hybrid film containing 15 wt% fillers in the outer layers achieved the maximum breakdown strength of 425.68 kV/mm and the maximum energy density of 5.132 J/cm3, which was 68.3% and 413% higher than those of pure PI film, respectively, meanwhile maintained a low dielectric loss value of 0.0083 at 1 kHz. The introduction of BaTiO3@MgO@PDA enhanced the interfacial polarization due to the high barrier energy between adjacent layers preventing the transfer of electrons and weakening the leakage current in the sandwich‐structured composite film. This work demonstrates that an appropriate combination of high dielectric hybrid fillers and multilayer structure can effectively increase the energy storage density of PI substrate for high‐temperature energy storage applications.Highlights The double core–shell structured BaTiO3@MgO@PDA was synthesized successfully. The sandwich‐structured hybrid films were prepared by layer‐by‐layer method. The energy density of hybrid films reached a high value of 5.132 J/cm3.

Multi-functional piezoelectric nanogenerator based on relaxor ferroelectric materials (BSTO) and conductive fillers (MWCNTs) for self-powered memristor and optoelectronic devices

Nowadays self-charging memristors and photodetectors open the path for future research into energy-autonomous electronics which hold the promise of enabling exceptionally efficient applications in memory storage, small portable electronics, neuromorphic computing, and optoelectronics devices. Hence, in the recent era, much research work has been focused on the development of nanogenerators for technological applications. In this regard, the main aim of the present study is to develop a multi-functional piezoelectric nanogenerator based on relaxor ferroelectric materials having three-phase MWCNTs/BSTO/PVDF nanocomposites. BSTO and CNT fillers promote >80 % electroactive phase nucleation in PVDF, making it appropriate for piezoelectric energy harvesting devices. Incorporating conductive fillers (CNTs) and dielectric fillers (BSTO) into the PVDF matrix enhances the piezoelectric nanogenerator's dielectric, ferroelectric, and output performance. PENG based on an optimized BSTO-CNTs-PVDF composite (with 20 % BSTO and 0.20 % CNTs loading) produced an output power of 31.5 µW with a high open-circuit voltage of 42 V and a short-circuit current of 9 µA, it demonstrates enough capability to power up small portable electronic devices. This work can also be used for a realistic technique for generating self-powered memristors and photodetectors for extremely efficient memristive neural networks and optoelectronics devices. Demonstration of power generation of the prepared device by different activities is demonstrated.