Faraday Cage Research Articles

Self-healing of surface defects on Zn electrode for stable aqueous zinc-ion batteries via manipulating the electrode/electrolyte interphases

The reversibility and stability of aqueous zinc-ion batteries are largely limited by inevitable parasitic reactions at the interface and uncontrollable dendrite growth. Inspired by self-healing smart electronic materials, we propose a confinement strategy with gelatin, an amphiphilic macromolecule, as additive to regulate the deposition behavior of Zn ions and utilize the dendrites to fill the surface defects formed by inevitable interfacial parasitic reactions. Absorbed gelatin molecules impede H2O reaching Zn electrode surface to enhance the anticorrosion behavior and adjust the local pH value, which is a “smart” way to stabilize the electrode/electrolyte interphase. Additionally, the confined effect of absorbed gelatin molecules on Zn2+ and “electrostatic shield” formed from positive charged –CN3H5+ suppress 2D diffusion and accumulation of Zn2+, guiding Zn continuously depositing inside the defect during electrochemical cycling, then self-healing of electrode surface defects is achieved. Under the synergetic effects of these merits, Zn electrode demonstrates almost unchangeable surface after soaking in the electrolyte for 10 days, and stably cycle more than 1100 h at 0.5 mA cm−2 and 1300 h at 3.0 mA cm−2 in symmetric cell. In addition, the full batteries using the base electrolyte with 0.5 and 1.0 g/L gelatin can stably cycle for 3000 cycles.

Equivalent Circuit Model of a Pulse Planar Transformer and Endurance to Abrupt dv/dt

Wide-bandgap (WBG) semiconductor materials offer faster and more reliable power electronic components in electric energy conversion systems. However, their faster switching speed and abilities to operate at higher frequency than silicium devices have brought new challenges, such as electromagnetic interference (EMI) issues. In gate driver applications, EMI issues must be tackled given the close proximity between gate driver systems and WBG power modules. This article focuses on planar pulse transformers for gate drivers in high power applications (3.3 kV, 500 A SiC module). This article tries to give a standard procedure to design, then, simulate pulse transformers with their electrostatic shielding. First, a design guideline using Altium designer is proposed to respect the European standards. A method to extract the transformer design from Altium to Ansys is also proposed. Finally, a frequency analysis is discussed to use in Ansys simulations and parameters extraction. Tests have been performed to check the proposed transformer’s electromagnetic compatibility immunity under a 125 kV μs^−1 common mode transient immunity test.

An organic imidazolium derivative additive inducing fast and highly reversible redox reactions in zinc-bromine flow batteries

In zinc-bromine redox flow batteries (ZBBs), the weak molecular structure and stability of bromine-complexing agent (BCA) can sometime negatively affect battery's performance. To address this issue, this paper introduces a 1,2-dimethyl-3-ethylimidazolium bromide (DMEIm∙Br, C7H13BrN2), comprising planar molecular structure with strong molecular-polarizability and low steric hindrance. The effectiveness of the DMEIm∙Br is compared and verified with those of two popular BCAs through various electrochemical experiments including full-cell tests for 200 cycles. Experimental results show that the DMEIm∙Br significantly contributes to apparently enhancing reaction kinetics and reversibility of Zn2+/Zn(s) and Br−/Br2 redox couples by inducing highly reversible zinc-plating/stripping (by strong electrostatic shielding effect) and bromine-capture/release (along with strong bromine-binding strength) in anolyte and catholyte solutions, respectively. The superior chemical and electrochemical properties are clearly demonstrated by the fact that the DMEIm∙Br-supported solution in ZBBs exhibits 5.53 (24.19) and 7.29 (16.99) % higher current and voltaic efficiencies than the pristine solution at the temperature of 25 (60) °C, respectively. It also exhibits remarkably improved discharge-capacity retention of averagely 99.17% for 200 cycles along with a slight discharge-capacity loss of only 1.46% vs. 1st cycle at 200th cycle, even at the high temperature of 60 °C.

Design optimization of slit aperture Faraday shield for RF ion source in CRAFT NNBI system

The Faraday shield (FS) is a key part of the radio frequency (RF) ion source for high power neutral beam injection system. The RF transfer efficiency and power loss ratio of the driver with two different types of FS are analyzed using a finite element model. These two types of FS are divided into inclined shape slits and Z shape slits, and each slit shape can be subdivided into six types. It is found that the change of the slit shape on the FS has little effect on the RF transfer efficiency and the power loss ratio. For the six drivers with inclined shape FS slit, the difference in RF efficiency between them does not exceed 1%, and the difference in the power loss ratio on the FS does not exceed 1.2%; for the six drivers with Z shape FS slit, the change in the RF efficiency does not exceed 0.3%, and the change in power loss ratio on the FS does not exceed 0.4%. Meanwhile, taking electrons as the research object, the interception ability of 12 kinds of FS to particles was compared, and the optimal structure of the FS slit is determined.

A novel property enhancer of clean fracturing fluids: Deep eutectic solvents

Fracturing fluid properties are closely related to the oil recovery of unconventional reservoirs. In the meantime, deep eutectic solvents (DESs) have provided a new method to improve the properties of clean fracturing fluids (CFFs) due to their low-toxicity raw materials and mild synthesis conditions. In this work, DESs were developed as the enhancers to intensify rheological characteristics and spontaneous imbibition performance of CFFs. The adjustment of hydrogen bond donors (HBDs) can effectively regulate the rheological characteristics of CFFs. The DES composed of choline chloride (ChCl) and malonic acid (MA) can significantly increase the viscosity of CFF from 38.1 mPa·s to 60.1 mPa·s, the shear resistance and viscoelastic modulus were both improved. The interactions between HBDs and sodium p-toluenesulfonate (TsONa) anion has an influence on the electrostatic shielding of TsONa anion for OAHSB, which further determines the strength of micelle networks. For the spontaneous imbibition of CFFs, DESs improved the imbibition efficiency from 33.0% in 98 h to 40.1–47.2% in 78–90 h through the reduction of oil–water interfacial tension and oil viscosity, change of oil-contacting surface wettability and the increase of core porosity and permeability. The DESs here provide a novel strategy to enhance CFF properties in an environmentally friendly and efficient way.

Selecting an Optimal Faraday Cage To Minimize Noise in Electrochemical Experiments.

The ubiquitous Faraday cage, an experimental component particularly essential for nanoelectrochemical measurements, is responsible for neutralizing noise introduced by electromagnetic interference (EMI). Faraday cage designs abound in the literature, often exhibiting varying thicknesses, mesh sizes, and base materials. The fact that the Faraday cage composition most often goes unreported underscores the fact that many electrochemical researchers assume a 100% EMI reduction for any given design. In this work, this assumption is challenged from a theoretical and empirical perspective by highlighting the physical principles producing the Faraday effect. A brief history of the Faraday cage and a simplified theoretical approach introduce fundamental considerations regarding optimal design properties. In practice, time-domain noise profiles and corresponding Fourier transform frequency domain information for custom-built Faraday cages reveal that maximally conductive cages provide more optimal EMI exclusion.

Solving EMC problems in the design of new HV test laboratory

The paper deals with solving electromagnetic compatibility (EMC) problems in the design of a new, case study, industrial high voltage test laboratory, intended to be used for testing of transformers and other apparatus up to 550 kV rated voltage. Modern high voltage test facilities are equipped, apart from primary test devices like AC, DC and impulse voltage generators etc., also with sophisticated numerical measuring instruments and informatics technology. Since such devices are sensitive to transient overvoltages, the highest degree of EMC is to be secured. This can be achieved by proper earthing and screening of test laboratory, what shall be designed in a way to satisfy all requirements conditioned by building lightning protection, personal protection and system earthing, avoiding electromagnetic compatibility disturbances at the same time. One of the main tasks is solving electromagnetic compatibility problems caused by outdoor electromagnetic disturbances originating from various unknown sources. Those disturbances and interferences may seriously influence measuring accuracy and readings of test devices, what consequently leads to false results. The stated is especially relating to partial discharge measurements. As to avoid such disturbances, the laboratory shall be completely screened with a net forming optimally designed Faraday cage. On the other hand, at high voltage tests with impulse voltages, especially with chopped tail waves, steep transient overvoltages may be generated. As a consequence, high transient potential differences between particular points along the earth electrode may occur, what can even lead to flashovers between parts of it. Therefore is of utmost importance to provide proper earthing and low inductance current return path for impulse high voltage test equipment where high frequency transients are to be anticipated. Improper earthing and bonding may result, apart from mentioned flashovers, in severe induced voltages in secondary cables with consequential influence on test results, possible destruction of measuring instruments and hazardous touch voltages for personnel. For analyzing transient potential differences, it is important to model, with maximum accuracy, impulse test circuit (impulse generator, chopping spark gap, voltage divider, Faraday cage, fundament earth electrode, earthing strips, earthing rods etc.). Magnitude of transient potential difference between particular points is proportional to earth electrode inductance, i.e. low inductance of earth electrode will result in decrease of transient potential difference.

A Self-Regulated Electrostatic Shielding Layer toward Dendrite-Free Zn Batteries.

Although aqueous Zn batteries have become a more sustainable alternative to lithium-ion batteries owing to their intrinsic security, their practical applications are limited by dendrite formation and hydrogen reactions. The first application of a rare earth metal type addition to Zn batteries, cerium chloride (CeCl3 ), as an effective, low-cost, and green electrolyte additive that facilitates the formation of a dynamic electrostatic shielding layer around the Zn protuberance to induce uniform Zn deposition is presented. After introducing CeCl3 additives, the electrochemical characterizations, in situ optical microscopy observation, in situ differential electrochemical mass spectrometry, along with density functional theory calculations, and finite element method simulations reveal resisted Zn dendritic growth and enhanced electrolyte stability. As a result, the Zn-Zn cells using the CeCl3 additive exhibit a long cycling stability of 2600 h at 2mA cm-2 , an impressive cumulative areal capacity of 3.6 Ah cm-2 at 40mA cm-2 , and a high Coulombic efficiency of ≈99.7%. The fact that the Zn-LiFePO4 cells with proposed electrolyte retain capacity significantly better than the additive-free case is even more exciting.

A cation-anion synergetic additive achieving long-term stability of lithium metal anode

Lithium metal anode (LMA) has been regarded as the “Holy grail” among next-generation anode materials, which are severely enslaved to its poor cycling stability. Many problems such as Li dendrites and dead Li are involved in the cycling process, thus a protection strategy with a single function is difficult to achieve long-term stability of LMA. Herein, we developed a cation-anion synergetic additive, cesium triiodide (CsI3), to inhibit Li dendrite growth and eliminate dead Li. The addition of Cs+ could play a role in electrostatic shielding to homogenize the deposition progress of Li+, and the further introduction of I3− could react with the inactive Li2O on the surface of the Li to revitalize dead Li. The CsI3-added carbonate or ether electrolyte exhibited excellent cycling stability in a series of electrochemical performance tests, such as the Li-Cu half cell (over 600 cycles), Li-LiFePO4 (LFP, 11.5 mg cm−2, 50 μm Li, 1 μL mg−1 electrolyte) full cells (82% retention over 450 cycles), and Cu-LFP anode-free cells (80% retention over 110 cycles).

Study on Interface Thermodynamic Mechanism of Membrane Fouling in flat sheet ceramic membrane treating Oilfield Produced Water

In this study, a flat sheet ceramic membrane experimental device was constructed, and the thermodynamics of membrane fouling interface was studied for oilfield produced water. The flux of ceramic membrane in three kinds of model solutions were measured with time, as well as the surface tension, contact Angle and Zeta potential of solid. The thermodynamic mechanism of membrane fouling interface combined with XDLVO theory were explored for three kinds of model solutions. The thermodynamic study of the interface of ceramic plate membrane shows that the total interaction energy between membrane and oil droplets decreases with the increase of the distance between two interfaces at initial stage of membrane fouling, and finally transforms from the mutual attraction to the mutual repulsion. The total interaction energy between reservoir and oil droplet is shown as mutual attraction, and the total interaction energy decreases with the increase of the distance between reservoir and oil droplet interface. The zeta potential of crude oil was affected by salinity to some extent. The electrostatic shielding effect of the salt ions leads to a decrease in the ζ-potential of the three solutions. They are in the order: model solution A > model solution B > model solution C. This leads to a decrease in the electrostatic interaction (EL). And since the oil layer has the same composition as the oil droplets, the EL interactions in the three solutions can behave as mutual repulsion.

Electroanalytical measurements of lanthanum (III) chloride in molten calcium chloride and molten calcium chloride and lithium chloride

Cyclic voltammetry (CV), square wave voltammetry (SWV) and other electroanalytical methods have been applied to molten chloride salts to study metal ion behavior. These studies have been useful for understanding and optimizing the electrowinning of metals. Notable ions that have been studied are rare earth and actinide metal ions in LiCl-KCl salts. However, the behavior of lanthanum (La3+) ions in some molten chlorides or chloride mixtures (e.g., CaCl2) has not been studied. CV experiments were conducted to evaluate La3+ behavior in CaCl2-LiCl and CaCl2 and were compared to La3+ behavior in LiCl-KCl and CaCl2-NaCl eutectics from other studies. The electrochemical reaction was checked for reversible, quasi-reversible, and irreversible transitions in scan rate by examining the relationship between the scan rate applied and the peak current and potential for La3+ reduction. Properties such as diffusion coefficient (Do) and electrons exchanged (n) were calculated from data. The electrochemical setup was also checked for radial diffusion based on the calculated La3+ diffusion coefficient and electrode radius, which led to the observation that natural convection possibly affected the La3+ reduction peak at low scan rates. For more accurate electroanalytical measurements of La3+ reduction, CV curves with and without LaCl3 added to CaCl2 and CaCl2-LiCl were compared to establish baselines for the La3+ reduction peak. The impact of resistance (IR) compensation on the La3+ reduction peak was also explored. Techniques and practices that improved electroanalytical measurements include placing the electrolytic cell in a Faraday cage, distancing electrodes from the heating coils, and melting the chlorides twice prior to measurements.

Electronic Structure and External Electric Field Modulation of Polyethylene/Graphene Interface.

Polymer nanocomposites can serve as promising electrostatic shielding materials; however, the underlying physical mechanisms governing the carrier transport properties between nanofillers and polymers remain unclear. Herein, the structural and electronic properties of two polyethylene/graphene (PE/G) interfaces, i.e., type-H and type-A, have been systematically investigated under different electric fields using first principle calculations. The results testify that the bandgaps of 128.6 and 67.8 meV are opened at the Dirac point for type-H and type-A PE/G interfaces, respectively, accompanied by an electron-rich area around the graphene layer, and a hole-rich area around the PE layer. Moreover, the Fermi level shifts towards the valence band maximum (VBM) of the PE layer, forming a p-type Schottky contact at the interface. Upon application of an electric field perpendicular to the PE/G interface, the Schottky contact can be transformed into an Ohmic contact via the tuning of the Schottky barrier height (SBH) of the PE/G interface. Compared with the A-type PE/G interfaces, the H-type requires a lower electric field to induce an Ohmic contact. All these results can provide deeper insights into the conduction mechanism of graphene-based polymer composites as field-shielding materials.

An efficient electrolyte additive of tetramethylammonium sulfate hydrate for Dendritic-Free zinc anode for aqueous Zinc-ion batteries

Recently, zinc metal has been considered as a promising metal anode for aqueous rechargeable metal ion batteries due to its low electrochemical potential and high theoretical capacity. However, zinc metal suffers from hydrogen evolution reaction (HER) and dendrite growth during plating/stripping. Here, we propose a low-cost, effective and non-toxic electrolyte additive, tetramethylammonium sulfate hydrate (TMA2SO4), as a simple cationic surfactant additive for zinc-ion batteries, to trigger the smooth Zn deposition during charging and discharging process. It is found that TMA2SO4 enable the realization of the deposition of Zn ions along the surface of zinc foil laterally without stacking and thus dendrite growth and side reactions are greatly mitigated by the electrolyte additive of TMA2SO4 even when the amount of the additive is as low as 0.25 mM. As a result, the TMA2SO4 additive induces excellent cycling stability over 1800 h at the current density of 0.5 mA cm−2 with the limited capacity of 0.5 mAh cm−2 for the Zn-Zn symmetrical cell. Moreover, the electrolyte with TMA2SO4 can well match with MnO2 cathode, which achieves the high initial capacity of 181.3 mAh g−1 at 0.2 A g−1 and long-term cycling stability with the capacity retention of 98.72 % after 200 cycles for the Zn/MnO2 full cell. This work provides a general electrolyte design strategy to suppress zinc dendrite growth and side reactions to achieve long-lifespan zinc metal anodes for aqueous zinc ion batteries by electrostatic shielding effect.

Metal Nitrate Embedded Polymeric Interlayer for Improving Cycling Stability of Li Metal Anode

Among secondary batteries using lithium, the use of lithium metal anodes for high capacity has become a hot topic. However, in lithium metal anodes, there is a major problem of dendritic growth and research are actively underway to address the issue. And it is reported that it is possible to improve the stability of Li metal anode by facilitating the movement of lithium ions through various additives to suppress dendritic growth and to make robust and stable SEI layer. To address the issue of dendritic growth of Li, using cesium nitrate is selected to improve the stability of the anode based on a mechanism by which a nitrogen-rich compounds lithiophilic to transport Li ion uniformly are formed in the SEI layer. And also the cesium element induces an cation electrostatic shielding effect while lithium metal is deposited and grown in the anode. In addition, since metal nitrates have very low solubility in carbonate-based electrolytes, polymer nanofiber-interlayer is synthesized by electrospinning to support metal nitrate and supply nitrate continuously and stably, while interlayer does not interfere with the movement of lithium ions through the nanofiber layer. In summary, a metal nitrate embedded polymer nanofiber layer is synthesized through an electrospinning method, then stabilization of a lithium surface and stability of a lithium metal anode are obtained by using an intermediate layer, and a relationship between an additive and SEI formation is identified at a limited solubility in carbonate electrolytes. The study result demonstrates that the lifetime of symmetric Li-Li cells and full cell with LCO cathodes improved greatly. And the deposition morphology of Li become dendrite-free and more uniform.

Lamb Wave Wireless Communication Through Healthy and Damaged Channels With Symmetrical and Asymmetrical Steps and Notches.

Data transmission through solid metallic channels is recommended in certain industries where no other options are proposed, such as nuclear, aerospace, and smart vehicles. In addition to the Faraday shielding effect of electromagnetic waves, another issue related to damage presence due to mechanical loads exists. Severe damage in the transmission channel leads to signal loss at the receiver. For this sake, ultrasonic guided waves, such as Lamb waves, maybe a good substitute since they can propagate through long distances in solid metallic structures. The scope of this work is to build a reliable, reproducible, and high data-rate wireless communication experimental platform, using ultrasonic guided waves, through healthy and damaged plates for industrial usage. The target is to compensate at first for the effect of dispersion, reverberation, scattering, and boundary reflections for the healthy plate. The novelty of this work falls within the performance analysis of the demodulation algorithm based on cross-correlation combined with binary phase-shift keying (BPSK), using a finite-element simulation through healthy and damaged plates with different depths of symmetrical and asymmetrical notches (SN and AN) and steps based on the bit error percentage (BEP). Furthermore, another contribution related to the impact of multiple reflections and mode conversions caused by symmetrical and asymmetrical steps and notches is taken into account. After this, numerical results are validated using an ultrasonic guided wave experimental platform. Results based on BEP analysis prove that the algorithm has successfully compensated for the effect of dispersion and boundary reflections for the healthy plate and multiple reflections and mode conversions for the damaged ones. A highly effective data rate of up to 350 kb/s can be reached even in the presence of severe damage in the transmission channel.

Effects of Layer-to-Layer Coupling on the Total-Ionizing-Dose Response of 3-D-Sequentially Integrated FD-SOI MOSFETs

Total-ionizing-dose (TID) responses are investigated for 3-D-sequentially integrated fully depleted silicon-on-insulator (FD-SOI) MOSFETs. Strong layer-to-layer coupling of TID response is observed. The simultaneous application of positive bias to the gate of the bottom-layer device and negative bias to the top-layer device leads to the maximum enhancement of positive charge trapping in the top-layer device and the intermediate dielectric layer. This enhancement is due to the upward-directed electric field in the intermediate dielectric layer under these bias conditions. In contrast, electrostatic shielding prevents the gate bias of the top-layer device from affecting the response of the bottom-layer device, as confirmed by experiments and technology computer-aided design (TCAD) simulations. Effects of layer-to-layer coupling are less significant for postirradiation-biased annealing.

Boosted Productivity in Single-Tile-Based DNA Polyhedra Assembly by Simple Cation Replacement.

Cations such as divalent magnesium ion (Mg2+ ) play an essential role in DNA self-assembly. However, the strong electrostatic shielding effect of Mg2+ would be disadvantageous in some situations that require relatively weak interactions to allow a highly reversible error-correcting mechanism in the process of assembly. Herein, by substituting the conventional divalent Mg2+ with monovalent sodium ion (Na+ ), we have achieved one-pot high-yield assembly of tile-based DNA polyhedra at micromolar concentration of tiles, at least 10 times higher than the DNA concentrations reported previously. This strategy takes advantage of coexisting counterions and is expected to surmount the major obstacle to potential applications of such DNA nanostructures: large-scale production.

Methods for Enhancing the Electrical Properties of Epoxy Matrix Composites

This paper presents ways to modify epoxy resin matrix composites to increase their electrical conductivity. Good electrical properties are particularly important for materials used in the construction of vehicles (cars, trains, airplanes) and other objects exposed to lightning (e.g., wind turbines). When the hull plating is made of an electrical conductor (e.g., metal alloys) it acts as a Faraday cage and upon lightning discharge the electrical charge does not cause damage to the structure. Epoxy-resin-based composites have recently been frequently used to reduce the weight of structures, but due to the insulating properties of the resin, various modifications must be applied to improve the conductivity of the composite. The methods to improve the conductivity have been categorized into three groups: modification of the matrix with conductive fillers, modification of the composite reinforcement, and addition of layers with increased electrical conductivity to the composite.

Impact of Internal Faraday Shields on RF Driven Hydrogen Discharges

At RF plasma reactors operated at high power, internal Faraday shields are required to shield dielectric vessel or windows from erosion due to isotropic heat and particle fluxes. By utilizing a flexible and diagnostically well-equipped laboratory setup, crucial effects that accompany the application of internal Faraday shields at low-pressure hydrogen (and deuterium) RF discharges are identified and quantified in this contribution. Both an inductively coupled plasma (ICP) utilizing a helical coil and a low-field helicon discharge applying a Nagoya-type III antenna at magnetic fields of up to 12 mT are investigated. Discharges are driven at 4 MHz and in the pressure range between 0.3 and 10 Pa while the impact of the Faraday shields on both the RF power transfer efficiency and spectroscopically determined bulk plasma parameters (electron density and temperature, atomic density) is investigated. Three main effects are identified and discussed: (i) due to the Faraday shield, the measured RF power transfer efficiency is globally reduced. This is mainly caused by increased power losses due to induced eddy currents within the electrostatic shield, as accompanying numerical simulations by a self-consistent fluid model demonstrate. (ii) The Faraday shield reduces the atomic hydrogen density in the plasma by one order of magnitude, as the recombination rate of atoms on the metallic (copper) surfaces of the shield is considerably higher compared to the dielectric quartz walls. (iii) The Faraday shield suppresses the transition of the low-field helicon setup to a wave heated regime at the present conditions. This is attributed to a change of boundary conditions for wave propagation, as the plasma is in direct contact with the conductive surfaces of the Faraday shield rather than being operated in a laterally fully dielectric vessel.

Spray dried hydroxyapatite-based supraparticles with uniform and controllable size and morphology

This work aims to prepare uniform spray dried hydroxyapatite-based (SD HAP-based) supraparticles with controllable morphology via micro-fluidic spray drying. Sodium polyacrylate (PAAS) and sodium chloride (NaCl) were used to prepare the precursor suspensions by regulating the inter-particle repulsive forces and electrostatic shielding effect, respectively. The particle size (D50) and zeta potential of the suspension were highly associated with the mass ratio of HAP to PAAS (mH/mP) and the NaCl concentration (CNaCl), which further had significant effect on the permeability (k) of the droplet shell formed during spray drying and ultimately the supraparticle morphology. D50 ˂ 2 µm and absolute zeta potential ˃ 20 mV, obtained when mH/mP ˂ 100 under low CNaCl, rendered ultralow k and consequently deformed supraparticles; Whereas D50 ˃ 2 µm and absolute zeta potential ˂ 20 mV, achieved by decreasing PAAS amount, i.e. mH/mP ≥ 100 or improving CNaCl to efficiently screen surface net charge of HAP, high k and spherical supraparticles were thus preferentially formed.