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Mn‐doped (1‐x)Bi0.5(Na0.8K0.2)0.5TiO3‐xBiAlO3 (Mn:BNKT‐xBA) thin films were synthesized on lanthanum nickelate‐coated silicon substrates by sol‐gel method. The second phase issue of the film can be effectively addressed by optimizing the substrate, and the maximum polarization and breakdown strength can be increased by introducing the proper amount of Al3+, which is advantageous for the film for energy storage. The results have shown that the Mn:BNKT‐0.03BA film exhibits superior ferroelectric properties (with remanent polarization (Pr) of 23.72 µC/cm2, maximum polarization (Pmax) of 75.37 µC/cm2), which could be an excellent candidate for ferroelectric thin film capacitors. [ABSTRACT FROM AUTHOR]

Flexible graphene‐based paper electrodes (FGPEs) are a new class of study and the research on this electrode material has been carried out for approximately ten years. FGPEs have many advantages compared to classical solid electrodes such as being flexible, foldable, adaptable to flexible electronics, being cut, easily shaped, and effective and adjustable modification. In this work, the applicability of FGPEs modified with polyindole (PIN) thin films and zinc oxide nanoparticles (ZnO‐NPs) to energy‐storage systems as a supercapattery design is presented, and especially the limitations of ZnO‐NPs for energy‐storage applications are revealed to inform researchers working for a similar purpose. Capacitance calculations have been performed using both cyclic voltammetry (CV) and galvanostatic charge‐discharge (GCD) experiments. It was observed that the rGO/PIN paper demonstrated almost 30 times more energy‐storage capacity than that of the rGO/PIN/ZnO paper due to the electrochemical instability of ZnO‐NPs on the flexible electrode platform at the applied potential region in 1.0 M HClO4 solution. The rGO/PIN paper with a highly flexible property exhibited an energy density of 74.5 W h cm−2 and a power density of 2258 W cm−2 at a current density of 2.2 mA cm−2, revealing hopeful results for future modular and flexible approaches. [ABSTRACT FROM AUTHOR]

In the last few decades, dielectric capacitors have gotten a lot of attention because they can store more power and charge and discharge very quickly. But it has a low energy-storage density (Wrec), efficiency (η), and temperature stability. By adding Pb(Mg1/3Nb2/3)O3 (PMN) and (Bi0·1Sr0.85)TiO3 (BST) to a nonstoichiometric (Bi0·51Na0.5)TiO3 (BNT) matrix, the goal is to change the phase transition properties and make the material more relaxor ferroelectric (RFE) by lowering the remnant polarization Pr and keeping the maximum polarization Pmax. A viscous polymer process (VPP) is used to improve the electric breakdown strength, which is also a key part of being able to store energy. By working together, ceramics with the formula 0.79[0.85BNT-0.15PMN]-0.21BST (BP-0.21BST) are made. The phase structure has been changed from a rhombohedral phase to a rhombohedral-tetragonal coexisted phase. This is beneficial for RFE properties and gives a Wrec of 6.45 J/cm3 and a η of 90% at 400 kV/cm. Also, the energy-storage property is very temperature stable between 30 and 150 °C. These results show that process optimization and composition design can be used to improve the energy storage properties, and that the dielectric ceramic materials made can be used in high-powder pulse dielectric capacitors.

Bismuth potassium titanate (Bi 1/2 K 1/2)TiO 3 -based relaxor ferroelectrics are promising materials for high-energy-density ceramic capacitors. Herein, we compare the microstructure and energy-storage properties of (Bi 1/2 K 1/2) 0.5 Sr 0.5 TiO 3 (BKST50) ceramics fabricated via two different routes: solid-state and hydrothermal reactions. A BKST50 fine powder composed of well-dispersed cubic nanoparticles was obtained via the hydrothermal reaction, whereas the conventional solid-state reaction resulted in the aggregation of primary particles. The grain size of the ceramics prepared from the hydrothermal powder could be controlled between 273 ± 24 and 936 ± 69 nm while maintaining a relative density of over 95% by simply varying the sintering temperature. On the other hand, ceramics prepared via the solid-state reaction could not be fully densified even at 1200 °C (the highest tested sintering temperature). The hydrothermally derived ceramics withstood higher electric field owing to dense and fine-grained microstructure, leading to a high recoverable energy-storage density of 2.25 J cm−3 at 240 kV cm−1. [ABSTRACT FROM AUTHOR]

Dielectric ceramics with both excellent energy storage and optical transmittance have attracted much attention in recent years. However, the transparent Pb‐free energy‐storage ceramics were rare reported. In this work, we prepared transparent relaxor ferroelectric ceramics (1 − x)Bi0.5Na0.5TiO3–xNaNbO3 (BNT–xNN) by conventional solid‐state reaction method. We find the NN‐doping can enhance the polarization and breakdown strength of BNT by suppressing the grain growth and restrained the reduction of Ti4+ to Ti3+. As a result, a high recoverable energy‐storage density of 5.14 J/cm3 and its energy efficiency of 79.65% are achieved in BNT–0.5NN ceramic at 286 kV/cm. Furthermore, NN‐doping can promote the densification to improve the optical transmittance of BNT, rising from ∼26% (x = 0.2) to ∼32% (x = 0.5) in the visible light region. These characteristics demonstrate the potential application of BNT–xNN as transparent energy‐storage dielectric ceramics. [ABSTRACT FROM AUTHOR]

Because of their possible applications in dielectric energy-storage capacitor devices, (Bi 0.5 Na 0.5)TiO 3 -based (BNT) relaxor ferroelectric (RFE) ceramics are feasible alternatives to lead-containing electroceramics. Good energy-storage performance (ESP), including high recoverable energy density (W rec) and good energy discharge efficiency (η), is required to achieve device miniaturization and long device lifetimes. An advanced method was used to overcome the challenges of A-site ionic disordered RFE in achieving high inducible polarization and low hysteresis, with the former dictating a large W rec and the latter dictating a high η. In this study, an ABO 3 perovskite-structured complex end-member Bi(Mg 2/3 Nb 1/3)O 3 (BMN) was added to a 0.7Bi 0.5 Na 0.4 K 0.1 TiO 3 –0.3Ba 0.5 Sr 0.5 TiO 3 (0.7BNKT–0.3BST) matrix. The differences in the valence states and ionic radii of Mg2+, Ti4+, and Nb5+ increased the local electric field fluctuation, which contributed to the expanded dielectric relaxation properties. The combined substantial prevention of hysteresis and remanent polarization suggests high potential applicability for ESP. Finally, an enhancement in W rec to 4.98 J/cm3 was achieved in 0.595BNKT–0.255BST–0.15BMN with an ultrahigh η of 97.3% in a medium-strength electric field of 300 kV/cm. The ESP also demonstrated good thermostability between 30 and 120 °C. Furthermore, the strategy used in this study to generate RFEs can serve as a guide for future research. [ABSTRACT FROM AUTHOR]

Rare earth tri‐doped precursor glasses (PGs) were prepared by traditional high‐temperature melting method, and NaSr2Nb5O15 transparent glass–ceramic (GC) was obtained by subsequent heat treatment. Results exhibit that the up‐conversion emission intensity of GC is greatly enhanced compared to PG. Benefiting from the multiple emission bands from Ho3+ and Tm3+ and their different temperature dependence, multi‐ratio optical temperature measurement is realized. The ultimate relative sensitivity (Sr‐max) can reach 2.00% K−1 between 298 and 598 K. It provides a possibility for self‐reference temperature measurement. Furthermore, under the actual charging and discharge conditions, the GC heated at 750°C has great energy density (Wd = 1.15 J/cm3@600 kV/cm) and high‐power density (Pd = 290.4 MW/cm3@600 kV/cm) with ultrafast discharge time (<15.8 ns). The previous results indicate that the obtained GC with good multifunctional properties is expected to be applied in the field of photoelectric conversion. [ABSTRACT FROM AUTHOR]

Heterocyclic systems are now considered to be an integral part of material chemistry. Thiophene, selenophene, furan, pyrrole, carbazole, triazine and others are some such examples worth mentioning. 2,4,6‐Tri(thiophen‐2‐yl)‐1,3,5‐triazine is a C3h‐symmetric system with thiophene as the donor unit and s‐triazine as the acceptor unit. This review gives an insight into the advances made in the thienyl‐triazine chemistry over the past two to three decades. The synthetic pathways for arriving at this system and all its important derivatives are provided. The major focus is on the materials synthesized using the thienyl‐triazine system, including star molecules, linear and hyperbranched polymers, porous materials and their diverse applications. This review will play a catalytic role for new dimensions to be explored in thienyl‐triazine chemistry. [ABSTRACT FROM AUTHOR]

Lead-free dielectric ceramics with a high recoverable energy-storage density (W rec) and improved efficiency (η) are crucial for the development of pulse power capacitor devices. Although W rec has been constantly improving, mainly via an increased breakdown electric field strength (E b), a large driving electric field (>500 kV/cm) increases security risks and consequently increases insulating technology costs. In this work, we present a new (Bi 0.5 Na 0.5)TiO 3 (BNT)-based relaxor ferroelectric system, (1− x)(0.75Bi 0.5 Na 0.4 K 0.1 TiO 3 -0.25SrTiO 3)- x Bi(Mg 0.5 Ti 0.5)O 3 (BS- x BMT), with x ranging from 0.05 to 0.20. BMT disrupts both the A- and B-site long-range ferroelectric order of the ABO 3 perovskite-structured BS matrix, induces polar nanoregions, and simultaneously increases W rec and η. Aided by the viscous polymer process, the E b with x = 0.15 increased to 270 kV/cm, and a maximum polarization (P m) of 62 μC/cm2 was attained. A boosted W rec of 4.82 J/cm3 and a high η of 84.9% were simultaneously obtained, together with good temperature stability from 30 to 140 °C. These results show that BNT-based dielectric ceramics with superior energy-storage properties can be obtained under a medium electric field. [ABSTRACT FROM AUTHOR]

Relaxor ferroelectrics have garnered enormous attention for their great application potential in pulsed power energy-storage capacitors, while simultaneously achieving large recoverable energy density (W rec) and high efficiency (η) remains a formidable challenge. Through collaboratively controlling multiscale structure via a combination of composition design and processing improvement, polar nanodomains with multiple local symmetries were engineered in ultrafine grains, enabling significantly reduced polarization hysteresis, delayed saturation polarization, maintained high polarization, and enhanced breakdown strength. As a result, an excellent comprehensive energy-storage performance of W rec ∼11.8 J/cm3 and η ∼88.7 % is achieved in the (Na, K)NbO 3 -based spark-plasma-sintered lead-free ceramics, together with stable charge-discharge properties of power density ∼176.3 MW/cm3, discharge energy density ∼3.2 J/cm3, and discharge time ∼43 ns over a wide temperature range of 20–140 °C. The studied ceramic demonstrates great advantages in advanced capacitive energy-storage applications. • BNZ doping brings highly dynamic polar nanodomains with multiple local symmetries, improving energy storage performance. • Breakdown strength was significantly improved by applying SPS. • Ultrahigh W rec of ∼11.8 J/cm3 and large η of ∼88.7 % were achieved. • Stable discharge energy density of ∼3.2 J/cm3 and time of ∼43 ns were obtained in the 20–140 °C range. [ABSTRACT FROM AUTHOR]

• MoS 2 @NiO synthesized for enhanced electrochemical properties. • Varied MoS 2 concentrations optimized electrochemical performance. • Refined MoS 2 @NiO electrode achieved 419.5 C/g at 1 A/g. • Faradic or diffusion processes dominate charge storage. • Synergistic MoS 2 NiO interaction yields 47.43 Wh/kg. In this investigation, MoS 2 @NiO heterostructures are competently synthesized through a straightforward hydrothermal method to serve as an electrode material with augmented electrochemical capabilities. Variations in the concentration of MoS 2 in the composite material are explored to optimize its performance. Extensive analyses are conducted to evaluate the structural, morphological, and electrochemical attributes of the synthesized material. The most refined MoS 2 @NiO heterostructure-based electrode showcases a notable specific capacity of 419.5 C/g (1048.75 F/g) at 1 A/g, transcending MoS 2 and NiO-based electrodes by 60 % and 45 %, respectively. It is revealed that Faradic or diffusion phenomena predominate in the charge storage mechanisms. Capitalizing on the synergistic interplay between MoS 2 and NiO within the composite material, the supercapacitor with asymmetric configuration i.e. MoS 2 @NiO//graphite-activated carbon (GAC), achieves a commendable energy density of 47.43 Wh/kg at 0.825 kW/kg. Furthermore, the developed device retains approximately 80 % of its specific capacitance and around 85 % of Coulombic efficiency after 5000 cycles at 2 A/g, underscoring its robust cyclic stability. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Heterocyclic systems are now considered to be an integral part of material chemistry. Thiophene, selenophene, furan, pyrrole, carbazole, triazine and others are some such examples worth mentioning. 2,4,6‐Tri(thiophen‐2‐yl)‐1,3,5‐triazine is a C3h‐symmetric system with thiophene as the donor unit and s‐triazine as the acceptor unit. This review gives an insight into the advances made in the thienyl‐triazine chemistry over the past two to three decades. The synthetic pathways for arriving at this system and all its important derivatives are provided. The major focus is on the materials synthesized using the thienyl‐triazine system, including star molecules, linear and hyperbranched polymers, porous materials and their diverse applications. This review will play a catalytic role for new dimensions to be explored in thienyl‐triazine chemistry.

With growing concerns over environmental protection, lead-free dielectric ceramic capacitors are attracting much attention. In this work, a series of novel (1- x) Na 0.5 Bi 0.5 TiO 3 - x Ba 5 LaTi 3 Ta 7 O 30 ((1- x)NBT- x BLTT) dielectric composite ceramics were fabricated by a traditional solid‐state method. All the samples possess a compact microstructure with refined grain morphology with increasing BLTT content, and tend to exhibit a diphase dielectric composite as x reaches up to 0.05. Furthermore, the addition of BLTT enhances the dielectric relaxor behavior of NBT-based ceramics, such that the x = 0.15 composite ceramic exhibits a typical feature of relaxor ferroelectrics. As a result, a high recoverable energy-storage density of W rec ~3.67 J/cm3, an ultrahigh energy-storage efficiency of η ~97.3%, and a high power density of P D ~333 MW/cm3 can be simultaneously obtained in the x = 0.15 relaxor composite ceramic. This study provides an alternative way to design excellent energy-storage performances in NBT-based compositions through constructing dielectric relaxor composites via introducing non-polar tungsten bronze oxides. [ABSTRACT FROM AUTHOR]

Low energy-storage density hinders the miniaturization of energy-storage devices. Therefore, improving the dielectric constant and field strength of dielectric materials has become a research focus for energy storage. In this study, a novel type of transparent AgNbO 3 antiferroelectric ceramic co-doped with Eu3+ and Hf4+ ions was prepared using the traditional solid-phase sintering method. The effects of Eu3+ and Hf4+ additions on the phase, microstructure, transmittance, and energy-storage performance of AgNbO 3 transparent antiferroelectric ceramics were systematically studied. The results show that a few Hf4+ ions doped into the AgNbO 3 matrix do not change the perovskite structure of AgNbO 3. Meanwhile, Eu3+ doping can induce a phase red-shift. This reveals that the co-doping of Eu3+ and Hf4+ can reduce the phase transition temperatures of the monoclinic M 1 -M 2 and M 2 -M 3 phases. The (Ag 0.91 Eu 0.03) (Nb 0.96 Hf 0.05)O 3 ceramic possesses high transparency, with an optical transmittance of 42% at 780 nm, and its energy-storage density and energy efficiency can reach 4.08 J/cm3 and 65.0%, respectively, at an electric field of 320 kV/cm. Furthermore, the as-prepared antiferroelectric sample exhibited satisfactory thermal stability at 20–120 °C. All the aforementioned merits make it a most promising original energy-storage material. [ABSTRACT FROM AUTHOR]

Molecular light‐harvesting capabilities and the production of low‐temperature heat output are essential for flexible self‐heated textiles. An effective strategy to achieve these characteristics is to introduce photoresponsive molecular interactions (photodynamic bonds) to increase the energy storage capacity and optimize the low‐temperature photochromic kinetics. In this study, a series of sulfonic‐grafted azobenzene‐based polymers interacted with different metal ions (PAzo‐M, M = Mg, Ca, Ni, Zn, Cu, and Fe) to optimize the energy level and isomerization kinetics of these polymers is designed and prepared. Photoinduced formation and dissociation of MO dynamic bonds enlarge the energy gap (∆E) between trans and cis isomers for high‐energy storage and favor a high rate of isomerization for low‐temperature heat release. The suitable binding energy and high ∆E enable PAzo‐M to store and release isomerization energy and bond enthalpy even in a low‐temperature (−5 °C) environment. PAzo‐Mg possesses the highest energy storage density of 408.6 J g−1 (113.5 Wh kg−1). A flexible textile coated with PAzo‐Mg can provide a high rise in temperature of 7.7–12.5 °C in a low‐temperature (−5.0 to 5.0 °C) environment by selectively self‐releasing heat indoors and outdoors. The flexible textile provides a new pathway for wearable thermal management devices. [ABSTRACT FROM AUTHOR]

Bi 0.5 Na 0.5 TiO 3 (BNT)-based dielectric ceramics have received a lot of attention due to the increased demand for pulse ceramic capacitors. However, comprehensive study on the relationship between their internal phase structure, dielectric characteristics, and ferroelectric properties is still lacking. The phase evolution and its impact on dielectric and ferroelectric properties of an important BNT-based solid solution, Bi 0.5 Na 0.4 K 0.1 TiO 3 - x SrTiO 3 (x = 0, 0.1, 0.2, 0.3 and 0.4), were investigated systematically in this work using structural, dielectric, and ferroelectric characterization techniques. X-ray diffraction indicated the coexistence of rhombohedral and tetragonal phases. The frequency- and temperature-dielectric characterization was then used to derive the characteristic temperatures T B , T m , T s , and T d , and a phase diagram was developed. Furthermore, the temperature-dependent current against electric field curves and polarization versus electric field loops were used to derive the characteristic temperatures connected to high electric field features. This study not only explains the phase evolution of the Bi 0.5 Na 0.4 K 0.1 TiO 3 - x SrTiO 3 solid solution, but it also correlates microscopic domains and polar nanoregions to macroscopic dielectric and ferroelectric properties. [ABSTRACT FROM AUTHOR]

Co 3 O 4 /Ti 3 C 2 T x MXene nanocomposites have been fabricated by vacuum filtration and hydrothermal-annealing methods, and their electrochemical performance were investigated for energy storage and conversion, systematically. As electrode materials, Co 3 O 4 /Ti 3 C 2 T x MXene nanocomposites in 6 M KOH solution demonstrated the specific capacitance of 240.1 F g−1 at 0.1 A g−1 and the long-term cycle stability. The solid-state asymmetric supercapacitors exhibited an operating potential window of 1.4 V, a specific capacitance of 97.9 F g−1at 0.25 A g−1, an energy density of 95.9 Wh kg−1 at a power density of 630.4 W kg−1, and excellent long-term durability. Furthermore, the connected solid-state asymmetric supercapacitors inseries and parallels presented the promising practical applications. Besides, Co 3 O 4 /Ti 3 C 2 T x nanocomposites displayed outstanding catalytic behaviors for energy-saving H 2 generation by urea and alcohols electrolysis. The electrolyzer in KOH + CH 3 CH 2 OH electrolyte required only 1.33 V potential to deliver the current density of 0.5 A g−1. Especially, the elctrochemical system of H 2 production by The electrolyzer and the powered solid-state asymmetric supercapacitors based on Co 3 O 4 /Ti 3 C 2 T x nanocomposites was constructed, demonstrating outstanding properties of H 2 production. Therefore, this study not only shows enormous potential of Co 3 O 4 /Ti 3 C 2 T x nanocomposites as a portable power supply but also indicates its great opportunities in energy-saving H 2 production in practical applications. The Co 3 O 4 /Ti 3 C 2 T x nanocomposites were successfully synthesized by vacuum filtration and hydrothermal-annealing methods, which demonstrated excellent capacitive properties for energy storage and catalytic behaviors for H 2 production. The constructed electrochemical systems with Co 3 O 4 /Ti 3 C 2 T x nanocomposites//AC solid-state asymmetric supercapacitors and Co 3 O 4 /Ti 3 C 2 T x nanocomposites//Pt electrolyzers displayed the outstanding electrocatalytic behaviors for energy-saving H 2 production. Therefore, the study present enormous potential of Co 3 O 4 /Ti 3 C 2 T x nanocomposites as a portable energy storage in practical applications, but also indicate its great opportunities in energy-saving H 2 production. [Display omitted] • The Co 3 O 4 /Ti 3 C 2 T x nanocomposites were successfully synthesized. • The Co 3 O 4 /Ti 3 C 2 T x nanocomposites//AC supercapacitors exhibited outstanding performances of energy storage. • The Co 3 O 4 /Ti 3 C 2 T x nanocomposites demonstrated good UOR and MOR performances. • The performances of Co 3 O 4 /Ti 3 C 2 T x nanocomposites//AC supercapacitors with different manners were investigated. • The electrochemical systems for energy-saving H 2 production were constructed with Co 3 O 4 /Ti 3 C 2 T x nanocomposites. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three-dimensional Mo-WO 3 and N719/Al-TiO 2 were synthesized. • A multifunctional Mo-WO 3 @N719/Al-TiO 2 was constructed. • Under dual-control, Mo-WO 3 @N719/Al-TiO 2 shows the most excellent performance. Under optical and electrical control, a multifunctional electro-optical dual-control color-changing and energy-storage device not only realizes quick color conversion, but also achieves good storage performance. In this work, Mo doped WO 3 (Mo-WO 3) films were synthesized through one-step hydrothermal method and N719/Al doped TiO 2 (N719/Al-TiO 2) films were synthesized by hydrothermal and dip-dyeing method. Eventually, choosing Mo-WO 3 as cathode and N719/Al-TiO 2 film as anode, a multifunctional electro-optical dual-control Mo-WO 3 @N719/Al-TiO 2 color-changing and energy-storage device was constructed. Under electrical control, the device shows excellent coloration efficiency (73.99 cm2/C), fast color switching rate (coloring/ bleaching time is 3.6 s/1.4 s), obviously improved area capacitance (about 82.6 mF/cm2) and excellent cycle stability. Under optical control, the device also shows shortened response time (coloring/ bleaching is 64.3 s/143.4 s), outstanding coloration efficiency (70.49 cm2/C), better area capacitance (about 58.6 mF/cm2) and excellent photoelectric conversion efficiency (10.56 %). [ABSTRACT FROM AUTHOR]

Abstract Molecular light‐harvesting capabilities and the production of low‐temperature heat output are essential for flexible self‐heated textiles. An effective strategy to achieve these characteristics is to introduce photoresponsive molecular interactions (photodynamic bonds) to increase the energy storage capacity and optimize the low‐temperature photochromic kinetics. In this study, a series of sulfonic‐grafted azobenzene‐based polymers interacted with different metal ions (PAzo‐M, M = Mg, Ca, Ni, Zn, Cu, and Fe) to optimize the energy level and isomerization kinetics of these polymers is designed and prepared. Photoinduced formation and dissociation of MO dynamic bonds enlarge the energy gap (∆E) between trans and cis isomers for high‐energy storage and favor a high rate of isomerization for low‐temperature heat release. The suitable binding energy and high ∆E enable PAzo‐M to store and release isomerization energy and bond enthalpy even in a low‐temperature (−5 °C) environment. PAzo‐Mg possesses the highest energy storage density of 408.6 J g−1 (113.5 Wh kg−1). A flexible textile coated with PAzo‐Mg can provide a high rise in temperature of 7.7–12.5 °C in a low‐temperature (−5.0 to 5.0 °C) environment by selectively self‐releasing heat indoors and outdoors. The flexible textile provides a new pathway for wearable thermal management devices.

An all-inorganic Pb0.99Nb0.02(Zr0.85Sn0.13Ti0.02)0.98O3 (PNZST) antiferroelectric (AFE) thin film was designed to enhance its energy-storage performance by adjusting its orientation. Using a radio frequency (RF) magnetron sputtering technology, 450-nm-PNZST AFE films with (111), (110), and (100) crystal orientations were successfully prepared. All the films showed a dense microstructure and the highly preferred orientations were determined by the orientation of the bottom electrodes. Moreover, the preferred orientation of the AFE thin film had a great influence on the dielectric and energy-storage properties. Meanwhile, the energy storage density of the PNZST AFE thin film with the (100) orientation reached 33.7 J cm-3, which was 43 % higher than that of PNZST AFE thin film with a (111) orientation. All of these results shed light on how the energy-storage performance of PNZST AFE thin films can be enhanced and optimized by adjusting its orientation. This offers a new strategy and innovation, which opens up a route to practical applications in micro-energy-storage systems.

In this study, lead-free zirconium (Zr)-modified Bi 1/2 (Na 0.78 K 0.22) 1/2 TiO 3 (BNKT) ceramics were synthesized by the conventional solid-state reaction method. The co-existence of two phases (tetragonal; P 4 mm and cubic phases; Pm 3 ‾ m) with definite phase fractions were observed for all samples. The lattice parameters were gradually enhanced by the addition of Zr-content in the BNKT ceramics, which strongly support the relaxor-ferroelectric response. All of the samples are well-dense with no noticeable pores detected. Definite grains with clear grain boundaries were observed through SEM analysis. The temperature-dependent (25–200 °C) ferroelectric polarization response of all specimens were studied in detail under the constant applied electric field (60 kV cm-1). Thermally-stable high energy-storage properties (W rec ≈ 0.72 J cm-3, and η ≈ 98%) with an extended operating temperature range (25–200 °C) within ±15% variation was observed for the Zr-modified BNKT composition. The enhancement of energy-storage properties can be attributed to the Zr addition, which increased the phase fraction of cubic crystal structure and assisted the ferroelectric to relaxor-ferroelectric phase transition. This study provides a comprehensive analysis of the energy-storage response of the lead-free ceramics for energy-storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

This investigation delves into the intricacies of controlled oxidation of graphene oxide (GO) and its influence on the electrochemical performance of reduced graphene oxide (rGO) and Manganese Molybdate based composites. Further, through a meticulous manipulation of GO composition, we achieve the hydrothermal synthesis of rGO@MnMoO 4 composites, wherein the most optimized configuration exhibited a remarkable specific capacity of 1356 C/g and 1299 C/g at 10 mV/s and 2 A/g, respectively. This achievement is ascribed to the intricately designed microporous microrod morphology of MnMoO 4 , synergistically coupled with the electrical conductivity enhancement facilitated by rGO, attributed to its abundant conjugated carbon bonds. The results further culminate in the development of an asymmetric supercapacitor (ASC) denoted as rGO@MnMoO 4 // graphite-activated carbon (G-AC), demonstrated altitudinous energy density of 63.5 Wh/kg at power density of 850 W/kg. Notably, this formidable device demonstrated an excellent stability by retaining 97% of specific capacity after 9460 cycles, evincing minimal structural and morphological degradation. [Display omitted] • Impact of oxidation of GO on capacitive performance of rGO@MnMoO 4 is studied. • Influence of GO's composition on energy storage capability of nanocomposite is explored. • Remarkable demonstration of 1356 C/g at 10 mV/s of rGO@MnMoO 4 electrode. • Asymmetric rGO@MnMoO 4 //G-AC device exhibited altitudinous 63.5 Wh/kg at 850 W/kg. [ABSTRACT FROM AUTHOR]

The increasing demand for compact and functional electronics has led to significant rise in research interest in the development of versatile energy storage systems. With this perspective notion, herein, we fabricated electrically conducting polymer-based flexible carbon cloth (CC) electrodes and assessed their electrochemical performance. Briefly, polyaniline nanofibers (Pani-NFs) and polypyrrole nanotubes (PPy-NTs) were synthesized by interfacial polymerization and reactive self-degrade template method, respectively. The physico-chemical properties of the as-synthesized nanostructured conducting polymers were characterized with the help of X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), field emission transmission electron microscope (FETEM) and Raman spectroscopy. The electrochemical performance of the Pani-NFs and PPy-NTs coated flexible CC electrodes was evaluated in 1 M H2SO4 electrolyte with a potential window of −0.2 to 0.8 V versus saturated calomel electrode (SCE). The Pani-NFs and PPy-NTs coated electrodes yielded the maximum areal capacitance of 0.79 and 0.74 F.cm−2, respectively at a constant discharge current density of 10 mA.cm−2, which was determined from the charge-discharge curve during the discharging period. The results demonstrate the potential of the nanostructured conducting polymer-based flexible electrodes for portable and wearable energy storage applications. [ABSTRACT FROM AUTHOR]

The Ba0.985La0.015Ti0.9Sn0.1O3 ceramic has been prepared by a cost-effective solid-state reaction method. Preliminary room-temperature X-ray diffraction indicates that the crystallization of the ceramic is good. Field Emission Scanning Electron Microscopy was used to study the microstructure of ceramic. X-ray photoelectron spectroscopy was used to characterize the oxygen vacancies. Dielectric properties and impedance spectroscopy reflected the characteristic of relaxor-type behavior. Modified Curie–Weiss law was used to evaluate the relaxor behavior. The fitting result of the relaxation parameter λ = 1.4, which verifies their relaxor property. Jonscher's power law was used to analyze the behavior of alternating current conductivity. The Arrhenius law was used to calculate the relaxor activation-energy (Ea) and the conduction activation-energy (Ec). The fitting results show that the Ea and Ec are 1.1 and 1. 13 eV, respectively. These values demonstrate that the high-temperature relaxor behavior was attributed to the double ionized oxygen vacancies. The electric field versus polarization curve reflects the energy-storage property of it. The maximum recoverable energy-storage density is 2.14 J/cm3, and the energy-storage efficiency is 67.65%. [ABSTRACT FROM AUTHOR]

(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 (εr ~ 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. [ABSTRACT FROM AUTHOR]

NaNbO 3 (NN) is considered to be one of the most prospective lead-free antiferroelectric energy storage materials due to the merits of low cost, nontoxicity, and low density. Nevertheless, the electric field-induced ferroelectric phase remains dominant after the removal of the electric field, resulting in large residual polarization, which prevents NN ceramics from obtaining superior energy storage performance. In this work, the relaxor ferroelectric Sr 0 · 7 Bi 0 · 2 TiO 3 (SBT) was chosen to partially replace the NN ceramics, and the introduction of the nanodomain of the relaxor ferroelectric hinders the generation of field-induced ferroelectric phases, allowing the material to combine the large polarization strength of the relaxor ferroelectric with the near-zero residual polarization of the antiferroelectric. Large recoverable energy storage density (4.5 J cm−3) and ultra-high energy storage efficiency (90.3%) were gained in NN-20SBT under an electric field of 288 kV cm−1. Furthermore, superior temperature (25–120 °C) and frequency (1–500 Hz) stabilities were acquired. These performances demonstrate that NN-20SBT ceramics are potential candidates as dielectric materials for high energy storage density pulsed power capacitors. [ABSTRACT FROM AUTHOR]

The suitability of embedding metal atoms (Ca versus Mn) in the pores of C 2 N to be employed as the anode material for metal-ion battery applications is studied using density-functional theory. The effect of single-atom catalyst (SAC) versus dimer-atom catalyst (DAC) on the uptake catalyst capacity is put under focus. Our results show that both metal atoms exhibit very strong interactions with the pyridinic-nitrogen pore and show the ability of the pore to accommodate either a single Ca atom or a dimer of Mn atoms within its membrane-plane. While the theoretical irreducible capacitance in case of SAC Ca catalyst is limited to about 200 mAhg−1, it can exceed this value in case of DAC-Mn catalyst to reach 1110 mAhg−1. Regarding the adsorption, the H 2 molecule exhibits strong physisorption on Ca-catalyst and moderate chemisorption on Mn-catalyst, with an adsorption energy increasing from SAC to DAC cases. The SAC of Mn is found not only concurrent candidate to Ca for energy-storage applications but further promising for platform of reusable hydrogen gas-sensors with very low recovery time (i.e., τ « 1 s). Our findings are in good agreement with the available experimental data and theoretical results. Image 1 • DFT study of hydrogen adsorption on Metal-catalyst embedded (Ca versus Mn) C 2 N at Room Temperature. • Ca has E coh < E bind in C 2 N, thus, is relevant for energy storage but only SAC can be used for irreducible uptake capacity. • Mn SAC & DAC have cohesive energy < binding energy to C 2 N, thus, is concurrent to Ca for MIBs applications. • Mn DAC showed even higher irreversible uptake capacity (1110 mAhg-1) than Ca SAC (200 mAhg−1). • C 2 N:Mn showed potential for reusable magnetic hydrogen gas sensor with high sensor response and low recovery time. [ABSTRACT FROM AUTHOR]

How to overcome fastly and reliably the challenges to foster the lithium-based salts exploitation for latent heat storage technologies? In situ and real time microscopy is used to understand the discrepancies between the theoretical and experimental macroscopic properties of materials via the microscopic mechanisms. The feasibility of this method on the inorganic lithium salts is demonstrated despite their air/moisture-sensitivity and the common belief pretending that LiOH cannot be used for the synthesis of new materials inside the microscope chamber due to its decomposition in dry environment or under vacuum. The deviation source of ~30% from the theoretical energy density of 434 kWh/m3 has been investigated through the case study of Li4Br(OH)3, an uncommon promising phase change material. The hydration/dehydration of the starting materials appears as one of the main parameters, with applied temperature protocols, eliciting the deviation towards different materials from the targeted one of interest, in terms of morphology and properties. This criterion, if not taken into account, could be disastrous for the storage capacity of a unit during its use. This study highlights solutions to avoid these deficiencies. The results consistency at microscale with those obtained at macroscale is also proved despite the different operating conditions

Among the organic dielectrics, polyvinylidene fluoride PVDF-based polymers present the highest level of polarizability with permittivity >35. Nonetheless, their applications in advanced electronics and industrial uses are limited by significant leakage current under high voltage, which is considered the principal cause of device energy consumption and short lifetime. Therefore, the main objective of this paper was to focus on alternative capacitor structure-based polyvinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene (PVDF-TrFE-CTFE) terpolymers to efficiently limit the leakage current and lead to enhanced electrical breakdown with negligible degradation of polarization level. The novel bilayer capacitor was constructed by depositing a thin barrier layer of high polar PVDF-HFP copolymer on the terpolymer via a rapid solution-casting technique. The relationship between leakage current, dielectric strength and conduction mechanisms was investigated. Implementation of such a barrier layer led to a significant reduction (70%) in leakage current and ferroelectric losses (approximately 90%), thus boosting the performance of multilayered material up to 50% of enhanced energy-storage efficiency. Experimental results are very promising, allowing to confirm that combining both terpolymer and copolymer in a hybrid multilayer design makes a possibility to achieve the best compromise in terms of energy efficiency, dielectric properties, and breakdown strength.

The optical constants (complex dielectric function) of CuO and ZnO particles in polyethylene pellets are measured by terahertz time-domain spectroscopy. The determination of the dielectric properties of these materials is of interest for energy-storage applications, for instance. Maxwell-Garnett theory is used to extract the contribution to the frequency-dependent optical constants of the oxide powders. The validity of the assumptions of Maxwell-Garnett theory are experimentally verified and self-consistency of the results of the model confirmed. On this basis, experimental complex permittivity values for isotropic CuO and ZnO oxide powders are reported in the 100 GHz-3 THz range. [ABSTRACT FROM AUTHOR]

Perovskite-type lead-free Bi 0. 5 (Na 0. 8 0 K 0. 2 0 ) 0. 5 (Ti 1 − x Zrx)O3 (BNKT- x Zr) ferroelectric films (with x from 0.00 to 0.05) were synthesized on Pt/Ti/SiO2/Si substrates via chemical solution deposition. The influence of Zr 4 + concentration on the microstructures, ferroelectric and energy-storage properties of the prepared films was investigated in detail. It showed that the BNKT- x Zr films possessed rhombohedral and tetragonal symmetries in morphotropic phase boundary when a small amount of Zr 4 + was added. Ferroelectric and energy-storage properties of the films investigated at an applied electric field of 600 kV/cm were significantly enhanced with appropriate Zr 4 + concentration. The remnant polarization ( P r ), maximum polarization ( P max ) and P max – P r values at x = 0. 0 2 reached the highest values of 18.1 μ C/cm2, 42.0 μ C/cm2 and 24.0 μ C/cm2, respectively. Thanks to the strong enhancement in P max and the large P max – P r value, the highest recoverable energy-storage density gets the value of 4.6 J/cm3 for the 2 mol.% Zr 4 + -doped BNKT film. These obtained results indicate that the appropriate Zr 4 + -doped BNKT films have many application potentials in the advanced capacitors. [ABSTRACT FROM AUTHOR]

The flexible and free‐standing nanocomposite films were fabricated by a simple solution‐casting process using BaTiO3 nanoparticles as fillers and P(VDF‐CTFE) 91/9 mol% as polymer matrix. To obtain good wettability between ceramic and polymer, the coupling agent 3‐Aminopropyltriethoxysilane was used to modify the surface of BaTiO3 fillers. A good compatibility of BaTiO3 and P(VDF‐CTFE) was achieved when a small amount of coupling agent was used for the surface modification of BaTiO3 fillers; therefore, the nanocomposites with a dense and uniform microstructure was obtained. It was experimentally found that both dielectric constant and breakdown strength were increased with a suitable amount of coupling agent due to the good compatibility. A dielectric constant of 51 at 1 kHz was obtained with 30 vol% fillers and 2 wt% coupling agent, which was about four times of that for the pure P(VDF‐CTFE) film. When an appropriate amount of coupling agent was coated on fillers, the energy storage density of the composite system was improved. A maximal discharge energy‐storage density of 3.8 J/cm3 was obtained for the nanocomposite film with 5 vol% of BaTiO3 and 2 wt% coupling agent, which is much higher than that of the composites without coupling agent. [ABSTRACT FROM AUTHOR]

In recent years, intensive research efforts have focused on translating biomass waste into value-added carbon materials broadcasted for their significant role in energy and environmental applications. For the first time, high-performance carbonaceous materials for energy storage applications were developed from the multi-void structure of the boat-fruited shells of Sterculia Foetida (SF). In that view, synthesized mesoporous graphitic activated carbon (g-AC) via the combination of carbonization at various elevating temperatures of 700, 800, and 900 °C, respectively, and alkali activation by KOH, with a high specific surface area of 1040.5 m2 g−1 and a mesopore volume of 0.295 cm3 g−1. In a three-electrode configuration, the improved electrode (SF–K900) exhibited excellent electrochemical behavior, which was observed in an aqueous electrolyte (1 M H 2 SO 4) with a high specific capacitance of 308.6 F/g at a current density of 1 A/g, owing to the interconnected mesopore structures and high surface area of SF-K900. The symmetric supercapacitor (SSC) delivered the specific capacitance of 138 F/g at 1 A/g with a high energy density (ED) of 13.4 Wh/kg at the power density (PD) of 24.12 kW/kg with remarkable cycle stability and supercapacitive retention of 93% over 5000 cycles. Based on the findings, it is possible to develop low-cost active electrode materials for high-rate performance SSC using mesoporous g-AC derived from SF boat-fruited shells. [Display omitted] • Wrinkled mesoporous graphitic carbon sheets were prepared from Sterculia Foetida. • The g-AC was conceived by pyrolysis carbonization and activation via CVD set up. • The graphitic activated carbon-based electrode displayed high specific capacitance. • The fabricated SSCs exhibited a capacitance retention of 93% for 5000 cycles. [ABSTRACT FROM AUTHOR]

[Display omitted] • XRD clearly indicates both MXene and MgCr 2 O 4 peaks within nanocomposite spectra whereas SEM s shows magnesiochromite particles attachment over MXene nanosheets. • Raman and photoluminescent spectra focused on functional groups existence alongwith maximized electron-hole recombination with bandgap value of 1.8 eV measured from UV spectra. • Peak values for C-F, C–H and MgCr 2 O 4 are visible in FTIR spectra within range 940 cm−1, 2880 cm−1 and 505 cm−1. • Increased electrostatic repulsion designed for colloidal solution as measured by Zeta potential possess value of −19.9 mV. • EIS spectra shows maximum electron transfer rate constant value of 4.097 × 10−9 (cms−1) in IM KOH and 2.66 × 10−9 (cms−1) in 0.1 M H 2 SO 4. • Maximum capacitance value of 542.6F/g is measured in 1 M KOH electrolyte solution at 20 mVs−1 showing its applicability as energy storage material in supercapacitors. In this study, we presented a novel approach involving the co-precipitation synthesis of a two-dimensional MXene nanocomposite with spinel magnesiochromite MgCr 2 O 4. The resulting nanocomposite was comprehensively characterized. The synthesized nanomaterial exhibited an average crystallite size of approximately 6.85 nm, and its surface morphology confirmed the presence of agglomerated grains with the elemental composition being confirmed by EDS spectra. Raman spectra provided evidence of prominent molecular vibrations, while photoluminescence spectroscopy revealed significant electron-hole recombination within the nanocomposite, leading to a reduced bandgap as corroborated by UV–Vis spectra. Zeta potential measurements shows minimum value of −19.9 mV comparable to MXene zeta potential value –23 mV indicating maximum stability. Electrochemical impedance spectroscopy (EIS) spectra highlighted a minimal charge-transfer resistance value of 64.99 Ω in a basic electrolyte, resulting electron transfer rate value about 4.097 × 10−9 (S/cm) resulting maximum conduction. Electrode capacitive behavior in both acidic (0.1 M H 2 SO 4) and basic media (1 M KOH) demonstrates the potential of this novel nanocomposite material with the maximum capacitance value of 542.6F/g observed in basic media in comparison to the minimum capacitance value of 454.1F/g in acidic media. From GCD analysis, maximum power density of 271.2 kW/kg with an energy density value of 14.58 kWh/kg is achieved. These findings underscore its applicability in energy storage applications partially in the context of supercapacitors. [ABSTRACT FROM AUTHOR]

In order to enhance the electrochemical efficiency of supercapacitors, novel active electrode materials are being developed. This study provides a unique method to synthesize an integrated structure consisting of a nickel-cobalt metal-organic framework (NiCo-MOF) on functionalized carbon nanofiber (f-CNF) utilizing a single-step solvothermal method. Physicochemical characterization confirmed the successful synthesis of the integrated system of NiCo-MOF@f-CNF. This novel structure has the potential to significantly improve the electrochemical properties of the initially prepared material for use in supercapacitors. The synthesized electrode has a higher specific capacitance/capacity value of 788 F g−1 (315.2 C g−1) at 1 A g−1 and high cycling stability. The developed hybrid device exhibited a promising specific energy of 8.6 Wh kg−1 and a high specific power of 1147 W kg−1, demonstrating potential for practical applications. The current study suggests that the proposed material can be a viable electrode for high-efficiency supercapacitors. • An integrated structure of NiCo-MOF@f-CNF nanocomposite was prepared and used as an efficient electrode in supercapacitors. • Electrical conductivity, mechanical properties, and surface accessibility were enhanced when f-CNF joined NiCo-MOF. • NiCo-MOF@f-CNF hierarchical structure exhibits a specific capacitance of 788 F g−1 at a current density of 1 A g−1. • NiCo-MOF@f-CNF//AC hybrid supercapacitor shows a specific energy of 8.6 Wh kg−1 at a specific power of 1.147 kW kg−1. [ABSTRACT FROM AUTHOR]

The stability of high energy-storage performance dielectric-film capacitors with respect to frequency, temperature, and cycle number is very essential for developing energy-storage devices. Here, the impact of Sm-doping concentration on the structure and energy-storage stability of lead-free Ba(Zr 0.35 Ti 0.65)O 3 (BZT) films have been systematically investigated. The formation of random electric fields, due to the co-occupying heterovalent ions of Sm3+/Ti4+ at the B-sites, serves to enhance the breakdown strength and reduce the polarization reversibility. As a result, an enhanced recoverable energy-storage density of 133.3 J/cm3 and an excellent energy efficiency of 89.4% are simultaneously achieved in 25 mol% Sm-doped BZT films (BZT-Sm25) under an applied electric field of 7.0 MV/cm. In addition, the BZT-Sm25 films also exhibit outstanding energy-storage performance stability over a large frequency-range of 1–1000 Hz, a wide temperature-range of 25 °C–200 °C, and beyond 1010 switching-cycles, even under a high electric field of 6 MV/cm. These achieved results demonstrate that the Sm-doped BZT films are promising candidates for the development of high-performance and environmentally friendly energy-storage devices. • State-phase transition from relaxor to linear-like dielectric behavior with increasing Sm-doping content. • Field-induced linear dielectric–relaxor phase transition is found in 25%Sm-doped BZT films. • Sm-doping effectively reduced the size of polar nanoregions and enhanced breakdown strength. • Excellent U r of 133.3 J/cm3 and high η of 89.4% are achieved in 25%Sm-doped BZT films. [ABSTRACT FROM AUTHOR]

The low breakdown strength of BNT-based dielectric ceramics limits the increase in energy-storage density. In this study, we successfully reduced the sintering temperature of BNT-ST-5AN relaxor ferroelectric ceramics from 1150 to 980 °C by two-phase compounding with nano-SiO 2. Meanwhile, the average grain size of the composite ceramics is also greatly reduced from 4.45 μm to 0.37 μm. Thus, a large recoverable energy-storage density (3.22 J/cm3) is achieved under the ultrahigh breakdown strength (316 kV/cm). Moreover, good temperature (25–150 °C) and frequency (10–200 Hz) stabilities are simultaneously achieved. The excellent energy-storage properties suggest that BNT-ST-based ceramics composited with SiO 2 form a promising low-temperature sintered dielectric material for pulsed power multilayer ceramic capacitors. [ABSTRACT FROM AUTHOR]

A series of (1- x)(Bi 0.5 Na 0.5) 0.94 Ba 0.06 TiO 3 - x BaSnO 3 (BNBT-100 x BSN, x = 0–20) lead-free ceramics were synthesized using a conventional high-temperature solid-state reaction route. The effects of BaSnO 3 on the dielectric, ferroelectric and energy-storage performance of BNBT-BSN were systematically investigated. Temperature dependent permittivity curves indicated the obviously enhanced relaxor ferroelectric property. The introduction of BaSnO 3 reduced the temperature corresponding to the first dielectric anomaly, which facilitated the dielectric temperature stability. △ε'/ε' 150°C varied no more than 15% within the temperature range of up to 338 °C (45–383 °C) for BNBT-15BSN. A slimed P-E loop was obtained with the remnant polarization of 0.4 μC/cm2 for BNBT-15BSN. Moreover, the breakdown field intensity of BNBT-BSN increased effectively from 80 kV/cm to 115 kV/cm. Therefore, an optimum energy-storage performance was obtained in BNBT-15BSN with the energy-storage density of 1.2 J/cm3 whose energy-storage efficiency reached 86.7%. Furthermore, the possible contributions of defect and vacancy to relaxation and conductance mechanism were discussed by studying the impedance and electric modulus. The results above indicated the BNBT-100 x BSN be a promising lead-free candidate for energy-storage capacitors. [ABSTRACT FROM AUTHOR]

Free-standing, flexible, and transparent ceramic-polymer nanocomposite films with a uniform thickness of about 5 μm were fabricated using a simple spin-coating process, in which the polymer solution with a high concentration was used. Ba 0.5 Sr 0.5 TiO 3 (BST) nanoparticles and P(VDF-CTFE) 91/9 mol.% (VC 91) copolymer were used as ceramic filler and polymer matrix, respectively. Microstructures, dielectric properties, and energy-storage performances of the BST-VC 91 nanocomposite films have been investigated. With increasing volume fraction of BST, the dielectric constant increases, while the dielectric loss decreases. A dielectric constant of about 38.4 at 100 Hz associated with a dielectric loss of only about 0.02 was obtained in the nanocomposite film with 40 vol% of BST. It is experimentally found that the temperature dependences and the frequency dispersions of dielectric properties were strongly influenced by the volume fraction of BST, especially at high temperatures. Good temperature stability and small frequency dispersion of dielectric constant can be obtained in the BST-VC 91 nanocomposite films with 40 vol% and 50 vol% of BST, which are also associated with a low dielectric loss. It is concluded that the motion of the polymer chains is the micro-origin of the relaxation process observed at high temperatures. With increasing volume fraction of BST, the dielectric breakdown strength decreases, while the maximal polarization and remnant polarization increase. The maximal charge-energy density and discharge-energy density of about 21.7 J/cm3 and 7.5 J/cm3 are obtained in the BST-VC 91 nanocomposite film with 30 vol% BST under 2500 kV/cm, which are more than 2 times larger than those observed in pure VC 91 film under the same electric field. [ABSTRACT FROM AUTHOR]

Sr x Ba 1- x Nb 2 O 6 ceramics were prepared via the high-temperature solid-state reaction method. Structural, ferroelectric, electrocaloric effect and pyroelectric energy harvesting capabilities of Sr x Ba 1- x Nb 2 O 6 ceramics were reported. The main structural phase of tetragonal tungsten bronze with Sr-doped was detected by X–ray diffraction. It was found that the ferroelectric hysteresis loops became slimmer after the temperature higher than Curie temperature of Sr x Ba 1- x Nb 2 O 6 ceramics, which was a representative feature of relaxor ferroelectric. In addition, we presented the positive peak values of electrocaloric at vicinity of Curie temperature which was affected by the applied electric field for all samples. It is worth noting that the pyroelectric energy harvesting property is the first time investigated by using Olsen cycle for Sr x Ba 1- x Nb 2 O 6 ceramic. The maximum pyroelectric energy harvesting density was 170 kJ m−3 for x = 0.6 in Sr x Ba 1- x Nb 2 O 6 with the temperature range from 293 to 433 K. The experimental results indicated that better pyroelectric energy harvesting property and larger electrocaloric effect of Sr x Ba 1- x Nb 2 O 6 ceramic benefited from the higher Sr/Ba ratio. Finally, energy-storage capacity for Sr x Ba 1- x Nb 2 O 6 ceramic was obtained from the ferroelectric hysteresis loop and the maximum room-temperature energy-storage efficiency was 86.37% with x = 0.6 under 60 kV cm−1. Image 1 • The pyroelectric energy harvesting property was first studied in Sr x Ba 1- x Nb 2 O 6 ceramics. • Positive electrocaloric effect in Sr x Ba 1- x Nb 2 O 6 ceramics were demonstrated. • The maximum energy-storage efficiency is 87.94% for Sr 0.6 Ba 0.4 Nb 2 O 6 ceramics. [ABSTRACT FROM AUTHOR]

In order to solve the problem of narrow color change range for common thermochromic material, the novel thermochromic and energy-storage microcapsules (TCEMs) was designed and synthesized by in-situ polymerization. The TCEMs contained optimizational thermochromic components and phase change materials, and exhibited the dual functional performances of thermochromic and energy-storage. Then, the TCEMs were applied to polyester/cotton blend fabric with waterborne polyurethane by coating process. The growing process, exterior morphology, color change effect, temperature-regulable behavior and thermal activity of the TCEMs and the treated fabrics were investigated. The results demonstrated that both TCEMs and modified fabrics had good energy-storage effect and remarkable thermochromic property. Especially, while surrounding temperature changed from 15 °C to 45 °C, the colors of TCEMs and treated fabrics could change from cool-tone (blue) to warm-tone (red), which significantly improved the color change range of the thermochromic material and made the color vary between different tones instead of changing in the region of similar color. The TCEMs exhibited great potentiality in the applying fields of decoration, anti-counterfeiting, architecture and intelligent textile, etc. [ABSTRACT FROM AUTHOR]