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Micro energy storage devices (MESDs) have emerged as promising energy providers for micro applications due to their integrated performance. However, the limited cycle life and low power density of microbattery, and low energy density of microsupercapacitor have consistently impeded their broader practical implementation. Herein, to obtain a MESD with a long cycle life, excellent power density, and superior energy density, a novel micro battery‐supercapacitor hybrid (MBSH) device is fabricated. Two types of 3D microelectrodes are fabricated, namely, a nanowire network anode based on PEDOT‐TiON and a porous cathode based on Ni(OH)2. Benefiting from the unique hydrophobic characteristics of the PEDOT layer, high electrical conductivity of TiON, and high conductivity, and abundant ion diffusion channels of network microstructure, PEDOT‐TiON NW microelectrodes demonstrate exceptional cycling stability by retaining 70% of their capacity after 40 000 cycles. The achieved MBSH exhibits an extended voltage window ranging from 0 to 1.9 V, impressive power density of 77.5 mW cm−2, and a superior energy density of 55.6 µWh cm−2. Furthermore, it maintains a remarkable capacity retention rate of 71.6% even after undergoing 30 000 cycles. This innovative design paves the way for the developing of high‐performance microdevices with superior electrochemical properties. [ABSTRACT FROM AUTHOR]

Optimized sodium ion battery (SIB) carbon anodes with high stability supporting high power densities are a much‐needed material class and therefore intensively researched. The optimum graphitization degree to accommodate sodium ions, while providing high conductivity, as well as the influence of particle size distribution or pore sizes on the performance of carbon anodes, is one of the most discussed topics in this field. While a lot of studies have been published discussing these questions, the convoluted nature of these parameters, originating from material synthesis constraints, usually prevents their independent optimization. Based on Mesoporous N‐doped Carbon Nanospheres (MPNC) as model carbon material systems, the graphitization temperaturefor spherical particles with a monomodal particle size distribution (≈280 nm) and a narrow pore size distribution (≈30 nm) is optimized for faradaic sodium ion storage (plateau capacity) and electrodes with a very high power density of 2680 W kg−1 at 1000 mA g−1 and a remarkable capacity retention over 2000 cycles of 86 %, only losing 0.04 % of its specific capacity per cycle, are demonstrated. [ABSTRACT FROM AUTHOR]

A compact cell structure is highly desirable for next-generation high-power-density proton exchange membrane (PEM) fuel cell (>9.0 kW L−1). A novel integrated bipolar plate (BP) – gas diffusion layer (GDL) structure utilizing porous material is a promising configuration, which not only improves output power due to the reduced transport resistance but also reduces cell thickness. Herein, we propose a structured mesh material with gradient surface wettability for this cell structure, which is characterized by an ordered skeleton in the three-dimensional (3D) space with high structure design flexibility. It is experimentally found that the structured mesh material shows higher performance than serpentine and parallel flow fields. Meanwhile, 3D modeling work on an automobile fuel cell (cell area: 245.76 cm2) with the distribution zones of dot matrix structure for hydrogen, air and coolant flow, is conducted, and it is found that the structured mesh material effectively decreases the concentration and electric ohmic losses in comparison with the traditional "BP/flow field + GDL" structure, improving power density with uniform distribution characteristics. Moreover, the gradient wettability on the mesh surface helps promote the water detach the GDL and hold the residual liquid water in the top region, optimizing the water management. [ABSTRACT FROM AUTHOR]

In recent years, sodium-ion capacitors have attracted attention due to their cost-effectiveness, high power density and similar manufacturing process to lithium-ion capacitors. However, the utilization of oxide electrodes in traditional sodium-ion capacitors restricts their further advancement due to the inherent low operating voltage and electrolyte consumption based on their energy storage mechanism. To address these challenges, we incorporated Zn, Cu, Ti, and other elements into Na0.67Ni0.33Mn0.67O2 to synthesize P2-type Na0.7Ni0.28Mn0.6Zn0.05Cu0.02Ti0.05O2 with a modulated entropy and pillaring Zn. Through the synergistic interplay between the interlayer pillar and the entropy modulation within the layers, the material exhibits exceptional toughness, effectively shielding it from detrimental phase transitions at elevated voltage regimes. As a result, the material showcases outstanding kinetic properties and long-term cycling stability across the voltage range. By integrating these materials with hierarchical porous carbon nanospheres to form a "rocking chair" sodium-ion capacitor, the hybrid full device delivers a high energy density (171 Wh·kg−1) and high power density (5245 W·kg−1), as well as outstanding cycling stability (77% capacity retention after 3000 cycles). This work provides an effective material development route to realize simultaneously high energy and power for next-generation sodium-ion capacitors. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have emerged as a promising technology to harvest electrical energy from natural motions such as human movement, wind, and water flow. Although TENGs show significant potential in small-scale applications, developing large-scale TENGs capable of generating high power remains a significant challenge. Several factors that can affect the performance of large-scale TENGs are being investigated to overcome this challenge, including the size and configuration of dielectric materials. This study optimizes dielectrics regarding surface area, thickness, and multicell configuration to improve harvested electrical power density in large-scale TENGs. In the studies, glass fiber was used as the positive dielectric, and multipurpose white silicone was used as the negative dielectric because of their high tribo-potential, durability, and easy accessibility. In the size optimization phase, dielectric thicknesses and surface areas that provide the maximum power density were determined. Subsequently, horizontal and vertical multicell configurations were examined to efficiently integrate size-optimized dielectrics. The results reveal that large-scale TENGs with vertical multicell configurations can achieve high and usable energy density for electronics. The findings provide valuable insight into the development of large-scale TENGs with advanced power generation capabilities. [ABSTRACT FROM AUTHOR]

Simultaneously achieving high‐energy‐density and high‐power‐density is a crucial yet challenging objective in the pursuit of commercialized power batteries. In this study, atomic layer deposition (ALD) is employed combined with a coordinated thermal treatment strategy to construct a densely packed, electron‐ion dual conductor (EIC) protective coating on the surface of commercial LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode material, further enhanced by gradient Al doping (Al@EIC‐NCM523). The ultra‐thin EIC effectively suppresses side reactions, thereby enhancing the stability of the cathode‐electrolyte interphase (CEI) at high‐voltages. The EIC's dual conduction capability provides a potent driving force for Li+ transport at the interface, promoting the formation of rapid ion deintercalation pathways within the Al@EIC‐NCM523 bulk phase. Moreover, the strategic gradient doping of Al serves to anchor the atomic spacing of Ni and O within the structure of Al@EIC‐NCM523, curbing irreversible phase transitions at high‐voltages and preserving the integrity of its layered structure. Remarkably, Al@EIC‐NCM523 displays an unprecedented rate capability (114.7 mAh g−1 at 20 C), and a sustained cycling performance (capacity retention of 74.72% after 800 cycles at 10 C) at 4.6 V. These findings demonstrate that the proposed EIC and doping strategy holds a significant promise for developing high‐energy‐density and high‐power‐density lithium‐ion batteries (LIBs). [ABSTRACT FROM AUTHOR]

Simple and scalable production of micro-supercapacitors (MSCs) is crucial to address the energy requirements of miniature electronics. Although significant advancements have been achieved in fabricating MSCs through solution-based printing techniques, the realization of high-performance MSCs remains a challenge. In this paper, graphene-based MSCs with a high power density were prepared through screen printing of aqueous conductive inks with appropriate rheological properties. High electrical conductivity (2.04 × 104 S∙m−1) and low equivalent series resistance (46.7 Ω) benefiting from the dense conductive network consisting of the mesoporous structure formed by graphene with carbon black dispersed as linkers, as well as the narrow finger width and interspace (200 µm) originating from the excellent printability, prompted the fully printed MSCs to deliver high capacitance (9.15 mF∙cm−2), energy density (1.30 µWh∙cm−2) and ultrahigh power density (89.9 mW∙cm−2). Notably, the resulting MSCs can effectively operate at scan rates up to 200 V∙s−1, which surpasses conventional supercapacitors by two orders of magnitude. In addition, the MSCs demonstrate excellent cycling stability (91.6% capacity retention and ~100% Coulombic efficiency after 10,000 cycles) and extraordinary mechanical properties (92.2% capacity retention after 5000 bending cycles), indicating their broad application prospects in flexible wearable/portable electronic systems. [ABSTRACT FROM AUTHOR]

Enhancing the accessibility and utilization of active sites through mesopores in carbon anode materials is crucial for developing high‐power potassium‐ion hybrid supercapacitors (PIHCs). Here, a multiscale phase separation method combining block copolymer (BCP) microphase‐ and homopolymer (HP) macrophase‐separation is utilized to produce two model carbon materials with controlled mesopore orientation: open‐end (oe‐MCS) and closed‐end mesoporous carbon sphere (ce‐MCS). BCPs form identical cylindrical micelles, and HPs encapsulate these cylindrical micelles within spheres and control their orientations relative to the interface. This approach manipulates only the degree of mesopore openings in the MCS materials while maintaining all other factors at similar levels. Opening mesopores in carbon anode materials primarily enhances K+ adsorption capacity, reduces K+ diffusion length, and improves ion transport. Thus, oe‐MCS anode exhibits a higher specific capacity with a significant capacitive‐controlled contribution. The resulting PIHC device displays maximum energy and power densities of 103 Wh kg−1 and 12 300 W kg−1, respectively, along with capacity retention of 86.1% after 20 000 cycles at 2.0 A g−1. This study significantly advances the understanding of mesopore design to improve capacitive K+ storage in hard carbon materials, paving the way for the development of high‐power PIHCs. [ABSTRACT FROM AUTHOR]

Herein, conductive and stable partially fluorinated multi-cationic alkaline membrane (AM) has been reported by macromolecular modification of poly (vinylidene fluoride) (PVDF) and chemical grafting of vinyl benzyl chloride (VBC). Quaternization was achieved using different amines, to control the concentration of quaternary ammonium (QA) groups. Different multi-cationic AMs were analysed by their structural (1H NMR and FT-IR) and morphological properties, ion-exchange capacity (IEC), water uptake (WU), alkaline conductivity (κ m ), and stabilities (mechanical, chemical, and thermal). Due to presence of multi cationic groups and thus steric hindrance, reported membranes were robust in alkaline medium. Single-cell anion exchange membrane fuel cell (AMFC) assembled with Tri-amino-VBC-g-PVDF membrane, exhibited relatively high performance (open circuit voltage (OCV): 1.03 V, peak power density: 244.0 mW cm−2 at 400.0 mA cm−2), in compare with other AMs reported in the literature. It was observed that AMFC performance was strongly depends on cationic group density, and present study explored the utilization possibility of partially fluorinated polymer matrix with multi-cationic groups for long lifetime during AMFC application. [Display omitted] • High performance partially fluorinated multi-cationic alkaline membrane. • Alkaline membrane robust for Hofmann β -elimination and SN 2 reactions. • 96.34% remained conductivity after alkali treatment at 80 °C for 768 h. • 244.0 mW cm−2 maximum power density at 400.0 mA cm−2. [ABSTRACT FROM AUTHOR]

In response to the need for smaller and lighter power supply equipment, there has been a push towards higher power density in current power electronic converters. This development aligns well with the requirements of photovoltaic grid‐connected inverters. Among various passive filters utilized in these inverters, the LCL filter stands out as a popular choice. Nevertheless, it should be noted that traditional LCL filters have limited core utilization and exhibit significant redundancy. In view of the above problems, this paper proposes a magnetic integrated passive filter based on ripple transfer technology and carries out volume optimization design. Compared to the conventional LCL filter, the magnetic integrated passive filter offers a reduction in size and weight while preserving its capability to ripples attenuate. Finally, a laboratory prototype with a rated power of 2 kW is built to verify the effectiveness of the proposed magnetic integrated passive filter. [ABSTRACT FROM AUTHOR]

This study presents a thermoset moulding compound designed for electrical machines with high power densities. The compound reduces residual stresses induced by the difference in thermal expansion during use and by shrinkage in the compound during the manufacturing process. To reduce the internal stresses in the compound, in the electrical sheet lamination and at their interface, first the moulding's coefficient of thermal expansion (CTE) must match that of the lamination because the CTE of the electrical sheets cannot be altered. Second, the shrinkage of the compound needs to be minimized because the moulding compound is injected around a prefabricated electrical sheet lamination. This provides greater freedom in the design of an electric motor or generator, especially if the thermoset needs to be directly bonded to the electrical sheet. The basic suitability of the material for the injection moulding process was iteratively optimised and confirmed by spiral flow tests. Due to the reduction of the residual stresses, the compound enables efficient cooling solutions for electrical machines with high power densities. This innovative compound can have a significant impact on electric propulsion systems across industries that use laminated electrical sheets. [ABSTRACT FROM AUTHOR]

High‐power‐density rechargeable batteries are highly indispensable for power‐intensive application scenarios, such as vehicle start‐stop system and grid‐level frequency regulation. However, realizing high‐power‐density alkali‐ion batteries is challenging especially at low temperatures, as undesirable alkali metal plating tends to occur more easily on the anode surface due to the increased electrochemical impedance and polarization. Herein, a low‐temperature, high‐power‐density rechargeable Na3V2(PO4)3 ||hard carbon (HC) sodium‐ion full battery without Na plating is realized by electrolyte regulation. The designed high‐solvation‐entropy electrolyte enables a high ionic conductivity of 13.87 mS cm−1 at −40 °C. More importantly, the enhanced contact‐ion pairs solvation structure induces an anion‐derived, thin, NaF‐rich solid electrolyte interface (SEI) on HC anodes with low interfacial resistance to ensure facile Na+ diffusion through the SEI. Consequently, the assembled sodium‐ion full battery demonstrates a record‐high power density of 1132.31 W kg−1 (with an energy density of 61.94 Wh kg−1) at −40 °C and 13372.56 W kg−1 (132.83 Wh kg−1) at 25 °C (based on total mass of the active materials on anode and cathode). This work will expedite the development of sodium‐ion batteries for power‐intensive applications in extreme environments. [ABSTRACT FROM AUTHOR]

Rechargeable Zn–air batteries (ZABs) are considered highly competitive technologies for meeting the energy demands of the next generation, whether for energy storage or portable power. However, their practical application is hindered by critical challenges such as low voltage, CO2 poisoning at the cathode, low power density, and poor charging efficiency Herein, a rechargeable hybrid alkali/acid Zn–air battery (h‐RZAB) that effectively separates the discharge process in an acidic environment from the charging process in an alkaline environment, utilizing oxygen reduction reaction (ORR) and glycerol oxidation reaction (GOR) respectively is reported. Compared to previously reported ZABs, this proof‐of‐concept device demonstrates impressive performance, exhibiting a high power density of 562.7 mW cm−2 and a high operating voltage during discharging. Moreover, the battery requires a significantly reduced charging voltage due to the concurrent utilization of biomass‐derived glycerol, resulting in practical and cost‐effective advantages. The decoupled system offers great flexibility for intermittently generated renewable power sources and presents cost advantages over traditional ZABs. As a result, this technology holds significant promise in opening avenues for the future development of renewable energy‐compatible electrochemical devices. [ABSTRACT FROM AUTHOR]

Recently through the synergetic utilization of triboelectrification, electrostatic induction, and electrostatic discharge, a novel dual‐functional triboelectric nanogenerator (DF‐TENG) has been developed, which can not only generate a motion‐responsible alternating current/ direct current output but also provide a higher performance compared to traditional TENGs. However, further improvements in performance and lifespan are crucial and remain challenging for the future large‐scale application of this new‐type TENG. Herein, a novel bioinspired self‐lubricating prototype is presented (BS‐TENG), which employs a porous polyurethane (PU) matrix impregnated with a low‐viscosity dielectric lubricant. In response to external mechanical stimuli, the BS‐TENG can “secrete” pre‐stored lubricant to partially fill micro‐gaps between tribo‐layers, thus forming self‐lubrication. This self‐lubricating mechanism not only elevates the electrostatic discharge threshold between tribo‐layers to maximize charge accumulation, thereby facilitating efficient energy release through electrostatic discharge for enhanced power output, but also significantly reduces material abrasion and realizes superior output durability. Benefiting from this effect, the BS‐TENG delivers an average power density of up to 4.6 W m−2, with extraordinary stability to retain 99% of its initial output even after over 60 000 cycles. This work provides a straightforward and effective strategy for realizing high‐performance and long‐stability TENGs, paving the way for their practical applications. [ABSTRACT FROM AUTHOR]

This paper presents a new method for the layered equivalent modeling of slot winding in the stator of a flat wire motor to accurately study the thermal performance under steady-state conditions. The conventional equivalent model for flat wire winding involves treating the slot winding as a single copper rod for temperature analysis. This method is not applicable to flat wire motors under high-power density operating conditions. As the power density of the motor increases, the flat wire winding is more affected by skin effect and proximity effect, resulting in a sharp increase in AC loss and uneven distribution of losses in the slot winding. The conductor losses are highest near the slot opening, a characteristic that conventional model is unable to reflect. The proposed layered modeling method fully takes into account the characteristics of flat wire winding. This method involves adding interlayer insulation to divide the overall modeled conductor into layers and fully considers the thermal parameters, heat transfer characteristics, and distribution of materials within the slot to establish a new equivalent model for flat wire winding. Finally, the comparison of the results with the actual model and experimental tests demonstrates that this method effectively improves the calculation accuracy by 2.2% of the flat wire winding equivalent model. [ABSTRACT FROM AUTHOR]

Flexible electrode is an important part of wearable electronics. Herein, flexible Prussian blue@Carbon nanofibers electrode is fabricated using electrospun carbon nanofiber as electron-donating agents and carbon skeletons. Cubic-shaped Prussian blue with an edge length of 140 nm is in situ deposited on the surface of carbon nanofibers by slow co-precipitation process. The unique design not only obtains the core–shell structure, which is efficient to shorten the diffusion path of sodium ions and improve the electronic conductivity, but also effectively improves the crystallinity of Prussian blue, which is conducive to the improvement of specific capacity and cyclic life. The flexible electrode exhibits superior sodium storage properties including excellent cycling stability (89 mAh g−1 after 2000 cycles at 10C with a considerable capacity retention of 92%) and exceptional rate capability (a capacity up to 90.2 mAh g −1 even at an ultrahigh current density of 50 C). In addition, the self-supporting structure effectively improves the overall energy density of the battery. The strategy using the electron-donating properties of carbon nanofibers open new perspectives to construct other flexible electrodes. [ABSTRACT FROM AUTHOR]

Abstract Simultaneously achieving high‐energy‐density and high‐power‐density is a crucial yet challenging objective in the pursuit of commercialized power batteries. In this study, atomic layer deposition (ALD) is employed combined with a coordinated thermal treatment strategy to construct a densely packed, electron‐ion dual conductor (EIC) protective coating on the surface of commercial LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode material, further enhanced by gradient Al doping (Al@EIC‐NCM523). The ultra‐thin EIC effectively suppresses side reactions, thereby enhancing the stability of the cathode‐electrolyte interphase (CEI) at high‐voltages. The EIC's dual conduction capability provides a potent driving force for Li+ transport at the interface, promoting the formation of rapid ion deintercalation pathways within the Al@EIC‐NCM523 bulk phase. Moreover, the strategic gradient doping of Al serves to anchor the atomic spacing of Ni and O within the structure of Al@EIC‐NCM523, curbing irreversible phase transitions at high‐voltages and preserving the integrity of its layered structure. Remarkably, Al@EIC‐NCM523 displays an unprecedented rate capability (114.7 mAh g−1 at 20 C), and a sustained cycling performance (capacity retention of 74.72% after 800 cycles at 10 C) at 4.6 V. These findings demonstrate that the proposed EIC and doping strategy holds a significant promise for developing high‐energy‐density and high‐power‐density lithium‐ion batteries (LIBs).

Dielectric capacitors with rapid discharge rates and high power density are the basis for advanced pulsed power systems. Sr 0.7 Bi 0.2 TiO 3 (SBT) is expected to be used in energy storage capacitors owing to the small hysteresis and high energy storage efficiency (η). Nevertheless, the low breakdown strength (BDS) limits the enhancement of energy storage density. This study explores the potential of Ho 2 O 3 -modified SBT to address this limitation. Introducing Ho reduces oxygen vacancies, decreases electrical conductivity, and increases thermal conductivity, thus enhancing BDS. The enhancement mechanism of electrical performance is studied through microscopic morphology analysis, structural refinement and numerical simulation. The Sr 0.7 Bi 0.15 Ho 0.05 TiO 3 exhibits remarkable properties, including ultra-low loss tanδ (0.1 %), ultra-high η (95.8 %), and outstanding thermal, frequency, and cycling stability in energy storage properties. Additionally, Sr 0.7 Bi 0.15 Ho 0.05 TiO 3 possesses a high power density (67.9 MW/cm3) and a rapid discharge rate (0.03 μs). The findings indicate that Sr 0.7 Bi 0.15 Ho 0.05 TiO 3 is a prospective material for energy storage capacitors. [ABSTRACT FROM AUTHOR]

The LLC resonant converter used in high-power situations suffers from the problems of high conduction loss and current stress, which can be solved using input-parallel output-parallel (IPOP)-connected converter modules. However, this leads to a multiple increase in the number of magnetic components, which reduces power density. Magnetic integration technology is an effective way to reduce the volume of converters. Currently, the magnetic integrated transformer based on EE-type cores is widely used to realize miniaturization, and it uses leakage inductance instead of resonant inductance to improve power density. However, leakage inductance is difficult to control, and the external radiated magnetic field will produce serious eddy current loss and electromagnetic interference. This article proposes a novel double B-type magnetic integrated transformer, which can integrate the magnetic components of two LLC resonant converters simultaneously and where the resonant inductances are wound independently. The structure contains four low reluctance branches, which are used as the cores of the transformer and the resonant inductance. The decoupling integration method, which integrates the four components into a single core, has been used to increase core utilization and improve power density. On this basis, the transformer's high- and low-voltage windings are cross-arranged to reduce the magnetic field intensity in space, further decreasing the loss and electromagnetic interference. Compared with the EE-type magnetic integrated transformer, the volume of the proposed structure is reduced by 5.9%. A 400W experimental prototype is built, and the results verify the validity of the design. [ABSTRACT FROM AUTHOR]

The LLC resonant converter used in high-power situations suffers from the problems of high conduction loss and current stress, which can be solved using input-parallel output-parallel (IPOP)-connected converter modules. However, this leads to a multiple increase in the number of magnetic components, which reduces power density. Magnetic integration technology is an effective way to reduce the volume of converters. Currently, the magnetic integrated transformer based on EE-type cores is widely used to realize miniaturization, and it uses leakage inductance instead of resonant inductance to improve power density. However, leakage inductance is difficult to control, and the external radiated magnetic field will produce serious eddy current loss and electromagnetic interference. This article proposes a novel double B-type magnetic integrated transformer, which can integrate the magnetic components of two LLC resonant converters simultaneously and where the resonant inductances are wound independently. The structure contains four low reluctance branches, which are used as the cores of the transformer and the resonant inductance. The decoupling integration method, which integrates the four components into a single core, has been used to increase core utilization and improve power density. On this basis, the transformer's high- and low-voltage windings are cross-arranged to reduce the magnetic field intensity in space, further decreasing the loss and electromagnetic interference. Compared with the EE-type magnetic integrated transformer, the volume of the proposed structure is reduced by 5.9%. A 400W experimental prototype is built, and the results verify the validity of the design. [ABSTRACT FROM AUTHOR]

Magnetorheological dampers (MRDs) are applied to hydraulic systems, which not only improve the underdamped characteristics of valve-controlled cylinder systems, but also help hydraulic actuators to resist high load impact. However, the high power density leads to the complexity of the internal flow channel of the damper, which seriously affects the output accuracy of the damping force. It can lead to the fact that existing dynamics models cannot accurately describe the hysteresis characteristics of the MRD. Therefore, this study proposes a simple and general dynamic model of MRD, which solves the problem that existing models are complex and difficult to invert. Firstly, the hydraulic damping actuator with the series MRD is taken as the research object. Based on the stress–strain hysteresis characteristics under the cyclic constitutive model, the hyperbolic tangent curve is reorganized and normalized. It can accurately describe the yield formation and yield dissipation stages of the hysteresis loop. Secondly, the relationship between the parameters of the dynamic model and the current is obtained according to the mechanical experimental data. Then the inverse model of the MRD is established by using the method of section-backstepping. Finally, in the static experiment, the mean absolute percentage error (MAPE) of the force at different velocity is less than 7.5%; in the dynamic experimental test, the MAPE of the force is 9.7%. The inverse dynamics model is verified to have high tracking performance under both static and dynamic forces. And it also indirectly confirms the effectiveness of the forward model. [ABSTRACT FROM AUTHOR]

Abstract Rechargeable Zn–air batteries (ZABs) are considered highly competitive technologies for meeting the energy demands of the next generation, whether for energy storage or portable power. However, their practical application is hindered by critical challenges such as low voltage, CO2 poisoning at the cathode, low power density, and poor charging efficiency Herein, a rechargeable hybrid alkali/acid Zn–air battery (h‐RZAB) that effectively separates the discharge process in an acidic environment from the charging process in an alkaline environment, utilizing oxygen reduction reaction (ORR) and glycerol oxidation reaction (GOR) respectively is reported. Compared to previously reported ZABs, this proof‐of‐concept device demonstrates impressive performance, exhibiting a high power density of 562.7 mW cm−2 and a high operating voltage during discharging. Moreover, the battery requires a significantly reduced charging voltage due to the concurrent utilization of biomass‐derived glycerol, resulting in practical and cost‐effective advantages. The decoupled system offers great flexibility for intermittently generated renewable power sources and presents cost advantages over traditional ZABs. As a result, this technology holds significant promise in opening avenues for the future development of renewable energy‐compatible electrochemical devices.

The recent focus on greenhouse gas emissions from fossil fuel usage has led to strengthened regulations on carbon emissions. Consequently, research on electric vehicles (EV), which have higher energy efficiency compared to internal combustion engine vehicles, is actively being pursued. With advancements in the technology of electronic components in electric vehicles, there is a growing trend in the demand for higher-rated capacities of Low DC-DC Converter (LDC) that possess a wide input-output voltage range. Furthermore, the restricted space within vehicles and the emphasis on high energy utilization necessitate converters with high power density and efficiency. Currently, in electric vehicles, the Active Clamp Forward Converter (ACFC) and the Phase Shift Full-Bridge Converter (PSFB) are commonly applied, as they readily achieve a wide input-output voltage range and high power density. However, ACFC and PSFB encounter difficulties in achieving high efficiency and power density due to the requirement for output inductors with high current specifications. To address these challenges, this study proposes a Two-Transformer Phase Shift Full-Bridge Converter (2-TR PSFB) based on planar transformers, which can replace conventional ACFC and PSFB. The proposed converter achieves high efficiency and power density without the need for high-current output inductors. Additionally, the utilization of GaN power semiconductors allows for a high switching frequency, enabling a significant reduction in the volume of magnetic components. This research presents the operational principles of the 2-TR PSFB and provides design directions. To validate the design, a 2.5 kW prototype was manufactured and tested.

High-frequency isolated LLC converters, which require both high efficiency and high density, are gaining important as pivotal technological challenges. In these converters, the transformer plays an essential role not only in providing galvanic isolation between the input and output and in facilitating voltage step-up and step-down but also as a key component in resonance. An appropriate design of the transformer size and structure is required to achieve both high efficiency and high density. This study introduces a self-equivalent magnetic model that incorporates the fringing effect, presenting a design methodology that utilizes this model. Compared with traditional transformer design methods, the proposed methodology allows for a more precise design by considering both the relative permeability and the magnetic path length (MPL), which represents the average path of the magnetic flux. In addition, we employ pareto optimal design techniques to extract a pareto set of transformer designs that satisfy specific conditions and, apply weighting factors to propose an optimal design. The feasibility of the proposed optimal transformer design methodology was verified through finite element analysis simulations and empirical tests using LLC converters.

A study of a dual rotor radial flux, fractional slot concentrated wound permanent magnet synchronous machine is presented in this paper. The proposed structure is analyzed in two different magnetic polarity configurations of the opposing rotors poles, for performance evaluation. 2D and 3D Finite Element Method simulation results are presented along with experimental validation tests performed on physical prototype under different working conditions, for both considered configurations. The main goal was to achieve a higher power density for the machine. In addition to this, production cost reduction by modularity fabrication techniques, and increasing efficiency through the use of grain-oriented electric steel were considered and studied.

Simple and scalable production of micro-supercapacitors (MSCs) is crucial to address the energy requirements of miniature electronics. Although significant advancements have been achieved in fabricating MSCs through solution-based printing techniques, the realization of high-performance MSCs remains a challenge. In this paper, graphene-based MSCs with a high power density were prepared through screen printing of aqueous conductive inks with appropriate rheological properties. High electrical conductivity (2.04 × 104 S∙m−1) and low equivalent series resistance (46.7 Ω) benefiting from the dense conductive network consisting of the mesoporous structure formed by graphene with carbon black dispersed as linkers, as well as the narrow finger width and interspace (200 µm) originating from the excellent printability, prompted the fully printed MSCs to deliver high capacitance (9.15 mF∙cm−2), energy density (1.30 µWh∙cm−2) and ultrahigh power density (89.9 mW∙cm−2). Notably, the resulting MSCs can effectively operate at scan rates up to 200 V∙s−1, which surpasses conventional supercapacitors by two orders of magnitude. In addition, the MSCs demonstrate excellent cycling stability (91.6% capacity retention and ~100% Coulombic efficiency after 10,000 cycles) and extraordinary mechanical properties (92.2% capacity retention after 5000 bending cycles), indicating their broad application prospects in flexible wearable/portable electronic systems.

Bromine‐based flow batteries (Br‐FBs) are highly competitive for stationary energy storage due to their high energy density and cost‐effectiveness. However, adding bromine complexing agents (BCAs) to electrolytes slows down Br2/Br− reaction kinetics, causing higher polarization and lower power density of Br‐FBs. Herein, in situ vertically aligned MoS2 nanosheet arrays on traditional carbon felt substrates as electrodes to construct high power–density BCA‐free Br‐FBs are proposed. MoS2 arrays exhibit strong adsorption capacity to bromine, which helps the electrodes capture and retain bromine species. Even without BCAs, the battery self‐discharge caused by bromine diffusion is also inhibited. Moreover, the rate‐determining step of Br2/Br− reactions is boosted and the vertically aligned array structure provides sufficient sites, motivating Br2/Br− reaction kinetics and decreasing the battery polarization. The capacity retention rate of the BCA‐free Br‐FB based on MoS2 arrays‐based electrodes reaches 46.34% after the 24‐h standing test at 80 mA cm−2, meeting the requirements of practical applications. Most importantly, this BCA‐free Br‐FB exhibits a high Coulombic efficiency of 97.00% and an ultralong cycle life of 1000 cycles at a high current density of 200 mA cm−2. This work provides an available approach to developing advanced electrode materials for high power–density and long‐lifespan Br‐FBs. [ABSTRACT FROM AUTHOR]

Hydronium‐ion batteries have received significant attention owing to the merits of extraordinary sustainability and excellent rate abilities. However, achieving high‐performance hydronium‐ion batteries remains a challenge due to the inferior properties of anode materials in strong acid electrolyte. Herein, a hydronium‐ion battery is constructed which is based on a diquinoxalino [2,3‐a:2',3'‐c] phenazine (HATN) anode and a MnO2@graphite felt cathode in a hybrid acidic electrolyte. The fast kinetics of hydronium‐ion insertion/extraction into HATN electrode endows the HATN//MnO2@GF battery with enhanced electrochemical performance. This battery exhibits an excellent rate performance (266 mAh g−1 at 0.5 A g−1, 97 mAh g−1 at 50 A g−1), attractive energy density (182.1 Wh kg−1) and power density (31.2 kW kg−1), along with long‐term cycle stability. These results shed light on the development of advanced hydronium‐ion batteries. [ABSTRACT FROM AUTHOR]

Driving motor for all-electric aircraft (AEA) needs high power density and high torque density, resulting in the magnetic load and electrical load of driving motor in a limit state. Therefore, it is important to analyze the accurate calculation of core loss and the technology of loss suppression. Firstly, B35A230 self-bonded electrical steel sheet is used as core, which can reduce core loss caused by machining process. Then the ratio-loss curves of B35A230 at different frequencies and different flux densities are measured by Epstein frame and ring sample method, and the increment of core loss after machining is obtained, and the influence of axial welding paths on stator core loss is analyzed. According to experimental results, Based on the classical stator core loss model, machining factors are considered to improve the accuracy of stator core loss, and a core loss model is adopted to improve accuracy, considering processing factor, alternating and rotating magnetization modes and harmonic magnetic field. Finally, an outer rotor SPMSM for AEA is designed and manufactured, and the no-load loss is tested experimentally, which verified that the self-bonded electrical steel sheet has certain advantages in high power density driving motor.

Bipolar DC–DC converter plays an important role in data center and distributed renewable energy unit with the advantages of high efficiency and low cost. In order to improve the power density of bipolar DC–DC converter, a high frequency and high power density bipolar DC–DC converter based on Gallium Nitride High Electron Mobility Transistor (GaN HEMT) is proposed under the development trend of miniaturization, lightweight and high power density of power electronic converter. By using gallium nitride (GaN) switch device, the switching frequency of the converter is increased to 1 MHz, which effectively reduces the volume and weight of the device. In addition, through the design of high frequency driver circuit, two separate pull-up/pull-down outputs are provided for the control signal, and the rising and falling rates of the switch signal are controlled by adjusting the resistance to obtain good performance and driving stability. The experimental results show that the total weight of the converter with radiator is only 121.6 g, the power density is 35.23 W/in3, and the maximum efficiency can reach 92.7%. Compared with the same type of converter, the volume and weight of the converter are greatly reduced, effectively realizing the goals of miniaturization, lightweight and high power density of the converter.

This study presents a thermoset moulding compound designed for electrical machines with high power densities. The compound reduces residual stresses induced by the difference in thermal expansion during use and by shrinkage in the compound during the manufacturing process. To reduce the internal stresses in the compound, in the electrical sheet lamination and at their interface, first the moulding’s coefficient of thermal expansion (CTE) must match that of the lamination because the CTE of the electrical sheets cannot be altered. Second, the shrinkage of the compound needs to be minimized because the moulding compound is injected around a prefabricated electrical sheet lamination. This provides greater freedom in the design of an electric motor or generator, especially if the thermoset needs to be directly bonded to the electrical sheet. The basic suitability of the material for the injection moulding process was iteratively optimised and confirmed by spiral flow tests. Due to the reduction of the residual stresses, the compound enables efficient cooling solutions for electrical machines with high power densities. This innovative compound can have a significant impact on electric propulsion systems across industries that use laminated electrical sheets.

This article presents a planar transformer design and optimization method for high power density on-board chargers (OBCs) utilized in electric vehicles (EVs). Owing to considerations of electrical safety, OBCs require an isolated converter, leading to a substantial increase in volume due to the inclusion of a transformer. To address this issue and achieve high power density, a planar transformer is used, and an optimized design method is proposed for pattern arrangement, width, and core shape. The feasibility of the design is verified through the development of a 3.3 kW OBC prototype. Consequently, when compared to conventional transformers, the design method in this article results in a 27% reduction in the transformer's height and a 20% reduction in its overall volume. This reduction is advantageous for meeting the requirements of high power density OBCs. [ABSTRACT FROM AUTHOR]

Abstract Sodium‐ion battery (SIB) is considered as a revolutionary technology toward large‐scale energy storage applications. Developing cost‐effective cathode material as well as economical synthesis procedure is a key challenge for its commercialization. Herein, we develop a facile and economic strategy to simultaneously remove rust from the surface of carbon steel and achieve porous and hollow spherical Na4Fe3(PO4)2P2O7/C (HS‐NFPP/C). Benefiting from the desirable structure that fastens the electronic/ionic transportation and effectively accommodates the volume expansion/contraction during discharge/charge process, the as‐prepared cathode exhibits outstanding rate capability and ultralong cycle life. An extraordinarily high‐power density of 32.3 kW kg−1 with an ultrahigh capacity retention of 89.7% after 10 000 cycles are achieved. More significantly, the 3 Ah HC||HS‐NFPP/C full battery manifests impressive cycling stability. Therefore, this work provides an economical and sustainable approach for the massive production of high‐performance Na4Fe3(PO4)2P2O7 cathode, which can be potentially commercialized toward SIB applications.

With the increasing demand for smaller, lighter, and more affordable electromagnetic devices, there is a growing trend toward developing high-power-density transformers and electrical machines. While increasing the operating frequency is a straightforward approach to achieving high power density, it can lead to significant power loss within a limited volume, resulting in excessive temperature rise and device degradation. Therefore, it is crucial to design high-power-density electromagnetic devices that exhibit low power loss and efficient thermal dissipation to address these challenges. Advanced techniques, such as the utilization of novel and advanced electromagnetic materials, hold great promise for overcoming these issues. Specifically, nanocrystalline and amorphous magnetic materials have emerged as highly effective solutions for reducing power loss and increasing efficiency in electromagnetic devices. This paper aims to provide an overview of the application of nanocrystalline and amorphous magnetic materials in transformers and electrical machines, along with key technologies and the major challenges involved. [ABSTRACT FROM AUTHOR]

The Li‐ion capacitors (LICs) develop rapidly due to their double‐high features of high‐energy density and high‐power density. However, the relative low capacity of cathode and sluggish kinetics of anode seriously impede the development of LICs. Herein, the precisely pore‐engineered and heteroatom‐tailored defective hierarchical porous carbons (DHPCs) as large‐capacity cathode and high‐rate anode to construct high‐performance dual‐carbon LICs have been developed. The DHPCs are prepared based on triple‐activation mechanisms by direct pyrolysis of sustainable lignin with urea to generate the interconnected hierarchical porous structure and plentiful heteroatom‐induced defects. Benefiting from these advanced merits, DHPCs show the well‐matched high capacity and fast kinetics of both cathode and anode, exhibiting large capacities, superior rate capability and long‐term lifespan. Both experimental and computational results demonstrate the strong synergistic effect of pore and dopants for Li storage. Consequently, the assembled dual‐carbon LIC exhibits high voltage of 4.5 V, high‐energy density of 208 Wh kg−1, ultrahigh power density of 53.4 kW kg−1 and almost zero‐decrement cycling lifetime. Impressively, the full device with high mass loading of 9.4 mg cm−2 on cathode still outputs high‐energy density of 187 Wh kg−1, demonstrative of their potential as electrode materials for high‐performance electrochemical devices. [ABSTRACT FROM AUTHOR]

Conversion of heat into electrical energy using a thermoelectric generator (TEG) will be beneficial for self‐powered wearable electronic systems. However, the output power of previously reported flexible TE generator (f‐TEG) is too low to meet the requirements of wearable electronic devices. Herein, we report an f‐TEG integrated with inorganic TE materials and exhibiting high output power. The proposed TE device has 60 pairs of p‐type Bi0.5Sb1.5Te3 and n‐type Bi2Te2.7Se0.3 TE legs, and has an extremely low internal resistance (1.09 Ω). This f‐TEG possesses good flexibility (with a bending radius of ∼1 cm) and high output‐power density (up to 4.49 mW/cm2 with a temperature difference of 30 K). To convenience use, a step‐up boost voltage converter is integrated with the TEG to convert the low voltage into a high voltage for micro‐device to work, it provides a new candidate scheme for self‐powered wearable electronic devices. Experiments showed that a LED can be lit up by the f‐TEG with a boost circuit. There results demonstrate that the proposed f‐TEG provides ultrahigh output power density and integrated self‐powered devices, can be used to powering low‐power electronics and sensors through heat harvesting. [ABSTRACT FROM AUTHOR]

Ion conductive membranes with rapid and selective ion transport are in high demand for high‐power energy storage devices. Surface periodic Turing microstructures are scientifically compelling for their high specific surface area which can promote ion transport of membranes. Here, high‐conductivity thin Turing membranes prepared by Co2+ coordination with polybenzimidazole (OPBI) are designed and their efficient ion transport in the alkaline zinc‐iron flow battery (AZIFB) is demonstrated. In this design, the Turing structure increases the effective contact area with the electrolyte, and the 7.9 µm thickness shortens the transmembrane pathway for ions. Molecular dynamics simulations further show that Co2+‐coordination enlarges the inner‐chain volume of membranes and forms continuous water channels for rapid ion transport. The boosting effect of membranes with high ion conductivity is proven by the peak power density and energy efficiency of the AZIFB, which shows an ultrahigh peak power density of 1147 mW cm−2 and demonstrates an energy efficiency of 80% even at a high current density of 200 mA cm−2. [ABSTRACT FROM AUTHOR]

To withstand higher power density (PD), exhibit higher luminous efficiency (LE), use in smaller size and lower cost has become the direction of solid-state lighting technology. In the face of high-density laser irradiation and strong thermal shock, improving the performance of color conversion materials related to laser illumination has become a research hotspot. In this study, The Y 3 Al 5 O 12 :Ce3+ phosphor-in-glass film (Ce:YAG-PiF) was obtained by scraping method. The optimized Ce: YAG-PiF external quantum efficiency (EQE) reaches 74.7%, closing to the phosphor (EQE = 78.47%). Excitingly, at 573 K, the thermal conductivity of sample remains at 9.47 W m−1 K−1. Besides, the sample has an ultra-high LE of 256 lm/W @ 32.47 W/mm2. After recombining with the red phosphor CaAlSiN 3 :Eu2+ (CASN), the color rendering index (CRI) is 84.6, the correlation color temperature (CCT) is 5594 K, and the LE is 192.91 lm/W @ 39.87 W/mm2. More importantly, the relative intensity of laser module packaged by Ce:YAG & CASN-PiF decreased by 15% when tested at 4 W for 24 h. Besides, the packaged laser flashlight has good collimation within a visible illuminance. All the results show that the prepared sample can maintain high emission intensity at high laser PD and have a good heat resistance, which is a promising color conversion material in the field of solid-state laser illumination. [ABSTRACT FROM AUTHOR]

The conventional Static Var Generator (SVG) usually uses IGBT as the power device whose switching loss is high, and switching frequency is low, so the size of output filter and heat sink are large, which limits the improvement of its power density and efficiency. The switching frequency of SiC-MOSFET can be more than twice that of IGBT, and it can withstand higher junction temperature, so that the efficiency and power density of SVG devices can be further improved. This paper optimized the design of SVG from the perspectives of inverter topology, switching frequency, power device loss, device cost, filter, heat sink, etc., and proposed a 220V/50kVar SVG based on SiC-MOSFET discrete devices. It is two-level interleaved as the power topology, a single inductance filter as the filter, and its equivalent switching frequency could reach 100 kHz. The volume of the prototype built is 37L, 66% of the conventional IGBT-SVG product, and the power density is 1.35kVar/L, which is 1.62 times that of the conventional IGBT-SVG product. The peak efficiency of the prototype is as high as 99.03%, and the efficiency is up to 98.75% at full load.

High-frequency and high-power density converters are essential for many applications such as automotive and more electric aircraft. To improve power density, planar magnetic components are increasingly used in power electronic converters owing to their advantages, such as less high-frequency losses, repeatability, and better thermal performance compared to conventional wound components. Considerable attention has been paid to their electrical performance. However, the thermal aspects are essential for enhancing completely their performance. Currently, there is an increasing interest in these critical aspects of high-density power converters. This paper presents a literature review of studies on the thermal modeling of planar magnetics. The papers were organized according to the model type and analyzed to highlight their merits and limitations. A multicriteria comparison of the studied papers was performed. Moreover, the key points and issues related to the thermal modeling are addressed to guide designers in enhancing the thermal aspects of planar magnetic components.