Low Energy Loss Research Articles

High energy storage properties for dielectric composite by asymmetric three-layer films design

Polymer dielectrics are extensively studied for applications in electronics pulsed power systems owing to their excellent processability, high breakdown strength and low energy loss. To synergistically achieve high energy density and high discharge efficiency, we report an asymmetric three-layer all-polymer composite, which consists of a mixture of P(VDF-HFP) and P(St-MMA) as an intermediate layer sandwiched between a linear polymer P(St-MMA) dielectric layer and a nonlinear polymer P(VDF-HFP) dielectric layer. The results of the study showed that a high efficiency of 94.14 % and a high energy discharge density of 14.86 J/cm3 were achieved concurrently. In this case, the linear dielectric layer provides high energy efficiency, and the high energy density is provided by the nonlinear layer dielectric layer. In particular, the middle layer can effectively balance the electric field distribution, which improves the breakdown strength and increases the energy density. The structural design of asymmetric three-layer all-polymer films provides an effective way to realize high-performance dielectric energy storage materials.

Effect of uneven inflow on hydrodynamic performance of bulb turbine

Abstract Bulb turbine unit is characterized by its low head, large discharge, and short flow passage. The guiding wall separating the power house section from the flood discharge section may cause uneven inflow before its neighbor units when the power house section is located off the river’s mainstream. In this study, selecting a bulb turbine hydropower station in China as the subject, we establish a three-dimensional CFD model that contains the full flow passage of the turbine unit and partial upstream reservoir, to analyze the effects of uneven inflow on the hydrodynamic performance of the bulb turbine. The results show that under this power station layout, flow separation occurs on the left side of the guiding wall, resulting in a low pressure zone and causing the flow in a three-dimensional vortical pattern. The low pressure and flow energy loss lead to the reduction of the neighbor units’ head, causing the discharge decreasing, and the output cannot reach the expectations. This situation can be improved by shortening the guiding wall, indicating that the unit’s performance is strongly related to the hydraulic structure arrangement. The results can provide some references for the design and operation of the related project.

0.16BaFeO3-0.84MgFe2O4 hexa-spinel composited ferrites with enhanced magneto-dielectric properties for miniaturized high-frequency antennas

we deeply dived multi-phase-based 0.16BaFeO3-0.84MgFe2O4 ferrite for VHF antennas. The structural and magneto-dielectric properties synthesized at various temperatures (1100 °C, 1125 °C, 1150 °C and 1175 °C) were investigated. The results demonstrated the coexistence of hexagonal and cubic spinel phases. Microstructure analysis indicated higher temperature induced lager grain size and denser structure. Meanwhile, both the saturation magnetization (from 28 to 25 emu/g) and coercivity (19–5 Oe) decreased. In addition, real permeability (μ′) and permittivity (ε′) arose at higher temperature, promising equivalent permeability and permittivity. What's more, relatively low magnetic and dielectric losses (tanδμ ∼10−2 to 10−3 and tanδε ∼10−3 to 10−4) promote low energy loss. Finally, a miniaturized antenna with relative bandwidth of 14.6 %, peak gain of 0.98 dB, and radiation efficiency of 74.6 % was simulated based on the processed ferrites. In conclusion, the presented investigation greatly improves the magneto-dielectric response, which paves the way to realize high performance in VHF antenna application.

Endothermic Charge Separation Occurs Spontaneously in Non-Fullerene Acceptor/Polymer Bulk Heterojunction.

Organic photovoltaics (OPVs) based on non-fullerene acceptors (NFAs) have achieved a power conversion efficiency close to 20%. These NFA OPVs can generate free carriers efficiently despite a very small energy level offset at the donor/acceptor interface. Why these NFAs can enable efficient charge separation (CS) with low energy losses remains an open question. Here, the CS process in the PM6:Y6 bulk heterojunction is probed by time-resolved two-photon photoemission spectroscopy. It is found that the CS, the conversion from bound charge transfer (CT) excitons to free carriers, is an endothermic process with an enthalpy barrier of 0.15eV. The CS can occur spontaneously despite being an endothermic process, which implies that it is driven by entropy. It is further argued that the morphology of the PM6:Y6 film and the anisotropic electron delocalization restrict the electron and hole wavefunctions within the CT exciton such that they can primarily contact each other through point-like junctions. This configuration can maximize the entropic driving force.

A Single Component, Single Layer Flexile Foam Evaporator with the Higher Efficiency for Water Generation.

One of the greenest and promising ways to solve the problem of freshwater crisis is surface solar steam generation from seawater. A great number of photothermal materials with multi-component and multi-layered delicate yet complex structures often suffer from either low evaporation rate or high energy loss. Here, this work presents a single component foam evaporator with steam generation rate of up to 4.32kg m-2 h-1 under 1 sun irradiation. The evaporator is constructed from an aniline oligomer as a single light-absorbing component, covalent linked with polyethylene glycol to form a monolithic polymer foam. Floating on the seawater, the foam has absorbance of 99.5% over the entire solar spectral range and low thermal conductivity (0.0077W K-1m-1) that effectively retains heat in the material and at the interface. After 3 months of continuous outdoor natural sunlight irradiation, the evaporator maintains a stable and durable evaporation rate. Moreover, the materials have good mechanical properties (7.48MPa young's modulus and 57.38% elongation at break) and excellent chemical resistance in 10 common organic solvents and aqueous solutions of pH = 1 to 14. This study provides a new system and strategy for desalination, steam power generation, treatment of polluted water and sewage, etc.

A strategy to assess the use-phase carbon footprint from energy losses in electric vehicle battery

The electric vehicles are not completely emission-free. The vehicles consume power and the power generation processes involve carbon emissions, resulting in indirect vehicle usage carbon emissions. A use-phase carbon emissions assessment can help electric vehicle designers and manufacturers analyze the onboard carbon footprint and mitigate vehicle-related carbon emissions through energy consumption optimization. In this article, we focus on the use-phase carbon footprint based on the energy losses in electric vehicle battery packs. A battery pack energy loss model is established to examine the carbon footprint of four main subsystems of the battery pack, including the energy storage system, thermal management system, and battery junction box. We use the proposed method to evaluate the battery pack use-phase carbon emissions in four different cities from four main continents. The results show that the highest emissions appear in Tokyo (436.2 kgCO2) due to the relatively high greenhouse gas factor on the grid, the London has the lowest 207.5 kgCO2 emissions due to the massive adoption of sustainable energy during power generation. With a similar high greenhouse gas factor, but Sydney shows lower emissions (347.5 kgCO2) compared to Tokyo, which illustrates the closer the annual average temperature to the battery suitable operation range, the lower energy loss happens inside the battery pack due to the low thermal management load and resistance energy loss in the cells. This electric vehicle has the highest energy loss rate (20.8%) in New York, 343.6 kgCO2 emissions, and the highest thermal management system energy losses show the high seasonal temperature difference causing the high thermal management load to maintain the battery temperature. The proposed method can be used for different battery pack configurations and vehicle uses, providing researchers with a robust and versatile use-phase carbon emissions assessment strategy.

Research on Energy Loss of Optimization of Inducer–Impeller Axial Fit Dimensions Based on Wave-Piercing Theory

With the development of modern fluid machinery, the energy density of pumps is gradually being improved, and at the same time, higher demands are being placed on the cavitation performance, hence the introduction of the inducer and centrifugal impeller to form a dynamic–dynamic series structure. However, there are strict constraints on the axial size of pumps in fields such as firefighting and aerospace. The traditional empirical formula no longer satisfies the need to fit the axial dimensions between the induced wheel and the impeller at high velocities. Therefore, based on the wave-piercing theory, the drag reduction coefficient is introduced to explore the optimal axial fit size from the perspective of energy characteristics. This paper focuses on the influence of the inducer’s wake on the energy characteristics of downstream impellers, and conducts the following research: by adjusting the axial matching dimensions between the upstream inducer and the centrifugal impeller in the initial model, ten sets of axial distance models with matching dimensions of KD are designed, and the drag reduction coefficient is embedded to determine the optimal axial distance. The results show that the optimal axial distance is 0.2D, which is far lower than the axial distance value of 0.42D obtained from the traditional empirical formula for axial matching dimensions. Meanwhile, this paper uses tangential velocity, the inlet flow angle of the impeller, entropy production theory, and other indicators to analyze the internal energy loss of the high-speed vehicular fire pumps one by one. All of them confirm that the impeller in the high-speed vehicular fire pump has the lowest energy loss and optimal performance at an axial distance of 0.2D. Specifically, at this axial distance, the head can reach 259 m, and the hydraulic efficiency is as high as 83.62%. Thus, the feasibility of determining the axial placement of the impeller using the drag coefficient is validated. This research provides new insights into determining the axial coordination dimensions between the inducer and the impeller.

Design of Photovoltaic Systems in Industrial Electrical Systems Considering Power Quality

This paper presents a comprehensive design methodology for photovoltaic systems (PVS) integrated into industrial electrical systems (IES), with a specific focus on preserving power quality (PQ). The 10-step methodology, ranging from initial interviews to detailed technical, energy, and economic assessments, is novel for its multi-factorial approach that combines an Excel application with ETAP software, prioritizing considerations for PQ. Evaluation across four scenarios demonstrated varying outcomes. In the worst-case technical and energy scenario, PVS installation on Point of Common Connection without PQ mitigation led to significant increases in harmonics and no reduction in energy consumption. Conversely, the best technical and energy scenario involved distributing PVS across load buses with PQ mitigation, resulting in a 5% reduction in energy consumption and 27% lower energy losses. The economic evaluation indicated a three-year payback period in all scenarios, primarily attributed to increased costs for PQ problem mitigation equipment. It was also observed that reducing losses and energy consumption limits the economic benefits of installing PVS in IES. This methodology serves as a valuable guide for designing PVS in IES, incorporating technical, energy, economic, and PQ considerations.

Voltage-assisted 3D printing of polymer composite dielectric films with low energy loss and high energy storage density

PVDF-based polymers have garnered significant attention in the field of high-power density electrostatic capacitors due to their exceptional dielectric strength. However, their practical applications are constrained by low charge-discharge efficiency (η) and energy storage density (Ue), which stem from high ferroelectric relaxation and low breakdown strength (Eb). Here, a hydrogenated glassy polymer poly(styrene-methyl methacrylate-methylallyl alcohol) (PSMA) is designed and synthesized to be homogeneously distributed in PVDF through voltage-assisted 3D printing-hot pressing, resulting in a flexible composite film. The findings demonstrate that PSMA, rich in hydrogen bonds and high modulus strength, effectively mitigates the ferroelectric phase transition of PVDF to enhance η. Additionally, the voltage-assisted 3D printing process induces an entropy gain mechanism, facilitating the uniform distribution of the two phases and enhancing the interfacial properties for enhancing Eb. Remarkably, the study achieves prominent growth in energy storage performance, with Ue and η reaching 18.1 J/cm3 and 80 % at 525 MV/m, respectively. These remarkable results highlight the potential of 3D printing technology in enhancing the energy storage performance of PVDF-based dielectrics.

Asymmetric non-fused ring acceptor with low energy loss for efficient organic solar cells

Non-fused ring acceptors (NFRA) show high structural diversity with low synthesis complexities and high cost-effectiveness, which holds the potential to boost the performance of organic solar cells (OSCs). For OSCs, it is crucial to broaden the absorption range while minimizing energy loss. One strategy involves creating acceptors with asymmetric structures. However, to date, there have been relatively few reports on NFRA with asymmetric backbones. Here, we designed a new NFRA molecule UF-ATT-2F with asymmetric π-bridges (thieno [3,2-b] thiophene and thiophene) and studied its performance in OSC. Compared with two symmetric reference molecules UF-T-2F and UF-TT-2F, the device based on the asymmetric acceptor UF-ATT-2F exhibits much lower energy loss, more appropriate phase separation scale and broader absorption range, consequently achieving a higher open-circuit voltage (Voc) exceeding 0.9 V and a decent PCE of 13.26 %. This work demonstrates that incorporating asymmetric π-bridge is an effective strategy for the design low-energy loss and high-performance organic photovoltaic acceptor.

Co-hydrolysis of TEOS and DDS to obtain a modified hydrophobic SiO2 insulation layer for FeSiBC amorphous magnetic powder core with low energy loss

The hysteresis effect and eddy currents caused by alternating magnetic fields greatly impede the improvement of the working efficiency and performance stability of soft magnetic powder cores. In this work, modified hydrophobic SiO2 nanoparticles were prepared by tetraethyl orthosilicate (TEOS) and dimethyl-diethoxy-silane (DDS) as co-precursors through sol–gel methods. The effect of different proportions of DDS and TEOS on the amorphous magnetic powder cores performance was studied. It was demonstrated that the insulation layer in DDS and TEOS co-precursors hydrolyzed composite powders exhibited more uniform distribution compared with TEOS hydrolyzed alone counterpart. The introduction of methyl groups reduced the accumulation of hydrolysis intermediates on the surface of FeSiBC powders. Furthermore, the addition of DDS reduced eddy current loss significantly with a low hysteresis loss. The total energy loss of the DDS and TEOS co-hydrolysis powder core were reduced by 16.1 % and 7.7 % at 1 MHz, 0.05 T compared to the uncoated powder core and the TEOS hydrolysis alone counterpart, respectively. The presented results provide insights into improving the application range and energy utilization efficiency for the magnetic powder cores.

N vacancy and self-enhancement induced high anodic electrochemiluminescence of 3D g-C3N4 for sensitive staphylococcus aureus analysis

Here, 3D g-C3N4 with dense N vacancy in its 3D porous interconnected open-framework was synthesized, and the co-reactive 3-(dibutylamino)propylamine (DBAPA) was further covalently coupled onto the surface, resulting in a strong self-enhanced anodic electrochemiluminescence (ECL). Through introduction of high-density N vacancy, for the obtained 3D g–C3N4–NV, the band gap was broadened and the electrical conductivity was enhanced, realizing an obvious ECL improvement. Moreover, after the covalent binding of co-reactive DBAPA, the obtained 3D g–C3N4–NV-DBAPA exhibited a more intensive self-enhanced ECL signal due to the higher co-reaction efficiency originated from shorter electron transfer distance and lower energy loss. Based on the high initial signal of the proposed 3D g–C3N4–NV-DBAPA, a sensitive ECL biosensor with signal “on-off” was fabricated in assistance with multiple horizontal ordered hybridization chain reaction (HO-HCR). Through orderly fixing the reacted DNA chains on the Y-shape DNA structure on the electrode could effectively decrease diffusion process and improve the reaction efficiency of HCR process, resulting in the formation of numerous long horizontal double-strand DNA that could immobilize abundant ferrocene-doxorubicin (Fc-Dox) with ECL quenching effect. Meanwhile, compared to the traditional vertical HCR, the HO-HCR could make the quench reagent closer to the ECL emitter on the electrode surface and obtain a more effective quenching effect to enhance the sensing sensitivity. As a result, the proposed ECL biosensor archived the sensitive measurement of staphylococcus aureus with a detection limit of 10.3 aM.

Broadband and highly efficient asymmetric optical transmission through periodic Si cylinder arrays on the dielectric substrates

Asymmetric optical transmission is widely used in various fields due to the manipulation of light direction. This work theoretically investigates highly efficient and polarization-independent asymmetric optical transmission in the broadband wavelength through the periodic Si cylinder arrays on the dielectric substrates. The simulated results show that the maximum asymmetric optical transmission can reach 0.894, with high forward transmission of 0.898 and nearly zero backward transmission of 0.004 at the wavelength of 540 nm. The structure also exhibits excellent light-trapping characteristics with low energy loss and anti-reflection. The formation of asymmetric optical transmission comes from the diffraction which contributes differently to the transmission under forward and backward illuminations. Furthermore, asymmetric optical transmission in the structure is insensitive to the refractive index of the dielectric substrate and the height of the Si cylinder, and the wavelength position of the maximum asymmetric optical transmission is only sensitive to the height of the Si cylinder. This work proposes a multifunctional nanostructure and provides guidelines for designing practical devices that utilize asymmetric optical transmission.

Structural phase coexistence enhances the energy storage density of (Bi0.5Na0.5)0.8Ba0.2Ti1-ySnyO3 lead-free ceramics

In the present study, BaSnO3 was introduced into polycrystalline NBT-BT ferroelectric ceramics and conducted a comprehensive investigation into the structural, dielectric, ferroelectric, and energy storage characteristics of the (Bi0.5Na0.5)0.8Ba0.2Ti1-ySnyO3 (BNBTS) ceramics. The coexistence of structural phases P4mm and Amm2 was observed through Rietveld refinement and also confirmed by Raman analysis. The formation energy decreases with an increase in substitution concentration favouring the formation of the orthorhombic phase. The SEM analysis revealed a denser microstructure characterised by smaller grain sizes, which favourably enhances energy storage density. Furthermore, Raman spectroscopic analysis unveiled a softening of Ti–O bonds, indicating the emergence of macroscopic relaxor behaviour. Dielectric studies provided evidence of a transition from ferroelectric to relaxor behaviour, an observation further confirmed by P-E loop measurements. This transition can be linked to the partial substitution of Sn4+ ions for Ti4+ ions, disrupting the ferroelectric long-range order within the matrix phase. Notably, the polarization-electric field (P-E) loop of BNBTS2 ceramics exhibited a substantial value of polarization (Ps) 30 μC/cm2 with a reduced value of remnant polarization (Pr) 2.29 μC/cm2. These characteristics contributed to the achievement of higher energy recovery (Wrec) and lower energy loss (Wloss) values, measuring 1.184 J/cm3 and 0.142 J/cm3, respectively, with a notable efficiency of 88.8%. Consequently, the system of ternary ceramics demonstrates promise as a potential option for energy storage ceramics among NBT-BT-based materials.

C-Shape or S-Shape? The Molecular Geometry Control of Fused-Ring Nonfullerene Acceptors for Lower Energy Loss in Organic Solar Cells

C-Shape or S-Shape? The Molecular Geometry Control of Fused-Ring Nonfullerene Acceptors for Lower Energy Loss in Organic Solar Cells

Applications of 2D semiconductor materials in electronics and optoelectronics

Due to the demand for the higher performance of electronic and optoelectronic devices, the research of 2D semiconductor materials is very important nowadays. Because of the excellent electronic and optoelectronic properties of 2D semiconductor materials can be applied in many fields. This article mainly introduced the preparation, properties and applications of 2D semiconductor materials. The applications in electronics and optoelectronics are mainly discussed, such logic gates, field effect transistors light emitting diodes and high responsivity photodetectors. Compared to traditional semiconductor materials, 2D semiconductor materials have higher mobility and energy efficiency, leading to higher responding speed and lower energy loss. The flexibility of these materials also makes wearable electronic devices possible. However, they are still short in stability and immature in preparation. Future studies should focus more on the stability and preparation of 2D semiconductor materials and9 make the massive production and application of such high-performance materials plausible.

Small molecule donor third component incorporating thieno[3,2-b]thiophene unit enables 19.18% efficiency ternary organic solar cells with improved operational stability

The rational design of the third component to enhance the efficiency and stability of organic solar cell (OSC) is a critical and challenge. Herein, a thieno[3,2-b]thiophene (TT) substituted wide-bandgap small molecule donor BTTC, was designed, synthesized and incorporated into the state-of-the-art PM6:L8-BO binary to construct ternary OSC. The rigid side chain and planar molecule skeleton enables strong crystallinity and complementary absorption with binary system. The introduction of BTTC enhanced the molecular packing, fibril-like film and preferred vertical phase separation, yielding balanced and higher charge transport, more efficient exciton dissociation and suppressed charge recombination. Besides, lower energy loss was attained and thus leading to higher open-circuit voltage (VOC). Consequently, the introduction of BTTC achieved the highest efficiency of 18.8% along with extended operational stability. Furthermore, replacing L8-BO to BTP-eC9 further boosted the ternary PCE to 19.18%, standing one of the best charge management in ternary OSC. This work presents efficient rigid side chain substitution strategy to construct the third component of small molecule donor for high performance ternary OSCs with comprehensively improved photovoltaic parameters. This strategy broadens the selection of guest materials toward realizing the actual commercial application of OSCs.

Design and Synthesis of Dibenzothiadiazolopyrrolothiophene (DBTPT)‐Based Acceptors for Efficient Organic Photovoltaic Cells

AbstractThe central core in non‐fullerene acceptors (NFAs) plays a crucial role in determining the efficiency of organic photovoltaic (OPV) cells. To further advance the development of OPV cells, it is crucial to synthesize novel central cores for constructing high‐performance NFAs. Here, dibenzothiadiazolopyrrolothiophene (DBTPT) is introduced, a ladder‐type [1,2,5]thiadiazolo[3,4‐e]indole‐fused pentacyclic thiophene unit, into photovoltaic materials. By employing the DBTPT unit as the rigid molecular backbone and modifying the side chain of the thiophene π‐bridge, two new acceptor‐π‐acceptor’‐donor‐acceptor’‐π‐acceptor (A‐π‐A'DA’‐π‐A)‐type acceptors (T6 and T9) are synthesized. The effects of lateral alkyl and alkoxy side chains on the optoelectronic properties, charge transport, and molecular packing order are systematically investigated. When blended with polymer donor Poly[(2,6‐(4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1,2‐b:4,5‐b']dithiophene))‐alt‐(5,5‐(1',3'‐di‐2‐thienyl‐5'7'‐bis(2‐ethylhexyl)benzo[1',2'‐c:4',5'‐c']dithiophene‐4,8‐dione))] (PBDB‐T), the blend film based on T9 with alkoxy side chains shows favorable molecular stacking and phase separation, resulting in excellent charge transfer performance. Benefiting low energetic disorder, PBDB‐T:T9‐based cell achieves an efficiency of 12.6% with a markedly low energy loss of 0.568 eV. The preliminary results demonstrate that the DBTPT unit has great potential for the construction of novel NFAs for high‐performance OPV cells.

Efficient Ternary Organic Solar Cells with Suppressed Nonradiative Recombination and Fine-Tuned Morphology via IT-4F as Guest Acceptor.

The large open circuit voltage (VOC) loss is currently one of the main obstacles to achieving efficient organic solar cells (OSCs). In this study, the ternary OSCs comprising PM6:BTP-eC9:IT-4F demonstrate a superior efficiency of 18.2 %. Notably, the utilization of the medium bandgap acceptor IT-4F as the third component results in an exceptionally low nonradiative recombination energy loss of 0.28 V. The desirable energy level cascade is formed among PM6, BTP-eC9, and IT-4F due to the low-lying HOMO and LUMO energy levels of IT-4F. More importantly, the VOC of PM6:BTP-eC9:IT-4F OSCs can reach as high as 0.86 V, which is higher than both binary OSCs without sacrificing JSC and FF. Besides, this strategy proved that IT-4F can not only broaden the absorption range but also work as a morphology modifier in PM6:BTP-eC9:IT-4F OSCs, and there also exists efficient energy transfer between BTP-eC9 and IT-4F. This result provides a promising way to suppress the nonradiative recombination energy loss and realize higher VOC than the two binary OSCs in ternary OSCs to obtain high power conversion efficiencies.

Supercritical foaming of novel poly(ether‐b‐amide) elastomer and compression property characterization

AbstractLightweight foam made of poly(ether‐b‐amide) (PEBA) elastomer has been widely used in sport shoes due to its superior rebounding and supporting properties. Novel PEBA with polyamide 1012 as hard segments and poly(tetramethylene oxide) (PTMO) as soft segments was foamed by supercritical CO2. The influence of foaming process parameters, that is saturation temperature, pressure on the morphology of cellular structure was systematically studied by scanning electron microscopy (SEM) and wide‐angle x‐ray diffraction (WAXD). By controlling the viscoelastic behavior of PEBA at certain temperatures and pressures, foams with low density and energy loss coefficient can be fabricated. The cell density of 4.5 × 109 cells/cm3 and expansion ratio of 16.0 of the foams can be obtained respectively. Cyclic compression performance of foams was systematically studied. For the foams with the highest expansion ratio, the energy loss coefficient of 11.9% in the first cycle and 3.5% after equilibrium were observed, which were less than those of former reported PEBA foams. The relationship between the Young's modulus and expansion ratio is in line with the Gibson–Ashby relationship.