Capacitor Cell Research Articles

Negative Joule heat effect on supercapacitor module

Joule heat as the main heat source in high-power operation of supercapacitor modules, needs to be carefully considered in thermal management. The sufficient discussion on the temperature characteristics of supercapacitor modules, especially those containing auxiliary electronic components during operation is of importance. Here we reported the Joule heat effect on a supercapacitor module integrated on a circuit board in the charge and discharge cycles by an in situ Infrared imaging method. Temperature rise of total components including wires, circuit board, welding pint, resistor and capacitor cell could be simultaneously imaged with a sensitivity of 0.2–0.3 °C. Upon charge–discharge cycles from 5C-60C, Joule heat on these electronic components was discovered. The thermal transfered from the connected wires to the circuit board and finally to the cell, which significantly increased the temperature rise (from 9.3 °C to 19.6 °C at 60C) and temperature difference (9.6 °C at 60C) of different capacitors in modules. Further simulation results indicated that Joule heat on the circuit board was 2–3 times that of the capacitors in the module. Such additional heat flow without suitable cooling system would result an accelerated capacitance decay of the module. Therefore, a suitable module structure and thermal management strategy needed to be designed to minimize the Joule heat generation of such electronic components.

Enhanced Oxidation Resistance and Interface Stability of Atomic-Layer-Deposited MoNx Electrodes via TiN Passivation for DRAM Cell Capacitor Applications.

The continuous miniaturization of dynamic random-access memory (DRAM) capacitors has amplified the demand for electrode materials featuring specific characteristics, such as low resistivity, high work function, chemical stability, excellent interface quality with high-k dielectrics, and superior mechanical properties. In this study, molybdenum nitride (MoNx) films were deposited using a plasma-enhanced atomic layer deposition (PEALD) employing bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride and NH3 plasma for DRAM capacitor electrode applications. Depending on the deposition temperatures of the PEALD MoNx films ranging from 200 to 400 °C, the Mo/N ratio and crystal structure varied, transitioning from the cubic NaCl-B1-type MoN phase with Mo/N ratio of 1.4 to the cubic γ-Mo2N phase with Mo/N ratio of 1.9. Notably, MoNx films grown at 400 °C exhibited low resistivity (435 μΩ·cm), a high work function (5.28 eV), and superior mechanical hardness (11.3 GPa) compared to ALD TiN films. Despite these excellent properties, the PEALD MoNx electrode demonstrated insufficient chemical stability, particularly in terms of oxidation resistance and interface quality with ALD HfxZr1-xO2 (HZO) films. This resulted in poor morphology and the formation of significant oxygen-deficient HZO layers (such as HfO2-x), leading to considerable degradation in the electrical performance of metal-insulator-metal (MIM) capacitors. To mitigate this issue, a thin (2.5-14 nm) ALD TiN layer was introduced as a passivation layer between the MoNx bottom electrode and HZO dielectric. The TiN-passivated MoNx (TiN/MoNx) electrode showed substantially enhanced oxidation resistance and reduced interfacial reactions with the HZO dielectric. Consequently, MIM capacitors with TiN/MoNx bottom electrodes demonstrated outstanding electrical performance, including excellent dielectric properties, low leakage current density, and high mechanical strength. Hence, this study proposes a promising candidates for storage nodes in the next-generation DRAM capacitors.

Inducing alternating magnetic fields for real-time non-contact fault localization within electric energy storage component arrays.

With the wide application of electric energy storage component arrays, such as battery cell arrays, capacitor arrays, and inductor arrays, their potential safety risks have gradually drawn the public attention. However, existing technologies cannot realize rapid, precise, and nondestructive localization of the faulty component within these large-scale arrays, especially for a component with an early stage short-circuit fault. To address this challenge, this paper proposes a magnetic field based method and realizes precise fault localization by inducing an alternating magnetic field from the target array, unlike previous research where a static magnetic field was induced. Through establishing a physical model of the short-circuit component as well as the whole array, a spatial filtering algorithm based on beamforming techniques is utilized to process the measured magnetic field data in real time. Both the simulation and experimental results demonstrate the capability of the proposed method in enhancing the security of electric energy storage component arrays. Within an imaging area of 80 × 80 mm2, the proposed method can accurately locate the faulty component out of a nine-component array, with an error of only 0.72mm for capacitors and 0.91mm for battery cells.

O-PHTHALALDEHYDE CROSS-LINKED CHITOSAN MEMBRANE AS A QUASI-SOLID-STATE ELECTROLYTE FOR SUPERCAPACITORS

This study reports a stepwise formation method of a chitosan membrane cross-linked with o-phthalaldehyde and its use as a polymer matrix in a quasi-solid-state-electrolytebased supercapacitor. The proposed method of cross-linking in chitosan solution and evaporation of the solvent yielded a homogeneous and durable chitosan-o-phthalaldehyde membrane, which, after dipping in an aqueous 2 M lithium sulfate solution, formed a quasi-solid-state-electrolyte (CS/OPAQSSE). The prepared CS/OPA-QSSE was then used in an electric double layer capacitor (EDLC) cell to study its electrochemical properties. The electrochemical performance of the EDLC cell was determined by using the electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charging/discharging techniques. The results showed that the EDLC cell with the CS/OPA-QSSE is a fully functional and efficient device. The specific capacitance values calculated for the CS/OPA-QSSE EDLC (up to 115 F g–1) always surpassed the reference cell based on a commercial glass fibre separator Therefore, the proposed chitosan modification can be considered as a future alternative to produce other polysaccharide-based materials for electrochemical use.

Smart composite based on fly ash cenospheres and transformer oil with switchable electrical conductivity

Fly ash cenospheres serve as an inexpensive filler for various composites. Coating their surface with metal significantly alters the properties of the resulting composites. In this study, aluminosilicate cenospheres receive a copper coating using a plasma method with magnetron sputtering. Based on these copper-coated cenospheres, composites are created, and their dielectric properties are investigated in a parallel plate capacitor cell under isotropic pressures ranging from 1 to 75 atm. Composites based on pure fly ash cenospheres exhibit pressure-invariant properties, including the dielectric constant and loss factor. However, for composites based on copper-coated fly ash cenospheres, an abrupt increase in electrical conductivity is observed as the pressure increases. Interestingly, significant changes in electrodynamics characteristics are not detected under the influence of anisotropic stress. The methodology tested in this work can be utilized for creating smart materials based on cenospheres.

Single source self balanced switched capacitor based singe phase nine level inverter

Multilevel inverters are becoming increasingly significant due to their ability to efficiently convert power in various applications such as renewable energy systems, electric vehicles (EVs), and industrial drives. The growing need for efficient power conversion in these areas has driven heightened interest in multilevel inverters. High inrush current is required for numerous applications, including variable frequency drives, single-phase or three-phase machine drives, locomotives, electric vehicles. However, managing this inrush current is crucial to prevent damage to the power source and other connected equipment, as well as to ensure smooth and reliable operation. The solution for this is to provide isolation between load and source. The proposed single phase switched capacitor multilevel inverter possess the feature of virtual isolation between the load and the source. This topology consists of a switched capacitor cell network and a multilevel inverter. In this work, a simplest architecture is used for the MLI section to reduce the number of switches. The MLI section consists of only eight switches. Although the switched capacitor network in this topology consists of a higher number of switches, the switches in the network carry only very low current, resulting in negligible losses. Additionally, the switched capacitor network is highly modular in nature. The proposed single-phase inverter can be converted to a three-phase multilevel inverter (MLI) by connecting identical units in each phase, with the reference sinewave signal for the pulse-width modulation technique derived from the corresponding phases. Consequently, this proposed topology is suitable for both low-power and high-power applications. This work demonstrates that self-voltage balancing of the level capacitors can be achieved without the need for auxiliary components.In this design, the level capacitors act as the source to the load and are charged through switched capacitors. The voltage THD in the suggested work is less than 5%, which is in accordance with IEEE 519 standards. High voltage gain, better load, and line regulation, are other significant advantages of this novel topology. Another feature of this work is simplicity in design and can be easily extended to higher voltage levels. Comprehensive simulation and experimental results are provided to validate the precise performance of the proposed multilevel inverter

Efficiency enhancement in a switched capacitor cell interleaved buck converter using GaN-FETs

Efficiency enhancement in a switched capacitor cell interleaved buck converter using GaN-FETs

Hybrid high step-up DC-DC converter based on quadratic and switched capacitor cells with reduced voltage stress across the switches

ABSTRACT In this paper, a high step-up DC-DC converter with high voltage gain is proposed. The propounded converter has a non-isolated configuration with a miscellany of three infrastructures, namely a {R1–1} switched quadratic cell, a switched capacitor (SC) cell and an auxiliary switch. The use of {R1–1} switched quadratic cell and SC improves the voltage gain of the converter and also reduces the voltage stresses of semiconductors. {R2–5} By adding an auxiliary switch, one degree of freedom is added to the output voltage gain control. Meanwhile, the efficiency is ameliorated, especially for high voltage gains. The duty cycle of the suggested structure is not only limited to changes but also can include a wide range of changes. In addition, the propounded structure provides higher voltage gains at lower duty cycles. Also, the voltage stress of semiconductor elements is reduced compared to the structures based on switched inductor/capacitor and quadratic converters. The principle of operation and steady-state analysis are discussed in detail. Also, a laboratory prototype is built to validate claim made. The results indicate that the use of an auxiliary switch helps to progress the voltage gain.

A Molecular Adsorption Concept for Increasing Energy Density of Hybrid Supercapacitors.

In this report, we demonstrate that high-capacity hybrid supercapacitors can be realized by utilizing iron azaphthalocyanine (FeAzPc-4N) adsorbed activated carbons (ACs) as an electrode due to the combination of the electric double layer of activated carbon surfaces and redox reactions of FeAzPc-4N molecules. By increasing the mixing ratio of FeAzPc-4N with ACs, a maximum capacity of 907 F/gAC is achieved, also enabling rapid charging and discharging at 20 A/g. The revelation of the capacitor electrode's durability through 20 000 cycles of charging and discharging is realized, and the capacitor cell had sufficient output power to illuminate LEDs. This concept illustrates the potential for enhancing capacitor performance by immobilizing redox-active species.

Optimizing Electrode Efficiency in Lithium Titanate: Investigating the Impact of Electrolyte Additives on Cylindrical Li‐Ion Capacitor Cells

Recent advancements in lithium‐based energy storage focus on new electrode materials for lithium‐ion batteries (LIBs) and capacitors. Lithium titanate (LTO) emerges as a key player, offering minimal volume change, rapid charging, and enhanced safety. A critical discovery is the formation of a solid electrolyte interphase (SEI) layer on LTO electrodes, especially with electrolyte additives, improving electrochemical performance. This study investigates additive effects on LTO. Large‐scale Li‐ion capacitors (LIC) of LTO//activated carbon (AC) are crafted and evaluated. Notably, adding just 1% of methylene methanedisulfonate (MMDS) or fluoroethylene carbonate (FEC) to a 1 m LiPF6 electrolyte markedly increases capacities and maintains performance over 500 cycles, outperforming other additives. These additives also boost large‐scale capacitor capacities, showing exceptional stability for over 1600 cycles. This underlines the potential of customized electrolyte additives in elevating LTO‐based energy storage, leading to more durable and efficient lithium‐based solutions.

ISOLATED PINEAPPLE PEEL MICROCELLULOSE AS A MATRIX FOR POLYPYRROLE-BASED CAPACITOR

This study investigates the viability of utilizing microcellulose extracted from pineapple peel waste as a sustainable and cost-effective matrix material for polypyrrole (PPy)-based capacitors. A novel PPy/microcellulose composite was synthesized with varying pyrrole volumes (1-2 mL) and characterized using Fourier Transform Infrared (FTIR) and X-ray diffraction (XRD) analyses. FTIR analysis confirmed successful cellulose isolation, while XRD indicated a similarity between the extracted pineapple peel and commercial cellulose. Capacitor cells were fabricated using the synthesized composites, and their capacitance performance was evaluated. Notably, cells containing 2 mL of PPy exhibited the highest capacitance values. Additionally, the source of cellulose had minimal influence on the resulting capacitance. This study suggests that microcellulose derived from pineapple peel waste holds promise as a sustainable alternative to traditional matrix materials for high-performance capacitors.

Significantly enhanced ion‐migration and sodium‐storage capability derived by strongly coupled dual interfacial engineering in heterogeneous bimetallic sulfides with densified carbon matrix

AbstractThe development of highly efficient sodium‐ion batteries depends critically on the successful exploitation of advanced anode hosts that is capable of overcoming sluggish reaction kinetics while also withstanding severe structural deformation triggered by the large radius of Na+‐insertion. Herein, a hierarchically hybrid material with hetero‐Co3S4/NiS hollow nanosphere packaged into a densified N‐doped carbon matrix (Co3S4/NiS@N‐C) was designed and fabricated utilizing CoNi‐glycerate as the self‐sacrifice template, making the utmost of the synergistic effect of hetero‐Co3S4/NiS with strong electric field and rich reaction active‐sites together with the densified outer‐carbon scaffolds with remarkable electronic conductivity and robust mechanical toughness. As anticipated, as‐fabricated Co3S4/NiS@N‐C anode affords remarkable specific capacity, prolonged cycle lifespan up to 2 400 cycles with an only 0.05% fading each cycle at 20.0 A g−1, and excellent rate feature (354.9 mAh g−1 at 30.0 A g−1), one of the best performances for most existing Co3S4/NiS‐based anodes. Ex situ structural characterizations in tandem with theoretical analysis demonstrate the reversible insertion‐conversion mechanism of initially proceeding with Na+ de‐/intercalation and superior heterogeneous interfacial reaction behavior with strong Na+‐adsorption ability. Further, sodium‐ion full cell and hybrid capacitor based on Co3S4/NiS@N‐C anode exhibit impressive electrochemical characteristics on cycling performance and rate capability, showcasing its outstanding feasibility toward practical use.

Optimized diagnosis of local anomalies in charge and discharge of solar cell capacitors

BackgroundWith the increasingly serious environmental pollution and natural environment damage, renewable energy such as solar cells have gradually become the key to change this situation. Therefore, the local abnormal diagnosis of the charge and discharge of solar cell capacitors is particularly important. ObjectiveTo extend the life of ultracapacitors by resolving the issue of their low detection rate and enhancing the capacity to recognize fault diagnosis factors. A novel approach to charging and discharging, as well as the diagnosis of local anomalies, is put forth, utilizing switching networks. MethodsBy controlling the capacitors of multiple solar cells and supercapacitors to work together, it is possible to compensate for the shortage of photovoltaic power. The performance of fault diagnosis is optimized by combining principal component analysis and binary K-means clustering, which completes the fault diagnosis of capacitors. ResultsThe experimental results show that the research method can increase the maximum output power of photovoltaic by 32.9% under multi-layer shadows. In the charging state of the training set, the number of abnormal capacitors is 6, and the number of normal capacitors is 12, and both of them are in accordance with the preset value. The number of abnormal capacitors and normal capacitors in the discharge state is the same as that in the charging state, which is also 6 and 12. ConclusionThe research method can effectively address the issue of unbalanced energy storage battery packs and minimize the impact of local shadows on photovoltaic systems. In comparison to fuzzy C-means clustering, this method requires fewer iterations, enables faster fault diagnosis, and produces more accurate clustering results. It can provide technical support for diagnosing local abnormalities in the charging and discharging of solar cell capacitors.

An Extensible Non-isolated Enhanced Gain DC–DC Converter Integrating Switched Capacitor Cell for FCEV

An Extensible Non-isolated Enhanced Gain DC–DC Converter Integrating Switched Capacitor Cell for FCEV

Non-Isolated High Gain Interleaved DC–DC Converter with Voltage Multiplier and Switched Capacitor for Renewable Energy Systems

A novel non-isolated high-gain DC–DC converter for green energy employment is presented and analyzed. The proposed converter comprises a switched capacitor cell, passive clamp circuit, coupled inductors, and voltage multiplier unit. An interleaved boost converter (IBC) is placed on the input side of the proposed design. The voltage multiplier unit (VMU) with the secondary windings of the coupled inductors is located on the load side. It is used to accomplish interleaved power storage. The leakage energy of coupled inductor is recirculated to the load side, and the reverse recovery problem of diodes is effectively suppressed. As a result, a low-on-state resistance power switch with a low voltage rating is employed and minimizing conduction losses. The presented topology is suitable for sustainable energy applications due to its low operating duty cycle, high voltage conversion ratio, and higher efficiency. The output voltage causes substantially low voltage stress on semiconductor switches and passive elements. This proposed paper deals with simulation, parameter selection, experimental design, results and discussion. The simulation is verified using MATLAB/Simulink with a DC voltage of 30–517[Formula: see text]V. To validate the design analysis, a 1.5-kW experimental prototype is designed with a switching frequency of 10[Formula: see text]kHz and attained an efficiency of 96.07%.

Analysis of single switch step up DC-DC converter with switched inductor-switched capacitor cells for PV system

The presented work exhibits high gain and increased efficiency for DC-DC converter. Additionally, this topology significantly improves the voltage conversion ratio when compared with other DC-DC converters reported recently. The non-existence of high frequency transformer ensures compactness and low cost and henceforth, it is apt for clean energy applications. The analysis of the high gain converter in steady state is carried out in continuous conduction mode (CCM). Initially, the proposed converter performance is analyzed using MATLAB/Simulink platform and prototype of the same with a power rating of 200 V, 100 W is built and tested. The reliability and robustness of the converter is perceived from the experimental results and peak efficiency achieved is around 93%.

Mitochondrial function and reactive oxygen species production during human sperm capacitation: Unraveling key players.

Sperm capacitation is a critical process for male fertility. It involves a series of biochemical and physiological changes that occur in the female reproductive tract, rendering the sperm competent for successful fertilization. The precise mechanisms and, specifically, the role of mitochondria, in sperm capacitation remain incompletely understood. Previously, we revealed that in mouse sperm mitochondrial activity (e.g., oxygen consumption, membrane potential, ATP/ADP exchange, and mitochondrial Ca2+ ) increases during capacitation. Herein, we studied mitochondrial function by high-resolution respirometry (HRR) and reactive oxygen species production in capacitated (CAP) and non-capacitated (NC) human spermatozoa. We found that in capacitated sperm from normozoospermic donors, the respiratory control ratio increased by 36%, accompanied by a double oxygen consumption rate (OCR) in the presence of antimycin A. Extracellular hydrogen peroxide (H2 O2 ) detection was three times higher in CAP than in NC sperm cells. To confirm that H2 O2 production depends on mitochondrial superoxide ( ) formation, we evaluated mitochondrial aconitase (ACO2) amount, activity, and role in the metabolic flux from the sperm tricarboxylic acid cycle. We estimated that CAP cells produce, on average by individual, (59 ± 22)% more in the steady-state compared to NC cells. Finally, we analyzed two targets of oxidative stress: lipid peroxidation by western blot against 4-hydroxynonenal and succinate dehydrogenase (SDH) activity by HRR. We did not observe modifications in lipoperoxidation nor the activity of SDH, suggesting that during capacitation, the increase in mitochondrial H2 O2 production does not damage sperm and it is necessary for the normal CAP process.

High gain interleaved DC-DC converter with ripple-free input current and low device stress

ABSTRACT A non-isolated DC-DC converter which yields high voltage gain and suitable for photovoltaic (PV) applications is described in this research article. The high gain converter proposed in this paper is synthesised by combining several voltage gain extension techniques viz. coupled inductors, voltage-lift capacitor, and diode-capacitor multiplier (DCM) cells. Since the input stage is interleaved, and the switches are operated complimentarily, the source current ripple is nullified and switch current rating is minimised. Due to the hybrid voltage gain extension techniques adopted while synthesising the converter, the voltage stress on the switches is only 10.5% of the output voltage. To validate the proposed concept, experimental results are obtained from 18 V-380 V, 150W prototype converter which is operated at 50 kHz. The proposed converter yields a voltage gain of 21.11 at 92.83% efficiency under full-load condition. During closed-loop operation, the proposed converter quickly settles down to its nominal output voltage of 380 V when the input voltage and load current values are subjected to step variations. The superior features of the proposed converter are highlighted by comparing it with similar and recent state-of-the art high gain converters.

Implementation of Non-Isolated High Gain Interleaved DC-DC Converter for Fuel Cell Electric Vehicle Using ANN-Based MPPT Controller

A high conversion ratio DC-DC converter is crucial for fuel cell electric vehicles (FCEV). A fuel cell-based non-isolated high gain integrated DC-DC converter for electric vehicles is proposed in this paper. The system comprises an interleaved boost converter (IBC) at the source end, a switched capacitor cell, coupled inductors, a passive clamp circuit, and a voltage multiplier circuit (VMC). Its significance is to achieve the voltage conversion gain of 12.33 at a conversion ratio of 0.45. The idea is to use a proton exchange membrane fuel cell to power electric vehicles through a high-gain DC-DC converter. The use of an ineffective MPPT can result in lower energy conversion efficiency. Thus, this system incorporates a maximum power point tracking (MPPT) controller based on a neural network, which relies on the radial basis function network (RBFN) algorithm to track the maximum power point of the PEMFC accurately. The comparative study of the fuel cell electric vehicle (FCEV) structure with the RBFN-based MPPT technique was evaluated with that of the fuzzy logic technique using the MATLAB/Simulink platform (R2021b (MATLAB 9.11)). A 1.5 kW experimental prototype is designed with a switching frequency of 10 kHz to validate the design analysis, and its pursuance is compared between RBFN and FLC-based controllers. This manuscript will be a significant contribution towards evidencing a sustainable environment.

A Variable Speed Induction Motor Drive With 24-Stepped Voltage Waveform Throughout Modulation Range

Multi-level inverters produce low order harmonics in over-modulation region, which can be eliminated by generating polygonal space vector structure. A variable speed induction motor drive to generate 24-stepped voltage waveform throughout modulation range is proposed in this article. An open-end winding configuration induction motor (OEIM) is fed with primary and secondary inverter from both the ends of OEIM and generates a 24-stepped phase voltage. The proposed scheme also produces 96-stepped phase voltage waveform at extreme modulation index with highly suppressed higher order harmonics and excellent quality phase voltage. The motor terminal sees a 24-stepped waveform at all speeds, devoid of low order harmonics up to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$19^{th}$</tex-math></inline-formula> order. The scheme does not require vector timing calculation due to availability of highly dense 24-sided polygonal structure. Primary and secondary inverters are derived by cascading flying capacitor and CHB cells. Experimental verifications are performed on in-house developed laboratory prototype. Motor phase voltage and phase current waveforms during steady state and transient conditions justifies performance of the proposed scheme. Dynamic performance and floating capacitors voltage balancing method are verified by experimental results.