High-temperature Capacitor Applications Research Articles

Broad temperature range with stable permittivity and low dielectric loss in (1–2x)Na0.5Bi0.5TiO3-xNaNbO3-xGdFeO3 system

High-temperature capacitors have garnered increasing attention in current research due to the inability of commercially available capacitors to meet the evolving industry demands. In this study, a Na0.5Bi0.5TiO3 based ternary system, denoted as [(1–2x)(Na0.5Bi0.5TiO3) -x(NaNbO3) -x(GdFeO3): x=0.01–0.09], was synthesised through solid-state reaction route. The influence of NaNbO3 and GdFeO3 on phase structure, dielectric, and ferroelectric properties are investigated. A fall of polar R3c phase % from X-ray refinement studies, diminishing macroscopic polarization, increasing breakdown strength, and flattening of temperature-dependent dielectric permittivity curves are perceived with the increase of substituent concentration. Temperature stable permittivity of (1–2x)(Na0.5Bi0.5TiO3) -x(NaNbO3) -x(GdFeO3) calculated ε'r/ε'r [250℃] at 1, 10, 100, 500 kHz with 10 % tolerance. Remarkably, (Δε′/ε′250°C ≤ ± 10 %) with x = 0.07 and 0.09 showed stable permittivity in the wide temperature range of (30°C to 600°C) at 500 kHz and a minimal dielectric loss (tan δ ≤ 0.01) measured at 250°C makes it a promising candidate for high-temperature dielectric capacitor applications.

Doublet doped titanate ferroelectric system for capacitors and NTC thermistor applications

A simple negative temperature coefficient (NTC) thermistor Ba0.85Sr0.15Ti0.85Zr0.15O3 system is elaborated using a conventional solid-state reaction route. The structural analysis confirms that the elaborated pseudo-cubic system, which is indexed in the P4mm space group, exhibits one single phase. The dielectric properties and the electrical resistivity data are investigated over a large temperature range from 413 K to 673 K. In this temperature interval, the Steinhart–Hart equations are employed to confirm that Ba0.85Sr0.15Ti0.85Zr0.15O3 is a promising system for sensor application. Accordingly, the thermistor constant (β=10154 K), the sensitivity factor (-5.5 %/K≤α≤-2 %/K), the activation energy (Ea=0.875 eV), and the stability factor (SF=2.27) parameters are calculated to approve that Ba0.85Sr0.15Ti0.85Zr0.15O3 exhibits an NTC-thermistor behavior. The temperature dependence of the electrical resistivity confirms that Ba0.85Sr0.15Ti0.85Zr0.15O3 reveals a semiconductor behavior. The dielectric investigation shows that Ba0.85Sr0.15Ti0.85Zr0.15O3 exhibits a motivating dielectric properties (elevated dielectric constant value (105<ε’<106) and low dielectric losses (mostly < 0.007) with almost frequency independence between 20 Hz to 500 kHz). The colossal dielectric response of Ba0.85Sr0.15Ti0.85Zr0.15O3 is attributed to the internal barrier layer capacitor (IBLC) and the surface barrier layer capacitor (SBLC) effects. Such response suggests the suitability of Ba0.85Sr0.15Ti0.85Zr0.15O3 ceramic for high temperature capacitor applications.

High-temperature dielectric nanocomposite film of 2D Bi4Ti3O12/ABS with excellent energy storage performance

The utilization of high-temperature dielectrics in capacitive energy storage is of great significance in contemporary electronic systems. Nevertheless, the thermal stability of most emerging polymers exhibits a significant decline in their energy storage capacity as temperatures rise. In this study, a unique type of 2D Bi4Ti3O12 nanofillers was synthesized in order to improve the breakdown strength. A nanocomposite consisting of Bi4Ti3O12/poly(acrylonitrile-butadiene-styrene) (ABS) was synthesized with the aim of attaining enhanced dielectric characteristics and energy storage density under elevated temperatures. The Bi4Ti3O12/ABS nanocomposites exhibited notable temperature stability in relation to their dielectric and energy storage capabilities across a temperature range spanning from room temperature to 120 °C. Ultrahigh discharged energy density (Ue) of 12.44 J/cm3 for 3 wt%- Bi4Ti3O12/ABS nanocomposites and high efficiency of 87 % under 550 MV/m were achieved at room temperature. An excellent Ue of 9.12 J/cm3 and high efficiency of 86.2 % for 3 wt%- Bi4Ti3O12/ABS nanocomposites were also observed in 3 wt%- Bi4Ti3O12/ABS nanocomposites under 450 MV/m at 120 °C, which was 117 % and 114 % of ABS films. These capacitive performances could match or be higher than previously reported values for high-temperature capacitor applications.

Polyphenylene Oxide Film Sandwiched between SiO2 Layers for High-Temperature Dielectric Energy Storage.

The commercial capacitor using dielectric biaxially oriented polypropylene (BOPP) can work effectively only at low temperatures (less than 105 °C). Polyphenylene oxide (PPO), with better heat resistance and a higher dielectric constant, is promising for capacitors operating at elevated temperatures, but its charge-discharge efficiency (η) degrades greatly under high fields at 125 °C. Here, SiO2 layers are magnetron sputtered on both sides of the PPO film, forming a composite material of SiO2/PPO/SiO2. Due to the wide bandgap and high Young's modulus of SiO2, the breakdown strength (Eb) of this composite material reaches 552 MV/m at 125 °C (PPO: 534 MV/m), and the discharged energy density (Ue) under Eb improves to 3.5 J/cm3 (PPO: 2.5 J/cm3), with a significantly enhanced η of 89% (PPO: 70%). Furthermore, SiO2/PPO/SiO2 can discharge a Ue of 0.45 J/cm3 with an η of 97% at 125 °C under 200 MV/m (working condition in hybrid electric vehicles) for 20,000 cycles, and this value is higher than the energy density (∼0.39 J/cm3 under 200 MV/m) of BOPP at room temperature. Interestingly, the metalized SiO2/PPO/SiO2 film exhibits valuable self-healing behavior. These results make PPO-based dielectrics promising for high-temperature capacitor applications.

All-organic sandwich structured polymer dielectrics with polyimide and PVDF for high temperature capacitor application

All-organic sandwich structured polymer dielectrics with polyimide and PVDF for high temperature capacitor application

Dielectric temperature stability and energy storage performance of NBT-based lead-free ceramics for Y9P capacitors

In this work, novel (1 [Formula: see text])(0.75Na[Formula: see text]Bi[Formula: see text]TiO3)-0.25Sr(Zr[Formula: see text]Sn[Formula: see text]Hf[Formula: see text]Ti[Formula: see text]Nb[Formula: see text])O3-[Formula: see text]NaNbO3 (NBT-SZSHTN-[Formula: see text]NN, [Formula: see text] = 0.1, 0.15, 0.2, 0.25) ceramics were fabricated. The influence of co-doping of NN and high entropy perovskite oxide (SZSHTN) on the phase structure, microstructure and dielectric properties of NBT-based lead-free ceramics was investigated. Dense microstructure with a grain size of [Formula: see text]5 [Formula: see text]m is observed. When [Formula: see text] = 0.25, a wide dielectric temperature stable range of −35.4–224.3[Formula: see text]C with a low temperature coefficient of capacitance of [Formula: see text] 10% is achieved, fulfilling the industry standard of Y9P specification. Furthermore, excellent energy storage performance with recoverable energy density of 2.4 J/cm3, discharge efficiency of 71%, power density of 25.495 MW/cm3 and discharge rate [Formula: see text] 200 ns are simultaneously obtained, which shows great potential for high temperature capacitor applications.

Improved dielectric and AC conductivity properties of P(VDF-TrFE)-Nafion blends for high-temperature flexible capacitor applications

The free-standing poly (vinylidene fluoride-trifluoroethylene) [P(VDF-TrFe)] and P(VDF-TrFe)-Nafion blended films were fabricated using the casting method. The XRD and FTIR confirmed the electro-active β-phase of P(VDF-TrFe). The morphological changes were studied through SEM analysis of the blends. The dielectric and ac conductivity measurements were carried out as a function of temperature from 30 °C to 130 °C in the frequency range of 100 Hz - 1 MHz. The dielectric constant reveled a ferroelectric to paraelectric transition in all the samples with a decrease in the transition temperature of the blends. The temperature-dependent ac conductivity and power law analysis demonstrated the presence of a correlated barrier hoping mechanism with a change in the motional behavior in the blends. The blended films exhibited low dielectric loss and more stable dielecric properties with temperature in comparison to P(VDF-TrFe). These films demonstrated the potential to be used in high-temperature flexible capacitor applications.

Polyimide-Based Composite Films with Largely Enhanced Energy Storage Performances toward High-Temperature Electrostatic Capacitor Applications

Polyimide-Based Composite Films with Largely Enhanced Energy Storage Performances toward High-Temperature Electrostatic Capacitor Applications

NaNbO3 modified BiScO3-BaTiO3 dielectrics for high-temperature energy storage applications

Among the lead-free compositions identified as potential capacitor materials, BiScO3-BaTiO3 (BS-BT) relaxor dielectrics exhibit good energy storage performance. In this research, 0.4BS-0.6BT is considered as the parent composition, with NaNbO3 (NN) addition intended to substitute the A and B site cations. The NN modified BS-BT ceramics exhibit excellent temperature stability in terms of their dielectric properties, with the room-temperature dielectric constant on the order of 500–1 000 and variation less than 10% up to 400 °C. In addition, NN has a high band-gap energy leading to increased breakdown strength and energy storage properties in modified compositions. The highest breakdown strength was achieved for 0.4BS-0.55BT-0.05NN, being on the order of 430 kV/cm, and a high energy density of 4.6 J/cm3 with high energy efficiency of 90% was simultaneously achieved. Of particular importance is that the variation of the energy density was below 5% due to the temperature-insensitive dielectric constant, while ∼90% energy efficiency was retained over the temperature range of 25–160 °C. The improved temperature stability with NN addition makes this composition promising for high temperature capacitor and dielectric energy storage applications.

2D MoS2 Nanosheet‐Based Polyimide Nanocomposite with High Energy Density for High Temperature Capacitor Applications

Front Cover: In article number 2100079 by Kailiang Ren and co-workers, a MoS2-g-PMMA/PI (MPP, PI is polyimide) nanocomposite consisting of a thin layer of poly(methyl methacrylate) coated 2D MoS2 nanosheets and PI is reported. The energy density of MPP-3% nanocomposite (3% MoS2) reaches 8.6 J cm−3. Furthermore, the highest energy density of MoS2-g-PMMA/PI reaches 3.92 J cm−3 at 150 °C, which is 47.9% higher than that of the PI film.

2D MoS2 Nanosheet‐Based Polyimide Nanocomposite with High Energy Density for High Temperature Capacitor Applications

AbstractWith the development of electrical vehicles and power electronics, the demand for high‐temperature energy storage capacitors with high energy density has grown rapidly. In this investigation, 2D MoS2 nanosheets are coated with a thin layer of poly(methyl methacrylate) and then mixed with polyimide (PI) solution to fabricate nanocomposites. The dielectric constant of MoS2‐g‐PMMA/PI (MPP‐3%) reaches 4.2, which is 20% higher than that of a pristine PI film. The energy density of the MPP‐3% nanocomposite reaches 8.6 J cm−3, which is 40% higher than the highest energy density of a pristine PI film. In addition, the electric breakdown field of the MPP‐3% composite is 50% higher than that of the MoS2/PI nanocomposite without a surface coating. Furthermore, it is found that the highest energy density of MoS2‐g‐PMMA/PI reaches 3.92 J cm−3, which is 47.9% higher than that of the PI film at 150 °C. The charge–discharge efficiency of the nanocomposite film reaches 61.7% at 150 °C. This result is much higher than the previously reported research results for high‐temperature capacitor applications. The MoS2‐g‐PMMA/PI‐based nanocomposite shows great promise for use in high‐temperature capacitor applications.

Dielectric and piezoelectric properties of lead-free Na0.5Bi0.5TiO3-SrTiO3-BiFeO3 ternary system

This work focuses on the synthesis and characterization of a Pb-free (0.8-x)Na0.5Bi0.5TiO3-0.2SrTiO3-xBiFeO3, 0.00 ≤ x ≤ 0.10 perovskite. The ceramics exhibit significant improvement in some of the key parameters like Tc, dielectric constant, temperature stability, TCε values, etc. XRD patterns suggest 100% perovskite structure (Pseudocubic phase) without any trace of secondary phases. The temperature-dependent dielectric constant of doped ceramics exhibits peculiar response particularly at lower frequencies with εr increasing drastically to extraordinarily large values (˃ 50,000 at 1 kHz, and ˃ 12,000 at 10 kHz). Such an abnormal behavior probably arises due to the interfacial polarization caused by the formation of defect dipoles. Further, successive dielectric anomalies appeared around 200–250 °C and 350–450 °C in the BFO doped samples giving rise to temperature-insensitive dielectric constant over a broad temperature span. The composition (x = 0.05) showed a permittivity of ~4000 at 100 kHz at 250 °C with a normalized permittivity Δε/ε250 varying not more than± 15% from 200 °C to beyond 500 °C. In addition, the same composition yields a TCε value as low as −194 ppm/°C which is promising from the application point of view. Analysis of P-E, J-E and S-E loops predict a probable destabilization of the ferroelectric phase by introduction of relaxor state with the incorporation of BFO in the complex perovskite solid solution. Based on the current results, the NBT-ST-BFO ceramics can be designed to minimize loss via compositional engineering for high-temperature capacitor applications.

Fabrication of bismuth silicate Bi2SiO5 ceramics as a potential high-temperature dielectric material

Bismuth silicate Bi2SiO5 (BSO) is known as an interesting new type of ferroelectric oxide; however, bulk ceramics of BSO have never been obtained because it easily decomposes at high temperature. In this study, we fabricated BSO ceramics for the first time using a sol–gel technique and investigated their potential as a dielectric material for high-temperature capacitor applications. A precursor powder was prepared by a sol–gel synthesis route using tetraethyl orthosilicate and bismuth nitrate pentahydrate as raw materials and then sintered under a small uniaxial pressure of 5 MPa with an addition of CH3COOLi as a sintering aid. A BSO ceramic with the highest relative density of 88.5% was obtained at a very low sintering temperature of 620 °C with preventing significant thermal decomposition. A crystal structure analysis revealed that the obtained BSO ceramic belongs to the ferroelectric monoclinic phase. The dielectric permittivity of the ceramic showed a superior temperature stability (± 5%) at temperatures up to 200 °C, followed by a sharp peak attributed to the ferroelectric–paraelectric phase transition at around 390 °C. The BSO ceramic also showed slim and pinched polarization hysteresis loops due to the random grain orientation and domain wall clamping, leading to a high energy storage efficiency over 75% at temperatures up to 100 °C.

Increased Energy-Storage Density and Superior Electric Field and Thermally Stable Energy Efficiency of Aerosol-Deposited Relaxor (Pb0.89La0.11)(Zr0.70Ti0.30)O3 Films

(Pb0.89La0.11)(Zr0.70Ti0.30)O3 (PLZT 11/70/30) relaxor ferroelectric (RFE) films were fabricated on Pt/Si substrates by aerosol deposition, which not only enabled the deposition of a film at room temperature but also increased the dielectric breakdown strength. Perovskite phase and microstructural analyses were carried out by x-ray diffraction and scanning electron microscopy techniques. A PLZT 11/70/30 RFE AD film annealed at 550 °C exhibited the best dielectric properties (er ~ 1090, tanδ ~ 0.028) and typical relaxor-type slim polarization–electric field (P–E) hysteresis loop with relatively low remanent polarization (Pr ~ 6.81 µC/cm2) and coercive field (Ec ~ 118 kV/cm) even at a high applied electric field (~ 2500 kV/cm). These superior properties were achieved due to high phase purity, low defect densities, and well-tuned grain sizes of an annealed PLZT 11/70/30 RFE AD film. The PLZT 11/70/30 RFE AD film exhibited a high energy-storage density (Wrec ~ 44 J/cm3) which is attributed to the high dielectric breakdown strength, low hysteresis loss (Wloss ~ 10.3 J/cm3), and almost-electric-field-independent efficiency (η ~ 81%, change of ~ 6% with the change from low to high electric fields), calculated using the unipolar P–E hysteresis loop. The excellent temperature stability of the energy efficiency of the PLZT 11/70/30 RFE AD film makes it a promising material for high-temperature energy-storage capacitor applications.

(Bi1/2K1/2)TiO3–SrTiO3 solid-solution ceramics for high-temperature capacitor applications

The relaxor state of (Bi1/2K1/2)TiO3 exhibits promising dielectric properties for high-temperature capacitor applications, but the spontaneous phase transition into the low-temperature ferroelectric state and the excessively high dielectric maximum temperature (Tm) at around 360 °C are the main drawback to this material. In this study we examined solid solutions of (Bi1/2K1/2)TiO3 with SrTiO3 to improve the temperature stability of the dielectric properties. As precursors to fabricate the sold-solution ceramics, fine powders of (Bi1/2K1/2)TiO3 and SrTiO3 were both synthesized by the hydrothermal method. Dense (1 − x)(Bi1/2K1/2)TiO3–xSrTiO3 ceramics with x up to 0.5 were then obtained by reaction sintering of the powders. A crystal structure analysis revealed that the average symmetry of the solid-solution ceramics changes from tetragonal to cubic with increasing the SrTiO3 content. Dielectric measurements showed that the incorporation of SrTiO3 into (Bi1/2K1/2)TiO3 stabilizes the relaxor state to shift Tm largely toward lower temperatures. As a result, the sample with x = 0.5 exhibited a temperature-stable dielectric permittivity of 1700 ± 15% over a wide temperature range from room temperature up to 260 °C. The electric-field and temperature dependences of the energy-storage properties of the sample were also investigated.

Phase structure, Raman spectroscopic, microstructure and dielectric properties of (K0.5Na0.5)NbO3–Bi(Li0.5Nb0.5)O3 lead-free ceramics

(1-x)(K0.5Na0.5)NbO3–xBi(Li0.5Nb0.5)O3 [(1-x)KNN–xBLN, 0 ≤ x ≤ 0.02] dielectric ceramics were synthesized by an ordinary sintering technique. The effects of Bi(Li0.5Nb0.5)O3 addition on the phase structure, microstructure and dielectric properties of KNN ceramics were studied. The phase structure of ceramics shifted from the orthorhombic to pseudo-cubic phase structure with increasing the content of Bi(Li0.5Nb0.5)O3. The addition of Bi(Li0.5Nb0.5)O3 depressed the transition temperature of the orthogonal and tetragonal phases, which is a benefit to the thermal stability of KNN ceramics. Especially, as x = 0.01, the ceramics have a high relative permittivity er (~ 1557), low dielectric loss tanδ (< 2.4%) and good thermal stability Δe/e150°C (≤ ± 10%) from 150 °C to 365 °C. Especially, when x = 0.005, the piezoelectric constant d33 was improved to 133 pC/N. Furthermore, the comprehensive properties of (1-x)KNN–xBLN (0 ≤ x ≤ 0.02) ceramics were enhanced significantly to those of pure KNN ceramics. These results indicate that these ceramics could be considered as the prominent promising candidates for high-temperature capacitor application.

BaTiO3-Based Multilayers with Outstanding Energy Storage Performance for High Temperature Capacitor Applications

With the ultrahigh power density and fast charge–discharge capability, a dielectric capacitor is an important way to meet the fast increase in the demand for an energy storage system such as pulsed...

Synthesis, structural, electrical and magnetic properties of Bi2Fe4-xGaxO9 (0 ≤ x ≤ 1.6)

We investigate the electrical and magnetic properties of the Bi2Fe4-xGaxO9 (0 ≤ x ≤ 1.6) polycrystalline samples synthesized via solid-state reaction technique. Magnetic susceptibility measurements reveal that lightly doped samples (x < 0.8) undergo successive transitions, from high-temperature paramagnetic to antiferromagnetic phase followed by a low-temperature spin-glass state while the samples with heavy doping (x > 0.8) demonstrate paramagnetic to spin-glass (SG) transition. The variation of irreversible temperature obtained from zero field cooling (ZFC) and field cooling (FC) susceptibilities versus measured magnetic field and low-temperature magnetic hysteresis (M-H) loops support the existence of spin-glass phase. The dielectric constant (Ɛr) of Bi2Fe4-xGaxO9 with Ga-dilution reveals a weak-temperature sensitivity in high-temperature range (300 K ≤ T ≤ 550 K), which is advantageous for high temperature capacitor applications and electronic devices.

Polymer multilayer films for high temperature capacitor application

ABSTRACTAdvanced film capacitors require polymers with high thermal stability, high breakdown strength, and low loss for high temperature dielectric applications. To fulfill such requirements, two polymer multilayer film systems were coextruded via the forced assembly technique. High glass transition temperature (T g) polycarbonate (HTPC, Tg = 165 °C) and polysulfone (PSF, Tg = 185 °C) were multilayered with a high dielectric constant polymer, poly(vinylidene fluoride) (PVDF), respectively. The PSF/PVDF system was more thermally stable than the HTPC/PVDF system because of the higher Tg for PSF. At temperatures lower than 170 °C, the HTPC/PVDF system exhibited comparable breakdown strength and hysteresis loss as the PSF/PVDF system. While at temperatures above 170 °C, the PSF/PVDF system exhibited a higher breakdown strength because of the higher Tg of PSF. The electric displacement‐electric field (D‐E) loop behavior of the PSF/PVDF system was studied as a function of temperature. Moreover, a melt‐recrystallization process could further decrease the hysteresis loss for the PSF/PVDF system due to better edge‐on crystal orientation. These results demonstrate that PSF/PVDF and HTPC/PVDF systems are applicable for high temperature film capacitors. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47535.

Temperature-stable dielectric properties from 100 to 375 °C in system (K0.495Na0.495La0.01)(Nb0.997Cu0.0075)O3–Bi(Mg0.5Zr0.5)O3

(1−x)(K0.495Na0.495La0.01)(Nb0.997Cu0.0075)O3-xBi(Mg0.5Zr0.5)O3 (abbreviated as KNLNC-xBMZ) ceramics were designed and prepared. The phase transition, microstructure and electrical properties of the ceramics were investigated. The phase structures of the ceramics transform from orthorhombic to pseudocubic phases and the grain sizes decrease gradually with BMZ content (x) increasing. Additionally, BMZ additions can significantly enhance the dielectric temperature stability and decrease the dielectric loss of ceramics over a relatively broad temperature range. KNLNC-0.02BMZ ceramics exhibit high dielectric permittivity (er = 1542) and small variation (Δer/er150 °C ≤ ± 15%) in dielectric permittivity from 100 to 375 °C, and low dielectric loss (tanδ ≤ 2%) in the temperature range of 100–350 °C, which suggests that this ceramic is a candidate for high-temperature capacitor application.