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At the turn of the millennium, developments on metasurfaces lead to a significant step forward in the design of radar absorbing structures, especially at lower frequencies, thanks to a reduced thickness. Still, as with other passive impedance matching systems, they remain constrained in their bandwidth-to-thickness ratio. Fortunately, the recent integration of active electronic components onto metasurfaces has multiplied their functionalities, unlocking new ways to overcome these limitations. For instance, using varactor diodes, which act as variable capacitors, an absorbing metasurface can be rendered tunable to cover a frequency range wider than would any passive system of similar thickness. This is a valuable feature when facing modern frequency-hopping radars. However, the bias-dependent resistance introduced by the varactor diodes can compromise the impedance matching throughout the tunable frequency range. This work, therefore, focuses on the design and measurement of a tunable radar absorbing metasurface using varactor diodes, highlighting the necessity for a joint tuning of capacitance and resistance to grant near-perfect absorption over a wide frequency range. [ABSTRACT FROM AUTHOR]

The study of interface states and bulk traps and their connection to device instability is highly demanded to achieve reliable β-Ga2O3 metal-oxide-semiconductor (MOS) devices. However, a comprehensive analysis of the capture/emission behavior of interface states and bulk traps can be challenging due to widespread time constant distribution. In this study, using capacitance transient measurement tools, trap states of the ZrO2/β-Ga2O3 MOS gate stack were explicitly investigated, particularly its bias- and temperature-dependent relaxation kinetics. As forward bias is enlarged, it is observed that the interface state density (Dit) increases by 12.6%. Two bulk traps with discrete levels identified as 0.43 eV (E1) and 0.74 eV (E2) below the conduction band minimum were extracted by deep-level transient spectroscopy. It is further revealed that the emission processes of E1 and E2 are thermally enhanced, while the capture processes remain insensitive to temperature. The electric-field dependence of E1 indicates that the dominant mechanism follows the rule of Poole–Frenkel emission. The capacitance–voltage (C–V) hysteresis deteriorated at a higher forward bias due to the higher trap density and increased population of trapped charges. These findings provide an important framework for future device optimization to improve the reliability and performance of β-Ga2O3 MOS 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]

Active thermography using pulsed heating is a fast and reliable method for detecting flaws in composite and metallic materials. This paper analyzes the temperature decay that occurs immediately after flash heating the front surface of stainless steel specimens as a function of time, based on a novel application of the equivalent circuit approach (ECA). The temperature decay from the front surface is equated to the discharge of a capacitor. The ECA is based on the charging (temperature rise due to flash heating) of a capacitor, followed by its discharge (temperature decay) through a series of resistors (which depends on the conductivity of the material) and capacitance (which depends on the thermal capacitance of the layers) through which the heat is dissipated. The proposed approach analyzes the sequences of temperature data obtained at each pixel location during cooling from a step wedge and a specimen with multiple flat-bottom holes. Time constant maps derived from the analysis are used to ascertain the thickness of the step wedge, detect the flaws, and evaluate the remnant thickness of the flaws. A correlation has been established between the thickness and the time constants. The above approach has been used to estimate the diameter of the flat-bottom holes. [ABSTRACT FROM AUTHOR]

Electrochemical Double Layer Capacitors (EDLCs) with ionic liquid electrolytes outperform conventional ones using aqueous and organic electrolytes in energy density and safety. However, understanding the electrochemical behaviors of ionic liquid electrolytes under compressive/tensile strain is essential for the design of flexible EDLCs as well as normal EDLCs, which are subject to external forces during assembly. Despite many experimental studies, the compression/stretching effects on the performance of ionic liquid EDLCs remain inconclusive and controversial. In addition, there is hardly any evidence of prior theoretical work done in this area, which makes the literature on this topic scarce. Herein, for the first time, we developed an atomistic model to study the processes underlying the electrochemical behaviors of ionic liquids in an EDLC under strain. Constant potential non-equilibrium molecular dynamics simulations are conducted for EMIM BF4 placed between two graphene walls as electrodes. Compared to zero strain, low compression of the EDLC resulted in compromised performance as the electrode charge density dropped by 29%, and the performance reduction deteriorated significantly with a further increase in compression. In contrast, stretching is found to enhance the performance by increasing the charge storage in the electrodes by 7%. The performance changes with compression and stretching are due to changes in the double-layer structure. In addition, an increase in the value of the applied potential during the application of strain leads to capacity retention with compression revealed by the newly performed simulations. [ABSTRACT FROM AUTHOR]

In recent years, neural networks have achieved phenomenal success across a wide range of applications. They have also proven useful for solving differential equations. The focus of this work is on the Poisson–Boltzmann equation (PBE) that governs the electrostatics of a metal–oxide–semiconductor capacitor. We were motivated by the question of whether a neural network can effectively learn the solution of PBE using the methodology pioneered by Lagaris et al. [IEEE Trans. Neural Netw. 9 (1998)]. In this method, a neural network is used to generate a set of trial solutions that adhere to the boundary conditions, which are then optimized using the governing equation. However, the challenge with this method is the lack of a generic procedure for creating trial solutions for intricate boundary conditions. We introduce a novel method for generating trial solutions that adhere to the Robin and Dirichlet boundary conditions associated with the PBE. Remarkably, by optimizing the network parameters, we can learn an optimal trial solution that accurately captures essential physical insights, such as the depletion width, the threshold voltage, and the inversion charge. Furthermore, we show that our functional solution can extend beyond the sampling domain. [ABSTRACT FROM AUTHOR]

Electrode–electrolyte interfacial properties characterize the functioning of electrochemical devices, and reactive molecular dynamics simulations, using reactive force fields (ReaxFF) and charge equilibration (QEq) techniques, are classical atomistic methods for investigating the processes that govern the device properties. However, the numerical implementation of ReaxFF and QEq treats Coulomb interaction with a short-distance cutoff for computational speed, thereby limiting interactions among atoms to a domain containing only their neighbor lists. Excluding long-distance Coulomb interactions makes the description of electrostatics in large-scale systems intractable. We apply Ewald sum in the extension of ReaxFF to include long-range Coulomb (LRC) interactions and investigate the effect of the inclusion on the electrostatic and capacitive properties of graphene–water interfaces at different applied potentials in comparison with the original ReaxFF. The study shows that with the inclusion of long-range Coulomb, the capacitance amounts to 4.9 ± 0.2 μF cm−2 compared with 4.4 ± 0.2 μF cm−2 predicted by the original ReaxFF [with short-range Coulomb (SRC)]; thus, indicating that SRC underestimates the capacitance of water between graphene walls by 12% when compared with the 5.0 μF cm−2 predicted with the extended simple point charge (SPC/E) water model. Thus, the results indicate that LRC ReaxFF/QEq have the ability and advantage to model electrochemical processes at a more realistic Coulomb interaction description and foster the processing of the details about the operation of electrochemical devices than the SRC. [ABSTRACT FROM AUTHOR]

The relationship between the electrical properties and the carrier trap properties of the SiO2/GaN metal–oxide–semiconductor (MOS) capacitors was investigated using electrical measurements and deep level transient spectroscopy (DLTS). The capacitance–voltage (C–V) measurement showed that the frequency dispersion of the C–V curves became smaller after an 800 °C annealing in O2 ambient. DLTS revealed that before the annealing, the interface trap states, in a broad energy range above the midgap of GaN, were detected with the higher interface state density at around 0.3 and 0.9 eV below the conduction band minimum (EC) of GaN. Moreover, the oxide trap states were formed at around 0.1 eV below the EC of GaN, plausibly indicating a slow electron trap with a tunneling process. Although both trap states affect the electrical reliability and insulating property of the SiO2/GaN MOS capacitors, they were found to drastically decrease after the annealing, leading to the improvement of the electrical properties. [ABSTRACT FROM AUTHOR]

We present a method for simulating any non-interacting and time-periodic tight-binding Hamiltonian in Fourier space using electric circuits made of inductors and capacitors. We first map the time-periodic Hamiltonian to a Floquet Hamiltonian, which converts the time dimension into a Floquet dimension. In electric circuits, this Floquet dimension is simulated as an extraspatial dimension without any time dependency in the electrical elements. The number of replicas needed in the Floquet Hamiltonian depends on the frequency and strength of the drive. We also demonstrate that we can detect the topological edge states (including the anomalous edge states in the dynamical gap) in an electric circuit by measuring the two-point impedance between the nodes. Our method paves a simple and promising way to explore and control Floquet topological phases in electric circuits. [ABSTRACT FROM AUTHOR]

Within the framework of the classical, mean-field Poisson–Boltzmann (PB) theory, we carry out direct numerical simulations to determine the differential capacitance of a closed nanochannel of a circular cross section, embedded in a polymeric host with charged walls and sealed at both ends by metal electrodes under an external potential bias. Our approach employs the modified PB equation, which accounts for the finite size of ions and the dependency of the electrolyte's relative permittivity on the local electric field. In view of the absence of reservoirs, the modified PB equation becomes subject to global algebraic constraints, without prior knowledge of a bulk electrolyte concentration. Equilibrium ion distributions and differential capacitance curves are investigated as functions of electrolyte properties and the surface charge density modulation. This modulation leads to asymmetric differential capacitance curves that can be tuned. More generally, our approach provides a transparent numerical framework for accurately simulating confined nanofluidic systems with new physical properties that may be exploited in novel iontronic circuit elements. [ABSTRACT FROM AUTHOR]

Tetragonal ZrO2 high-k material as the dielectric layer of dynamic random access memory (DRAM) capacitors faces bulk defect related leakage current, which is one of the main obstacles to the down-scaling of DRAM devices. Boron and hydrogen impurities are known to be responsible for leakage current degradation and are hard to be removed in DRAM capacitors. However, the defect origins of boron and hydrogen leakage current are still puzzling, and corresponding suppression methods are urged. In this work, the properties of boron and hydrogen impurities in tetragonal ZrO2 are investigated using first-principles calculations, and defect types such as boron and hydrogen interstitials are discovered to have detrimental defect levels related to leakage current. Based on the discovery, a chlorine co-doping approach that can passivate detrimental defects by forming defect complexes is further proposed. By introducing level repulsion due to coupling between defect states, defect levels of passivated defect complexes are moved out of the region of leakage current contribution. Thus, bulk defect related leakage current in tetragonal ZrO2 based DRAM capacitors can be effectively suppressed without device structure modification, and a broad vista is opened for next-generation DRAM devices. [ABSTRACT FROM AUTHOR]

The discharge performance of antiferroelectric (AFE) capacitors is complicated and difficult to simulate due to the nonlinear polarization behavior of AFE. In this work, a nonlinear model for pulsed discharge AFEs was proposed based on a combination of the Preisach model and Kirchhoff's law. The model was driven by the data from first-order reversal curves and direct-current-bias (DC-bias) dielectric test measurements. Thus, the discharge behavior of the AFE can be studied without actual discharge experiments. Specifically, AFE discharge waveforms were calculated and evaluated for different size parameters and external circuit parameters that were conducive to compare the properties of different AFE materials. Moreover, the size effect of the capacitor on the discharge performance was discussed, which should draw the attention of researchers to prevent exaggerated conclusions. As a consequence, this method would fill the gap of AFE discharge simulation. [ABSTRACT FROM AUTHOR]

The health management of railway signal equipment in the high-speed railway is a key link between intelligent operation and maintenance. Accurately predicting the health state of compensation capacitors is of great significance to ensure the reliable work of track circuits. This paper proposes an improved deep neural network algorithm focusing on the problem of long-term accurate health forecasts for compensation capacitors. First, establishing a transmission state model for degradation mechanism mining, the difference function that can quantitatively evaluate features is defined by piecewise processing cab signaling receiving voltage. Introducing the degradation model, predictive driving under both model and data is implemented. Then, the convolutional neural networks and bidirectional long–short-term memory are combined and improved to construct a novel artificial intelligence combination strategy, while parameters are optimized based on the sparrow search algorithm. Finally, facing the conditional repair of compensation capacitors, we set a reasonable threshold for the occurrence of hidden dangers to complete fault warning. This novel and practical approach effectively explores the procedure of prognosis and health management, while the refined maintenance will better utilize current monitoring information, helping the intelligence and accuracy of safety control decision-making. [ABSTRACT FROM AUTHOR]

Black phosphorus (BP) has been recognized as an alluring fast‐charging anode for batteries/supercapacitors due to its substantial theoretical capacity, propitious lithiation potential, and large interlayer spacing. Nonetheless, it is encumbered by challenges of low electronic conductivity, momentous volume expansion (≈300%), and pernicious shuttle effect induced by soluble polyphosphides. Here a BP heterostructure covalent bonded by metallic antimony (Sb) is showed, which can promote the reaction dynamics of BP and greatly ameliorate the cycling performance. Robust P─Sb covalent bonds are methodically engineered to regulate the Femi level, endowing enhanced electronic conductivity. The in situ generated Li7SbO6 ionic conductor in the P/Sb interface during the lithiation process ensures the fast Li+ transport. Furthermore, Sb offers strong anchoring and chemical adsorption capability on soluble lithium polyphosphides, preventing the shuttle issue. As a result, a lithium‐ion capacitor (LIC) full‐cell based on Sb@BP/C anode demonstrates a superior energy density of 174.3 W h kg−1 and a power density of 23.7 kW kg−1, as well as exceptional reversible capacity retention. This work provides insights into the regulation of reaction kinetics and chemical adsorption capability of BP, offering guidance for designing high‐capacity and stable BP‐based anodes. [ABSTRACT FROM AUTHOR]

With the widespread use of batteries, their increased performance is of growing in importance. One avenue for this is the enhancement of ion diffusion, particularly for solid‐state electrolytes, for different ions such as lithium (Li+) and magnesium (Mg2+). Unraveling the origin of better cation diffusion in confined ionic liquids (ILs) in a polymer matrix (ionogels) is compared to that of the IL itself. Ionic conductivity measured by electrochemical impedance spectroscopy for ionogels (7.0 mS cm−1 at 30 °C) is very close to the conductivity of the non‐confined IL (8.9 mS cm−1 at 30 °C), that is, 1‐ethyl‐3‐methyimidazolium bis(trifluorosulfonyl)imide (EMIM TFSI). An even better ionic conductivity is observed for confined EMIM TFSI with high concentrations (1 m) of lithium or magnesium salt added. The improved macroscopic transport properties can be explained by the higher self‐diffusion of each ion at the liquid‐to‐solid interface induced by the confinement in a poly‐vinylidenedifluoride (PVDF) polymer matrix. Upon confinement, the strong breaking down of ion aggregates enables a better diffusion, especially for TFSI anion and strongly polarizing cations (e.g., Li+, Mg2+.). The coordination number of these cations in the liquid phase confirmed that Li+ and Mg2+ interact with the polymer matrix. Moreover, it is a major result that the activation energy for diffusion is lowered. [ABSTRACT FROM AUTHOR]

This article explores the measurement of electric fields in parallel plate capacitors. It explains the concept of parallel plate capacitors and their applications in experiments related to electric charges. The article acknowledges that real-life capacitors do not meet ideal conditions and presents standard formulas for ideal capacitors. It also discusses a simple experiment using a charged bead to measure the electric field inside and outside a parallel plate capacitor, along with the theoretical framework and equations involved. The authors conducted experiments to measure the electric field in both regions and discovered the presence of a field outside the capacitor due to the fringing effect. The study provides a theoretical explanation and a practical apparatus for measuring the electric field of a parallel plate capacitor. The article was authored by Taehun Jang, Hyejin Ha, Sang Ho Sohn, and Jungmin Moon, with Sang Ho Sohn being a professor of physics at Kyungpook National University in South Korea. [Extracted from the article]

In the realm of medium/high voltage applications, the modular multilevel converter with an active power filter (APF-MMC) emerges as a technology that eliminated the inherent voltage fluctuations of larger sub-module (SM) capacitors. However, the introduced APF circuit in each phase can only deal with power in even frequencies, and the APF-MMC cannot be directly applied in the field of motor drives with low-frequency operation. In this paper, based on the APF-MMC topology, by adding two high-frequency variables as control degrees of freedom, the base frequency power is transferred to high-frequency power, which can considerably minimize the capacitor voltage ripple in the low-frequency region of the topology. In addition, the influence of the injected high-frequency variables on the output characteristics of the topology is eliminated by controlling the APF circuit as hardware degree of freedom. Its equivalent circuit and operating principle are introduced in detail. Concurrently, a control method is proposed for the APF circuit, ensuring seamless operation of the converter. Finally, through a combination of simulation and experimental results, it is demonstrated that the APF-MMC topology surpasses the conventional MMC in its efficacy under low-frequency operation. [ABSTRACT FROM AUTHOR]

Currently, many inverters employ inductors to boost the AC voltage. However, this leads to increased current distortion and limits the voltage boosting capability of the inverter. To address the above issue, a triple two-level inverter is proposed in this paper. The proposed inverter adopts a switched-capacitor boost circuit to boost the AC output voltage and to generate a multi-level voltage. Simultaneously, a three-phase full-bridge circuit is assigned to convert the DC voltage into AC voltage. In addition, a novel space vector modulation strategy is introduced to achieve capacitor voltage self-balance. Finally, simulation and experimental platforms have been established to verify the effectiveness of proposed inverter. The obtained results show that the proposed inverter meets the requirements for the expected inverter. [ABSTRACT FROM AUTHOR]

Summary: This paper proposes a new extendable multicell topology based on the conventional quasi‐Z‐source converter (QZSC). The proposed topology has a multicell scheme and employs an active switched capacitor/inductor (ASC/SL) network. Therefore, it is entitled extended multicell ASC/SL QZSC (EMc‐ASC/SL‐QZSC). The proposed topology is augmented by cascading a modular cell consisting of two capacitors, an inductor, and a diode. The EMc‐ASC/SL‐QZSC offers significant advantages over existing QZSC‐based configurations. It has a high boosting capability that results in a wider output voltage range while simultaneously reducing voltage stress on capacitors and switching devices, all without losing voltage gain. Furthermore, this topology effectively reduces input current ripple, which contributes to a smoother charging current profile for capacitors, reducing electromagnetic interference (EMI) and improving overall efficiency. The practicality and performance of the EMc‐ASC/SL‐QZSC topology are comprehensively assessed through extensive numerical simulations and experimental verification, utilizing a laboratory‐built prototype. [ABSTRACT FROM AUTHOR]

This paper proposes a unique sensor for detecting total ionizing dose (TID) on metal–oxide–semiconductor (MOS) devices. The proposed capacitive radiation sensor is based on commercial 180 nm complementary metal-oxide semiconductor (CMOS) technology. The sensor parameters of 180 nm length (L) and 20 nm oxide thickness (TOX) have been finalized based on simulation and mathematical analysis. Low and high radiation doses ranging from 100 rad to 1 Mrad are used to characterize it. The sensor's sensitivity for 0–10 krad is 20 mV/krad, 10 krad–100 krad is 3.9 mV/krad, and 100 krad–1 Mrad is 0.6 mV/krad when threshold shift is considered into account. Analysis of fixed oxide charge and interface trap charge generation due to ionizing radiation is done. Because interface traps are crucial to device performance, this device is evaluates using traps between 1 E06 cm−3 and 1 E14 cm−3 for realistic performance. Every interface trap exhibits a threshold voltage (VT) shift. Visual technology computer-aided design (TCAD) simulator was used to build, study, and evaluate a capacitive radiation sensor that might be used as a dosimeter for TID monitoring. [ABSTRACT FROM AUTHOR]

In this study, the aim is to evaluate three-phase (3φ) three-level (3L) neutral point clamped AC/DC rectifier for high-power applications. The rectifier analysis has been simulated using a new modified carrier-based level-shifted PWM technique. The 3L-NPC rectifier, which uses the new level-shifted PWM technique, is compared with the classical triangular carrier-based PWM signal. This new PWM technique provides low output voltage ripple, low total harmonic distortion (THD) for input current, unit input power factor, a well-regulated DC bus voltage and capacitor voltage balance for the NPC rectifier which is considered for implementation in high-power applications. This proposed modified carrier-based PWM is highly successful for 3L-NPC rectifier which is rated from 75 to 350 kW power applications. The system simulation results demonstrate the validity and flexibility of the proposed new carrier-based level-shifted PWM method for NPC rectifier in high-power applications. [ABSTRACT FROM AUTHOR]

A cross-coupled cascode feedback design for a frequency compensated operational transconductance amplifier (OTA) is presented here. This OTA is able to achieve a power supply rejection ratio (PSRR) 93 dB (DC) and common mode rejection ratio (CMRR) 41.41 dB (DC) with very low value of compensation capacitors 0.1pF driving a large load of 400pF||2.2kΩ. The proposed OTA design is simulated in 180 nm technology using Electric VLSI tool for validating its performance. The simulated results, PSRR 93 dB at 1 kHz, 83.42 dB at 1 MHz, 71.23 dB at 1 GHz are noted. Further simulated results, CMRR 41.41 dB at 1 kHz, 41.97 dB at 1 MHz and 70.79 dB at 1 GHz are also observed. Small signal and transient performances are analyzed and post-layout simulations bring out the following results: DC gain of 43.21 dB, unity-gain-frequency (UGF) of 27 MHz, Phase Margin of 48.50, slew-rate (+) of 4.63 V/μs and slew-rate (−) of 1.00 V/μs. Additionally, the circuit occupies an area of 0.014 mm 2 and the power consumption observed is 3.17 mW. [ABSTRACT FROM AUTHOR]

This paper presents layer‐by‐layer additive manufacturing (AM) of molten metal microdroplets and dielectric materials to fabricate multilayer hybrid circuit boards featuring interdigitated 3D capacitors. The printed metal lines have a low resistance of 5 mΩ/mm, 12 times lower than state‐of‐the‐art conductive inks. Exploiting the advantages of Sn‐based oxide as an ideal candidate for Electrical Energy Storage Systems (ESS), we successfully fabricated an out‐of‐plane capacitor module using a combination of polymer and metal materials. The fabrication process exhibited an exceptional aspect ratio of 16, illustrating the successful incorporation of 20 metal layers in the out‐of‐plane capacitor module. Q factor obtained for the 3D capacitor was in the range of 66–500. Additionally, a fully automated printing technique was employed to produce a multilayer hybrid electrical printed circuit board (PCB), eliminating the need for post‐processing. This streamlined approach presents an efficient and comprehensive solution for the one‐stop printing of intricate electrical circuits. © 2024 The Authors. IEEJ Transactions on Electrical and Electronic Engineering published by Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

[Display omitted] Lithium ion capacitors (LICs) are a new generation of energy storage devices that combine the super energy storage capability of lithium ion batteries with the satisfactory power density of supercapacitors. The development of high-performance LICs still faces great challenges due to the unbalanced reaction kinetics at the anode and cathode. Therefore, it is an inevitable need to enhance the electron/ion transfer capability of the anode materials. In this paper, to obtain a superior-rate and high-capacity Ni 3 S 2 -based anode, highly conductive Ti 3 C 2 T x MXene sheets were introduced to sever as the carrier of Ni 3 S 2 nanoparticles and simultaneously an amorphous carbon layer which coats onto the surface of Ni 3 S 2 nanoparticles was in-situ generated by the carbonization of dopamine reactant. The as-synthesized Ni 3 S 2 /Ti 3 C 2 T x /C composite exhibits a high specific surface area (112.6 m2/g) because of the addition of Ti 3 C 2 T x that can reduce the aggregation of Ni 3 S 2 nanoparticles and the in-situ generated amorphous carbon layer that can suppress the growth of Ni 3 S 2 nanoparticles. The Ni 3 S 2 /Ti 3 C 2 T x /C anode possesses a remarkable reversible discharge specific capacity (626.0 mAh/g under 0.2 A/g current density), which increases to 1150.8 mAh/g after 400-cycle charge/discharge measurement at the same measurement condition indicating eminent cyclability, along with superior rate capability. To construct a superior-performance LIC device, a sterculiae lychnophorae derived porous carbon (SLPC) cathode with an average discharge specific capacity of 73.4 mAh/g@0.1A/g was prepared. The Ni 3 S 2 /Ti 3 C 2 T x /C//SLPC LIC device with optimal cathode/anode mass ratio has a satisfactory energy density ranging from 32.8 to 119.1 Wh kg−1 at the corresponding power density of 8799.4 to 157.5 W kg−1, together with a prominent capacity retention (95.5 %@1 A/g after 10,000 cycles). [ABSTRACT FROM AUTHOR]

In this work, we show that a magnon spin capacitor can be realized at a junction between two exchange coupled ferromagnets. In this junction, the buildup of magnon spin over the junction is coupled to the difference in magnon chemical potential, realizing the magnon spin analogue of an electrical capacitor. The relation between magnon spin and magnon chemical potential difference directly follows from considering the magnon density–density interaction between the two ferromagnets. We analyze the junction in detail by considering spin injection and detection from normal metal leads, the tunneling current across the junction, and magnon decay within the ferromagnet, showing that such a structure realizes a magnon spin capacitor in series with a spin resistor. Choosing yttrium iron garnet as the ferromagnet, we numerically calculate the magnon spin capacitance which ranges from picofarad to microfarad, depending on the area of the junction. We therefore conclude that the magnon spin capacitor could directly be of use in applications. [ABSTRACT FROM AUTHOR]

In recent years, liquid–solid triboelectric nanogenerator (LSTENG) has attracted great attention. However, its low average power density and long charging time limit the practical application of this technique. Here, for the first time, a liquid–solid triboelectric nanogenerator combined with external charge‐pumping method (ECP‐LSTENG) is proposed. Compared to traditional LSTENGs, a charge storage capacitor is added in this ECP‐LSTENG to store the output charges from the pumping generator. Then, a charge extraction capacitor is formed by the spreading and shrinking processes of falling droplet, while the charging and discharging process between charge storage and extraction capacitors can generate displacement current output for external circuit. Meanwhile, it is found that a special charged droplets adhesion phenomenon happens at the liquid–solid interface, which seriously hinders the continuous output of ECP‐LSTENG. To overcome this limitation, a special coaxial deceleration commutation component is designed to ensure continuous output of the ECP‐LSTENG. Finally, the peak power density of a droplet (50 µL) reaches 231.8 W m−2, surpassing the highest research record to date by 1.43 times. This ECP‐LSTENG provides a different approach for the future development of large‐scale integrated raindrop generators for efficient raindrop energy harvesting. [ABSTRACT FROM AUTHOR]

A flexible triple-band and polarization-insensitive rectifying metasurface (RMS) is presented in this article. The surface consists of three parts: a periodic metal unit with integrated diodes, a DC filter composed of series inductor and parallel capacitor, and a load resistor. Due to the direct integration of rectifying diodes and interconnected branches within and between the units, complex matching networks can be eliminated and the overall structure is simplified. A 6 × 6 array is fabricated and measured. The results show that at a low input power of 0 dBm, the RMS has efficiency of 51.81%, 44.25%, and 42.01% at 2.9 GHz, 5.2 GHz, and 5.77 GHz, respectively. The efficiency remains consistent under different polarization angles, demonstrating the polarization insensitivity property of RMS. Additionally, the flexible substrate enables high efficiency in the S-band and Wi-Fi bands even under a certain range of bending, revealing its superior flexibility and adaptability. Therefore, it is well suited for ambient energy harvesting and wireless self-powered miniaturized internet of things devices. [ABSTRACT FROM AUTHOR]

[Display omitted] Coupling TiO 2 within N -doped porous carbon (NPC) is essential for enhancing its Na+ storage performance. However, the role of different N configurations in NPC in improving the electrochemical performance of TiO 2 is currently unknown. In this study, melamine is deliberately incorporated as a pore-forming agent in the self-assembly process of metal organic framework precursors (NH 2 -MIL-125(Ti)). This intentional inclusion of melamine leads to the one-pot and in-situ formation of highly active edge-N, which is vital for the development of TiO 2 /NPC with exceptional reactivity. Electrochemical performance characterization and density functional theory (DFT) calculation indicate that the interaction between TiO 2 and pyridinic-N enriched NPC can effectively narrow the bandgap of TiO 2 /NPC, thereby significantly improving electron/ion transfer. Additionally, the abundant mesoporous channels, high N content and oxygen vacancies also contribute to the fast reaction kinetics of TiO 2 /NPC. As a result, the optimized TiO 2 /NPC-M, with high proportion of pyridinic-N (44.1 %) and abundant mesoporous channels (97.8 %), delivers high specific capacity of 282.1 mA h−1 at 0.05 A g−1, superior rate capability of 177.3 mA h−1 at 10 A g−1, and prominent capacity retention of 89.3 % over 5000 cycles even under ultrahigh 10 A g−1. Furthermore, the TiO 2 /NPC-M//AC sodium ion capacitors (SIC) device achieves a high energy density of 136.7 Wh kg−1 at 200 W kg−1. This research not only offers fresh perspectives on the production of high-performance TiO 2 -based anodes, but also paves the way for customizing other active materials for energy storage and beyond. [ABSTRACT FROM AUTHOR]

With the rapidly growing demand for clean energy and energy interconnection, there is an urgent need for rapid and high-capacity energy storage technologies to realize large-scale energy storage, transfer energy, and establish the energy internet. Supercapacitors, which have advantages such as high specific capacitance, fast charging and discharging rates, and long cycle lifetimes, are being widely used in electric vehicles, information technology, aerospace, and other fields. The performance of supercapacitors is crucially dependent on electrode materials. These can be categorized into electric double-layer capacitors and pseudocapacitors, primarily made from carbon and transition metal oxides, respectively. However, effectively monitoring the physicochemical properties of electrode materials during preparation and processing is challenging, which limits the improvement of supercapacitors' performance. Plasma materials preparation technology can effectively affect the materials preparation processing by energetic electrons, ions, free radicals, and multiple effects in plasma, which are easily manipulated by operation parameters. Therefore, plasma material preparation technology is considered a promising method to precisely monitor the physicochemical and electrochemical properties of energy storage materials and has been widely studied. This paper provides an overview of plasma materials preparation mechanisms, and details of the plasma technology application in the preparation of transition metal hybrids, carbon, and composite electrode materials, as well as a comparison with traditional methods. In conclusion, the advantages, challenges, and research directions of plasma materials preparation technology in the field of electrode materials preparation are summarized. [ABSTRACT FROM AUTHOR]

A novel fluorine-free electrolyte comprising a solution of lithium bis(oxalato)borate in ethyl isopropyl sulfone is presented. It is characterized by its safety and non-toxic properties, along with the capability to effectively suppress the anodic dissolution of aluminum. Successful high-temperature application of this electrolyte in combination with various capacitor- and battery-like electrode materials is shown. Further utilization in a lithium-ion capacitor and a lithium-ion battery is demonstrated. To the best of the knowledge, the lithium-ion capacitor presented in this work represents the first entirely fluorine-free device suitable for high-temperature applications. When operating at 60 °C, this device delivers a maximum energy output of 169 Wh kg-1 AM at a power of 200 W kg-1 AM and even 80 Wh kg1 AM at 10 kW kg-1 AM, along with the ability to retain 80% of its initial capacitance after 3500 cycles at 5 A g-1. As such, this novel electrolyte is a promising alternative to conventional fluorine-containing configurations since its performance is capable to match or even surpass that of most similar laboratory-scale LICs. [ABSTRACT FROM AUTHOR]

Metallized film capacitors (MFCs) are widely used in the power electronics industry due to their unique self-healing (SH) capability. SH performance is an essential assessment for MFC reliability verification in industrial production. The SH phenomenon of metallized films usually occurs rapidly in a very short period, and its real-time evolution details are often difficult to capture and analyze. In this paper, a test system for the SH performance of metallized films for capacitors was constructed. The system consists of three components: a voltage–current characteristic testing and current pulse capture device, a microscopic image real-time acquisition device, and an integrated analysis processing device. Through the voltage–current characteristic testing and current pulse capture device, the electrical parameters of the SH point, such as SH times, breakdown field strength, SH current, and SH energy, are obtained; through a microscopic image real-time acquisition device, the real-time spatial positioning of the SH point was obtained, and the interconnection between the morphology of the SH point and the electrical properties was established. The relationship between the SH point and the temperature distribution was further established using thermal imaging technology, which lays the foundation for a thorough and timely assessment and analysis of the failure mechanism and the real-time evolution of the metallized film SH process. This significantly improves the effectiveness of SH property research. [ABSTRACT FROM AUTHOR]

Multiple pulse charging modules were designed and tested for synchronous use in scaled experiments. The pulse chargers are each capable of charging a nanofarad-sized capacitive load to 100 kV in less than 10 µs. This is achieved by initially charging a microfarad-sized capacitor to a maximum of 3 kV, then, using a thyristor switch, discharging the capacitor into two transformers paralleled on the primary side. Each transformer steps the voltage up to 50 kV, with the transformer having opposing polarities and a common neutral on the secondary. Thus, the full 100 kV is obtained by placing the nanofarad-sized capacitor between the +50 and −50 kV terminals. The pulse chargers use a microcontroller to monitor and control the pulse charger in addition to communicating with the user as well as other pulse chargers. For increased battery life, each pulse charger is kept in a low-power state while not in use. Upon startup, the pulse chargers automatically detect the number of modules in the system, the position of itself in the system, and the timing delays associated with each pulse charger in the system. This information is essential for synchronous charging and provides individual information and controls for the pulse chargers. [ABSTRACT FROM AUTHOR]

Nickel oxide nanoparticles (NiO NPs) are synthesized using olive leaf extract (OLE), which contains a range of polyphenols. These polyphenols serve as both reducing and capping agents, stabilizing the nanoparticles. Aqueous nickel acetate is employed as a precursor. Simultaneously, exfoliated graphene (EG) is obtained via electrochemical exfoliation of graphite in aqueous solutions. These materials were employed as electroactive components in supercapacitor applications. Characterization of NiO and EG involved thermogravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and scanning/transmission electron microscopy (SEM/TEM), alongside Brunauer−Emmett−Teller (BET) analysis, confirming the formation of crystalline NiO NPs with a cubic phase and Fm-3m space group. Micrographs revealed nanoscale dimensions for both NiO and EG with a substantial surface area, as verified by BET analysis. Symmetric (NiO/NiO, EG/EG) and asymmetric (NiO/EG) supercapacitors were fabricated using the doctor blade method. Electrode evaluation, employing field-emission scanning electron microscopy FESEM, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), demonstrated promising morphological and electrochemical characteristics. At low scan rates, both symmetric and asymmetric supercapacitors exhibited a notable gravimetric capacitance (221, 111, and 162 F g–1 at 1 mV s–1). Additionally, they revealed higher power density (173, 137, and 161 W kg–1 at 10 mV s–1), showcasing pseudocapacitive and electric double-layer capacitor (EDLC) behavior for NiO NPs and EG, respectively. This research significantly contributes valuable insights by presenting a sustainable synthesis route for NiO NPs, developing high-performance supercapacitor electrodes, and achieving a comprehensive understanding of the electrochemical behavior of NiO NPs and EG. [ABSTRACT FROM AUTHOR]

This study introduces an innovative filter topology capable of providing simultaneous positive and negative gain outputs for one-fractional order LP, with high-pass, all-pass, and fractional-order shelving filter responses. The circuit, utilizing multi-output second-generation current-controlled conveyors, stands out as the first to deliver ten outputs, incorporating both integer and fractional-order filter responses, without requiring additional components. Its current-mode design simplifies the process, employing minimal active and grounded passive elements, making it appropriate for low-voltage/low-power applications. The filter utilizes fifth-order Oustaloup approximation and Foster type-I RC networks for fractional-order capacitors, providing enhanced control over the transition slope. PSpice simulations confirmed a 1 kHz cut-off, showcasing low power consumption, minimal noise, and a wide dynamic range, positioning the filter as suitable for sensors, control, and acoustic applications. [ABSTRACT FROM AUTHOR]

A high‐efficiency frequency tripler operating up to 330 GHz is developed based on a novel quad‐port balanced configuration. The proposed circuit could inhibit the even‐order harmonics with great idler loops, leaving out the lossy capacitors required in conventional triplers. Meanwhile, this topology employs two pairs of discrete Schottky diodes, which could increase the power‐handling capability by a factor of 2. In this way, a 330 GHz balanced tripler is implemented with four discrete Schottky diodes mounted on a 30‐μm‐thick quartz substrate. At room temperature, the implemented tripler module features a peak output power of 41.1 mW (@321.4 GHz) and a peak efficiency of 12.4%. [ABSTRACT FROM AUTHOR]

In this paper, a novel switched capacitor converter has been proposed to generate 7-levels using seven semiconductor switches (7S7L) to get triple gain in the output voltage which is supplied by a single dc source. A PWM technique, phase disposition pulse width modulation (PD-PWM) has been designed to achieve a suitable switching operation for the 7S7L inverter. In addition, the capacitor voltage is balanced and the suggested inverter uses a charging inductor to decrease the capacitor inrush current, which is a shortcoming in the switched-capacitor multilevel inverters. Moreover, the 7S7L inverter is used to interface the solar panels with the utility grid using a synchronous reference frame-based controller. To check the efficiency, taking actual data, power loss calculation has been discussed for the 7S7L inverter. To illustrate the better performance of the proposed 7S7L inverter than the existing seven-level SC-MLI presented in the literature, a comparative study is also undertaken. To verify the feasibility and effectiveness of the proposed topology, a converter is simulated using Matlab/Simulink. To validate the simulation results, a real-time study is completed using the OPAL-RT 4510 real-time platform. [ABSTRACT FROM AUTHOR]

The modular multilevel converter (MMC) is a research hotspot in medium-voltage and high-voltage applications. The measurement offset error would cause an increase in the monitoring error of the submodule (SM) capacitance of the MMC, affecting the estimation accuracy of the SM capacitance monitoring. This paper proposes a capacitor monitoring strategy based on the offset error compensation, where two reasonable capacitor monitoring periods are selected in one fundamental period under the proposed voltage-balancing control (VBC) based on the virtual capacitor voltage (VCV) to compensate for the offset error impact on the capacitance monitoring. The proposed strategy can effectively eliminate the offset error impact on the capacitance monitoring, which ensures the accuracy of the SM capacitance monitoring in the MMCs. The effectiveness of the proposed monitoring strategy is confirmed by the simulations and experiments. [ABSTRACT FROM AUTHOR]

In industry, to improve the power factor in low-voltage power substations, a power factor controller (the most used method) can be installed which connects capacitors banks (connected, or not, with coils) in the electrical installation. The most important parameters of power engineering are the power factors that indicate the efficiency of energy use. Currently, many non-linear consumers (more single-phase than three-phase) are used on low voltages. Harmonics (currents and/or voltages) are the most important dynamic component of power quality, affecting electrical equipment performance and also reducing power factors. The purpose of this analysis is to increase the displacement power factor and to decrease the total harmonic distortion (for the current) in the conditions where there are linear and non-linear consumers, where the power factor must be improved with capacitors banks. Relevant different consumers have been selected for both the industry and the home sector, as follows: inductive motors that are linear, inductive consumers, compact fluorescent lamps that are non-linear, and capacitive consumers. This analysis was carried out depending on the number of steps used for the power factor controller, the values of the capacitors banks, the AC reactor (connected in series with all consumers), and the LC shunt filters. For a slight deformation regime, a large number of capacitors banks with different values ensure a finer adjustment of the displacement factor. The maximum number of steps that regulators can command should not necessarily be used (the reliability of the installation decreases with the increase in the number of capacitors banks), but a reduced number of steps can be used, which can lead to higher values of displacement power factors. To improve the deforming regime and to increase the displacement power factor, the use of LC shunt filters, connected to a small number of steps, will also increase the displacement power factor (over 0.9) and decrease the total harmonic distortion (up to 7–10%) for the current. Weaker results were obtained with AC reactors connected to the power supply phases of consumers and, if a larger number of stages were used, to which LC shunt filters were connected, these filters become difficult to calibrate (resonances occur). [ABSTRACT FROM AUTHOR]

Outstanding materials and novel device structures are key factors in satisfying the increasing demand for energy storage. Li‐ion capacitors, as one typical model of asymmetric supercapacitors, benefit from the battery's ultrahigh specific energy and supercapacitor's superlarge specific power to meet the balanced electrochemical energy storage requirements. The inherent and irreplaceable advantages make spinel lithium titanate an optimal candidate for power batteries and Li‐ion capacitors. However, upstream market volatility, including price spikes and supply shortages, tremendously threatens spinel lithium titanate's production, sale, and application. Lithium hydroxide hydrate is an alternative raw material to synthesize spinel lithium titanate synthesis, which can help address these concerns. The indirect production path generates high‐quality lithium carbonate as an intermediate product. Spinel lithium titanate is synthesized preferably via another economically and technically more efficient method that skips the isolation step after carboxylation. The electrochemical performance of the resulting spinel lithium titanate is evaluated to be better than that of commercial competitors. The spinel lithium titanate negative electrode‐based lithium‐ion capacitor achieves a specific energy of 89.5 Wh kg−1. These results demonstrate the success of efforts to find a feasible and affordable synthesis route to mitigate market risks. [ABSTRACT FROM AUTHOR]

Lithium fluoride (LiF) is currently a very popular dielectric material used as a passivation or transport layer in a variety of applications, especially in high-efficiency solar cells. Despite this, its conduction properties and interface behavior with silicon remain largely unexplored. In this work, a LiF metal–insulator–semiconductor (MIS) structure is fabricated and characterized, and its properties are compared to the well-understood aluminum oxide (Al2O3) MIS structure. First, a higher current density in LiF compared to Al2O3 is highlighted, as well as its PN junction-like behavior with n-type silicon (n-Si), being rather unconventional for a dielectric layer. C–V measurements showcase the likely presence of an interface defect, causing an increase in the apparent doping and a shift in the flatband voltage VFB by +70 meV. This defect is found to be of the acceptor type, which renders the interface fixed charge more negative and improves the field-effect passivation in the case of a negative Qf. Finally, a density of interface states D i t ≈ 2 × 10 11 cm − 2 eV − 1 was found for LiF/n-Si, which is a low value showing appropriate chemical passivation at the interface. Overall, this work enables us to shed more light on the interface properties of LiF on n-Si, which is an essential step toward its wider use in state-of-the-art solar cells and other silicon-based devices. [ABSTRACT FROM AUTHOR]

Lithium‐ion capacitors (LICs) are considered a promising next‐generation energy storage system with high energy density and power capability. The conductive additive is a passive and indispensable material in deciding the electrochemical performance of an energy storage device during high current charging and discharging processes. The incorporation of a suitable conductive additive into the layers of an electrode improves electronic conductivity. It reduces the internal resistance and polarization of the electrode resulting in the enhanced performance of the charge‐storage system. Herein, recovered graphite (RG) is reported from dead Li‐ion batteries as an excellent conductive additive that can improve the electronic conductivity of the electrode material. Compared with commercial conductive additive acetylene black (AB), the TiO2 anode material with 5% RG delivered a high discharge capacity of 163 mAh g−1 at a current rate of 0.15 A g−1 with a coulombic efficiency of ≈99% after 500 cycles in half‐cell assembly. The fabricated AC/TiO2@5%RG LIC displays an excellent electrochemical performance with a maximum energy density of ≈50 Wh kg−1 at a current density of 0.15 A g−1. Notably, the LIC rendered promising performance at different temperature conditions (0, 10, 25, and 50 °C). [ABSTRACT FROM AUTHOR]

This study proposes an optimal approach for enhancing the quality of a weak electrical power distribution system by utilizing thyristor‐controlled series capacitors (TCSC). The proposed approach considers various system components, including shunt capacitors and distributed generators that rely on renewable energy sources, which are characterized by uncertainty due to changing weather conditions. The proposed system maximizes the benefits of these components by updating its parameters to improve the distribution power system's quality under all operating conditions, which change due to the varying energy generated by the distributed generators and load changes. The optimal TCSC values are calculated for all operating conditions using the Hyper‐Spherical Search with graded objective functions management strategy (HSSA‐GOFMS) algorithm. The GOFMS converts all restrictions into objective functions with limits and prioritizes the search for objectives according to a sequential system of priorities. This strategy prevents the possibility of non‐convergence. The results demonstrate the effectiveness of the proposed approach in improving the performance quality of a weak electrical distribution system. The proposed strategy achieves the target voltage level limits within nominal values, even with the interference of the system with generators distributed at variable power levels. Furthermore, the proposed approach enhances the performance quality of the system under a wide range of load changes. [ABSTRACT FROM AUTHOR]

Due to different output voltages, capacitor voltage imbalance occurs between half-bridge sub-modules (HBSM) and full-bridge sub-modules (FBSM) in hybrid modular multilevel converters (MMCs) under a boosted modulation index (m). To address this issue, a capacitor voltage balancing method based on second-harmonic voltage injection is proposed in this paper. The mechanism of the proposed method is to eliminate the DC component in the charging power of sub-modules under the restriction that the HBSM cannot output negative voltage. The proposed method is divided into two cases according to m. Case 1 is used when m ≤ 1.4, while Case 2 is implemented when m > 1.4. When compared with similar capacitor voltage balancing methods, the proposed SVI method has a simpler structure that can greatly reduce the number of computations. Simulation and experimental results verify the effectiveness of the proposed capacitor voltage balancing method. [ABSTRACT FROM AUTHOR]

In order to improve the control performance and reliability of the pulse-width modulation (PWM) rectifiers in electric vehicle (EV) charging systems, the evaluation of DC bus capacitor health status is critical. In order to accurately monitor the health status of DC bus capacitors, a data-driven model fusion method is developed. In the method, multi-layer perceptron, random forest, and XGBoost are adopted as the base learners that produce separate row predictions. The second-level learner, support vector machine (SVM) accepts the outputs of the previous learners and integrates them into the final health status prediction. Meanwhile, the feature vector is constructed by only collecting the grid voltage, the grid current and the AC component of DC bus voltage. With the feature vector as input, the proposed method is able to accurately predict the health status of DC bus capacitor. Finally, we built a three-phase PWM rectifier as an experimental platform for validation. The experimental results verify that the proposed method fully utilizes the advantages of data-driven and model fusion, and achieves a high accuracy in the health state evaluation of DC bus capacitor. [ABSTRACT FROM AUTHOR]

The synthesis, morphology, and physical characterization of neat epoxy and DGEBA epoxy doped liquid crystal organic polymeric systems (EDLCPSs) have been investigated. Morphological properties of both systems were examined by SEM techniques. The small size of the LC droplets (0.224 μm) is also consistent with the presence of nitrile groups. The Fourier transform infrared (FTIR) and Raman spectra of the EDLCPSs detect a vibration band at 2229 cm−1 is attributed to C≡N stretching vibrational band. The optical band gap and refractive index have been studied using UV–visible spectroscopy. The calculated optical band gap of the EDLCP system shows a red shift as compared to neat epoxy. Our optical parameters were found to increase in the EDLCPSs. In the UV region, the systems block UV light up to a wavelength of about 380 nm which is an efficiency of UV light shielding devices. The photoluminescence (PL) is measured as a function of temperature for both systems. The integrated PL intensity decreases below 300 °C for the neat epoxy and lower than 220 °C for the EDLCPSs when increasing temperature is an effect related to the phonon diffusion (i.e., the photo-created pairs electron–hole). After 320°C, the neat epoxy system shows a completely inverted behavior when increasing temperature. On the other hand, the EDLCPSs revealed this comportment after 240 °C. The rise in thermal PL intensity was assigned to the variation in energy band gap transition and exchanges of the N1 and N2 deep levels nature. [ABSTRACT FROM AUTHOR]