bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mixtures of Ionic Liquid and Organic Electrolyte with Improved Safety and Electrochemical Performance with Nanostructured Silicon-Anode for Li-Ion Batteries
Authors: Pandey Gaind P. , Meda Lamartine , Li Jun 
Published: February 2020

The present rechargeable lithium-ion battery systems commonly use small amount of electrolytes based on suitable lithium salts (generally LiPF6) and organic solvents (generally alkylcarbonates, such as EC, DMC), which represent a major concern for device safety due to the flammable and volatile nature of these organic liquids. The use of these organic carbonates electrolytes allows the realization of high-performance batteries, but due to its flammability, their use also poses serious safety risks and strongly reduces the battery operative temperature range. Therefore, alternative electrolytes have been proposed and tested in the last decade [1].
Ionic liquids doped with a lithium salt are alternative electrolytes for lithium-ion batteries that offer some advantages compared to organic carbonates based liquid electrolytes. Ionic liquids display a low vapor pressure which leads to nonflammability. The main drawback of ionic liquid-based electrolytes is the low lithium-ion conductivity due to relatively high viscosity of ionic liquids. A lot of research has been devoted to developing ionic liquids with low viscosity. However, so far, these ionic liquids could be obtained only at the expense of lower thermal and/or electrochemical stability. In recent years, mixtures of organic carbonates-based electrolytes and ionic liquids have been proposed as a solution to overcome the lithium-ion transport limitations of ionic liquid-based electrolytes while improving safety due to a lower flammability than that of organic carbonates electrolytes [1, 2].
Herein, we report the results of physical-chemical and electrochemical investigations performed on mixed electrolytes based on an ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI), and organic electrolytes (LiTFSI in EC/DMC) with nanostructured silicon-anode for lithium-ion batteries. The ionic conductivity, lithium-ion transference number, viscosity and electrochemical stability windows of all different ionic liquid content mixtures were investigated and compared with carbonates-based electrolyte. The specific capacity and cycling stability of the nanostructured silicon-anode were investigated at different C-rates at room temperature. A reversible capacity of 3480 mAh g-1 (of Si) at C/10 and 1600 mAh g-1 at 5C is obtained with cells having electrolyte mixture with a composition of 1:1. This study indicates that safety and electrochemical performance of the Si-anode for Li-ion battery can be improved by using mixed ionic liquid and carbonates-based electrolytes.
[1] A. Guerfi, M. Dontigny, P. Charest, M. Petitclerc, M. Lagacé, A. Vijh, K. Zaghib, J. Power Sources 195 (2010) 845-852.
[2] R.-S. Kühnel and A. Balducci, J. Phys. Chem. C 118 (2014) 5742-5748.
Effect of Hydroxyapatite Coatings on Photocatalytic Characteristics of Titanium Dioxide Photoanode
Authors: Nay Wunn Htoo , Morita Motoaki , Motoda Shinichi 
Published: February 2020

The photocatalytic n-type semiconductor characteristics of titanium dioxide (TiO2) has been under study for decades. We have studied the effect of dye sensitizing on TiO2 electrode with seawater as the electrolyte. In that study, we found that only the hydroxyapatite (HAp) coating used for the purpose to increase the binding ability between dye and TiO2 improved the capability of TiO2 electrode. However, the mechanism of HAp coating is unclear. In order to make it clear and to improve the effect of HAp coating on TiO2 electrode, this study is conducted by preparing different types of HAp paste for coating on TiO2 electrode.
Screen printing method was used for TiO2 layer and both manual and screen printings were used for HAp (Ca10(PO4)6(OH)2) coating for comparison. Type 329J4L stainless steel was used as a substrate for TiO2 electrode. The surface of the substrate was cleaned with ultrasonic cleaner and then the surface was passivated with HNO3 solution for 30 minutes. Double layers of TiO2 were screen printed on the substrate. The first layer was screen printed and heat treated at 150 ºC for 60 minutes. The second one after printed was heat treated at 550 ºC for 30 minutes. HAp was coated on TiO2 doubled layer. HAp paste was heat treated after printed. HAp paste was prepared from HAp powder. The powder was mixed with carboxymethyl cellulose (CMC) in various ratios. Water and alcohols are added to the mixture and well stirred to be a paste. Different types of HAp paste were prepared by changing the ratios of the components of the paste. The finishing was performed to get the electrodes ready for measurements in artificial seawater.
The potential measurement, polarization and power density measurements against platinum counter electrode were performed by a potentiostat in dark and irradiated conditions. The irradiation used for the experiments is a Xenon lamp with 150 W and calibrated wavelength range from 250 nm to 800 nm. The lamp was calibrated so that the light intensity produced became approximately 10.5 mW/cm2. The surfaces of the electrodes before and after measurement were analysed and compared by Scanning Electron Microscope (SEM). The study is in progress and the preliminary showed that screen printing of HAp on TiO2 electrode showed higher photopotentials than manual printing or without printing. The variations in HAp paste constituents also affected the performance of TiO2 electrodes.
Design of Preferentially Faceted Zinc to Improve the Rechargeability of Alkaline Batteries
Authors: Faegh Ehsan , Ng Benjamin , Hayman Dillon , Mustain William E. 
Published: February 2020

Rechargeable Zinc-based batteries have attracted a growing interest due to their intrinsic high safety as well as the low environmental impact and low cost of Zinc. However, there still exists some major obstacles in achieving these low cost secondary cells, including shape change during repeated charge/discharge (dendrite formation) and limited reversibility of the Zinc electrodes. Traditional Zinc anodes are formed from large, polycrystalline particles with limited control over the morphology. Many studies have looked to improve morphology control of Zinc through the design of Zinc nanostructures 1, 2, but the future implementation of these nanomaterials is hindered by the high rate of corrosion for Zinc nanostructures 3, 4 as well as the expense and scalability of manufacturing such nanostructures. Therefore, there is a need to develop a scalable synthesis method that allows for the creation of large monocrystalline particles with controlled shape.
In this work, we report a facile electrolytic method to synthesize micron-sized preferentially faceted, hexagonal-shaped Zinc particles. Using a three-electrode electrochemical cell, the charge and discharge behavior of these Zinc particles were studied in alkaline (6M KOH) and mildly acidic (1M ZnSO4) aqueous electrolytes. It was confirmed that the dendrites form during cycling the Zinc particles in KOH electrolytes, however, using ZnSO4 electrolytes no dendrite formation was observed, and the particles were able to retain their hexagonal structures ever after cycling for than 100 times at 1C.

References

M. Chamoun, B. J. Hertzberg, T. Gupta, D. Davies, S. Bhadra, B. Van Tassell, C. Erdonmez, and D. A. Steingart, NPG Asia Materials,
7 (4), e178 (2015).

T.-H. Wu, Y. Zhang, Z. D. Althouse, and N. Liu, Materials Today Nano, 100032 (2019).

E. Faegh, T. Omasta, M. Hull, S. Ferrin, S. Shrestha, J. Lechman, D. Bolintineanu, M. Zuraw, and W. E. Mustain, Journal of The Electrochemical Society,
165 (11), A2528-A2535 (2018).

Y.-D. Cho and G. T.-K. Fey, Journal of Power Sources,
184 (2), 610-616 (2008).
Anodic Oxide Growth on Heat-Treated Titanium
Authors: Tsuchiya Hiroaki , Kamimura Yuka , Fujimoto Shinji 
Published: February 2020

It has been reported that self-organized nanotubular oxide layers are formed on various metals and alloys by anodization in fluoride containing electrolytes. In particular, the nanotubular structure of TiO2 has been extensively studied due to a wide range of application of TiO2. To tune the properties of the layers, the optimization of anodization condition has been carried out. However, in such trials, the chemical aspects of anodization condition have been mainly focused, that is, only few works has reported the metallurgical aspects of the condition. In the present work, we examined the effects of heat-treatment on anodization behavior and resulting morphology of the TiO2 architecture.
Specimens were cut from pure titanium sheets (purity; 99.5 %). The specimens were encapsulated into a silica quartz tube where the vacuum level was controlled less than approximately 2x10-5 torr. The specimens in the silica tube were heat-treated under several conditions. After the heat-treatments, the surface of the specimens was ground with SiC abrasive papers and then mirror-finished with diamond pates and colloidal silica suspension. The specimens were anodized at 50 V in a mixture of ethylene glycol, water and ammonium fluoride. After the anodization, the surface and cross-sectional morphology of resulting oxide layers was observed.
Under an optimized heat-treatment condition examined, the specimen consisting of large grains in millimeter range was obtained. The anodization of the specimen revealed that its current behavior was similar to that obtained on as-received specimen. In addition, the obtained structure of anodic oxide layer on the heat-treated specimen was also similar to that on as-received specimen, that is, nanotubular structure was obtained. However, the thickness of the nanotubular oxide layer and the ordering of nanotubes were clearly different. Higher thickness of nanotubular oxide layer was obtained and improved ordering of nanotubes was found on the heat-treated specimen. These results indicate that the substrate property could affect not only the growth but also arrangement of nanotubes.
Corrosion of Directed Energy Deposited Cantor Alloy in Molten KNO3-NaNO3 for Solar Thermal Applications
Authors: Moon Jeremy , Summers Kodi , Melia Michael Anthony , Kustas Andrew , Argibay Nicolas , Schindelholz Eric John , Chidambaram Dev 
Published: February 2020

High entropy alloys (HEA) with 4-5 component elements are being considered for various applications including nuclear and solar thermal energy generation due to desirable mechanical properties and corrosion resistance.
Advanced heat transfer systems in both nuclear and solar thermal energy generation are being designed to utilize molten salts as the working fluid, allowing for a significant increase in hot-leg temperatures leading to increased efficiency. The use of additively manufactured HEAs may be beneficial to these systems but corrosion properties of HEAs have not yet been established for many of the common molten salt systems. Additionally, the unique microstructure of HEA components produced via additive manufacturing can potentially alter the corrosion properties of the component relative to a cast or forged microstructure. This study will focus on CoCrFeMnNi HEA Cantor alloy prepared via an additive manufacturing pathway using directed energy deposition (DED); this method will allow for the development of complex geometries not available through traditional manufacturing methods.
To understand the corrosion of additively-manufactured HEAs, a sample of DED-manufactured Cantor alloy was exposed to a 40/60 weight percent mixture of molten KNO3-NaNO­3 at 500 °C. This environment is relevant to solar thermal power plants. Accelerated corrosion testing using potentiodynamic polarization was carried out. Also, the sample subsequently underwent 50 hours of exposure to the molten salt. The sample surface was analyzed with x-ray diffraction, x-ray photoelectron spectroscopy, and focused ion beam milling coupled with scanning electron microscopy/energy dispersive spectroscopy. The molten salt electrolyte was analyzed post-exposure via inductively-coupled plasma – optical emission spectroscopy. Cantor alloy exposed to this nitrate salt mixture developed an oxide film with small, densely packed, vertically oriented fin-shaped grains and an inhomogeneous composition profile through its depth. The results of these studies will be discussed.
Acknowledgments: The authors thank Zachary Karmiol, research scientist at Materials Characterization Nevada, for technical input. One of the authors, JM, acknowledges the Graduate Research Fellowship from the US National Science Foundation. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1447692.
On the Development of a Flow-Type Electrochemical Microcell
Authors: Summers Kodi , Kaehr Bryan J. , Schindelholz Eric John , Chidambaram Dev 
Published: February 2020

Localized corrosion is one of the most challenging and important fields in corrosion science. While there are a number of methods for studying corrosion at small scales, a majority of these methods involves immersion of a sample into an environment of interest, exposing them for prescribed amount of time, and then analyzing the sample’s surface post-exposure. Methods that have been studied include (i) the use of electrochemical techniques during immersion to understand transient processes that initiate and those that propagate localized corrosion behavior such as scanning reference electrode technique (SRET), and (ii) using electrochemical microcells or scanning droplet cells to perform electrochemical analysis of sample surfaces without the need to immerse an entire sample into an environment. The downside of these techniques is either that the entire sample must be sacrificed for the analysis or that the analysis area is still too large to truly isolate localized corrosion processes. In this study, we demonstrate a novel approach to the development of a flow-type electrochemical microcell that provides the necessary resolution to study localized corrosion while being completely customizable. Additionally, results on various samples will be presented showing the applicability of the system as well as verification of performance.
Acknowledgement: This work was performed under the auspices of the US Nuclear Regulatory Commission (NRC) under contract NRC-HQ-84-16-G-0033. Ms. Nancy Hebron-Isreal serves as the program manager.
Explanation of the Electrochemical Behavior of Salt Film in Pit Growth
Authors: Li Tianshu , Scully John R. , Frankel Gerald S. 
Published: February 2020

A unifying framework has recently been developed to describe the critical conditions for pit growth stability and salt film formation 1-3. It was shown that a salt film is not required for pit stabilization; it is just a consequence of a pit achieving diffusion-controlled growth. A salt film can form on the surface of both metastable and stable pits when the maximum pit dissolution current density, i
diss,max, exceeds the diffusion-limited current density, i
lim.
In this work, the unifying framework is further expanded to establish a mathematical model describing the electrochemical behavior of salt film after it precipitates, i.e. the situation when i
diss,max > i
lim. It can be mathematically shown that the main function of a salt film during diffusion-controlled pit growth is to accommodate the extra potential of (E
max - E
sat) by regulating its thickness to adjust the actual potential at the pit surface to E
sat and thus restricting the anodic dissolution current density at the diffusion-limited value 4. Therefore, the salt film will respond to any changes of the applied potential, temperature, pit depth, and perforation radius of the pit cover.
This new model can explain the current peak observed during the downward potential scan of a 1D pit at the transition point from diffusion-controlled region to charge-transfer-controlled region. According to this new model, the current peak results from the supersaturation generated by thinning of the salt film during the downward scan. The model predicts that the amplitude of the current peak decreases with decreasing scan rate, which is in agreement with the experimental results from 1D artificial electrode, providing strong support for the validity of the new model.

Acknowledgments: This work was supported as part of the Center for Performance and Design of Nuclear Waste Forms and Containers, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0016584.
Reference

G. S. Frankel, T. Li and J. R. Scully, Journal of the Electrochemical Society
164, C180-C181 (2017).

T. Li, J. R. Scully and G. S. Frankel, Journal of The Electrochemical Society
165, C484-C491 (2018).

T. Li, J. R. Scully and G. S. Frankel, Journal of The Electrochemical Society
165, C762-C770 (2018).

T. Li, J. R. Scully and G. S. Frankel, Journal of The Electrochemical Society
166, C115-C124 (2019).
Under Deposit Corrosion in Steam Generators: Towards Understanding Critical Deposit Thresholds
Authors: Ramesh Abitha , Puolamaa Milla E , Laycock Nick , Barnes Andrew , Thyagarajan Aarthi , Abdullah Aboubakr M , Stitt Camilla , Ryan Mary P. 
Published: February 2020

Most significant industrial facilities operate large steam systems, including multiple steam generators. The steam produced may be used for power generation by steam turbines or for heating various equipment items and is usually critical to the overall operation of the plant. Each steam generator will typically contain hundreds of carbon steel tubes: the failure of such tubes by unpredicted corrosion represents a common cause of plant downtime, significant lost production, and an ongoing safety risk.
The mechanism of UDC in these systems is not well-understood, and this is in part because of the experimental challenges of studying such systems [1-3]. However, some clear parametric observations have been made and it is now established that very low (ppb) levels of dissolved ferrous ions and micro-scale particles of magnetite are produced by flow-assisted corrosion in the steam generator feed-water systems, and that these are then deposited on to the heat transfer surfaces. Together with the presence of only trace (ppb) levels of bulk chloride contamination, these deposits can lead to extraordinarily rapid corrosion. Characteristic features of the damaged material include: the porous structure of the deposit layer; the presence of high local chloride concentrations within the deposits; and formation of a complex ‘multi-duplex’ layer of corrosion product that exhibits approximately linear growth kinetics.
According to EPRI guidelines [4], 35 mg.cm-2 represents a critical threshold for deposit thickness after which interventional maintenance should be initiated. This nominal thickness is not based on mechanistic understanding and is often achieved in boilers within only a few years of operation, resulting in the need for expensive and time-consuming chemical cleaning to remove the deposits. Hence, it is necessary to better understand the various stages in the formation of these layers to improve prediction of UDC and help reduce conservatism in maintenance without compromising on safety.
In this presentation, we will present a study of field-retrieved samples that were examined with optical and electron microscopy techniques, coupled with phase and chemical analyses. This will be compared with model experiments where deposits are formed under laboratory-controlled conditions [1], including both new and literature data. We will discuss these data in terms of a model for UDC in steam generators, with emphasis on the critical deposit thickness and the particular role of chloride in the formation of the characteristic multi-duplex scales.

References

Robertson, J. and Forrest, J.E., 1991, Corrosion Science, 32(5/6), 521-540.

Howell, A.G., 2006, NACE – 06458, NACE international publication.

Dooley, R.B. and Bursik, A., 2010, Boiler and HRSG tube failures - Hydrogen Damage, 12(2), 122-127.

Dooley, R.B., 2005, EPRI Technical Report, 1-154.
Finite Element Modelling of Microelectrode Arrays of Mg and AA2024 Galvanic Couple
Authors: Moraes Carolina Vicente , Kelly Robert G. 
Published: February 2020

Aerospace aluminum alloys, such as AA2024-T3, are susceptible to microgalvanic corrosion and pitting due to its heterogeneous microstructure. Thus, they require additional corrosion protection methods. Magnesium rich primer coatings (MgRP) have emerged as an effective alternative to highly toxic chromate-based coatings. MgRP systems consist of an organic resin loaded with Mg pigment. The organic resin provides barrier protection, while metallic Mg pigment serves as a sacrificial anode by galvanic coupling with more noble Al alloy. The distance over which an active corrosion system can protect a defect exposing a metal surface is named galvanic throwing power and it is an important parameter used to evaluate the effectiveness of this type of protection method. Microelectrode array (MEA) is a technique commonly used to determine the galvanic throwing power. In this technique, wires of the metals of interest are mounted in a non-conductive matrix and the galvanic current distribution over the wires is measured. The wire diameter and the distance between the wires are important factors that affect the accuracy of MEA. While thin wires can provide finer spatial resolution, the experimental setup is challenging, and edge effects can decrease the representativeness of the measurement.
Finite element analysis (FEA) is a tool used to predict both spatial and temporal potential and current distributions in electrochemical systems related to metal dissolution and cathodic reactions. FEA also can be used as an experimental design tool. In this work, FEA was used to assess important parameters and predict an optimal combination of wire diameters and distance between wires that result in higher accuracy of MEA.
COMSOL Multiphysics (ver.5.4) was used to perform the finite element simulations. Potentiodynamic polarization scans of AA2024 and pure Mg immersed in 0.9 M NaCl solution were performed to generate E - i curves that were used as the electrochemical boundary conditions. Laplace equation was used to describe the current distribution that resulted from the galvanic coupling. The effect of the spacing between the wires and their diameters on the current distribution was studied. The results were compared to a reference solid plate configuration, where the two metals were in electrical contact.