bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement in Cycling Performance of Rechargeable Metal Hydride/Air Laminate Cell
Authors: Fukumoto Tatsuya , Kawaguchi Kenji , Morimitsu Masatsugu 
Published: February 2020

A metal hydride (MH)/air secondary battery is one of the next generation energy storage devices, since a high energy density and a high power density are expected from its unique property that the active mass of the positive electrode is oxygen in air. We have developed this type of battery and demonstrated that a non-packaged cell fabricated using PTFE container has about 900 Wh/L [1] and a laminate cell using polyethylene film about 772 Wh/L [2], which are beyond the energy density of lithium ion secondary batteries. However, the laminate cell also indicated some issues on the structure and components of the cell, causing the electrolyte’s leakage and a poor cycleability. This work was done to improve the charge-discharge performance of the MH/air laminate cell, especially the cycling performance, and evaluated the charge-discharge behaviors of the cell obtained with some modification in the process and materials.
The laminate cell consisted of an MH electrode (23 mm x 23 mm), an air electrode (23 x 23 mm), and a separator with 6 mol/L KOH solution between the electrodes, which were thermally sealed and packed in polyethylene (PE) film having an open area (13 x 13 mm) on the air electrode. All the components were the same as those used in our previous work [1]. We examined the design, size, and thickness of PE film to improve the adhesion to the electrode and between PE films and to inhibit the leakage of the alkaline solution. A water repellent film attached to the air electrode to prevent the flooding of the solution was also modified to suppress the increase in internal pressure by oxygen generated during charge. The cell was operated with constant current (0.05 C) at room temperature in a desiccator, and the cell voltages during charge and discharge were measured, in which charge was limited for 2 hours and the cut-off voltage of discharge was 0.5 V.
Some modifications in the structure and components of the laminate cell, e.g., the change in the electrode’s tab from Ni ribbon to Ni mesh and the optimization on the thickness of PE film and the thermal bonding conditions such as heating temperature and time, resulted in no leakage of the electrolyte during charge-discharge cycles and no expansion of the laminate package by oxygen, and the cycling performance was significantly enhanced compared to our previous cell [2]. The cell presented very stable charge and discharge voltages for 20 cycles and the current efficiency was more than 90 %. More detailed results will be shown in this paper.

This work was financially supported by “Advanced Low Carbon Technology Research and Development Program (ALCA)” of Japan Science and Technology Agency (JST). The authors acknowledge FDK Corporation for supplying the MH negative electrode.

Reference
[1] T. Gejo, K. Kawaguchi, M. Morimitsu, 2017 TMS Annual Meeting & Exhibition, Pan American Materials Congress, San Diego, USA (2017).
[2] S. Kino, M. Morimitsu, The 232th ECS Meeting, Abs#104870, Washington, D. C., USA (2015).
Effects of Severe Plastic Deformation and Interstitial Carbon on Corrosion Resistance of Steel
Authors: Komura Tomoki , Muto Izumi , Sugawara Yu 
Published: February 2020

For the improvement of mechanical properties of steels, nanocrystallization is a center of interest. Nanocrystallization greatly influences on the mechanical properties such as tensile strength, ductility, and wear resistance. Severe plastic deformation (SPD) is one of the effective methods to generate the nanocrystalline structure. It was reported that nanocrystallization also affects corrosion behavior of steels. When the grain size of stainless steels is less than 1 μm, it would appear that the grain boundaries act as barriers against the growth of pitting corrosion1). Interstitial carbon atoms also affect the corrosion behavior2). In this study, the SPD layers were fabricated on Fe plates by ball-milling, and electrochemical measurements were conducted to investigate the corrosion behavior of the SPD layers.
Planetary ball-milling was applied to fabricate the SPD layers on Fe and stainless steel plates. The Fe and type 304 stainless steel plates were polished by SiC paper through a 1500 grid and put into a stainless steel pot with Fe powders, and mechanical alloying of Fe and C powders was accomplished. Grinding balls were made of stainless steel. In the milling process, the SPD layers of Fe-C alloy were fabricated on the Fe and stainless steel plates. To investigate the effect of the carbon concentration, the amount of the carbon powders put into the pot was changed.
Potentiodynamic anodic polarization curves were measured in deaerated H3BO3-Na2B4O7-1 mM NaCl solution (pH 8.0) at 298 K to elucidate the influence of the SPD and the carbon concentration on the corrosion resistance of the Fe-C steels. With the exception of the electrode area (ca. 5 mm × 5 mm), the surfaces of the specimen were coated with an epoxy resin and paraffin. The measurements were performed in a conventional three electrode cell. The reference electrode was Ag/AgCl (3.33 M KCl) and the counter electrode was a Pt plate.
The results of potentiodynamic anodic polarization for the SPD layers on the Fe plates are shown in Fig. 1. In the case of pure Fe, the increase of the anodic current density at ca. -0.5 V was due to the anodic oxidation and/or dissolution of Fe. In the potential range of -0.3 to 0 V, the current density decreased by passivation. And then, the current density drastically increased. This appeared to be attributed to localized corrosion. On the other hand, at around -0.5 V, the current densities for Fe-0.1mass%C and Fe-0.5mass%C were higher than that of pure Fe. However, the passivation current density of Fe-0.5mass%C specimen was the lowest. Therefore, the increase of carbon concentration possibly causes the improvement of corrosion resistance.
References
1. A. Chiba, I. Muto, Y. Sugawara, and N. Hara, J. Electrochem. Soc., 159, C345 (2012).
2. A.Chiba, S. Shibukawa, I. Muto, T. Doi, K. Kawano, Y. Sugawara, and N. Hara, J. Electrochem. Soc., 162, C278 (2015).

Figure 1
Change in pH and Chloride Concentration inside Crevice of Stainless Steels
Authors: Matsumura Kengo , Muto Izumi , Sugawara Yu 
Published: February 2020

Stainless steels sometimes suffer from crevice corrosion in chloride environments. The pH value and Cl- concentration are important factors in the initiation and growth of crevice corrosion. Nishimoto et.al.[1] fabricated a glass plate with a sol-gel SiO2 sensing layer, which contains a pH indicator and a Cl- sensitive florescent dye, and the pH and Cl- distributions in the crevice solution for stainless steel were visualized simultaneously.
The specimens used in this study were cut from a Type 430 stainless steel sheet (0.035%C, 0.20%Si, 0.38%Mn, 0.019%P, 0.005%S, 0.19%Ni, 15.9%Cr in mass%). The specimens were heat-treated at 1123 K for 600 s and water-cooled. The size of the specimen was 4 mm×3 mm×20 mm. The specimen surfaces were polished by a 1 μm diamond past.
To fabricate the sensing plate for the simulations measurements of pH and Cl- concentration, Terbium-dipicolinic acid complex (Tb-DPA) and quinine sulfate as the fluorescent dyes were chosen. Tb-DPA was used as the sensing dye for the pH measurements, and quinine sulfate was used to measure the Cl- concentration. Tb-DPA was formed by mixing Tb­­2(SO4)3 and dipicolinic acid. A sol-gel method was used to make the sensing layer, which contained two fluorescent dyes, onto one side of a quartz glass plate.
Figure 1 shows the illustration of a crevice corrosion test cell. In crevice corrosion tests, the crevice was formed between the sensing plate and specimen. Potentiostatic polarization was performed at 0.15 V (vs. Ag/AgCl, 3.33 M KCl) in 10 mM NaCl (pH 3.0). During crevice corrosion tests, the surface images of the specimen were taken under UV irradiation, and pH and Cl- values were calculated from the fluorescence images. The details were described in the literature. [1]
Figure 2 shows the surface appearance and the images of pH and Cl- distributions at the initiation point of the crevice corrosion at 1500 s. The pH and Cl- were calculated by the brightness of fluorescence images. A pit was initiated inside the crevice. Before the initiation of crevice corrosion, it was elucidated that the pH at the initiation point of gradually decreased with time, and that the Cl- concentration increased with time. On the basis of time variations of the pH and Cl- concentration, the initiation and growth mechanims of the crevice corrosion of stainales steels were determiend.
References;

Nishimoto, J. Ogawa, I. Muto, Y. Sugawara, N. Hara: Corros. Sci.,
106, 298-302(2016)

Figure 1
Under-Deposit Corrosion (UDC): The Hidden Cause of Major Asset Failures in the Oil and Gas Industry
Authors: Shamso Ahmed Nabil , Abdullah Aboubakr Moustafa , Laycock Nick , Ryan Mary P 
Published: February 2020

With the continued need for fossil fuels, even as we enter energy transitions, the extraction of oil and gas from significantly abundant sour fields is increasing globally. Sour i,e, H2S –containing gas environments present several challenges to system integrity, including an accelerated rate of localized corrosion, and potential catastrophic premature failures in fluid handling equipment. This creates a risk to asset integrity, leading to financial losses, and significant risk to both human health and the environment. A major problem in sour systems is ‘underdeposit corrosion (UDC)’ which is a type of extremely rapid, localized attack observed under deposits (in this case typically iron-sulfides); it is extremely difficult to both predict and monitor. The mechanism of both iron sulfide formation and UDC in pipeline is not fully understood: the complex nature of iron sulfides along with the dynamic changes of their physical and chemical properties during the corrosion process entails that multiscale correlative investigations are needed.
1-dimensional artificial pit experiments are developed in order to study localised corrosion with the use of multi-electrode arrays; this allows high-throughput measurements such that different variables can be studied simultaneously. The artificial pit acts as an anode in a three-electrode electrochemical cell, simulating an actively dissolving pit, but with reduced dimensionality that allows quantitative extraction of kinetic data as a function of the various system parameters- essentially the deposit physical and chemical properties. Data on the role of deposit chemistry and morphology on the electrochemical dissolution behaviour are presented, and discussed in terms of a transport-controlled model for pit propagation. Complementary planar (2D) surface experiments were performed under deposits; using this blended approach, both general and localized corrosion can be assessed and related to provide a comprehensive understanding of the overall performance of steel under deposits. The dynamic physicochemical variations (surface morphology and chemical composition) in both metal and deposit are related to the electrochemical findings to explain the metal-deposit interdependent physicochemical interactions.
The findings of the study paved the way towards innovating experimental methods for example the use of micro-pH electrodes to provide real-time data on the chemistry inside actively dissolving pits under representative deposits. This study provides insights into the different scenarios of UDC phenomenon and potential protocols to develop monitoring probes for industrial application.
Fast 2D Diffusion in Nanocrystalline RbSn2F5 as Seen By Impedance and 19f NMR Spectroscopy
Authors: Gombotz Maria , Lunghammer Sarah , Breuer Stefan , Preishuber-Pflügl Florian , Wilkening Martin 
Published: February 2020

The functionality of sensors or batteries relies in many cases on mobile ions such as Li+, Na+, O2- or F-, which are subjected to rapid self-diffusion processes. The dynamic parameters as well as the shape of the underlying motion correlation function depend on the dimensionality of the diffusion pathways. Model compounds help to unambiguously proof the concepts and models developed to describe low dimensional diffusion.[1-3] The pseudo-binary fluoride RbSn2F5 with trigonal symmetry constitutes such a model substance.
Here, we present a new mechanochemical route to synthesise nanocrystalline RbSn2F5 via a one-pot reaction in a planetary mill. Soft annealing transforms the as prepared product into microcrystalline RbSn2F5. We used X-ray diffraction, thermal analyses and high-resolution 87Rb, 19F , and 119Sn NMR spectroscopy to characterize structure and ion dynamics in detail. In particular, we took advantage of AC impedance spectroscopy and time-domain NMR measurements to record diffusion-induced spin-lattice-relaxation rates in both the laboratory and rotating frame of reference to monitor long-range as well as short-ranged F anion transport processes in RbSn2F5. It turned out that only an NMR spectral density function developed for 2D diffusion yields an activation energy being in accordance with that derived from conductivity measurements. Our results confirm Richards[4,5] semi-empirical NMR relaxation model for 2D uncorrelated jump diffusion, not only for microcrystalline RbSn2F5 but also for the nanocrystalline, mechanosynthesized sample.
Financial support by the Austrian Federal Ministry for Science, Research and Economy as well as the Christian-Doppler Forschungsgesellschaft is highly appreciated.
References
[1] M. Wilkening, W. Küchler, and P. Heitjans, Phys.
Rev. Lett.
97, 065901 (2006).
[2] A. F. McDowell, C. F. Mendelsohn, M. S. Conradi, R. C. Bowman, and A. J. Maeland, Phys. Rev. B.

51, 6336 (1995).
[3] V. Epp and M. Wilkening, Phys. Rev. B
82, 020301 (2010).
[4] P. M. Richards, Solid State Commun.
25, 1019 (1978).
[5] P. M. Richards. In Topics in Current Physics (Ed. M. B. Salamon), Band 15, Springer, Berlin (1979).
Atomistic State of Absorbed Hydrogen in Electrodeposited Platinum Films
Authors: Kinoshita Takeshi , Yokoyama Ayano , Matsumoto Ayumu , Fukumuro Naoki , Yae Shinji 
Published: February 2020

Hydrogen absorption into electrodeposited metal films is largely influenced by the depositing conditions. We have been investigating the hydrogen absorption into electrodeposited platinum (Pt) films that depends on a change in hydrogen adsorption state with applied potential.1 The microstructure of electrodeposited Pt films was affected by the absorbed hydrogen.2 In this study, we investigate an atomistic state of absorbed hydrogen in electrodeposited Pt films.
Pt films were potentiostatically deposited on a gold foil from a solution containing 0.024 mol dm-3 K2PtCl4 at pH of 0.8. A Ag/AgCl electrode was used as the reference electrode and a Pt plate was used as the counter electrode. The amount of hydrogen in samples was measured by thermal desorption spectroscopy (TDS) in a temperature range between 300 and 1100 K. The amount of hydrogen in deposited Pt films was calculated by subtracting the total amount of desorbed hydrogen of the gold foil substrates from that of the samples.
The amount of hydrogen in potentiostatically deposited Pt films (+0.1 ~ -0.3 V vs. Ag/AgCl) as a function of film thickness is summarized in Fig. 1. The amount of hydrogen was nearly 0 for Pt films deposited at +0.1 V (Fig. 1 ●). It was 1 ~ 2×10-7 mol cm-2 and independent of the film thickness at 0 V (Fig. 1 ◇). For the Pt films deposited at -0.1 and -0.2 V, a positive correlation was observed between the amount of hydrogen and the film thickness (Fig. 1 ○ and △), respectively. The positive correlation of ca. 1.7×10-7 mol cm-2 µm-1 indicates that hydrogen was uniformly contained at atomic ratio ([H]/[Pt]) of 0.015 in the Pt films. For the Pt films deposited at -0.3 V, the positive slope, that is, content of uniformly absorbed hydrogen was much larger than that for the films deposited at -0.1 and -0.2 V (Fig. 1 □). Positive vertical intercepts of 2 ~ 6×10-7 mol cm-2 for -0.1 ~ -0.3 V indicate that a certain amount of hydrogen was contained even in the initial deposits. Pt deposition at +0.1 V onto the Pt film deposited at 0 V reduced the amount of hydrogen to nearly 0. The Pt deposition at 0 V onto the Pt film deposited at +0.1 V increased the amount of the hydrogen to ca. 1×10-7 mol cm-2. These results suggest the possibility that the certain amount of hydrogen indicated by the vertical intercepts of Fig. 1 exists near film surface.

Acknowledgements

The present work was partly supported by JSPS KAKENHI (JP26289276 and JP17K06864).

References

A. Yokoyama, S. Karatsu, M. Sumikawa, N. Fukumuro, and S. Yae, ECS Trans., 75(52) 55 (2017).

N. Hisanaga, N. Fukumuro, S. Yae, and H. Matsuda, ECS Trans., 50(48), 77 (2013).

Figure 1
Lanthanum Nickelate Cathode Materials for Low and Intermediate Temperature for Solid Oxide Fuel Cells
Authors: Lee John In , Park Ka-Young , Park Jun-Young 
Published: February 2020

Solid oxide fuel cells (SOFCs) are a clean electrochemical conversion devices from chemical energy of fuel to electrical energy. SOFCs are considered as future green energy devices because of their diverse advantages including high energy conversion efficiency, various fuel acceptance, and negligible gas pollutants [1]. Now, the performance of SOFCs is highly affected by the oxygen reduction reaction (ORR) in the cathode of SOFCs. Until now, the major materials of cathode are cobalt-contained perovskite oxides because they show a low over-potential for ORR with the high SOFC performance [2]. However, cobalt-contained perovskite cathode materials also have several technical issues, such as expensive price, low chemical stability, and big difference of thermal expansion coefficient (TEC) to the zirconia-based electrolyte. The TEC of cobalt-contained perovskite oxides is 20-25×10-6K-1, whereas the yttria-stabilized zirconia and lanthanide-doped ceria electrolytes are 11-13×10-6K-1. This can results in the delamination of cell components during high temperature operation [3]. On the other hand, the TEC of lanthanum nickelates (Lan+1NinO3n+1) is 11-12×10-6K-1, which is similar to that of electrolyte materials and thus high thermal stability is expected for the SOFC[4]. Hence. in this work, the characteristics of lanthanum nickelates in terms of performance and durability are investigated.
References
[1] K.T. Lee, E.D. Wachsman, Science 334 (2011) 935.
[2] W. Zhou, Z. Shao, J. Power Sources 192 (2009) 231.
[3] S. Pang, X. Xi, J. Power Sources 326 (2016) 176.
[4] R.K. Sharma, E. Djurado, J. Power Sources 325 (2016) 337.
[5] C. Nicollet, J. Grenier, ECS Trans (2015) volume 68,issue 1, 837-845.
[6] C. Laberty, A. V. Virkar, Electrochem. Solid-State Lett (2007) volume 10, issue 10,B170-B174.
Electrochemical Study of Photocatalytic Activity Enhanced By Plasmon Resonance
Authors: Velasco Tinajero Esteban 
Published: February 2020

Titanium oxide has been proven the most promising material for water treatment via Advance oxidation process (AOP) due to its low recombination rate and high capacity to generate hydroxyl radicals, its most important downside is restricted photocatalytic activity to the UV range. Enhancing photocatalytic activity under visible light has been the objective of a lot of researchers around the world. Plasmon resonance in conjunction with traditional semiconductor photocatalyst provides an opportunity to understand and improve on the already useful properties of titanium oxide. The present study is focused on the interaction of an anodized titanium surface (ATS) and silver nanoparticles (Ag-NP) deposited on the ATS by photo electrochemical electroless reduction. Photocatalytic activity enhanced by plasmon resonance is expected to improve the material activity in two fronts, via the metal semiconductor junction where the electron hole (e/h) separation and fast lane charge transfer are induced, and a second front where localized surface plasmon resonance (LSPR) benefit photocatalysis by enabling visible light response, enhancing Visible/UV absorption, local electric fields reducing (e/h) diffusion length, generation of LSPR powered (e/h), local heating effects, lastly molecule polarization.
ATS was form by anodic oxidation of a titanium sheet at 30 V for 120 minutes in an organic electrolyte compose of ethylenglicol, NH4F and water at 5%. Subsequently Ag-NP were deposited by photoreduction of 0.1 M AgNO3, The material was characterized by cyclic voltammetry and scanning electron microscopy. The photo response to visible and UV light was evaluated by zero-current chronopotenciometry. The ATS/ Ag-NP system was successfully fabricated showing a porous titanium oxide surface, decorated by Ag-NP with a uniform size of around 60 nm. Results shows an increase in the visible light response provoked by the silver deposit, the way the photocatalytc response is affected appears to be dependent on the amount of silver deposited, and the size of the particles. Further studies on the effect of the nanostructures over the photocatalytic activity are being conducted.

Figure 1
Theoretical Analysis of Li Insertion/Desorption Reaction at Li
x
C6/1M LiPF6 EC Solution Interface Using Density Functional + Implicit Solvation Model
Authors: Haruyama Jun , Ikeshoji Tamio , Otani Minoru 
Published: February 2020

A fundamental approach to solve energy-related issues is the development of a stable energy storage device. Lithium-ion batteries (LIBs) are one of the most promising candidates because of their high energy density and long cycle life. Charge transfer reactions at electrode/electrolyte interfaces is regarded as a main factor limiting the performance of LIBs.1,2 In this study, we focus on Li insertion/desorption reaction R at the interface between graphite anode and 1 M LiPF6 EC solution:
Li
n
C6m
→ Li
n

-1C6m
+ Li+(EC) (R).

Methods

We applied density functional theory (DFT) + effective screening medium (ESM) method3 combined with reference interaction site method (RISM);4 ESM-RISM calculation treats graphite surface (Li
x
C6 slab + Li+) and liquid solution (1 M LiPF6 EC) by quantum mechanics and implicit solvation model, respectively.5 ESM-RISM calculations were performed on the configuration of a vacuum/slab/solvent system as shown in Figure 1, where the DFT slab domain is on the left-hand side, and the RISM solvents (EC, Li+, and PF6
−) treated by the RISM equations are on the right-hand side. The Li insertion/desorption path (reaction R) was assumed as a combination of one or two straight lines, as indicated in Figure 1. The reacting Li was moved from the stable Li site in the graphite layer (r = 0) to the interior region of the solution. In the ESM-RISM calculations, the distribution function of the solvation is automatically formulated for the solvation/desolvation structures.

Results

We successfully obtained the energy landscapes of reaction R under the various constant chemical potentials of electron; a profile of the grand potential Ω along the reaction R path as indicated in Figure 1. The activation energy of reaction R at the equilibrium potential is approximately 0.6 eV, which is consistent with the experimental measurements.1,2 In the presentation, we will discuss changes of the activation energy and the surface charge density with changing the Li content x of Li
x
C6 (x=0, 0.5, 1) on two differently tilted graphite (30 and 90 degrees).

References

T. Abe, H. Fukuda, Y. Iriyama, Z. Ogumi, J. Electrochem. Soc.
151, A1120 (2004).

K. Xu, A. von Cresce, U. Lee, Langmuir
26, 11538 (2010).

M. Otani, O. Sugino, Phys. Rev. B
73, 115407 (2006).

F. Hirata, P. J. Rossky, Chem. Phys. Lett.
83, 329, (1981).

S. Nishihara, M. Otani, Phys. Rev. B
96, 115429 (2017).

Figure 1