Ac Impedance Spectroscopy Technique Research Articles

Inkjet-Printed LSM-YSZ Thin Films for Enhanced Oxygen Electrodes in Solid Oxide Fuel Cells.

In the present work, symmetrical oxide ion conducting solid oxide single cells with inkjet-printed composite LSM-YSZ electrodes, onto commercially available YSZ dense substrates using GDC as buffer interlayer, were fabricated and characterized. Stable inkjet-printable LSM-YSZ nanoparticle inks were developed based on water solvent, after processing with high intensity ball milling. The deposition of LSM-YSZ electrodes was performed by inkjet printing, as well as a conventional additive manufacturing technique, screen printing, in order to compare the electrochemical performance of the produced cells for the reversible charge transfer reaction (O2 + 4 e- ↔ 2 O2-). The physicochemical properties of the LSM-YSZ nanoparticle ink was investigated to determine ink printability. The electrochemical performance of fabricated inkjet-printed and screen printed symmetrical cells (LSM-YSZ | GDC | YSZ | GDC | LSM-YSZ) exposed under a synthetic air atmosphere was evaluated in a single chamber cell reactor, employing the AC impedance spectroscopy and linear scan voltammetry techniques, at the temperature range of 700-850 °C. The inkjet-printed electrodes exhibited highly homogeneous and porous morphologies with the corresponding cell achieving current densities almost five times higher, up to 1 A/cm2 at 2 V cell potential and 850 °C, than those of the equivalent screen-printed one. To the best of our knowledge, this is the first successful implementation of water-based inks of LSM-YSZ electrodes in the fabrication of inkjet-printed solid oxide cells.

Conducting Polymer Films on Zn Deposited Carbon Electrode

Zn plating on carbon steel (CS) was achieved applying current of 4 mA with galvanostatic technique in acidic medium. Zn particles had homogenous, smooth with spherical structure. It was shown that the Zn particles exhibited active behavior on CS substrate. Poly(aniline), poly(pyrrole), poly(N-methylpyrrole) and poly(o-anisidine) homopolymer films were obtained on CS/Zn electrode. Evaluation of anticorrosion performance of these homopolymer coatings in 3.5 % NaCl solution was investigated by using AC impedance spectroscopy (EIS) technique, anodic polarization and the Eocp-time curves. Homopolymer films exhibited significant physical barrier behavior on Zn plated carbon steel, in longer exposure time.

Investigation of the metal–semiconductor interface by equivalent circuit model in zinc phthalocyanine (ZnPc) based Schottky diodes and its charge transport properties

In this report, the ZnPc-based metal–semiconductor (MS) junction Schottky devices (Al/ZnPc/ITO) were fabricated using an effusion cell coating unit. To study the formation of the MS junction, the surface morphology of the deposited ZnPc thin film was investigated using field-emission scanning electron microscope (FESEM) images. The interfacial properties of the MS junction of the Al/ZnPc/ITO configuration were studied using the ac impedance spectroscopy technique within the frequency range of 50 Hz–10 MHz at room temperature (300 K). The bias-dependent impedance spectroscopy was carried out within the voltage range of ±1 V to establish the equivalent circuit of the MS junction Schottky diodes (SDs). The current vs. voltage (I-V) measurements of the fabricated SDs were also conducted to deduce the diode parameters, namely on/off ratio, photosensitivity, ideality factor, barrier height, and series resistance. The charge transport parameters including dc conductivity, mobility and transit time of the charge carriers were also estimated employing the spatial-charge limited current (SCLC) theory, which illustrates the enhanced carrier’s mobility and consequently, the device performance after light irradiation.

Evaluation of PANI-Averraoha bilimbi leaves activated carbon nanocomposite for Cd2+ and Pb2+ removal from wastewater

In current investigation, we synthesized new Polyaniline-Averraoha Bilimbi Leaves Activated Carbon (PANI-ABLC) nanocomposites and utilized as cost effectual for the elimination of Cd2+ and Pb2+ ions from the wastewater. The synthesized nanocomposite was confirmed by Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX), Fourier Transform-Infrared (FT-IR) spectroscopy and X-Ray Diffraction (X-RD) techniques. A batch adsorption study carried in wastewater containing different concentrations of Cd2+ and Pb2+ ions in the temperature range of 303–343 K. The results show that, around 80% of Cd2+ and Pb2+ ions from the wastewater was successfully isolated by using PANI-ABLC nanocomposite. Attempts were made to fit adsorption to different isotherm models. The PANI-ABLC nanocomposite complied Langmuir adsorption model (R2 = 0.999) and pseudo-second order kinetics. Further, maximum adsorption efficiency observed at 0.5 g of Polyaniline-Averraoha bilimbi leaves activated carbon nanocomposites. AC- Impedance Spectroscopy (IS) technique shows that, Polyaniline-Averraoha Bilimbi Leaves Activated Carbon (PANI-ABLC) nanocomposite is suitable for removal of Cd2+ and Pb2+ ions from the wastewater. AC impedance spectroscopy technique study shows that, the process of adsorption was controlled by charge transfer process.

Conductivity Studies in Poly Methyl Methacrylate Based Solid Polymer Electrolytes Complexed with Different Chloride Salts

Ionic conducting polymers are of considerable interest recently, as they have wide range of applications including electrical storage devices. The present study is aimed at designing and characterizing one such ion conducting polymer complexed with various ionic salts. Here, solid polymer electrolyte films consisting of Poly methyl methacrylate (PMMA) complexed with various chloride salts (X) (X= KCl, NaCl, MgCl2) have been prepared by the solvent casting technique. Fourier transform infrared spectroscopy (FTIR) confirmed the formation of polymer-ion complex. The ionic conductivity studies have also been carried out using AC impedance spectroscopy technique. Interestingly, the maximum value of conductivity (8.268 X 10-8 S/cm) has been observed for PMMA/NaCl complex at ambient temperature.

Preparation and conductive properties of double perovskite oxides Ba3Ba1+xTa2-xO9-δ

In this work, Ba3Ba1+xTa2-xO9-δ (x = 0, 0.1, 0.3, and 0.5) double perovskite proton conductors were prepared by solid-state reaction process. Phase compositions and microstructures were characterized by X-ray diffraction and field emission scanning electron microscope techniques. valence and semi-quantitative composition of components were identified by X-ray photoelectron spectroscopy. Conductivities of Ba3Ba1+xTa2-xO9-δ were then measured under various vapor and oxygen pressures by AC impedance spectroscopy technique. Results revealed linear increase in total conductivities of Ba3Ba1+xTa2-xO9-δ oxides as a function of temperature. Ba3Ba1.3Ta1.7O8.55 exhibited the highest total conductivity of 8.41 × 10−4 S cm−1 under humidity and 800 °C. The transport numbers calculated by defect equilibria model revealed. Ba3Ba1+xTa2-xO9-δ oxides as pure proton conductors at 400–800 °C. Also, transport numbers of oxide ions and holes both increased with temperature. Ba3Ba1.3Ta1.7O8.55 illustrated the highest protonic transport number of 0.60 at 800 °C. In sum, these results suggest that Ba3Ba1+xTa2-xO9-δ oxides display excellent proton conductivity.

Electrodegradation of Acid Mixture Dye through the Employment of Cu/Fe Macro-Corrosion Galvanic Cell in Na2SO4 Synthetic Wastewater.

Traditional wastewater purification processes are based on a combination of physical, chemical, and biological methods; however, typical electrochemical techniques for removing pollutants require large amounts of electrical energy. In this study, we report on a process of wastewater purification, through continuous anodic dissolution of iron anode for aerated Cu/Fe galvanic cell in synthetic Na2SO4 wastewater solution. Electrochemical experiments were conducted by means of a laboratory size electrolyzer, where electrocoagulation along with electrooxidation phenomena were examined for wastewater containing Acid Mixture dye. The above was visualized through the employment of electrochemical (cyclic voltammetry and ac impedance spectroscopy techniques) along with instrumental spectroscopy analyses.

Anticorrosive polyaniline-coated copper oxide (PANI/CuO) nanocomposites with tunable electrical properties for broadband electromagnetic interference shielding

This paper presents the electromagnetic interference (EMI) shielding and anti-corrosion characteristics of polyaniline (PANI) coated copper oxide (CuO) nanocomposites. PANI/CuO composites were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), Raman spectroscopy, and thermogravimetry analysis (TGA). Frequency-dependent (AC) conductivity, and dielectric attributes of the composites were analyzed at room temperature in the frequency range of 10 Hz–1 MHz. The AC conductivity and dielectric properties showed tunability with varying concentrations (weight percentage) of CuO particles in PANI. The EMI shielding measurements were carried out in the Ku band (12–18 GHz) frequency range of practical relevance. The results show that, PANI/CuO composites exhibited high electromagnetic interference shielding efficiency due to high surface area and the presence of heterogeneous phase components in their moieties. The anticorrosion behavior of PANI/CuO on mild steel (MS) surface in 5 M HCl corrosive solution was performed by using the atomic absorption spectroscopy (AAS), Tafel plot, and AC impedance spectroscopy techniques. Surface studies were performed by using scanning electron microscopy technique. AAS results indicated that, MS corrosion mitigating efficiency of PANI/CuO nanocomposite is concentration-dependent and protection efficiency is improved with a boost in the PANI/CuO nanocomposite amount. Tafel plots confirmed that, PANI/CuO composite acts as an anodic type of inhibition system. The effect of the protective barrier invisible layer at the surface of the MS was analyzed by Nyquist plot studies and SEM topography showed the mitigation effect of the PANI/CuO system on the MS surface. Finally, our results show that, anticorrosive PANI/CuO can be a good choice for broadband microwave attenuation and EMI shielding applications.

Green synthesis silver nanoparticles via Eichhornia Crassipes leaves extract and their applications

Recent times sustained efforts have been made in the bottom-up approach and biological Ag nanoparticles synthesis, in present work synthesized silver nanoparticles via green synthesis from the Eichhornia crassipes (EC) leaf extract AgNPs at room temperature with pH of 10–12. Synthesized AgNPs characterized thoroughly for phase purity and morphology by various characterization techniques. Phytochemical activities of Eichhornia crassipes (EC) leaf extract were shown that main constituents flavonoids, quercetin enhances the conversion of Ag ​+ ​to Ag0. This is also confirmed through the electronic property (EHOMO and ELUMO) of EC leaf extract, which was analyzed through quantum chemical studies. Further the antibacterial activity of AgNPs was screened on E. coli and S. aureus. The result reveals that AgNPs has good antibacterial properties towards the bacteria E. coli. The AgNPs is dedicated also in testing the effectiveness of aluminum corrosion in the acid system at room temperature using Tafel plots, atomic absorption spectroscopy, and AC impedance spectroscopy techniques. Corroded aluminum pieces were observed by using the SEM technique.

Electric, dielectric and AC electrical conductivity study of Al3+ substituted barium hexaferrite nanoparticles synthesized by Sol-gel auto-combustion technique

Al3+ substituted barium hexaferrite BaFe12-xAlxO19 (where × x = 0.00, 0.25, 0.50, 0.75,1.00) nanoparticles have been prepared by sol–gel auto combustion technique. Two probe method is used to study the electrical resistivity and dielectric properties of aluminium substituted barium hexaferrite. The DC electrical resistivity reveals that the electrical resistivity as well as the activation energy increases with increase in Al3+ content x. On the basis of Maxwell-Wagner and Koop’s theory the dielectric parameters such as dielectric constant (ε′), dielectric loss (ε″) and dielectric loss tangent (tanδ) with frequency are discussed. The dielectric parameters decreases with increase in Al3+ content x. The room temperature AC electrical conductivity measurements were carried out at different frequencies (20 Hz −1MHz). The experimental results indicate that AC electrical conductivity (σac) increases with increase in the frequency, indicating semiconducting behaviour of the samples. The AC impedance spectroscopy technique is used to study internal grain resistance and grain boundary distribution of the prepared aluminium substituted barium hexaferrite samples.

Surface Proton Conduction over Catalyst Support via Chemically Grafted Groups

The proton conduction within a catalyst layer is one of the critical factors affecting the performance of membrane electrode assembly in polymer electrolyte fuel cells. In this work, a simple and effective approach for providing surface proton conduction over carbon supports was developed utilizing chemically grafting SO3H and COOH groups covalently bonded onto carbon surface. A method for accurately measuring the proton conductivity within a catalyst layer was also developed which physically excluded the conductivity contribution from the membrane. This method has several advantages: 1) providing easy sample preparation with high reproducibility, 2) allowing the control of measurement conditions such as gas flow rate, relative humidity and temperature to mimic the exact fuel cell operating conditions. The proton and electron conductivities of the catalyst layers made with and without functional groups at different relative humidifies were characterized with a specially designed 4-probe cell using the AC impedance spectroscopy technique. The results clearly demonstrated that the introduction of functional groups (i.e., SO3H and COOH) did result in a significant improved surface proton conduction over carbon surface and the resulted conductivity depends on the relative humidity, temperature and porosimetry of the carbon blacks.

Aluminum Ion Species Transport in Pure and Additive Modulated Deep Eutectic Solvents (DES) Electrolytes

The need for safe, low cost, high energy and density storage devices is ubiquitous the world over. Satisfying this need requires various energy storage and conversion applications, one of which is the aluminum ion batteries. One problem with expansion in their development and commercialization is the availability of optimized electrolytes. Recently, deep eutectic solvents (DES) have gained attention as electrolytes for energy storage devices. These solvents are similar to ionic liquids, but are generally cheaper and easier to prepare. Additionally, they are known to dissolve metal oxides which plague AIBs operation, and their solubility is dependent on the hydrogen bond donor. Because of their inherent tunability, we studied the effect of AlCl3 concentration (1:1 – 1.7:1 molar ratio), amide type (acetamide (AA), butyramide (BA), propionamide (PA)), viscosity reducing additive type and concentration, on the aluminum ion species and transport in AlCl3:amide DES electrolytes using multi-Nuclear (1H, 27Al) Magnetic Resonance (NMR) and AC Impedance Spectroscopy techniques, as a function of temperature. Below are a few noteworthy observations. Figure 1. VFT plots of the ionic conductivity for AlCl3:AA (left) and AlCl3:PA (right) DES electrolytes. Thirdly, the variable temperature 1H and 27Al spectra and T1 data for the pure and additives included DES electrolytes were very dependent on concentration, additive type and concentration, and species type. For example, in the 1:1 molar ratio electrolyte, the assigned AlCl2(amide)+ species had the longest T1, while the AlCl2(amide)2 + had the shortest. Additionally, the inclusion of additives such as fluoroethylene carbonate (FEC) and propylene carbonate (PC) caused species specific increasing local ion dynamics, possibly through the reduction of bulk viscosity effects and Coulombic interactions. These results and more will be expounded upon in our presentation.Firstly, for both AlCl3:PA and AlCl3:BA DES electrolytes, a maximum in ionic conductivity was observed at the 1.3:1 molar ratio. For AlCl3:AA DES the maximum occurred at the 1.5:1 molar ratio. Secondly, for the three amides conductivity values fell in the range of ~1 – 11 mS/cm over the temperature range of 288 – 363K. Additionally, the temperature dependence displayed curve-like behavior and were fitted using the VFT equation to reveal high levels of fragility and dynamic behaviors similarities to some pure ILs where the effective inter-conversion between the trans and cis conformations of the anion facilitated faster ion dynamics. Figure 1

Aluminum Ion Species Transport in Pure and Additive Modulated Deep Eutectic Solvents (DES) Electrolytes

The need for safe, low cost, high energy and density storage devices is ubiquitous the world over. Satisfying this need requires various energy storage and conversion applications, one of which is the aluminum ion batteries. One problem with expansion in their development and commercialization is the availability of optimized electrolytes. Recently, deep eutectic solvents (DES) have gained attention as electrolytes for energy storage devices. These solvents are similar to ionic liquids, but are generally cheaper and easier to prepare. Additionally, they are known to dissolve metal oxides which plague AIBs operation, and their solubility is dependent on the hydrogen bond donor. Because of their inherent tunability, we studied the effect of AlCl3 concentration (1:1 – 1.7:1 molar ratio), amide type (acetamide (AA), butyramide (BA), propionamide (PA)), viscosity reducing additive type and concentration, on the aluminum ion species and transport in AlCl3:amide DES electrolytes using multi-Nuclear (1H, 27Al) Magnetic Resonance (NMR) and AC Impedance Spectroscopy techniques, as a function of temperature. Below are a few noteworthy observations.Firstly, for both AlCl3:PA and AlCl3:BA DES electrolytes, a maximum in ionic conductivity was observed at the 1.3:1 molar ratio. For AlCl3:AA DES the maximum occurred at the 1.5:1 molar ratio. secondly, the 27Al spectra the 1:1 molar ratio DES electrolytes showed three well resolved peaks at about 101, 88 and 74 ppm, assigned to [AlCl2(amide)2]+, AlCl4 -, and [AlCl2(amide)2]+ respectively. An example of this is shown in Figure 1 for the 1.0:1 (left) AlCl3:PA. With increasing AlCl3 concentration, the narrow well resolved peaks gave way to broadened, asymmetric spectra with two to three visible but not separated peaks. This is also shown in Figure 1 (right) for the 1.3:1 (right) AlCl3:PA. A fourth peak also appeared for DES electrolytes which could be due to free AlCl3:amide species. Figure 1. 27Al variable temperature spectra for 1.0:1 (left) and 1.3:1 (right) AlCl3:Propionamide (PA).Thirdly, like the spectra, the 27Al T1 data for the pure DES electrolytes were very dependent on salt concentration and the species type. For the 1:1 molar ratio electrolyte, the AlCl2(amide)+ species had the longest T1, while the AlCl2(amide)2 +had the shortest. Fourthly, with the inclusion of additives such as propylene carbonate (PC) both the 1H and 27Al T1increased, indicating increasing local ion dynamics possibly through the reduction of bulk viscosity effects and Coulombic interactions. In addition to this, PC also caused additional resolution of the [AlCl2(amide)2]+ species - which was not observed in the pure DES. These results and more will be expounded upon in our presentation. Figure 1

Layered, 2D MnPS3: UV Photodetectors and Humidity Sensors

Two dimensional, layered metal thiophosphates with general formula, MPX3 (M is metal and X is a chalcogen atom) have been emerging as a new class of tunable band gap semiconductors. In this family, manganese phosphosulphide (MnPS3) is a p-type semiconductor with a large band gap of 3.0 eV and hence is a good candidate for UV light detection. In the present study, highly oriented, large-sized crystals have been grown by chemical vapour transport technique with iodine as the transport agent. Field effect transistors based on bulk and few-layer MnPS3 have been fabricated by exfoliating the crystals on Si/SiO2 substrates. Electrical characteristics reveal p-type behaviour with current on-off ratio of ~103 under ambient conditions. The transistor devices are responsive to ultraviolet light with photoresponstivity of 288AW-1 at a wavelength of 365 nm. Fairly high photo gain value of 860 is achieved. Density functional theory (DFT) calculations reveal various parameters that are responsible for the observed p-type conduction observed in electrical transport studies. The MnPS3 semiconductors show very good humidity sensing behaviour. Liquid exfoliation technique has been used to exfoliate the bulk crystals into few-layer 2D MnPS3. Very stable, few layer colloids of MnPS3 is vacuum filtered and the membrane is transferred on to interdigitated electrodes to form the sensing device. The results revealed that the conductivity of the films increases five to six orders of magnitude with a change in relative humidity (RH) from 0% to 98%. A fast response and recovery time of ~1-2 s and ~ 4 s are observed respectively. AC impedance spectroscopy and Raman spectroscopy techniques are utilized to understand the sensing mechanism. Further, the sensor has been shown to monitor human breath and water evaporation from skin without any physical contact.

Antifebrin Drug Prepared via One-Stage Green Method as Sustainable Corrosion Inhibitor for Al in 3 M HCl Medium: Insight from Electrochemical, Gasometric, and Quantum Chemical Studies

The medicinal compound antifebrin was prepared in the laboratory via one stage (green method) by using aniline, glacial acetic acid, and zinc dust. The investigation was aimed at ascertain a possibility of utilizing the medicinal compound to originate a corrosion inhibitor for Al in a 3 M HCl solution. In the present article, the usefulness of antifebrin to inhibit the Al corrosion in 3 M HCl solution was examined by the Tafel plot, AC impedance spectroscopy, gasometric and quantum chemical techniques. The Tafel plot results show that concentration of antifebrin has a positive effect on the inhibition efficiency. The Tafel plot also reveals that this medicinal compound inhibits the acidic corrosion of aluminum by a mixed mode. Impedance spectroscopy results show that corrosion resistance of Al in a 3 M hydrochloric acid was improved by antifebrin. For better understanding the relationship between the antifebrin molecular structure and inhibitory ability, quantum calculations (by using Argus Lab = latest version) were performed. Surface studies were carried out by scanning electron microscopy. The Langmuir plot confirms the chemical adsorption mechanism on the Al surface in a 3 M HCl solution in the presence of antifebrin.

Influence of processing conditions on the ionic conductivity of holmium zirconate (Ho2Zr2O7)

Nanopowders of holmium zirconate (Ho2Zr2O7) synthesised through carbon neutral sol-gel method were pressed into pellets and individually sintered for 2 h in a single step sintering (SSS) process from 1100 °C to 1500 °C at 100 °C interval and in a two step sintering (TSS) process at (I) −1500 °C for 5 min followed by (II) - 1300 °C for 96 h. Relative density of each of the sintered pellet was determined using the Archimedes’ technique and the theoretical density was calculated from crystal structure data. Grain size was obtained from SEM micrographs using ImageJ. Pellets processed by TSS have been found to be denser (98 %) with less grain growth (1.29 μm) as compared to the pellets processed using SSS process. Ionic conductivity of Ho2Zr2O7 pellets sintered by two different processes was measured using ac impedance spectroscopy technique over the temperature range of 350 °C–750 °C in the frequency range of 100 mHz–100 MHz for both heating and cooling cycles. The temperature dependence of bulk (2.67⨯10−3 Scm−1) and grain boundary (2.50⨯10−3 Scm−1) conductivities of Ho2Zr2O7 prepared by TSS process are greater than those processed by SSS process suggesting the strong influence of processing conditions and grain size. Results of this study, indicates that the TSS is the preferable route for processing the holmium zirconate as it can be sintered to exceptionally high densities at lower temperature, exhibits less grain growth and enhanced ionic conductivity compared with the samples processed by SSS process. Hence, holmium zirconate can be considered as a promising new oxide ion conducting solid electrolyte for intermediate temperature SOFC applications between 350 °C and 750 °C temperature range.

Electrical investigation on thiophene–indole conducting copolymers as-synthesized through in situ chemical copolymerization route

In this communication, a series of thiophene–indole conducting copolymers are successfully synthesized via in situ chemical oxidative copolymerization of thiophene and indole monomers using anhydrous FeCl3 as an oxidant. Fourier-transform infrared spectroscopy studies depict the structural confirmation. X-ray diffraction profile indicates the amorphous nature of the as-synthesized copolymeric samples. The electrical conductivity, dielectric properties and relaxation model are indeed studied using AC impedance spectroscopy technique in the frequency and temperature ranges 20 Hz–1 MHz and 303–393 K, respectively. The temperature dependence of electrical conductivity of as-prepared copolymeric samples followed the Arrhenius relation. The variation of AC conductivity with frequency obeys the Jonscher’s power law. The electric modulus spectra showed the non-Debye nature of the studied copolymeric materials. Schematic for in situ synthesis of thiophene–indole conducting copolymer through chemical oxidative copolymerization route

Electrochemical Impedance Spectroscopy as a Practical Tool for Monitoring the Carbonation Process on Reinforced Concrete Structures

Carbonation results in a decrease in the pH of the cementation matrix when CO2(g) from the environment diffused into the concrete structure that can cause the loss of passivity condition on the reinforcing steel surface and leads to early failure of concrete by corrosion attack. There are several monitoring techniques to evaluate the process of lowering the pH in the concrete, named carbonation depth progress. In this research, an electrochemical AC impedance spectroscopy (EIS) technique has been used as an effective laboratory tool for monitoring the evolution of the carbonation progress. A comparison with the traditional phenolphthalein colorimetric technique was also discussed here. Particularly, monitoring is achieved by measuring the change in electrical resistance (Rpo) and capacitance (Cpo) of the concrete bulk, which is obtained from the semicircle at high-frequency region of a typical EIS diagram. According to the EIS results, carbonation progress was observed by a significant increase in the diameter of the semicircle, thus demonstrating the increase in resistivity of ions transmission due to blockade of pores by precipitation of CaCO3 compounds. Furthermore, it was possible to predict the specific time at which the carbonation front reaches the steel-rebar interface at low frequency region and possibly starting a considerable corrosion attack. Finally, the results suggested that EIS technique could be considered a practical tool for evaluating the carbonation progress of reinforced concrete structures without causing structural damage, in addition to the sensitivity of this technique with sufficient accuracy to predict the activation of the reinforcing steel.

Preparation and Properties of a High-Performance EOEOEA-Based Gel-Polymer-Electrolyte Lithium Battery.

Gel polymer electrolyte (GPE) is a promising candidate for lithium-ion batteries due to its adhesion property (like a solid), diffusion property (like a liquid), and inhibition of the growth of lithium dendrite. In this paper, 2-(2-ethoxyethoxy)ethyl acrylate (EOEOEA) and LiBF4 electrolyte were mixed as precursors of gel polymer electrolytes. Through thermal curing, a thermally stable GPE with high ionic conductivity (5.60 × 10−4 s/cm at 30 °C) and wide room temperature electrochemical window (4.65 V) was prepared, and the properties of the GPE were measured by linear sweep voltammetry (LSV), AC impedance spectroscopy, Thermogravimetric analysis (TG), and X-ray diffraction (XRD) techniques. On the basis of the in-situ deep polymerization on a LiFePO4 electrode and cellulose membrane in a battery case, EOEOEA-based GPE could be derived on both LiFePO4 electrode and cellulose membrane. Meanwhile, the contact between GPE, LiFePO4 electrode, and lithium electrode was promoted. The capacity retention rate of the as-prepared LiBF4-EOEOEA 30% gel lithium battery reached 100% under the condition of 0.1 °C after 50 cycles, and the Coulombic efficiency was over 99%. Meanwhile, the growth of lithium dendrite could be effectively inhibited. GPE can be applied in high-performance lithium batteries.

Crosslinked thermoelectric hydro-ionogels: A new class of highly conductive thermoelectric materials

In this work, a new class of highly-conductive chemically cross-linked gel has been synthesized by the confinement of water and IL N, N, N triethyl octyl ammonium bromide ([N2228] Br) in polyethylene glycol dimethacrylate (PEGDMA) matrix, using in situ thermally initiated radical polymerization loaded with 1 wt% free radical initiator azobisisobutyronitrile (AIBN). This novel gel was named as hydro-ionogel (HIG). The thermoelectric properties of HIG such as ionic conductivity, Seebeck coefficient, and thermal conductivity were measured and owing to its high thermoelectric performance, we referred to this as crosslinked thermoelectric hydro-ionogel, henceforth will be denoted by X-TEHIG. For all the measurements, coin cells were fabricated using commercial LIR 2032 stainless steel battery casings with X-TEHIG sandwiched between the two graphene electrodes. The ionic conductivity of X-TEHIG was examined via AC impedance spectroscopy technique by using a Gamry apparatus. Remarkably, the ionic conductivity of X-TEHIG was higher than that of neat [N2228] Br. A linear increase in ionic conductivity of X-TEHIG as a function of temperature was recorded that showed a considerably higher value of 74 mScm−1 at 70 °C. The origin of this high conductivity is attributed to interactions between PEGDMA monomers and cations and anions of the IL and formation of hydrogen bonds between water and Br− anion, OH⋯Br−. X-TEHIG demonstrated a higher Seebeck coefficient of 1.38 mVK−1. The Fourier transform infrared (FTIR) spectroscopy results revealed the successful polymerization of X-TEHIG by the disappearance of CC peak of methacrylate group in the spectrum of PEGDMA. These results suggest that X-TEHIG may be a potential candidate for thermoelectric applications owing to their high values of ionic conductivity and Seebeck coefficient.