Lower Impedance Values Research Articles

Binder Effect on Electrochemical Performance of Silicon Anodes

Binder is a crucial component of high-capacity silicon anodes. It allows the active material to cohere to itself and surrounding materials. In the past few years, there have been divergent conclusions on the cell performance of anodes using water-based PAA vs. LiOH-PAA binder [1-3]. While there is agreement that LiOH-PAA facilitates the coating process, cell performance between these two binders is not settled.The difference in cell performance may be due to the pH value or the extra Li+ in the binder, both of which change when LiOH is added to PAA. In this work we examined these two factors separately to determine their effect on cell performance. Our hypothesis is that the extra Li+ could facilitate ion transfer and the low pH could affect current collector corrosion and silicon oxidation. NH3(aq) is used to adjust the binder slurry pH and experimental results are compared between NH3-PAA and LiOH-PAA electrodes otherwise made with the same pH value. Similarly, we compared performance of NH3-PAA anodes with different pH values.Multiple experiments were done to compare aspects of cell performance. Overall electrochemical performance was examined by cell cycling. Ionic conductivity was determined by an impedance test. Contact resistances to the current collector were measured with an apparatus developed in our lab. Silicon oxidation state was determined by XRD. Morphology of the anode can be compared by SEM.In our cycling results silicon half cells with LiOH-PAA binder had a 10% higher capacity than those with PAA binder (Fig. 1), all other factors being constant. And the LiOH-PAA film had a lower impedance value which confirms the hypothesis that extra Li+ could facilitate ion transfer. The PAA anode had a lower contact resistance to the current collector than did the LiOH-PAA anode. This result agrees with Xiong’s work [3], which claims that the corrosion of current collector when using PAA slurry could form a more rigid coating surface and thus lead to the surface cracking and lower the capacity. Other parts of this work including cycling performance and XRD are still in progress and will be reported. Hays, K.A., et al., Journal of Power Sources, 2018. 384: p. 136-144. Hu, B., et al., Journal of Power Sources, 2019. 416: p. 125-131. Xiong, J., et al., ACS Applied Materials & Interfaces, 2021. 13(24): p. 28304-28323. Figure 1

A highly stable electrode with low electrode-skin impedance for wearable brain-computer interface

To date, brain-computer interfaces (BCIs) have proved to play a key role in many medical applications, for example, the rehabilitation of stroke patients. For post-stroke rehabilitation, the BCIs require the EEG electrodes to precisely translate the brain signals of patients into intended movements of the paralyzed limb for months. However, the gold standard silver/silver-chloride electrodes cannot satisfy the requirements for long-term stability and preparation-free recording capability in wearable EEG devices, thus limiting the versatility of EEG in wearable BCI applications over time outside the rehabilitation center. Here, we design a long-term stable and low electrode-skin interfacial impedance conductive polymer-hydrogel EEG electrode that maintains a lower impedance value than gel-based electrodes for 29 days. With this technology, EEG-based long-term and wearable BCIs could be realized in the near future. To demonstrate this, our designed electrode is applied for a wireless single-channel EEG device that detects changes in alpha rhythms in eye-open/eye-close conditions. In addition, we validate that the designed electrodes could capture oscillatory rhythms in motor imagery protocols as well as low-frequency time-locked event-related potentials from healthy subjects, with similar or better performance than gel-based electrodes. Finally, we demonstrate the use of the designed electrode in online BCI-based functional electrical stimulation, which could be used for post-stroke rehabilitation.

Effects of lithium bis(oxalato)borate-derived surface coating layers on the performances of high-Ni cathodes for all-solid-state batteries

Instability of the cathode/solid electrolyte interface is a critical issue limiting the commercialization of all-solid-state batteries (ASSBs). Specifically, lithium thiophosphates (sulfide electrolytes), promising solid electrolytes, are highly reactive with oxide cathodes, leading to undesirable side reactions and electrolyte decomposition during cycling. Surface coating of oxide cathodes is an efficient approach to suppress undesirable interfacial reactions. Several ternary compounds, such as LiNbO3, LiTaO3, and Li2ZrO3, with suitable ionic conductivities have been applied as coating materials due to their appropriate stabilities against sulfide electrolytes. However, the fabrication of a coating layer containing ternary oxides requires high-temperature (over 600–800 °C) heat treatment for the homogeneous reaction of the constituent ions, which can deteriorate the performances of high-Ni cathodes. Accordingly, herein, a coating layer was synthesized using lithium bis(oxalato)borate (LiBOB) via low-temperature (below 400 °C) heat treatment. LiBOB formed thin and homogeneous coating layers on the surfaces of cathodes. LiBOB-coated cathode heat-treated at 350 °C presented higher discharge capacity, better rate capability, and lower impedance value as compared to those of the pristine cathode. Considering X-ray photoelectron spectra and energy-dispersive X-ray spectroscopy analyses of the composite cathodes, the LiBOB coating layer formed at 350 °C significantly reduced electrolyte decomposition and side reactions at the cathode/electrolyte interface, which enhanced the electrochemical performances of the LiBOB-coated cathodes. This result confirms that the LiBOB-based coating is an effective approach to improve the stability of the cathode/sulfide e Basically lectrolyte interface. Our simple and unique approach based on additives, such as LiBOB, has the potential to trigger new research on the fabrication of surface coatings at low temperatures (below 400 °C) for the cathodes of ASSBs.

EEG sensor system development consisting of solid polyvinyl alcohol–glycerol–NaCl contact gel and 3D-printed, silver-coated polylactic acid electrode for potential brain–computer interface use

The paper describes the development of a reusable electrode system for non-invasive brain–computer interface application with signal quality comparable to that of conventional wet Ag/AgCl electrodes. The innovative electrode system consists of a polyvinyl alcohol–glycerol–NaCl contact hydrogel and a 3D-printed, silver-coated polylactic acid electrode body. Advantageous features of the proposed system are the comfortable use, reusability, long shelf life, and alterable geometry. The electrical properties of freshly prepared and aged contact gels, as well as different gel/silver interfaces, were separately characterized, showing much lower impedance values than those measured at the electrode–skin interface with the complete electrode system. Acceptability limits relevant to electroencephalographic measurements, such as signal-to-noise ratio during steady-state visually evoked potential measurements and band ratio values during alpha wave detection, have proven the applicability of the system.

Supraharmonic Emissions from DC Grid Connected Wireless Power Transfer Converters

Power converters for wireless power transfer (WPT) and, in general, for electrical vehicle charging are evolving in terms of nominal power and performance, bringing along non negligible emissions in the supraharmonic range (2 kHz to 150 kHz). The large installed power and the high concentration with a relatively short separation distance can be addressed by feeding the converters through a DC grid for better dynamic response and lower impedance. The prediction of conducted emissions in real supply conditions requires carrying out measurements with low impedance values, lower than those available in line impedance stabilization networks (LISNs) for AC grids. This work proposes an approach to extrapolate converter emissions in an ideal 0 Ω condition, that together with the input impedance curve (determined by a least mean square approach) form a Norton equivalent circuit of the converter. The interaction of the converters with the DC grid and superposition of emissions can be then thoroughly evaluated by means of a general ladder grid scheme to which the Norton equivalents are connected. Such a grid model is suitable for Monte Carlo simulation aimed at assessing the degree of compensation between sources of emissions and the overall network distortion. Results using a Simulink model are provided considering emissions aggregation and compensation under random phase conditions for the following cases: close-by and separated sources (5 m and 100 m cable separation, respectively); increased number of sources studying scenarios with 3 and 10 sources; and using different resolution bandwidth values (200 Hz and 500 Hz) against a random change of the frequency of the emission components.

Fluoro-substituted polyaniline deeply incorporation with inert h-BN for interface improvement in anti-corrosion

Inert inorganic anti-corrosion fillers enjoy the advantages of stable performance, but most of them face the problems of poor compatibility and disability. Therefore, strategies about addressing the above problems need to be developed. Herein, based on interface enhancement strategy, one typical inert inorganic filler h-BN was armed with fluoro-substituted polyaniline (PFAN). To this end, diazotization reaction was utilized to introduce aniline group to h-BN, and emulsion polymerization was employed to grow the micro-size copolymer of aniline and 2-fluoroaniline. Benefitting from the above interface enhancement attempt, the compatibility of h-BN with resin was enhanced, which was explained by the chemical armed PFAN participated in the curing process of epoxy. Moreover, the disability of h-BN was also improved owed to this interface armor. Therefore, combining the fully developed barrier properties of h-BN with passivate ability of PFAN, the coating containing a small addition amount (0.9 wt%) of the composite fillers to epoxy coatings significantly improved their long-term corrosion resistance, which was confirmed by the EIS result that its low frequency impedance value was maintained above 10 10 and was about 10 3 times larger than that of pure EP coating after being immersed in 3.5 wt% NaCl solution for 120 days.

Transmission Tower Earthing Design for Lightning Condition in Malaysia’s Power Grid

The transmission tower earthing design is installed under the ground to protect nearby personnel and equipment, as well as to improve the line lightning performance. The previous tower earthing design in Malaysia’s grid system was tailored for normal power frequency fault, which are low-frequency in nature. This tower earthing design was not suitable during lightning fault, which is of higher frequency. The previous earthing design practice involves installing radial counterpoises up to 120 meters horizontally from each tower legs to get the tower footing resistance (TFR) reading of 10 Ω or less. This practice is proven to be ineffective in lowering the resistance at higher frequency i.e. lightning strike. This paper discusses a new compact earthing design that has low impedance value at low and high-frequency. The performance of this new earthing design were simulated at various soil resistivity values over a frequency range, and were compared to the performance of previous tower earthing design. The new earthing design were also installed on a number 500kV, 275kV and 132kV towers and their TFR were measured using both low and high-frequency TFR meters. The proposed concentrated earthing design was shown to have low impedance value at both low and high-frequency domain.

Controllable Electrodeposition Adjusts the Electrochromic Properties of Co and Mo Co-Modified WO3 Films

Metal ion modification is considered to be an effective way to construct metal oxides with specific physical and chemical properties. In this paper, we prepare a tungsten oxide (WO3) film co-modified by Co-ion and Mo-ion to serve as the electrochromic material through a one-step electrodeposition method. The effect of electrodeposition time on film thickness, surface morphology and electrochromic properties is systematically studied as well. The results show that, compared with pure WO3 film, the surface morphology of the tungsten oxide film modified by Co-ion and Mo-ion (WO3: Co, Mo) is significantly different. The Co and Mo co-modified film possesses a higher transmission modulation (58.5% at 600 nm) and rapid switching speed (coloring and bleaching time are 2.7 s and 5.6 s, respectively), low impedance value and excellent cycle stability. The performance enhancement is mainly attributed to the coral-like structure of the membrane, which provides a larger specific surface area, more ion adsorption sites and faster ion diffusion. Therefore, this work provides a fast and low-cost method to prepare tungsten oxide electrochromic films co-modified with cobalt and molybdenum ions. At the same time, it also provides an idea to obtain films with different electrochromic properties by adjusting the film thickness.

Chemical design of homochiral heterocyclic organic ferroelectric crystals

Single component organic ferroelectrics of spirooxazacamphorsultam derivatives, 1-SSR and 1-RRS, exhibit well-defined ferroelectricity (Ps = 2.2 μC cm-2) and piezoelectricity (d33 = 10 pC N-1) below their melting point. More importantly, they possess a low acoustic impedance value of 2.7 × 106 kg s-1 m-2, which is well-matched with body tissues.

Inrush Current Based on Fast Fourier Transform

Advances in technology have caused the use of electricity to increase rapidly. With advances in technology, this is followed by the use of increasingly efficient electrical components or equipment. This more efficient electrical equipment causes the impedance of the component to be smaller, causing a surge in current when it is turned on. This current surge, if not followed by appropriate safety precautions, will be damage other components. Each load has different waveform characteristics and current transient peaks. For this reason, it is necessary to analyze the transient condition of a load to overcome this. This paper will explain the characteristics of the inrush current of the load due to ignition. There are three loads used in this study, namely resistive, capacitive and inductive loads. Then the use of this load is simulated by giving different ignition angle values, namely 0, 60, and 90 degrees. The analysis used is the Fast Fourier Transform (FFT) method which is a derivative of the Discrete Fourier Transform. The inrush current spectrum in this simulation is simulated using Simulink MATLAB with switching system modeling using TRIAC. This inrush current simulation data collection uses a sampling frequency of 100 Khz and will be analyzed in the first of 5 cycles. For each load in this paper, the harmonic values for each ignition angle will be presented. The simulation results show that the inrush current is caused by the ignition angle value used and because of components that can deviate energy such as inductors and capacitors as well as components which at the time of starting have a low impedance value such as incandescent lamps. The simulation also shows that the use of switching components for setting the ignition angle causes an increase in the value of Total Harmonic Distortion (THD) but the peak current in the first cycle when the ignition angle is set decreases.

Low Mean Nocturnal Baseline Impedance is Associated With a Pathological Acid Exposure Time in Children.

The baseline impedance (BI) and the mean nocturnal baseline impedance (MNBI) serve as markers of mucosal integrity in patients with pathologic acid exposure time (AET). This work aims to investigate the association between the BI and MNBI with the AET in children. A retrospective study was performed in children ≤18 years old with suspicion of gastroesophageal reflux disease who underwent both endoscopy and pH-impedance monitoring (pH-MII). Esophagitis was graded according to the Los Angeles classification. The pathological AET was determined depending on the age (≥5% in patients >1 year and ≥10% in those ages ≤1 year). For the BI, 60 s measurements were taken every 4 h, and for the MNBI, 3 10 min measurements were taken between 1.00 and 3:00 am; then, they were averaged. The means of BI and MNBI were compared with each other, with the AET, and other variables. Sixty-eight patients were included, 25% of patients presented pathological AET. The mean of the MNBI was higher than BI in channels 6 (2195 vs 1997 Ω, P = 0.011) and 5 (2393 vs 2228 Ω, P = 0.013). BI and MNBI at channel 6 were lower in patients with pathological AET than in those with normal AET (1573 vs 2138 Ω, P = 0.007) and (1592 vs 2396 Ω, P = 0.004), respectively. Children with pathological AET had lower impedance values than those with normal AET. BI and MNBI measurements should be part of the routine MII-pH assessment in children.

Ultrahigh anti-corrosion performance of polymer-based coating filled with a novel micro network nanofiller

Designing fillers for high-performance anti-corrosion coatings, especially coatings suitable for harsh environments, remains a huge challenge. Herein, a novel micro network nanofiller CNTs/LDH-MoO4 (CLM) was successfully obtained by a facile in-situ growth method and employed to endow coating with excellent anti-corrosion performance. Electrochemical impedance spectroscopy (EIS) demonstrated the low frequency impedance value of the CLM coating maintained above 1011 ohm·cm2 during the 60 days of immersion in 3.5 wt.% NaCl solution. Surprisingly, the coating still exhibited superior anti-corrosion performance after being immersed for 10 days in the harsh environment where 3 MPa pure oxygen and 3.5 wt.% NaCl solution coexist.

The Effects of Potentiostat Scan Rate Variation on Impedance Value, Topography, and Morphology of the Polyaniline Thin Film

The effects of potentiostat scan rate on the impedance, topography, and morphology of the Polyaniline (PANi) thin film has observed in this study. PANi has deposited on the Quartz Crystal Microbalance (QCM) surface with various scan rates, and changes in the impedance value have observed through an impedance analyzer test. Topography Measurement System (TMS) has observed the layer topography, while the layer morphology has observed using optical microscopy and Scanning Electron Microscope (SEM). The results have shown that the best sample has a scan rate of 10 mV/s, with a low impedance value indicating the layer has rigid. The variation in scan rate can affect the impedance value, but it is not significant and does not indicate a damping effect on QCM. A homogeneous layer is deposited at a low scan rate from topography and morphological observations, while a high scan rate results in an inhomogeneous layer.

Revised Tower Earthing Design in High-Voltage Transmission Network for High-Frequency Lightning Condition

Tower earthing system for transmission grid is designed to protect the working personnel and equipment, as well as to maintain the quality of supply during fault. The existing tower earthing system for towers in TNB’s grid is catered for normal power frequency (low-frequency) fault conditions. This earthing design is found to be inapt for transient nature of lightning condition to a certain extent, which involves a high-frequency domain. The current earthing practice of installing the electrodes radially in 60 m straight horizontal lines under the ground, in order to achieve the specified impedance value of less than 10 ?, was deemed ineffective in reducing the high-frequency impedance. This paper introduces a new earthing design that produces low impedance value at the high-frequency domain, without compromising the performance of low-frequency impedance. The performance of this new earthing design, as well as the existing design, are simulated for various soil resistivity values at varying frequency. The proposed concentrated earthing design is found to possess low tower footing resistance (TFR) value at both low and high-frequency. A good earthing design should have a fine balance between compact and radial electrodes under the ground.

Fabrication of nanomolded Nafion thin films with tunable mechanical and electrical properties using thermal evaporation-induced capillary force lithography.

In this paper, we report a simple and facile method to fabricate nanomolded Nafion thin films with tunable mechanical, and electrical properties. To achieve this, we combine a novel thermal evaporation-induced capillary force lithography method with swelling process to obtain enhanced pattern fidelity in nanomolded Nafion films. We demonstrate that structural fidelity and mechanical properties of patterned Nafion thin films can be modulated by changing fabrication parameters such as swelling time, Nafion polymer concentration, and curing temperature. Interestingly, we also find that impedance properties of nanomolded Nafion thin films are associated with the Nafion polymer concentration and curing temperature. In particular, 20% Nafion thin films exhibit greater impedance stability and lower impedance values than 5% Nafion thin films at lower frequencies. Moreover, curing temperature-specific impedance changes are observed. These results suggest that capillary lithography can be used to fabricate Nafion nanostructures with high pattern fidelity capable of modifying mechanical and electrical properties of Nafion thin films.

Reservoir Distribution Analysis with Seismic Colored Inversion in Fluvial Deposition Environment West Natuna Basin

West Natuna Basin is a fluvial deposition environment with thin-bed sand reservoir overlapping with shale and shaly sand. Inversion is applied using Seismic Colored Inversion which considered to provide with robust result to identify geological features such as sand channels’ continuity with low-acoustic impedance value alongside zone of interest. Seismic Colored Inversion can be made by inverting seismic data into Acoustic Impedance value which can be obtained by deriving data from well, as control, then utilized it to change the seismic data volume to Acoustic Impedance volume. By performing a lateral slicing along the target horizons, the distribution of sand channels can be identified. Therefore, the promising reservoir zone with low Acoustic Impedance value and the non-reservoir zone can be clearly distinguished. Slicing was performed in A1 horizon, showing low AI sand channels ranging from 12.000 up to 15.500 ((ft/s)*(g/cc)) spreading at the center of the map through the East. Slicing in B2 horizon, showing what appears to be sand channels with low AI value ranging from 16.000 up to 17.800 ((ft/s)*(g/cc)) spreading at the center of the map between the U1 and U3 well, and appears at the Northeast of the map.

Influence of chloride and pH on the pitting mechanism of Zn‐Ni alloy coating in sodium chloride solutions

AbstractThis paper presents the pitting corrosion behaviour of Zn‐Ni alloy coatings in NaCl solutions with different chloride concentrations and pH. The pitting‐behaviour investigation is done using an optical microscope, potentiodynamic polarization (Tafel slopes), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) integrated with energy dispersive spectroscopy (EDS). The design of the experiment with three‐level fractional factorial design (FFD) is used to analyze the behaviour of pitting corrosion. The pitting behaviour in acidic solution with low chloride concentration was found to be significantly different from that in the neutral solution with high chloride concentration. Electrochemical analysis indicates that the corrosion behaviour of samples immersed at 0.35 moL/L NaCl and pH 3.0 at different exposure times have low impedance values compared to the 0.35 moL/L NaCl and pH 7.0 samples. SEM images show that the pH and chloride concentration in the electrolyte has a significant influence on the pitting morphology. Exclusive large pit morphology in an acidic solution (pH 3.0) with low chloride concentration (0.35 moL/L) was also observed. This provides new insight into pitting behaviour on a coated material. The study will serve a valuable tool toward designing or selecting metal coatings for marine or corrosive environments.

Corrosion protection performance of epoxy coating containing alumina/PANI nanoparticles doped with cerium nitrate inhibitor on Al-2024 substrates

Alumina/polyaniline hybrid nanoparticles doped with cerium nitrate corrosion inhibitor was synthesized via a chemical polymerization method. The morphology and structure of the synthesized nanoparticles were investigated by field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and X-Ray diffraction (XRD) techniques. Incorporation of alumina/polyaniline nanocomposite particles doped with cerium nitrate into epoxy coating on aluminum alloy 2024-T3 resulted in a protective system with superior corrosion protection performance confirmed by potentiodynamic scanning method (PDS) and electrochemical impedance spectroscopy (EIS). The corrosion current density of the nanocomposite coating was (7.35 ± 0.22)×10−9 A/cm2, which was reduced by two orders of magnitude compared with that of the control epoxy sample. Moreover, the embedding of cerium nitrate doped alumina/polyaniline nanoparticles into epoxy coating provides active protection against corrosion. The low frequency impedance values of the scratched area of this coating after 6 days immersion was three orders of magnitude higher than that of the control sample.

Ar plasma-assisted P-doped Ni3S2 with S vacancies for efficient electrocatalytic water splitting.

Doping engineering is considered an effective way to improve the electrocatalytic water splitting performance of catalysts. In this paper, P-doped Ni3S2/NF was prepared by Ar plasma-assisted chemical vapor deposition, where the P dopant was efficiently introduced into Ni3S2/NF under the assistance of Ar plasma. Meanwhile, numerous vacancies were generated due to plasma bombardment. In the doping process, the P dopants replace the S vacancies, which contributes to the strong bonding between the P dopants and Ni3S2. Due to the synergistic effect of the P dopants and S vacancies, the Sv-Ni3S2-xPx-4 catalyst has low HER and OER overpotentials of 89 mV and 216 mV at 10 mA cm-2, with a lower impedance value and good stability. The present work shows a facile route to introduce dopants and vacancies into catalyst materials for adding active sites, eventually improving their electrocatalytic performance.

The Active Electrode in the Living Brain: The Response of the Brain Parenchyma to Chronically Implanted Deep Brain Stimulation Electrodes.

Deep brain stimulation is an established symptomatic surgical therapy for Parkinson disease, essential tremor, and a number of other movement and neuropsychiatric disorders. The well-established foreign body response around implanted electrodes is marked by gliosis, neuroinflammation, and neurodegeneration. However, how this response changes with the application of chronic stimulation is less well-understood. To integrate the most recent evidence from basic science, patient, and postmortem studies on the effect of such an "active" electrode on the parenchyma of the living brain. A thorough and in-part systematic literature review identified 49 papers. Increased electrode-tissue impedance is consistently observed in the weeks following electrode implantation, stabilizing at approximately 3 to 6 mo. Lower impedance values are observed around stimulated implanted electrodes when compared with unstimulated electrodes. A temporary reduction in impedance has also been observed in response to stimulation in nonhuman primates. Postmortem studies from patients confirm the presence of a fibrous sheath, astrocytosis, neuronal loss, and neuroinflammation in the immediate vicinity of the electrode. When comparing stimulated and unstimulated electrodes directly, there is some evidence across animal and patient studies of altered neurodegeneration and neuroinflammation around stimulated electrodes. Establishing how stimulation influences the electrical and histological properties of the surrounding tissue is critical in understanding how these factors contribute to DBS efficacy, and in controlling symptoms and side effects. Understanding these complex issues will aid in the development of future neuromodulation systems that are optimized for the tissue environment and required stimulation protocols.