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Polymer dielectrics with excellent capacitive performance are urgently needed in advanced electrical and electronic systems. However, due to the dramatic increase in the conduction loss, the energy density and efficiency of polymers degrade severely at elevated temperatures, limiting their application in harsh environments up to 150 °C. Herein, an all-organic polyurea (PU)/polyetherimide (PEI) blend film is designed to prepare high-temperature polymer dielectric. It is found that carrier traps can be introduced by blending, and the hydrogen bond between PU and PEI increases the trap depth, leading to suppressed leakage current and enhanced breakdown strength, thus improving the energy storage performance. PU/30%PEI exhibits a high discharged energy density of ∼3.74 J/cm3 with an efficiency higher than 90% at 150 °C, which is 78% and 70% higher than pristine PU and PEI, respectively. This work provides a facile strategy to improve the energy storage performance of polymer dielectrics by introducing deep traps through blending. [ABSTRACT FROM AUTHOR]

In the pursuit of sustainable energy solutions, the development of materials with efficient hydrogen and methane storage capacities is imperative, particularly for advancing hydrogen-powered vehicles. Metal–organic frameworks (MOFs) have emerged as promising candidates to meet the stringent targets set by the Department of Energy for both hydrogen and methane storage. This study employs Grand Canonical Monte Carlo simulations to investigate the usable hydrogen and methane gravimetric and volumetric storage capacities of the recently synthesized SIGSUA. A comparative analysis encompasses the selected MOFs with similar metal compositions, those with comparable density and average pore radius, and classical benchmarks, such as IRMOF-15 and IRMOF-20, all evaluated at room temperature and moderate pressures ranging from 25 to 35 MPa. The results reveal that SIGSUA demonstrates noteworthy gravimetric and volumetric storage capacities for both hydrogen and methane, rivaling or surpassing those of the selected MOFs for analysis. These findings underscore the potential of SIGSUA in advancing clean energy storage technologies. [ABSTRACT FROM AUTHOR]

AgNbO3 (AN)-based lead-free antiferroelectric ceramics are widely studied for their use as dielectric capacitor materials. In this study, Eu3+-doped AN ceramics were prepared and the results show that Eu3+ diffused into the AN lattice. The ceramics were formed by M1 and M2 phases coexisting at room temperature, as distinct from the M1 (M: monoclinic) phase of pure AN. Electrical properties and structural characterization showed that the antiferroelectric stability of the ceramics increases with the increase in Eu3+ levels. At room temperature, Ag0.94Eu0.02NbO3 ceramic exhibited a good energy storage density of 5.3 J/cm3 and a high efficiency of 71.9%. When the temperature rises from room temperature to 140 °C, the efficiency of the sample decreases from 80.4% to 67.1% and Wr decreases from 2.1 to 2.0 J/cm3, which indicates that the sample has good temperature stability. The time constant (t0.9) of this sample was less than 60 ns and the power density (PD) was 51.3 MW/cm3, indicating excellent charge–discharge capabilities. This novel ceramic is expected to be used as a new dielectric capacitor material for pulsed power supplies. [ABSTRACT FROM AUTHOR]

The global demand for high energy density batteries, mostly for application in electric vehicles, offering increased durability, safety, and sustainability is growing rapidly. In the past, this demand has been met primarily by the development and/or improvement of new/established battery materials and technologies. The high-entropy design concept—aiming at increasing chemical complexity/occupational disorder—has recently been introduced into the field of electrochemical energy storage. Various high-entropy battery materials that are seemingly capable of outperforming low-entropy counterparts by offering desirable properties have been reported. However, future studies are required to explore if the concept is broadly applicable and can be extended to all types of battery materials, especially those that are of industrial relevance. Herein, we provide a brief overview of the existing high-entropy anodes, cathodes, and solid/liquid electrolytes for use in rechargeable Li- or Na-ion batteries and discuss potential research directions and opportunities. [ABSTRACT FROM AUTHOR]

Dielectric capacitors prepared by antiferroelectric (AFE) materials have the advantages of large power density and fast discharge ability. It has been a focus on the improvement of the recoverable energy density (Wrec) and discharge energy–density (Wdis) in the AFE ceramics. To address the above issue, optimizing the proportion of components is proposed for enhancing ceramic antiferroelectricity, ultimately improving the breakdown strength (Eb) and Wrec. In this work, an ultrahigh Wrec (14.3 J/cm3) with an excellent energy efficiency (η) of 81.1% is obtained in (Pb0.96Sr0.02La0.02)(Hf0.9Sn0.1)O3 AFE ceramic at electric field of 490 kV/cm, which is the maximum value reported in lead-based AFE ceramics fabricated by the conventional solid-state reaction method so far. The multistage phase transition induced by the electric field is observed in the polarization–electric field (P–E) hysteresis loops. Furthermore, an outstanding power density (PD) of 335 MW/cm3 and an excellent Wdis of 8.97 J/cm3 with a rapid discharge speed (102 ns) are obtained at electric field of 390 kV/cm. In addition, (Pb0.96Sr0.02La0.02)(Hf0.9Sn0.1)O3 ceramics also possess an excellent thermal and frequency stability. These exceptional properties indicate that (Pb0.98−xSrxLa0.02)(Hf0.9Sn0.1)O3 ceramics are a potential candidate for pulsed power devices and power electronic devices. [ABSTRACT FROM AUTHOR]

Increasingly, society requires high power, high energy storage devices for applications ranging from electric vehicles to buffers on the electric grid. Supercapacitors are a promising contribution to meeting these demands, though there still remain unsolved practical problems. Molecular dynamics simulations can shed light on the relevant molecular level processes in electric double layer capacitors, but these simulations are computationally very demanding. Our focus here is on the algorithmic complexity of the constant potential method (CPM), which uses dedicated electrostatics solvers to maintain a fixed potential difference between two conducting electrodes. We show how any standard electrostatics solver—capable of calculating the energies and forces on all atoms—can be used to implement CPM with a minimum of coding. As an example, we compare our generalized implementation of CPM, based on invocations of the particle–particle–particle–mesh routine of the Large-scale Atomic/Molecular Massively Parallel Simulator, with a traditional implementation based on a dedicated re-implementation of Ewald summation. Both methods yield comparable results on four test systems, with the former achieving a substantial gain in speed and improved scalability. The step from dedicated electrostatic solvers to generic routines is made possible by noting that CPM's traditional narrow Gaussian point-spread of atomic charges on the electrodes effectively endows point-like atoms with chemical hardness, i.e., an intra-atomic energy quadratic in the charge. [ABSTRACT FROM AUTHOR]

VO2 polymorphs present a unique opportunity to unravel diverse electronic properties possessed by their metastable phases. A highly reproducible, single-phase, and inexpensive synthesis method is challenging for obtaining VO2 polymorphs. Recent years have witnessed some exciting success in the growth and application of a wide range of VO2 polymorphs. This comprehensive review article delves into different polymorphs, including VO2(x) (x = A, B, M, R, C, P, and D), and investigates their distinct physical attributes. The primary focus of this article centers on providing a thorough overview of the recent progress made in stabilizing VO2(A) and VO2(B) polymorphs, emphasizing the significance of the coexistence of nanodomains at the film–substrate interface in stabilizing specific metastable phases. Additionally, the review article delves into advancements in understanding the phase transition mechanism, adjusting the order parameter in resistivity, and modifying the metal–insulator transition (MIT) temperature through doping. It also summarizes the structural, optical, electronic, and interface properties of these polymorphs and highlights their potential applications in next-generation electronic devices, particularly in the fields of sensing and energy storage. [ABSTRACT FROM AUTHOR]

The intrinsically low electrical conductivity and poor structural fragility of MnO2 have significantly hampered the zinc storage performance. In this work, Ba2+-implanted δ-MnO2 nanosheets have been hydrothermally grown on a carbon cloth (Ba–MnO2@CC) as an extremely stable and efficient cathode material of aqueous zinc-ion batteries. The three-dimensionally porous architecture composed of interwoven thin MnO2 nanosheets effectively shortens the electron/ion transport distances, enlarges the electrode/electrolyte contact area, and increases the active sites for the electrochemical reaction. Meanwhile, Ba2+ could function as an interlayer pillar to stabilize the crystal structure of MnO2. Consequently, the as-optimized Ba–MnO2@CC exhibits remarkable Zn2+ storage capabilities, such as a high capacity (305 mAh g−1 at 0.2 A g−1), prolonged lifespan (95% retention after a 200-cycling test), and superb rate capability. The binder-free cathode is also applicable for flexible energy storage devices with attractive properties. The present investigation provides important insights into designing advanced cathode materials toward wearable electronics. [ABSTRACT FROM AUTHOR]

The effects of the electrical parameters, including storage capacitance, additional inductance, charging voltage, and electrode gap, on the shock wave induced by spark discharge in gas were experimentally investigated. The results showed that the shock waves induced by spark discharge conform to the attenuation law for weak spherical shock waves outside the spark core. The shock wave amplitude is approximately proportional to the electrode gap and storage energy and decreases with increasing inductance. The effect of the charging voltage on the shock wave amplitude can be almost ignored if the storage energy is the same. The average power in the first quarter cycle of spark discharge was found to be closely related to the shock wave amplitude. An empirical equation was given between the shock wave amplitude and the average discharge power, which provides convenient access to set appropriate electrical parameters to generate shock waves of specified amplitude induced by spark discharge. [ABSTRACT FROM AUTHOR]

Aqueous Zn-ion hybrid supercapacitors (AZHSCs) combining the advantages of high‐energy batteries and high‐power supercapacitors see a bright future, but they still suffer from the poor capacity of carbonic cathodes. Herein, a functionalized porous carbon cloth (denoted as FPCC) electrode is demonstrated based on commercial carbon cloth (denoted as CC) tuning by structural and surface engineering. The constructed exfoliated porous carbon layer and the negatively charged functionalized interface not only increase the electrical double layer capacitance but also favor the chemical adsorption of Zn2+ to obtain additional pseudocapacitance. Consequently, the FPCC electrode delivers a high capacity of 0.16 mAh cm−2 at 4 mA cm−2, which is 923.8 times higher than CC, and a long cycle life (85.0% capacity retention after 30 000 cycles). More importantly, the Zn//FPCC AZHSC possesses an impressive energy density (3.3 mWh cm−3) and power density (240 mW cm−3), superior to many advanced batteries and supercapacitors. The quasi-solid-state device is also assembled as a demo. This modification strategy may provide new opportunities for high-performance AZHSCs. [ABSTRACT FROM AUTHOR]

The pursuit of advanced materials to meet the escalating demands of energy storage system has led to the emergence of vertical graphene (VG) as a highly promising candidate. With its remarkable strength, stability, and conductivity, VG has gained significant attention for its potential to revolutionize energy storage technologies. This comprehensive review delves deeply into the synthesis methods, structural modifications, and multifaceted applications of VG in the context of lithium–ion batteries, silicon-based lithium batteries, lithium–sulfur batteries, sodium–ion batteries, potassium–ion batteries, aqueous zinc batteries, and supercapacitors. The review elucidates the intricate growth process of VG and underscores the paramount importance of optimizing process parameters to tailor VG for specific applications. Subsequently, the pivotal role of VG in enhancing the performance of various energy storage and conversion systems is exhaustively discussed. Moreover, it delves into structural improvement, performance tuning, and mechanism analysis of VG composite materials in diverse energy storage systems. In summary, this review provides a comprehensive look at VG synthesis, modification, and its wide range of applications in energy storage. It emphasizes the potential of VG in addressing critical challenges and advancing sustainable, high-performance energy storage devices, providing valuable guidance for the development of future technologies. [ABSTRACT FROM AUTHOR]

Dielectric energy storage capacitors offer great potential in pulsed power devices due to the high power density and fast charging-discharging rate. Designing a host material with high field-induced polarization is of importance for developing dielectric energy storage materials via further composition modulation. In this paper, we compare the microstructure, dielectric, and ferroelectric properties as well as the energy storage performance of samples K1/2Bi1/2TiO3(KBT), 75KBT-25BiFeO3 (KBTF25), and 88KBT-12Bi0.85Nd0.15FeO3 (KBNTF12) in detail. It is found that, among three samples, sample KBNTF12 possesses the most complex local structure coexisting of a four-distortions with different polarities; meanwhile, sample KBNTF12 behaves as a strong relaxor, thus giving a high field-induced polarization. Besides, sample KBNTF12 realizes the highest electric breakdown strength Eb among three samples, which is resorted to the highest resistivity of grain boundary. Highest ΔP and Eb of sample KBNTF12 among three samples render it achieve ultrahigh stored energy density Ws of 6.94 J/cm3, high recoverable energy density Wr of 5.23 J/cm3, and high efficiency η of 75.4%. Our work suggests that 88KBT-12BNF binary composition be an optimal candidate for dielectric energy storage ceramics. [ABSTRACT FROM AUTHOR]

The transition to renewable energy sources comes along with the search for new energy storage solutions. Molecular solar thermal systems directly harvest and store solar energy in a chemical manner. By a suitable molecular design, a higher overall efficiency can be achieved. In this study, we investigate the surface chemistry of oxa-norbornadiene/quadricyclane derivatives on a Pt(111) surface. Specifically, we focus on the energy storage and release properties of molecules that are substituted with ester moieties of different sizes. For our model catalytic approach, synchrotron radiation-based x-ray photoelectron spectroscopy measurements were conducted in ultra-high vacuum (UHV) and correlated with the catalytic behavior in the liquid phase monitored by photochemical infrared reflection absorption spectroscopy. The differences in their spectral appearance enabled us to unambiguously differentiate the energy-lean and energy-rich isomers and decomposition products. Next to qualitative information on the adsorption motifs, temperature-programmed experiments allowed for the observation of thermally induced reactions and the deduction of the related reaction pathways. We analyzed the selectivity of the cycloreversion reaction from the energy-rich quadricyclane derivative to its energy-lean norbornadiene isomer and competing processes, such as desorption and decomposition. For the 2,3-bis(methylester)-substitution, the cycloreversion reaction was found to occur between 310 and 340 K, while the thermal stability limit of the compounds was determined to be 380 K. The larger 2,3-bis(benzylester) derivatives have a lower apparent adsorption energy and a decomposition onset already at 135 K. In the liquid phase (in acetonitrile), we determined the rate constants for the cycloreversion reaction on Pt(111) to k = 5.3 × 10−4 s−1 for the 2,3-bis(methylester)-substitution and k = 6.3 × 10−4 s−1 for the 2,3-bis(benzylester) derivative. The selectivities were of >99% and 98% for the two molecules, respectively. The difference in the catalytic behavior of Pt(111) for both derivatives is less pronounced in the liquid phase than in UHV, which we attribute to the passivation of the Pt(111) surface by carbonaceous species under ambient conditions. [ABSTRACT FROM AUTHOR]

Electric field distortion caused by space charge accumulation is one of the challenges in the development of insulating liquid immersed converter transformers and battery energy storage. This paper studies the impact of temperature and moisture content on field distortion in synthetic ester through an improved computational model incorporating the time-development permittivity of insulating liquid, and the test results indicated highly accurate simulation results of electric field distribution can be produced compared with the previous model. Charge mobility and charge density in synthetic ester were extracted from frequency dielectric spectroscopy test results, which were then used to calculate field distortion by the developed computational model. Simulation results indicated that the field distortion in synthetic ester decreases with temperature due to the enhanced permittivity caused by space charge accumulation, while it increases with moisture content due to the increased charge density from the dissociation of water. [ABSTRACT FROM AUTHOR]

Probing the chemistry and materials science of electrochemical energy materials is a central topic in both chemical physics and energy chemistry due to the increasingly important role of energy devices in the current and future energy system and industry. Especially, understanding the chemical physics of electrochemical energy materials is the key to enhance the performance of energy storage and conversion devices such as batteries, fuel cells, electrolyzers, and supercapacitors. This special topic focuses on the fundamental understanding of electrochemical energy applications, including electrochemistry fundamentals, structural dynamics and degradation mechanism of materials, optimization strategies for improving electrochemical performance of energy devices, and emerging simulation and characterization methods applied to advanced energy materials. [ABSTRACT FROM AUTHOR]

In modern electronics and power systems, good-performance dielectric capacitors have an essential function. Polymer-based dielectrics are widely used in the field of dielectric capacitors because of their large dielectric constant, flexibility, low density, and ease of processing. At present, ferroelectric polymers suffer from low breakdown field strength and high dielectric losses. How to improve the performance of dielectric materials in capacitors is still a promising research. This paper chooses the ferroelectric polymer poly(vinylidene fluoride) (PVDF) that worked as the matrix, and the linear polymers polyimide, cyanoethyl pullulan (CR-S), polyethersulfone, and cyanoethylated cellulose served as fillers. This all-organic dielectric composite produced as films working in electrostatic energy storage devices is prepared by using a casting method. Analyzing the test results, the composite film exhibited excellent electrical properties when the CR-S doping content was 5 wt. %. The organic composite dielectric based on CR-S/PVDF has a breakdown field strength of 450 MV/m, a discharge energy storage density (Ue) of 10.3 J/cm3, a high dielectric constant of 10.9, and a low dielectric loss of 0.004 at 1 kHz, which is a significant improvement compared with other dielectric composites. This all-organic dielectric composite strategy offers a new approach to achieve better-performance dielectric energy storage materials. [ABSTRACT FROM AUTHOR]

The growing demand for improved electrochemical performance in energy storage systems has stimulated research into advanced two-dimensional (2D) materials for electrodes. In this work, we obtain a layered MXene compound by exfoliating a titanium aluminum carbide precursor using tetramethylammonium hydroxide (TMAOH) ions in a full room temperature process followed by manual shaking. The hexagonal crystal structure and composition of the layered materials are characterized using different techniques. X-Ray diffraction shows the formation of 2D nano-sheets before and after the TMAOH treatment via its characteristic (002) diffraction peak, bringing to light an increase in the interlayer spacing after treatment. Scanning electron microscopy images confirm the layered morphology, whose composition is determined by energy dispersive x-ray analysis for the bulk material and by x-ray photoelectron spectroscopy for the surface of the obtained compounds. This study demonstrates a promising route to enhance delamination of this MXene 2D material in a low-cost room-temperature approach. [ABSTRACT FROM AUTHOR]

Transference number is a key design parameter for electrolyte materials used in electrochemical energy storage systems. However, the determination of the true transference number from experiments is rather demanding. On the other hand, the Bruce–Vincent method is widely used in the lab to approximately measure transference numbers of polymer electrolytes, which becomes exact in the limit of infinite dilution. Therefore, theoretical formulations to treat the Bruce–Vincent transference number and the true transference number on an equal footing are clearly needed. Here, we show how the Bruce–Vincent transference number for concentrated electrolyte solutions can be derived in terms of the Onsager coefficients, without involving any extrathermodynamic assumptions. By demonstrating it for the case of poly(ethylene oxide)–lithium bis(trifluoromethane)sulfonimide system, this work opens the door to calibrating molecular dynamics (MD) simulations via reproducing the Bruce–Vincent transference number and using MD simulations as a predictive tool for determining the true transference number. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (AZIBs) have emerged as competitive alternatives for energy storage systems. By comparison with traditional cathode materials, the unique combination advantages of improved specific capacity, high electrical conductivity and tunable structures exhibited by chalcogenides contribute to receiving increasing attention. However, it should be noted that chalcogenides still show unsatisfactory electrochemical performance in aqueous batteries, because of their inferior chemical stability and sensitivity to pH value in aqueous media. Consequently, the application of chalcogenides in AZIBs still requires further investigation and optimization. This review offers a systematic summary of recent advancements in the rational design strategies employed to develop advanced cathode materials derived from chalcogenides. Furthermore, the review comprehensively presents the applications of various transition metal dichalcogenides, as well as sulfur (S), selenium (Se), tellurium (Te), and their corresponding solid solutions, in AZIBs. Lastly, the challenges currently confronting chalcogenides research are deliberated upon, followed by a perspective outlining future directions for practical applications of AZIBs. [ABSTRACT FROM AUTHOR]

The impact of the sintering temperature on the phase composition and electrical properties of 5% SrTiO 3 –95%BaZr 0.15 Ti 0.85 O 3 (ST-BZT) ceramics fabricated by solid-state method and consolidated by two-step sintering is presented. A systematic analysis of the phase composition, microstructures, dielectric, ferroelectric, and energy storage characteristics. A di-phase SrTiO 3 –BaZrTiO 3 composite is obtained at low sintering temperatures below 1400 °C. Increasing the sintering temperature causes a shift of the Curie temperature from 62 °C to 55 °C together with changes of permittivity values and of the ferroelectric loops, thus indicating a progressive interdiffusion process at the interfaces, together with a better densification. Remarkably, the ST-BZT composition sintered at 1500 °C exhibits characteristics of a single phase (Ba,Sr) (Zr,Ti)O 3 solid solution, with high room temperature permittivity around 2950 and good ferroelectric response (saturation polarization P max = 12.6 μC/cm2 and remnant polarization P r = 2.16 μC/cm2). Consequently, this composition displays a much greater recoverable energy density (W rec = 54.5 mJ/cm3) in comparison to the ones of the di-phase ST-BZT composites and the parent phases. However, the (Sr 0.05 Ba 0.95) (Zr 0.14 Ti 0.86)O 3 solid solution, demonstrates a lower energy efficiency (72%) in comparison to the ST-BZT di-phase composites sintered at lower temperatures, which exhibit higher energy efficiency values around 86%. In addition, the charge-discharge experiments were performed under different electric fields to disclose the difference in energy storage properties in 5% SrTiO 3 –95%BaZr 0.15 Ti 0.85 O 3 ceramics. This suggests that the sintering strategy plays a crucial role in determining the energy efficiency of the obtained ceramics. Additionally, all the investigated ST-BZT ceramics present high energy efficiency at low-applied electric fields, suggesting their potential as candidates for energy storage capacitors operating at moderate fields. [ABSTRACT FROM AUTHOR]

High-entropy perovskite oxides (HEPOs) have attracted considerable attention as dielectric ceramics. However, the energy-storage performance of these HEPOs still requires improvement. In this study, a series of (1- x)(Bi 0. 4 Ba 0. 2 K 0. 2 Na 0.2)TiO 3 - x NaNbO 3 high-entropy ceramics were designed and prepared using a high-entropy strategy. The introduction of antiferroelectric NaNbO 3 into the (Bi 0. 4 Ba 0. 2 K 0. 2 Na 0.2)TiO 3 medium-entropy matrix increased the configurational entropy and cationic disorder, resulting in improved energy storage performance. The ceramic with an optimal composition of 0.775(Bi 0. 4 Ba 0. 2 K 0. 2 Na 0.2)TiO 3 -0.225NaNbO 3 achieved a high recoverable energy density (W rec) of 2.523 J/cm3 and a high efficiency (η) of 83.7% at an electric field of 220 kV/cm. Furthermore, the material demonstrated good temperature and frequency stability, as well as good anti-fatigue properties. This paper presents a dielectric ceramic suitable for energy storage under low to moderate electric fields. [ABSTRACT FROM AUTHOR]

The energy storage properties of pure PLZST-based antiferroelectric ceramics are excellent; however, the high sintering temperature renders them unsuitable for co-firing with copper inner electrodes as MLCC dielectric materials. The proven BASK glass additive was employed in this study to lower the sintering temperature of PLSZT ceramics, while simultaneously doping Sm3+ ions to enhance their sintering performance under reducing atmospheres. The precise evaluation process confirmed that the addition of glass effectively reduced the sintering temperature to 1040 °C. Furthermore, the defect association of Sm3+ doping hindered the formation of oxygen vacancies, facilitated ceramic grain growth, and significantly enhanced insulation resistivity. Consequently, an ultrahigh recoverable energy density (W rec) of 5.19 J/cm3 with a high energy storage efficiency (η) of 94.5% are achieved at an electric field of 430 kV/cm. Moreover, the AFE ceramics possess excellent discharge energy storage properties with a high discharge energy density (W d) of 4.26 J/cm3 and a large power density (P d) of 139 MW/cm3. [ABSTRACT FROM AUTHOR]

Novel materials with highly synchronized electrochromic (EC) and energy storage properties are needed to simultaneously visualize and quantify the real-time charge state of energy storage devices. Herein, a film was prepared by the Layer-by-Layer assembly of W 18 O 49 nanowires and a Preyssler-type polyoxometalate (POM) [P 5 W 30 O 110 ]15− (P 5 W 30). The introduction of amorphous POM decreased the band gap to 2.54 eV, which greatly facilitated the synergy between the EC and charge storage properties. Driven under a low voltage of −0.6 V, this W 18 O 49 /P 5 W 30 composite film displayed strong and reversible changes in its optical absorbance in both the visible and near-infrared regions, and it also showed the typical pseudocapacitance behavior with an area capacitance of 34.71 mF cm−2. Moreover, this film was able to simultaneously quantify and visualize its own energy storage state and photothermal conversion in real time by significant color changes (maximum chromaticity difference: 72.44) and high absorbance changes (1.11 at 650 nm and 1.11 at 1200 nm). In addition, a gel EC supercapacitor based on the W 18 O 49 /P 5 W 30 film as cathode and NiO film as anode exhibited an absorbance variation up to 0.75 and an area capacitance as high as 4.42 mF cm−2, and it successfully powered a light emitting diode using the stored electrical energy. This work not only broadens the application scope of POM-based EC materials but also provides a feasible design strategy for next-generation smart energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

In research out of the sustainable electrochemical energy storage material, NiCo-LDH/MnO 2 composite has been prepared via simple hydrothermal method. The experimental characterizations of XRD, SEM/TEM and XPS have been utilized to explore the structure and morphology of prepared composite. The needle-like MnO 2 was found adhered to NiCo-LDH sheet. The composite's electrochemical properties were evaluated through cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. It has been realized that the MnO 2 dosage not only changes the composite's microstructure but also affects its electrochemical properties. The best specific capacitance (2602 F g−1 at a current density of 1 A g−1) was achieved for the composite sample with 38% MnO 2 (mass), which is almost two times high from the same composite in previous reports. With the sample, the assembled asymmetric supercapacitor exhibits a remarkable energy density of 19.56 Wh.Kg−1 at 800.29 W Kg−1. It could be attributed to the synergetic effects of two components as well as their good interfacial coupling. The good electrochemical activity makes our synthesized composite feasible to be applied as electrode material and provides valuable insights for the development of smart capacitors utilizing NiCo-LDH. [ABSTRACT FROM AUTHOR]

Glass ceramic dielectric materials with high power density and high energy density have important application value in the miniaturization and integration of lightweight pulse power devices. In this work, SrO 2 –BaO 2 –Nb 2 O 5 –SiO 2 –Al 2 O 3 –B 2 O 3 glass ceramics doped with various contents of CeO 2 were prepared via high-temperature melting combined with temperature-controlled crystallization process. Results showed that CeO 2 doping increased the content of Ba 0.27 Sr 0.75 Nb 2 O 5.78 tungsten bronze phase precipitate from the glass matrix in glass ceramics (from 55.7% to 82.2%), thereby increasing dielectric constant of SrO 2 –BaO 2 –Nb 2 O 5 –SiO 2 –Al 2 O 3 –B 2 O 3 glass ceramics (from 66.5 to 101.9). Besides that, CeO 2 -doped ceramics exhibited excellent temperature stability and low loss (below 0.015). The highest breakdown strength (1590 kV/cm) and energy density (12.88 J/cm3) were achieved in the ceramic with a CeO 2 doping concentration of 3.0 mol.%, being 3.03 times higher than those in undoped glass ceramic. The increase in energy density of the ceramics was attributed to moderate CeO 2 doping concentration that improved the crystallinity (from 83.8% to 89.8%) and reduced the interfacial activation energy of the glass ceramics. [ABSTRACT FROM AUTHOR]

Bi-functional materials provide an opportunity for the development of high-performance devices. Up till now, bi-functional performance of NiCo2O4@SnS2 nanosheets is rarely investigated. In this work, NiCo2O4@SnS2 nanosheets were synthesized on carbon cloth by utilizing a simple hydrothermal technique. The developed electrode (NiCo2O4@SnS2/CC) was investigated for the detection of L-Cysteine and supercapacitors applications. As a non-enzymatic sensor, the electrode proved to be highly sensitive for the detection of L-cysteine. The electrode exhibits a reproducible sensitivity of 4645.82 μ A mM−1 cm−2 in a wide linear range from 0.5 to 5 mM with a low limit of detection (0.005 μ M). Moreover, the electrode shows an excellent selectivity and long-time stability. The high specific surface area, enhanced kinetics, good synergy and distinct architecture of NiCo2O4@SnS2 nanosheets produce a large number of active sites with substantial energy storage potential. As a supercapacitor, the electrode exhibits improve capacitance of 655.7 F g−1 at a current density of 2 A g−1 as compare to NiCo2O4/CC (560 F g−1). Moreover, the electrode achieves 95.3% of its preliminary capacitance after 10 000 cycles at 2 A g−1. Our results show that NiCo2O4@SnS2/CC nanosheets possess binary features could be attractive electrode material for the development of non-enzymatic biosensors as well as supercapacitors. [ABSTRACT FROM AUTHOR]

Composite of CoS 1.97 nanoparticles decorated CuS hollow cubes and reduced graphene oxide (rGO) (CCSrGO) thin film flexible positive electrode is fabricated as the anode material of supercapacitor with broad application prospects in electrochemical energy storage. [Display omitted] Stretchable flexible thin-film electrodes are extensively explored for developing new wearable energy storage devices. However, traditional carbon-based materials used in such independent electrodes have limited practical applications owing to their low energy storage capacity and energy density. To address this, a unique structure and remarkable mechanical stability thin-film flexible positive electrode comprising CoS 1.97 nanoparticles decorated hollow CuS cubes and reduced graphene oxide (rGO), hereinafter referred to as CCSrGO, is prepared. Transition metal sulfide CoS 1.97 and CuS shows high energy density owing to the synergistic effects of its active components. The electrode can simultaneously meet the high-energy density and safety requirements of new wearable energy storage devices. The electrode has excellent electrochemical performance (1380 F/g at 1 A/g) and ideal capacitance retention (93.8 % after 10,000 cycles) owing to its unique three-dimensional hollow structure and polymetallic synergies between copper and cobalt elements, which are attributed to their different energy storage mechanisms. Furthermore, a flexible asymmetric supercapacitor (FASC) was constructed using CCSrGO as the positive electrode and rGO as the negative electrode (CCSrGO//rGO), which delivers an energy density of 100 Wh kg−1 and a corresponding power density of 2663 W kg−1 within a voltage window of 0–1.5 V. The resulting FASC can power a light-emitting diode (LED) at different bending and twisting angles, exerting little effect on the capacitance. Therefore, the prepared CCSrGO//rGO FASC devices show great application prospects in energy storage. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developing surface structuring of Al current collectors for battery application. • Developing crack formation on the electrodes to enhance electrolyte diffusion. • Improving electrode adhesion using structured Al current collectors. • Crack formation enabling fast charging-rates and battery cycle life. Today's society and economy demand high-performance energy storage systems with large battery capacities and super-fast charging. However, a common problematic consequence is the delamination of the mass loading (including, active materials, binder and conductive carbon) from the current collector at high C-rates and also after certain cycle tests. In this work, surface structuring of aluminum (Al) foils (as a current collector) is developed to overcome the aforementioned delamination process for sulfur (S)/carbon composite cathodes of Li-S batteries (LSBs). The structuring process allows a mechanical interlocking of the loaded mass with the structured current collector, thus increasing its electrode adhesion and its general stability. Through directed crack formation within the mass loading, this also allows an enhanced electrolyte wetting in deeper layers, which in turn improves ion transport at increased areal loadings. Moreover, the interfacial resistance of this composite is reduced leading to an improved battery performance. In addition, surface structuring improves the wettability of water-based pastes, eliminating the need for additional primer coatings and simplifying the electrode fabrication process. Compared to the cells made with untreated current collectors, the cells made with structured current collectors significantly improved rate capability and cycling stability with a capacity of over 1000 mAh g−1. At the same time, the concept of mechanical interlocking offers the potential of transfer to other battery and supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

The trivalent Gd3+ ions are introduced as electrolyte additives to form an electrostatic shielding layer on the surface of the zinc anode, resulting in a highly stable and reversible zinc metal anode. [Display omitted] • The Gd3+ ions can form an electrostatic shielding layer on the zinc anode to promote the uniform deposition of Zn2+ ions. • The adsorbed Gd3+ ions acted as a buffer interface, reducing the direct contact between the zinc anode and H 2 O and thus inhibiting the interfacial parasitic reaction. • The Zn//Zn and Zn//MnO 2 cells exhibit extended cycle life and enhanced rate capability. Aqueous zinc-ion batteries (AZIBs) have become an ideal candidate for large-scale energy storage systems owing to their inherent safety and highly competitive capacity. However, severe dendrite growth and side reactions on the surface of zinc metal anodes lead to quick performance deterioration, seriously impeding the commercialization of AZIBs. In this work, a self-regulated zinc metal/electrolyte interface is constructed to solve these problems by incorporating the trivalent Gd3+ additive with a lower effective reduction potential into the aqueous ZnSO 4 electrolyte. It is revealed that the inert Gd3+ ions preferentially adsorb on the active sites of the zinc anode, and the induced electrostatic shielding layer is beneficial to uniform Zn deposition. Meanwhile, the adsorbed Gd3+ ions act as a buffer interface to lower the direct contact of the zinc anode with water molecules, thereby suppressing the interfacial parasitic reaction. These features endow the Zn//Zn battery using 0.2 M Gd3+ ions with 2940 h of cycling life at 5 mA cm−2 and a cumulative plating capacity (CPC) of 6.2 Ah cm−2 at 40 mA cm−2. When assembling with a MnO 2 cathode, the full cell using the modified electrolyte exhibits a high capacity of 268.9 mAh/g at 0.2 A/g, as well as improved rate capability and cycle stability. The results suggest the great potential of a rare earth ion additive in reinforcing Zn metal anodes for developing practical AZIBs. [ABSTRACT FROM AUTHOR]

Benefitting from the synergetic effects of heterostructured sulfide as the charge transfer accelerator and N -doped carbon matrix as an armor, the bimetallic FeS 2 /MoS 2 heterostructure confined in nitrogen-doped carbon (FMS@NC) delivers a comprehensive K-ions storage ability. Moreover, the as-built K-ion capacitor based on FMS@NC anode and activated carbon cathode achieves a high energy/power density as well as ultra-long cycling stability. [Display omitted] The means of structural hybridization such as heterojunction construction and carbon-coating engineering for facilitating charge transfer and electron transport are considered viable strategies to address the challenges associated with the low rate capability and poor cycling stability of sulfide-based anodes in potassium-ion batteries (PIBs). Motivated by these concepts, we have successfully prepared a hydrangea-like bimetallic sulfide heterostructure encapsulated in nitrogen-doped carbon (FMS@NC) using a simple solvothermal method, followed by poly-dopamine wrapping and a one-step sulfidation/carbonization process. When served as an anode for PIBs, this FMS@NC demonstrates a high specific capacity (585 mAh g−1 at 0.05 A/g) and long cycling stability. Synergetic effects of mitigated volume expansions and enhanced conductivity that are responsbile for such high performance have been verified to originate from the heterostructured sulfides and the N -doped carbon matrix. Meanwhile, comprehensive characterization reveals existence of an intercalation-conversion hybrid K-ion storage mechanism in this material. Impressively, a K-ion capacitor with the FMS@NC anode and a commercial activated carbon cathode exhibits a superior energy density of up to 192 Wh kg−1, a high power density, and outstanding cycling stability. This study provides constructive guidance for designing high-performance and durable potassium-ion storage anodes for next-generation energy storage devices. [ABSTRACT FROM AUTHOR]

Using ZIF-67 as precursor, a bimetallic oxide heterostructure of CoO/MoO 3 @NC was synthesized, and the potential of its application as a modified separator material for lithium-sulfur batteries was explored. Furthermore, the CoO/MoO 3 @NC heterostructure exhibits advanced performance in lithium-sulfur batteries, thus paving the way for the design of novel lithium-sulfur battery separator materials. [Display omitted] • Hollow bimetallic oxide heterostructures CoO/MoO 3 @NC obtained by simple hydrothermal synthesis and calcination. • CoO/MoO 3 @NC consists of a bimetallic oxide heterostructure with an outer layer of capped carbon. The bimetallic oxide heterostructure provides more active sites for adsorption of polysulfides and the carbon coating significantly improves the electrical conductivity of the bimetallic oxide heterostructure. • The Li-S battery equipped with a CoO/MoO 3 @NC modified separator exhibits a high discharge capacity of 613 mAh g−1 at 1C and a capacity decay rate of 0.092% after 500 cycles at 0.5C. • The in-situ impedance test also reveals the remarkable role of CoO/MoO 3 @NC in adsorbing polysulfides and facilitating ion transport. Lithium-sulfur batteries (LSBs) have emerged as a promising energy storage system, but their practical application is hindered by the polysulfide shuttle effect and sluggish redox kinetics. To address these challenges, we have developed CoO/MoO 3 @nitrogen-doped carbon (CoO/MoO 3 @NC) hollow heterostructures based on porous ZIF-67 as separators in LSBs. CoO has a strong anchoring effect on polysulfides. The heterostructure formed after the introduction of MoO 3 increases the adsorption of polysulfides. The carbon coating outside the heterostructure improves the ion transmission efficiency of the battery, leading to enhanced electrochemical performance. The modified LSB demonstrates a low-capacity decay rate of 0.092% over 500 cycles at 0.5C, with a high discharge capacity of 613 mAh g−1 at 1C. This work presents a novel approach for the preparation of hollow heterostructure materials, aiming for high-performance LSBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Use of a university two-step strategy to construct 3D VO 2 /CNT@PANI with core–shell architecture. • Taking full advantage of the synergistic effect, the optimal VO 2 /CNT@PANI exhibits superior electrochemical performances. • Fabrication of a full-printable in-planar symmetric supercapacitor with a remarkable areal energy density and cycling life. • Great potential application prospects in the field of portable/wearable electronics. As a progressive electronic energy storage device, the flexible supercapacitor holds tremendous promise for powering wearable/portable electronic products. Of various pseudocapacitor materials, vanadium dioxide (VO 2) has garnered extensive attention due to its impressive theoretical capacitance. However, the challenges of inferior cycling life and lower energy density to be addressed. Herein, we prepare VO 2 nanorods with winding carbon nanotubes (CNT) via a facile solvothermal route, followed by in situ polymerization of polyaniline (PANI) shell. Taking full advantage of the synergistic effect, the VO 2 /CNT@PANI composite delivers a high specific capacitance of 354.2F/g at 0.5 A/g and a long cycling life of ∼ 88.2 % over 5000 cycles resulting from the enhanced conductivity of CNT and stabilization of PANI shell. By screen printing the formulated inks with outstanding rheological behaviours, we manufacture an in-planar VO 2 /CNT@PANI symmetric supercapacitor (VO 2 /CNT@PANI SSC) device featuring an orderly arrangement structure. This device yields a remarkable areal energy density of 99.57 μWh/cm2 at a power density of 387.5 μW/cm2 while retaining approximately ∼ 87.6 % of its initial capacitance after prolonged use. Furthermore, we successfully powered a portable game machine for more than 2 min using two SSCs connected in series with ease. Therefore, this work presents a universal strategy that utilises combination and coating to boost electrochemical performance for flexible high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

CoNi LDH nanostructures with large specific surface areas were prepared through a facile sonochemical approach in the solutions with different pH values. The CoNi LDH exhibited battery-type electrochemical response with the highest capacity of 740.8C/g at 1 A/g in 2 M of KOH electrolyte. The assembled CoNi LDH//AC hybrid supercapacitor delivered the highest energy density of 35.6 W h kg−1 at the power density of 781.1 W kg−1. [Display omitted] • CoNi LDH nanostructures with large surface area were sonochemically prepared. • A high specific capacity of 740.8C/g at 1 A/g was delivered. • Just a little capacity decay over 5000 cycles at a high current density of 8 A/g. • The HSC device delivered an energy density of 35.6 W h kg−1 at 781.1 W kg−1. Fabricating battery-type electrode materials with large specific surface area and mesopores is an efficient method for enhancing the electrochemical performance of supercapacitors. This method may provide more active sites for Faradic reactions and shorten the ion-diffusion paths. In this study, the CoNi layered double hydroxides (LDHs) with the morphology of nanoflowers and nanoflakes were prepared in solutions with pH values of 7.5 (CoNi LDH-7.5) and 8.5 (CoNi LDH-8.5) via a simple sonochemical approach. These CoNi LDHs possessed large specific surface areas and favourable electrochemical properties. The CoNi LDH-7.5 delivered a specific capacity of 740.8C/g at a current density of 1 A/g, surpassing CoNi LDH-8.5 with 668.1C/g. The hybrid supercapacitor (HSC) was assembled with activated carbon as the anode and CoNi LDH as the cathode to assess its practical application potential in the field of electrochemical energy storage. The CoNi LDH-7.5//AC HSC achieved the highest energy density of 35.6 W h kg−1 at a power density of 781.1 W kg−1. In addition, both HSCs exhibited little capacity decay over 5,000 cycles at a high current load of 8 A/g. These electrochemical properties of CoNi LDHs make them promising candidates for battery-type electrode materials. The current sonochemical method is simple and can be applied to the preparation of other LDHs-based electrode materials with favourable electrochemical performance. [ABSTRACT FROM AUTHOR]

NiS/Ni@HCNF electrode enable the cell with excellent storage capacity and superior thermal safety performance. [Display omitted] • Catalytic chemistry inspired hollow carbon nanofibers loaded with NiS/Ni is designed. • Such delicate structure shows superior cycling and rate property than many TMSs. • The favorable Li+ storage actions and related reaction kinetics are discovered. • Using the designed structure markedly promotes the thermal safety of LIBs. Transition metal sulfides (TMSs) based anodes hold a very broad application prospect in lithium ion batteries (LIBs). In this work, the catalytic effect of metallic nickel at high temperature was used to generate hollow carbon nanofibers loaded with NiS and Ni (denoted as NiS/Ni@HCNF). The heteroatoms doped carbon fibers buffer the huge volumetric change of NiS during the discharge/charge process, and enhance the ion transport efficiency and electrical conductivity. In addition, the high specific surface area brought by the hollow carbon nanofibers can accelerate the electrolyte penetration and speed up the transport of ions as well as electrons. When used as anode of half cell, this electrode gives 958.5 and 612.9 mAh/g after running 1000 cycles under 1 and 2 A/g, showing the extremely-low attenuation rates of 0.0483 % per cycle and 0.0643 % per cycle, respectively. Impressively, NCM//NiS/Ni@HCNF battery shows the discharge capacity of 187.6 mAh/g at 1st cycle. Regarding the next 100 cycles, the relatively-high discharge capacities (>110 mAh/g) and coulombic efficiency (CE) values (>96 %) are discerned. It is noted that the usage of NiS/Ni@HCNF electrode improves the activation energy for thermal runaway, corroborating the elevated thermal safety of battery. [ABSTRACT FROM AUTHOR]

The generation of energy using fossil fuels is not environmentally friendly and therefore causes climate change issues. Hence, exploration of avenues for the production of clean and efficient energy is on the rise. A nonmetal-based semiconductor material called graphitic carbon nitride (g-C 3 N 4 or g-CN) is currently gaining tractions because of exceptional and interesting characteristics such as increased stability (chemical and thermal), unique bandgap energy and valence band, effective conductivity, and cost-effectiveness. This review work has thrown more light on graphitic carbon nitride in relation to hydrogen energy production and storage while taking into consideration the background, synthetic routes and optimisation of this non-metallic semiconductor. Furthermore, the work explored a number of studies on applications, hydrogen energy storage mechanisms, modelling, drawbacks and objective perspectives as it relates to efficient hydrogen energy production and storage. The efficiency, sustainability and commercialization become the driving force for future improvement in this technology. [ABSTRACT FROM AUTHOR]

Difunctional devices have great potential in the application of many areas, they can perform two functions simultaneously, and structural difunctional supercapacitor is one of them. The difunctional supercapacitor can carry out bearing capacity and storge electric energy, but it's difficult to keep the balance between bearing capacity and energy storage capacity. In this work, the montmorillonite based geopolymer has a compressive strength of 31.6 MPa after curing for 28 days, and a compressive strength of 30.5 MPa after repolymerization. We use the geopolymer as the framework, and inject 0.5 M Na 2 SO 4 into the geopolymer to prepared a structural electrolyte. Then, the structural electrolyte membrane, electrodeposited MnO 2 , and an activated carbon are assembled into a difunctional supercapacitor. The maximum specific capacity reaches 2216.7 mF cm−2 at 1 mA cm−2 under 15 MPa, achieving a good balance between compressive strength and energy storage capacity. [ABSTRACT FROM AUTHOR]

Owing to the variation of the characteristics due to the cationic substitution of diverse elements at both A and B sites, the new polycrystalline double perovskite BaBiFeMnO 6 , synthesized via a cost-efficient solid-state reaction route. Initial structural refinement by Rietveld analysis reveals material crystallised in dual phases i.e. monoclinic and orthorhombic. The respective cell parameters for monoclinic as well as orthorhombic phases are a = 5.5881 Å, b = 5.6541 Å, c = 7.9186 Å with cell angles α = γ = 900 and β = 89.90810 and a = 5.4807Å, b = 5.3583Å, c = 7.4045Å and refined angles are α = β = γ = 900 respectively. The microstructural interpretation of the present sample reflects a non-uniform distribution of the grains with an average grain size of 2.97 μm with a mean crystalline size of 342.65 nm. The Fourier-Transform Infrared Spectroscopy (FTIR) graph indicated that the sample belongs to the perovskite family. The impedance measurement was carried out in a selected frequency and an assigned temperature range to investigate the electrical features of the material which suggested the non-Debye type relaxation and negative temperature coefficient of resistance (NTCR). Furthermore, the thermistor constant (β) and temperature coefficient of resistance (TCR) contributed to investigating the NTCR characteristic of the sample under NTC-type thermistor applications. The room temperature dielectric constant is 1707.67 with a minimal tangent loss of 0.7069 at 100Hz frequency has been estimated by fitting the dielectric data by utilizing the Havrilliak-Negami function. The polarization (P) induced due to the maximum applied electric field of 1.287 kV is studied from the hysteresis loop plotted between them. The hysteresis loop indicates the ferroelectric property of the material with a lossy nature. The room temperature remnant magnetization (2M r) of 0.4424 emu/g and coercivity (2H c) of 6.2 kOe have been estimated from the M ∼ H loop. The potentiality of the material to be used as a viable candidate in various energy storage devices and supercapacitors is suggested by all of the characterisations in conjunction with the high value of ε r i.e. ∼80000 at 300 °C for the lower frequency. [ABSTRACT FROM AUTHOR]

Ceramic-based dielectric capacitors are showing great potential in advanced high-power applications. However, simultaneous achievement of high energy density (W rec) and temperature stability is still a main bottleneck. Herein, an extraordinary nanoscale structural heterogeneity is developed to promote temperature-stable energy storage in Er/Mn co-doped Bi 0.5 Na 0.5 TiO 3 based ceramics via domain and defect dipoles engineering. The composition-driven domain reconstruction by Er/Mn co-doping can induce internal random fields with rapid response to the electric field, and thus enhance ΔP and η. Meanwhile, the donor-accpetor Er/Mn doping could manipulate defect dipoles coupling to resist the applied field evolution to elevate BDS and η. Besides, the improved relaxor feature and core-shell structure give rise to the enhanced temperature stability. Ceramics with 2 mol % Er 2 O 3 demonstrate high W rec ∼2.79 J/cm3, large efficiency ∼89.4% and outstanding dielectric stability within 70–500 °C. The proposed nanostructural heterogeneity was verified as a promising pathway to manufact temperature-stable energy storage ceramics. The nanoscale structural heterogeneity via domain and defect dipoles strategies is developed to promote temperature-stable energy storage in NBT-based ceramics. [Display omitted] [ABSTRACT FROM AUTHOR]

Phase change material (PCM) is an ideal heat storage material with huge latent heat and nearly constant phase change temperature, but there are serious problems in application such as leakage and low thermal conductivity. Porous ceramic is widely used in PCM packaging because of its advantages of controllable porosity and high thermal conductivity. Porous Al 2 O 3 ceramics were prepared by foaming injection coagulation method. In order to improve the thermal conductivity of porous ceramic matrix, Porous Al 2 O 3 @Graphite Ceramics (PAGC) were prepared by sucrose decomposition. Form-Stable Phase Change Materials (FSPCMs) were prepared by adsorption of Lauric Acid/Myristic Acid (LA/MA) in PAGC by vacuum impregnation method. SEM showed that the prepared PAGC had a three-dimensional interpenetrating structure and high porosity. TEM and XPS showed that alumina skeleton were uniformly coated with graphite. After PAGC impregnated by LA/MA, the maximum PCM storage reached 62.11 wt %. The maximum latent heat of FSPCMs reaches 83.33 J/g. Thermogravimetric analysis, thermal cycling test and Fourier transform infrared spectroscopy show that the prepared FSPCMs has good thermal stability, thermal reliability, chemical stability and compressive strength. More importantly, the thermal conductivity of the prepared FSPCMs is greatly improved, reaching up to 3.73 W/mK. It is 20.72 times the original PCM, mainly due to the synergistic effect of the Al 2 O 3 skeleton and the graphite coating to build a continuous highway for heat transfer. This study provides a practical means to greatly improve the thermal conductivity of FSPCMs, which will promote the practical application of FSPCMs. [ABSTRACT FROM AUTHOR]

Dielectric (Ba 0.4 Sr 0.6)TiO 3 (BST) ceramics are promising dielectric energy storage materials due to their moderate dielectric constant, low dielectric loss, and slight nonlinearity. However, their energy density is limited by their low breakdown strength (BDS). In this study, we aimed to address this limitation by incorporating various amounts of Bi 0.2 Sr 0.7 (Mg 1/3 Nb 2/3)O 3 (SBMN) into the BST matrix. The (1– x)BST x SBMN ceramics were prepared by conventional solid-state sintering, resulting in single-phase solid solutions. Compared to pure BST ceramics, the (1– x)BST– x SBMN ceramics exhibited lower remnant polarization and significantly enhanced BDS. Furthermore, the relaxation of the ceramics enhanced with increasing doping concentration, with an efficiency of η = 94.0% achieved at x = 0.20. Among them, the breakdown field strength of 0.85BST–0.15SBMN ceramics was 597 kV cm−1, achieving a recoverable energy storage density of W rec = 2.81 J cm−3 and an efficiency of η = 90.8% under an external electric field of 480 kV cm−1. Subsequent tests revealed that the introduction of SBMN not only increased the band gap and conduction activation energy of the material, leading to an increase in BDS, but also promoted the formation of polar nanoregions (PNRs) which contributed to boosted energy efficiency, resulting in a significant enhancement in the energy storage performance of BST ceramics. [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon-based materials have a broad range of applications. Among various carbon-based materials, reduced graphene oxide (rGO) is one of the facile options for supercapacitor (SCs) fabrication. The main reason is that it offers excellent conductance and enhanced surface redox reactivity. Therefore, there is a significant possibility that this material will boost the electrochemical efficiency of pseudocapacitive materials based on transition metals. Using the sonication route, we have synthesized NiO/CoFe 2 O 4 composite and decorated it with rGO. After structural and morphological analysis, the prepared electrode materials were subjected to electrochemical energy storage efficiency studies. The obtained data showed that the NiO/CoFe 2 O 4 @rGO exhibited a higher specific capacitance of 911.25 Fg-1 as compared to other electrode materials (such as NiO/CoFe 2 O 4 , NiO, and CoFe 2 O 4). Moreover, it was observed that NiO/CoFe 2 O 4 @rGO has low equivalence series resistance (ESR) as 0.29 Ω, in comparison to NiO/CoFe 2 O 4 , NiO, and CoFe 2 O 4. The enhanced conductivity of rGO and the good crystallinity of NiO and CoFe 2 O 4 are responsible for the excellent efficiency of the NiO/CoFe 2 O 4 @rGO electrode material. According to the obtained results, the NiO/CoFe 2 O 4 @rGO nanocomposite is an effective capacitive material for supercapacitors fabrication. [Display omitted] [ABSTRACT FROM AUTHOR]

Lead-free relaxor ferroelectrics are useful in energy storage applications. In particular, BaTi 2 O 5 -based dielectric materials may have great potential for such applications. In this study, polycrystalline Ba 0.95 Sr 0.05 Ti 2 O 5 - x La (BST2- x La) ceramics were synthesized using a standard solid-state reaction method with as-prepared nanoparticles prepared via a modified Pechini polymeric precursor method. The structural and electrical properties of the BST2- x La ceramics were systematically investigated using a series of measurements. The phase analysis results confirm that La3+ is a donor dopant that replaced Ba2+ sites in the structure, which results in a decrease in oxygen vacancies to maintain charge neutrality. The intrinsic electronic conduction mechanism for electrical conductivity was evaluated from the fitted activation energy based on the Arrhenius equation. The relaxor ferroelectric behaviour and energy storage density and efficiency are improved by the addition of a small amount of lanthanum (<3.6 mol%) because of the charge and ionic radius mismatch in the structure. These results suggest that lanthanum can effectively optimise the relaxor ferroelectrics of BST2- x La ceramics, which have promising potential as energy storage materials. • Pure monoclinic-phase polycrystalline BST2- x La ceramics were synthesized. • La3+ acted as a donor dopant in the structure. • Mechanism of intrinsic electronic conduction in the ceramics was deduced. • La3+ could optimise the relaxor ferroelectric properties of BST2- x La ceramics. • The energy storage density and efficiency were improved at small values of x. [ABSTRACT FROM AUTHOR]