bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on the Interfacial Impedance of Superconcentrated Non-Aqueous Electrolytes in Contact with Li-Ion Conductive Ceramic Membranes
Authors: Arruda Thomas M , Donnelly Daniel J , Patrissi Charles J.
Published: February 2020

Superconcentrated nonaqueous electrolytes have recently received considerable attention for their various unusual functionalities within rechargeable batteries.1,2 These include high reductive and oxidative stabilities and enhanced thermal stability of the solvent. Our research focuses on the interfacial effects of superconcentrated lithium salts in aprotic solvents, on ceramic Li-ion conductive membranes of varying porosity. Electrochemical impedance spectroscopy was employed with a four-electrode setup to study the interfacial kinetics, and was processed by analyzing the Nyquist plots. These methods revealed promising trends that may lead to the finding an optimal concentration range of LiTFSI in DMC solvent with high porosity ceramic membranes, that would minimize interfacial impedance. This presentation will highlight some of our recent findings.

1. Y. Yamada, M. Yaegashi, T. Abe, and A. Yamada, Chem. Commun., 49, 11194–11196 (2013) http://dx.doi.org/10.1039/C3CC46665E.

2. Y. Yamada and A. Yamada, J. Electrochem. Soc., 162, A2406–A2423 (2015) http://jes.ecsdl.org/content/162/14/A2406.abstract.
Redox-Dependent Binding to an Electroactive Urea: Comparison of One and Two Electron Redox Couples
Authors: Logan Kyle , Clare Laurie A. , Smith Diane K.
Published: February 2020

In previous work in our lab, the redox-dependent binding behavior of a phenylene-diamine urea, UHH, was investigated in the presence of different guests in CH2Cl2. The urea functionality contains two good H-donors in the two urea NH bonds (a DD motif) that are capable of H-bonding with two appropriately spaced H-acceptors (AA motif). An example is 1,8-naphthyridine, naph, which contains two pyridine-type N’s appropriately spaced and orientated to H-bond to the two NH’s in UHH. 1H NMR studies indicated a modest Kbinding of 30 M-1 in CH2Cl2 between UHH and naph. The expectation was that oxidation of the phenylenediamine couple in UHH would increase the acidity of one of the NH’s leading to stronger H-bonding and a negative shift in the observed redox potential upon addition of naph. However, instead what happened was that the current for the oxidation increased with little change in peak potential. This can be explained by proton transfer from the UHH radical cation to the naphthyridine. The resulting neutral radical will be immediately oxidized by a second electron leading to the increase in current. The proton transfer will change the H-bonding motif from AA-DD to AD-DA, which is inherently weaker because of unfavorable secondary interactions. In addition because of the two electron oxidation, both binding partners in the resulting complex, (naphH+)(UH+), will be positively charged. Therefore it is not surprising that the H-bonding does not strengthen upon oxidation. In this study the phenylenediamine couple is replaced by a ferrocene, FcUHH, which is only capable of a one electron oxidation. Cyclic voltammetry experiments will be run with FcUHH and naphthyridine to see if eliminating the possibility of the second electron transfer prevents proton transfer and results in the expected stronger H-bonding to the oxidized form.
Bi-Continuous Nanoporous Metal Formation Via Compound Decomposition
Authors: Chen Qing , Wang Congcheng
Published: February 2020

The spontaneous formation of bi-continuous nanoporous (BNP) metal from dealloying, i.e. the selective dissolution of an alloy, has fascinated generations of researchers to pursue its significance in corrosion and, increasingly, in catalysis. As the structure possess interpenetrating pores and metal ligaments at length scales down to a few nanometers, it provides a large yet highly accessible area comprising a high population of surface steps; these attributes promote BNP metal as the best catalysts for a variety of catalysis challenges. However, one of the obstacles facing a wider application of the BNP metal is the demanding preparation of the starting materials, i.e. a homogeneous alloy. Here we present that the step of alloy preparation can be completely eliminated from the fabrication of BNP metal by adopting an alternative route of reduction-induced decomposition. In this decomposition process, ionic or covalent compounds (e.g. AgCl and CuO) can be chemically reduced to form BNP metal similar if not identical to that through dealloying. We use a combination of characterization techniques, including electron microscopy, underpotential deposition-based area measurement, and small-angle X-ray scattering, to show the structural resemblance of the decomposed materials to their dealloyed counterparts. At the same time, the differences between the two types of structures and their potential structural and functional impacts will also be discussed. We believe that the introduction of decomposition as a low-cost yet flexible alternative will enable a wide adoption of BNP metal as active yet affordable catalysts.

McCue, I.; Benn, E.; Gaskey, B.; Erlebacher, J. Annu. Rev. Mater. Res.
2016, 46 (1), annurev-matsci-070115-031739;

Chen, Q. J. Electrochem. Soc.
2014, 161 (10), H643–H646.
Mechanical and Electrical Properties of Electrostatic Sprun Carbon Nanotubes Embedded in P3HT:PCBM
Authors: Fang Te-Hua , Chiu Zhe-Wei , Hsiao Yu-Jen
Published: February 2020

Optical and electrical properties of organic photovoltaic devices are investigated. The electrostatic spray is used to deposit a hybrid film (P3HT : PCBM / Carbon nanotubes) with morphology and optical characteristics onto photovoltaic devices. The surface roughness increase with increasing carbon nanotubes content. The device takes advantage of the high current density, power conversion efficiency, and low cost. Carbon nanotubes improves the shortcircuit current density and power conversion efficiency. The highest performance is obtained with 0.5wt% carbon nanotubes content, with a current density of 7.33 mA·cm2 and a power conversion efficiency of 2.41%.
Use of Microdischarge Lithography for Development of Organic Electronic Devices over Large Areas
Authors: Alvarez Angel Luis , Borrás Fernando , Moreno Jorge Sebastián , García-Vélez Miguel , Jiménez-Trillo Juan , Coya Carmen
Published: February 2020

The concept of 'displays everywhere', which may be extended to wearable sensors, signal tags or energy devices, implies ubiquity of electronic devices not only in walls or appliances but integrated in all kind of domestic objects, such as clothes, bags or wrappings, and is expected to preside over our daily lives in the near future. For this expectation to succeed, Electronics industry must face compatibility with three new paradigms: flexible substrates -to be adapted to different surfaces and geometries-, large areas (eventually up to square meters), and lightness. In any case, this revolution can only take place from a drastic reduction of the production costs. As it is well known, these paradigms are difficult to access solely for conventional microelectronics technology based on silicon or other crystalline materials, and many alternatives based in new materials and procedures have been proposed. Thus, a manufacturing facility based in the roll-to-roll (R2R) technology is considered a suitable candidate to achieve high yield over large areas in a cost effective way. In consequence, those patterning techniques compatible with R2R production lines are receiving enhanced attention.

In this contribution, we exploit the possibilities of a dry and subtractive lithography based on electrical microdischarges to pattern both electrodes, cathode and anode, of organic devices, particularly displays based in organic light emitting diodes (Fig. 1). Using a homemade prototype rated at technology readiness level 4, we demonstrate that electrical discharge lithography may overcome many obstacles such as tilt correction and relocation after processing, avoiding the use of masks and many of the photolithographic steps. This is thanks to the electrical monitoring during operation as well as a precise electronic control of the position, with 1 µm reproducibility. Since sparks are very fast processes (range of few µs or less) features may be performed at speeds of tens mm/s, ensuring scalability to large areas (cms), and hence compatibility with high throughput manufacturing lines. Of particular interest results patterning of graphene as electrode, due to the practical absence of residues under electrical discharges. Other advantages and drawbacks will be discussed, as well as physical aspects involved.

Figure 1
Effect of Inserting Nanoscale-Thick Inorganic Interlayer Between Metal Electrode and Organic Layers on Photo-Sensitivity Enhancement of Organic Photo Diodes
Authors: Park Joo-Hyeong , Song Seung-Hyun , Kim Min-Won , Kown Hyo-Jun , Kim Jae-Gon , Jung Ui-Hyeon , Baik Hyo-Won , Park Jea-Gun
Published: February 2020

The conventional silicon based photo diodes have high photoelectric conversion efficiency and photosensitivity. However, inorganic based photo diodes have a low visible-wavelength sensitivity due to their infrared-wavelength absorption. Recently, organic based photo diodes (OPDs) have been greatly attracted due to their flexibility, a low production cost, and a high photosensitivity in visible wavelength ranges.[1, 2]

In this work, we investigated the effect of inserting inorganic interlayer between metal electrode and organic layers in order to enhance photosensitivity of OPDs. The device structure was consist of vertically stacted bottom indium-tin-oxide (ITO) electrode/bottom inorganic interlayer (NiOx)/organic layer (DMQA:Me-PTC)/top inorganic interlayer (MoOx)/top aluminum electrode on a glass substrate. The bottom NiOx inorganic interlayer was inserted between bottom ITO electrode and DMQA:Me-PTC photo-organic layer and its thickness was varied from 1 to 5 nm. It was found that the highest photocurrent/dark current ratio of OPDs was 1.34 x 104 at 4-nm-thick NiOx. In addition, the top MoOx:Al (1:1) inorganic interlayer was inserted between top aluminum electorde and DMQA:Me-PTC photo-organic layer and its thickness was varied from 1 to 3 nm. It was also observed that the highest photocurrent/dark current ratio was 4.51 x 104 at 2-nm-thick MoOx:Al. In our presentation, we will present the mechanism by which the photosensitivity is enhanced by varying inserted inorganic interlayer (NiOx or MoOx) via investigating the dependency of energy band gap on the inserted inorganic interlayer thickness and that of the chemical composition profiles of OPDs.

* This work was financially supported by LG Electronics Inc. and Brain Korea 21 Plus Program in 2017.

[1] Baeg, K.-J., Binda, M., Natali, D., Caironi, M. & Noh, Y.-Y. Organic light detectors: photodiodes and phototransistors. Adv. Mater. 25, 4267–4295 (2013).

[2] Yao, Y. et al. Plastic near-infrared photodetectors utilizing low band gap polymer. Adv. Mater. 19, 3979–3983 (2007)

Figure 1
Electrolyte Influence in Developing a High-Capacity, Reversible Lithium-Oxygen (Lithium-Air) Battery
Authors: Burke Colin M , McCloskey Bryan D
Published: February 2020

The nonaqueous lithium-oxygen (also called lithium-air) electrochemistry has an extraordinarily high theoretical specific energy, but critical electrochemical challenges prevent the realization of a high-capacity, reversible battery. Consisting of a lithium-metal negative electrode, an anhydrous, organic solvent-based lithium electrolyte, and a gaseous oxygen-saturated porous carbon positive electrode, the battery operates via the formation and decomposition of lithium peroxide (Li2O2). Unfortunately, in the most stable, ether-based electrolytes studied to-date, Li2O2 forms as a thin film on the carbon surface. As Li2O2 is an insulator, the thin film quickly leads to a large increase in the surface overpotential, effectively shutting off the battery before a high capacity can be achieved. Additionally, both the most stable electrolytes and porous carbons studied to-date still exhibit electrochemical decomposition in the presence of Li2O2 in operating cells, leading to parasitic products and poor cyclability.

In this work, we present electrolyte salt and solvent considerations toward addressing these challenges. We will particularly focus on recent reports that the introduction of lithium iodide (LiI) salt to a water-contaminated ether-based electrolyte induces a 4e- per O2 reduction reaction forming lithium hydroxide (LiOH) rather than the typical 2e- per O2 reduction reaction forming Li2O2.1,2 This could potentially mitigate both charge transport and instability issues related to Li2O2 by entirely changing the discharge electrochemistry. We present our recent quantitative analysis of the influence of LiI and H2O on the electrochemistry in a typical ether-based Li-O2 battery via differential electrochemical mass spectrometry and titrations of extracted cathodes.3 We confirm that LiI and H2O promote the efficient production of LiOH on discharge, but we find that LiOH is not reversibly oxidized to O2 on charge. Rather, the charge electrochemistry is a complicated mix of redox shuttling and side reactions. We hope to inspire further research toward understanding the complex chemistry involved upon the addition of redox mediators to lithium-oxygen batteries.

(1) Liu, T.; Leskes, M.; Yu, W.; Moore, A. J.; Zhou, L.; Bayley, P. M.; Kim, G.; Grey, C. P. Science
2015, 350, 530.

(2) Kwak, W.-J.; Hirshberg, D.; Sharon, D.; Shin, H.-J.; Afri, M.; Park, J.-B.; Garsuch, A.; Chesneau, F. F.; Frimer, A. A.; Aurbach, D.; Sun, Y.-K. J. Mater. Chem. A
2015, 3, 8855.

(3) Burke, C. M.; Black, R.; Kochetkov, I. R.; Giordani, V.; Addison, D.; Nazar, L. F.; McCloskey, B. D. ACS Energy Letters
2016, 1, 747.
Properties of Ionic Liquids and Their Performance As Electrolytes for Sodium Batteries
Authors: Hilder Matthias , Saurel Damien , Gonzalo Elena Candida , Rojo Teófilo , Armand Michel , MacFarlane Douglas R , Howlett Patrick C , Forsyth Maria
Published: February 2020

With the world facing a global energy crisis research efforts have been focussing on alternative energy storage solutions, A promising and inexpensive alternative to the dominating lithium battery technology are sodium batteries, which are particularly interesting for large scale energy storage.

Ionic liquids (ILs) are novel electrolyte systems which have the potential to be compatible to support the electrochemistry of sodium while replacing commonly used organic solvent electrolytes, thus improving the safety of such devices.

Here the physicochemical properties of three bis(fluorosulfonyl)imide (FSI) based ionic liquid electrolytes with small alkylphosphonium cations or an alkyletherammonium cation (P111i4FSI, P1i4i4i4FSI, N2(2O2O1)3FSI) were investigated including the thermal properties, ionic conductivity and viscosities. The phosphonium ILs showed particularly high conductivities (0.94mScm-1 for P111i4FSI at 50°C) while also having the highest decomposition temperatures (320°C). All IL solutions with NaFSI showed very stable Na symmetric cell cycling with low overpotentials (P111i4FSI:NaFSI 100mV at 1mAcm-2) making them promising electrolytes for sodium batteries.

The electrolytes were cycled against NaPO4 (NFP) cathodes and layered transition metal oxides (P2-Na2/3[Fe2/3Mn1/3]O2, O3-Na2/3[Fe2/3Mn1/3]O2, P2-Na2/3[Mn0.8Fe0.1Ti0.1]O2). The highest stability and capacity was observed for the P111i4FSI electrolyte, particular with the O3-Na2/3[Fe2/3Mn1/3]O2 cathode. Surprisingly the NFP electrodes showed very stable cycling.

On selected cells post-cycling analysis was performed. While the electrolyte is not compromised, there is spectroscopic evidence for the formation of a stabilising solid electrolyte interface on the sodium metal anode as well as on the cathode. In addition the cathode morphology changes.

In summary ionic liquid electrolytes match or out perform conventional organic solvent electrolytes in terms of performance at elevated temperatures, capacity, cycle stability and safety.
Nanobatteries for the Development of New Materials for Anodes
Authors: Seminario Jorge M. , Galvez-Aranda Diego E , Ponce Victor
Published: February 2020

Rechargeable lithium-ion batteries are one of the most used devices for energy storage but still a lot of researcher needs to be performed to improve their cycling and storage capacity. The most used material anodes is graphite with a theoretical capacity of 372 mAh/g. Thus, silicon have been proposed as an anode material because its large capacity of 3,579 mAh/g. Several experimental and theoretical-computational works have been done to find out how silicon behaves during lithiation (charging of the battery), especially when the silicon anode increases its volume up to 300% due to the lithiation process. In order to understand the mechanics and chemistry of silicon electrodes and to prevent undesirable effects such as the cracking of the anode, research have been performed on nanoscale approaches to a fully nanobattery. We study both, the graphite and the silicon nanocrystal anodes, performing molecular dynamics atomistic simulations. In this effort in progress we are focusing on the mechanical properties, such as swelling, alloying mechanism, and amorphization of the anode material during the first charging cycle and also the electrical properties such as polarization and current. The nanobattery includes LiCoO2 cathode; the electrolyte solution contains ethylene carbonate, as well as hexafluorophosphate and Li-ions. In these preliminary models, a solid electrolyte interface (SEI) is not included yet. An external electric field is applied to emulate the charging process causing the migration of the Li-ions from the cathode, diffusing through the electrolyte to finally get into the anode. We immediately observe during charging (i.e., when an external electric field is applied) of the nanobattery, the Si anode changes gradually into a LiSi alloy at temperatures below 360 K, using an NVT ensemble. We obtained the drift velocity of the Li-ions during the amorphization of the silicon nanocrystal as the original volume of the anode increases. For the graphite anode, the full lithiated state is achieve when the initial structure C changes into LiC6, storing the Li-ion between the layers of the graphite, thus we were able to compare energy, temperature, and electrical properties such as current, resistance, current density, conductivity and resistivity. Our model can be used to study the mechanisms taking place in the electrolyte, cathode, and especially for new materials for the anode.
Electrochemical Characterization of Silicon Nanocrystals Embedded in Alloy Matrix As Anode Materials for Lithium-Ion Cells
Authors: Kim Sang-Hyung , Yook Seung Hyun , Kim Seon-Kyong , Park Cheol-Ho , Kim Dong-Won
Published: February 2020

Silicon has been regarded as one of the most promising anode materials to increase the energy density of lithium-ion batteries by replacing graphite materials due to its high theoretical capacity.1 However, the practical application of silicon materials in lithium-ion batteries is hampered by the large volume changes that occur during repeated cycling, which result in the cracking of the electrode, loss of electrical contact, unstable solid electrolyte interphase (SEI) formation, and eventually rapid capacity fading upon cycling.2,3 The promising approach to overcome the above problems is the utilization of active-inactive alloy systems, where the electrochemical reaction occurs in the active phase and the inactive phases help to improve electronic conductivity and act as a volume buffer. In the present work, we synthesized silicon alloys composed of silicon nanoparticles embedded in Cu-Al-Fe matrix phases. The matrix phases have a mechanical property to endure the stress generated by the volume expansion of Si during cycling in addition to high electrical conductivity for fast electron transfer to silicon. This strategy resulted in enhanced cycling performance in terms of discharge capacity, capacity retention and rate capability. These superior performances could be attributed to its unique structure with silicon particle embedded by alloy matrix, which could effectively accommodate the large volume change during cycling and provide continuous electronic pathway in the electrode. Detailed characterization of the silicon alloy materials along with their electrochemical performance as anode in lithium-ion cells will be presented.

References

1. V. Etacheri, R. Marom, R. Elazari, G. Salitra and D. Aurbach, Energy Environ. Sci., 4, 3243 (2011).

2. B. Key, R. Bhattacharyya, M. Morcrette, V. Seznec, J.-M. Tarascon and C. P. Grey, J. Amer. Chem. Soc., 131, 9239 (2009).

3. M. T. McDowell, S. W. Lee, W. D. Nix and Y. Cui, Adv. Mater., 25, 4966 (2013) .
(Invited) Teslaphoresis of Carbon Nanotubes
Authors: Cherukuri Paul
Published: February 2020

Teslaphoresis is the directed motion and self-assembly of matter by radiofrequency energy transmitted from a Tesla coil. Carbon nanotubes placed within the Teslaphoretic field polarize and rapidly self-assemble into wires (< 5 s) that span from the nanoscale to the macroscale, the longest thus far being 15 cm. We also show the self-assembly of long nanotube wires at a remote distance (> 30 cm away from the antenna) and that the transmitter wirelessly powers nanotube-based LED circuits that harvest energy directly from the Teslaphoretic field. Furthermore, we found that individualized carbon nanotubes in suspension self-organize into large-scale, parallel arrays on a substrate with high fidelity alignment to the direction of the transmitted electric field. Thus, the Teslaphoretic system may be an effective tool for scalable manufacturing of carbon nanotube transistors and conductive fibers.
(Invited) Effect of Physisorbed Oxygen on the Photoluminescence of Single-Walled Carbon Nanotubes Suspended By Single-Stranded DNAs
Authors: Bachilo Sergei M. , Zheng Yu , Weisman R. Bruce
Published: February 2020

For more than a decade, DNA and oligonucleotides of single-strand DNA (ssDNA) have studied as agents for dispersing single-walled carbon nanotubes (SWCNT), with the goals of potential biomedical applications and the selective sorting of specific (n,m) structures from as-produced inhomogeneous mixtures. We have recently discovered that SWCNTs suspended by ssDNA oligos in water show rather strong quenching from dissolved molecular oxygen. In many cases dissolved oxygen in equilibrium with 1 atm partial pressure of O2 decreases the SWCNT fluorescence intensity by a factor of two, and for some systems the quenching factor is two in air-saturated solutions and reaches three under 1 atm of pure O2. We find that the quenching depends on (n,m) species and ssDNA sequence, in addition to some other experimental parameters. The effect varies smoothly with dissolved oxygen concentration and is fully reversible on purging with other gases such as argon or nitrogen. The quenching effect appears and disappears on a sub-second time scale.

An important finding is that the extent of oxygen quenching correlates with the apparent affinity between the DNA oligo and the SWCNT species. Combinations thought to give strong coating show weak quenching, possibly because of reduced exposure of the nanotube surface to the surrounding solution. Thus, this effect can provide a simple way to identify special affinities just by measuring fluorescence changes when dissolved oxygen is displaced by inert gases. To help understand the mechanism of the quenching effect and its potential value in other applications, we have studied a variety ssDNA oligos, including those containing only one nucleotide. We have also studied the effect with other dispersing agents and surfactants, quantified the dependence of quenching on oxygen concentration, analyzed fluorescence spectral shifts caused by dissolved oxygen, and explored the quenching effect in solid nanotube films and in solutions modified by addition of polymers and other chemicals. We will present the results of those experiments and our proposed mechanism for the effect.
(Invited) Carbon Nanotubes from Synthesis, Assembly to Electrochemical Sensors
Authors: Alvarez Noe , Zhao Daoli , Heineman William R. , Shanov Vesselin N. , Siebold David
Published: February 2020

The unique physical properties of individual Carbon Nanotubes (CNTs) surpass the properties of many advanced materials available today. Due to their large surface area, chemical stability, and electrical conductivity, they are the most promising candidates for a large number of electroanalytical applications. A material for these applications requires high purity CNT assemblies like fibers and films, that have good electrical conductivity, in some case additional insulation coatings. This talk will report the synthesis of catalyst free CNTs, their assembly into ribbons at 15.9 m/s speed, fiber processing and polymer coating into a micro-cable format. CNT micro-cable was used for detection of toxic metals contaminants in H2O, that are considered as the most significant potential threats to human health by ATSDR and EPA. Polystyrene coated CNT fiber was used as the working electrode; bare CNT thread was used as the auxiliary electrode; and a pseudo-reference electrode was fabricated by electroplating CNT fiber with Ag that is subsequently anodized in chloride solution to form a layer of AgCl. The Ag/AgCl coated CNT fiber electrode provides stable potential comparable to the conventional liquid-junction type Ag/AgCl reference electrode, while bare CNT fiber auxiliary electrode provided a stable current comparable to a Pt wire auxiliary electrode. This all-carbon CNT fiber three electrode cell is evaluated for simultaneous detection of trace levels of heavy metal ions by anodic stripping voltammetry (ASV). Hg2+, Cu2+ and Pb2+ in H2O were detected successfully, and the detection limits are 1.05 nM, 0.53 nM and 0.57 nM for Hg2+, Cu2+ and Pb2+, respectively. These electrodes significantly reduce the dimensions of the conventional three electrode electrochemical cell and have the potential to become low cost and disposable sensor.
Carbon Nanotube Reinforced Structural Composite Supercapacitors
Authors: Westover Andrew S , Teblum Eti , Schauben Deanna , Yitzhak Anat , Muralidharan Nitin , Muallem Merav , Nessim Gilbert , Pint Cary L.
Published: February 2020

Carbon nanotubes (CNT) lie at the crossroads of a multitude of different next generation technologies. Among the most promising of these are structural reinforcement of composites and high energy density supercapacitors. Our work presents a unique approach where CNT grown on stainless steel meshes are used to simultaneously mechanically reinforce a structural composite and function as a high energy density supercapacitor electrodes. The multifunctional design is enabled via an epoxy-ionic liquid matrix/electrolyte and with alternating layers of insulating fiberglass or Kevlar and CNT grown on steel mesh. The resulting composite energy storage devices exhibit mechanical strength greater than 85 MPa approaching that of commercial composites and with an energy density of up to 3 mWh/kg for a fully packaged system. Furthermore in-situ mechano-electro-chemical tests demonstrate that the capacitance is completely maintained throughout the elastic regime up to the maximum tensile loading >85 MPa.
(Invited) Ultrafast Spectroscopy of Doped Carbon Nanotubes
Authors: Hertel Tobias , Eckstein Klaus
Published: February 2020

We will report on an investigation of exciton and trion dynamics in chemically- or electrochemically-doped semiconducting single-wall carbon nanotubes using VIS and NIR femtosecond time-resolved pump-probe spectroscopy.
A Novel Ceramic-Polymer Hybrid Electrolyte for Lithium Batteries
Authors: Zekoll Stefanie , Marriner-Edwards Cassian , Hekselman Aleksandra K. , Kasemchainan Jitti , Kuss Christian , Armstrong David , Cai Dongyu , Wallace Robert , Richter Felix Herrmann , Thijssen Job H. J. , Bruce Peter G.
Published: February 2020

Lithium (Li) metal is being intensively pursued as a negative electrode due to its high specific capacity. Yet, irreversible Li loss, dendrite formation of plated Li metal, and short circuiting, when being cycled as an electrode in battery cells presently impede its use. Furthermore, the flammability of liquid electrolytes poses a severe safety hazard. Replacement of organic liquids by solid electrolytes could pave the way for using Li metal, simultaneously improving specific energy and battery safety.

Significant attention has been paid to ceramic electrolytes due to their high Li-ion conductivity at room temperature and robustness. Nevertheless, processing and manufacturing of the ceramics into sufficiently thin, highly dense, pinhole-free sheets, required for high specific energy and power devices, remains an active challenge. Additionally, the electrolyte must maintain contact with the solid electrodes while simultaneously inhibiting Li dendrites as well as be durable towards electrode volume changes and to external shock.

Polymer electrolytes have been developed for a number of years. The advantages include good adhesion and contact to the electrodes. Still, their low conductivity at room temperature, especially in solid polymer electrolytes, along with their limited capability of suppressing Li dendrite formation, are persistent drawbacks.[i]

To date, ceramic and polymer electrolytes remain a challenge. Hybrids with particulate ceramics embedded in polymer electrolytes have been investigated to improve the conductivity and mechanical properties.
[ii]
Our approach is to create continuously ordered hybrid electrolytes, which allows modification of the mechanical properties of the hybrid while retaining a high ionic conductivity through the ceramic phase.

The ionic conductivity of the hybrid electrolyte is 1.5 x 10-4S/cm at 25 °C. The results of different ceramic-polymer compositions indicate that the mechanical properties of the hybrids can be adjusted by the presented approach. Electrochemical, mechanical, and microstructural characterizations of the hybrid will be reported.

[i] G. M. Stone, S. A. Mullin, A. A. Teran, D. T. Hallinan Jr., A. M. Minor, A. Hexemer, N. P. Balsara, J. Electrochem. Soc., 2012, 159, A222–A227.

[ii] Y.-C. Jung, S.-M. Lee, J.-H. Choi, S. S. Jang and D.-W. Kim, J. Electrochem. Soc., 2015, 162, A704–A710.
Electrocatalytic Properties of Vanadate Glass for Metal-Air Rechargeable Battery
Authors: Miyamoto Hajime , Yuasa Masayoshi , Nishida Tetsuaki , Oka Nobuto
Published: February 2020

A metal-air battery has a high energy density because they can use atmospheric oxygen as the electrode active material. It is expected that the battery could be used for the electric vehicle which demands power sources with a high energy-density. This rechargeable battery needs bifunctional catalytic materials, which involve effective oxygen reduction/evolution at the air electrode at the discharge/charge process. In this study, a new bifunctional catalytic material for the air electrode has been developed using a conductive vanadate glass. Conductivity of vanadate glass, 20BaO·10Fe2O3·70V2O5, was reported to be easily tunable over a wide range (10-7 - 10-1 S･cm-1) when the local distortion of the glass skeleton was removed by means of the annealing [1]. Utilizing these characteristics, new catalytic materials have been prepared by adding MnO2 and NiO for the oxygen reduction and evolution, respectively.

20BaO·5MnO2·5NiO·70V2O5 glass was synthesized by melting the mixture composed of BaCO3, MnO2, NiO, and V2O5 at 1100 °C for 2 hours. The vanadate glass was annealed at 450 °C for various times (0, 30, 60, and 300 min.). Pulverized vanadate glass was utilized for the preparation of the air electrode by mixing the powder with 7.5 mass% of poly (tetrafluoroethylene) (PTFE), which was hot-pressed on a gas diffusion layer over a Ni metal mesh.

The electrode connected to a Cu wire was mounted onto the window of Teflon-made cell. 8M KOH aqueous solution and a Pt mesh were placed inside the Teflon cell as the electrolyte and the counter electrode, respectively. The temperature of the Teflon cell was held constant by soaking it into a water tank kept at 60 °C. Anodic and cathodic polarization measurements were carried out using a potentiostat. An Hg/HgO electrode was used as the reference electrode.

The electrical conductivity of the as-prepared vanadate glass was 5.4 × 10 -6 S cm-1 at RT. After the annealing at 450 oC for 300 min, it increased to 1.1 × 10 -2 S cm-1. Figure shows the anodic and cathodic polarization curves of 20BaO·5MnO2·5NiO·70V2O5 glass electrodes. The vanadate electrode showed an excellent bifunctional oxygen reduction/evolution activity, being comparable to that of the materials reported in the literature, like polycrystalline LaNiO3 [2]. This vanadate glass could be a highly potential candidate for the bifunctional catalytic material for the rechargeable metal-air battery.

References:

1) K. Matsuda, S. Kubuki, and T. Nishida, AIP Conf. Proc.
(msms2014)
1622, 3-7 (2014).

2) M. Yuasa, M. Nishida, T. Kida, N. Yamazoe, and K. Shimanoe, ECS
158, A605-A610 (2011).

Figure 1
The Scanning Kelvin Probe As a Non Destructive Evaluation Tool for Monitoring the Degradation of Urethane-Epoxy Coating Systems
Authors: Hansen Douglas C , Borth David
Published: February 2020

Performance degradation of urethane and epoxy coatings on high performance aircraft due to chemical reversion, while not visible on the surface, can be the result of changes in physical and chemical composition, leading to premature coating failure. Standard lifetime predictions fail to estimate the functional lifetime of urethane coatings on operational aircraft due to the wide variety of environmental factors and combinations of factors that trigger degradation at different rates. To better understand the role that environmental conditions play in the overall lifetime performance of these coatings, a non-destructive technique is necessary to quantitatively assess the degree of degradation/reversion that can occur. The scanning Kelvin probe (SKP) has demonstrated itself to be sensitive enough to detect changes in the alkyl chain lengths of polymers and their terminal groups as well as determine the interfacial diffusion of water through epoxy coatings as a function of the chemical structure and functional groups present within the coating. It has also demonstrated its capability to detect corrosion under coatings at the coating-metal interface. These capabilities make the use of the scanning Kelvin probe technique a compelling approach to detecting and characterizing the degradation behavior of multi-layer urethane and epoxy coating systems as well as any corrosion occurring at the coating-metal substrate interface. The objective of this effort is to develop a non-destructive evaluation technique for measurement and analysis of a multi-layer polyurethane/epoxy coating system subjected to elevated temperature and relative humidity (100 C, 100%RH) degradation conditions. Measurements of changes in the work function of non-exposed and exposed rain erosion coating (REC) system for various times at the elevated conditions have been made to correlate the degree of degradation within the coating system as determined by Raman/FTIR spectroscopy.
The Electrochemistry & Corrosion of Zn-Al-Mg Alloys: Quantifying the Contribution of Elemental Components and Individual Phases with Atomic Emission Spectroelectrochemistry
Authors: Ogle Kevin , Han Junsoo
Published: February 2020

In this work, we address the question of how various elements and various phases interact with each other during short term corrosion of complex alloys? For multi-phase alloys such as Zn-Al-Mg used here, predicting the corrosion behavior over a range of conditions is difficult because the solubility of the corrosion products of each element and the electrochemical activity of the alloy components differ markedly with one another as a function of pH. The electrochemistry of the Zn-Al-Mg system is further complicated by the distribution of the elements into a complex multiphase structure1.

To answer this question, we have applied the atomic emission spectroelectrochemistry (AESEC) technique. This allows us to measure directly the dissolution rate of each element during either a spontaneous, open circuit corrosion experiment (dissolution-corrosion profile), or to decompose the polarization curve into elemental currents (elemental polarization curve). Examples of the later are shown in the Figure below. We also use AC polarization so as to measure charge transfer resistance for each element around the open circuit potential.

The approach is to compare the dissolution-corrosion profile with the elemental polarization curve and the AC elemental polarization to see to what extent the corrosion rate of each element may be predicted from the polarization techniques. The question of microstructure is addressed directly by analyzing the role of phase structure on the dissolution of the coating. This is done by performing experiments on pure phases, intermetallic compounds, and a multiphase Zn-Al-Mg alloy galvanized steel coating. Nominally pure materials include: Zn, Al, and Mg; synthetic η-phase (Zn 0.7-Al), β-phase Al (Zn-22Al), and α-Al phase (Zn-68Al); and synthetic Zn2Mg intermetallic compound. The results are interpreted in terms of the mixed potential theory on an element by element basis, which allows prediction of the corrosion behavior of a system over a wide range of experimental conditions.

Fig.1. Elemental AESEC polarization curves of pure metals, Zn2Mg, and alloy coating in deaerated 10 mM NaCl solution at pH=10.1 at 25 °C.

 

References

1. T. Prosek, J. Hagstrom, D Persson, N. Fuertes, F. Lindberg, Ondrej Chocholaty, C. Taxén, J. Serák, D Thierry, Effect of microstructure of Zn-Al and Zn-Al-Mg model alloys on corrosion stability, Corrosion Science
110 (2016) 71-81.

Figure 1
Novel Corrosion Inhibitor Pigments Based on Benzotriazolium Cation Exchanged Resin
Authors: McMurray Hamilton Neil , Richards Calvin , Williams Geraint
Published: February 2020

A novel corrosion-inhibitor pigment is described which is prepared by the reaction of benzotriazole (BTA) with a crosslinked polystyrene sulfonic acid resin (Amberlite 120H). This pigment is completely insoluble in water and may readily be ground to sub-micron particle size. The formation reaction relies on the resin sulfonic acid functions (pKa -2.8) being significantly more acidic than BTA (pKa 1.1) so that proton transfer produces the benzotriazolium cation ( BTAH+) in an exchangeable form. The kinetics of BTA uptake from aqueous solution at 60oC are followed spectrophotometrically. It is thus shown that uptake is rapid (complete in minutes) and results in a BTAH+ exchange capacity of 143 milli-equivalents per100g. The BTAH+ pigment is evaluated as a corrosion inhibitor by dispersion in an ethanolic solution of polyvinylbutyral (PVB) which is then coated onto the cleaned surface of zinc-coated (hot dip galvanized) steel to produce a dry film thickness of ca. 30 microns. The BTAH+ pigmented PVB coatings thus prepared had BTAH+ pigment volume fractions of between zero and 0.2. A corrosive electrolyte solution (5% w/w aqueous NaCl) was introduced into a penetrative defect in the organic coating and the subsequent process corrosion-driven cathodic coating disbondment was followed using a scanning Kelvin probe (SKP) instrument in a “Stratmann type”experiment at 96% R.H. The SKP data show that increasing BTAH+ pigment volume fraction produces two well defined effects. First the potential of the intact (undisbonded) coated surface becomes depressed by up to 0.3 V versus the unpigmented case. Second the kinetics of cathodic disbondment are profoundly inhibited, becoming immeasurably slow for pigment volume fractions greater than 0.1. These results are interpreted in terms of two phenomena. First the “etching” of the zinc surface by the acidic resin with a consequent release of Zn2+ cations and neutral BTA. Second the inhibition of underfilm cathodic O2 reduction(COR) by surface adsorbed BTA or BTA-zinc complex. The inhibition of COR by BTA in solution is systematically investigated using a zinc rotating disk electrode (RDE) in conjunction with potentiodynamic polarization. The polarization data show that, although BTA profoundly inhibits COR on zinc, BTA is actually a mixed inhibitor and inhibits both anodic zinc dissolution and the COR.
Computational and Experimental Analyses of Galvanic Corrosion of AA7075-T6 Induced By Dissimilar Metal Fasteners and Mitigated By Sol-Gel Coatings
Authors: Tattersall Colin
Published: February 2020

In modern aircraft, there is a need to protect aluminum structures from galvanic corrosion due to dissimilar metals used in complex aerospace structures. Galvanic corrosion between corrosion resistant fasteners (e.g., stainless steel or titanium alloys) and aluminum alloy structures represent a recurring problem. One means of mitigating such attack is via the application of surface treatments to the fasteners designed to limit their cathodic current density. Detailed measurements and modeling of these effects are important to optimization of the surface treatment and estimates of the level of improvement likely to be achieved. The present work combines experimental measurements of galvanic corrosion damage and computational modeling of galvanic current distributions. The goal is quantitatively connect observations of decreased galvanic corrosion damage on AA7075-T6 coupons due to the presence of stainless steel fasteners under thin electrolyte films as would be present in aerospace service. In particular, sol-gel surface treatments were applied to stainless steel and titanium alloy fasteners which were then placed in AA7075-T6 panels before exposure to salt spray testing. Experimental analyses of corrosion damage were performed using white light interferometry generated depth profiles. These data were used to create data for total volume mass loss (TVML). Computational modeling of galvanic current distributions was performed using a commercial FEM package for thin electrolyte film conditions with experimentally-derived electrochemical kinetics as boundary conditions. The polarization curves used and the current distributions for a 0.1 mm electrolyte layer are shown in Figure 1. Integration of the anodic current densities on the AA7075 over the surface produces a corrosion damage metric, the total anodic current (TAC). The effects of sample geometry, including spacing between fasteners and their location relative to the edges of the sample, as well as water layer thickness and solution concentration on the TAC will be reported. The TVML and TAC can be correlated to one another and to total measured mass loss via Faraday’s Law. Comparisons between the TVML and the TAC will be discussed in detail. Of particular importance will be analyses of the effective throwing power of the fasteners as a function of fastener material and the presence or absence of sol gel surface treatments.

Figure 1: (a) Polarization curves in 0.6 M NaCl of the materials of interest. (b) False color plot of anodic (positive) and cathodic (negative) current distribution (A/m2) for a 0.1 mm electrolyte layer of 0.6 M NaCl

Acknowledgements: The financial support of the Office of Naval Research through Contract # N68335-16-C-0121 (William Nickerson, PM) via Luna Innovations (Adam Goff) is gratefully acknowledged.

Figure 1
(Keynote) Leaching of Inhibitor Particles Followed By 4D X-Ray Tomography
Authors: Liu Yanwen , Zhou Xiaorong , Gibbon Simon R , Graham Derek , Burnett Tim , Lyon Stuart B
Published: February 2020

Coil-coated zinc-alloy steel is a widely used commodity from white-goods manufacture to architectural claddings. Corrosion protection is generally provided to the substrate, and to any exposed cut edges, by a primer coating using an inhibitive pigme that, conventionally, consists of strontium chromate. However, chromate-free formulations containing phosphate-type pigments are now preferred. A common primer formulation contains strontium aluminium polyphosphate (SAPP) and, in previous work, it has been determined that the solubility of such inhibitors has two conflicting effects. On the one hand, free ions released from the inhibitor migrate to the metal substrate and reduce/inhibit corrosion by formation of a thin precipitated salt film containing zinc, phosphorous and oxygen. On the other hand, the dissolution of the inhibitor results in an increased porosity in the coatings, consequently creating more obvious pathways for aggressive species to reach the metal surface and for the transport of corrosion products. Further, insoluble corrosion products, or precipitated inhibitive salt films, in some cases appear to fill the cavities left by the dissolution of the SAPP inhibitor and, consequently, provide potentially improved barrier protection to the metal substrate.

In the present study the leaching behaviour of nano- to micron scale corrosion inhibitor pigment, of strontium aluminium polyphosphate from a polymer coating was followed over 14 days by 4D x-ray nano tomography. It is apparent that SAPP is not a homogeneous material and contains both strontium-rich components, which leach extensively, and aluminium-rich components, which are more resistant to dissolution. Through the investigation of individual pigment particles and their 3D spatial connections in the polymer matrix, the transport routes of the leaching particles in the polymer matrix may be explored.

The figure shows the evolution of an organic coating pigmented with SAPP corrosion inhibitor over the course of immersion in sodium chloride solution: (a) before immersion; (b) after immersion for 1 day; (c) after immersion for 7 days; (d) after immersion for 14 days. The oval regions highlight the dissolution of strontium-rich particles while the square region highlight the aluminium-rich components of the SAP.

Figure 1
Impedance Analysis of Constant-Phase-Element Behavior of Heavy-Duty Coating for Evaluating Its Aging Degradation
Authors: Tokutake Koya , Nishi Haruki , Okazaki Shinji
Published: February 2020

Being a resource-poor country, Japan needs oil storage steel tanks to store oil imported from overseas. In general, an electrolyte solution accumulates in bottoms of tanks because the oil contains water, chloride ions, sulfate ions and oxygen. Therefore, corrosion occuring in the inner surfaces of the bottom plates is a serious problem. Presently, the inner surfaces are usually coated with a heavy-duty coating to inhibit the corrosion. Since the heavy-duty coating has exceptional durability, it is often difficult to monitor the aging degradation by a laboratory immersion test, and the long-term degradation behavior is unclear. In a present work, the impedance characteristics of the heavy-duty coating used for a long period is analyzed to develop an evaluation method for the degradation of the heavy-duty coating applied to large steel structures by focusing on the recent studies in terms of the CPE.

Acknowledgement: This research was performed with financial support from Japan Oil, Gas and Metals National Corporation.