Enhancement of the energy storage and electrocaloric effect performances in 0.4 BCZT–0.6 BSTSn medium-entropy ceramic prepared by sol-gel method

Perovskite ferroelectric ceramics with large energy storage density and electrocaloric (EC) effect at a low-electric field are very attractive in modern electronic devices such as capacitors and solid refrigerators. In this work, it is demonstrated that the energy storage and EC performances of the BiFeO3 (BFO)-doped Bi[Formula: see text]Na[Formula: see text]TiO3-BaTiO3 (BNT-BT)-based ceramics near the MPB (0.89Bi[Formula: see text]Na[Formula: see text]TiO3–0.11BaTiO[Formula: see text] can be regulated by using the strain-modified calcined powders as sintering precursor. The 0.89Bi[Formula: see text]Na[Formula: see text]TiO3–0.11BaTiO3 ceramic prepared from the strain-modified calcined powder with a nanoscaled size (abbreviated as nanoceramic) simultaneously obsesses a large energy density ([Formula: see text] 0.847 J/cm[Formula: see text] and a high-energy storage efficiency ([Formula: see text] 80%) in a broad temperature range (333–453 K) at a very low-electric field ([Formula: see text] 80 kV/cm). The high-energy storage performance maybe is related to the breaking of the ferroelectric long-range order inherited from the strain-modified calcined powder with an ultra-fine size ([Formula: see text] 110 nm). Moreover, a large negative EC effect ([Formula: see text]−1.1 K) at a very low-electric field ([Formula: see text] 29.8 kV/cm) was also achieved for the ceramic prepared by using the submicro-sized calcined powder with a BFO doping amount of 6% (mole ratio). It is concluded that using strain-modified calcined powder as a sintering precursor for ceramic preparing can be used as an alternative candidate strategy to improve and optimize the energy storage and EC performances.

Flexible ferroelectric PMN–35PT thick film structures with energy storage, piezoelectric and electrocaloric performance were prepared by the room-temperature aerosol deposition method.

In this work, a systematic approach of waste (thermal/mechanical) energy harvesting and storage potential is studied in Ba0.85Zr0.15TiO3 (BZT) ceramics. The effect of stress on energy storage density (harvesting/storage) and electrocaloric performance is also studied. For this purpose, polarization–electric field hysteresis loops were recorded at various temperatures and uniaxial compressive stress. The Olsen cycle and electro-mechanical cycle are used for direct waste heat or mechanical energy to electrical energy conversion. A thermal energy-harvesting density of 42 kJ/m3 per cycle was obtained when the Olsen cycle was operated between 296–343 K and 0.25–1.5 MV/m. The electro-mechanical cycle-based energy harvesting is estimated as 78 kJ/m3 under the applied stress of 5–160 MPa and the electric field of 0.25–1.5 MV/m. The energy storage density is found as 39 kJ/m3 at zero stress field and 343 K, which increases to 53 kJ/m3 under the biased stress of 80 MPa in a wide operating temperature range of 296–328 K. It is observed that the high energy storage is a result of the reduction of the hysteresis loss. The electrocaloric temperature is found as 0.16 K and 0.18 K under the 0 and 80 MPa stress fields, respectively. Overall, the reported findings will enrich our understanding of the stress effect on BZT materials, which offers high performance for energy harvesting and storage-based applications. Moreover, this work can be also helpful in improving the energy storage density and electrocaloric effect via stress confinement.

Integrated structural and functional analysis of Ba1-xSrxTiO3-Bi0.5Na0.5TiO3 ceramics: Insights into energy storage and electrocaloric performance

Ultrahigh energy storage performances derived from the relaxation behaviors and inhibition of the grain growth in La doped Bi5Ti3FeO15 films

A binary metal phosphide (NiCoP) has been synthesized in a single-step hydrothermal method, and its energy conversion (hydrogen evolution reaction; HER) and energy storage (supercapacitor) performances have been explored. The physicochemical characterization of the NiCoP nanostructures show that they have a highly crystalline phase and are formed uniformly with a sphere-like surface morphology. In acidic electrolytic conditions, the NiCoP shows excellent HER performance, requiring only 160 and 300 mV overpotential to deliver 10 and 300 mA cm−2 current density, respectively. Interestingly, it follows the Volmer–Heyrovsky reaction pathway to execute the HER with robust durability (∼15 mV increase in overpotential even after 18 h of electrolysis). In an alkaline medium (5 M KOH), NiCoP shows specific capacitance of 960 F g−1 with higher energy density (33.3 W h kg−1) and power density (11.8 kW kg−1). Moreover, it shows better reversibility (∼97% coulombic efficiency) and long cycle life (∼95% capacitance retention after 10 000 repeated cycles). The unique surface morphology and phase purity of the binary metal phosphide avails more electroactive surface/redox centers, thereby showing better electrocatalytic as well as energy storage performances. Therefore, we presume that the NiCoP would be a suitable material for future energy conversion and storage systems.

NaNbO3-based lead-free dielectric ceramics possess significant application prospects in the field of dielectric capacitors. However, their development is hindered by low recoverable energy storage density (W rec) and energy storage efficiency (η). Herein, novel NaNbO3-based ceramics, (1-x) [0.7Na0.97Sm0.01NbO3-0.3(Sr0.7Bi0.2)(Ti0.8Zr0.2) O3]-xCaTiO3, were created by adding CaTiO3 linear dielectric, aiming to improve its energy storage performances (ESP). The phase structure, microstructure, dielectric properties, energy storage and charge-discharge performances of the ceramics were methodically analyzed. All components of the ceramics exhibit a perovskite structure consisting of two phases: antiferroelectric P-phase (AFE P) and antiferroelectric R-phase (AFE R), with the AFE R phase increasing as x rises. All ceramic surfaces exhibit clear grain morphology. The resultant ceramics have an appropriate dielectric constant and a small dielectric loss, which is beneficial for improving breakdown field strength (E b). Finally, at an E b of 470 kV/cm, 0.85[0.7Na0.97Sm0.01NbO3-0.3(Sr0.7Bi0.2)(Ti0.8Zr0.2) O3]-0.15CaTiO3 ceramic achieved optimal ESP: W rec = 3.9 J/cm3, η = 72.49%. In addition, it has remarkable stability with temperature and frequency in energy storage, and also displays an ultrafast speed in the charge-discharge process (t 0.9 = 27 ns).

A highly conducting porous architecture with plenty of stable oxygen‐containing groups is designed to endow graphene electrodes with both high rate performance and high capacitance in energy storage. By exposing the graphene oxide/Ni foam composite to an epitaxial flame of a lighter for a few seconds, the resultant reduced graphene oxide/Ni foam (RGO/Ni foam) composite shows a three‐dimensional hierarchical porous structure with plenty of stable oxygen‐containing groups, owing to the expansion and moderate reduction of graphene oxide sheets inside the Ni foam. As a supercapacitor electrode, the porous RGO/Ni foam composite exhibits an exceptional specific capacitance of 407.2 F g−1 at 500 mA g−1. An enlarged operation voltage of 1.8 V is also realized when packaging the RGO/Ni foam composite into a symmetric two‐electrode cell configuration, exhibiting high energy density and power density. As an anode electrode in a lithium‐ion battery, the first discharge/charge capacities of the RGO/Ni foam composite are 2194/1372 mA h g−1 at 100 mA g−1. This work gives great inspiration for the large‐scale production of high‐performance graphene‐based electrodes for energy storage.

Energy storage properties in SrTiO3–Bi3.25La0.75Ti3O12 thin films

A wet chemical route is reported for synthesising organic molecule stabilized lead sulfide nanoparticles. The dielectric capacitance, energy storage performances and field-driven polarization of the organic–inorganic hybrid system are investigated in the form of a device under varying temperature and frequency conditions. The structural analysis confirmed the formation of the monoclinic phase of lead sulfide within the organic network. The band structure of lead sulfide was obtained by density functional theory calculation that supported the semiconductor nature of the material with a direct band gap of 2.27 eV. The dielectric performance of the lead sulfide originated due to the dipolar and the space charge polarization. The energy storage ability of the material was investigated under DC-bias conditions, and the device exhibited the power density values 30 W/g and 340 W/g at 100 Hz and 10 kHz, respectively. The electric field-induced polarization study exhibited a fatigue-free behaviour of the device for 103 cycles with a stable dielectric strength. The study revealed that the lead sulfide-based system has potential in energy storage applications.

Polypropylene (PP)‐based dielectric film capacitors cannot meet the rapid development requirements of electromagnetic energy equipment because of their low energy storage density (Ue). The development of new dielectric materials is hampered by the trade‐off between high energy storage properties and thin film processibility for capacitors. This study proposes a strategy to improve the comprehensive energy storage properties of PP films by reconciling the trade‐offs not only between their polarity and crystallinity but also between their energy storage and processing performance. In this approach, a trifluoroethyl methacrylate (TFEMA) modified PP film is fabricated at the kilogram scale. The TFEMA units regulate PP crystallization in the α‐phase, resulting in improved mechanical, dielectric, and energy storage performance. The optimal PP‐g‐TFEMA film exhibits a remarkable breakdown strength (Eb) of 865 MV m−1 and a record Ue of 8.2 J cm−3 at over 90% discharge efficiency. The promising thin film processibility, excellent self‐healing, and long‐term reliability of PP are finely preserved in the aluminum (Al) coated PP‐g‐TFEMA film. These findings present a novel avenue to significantly increase the Ue of film capacitors for long‐term service not only in academia but also in industry.

PLZT 6/80/20 thin films prepared by the sol–gel method exhibit excellent energy storage, pyroelectric and electrocaloric performances, making them suitable for power and thermal management of chips.

ABSTRACTThis study presents an approach to enhancing dielectric properties, energy storage performance, and thermal stability of polymer composite. A dielectric composite film based on polyarylene ether nitrile (PEN) was prepared, in which SiC acted as fillers. PEI and PDA layers were co‐deposited on the surface of SiC particles to improve the dispersion of the SiC filler in the PEN resin. Benefiting from SiC's thermal stability and rigidity, the composites exhibit good thermal conductivity and low coefficient of thermal expansion. Besides, the introduction of SiC@PDA‐PEI enables the composite film to have superior electrical insulation, with a breakdown field strength of up to 195 kV/mm, 63.9% higher than that of pure PEN film. Moreover, the dielectric constant of composite films increased from 3.3 to 5.0 as the PEN/SiC@PDA‐PEI addition content increased, resulting in a significant increase in the energy storage density of the composite films. When the PEN/SiC@PDA‐PEI addition content was 2 wt%, the energy storage density of the composite film was 233% higher than pure PEN film. Therefore, this multifunctional composite film shows broad application potential in electronics, aerospace, and high‐end manufacturing fields.

To meet the increasing demands of modern power electronics for high‐temperature resistance and energy storage performance and avoid the trade‐off between high energy storage (Ue) performance and prominent processability, a strategy to modify polypropylene (PP) by introducing polar electron‐deficient 8‐hydroxyquinoline (8‐HQ) physically during melt extrusion granulation is proposed. 8‐HQ molecules are initially designed to capture charges injected under a high electric field and depress the leakage current density. Unexpectedly, they are found to reside at PP grain boundaries, promoting grain growth and thereby enhancing PP films' mechanical strength. Both effects may address the enhanced breakdown strength (Eb) up to 814 MV m−1. Besides, 8‐HQ increases the permittivity of modified PP films. Due to simultaneously enhanced Eb and dielectric constant, an impressive Ue of 9.87 J cm−3 with a discharge efficiency above 90% is obtained in the optimal sample, and an Ue of 6.96 J cm−3 at 83% efficiency is well retained up to 125 °C, far exceeding the previously reported results. This study offers a novel strategy to modify PP film physically by manipulating its crystalline behavior for high‐pulse energy storage capacitor applications.

MXenes: An exotic material for hybrid supercapacitors and rechargeable batteries