Resistive Surface Layer Research Articles

Development of a 3-Electrode Setup for the Operando Detection of Parasitic Side Reactions: Exemplified at the Quantification of Released Oxygen

The most considerable push to higher energy density Li-ion batteries (LiBs) has been achieved by incremental improvements of the positive electrode cathode active materials (CAM).1 One approach has been to increase the nickel content of layered transition metal oxide CAMs like lithium nickel cobalt aluminum oxide (NCA; LiNixCoyAlzO2, with x+y+z=1) to above 80%, which has already been achieved on a commercial level. While this increase is accommodated by a higher achievable discharge capacity at a given upper cut-off potential, it also reduces the structural stability of the material at high degrees of delithiation (i.e. at high state-of-charge (SOC)).2,3 The structural instability of the CAM is associated with a release of lattice oxygen at high SOC, starting at approximately 80% SOC.2,3 The release of reactive oxygen species is reported to cause a cascade of degradation mechanisms resulting in capacity fade. During this process, the near-surface region of layered transition metal oxide particles is converted into an electrochemically inactive rock-salt phase, which results in the formation of a resistive surface layer.4 Furthermore, the released oxygen can stimulate the chemical oxidation of the typically employed electrolyte solvents, such as ethylene carbonate (EC), resulting in the formation of CO, CO2, and H2O, which in turn hydrolyzes the electrolyte salt.2,5 Consequently, the detection and quantification of released oxygen for different CAMs and cycling conditions is of high interest. Gas quantification methods such as differential electrochemical mass spectrometry (DEMS) and on-line electrochemical mass spectrometry (OEMS) are powerful tools for the qualitative and quantitative measurement of gaseous species such as O2 and CO2.2,6 However, such methods require an expensive mass spectrometer setup and a sophisticated interface between the LiB cell hardware and the mass spectrometer.Thus, in this study, we will present a simplified method that can detect and quantify released oxygen. The method is based on a setup consisting of a dual working electrode (WE) configuration, namely a primary WE with an NCA CAM (LiNi0.80Co0.15Al0.05O2, from BASF TODA Battery Materials LLC, Japan) and an auxiliary WE with only carbon (Vulcan-type carbon, XC-72, Tanaka, Japan), both being coated with a ; a lithium iron phosphate (LFP) electrode coated on aluminum serves as counter electrode (CE). The latter is delithiated to a degree of 90% and capacitively oversized, allowing the NCA working electrode to be cycled against a constant potential (with the LFP potential being at ~3.43 V vs. Li+/Li).8 While charging the NCA working electrode within the desired potential window, the carbon electrode is polarized to a constant potential of 1.21 V vs. the LFP counter electrode corresponding to ~2.20 V vs. Li+/Li. Since oxygen is reduced at that potential, a reductive current is detected once lattice oxygen is being evolved.9 By the precise knowledge of the number of electrons involved in the reduction of oxygen at the carbon electrode, we are able to convert the reductive current into an amount of released oxygen (e.g., in units of moles of oxygen per gram of cathode active material).We apply the developed cell setup to study the oxygen release characteristics of the NCA when being charged to 5.0 V vs. Li+/Li at 0.1 C and 25 °C, and compare these data to the gassing profile analyzed via OEMS. As will be shown, there is a good agreement between integrated and converted reductive current and the amount of detected O2 in the OEMS.

Water-Resistance-Based S-Scheme Heterojunction for Deep Mineralization of Toluene.

Deep mineralization of low concentration toluene (C7 H8 ) is one of the most significant but challenging reactions in photocatalysis. It is generally assumed that hydroxyl radicals (⋅OH) as the main reactive species contribute to the enhanced photoactivity, however, it remains ambiguous at this stage. Herein, a S-scheme ZnSn(OH)6 -based heterojunction with AlOOH as water resistant surface layer is in situ designed for tuning the free radical species and achieving deep mineralization of C7 H8 . By employing a combination of in situ DRIFTS and materials characterization techniques, we discover thatthe dominant intermediates such as benzaldehyde and benzoic acid instead of toxic phenols are formed under the action of holes (h+ ) and superoxide radicals (⋅O2 - ). These dominant intermediates turn out to greatly decrease the ring-opening reaction barrier. This study offers new possibilities for rationally tailoring the active species and thus directionally producing dominant intermediates via designing water resistant surface layer.

Water‐Resistance‐Based S‐Scheme Heterojunction for Deep Mineralization of Toluene

AbstractDeep mineralization of low concentration toluene (C7H8) is one of the most significant but challenging reactions in photocatalysis. It is generally assumed that hydroxyl radicals (⋅OH) as the main reactive species contribute to the enhanced photoactivity, however, it remains ambiguous at this stage. Herein, a S‐scheme ZnSn(OH)6‐based heterojunction with AlOOH as water resistant surface layer is in situ designed for tuning the free radical species and achieving deep mineralization of C7H8. By employing a combination of in situ DRIFTS and materials characterization techniques, we discover that the dominant intermediates such as benzaldehyde and benzoic acid instead of toxic phenols are formed under the action of holes (h+) and superoxide radicals (⋅O2−). These dominant intermediates turn out to greatly decrease the ring‐opening reaction barrier. This study offers new possibilities for rationally tailoring the active species and thus directionally producing dominant intermediates via designing water resistant surface layer.

Tuning enhanced dielectric properties of (Sc3+–Ta5+) substituted TiO2 via insulating surface layers

In this study, we achieved significantly enhanced giant dielectric properties (EG-DPs) in Sc3+–Ta5+ co-doped rutile-TiO2 (STTO) ceramics with a low loss tangent (tanδ ≈ 0.05) and high dielectric permittivity (ε′ ≈ 2.4 × 104 at 1 kHz). We focused on investigating the influence of insulating surface layers on the nonlinear electrical properties and the giant dielectric response. Our experimental observations revealed that these properties are not directly correlated with the grain size of the ceramics. Furthermore, first-principles calculations indicated the preferred formation of complex defects, specifically 2Ta diamond and 2ScVo triangular-shaped complexes, within the rutile structure of STTO; however, these too showed no correlation. Consequently, the non-Ohmic properties and EG-DPs of STTO ceramics cannot be predominantly attributed to the grain boundary barrier layer capacitor model or to electron-pinned defect-dipole effects. We also found that the semiconducting grains in STTO ceramics primarily arise from Ta5+, while Sc3+ plays a crucial role in forming a highly resistive outer surface layer. Notably, a significant impact of grain boundary resistance on the nonlinear electrical properties was observed only at lower co-dopant concentrations in STTO ceramics (1 at%). The combination of low tanδ values and high ε′ in these ceramics is primarily associated with a highly resistive, thin outer-surface layer, which substantially influences their non-Ohmic characteristics.

Activating Selenium Cathode Chemistry for Aqueous Zinc-Ion Batteries.

Aqueous rechargeable zinc-ion batteries (ARZIBs) are a promising next-generation energy storage device by virtue of the superior safety and low cost of both the aqueous electrolyte and zinc metal anode. However, their development has been hindered by the lack of suitable cathodes with high volumetric capacity that can provide both lightweight and compact size. Herein we report a novel cathode chemistry based on amorphous Se doped with transition metal Ru that mitigates the resistive surface layer produced by the side reactions between the Se cathode and aqueous electrolyte. This improvement can permit high volumetric capacity in this system. Distinct from conventional conversion mechanisms between Se and ZnSe in Se||Zn cells, this strategy realizes synchronous proton and Zn2+ intercalation/deintercalation in the Ru-doped amorphous Se||Zn half cells. Moreover, an unanticipated Zn2+ deposition/stripping process in this system further contributes to the superior electrochemical performance of this new cathode chemistry. Consequently, the Ru-doped amorphous Se||Zn half cells are found to deliver a record-high capacity of 721 mAh g-1 /3472 mAh cm-3 , and superior cycling stability of over 800 cycles with only 0.015% capacity decay per cycle. This reported work opens the door for new chemistries that can further improve the gravimetric and volumetric capacity of ARZIBs. This article is protected by copyright. All rights reserved.

Effects of Porous Transport Layer Coating Inhomogeneities on PEM Water Electrolyzer

The porous transport layer (PTL) is a critical component of polymer electrolyte membrane (PEM) water electrolyzers, transporting water to the anode catalyst layer, conducting electrons, and removing the produced oxygen. Ti materials such as felts, mesh, and sintered powders are commonly used as PTLs at the anode due to the good corrosion resistance and conductivity of Ti. However, Ti forms an electrically resistive oxide surface layer that has detrimental effects on the performance and durability of PEM electrolyzer cells. In order to permit the use of Ti PTLs in PEM electrolyzers, platinum group metals (PGMs) such as Pt and Ir can be used as a conductive, protective layer [1-3]. However, use of PGM coatings adds to the cost of PEM electrolyzers, and it is likely that future systems will use thinner coatings to minimize cost. To implement the PEM water electrolysis on a larger scale, it is essential to minimize the cost of mass-manufactured cell components while ensuring that inhomogeneities do not adversely affect the performance and durability of the cell and ultimately the stack. Improved understanding of impact of inhomogeneities on cell performance and durability is key to enabling this goal.This study investigates the impacts of PTL coating inhomogeneities on the performance of PEM water electrolyzers. Coating inhomogeneities of various geometries were artificially made on Ti felt PTLs to investigate the effects on the cell performance and understand fabrication tolerances. In addition, a model is developed to analyze the impacts of coating geometry on the surface current density distribution and local electric potential of the cell. Reference Kang, Z., et al., Effects of interfacial contact under different operating conditions in proton exchange membrane water electrolysis. 2022. 429: p. 140942.Liu, C., et al., Constructing a Multifunctional Interface between Membrane and Porous Transport Layer for Water Electrolyzers. 2021. 13(14): p. 16182-16196.Liu, C., et al., Exploring the Interface of Skin ‐Layered Titanium Fibers for Electrochemical Water Splitting. Advanced Energy Materials, 2021. 11(8): p. 2002926.

Structure and Electric Properties of Anodized Aluminum with PEDOT:PSS Conductive Polymer Cathode

Aluminum solid electrolytic capacitors using a conductive polymer as a cathode material has the advantages of low equivalent series resistance (ESR) and high thermal stability compared to aluminum electrolytic capacitors using liquid electrolytes. A disadvantage of aluminum solid electrolytic capacitors with a conductive polymer is the low breakdown voltages, limiting the operating voltage of the capacitors to ∼100 V or less. In this study, for a possible future increment of the withstand voltages of solid electrolytic capacitors, PEDOT:PSS-coated aluminum with an amorphous or crystalline alumina layer formed at 500 V has been characterized using SEM, STEM/EDS, and conductive AFM to understand the distribution of PEDOT:PSS conductive polymer and its influence on the electric properties. The crystalline alumina layer, developed beneath a porous hydrated alumina layer, contains many voids, which increase the leakage current compared to the void-less amorphous alumina layer. However, the crystalline alumina layer with PEDOT:PSS exhibits a higher breakdown voltage than the amorphous one. The limited incorporation of PEDOT:PSS into the inner part of the porous hydrated alumina layer may introduce a resistive surface layer, possibly contributing to the increased dielectric breakdown.

Inverse Thermal Analysis as a Tool for Optimizing Concentrated Solar Energy Elaboration of Wear Resistant Surface Layers

Concentrated Solar Energy (CSE) processing is considered a promising renewable energy source technique for elaborating thick, wear-resistant claddings onto metallic surfaces of large dimensions that are expected to operate in heavy duty applications, such as excavator shovels, mineral crushers, etc. However, the prediction of surface processing effects on the microstructure and the properties of the main construction base metal are of crucial importance, as they are commonly required in all surface modification techniques. Thus, the present study is focused on the inverse thermal analysis and parametric modeling of heat deposition associated with CSE surface processing of metals. In this preliminary attempt, experimental findings that concern the elaboration of TiC- and chromium carbide-reinforced clads onto common steel base metals were used to quantify the evaluation of the temperature histories within the volume of workpieces undergoing solar heating, where direct temperature measurements contain uncertainties and/or are not even possible. Results of prototype inverse thermal analyses of heat transfer in processed layer-substrate systems are presented, demonstrating the general aspects of a parametric model for thermal analysis and simulation.

Design of an optically transparent EMW structure with broadband‐absorbing property

AbstractIn this paper, an optically transparent electromagnetic window structure based on frequency selective absorber (FSA) technique is proposed with low‐pass and high broadband absorbing property. The FSA consists of two resistive frequency selective surface layers and a low‐passband layer, which are all designed using square ring structures. To make the whole design transparent, the traditional metal copper and resistors are replaced by indium tin oxide and the dielectric substrate by polyethylene terephthalate. The top and middle layers act as absorbing layers to generate broad absorption bands at high frequencies, while the bottom layer is used to generate low‐pass transmission bands. The simulation results show that the insertion loss is less than 3 dB below 3.6 GHz, while the absorption bandwidth covers 6–18 GHz with an angular stability reaches 45°.

Role of surface carbon nanolayer on the activation of flash sintering in tungsten carbide

Flash sintering has been recently successfully activated also in conductive ceramics like tungsten carbide (WC). The present work aims at understanding how the WC particles surface chemistry can influence the electrical properties of the material and play a fundamental role in the flash sintering phenomenon. An electrical contact resistance (ECR) model was developed to understand the role of resistive surface layers on the electrical behaviour of WC green compacts under different applied pressures during the initial stages of the processes. It is established that the large resistivity measured on green compacts can be attributed to the sole presence of an ultrathin carbon layer on the particles' surface. A carbon nanolayer with a thickness of about 1–2 nm, as detected by XPS and TEM analyses, is found to be responsible for the high resistance reached at the particles' contact points while evolving during the flash event. Flash sintering conditions can be achieved during the electrical resistance flash sintering (ERFS) process in WC nanoparticles covered by such carbon layer and independently of the presence of W oxides.

Magnetotelluric imaging of the shallow-seated magma reservoir beneath the Karadağ stratovolcano, Central Anatolia, Turkey

The central Anatolian Volcanic Province encompasses many volcanoes elongated in a northeast-southwest direction. Karadağ is one of the dormant Quaternary stratovolcanoes of the region at the southern end of the province. We acquired broadband magnetotelluric (MT) data in the period range 0.0001–251 s at 124 locations to obtain a three-dimensional electrical resistivity model to identify the associated magmatic-hydrothermal system beneath the Karadağ stratovolcano. The resistivity model provides evidence for low resistivity anomalies that include (1) a near-surface localised low resistivity (~ 20 Ωm) zone situated directly beneath the crater centre that is interpreted to be lacustrine sediments of an extinct crater lake, (2) a shallow low resistivity (~ 10 Ωm) zone of probable hydrothermal alteration in the eastern part of the stratovolcano and (3) a deep and large zone of low resistivity (<10 Ωm) attributed to a shallow-seated magma reservoir at a depth of 3 to 7 km beneath the volcanic edifice. A few hundred meters thick resistive surface layer corresponds to the Karadağ adakitic volcanics (i.e., andesites and dacites), and a resistive basement representing Precambrian to Mesozoic high- and medium-grade metamorphic rocks on the flanks is observed in the resistivity model.

Novel Method for Monitoring the Electrochemical Capacitance by In Situ Impedance Spectroscopy as Indicator for Particle Cracking of Nickel-Rich NCMs: Part II. Effect of Oxygen Release Dependent on Particle Morphology

Nickel-rich NCMs (LiMO2, with M = Ni, Co, and Mn) are increasingly commercialized as cathode active materials for lithium-ion batteries due to their high specific capacity. However, the available capacity is limited due to their structural instability at high state of charge, causing the formation of a resistive surface layer upon release of lattice oxygen, observed at different upper cutoff potentials depending on the NCM composition. To understand the impact of this instability, the correlation of oxygen release, capacity fading, and particle cracking was investigated as a function of state of charge for three nickel-rich NCMs, differing either in composition (i.e., in transition metal ratio) or in morphology (i.e., in primary crystallite size). First, the onset of the release of lattice oxygen was identified by on-line electrochemical mass spectrometry (OEMS). In electrochemical cycling experiments, the NCM capacitance was tracked in situ by impedance spectroscopy (EIS) using a micro-reference electrode while the upper cutoff potential was increased every third cycle stepwise from 3.9 V to 5.0 V. Hereby, the effect of the degree of delithiation on the discharge capacity and on the particle integrity (tracked via its surface area) was examined, both for poly- and single-crystalline NCMs.

Oxalic Acid as a Cathode Additive Increasing Rate Capability of Ni-Rich Layered Cathode Materials

Ni-rich layered cathode is known as the main limit for the fast charge of Li-ion batteries. With a focus on Ni-rich LiNi0.80Co0.10Mn0.10O2 (NCM811) cathode, two strategies have been attempted to improve the rate capability of Li-ion cells, one by breaking down the spherical secondary structure to increase the material’s surface area and the other by reconstructing the native surface layer to reduce interfacial resistance between the active material and the electrolyte. In the milling process, it was found that conducting carbon buffers NCM811 particles from breaking down, and that a decrease in the content of carbon makes it possible to break down the spherical secondary structure. Because NCM811 particles are natively covered by a dense and resistive surface layer consisting mainly of alkaline residual lithium compounds (RLCs), adding an appropriate amount of H2C2O4 into the slurry is shown to dramatically reduce interfacial resistance between the cathode and electrolyte. This is because H2C2O4 reacts with RLCs to reconstruct the texture of the dense native surface layer, which allows the liquid electrolyte to permeate and wet the active material and hence reduces the electrolyte-electrode interfacial resistance. This simple process provides an operation-viable and cost-effective strategy for improving the rate capability of Li-ion batteries.

Subsurface Structure around Mas Crater of Papandayan Volcano based on Magnetotelluric and Geomagnetic Data

Papandayan is a hydrothermally active volcano in Indonesia. We revealed the subsurface structure around the Mas Crater area of Papandayan based on the magnetotelluric (MT) and geomagnetic (GM) method. For the MT method, 14 sounding stations were deployed and two of them are located close to the active fumaroles. We estimated the MT response functions using a remote reference and then modeled the data with the aid of a 1-D robust inversion. The resistivity structure can generally be divided into three layers, namely a thin resistive surface layer, a middle conductive layer, and a more resistive basement. We interpreted the middle layer to be the hydrothermal zone or clay mineral. For the GM method, we measured the total intensity at 19 data points. The IGRF and diurnal variation were subtracted from the raw data. We then obtained the 2-D magnetic susceptibility model of magnetic field anomaly using an Occam inversion. The model shows a significantly low susceptibility structure beneath the fumaroles which might correlate with thermally demagnetized rocks.

Многофазные покрытия Cu-Ti, нанесенные плазменным вакуумно-дуговым напылением на Cu-Be сплав С17200

Introduction. Deposition of hard intermetallic coatings is an efficient technology to improve operating characteristics of Cu-Be alloys. PVD of coatings is widely used for surface engineering of constructive materials, deposition of wear and corrosion resistant surface layers. Multiphase and multicomponent coatings are considered as the most efficient hard coatings for surface engineering. In this research, Ti-Cu coatings are deposited by a vacuum-arc plasma-assisted method on hardened BrB2 bronze (alloy C17200) at a temperature of 320 – 330 oC. Processing resulted in ageing of Cu-Be alloy and surface hardening of material. The aim of the research is to analyze the microstructure, phase composition, and tribological properties of Cu-Be alloys modified with plasma-activated PVD coatings based on titanium, with the subsequent development of an effective technology for surface engineering and improvement of the mechanical properties of Cu-Be alloys. Results and discussion. Plasma-assisted PVD of Cu-Ti coatings on the surface of tempered C17200 alloy at 320 – 330 oC resulted in formation of multiphase coatings, consisting of Cu, Ti, CuTi and CuTi2 components. X-ray analysis revealed development of ageing process in Cu-Be alloy which resulted in formation of CuBe inclusions. Wear resistance of modified blocks is investigated. The main mechanism of modified blocks wearing is cracking of the coating with further formation of fine debris of base Cu-Be material. Wear debris is significantly smaller then debris of С17200 alloy without coating. Surface microhardness of blocks processed at 320 –330 oC is comparatively high (540 HV0.02 - 530 HV0.02). Wear resistance of blocks subjected to surface engineering is comparatively low probably because of small thickness of the coating (&lt; 8 µm) and insufficient hardness of matrix material.

Corrosion Resistant Cold Sprayed Cladding for Molten Salt Reactors

The bimetallic structure concept consisting of a corrosion resistant surface layer joined on top of an ASME code-approved substrate becomes a promising solution to address the corrosion issue of ASME substrate materials in molten salt environment. Specifically, refractory materials such as molybdenum, tungsten, and alloys containing them are found to be most resistant in molten salt environment and hence they have great potential to be used as the protective salt-facing surface layer. Due to the well-recognized difficulties of welding/3D-printing refractory materials (i.e., oxidation, brittle phase formation, cracking, etc.), cold spray, a deposition technology that minimizes material heating, avoids undesired thermal effects and maintains dimension stability, is an ideal approach for fabricating the bimetallic components. A corrosion resistant cladding material that is also amenable to cold spray process is desired and has been developed. Promising cladding structure has been designed, and tested by both molten salt corrosion and cold spray trials for down-selection. Prototyping for clad adhesion test will also be conducted as proof-of-concept validation. This program is sponsored by DOE Office of Nuclear Energy.

A Comparative Study of Structural Changes during Long-Term Cycling of NCM-811 at Ambient and Elevated Temperatures

Ni-rich layered oxides, like NCM-811 (Li1+δ[Ni0.8Co0.1Mn0.1]1-δO2), are promising cathode active materials for lithium-ion-batteries used in applications such as portable devices and battery electric vehicles. An increased Ni-content typically allows for a higher reversible lithium usage at a given cell potential, thereby improving the specific capacity. However, pronounced capacity fading, especially at high voltages and elevated temperatures, still leads to a limited cycle life.1 The underlying degradation mechanisms and whether they are due to detrimental reactions in the bulk or at the surface, are still controversially discussed in the literature.2,3 We will show a comparison of two studies investigating the capacity fading of NCM-811/graphite full-cells over several hundreds of cycles at ambient and elevated temperatures. In order to focus on the NCM-811 material, we excluded Li loss at the anode by pre-lithiating the graphite anode. The first study was conducted in-situ with two cells cycled at ambient temperature (≈22°C) over 1000 cycles,4 while in the follow-up study a number of pouch-cells were analyzed after cycling at 45°C for up to 700 cycles. As shown in Figure 1a, all cells were cycled at a C-rate of C/2 in a potential window between 3.0 and 4.5 V vs. a Li reference electrode at both 22°C (black line in Fig. 1a) and at 45°C (blue line in Fig. 1a), with two additional C/10 cycles every 50 cycles in case of the 45°C study (blue dots in Fig. 1a). One cell was disassembled every 150 cycles to conduct ex-situ experiments, such as X-ray powder diffraction (XPD) and impedance spectroscopy. A quantitative correlation between the NCM-811 lattice parameters and the Li amount, xLi, allows for monitoring the different contributions to the capacity loss by XPD.4 In the 22°C study, it was shown that the continuous growth of a resistive surface around the NCM-811 primary particles results in (i) an irreversible capacity loss due to the material lost for its formation, and (ii) in a significant impedance growth. The former is compared for both studies according to our XPD analysis in Figure 1b, showing a clear difference in the progression and in the absolute values, suggesting a more detrimental process to kick-in after ≈550 cycles at 45°C. In contrast to the time consuming XPD analysis, the material loss was also quantified by slow C/50 cycling, a rate which is slow enough to not lead to overpotential induced capacity losses due to the gradual resistance build-up over cycling. Hence, this approach could be verified to be a far more practical method to determine the material loss during cycle-life tests. In addition, the bulk material stability in terms of the Li-Ni mixing was analyzed by Rietveld refinement of the XPD data. In contrast to the study conducted at ambient temperature, where the extent of Ni disorder was observed to remain at an essentially constant value over 1000 cycles, it was found to clearly increase when cycling the cells at 45°C over 700 cycles (see Figure 1c).In conclusion, we can state that at both temperatures a resistive surface layer is formed, suggesting that future research should focus on stabilizing the surface of Ni-rich materials. In addition to this surface process, the bulk stability of NCM-811 is altered at elevated temperatures, which is manifesting itself in an increasing Ni disorder.Figure 1:Comparison of data obtained from NCM-811/graphite pouch-cells cycled at ≈22°C (black symbols) and at 45°C (blue symbols) between 3.0 and 4.5 V vs. Li+/Li (controlled vs. Li reference electrode) at the indicated C-rates. (a) Discharge capacity of two exemplary cells, (b) relative material loss of the NCM-811 calculated from XPD analysis, (c) Ni disorder determined via XPD of harvested electrodes after cycling to the indicated cycle number at 45°C (error from calculating the average of two independent measurements).Acknowledgement:This work is financially supported by the BASF SE Network on Electrochemistry and Battery Research.

Local electronic transport across probe/ionic conductor interface in scanning probe microscopy

Charge carrier transport through the probe-sample junction can have substantial consequences for outcomes of electrical and electromechanical atomic-force-microscopy (AFM) measurements. For understanding physical processes under the probe, we carried out conductive-AFM (C-AFM) measurements of local current-voltage (I-V) curves as well as their derivatives on samples of a mixed ionic-electronic conductor Li1-xMn2O4 and developed an analytical framework for the data analysis. The implemented approach discriminates between contributions the highly resistive sample surface layer and the bulk with the account of ion redistribution in the field of the probe. It was found that, with increasing probe voltage, the conductance mechanism in the surface layer transforms from Pool-Frenkel to space-charge-limited current. The surface layer significantly alters the ion dynamics in the sample bulk under the probe, which leads, in particular, to a decrease of the effective electromechanical AFM signal associated with the ionic motion in the sample. The framework can be applied for the analysis of electronic transport mechanisms across the probe/sample interface as well as to uncover the role of the charge transport in the electric field distribution, mechanical, and other responses in AFM measurements of a broad spectrum of conducting materials.

The Synthesis of Soil Resistivity and EMF of underground Cable combined with 3-D Electromagnetic Field Study in Analyzing the Grounding Touch

The earthing analysis is proposed in this paper. The effects of 3-D electromagnetic field and the influences of stray currentare considered in the text simultaneously. The activity in the high-voltage environment is risky of being injured by electricshock. The safety of personnel in and around electric power the installations has been a prime concern. Specially, the safety isgenerally in terms of the allowable touch and step voltages. These voltages are related to the earthing resistance of human foot.I ofn order to increase the safety of personnel, a high resistivity surface layer of gravel is normally existed in the substationswitchyards or other high voltage areas. The thickness of this layer will affect the calculation of the earthing resistance ofhuman foot. Thus, the effect of soil resistivity will be considered in this paper. Among them, the electromagnetic field andhumidity factors are also considered in this paper. As a result, the surface layer of gravel can be used to reduce the earthingresistance of human foot. The equivalent model of human foot was modeled by the circular plate conductor in the past. Whichconsider the beauty of the environment, most of the transmission lines are in the surface, so the transmission line generated bythe discrete current will affect the earthing resistance estimation, thus the proposed paper will consider the composition of thespecial function which is the mathematical calculus popularized by the basic theorem of calculus. On the other hand, the dampingredients, temperatures, and soil resistivity on the surface will also be considered in this paper. This paper research into theproposed method for estimating the earthing resistance of human foot and proposes an equivalent model for calculating thegrounding resistance of human foot. The comparisons of the method are also shown in this paper.

Boosting High-Performance in Lithium-Sulfur Batteries via Dilute Electrolyte.

Polysulfide shuttle effects, active material losses, formation of resistive surface layers, and continuous electrolyte consumption create a major barrier for the lightweight and low-cost lithium-sulfur (Li-S) battery adoption. Tuning electrolyte composition by using additives and most importantly by substantially increasing electrolyte molarity was previously shown to be one of the most effective strategies. Contrarily, little attention has been paid to dilute and super-diluted LiTFSI/DME/DOL/LiNO3 based-electrolytes, which have been thought to aggravate the polysulfide dissolution and shuttle effects. Here we challenge this conventional wisdom and demonstrate outstanding capabilities of a dilute (0.1 mol L-1 of LiTFSI in DME/DOL with 1 wt. % LiNO3) electrolyte to enable better electrode wetting, greatly improved high-rate capability, and stable cycle performance for high sulfur loading cathodes and low electrolyte/sulfur ratio in Li-S cells. Overall, the presented study shines light on the extraordinary ability of such electrolyte systems to suppress short-chain polysulfide dissolution and polysulfide shuttle effects.