bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Characterization of Cu2s Cathode Prepared By Spray Pyrolysis with Heat Treatment
Authors: Kalimuldina Gulnur , Taniguchi Izumi 
Published: February 2020

Introduction

In the modern society, the requirements for the capability of existing LIBs are not satisfying and motivates researchers for the development of the more powerful energy storage systems. In response to the urgent environmental and energy issues, the cathode materials’ improvement is considered as one of the solutions in the way of fulfilling the demand for high capacity and sufficient energy density rechargeable batteries [1-2].
Copper sulfides became a topic of considerable interest and importance because of their theoretical capacity 337 mAh g-1 for Cu2S and 560 mAh g-1 for CuS with flat and prolonged charge/discharge plateaus [3].
In this work, we have synthesized Cu2S with Cu/S≈2 elemental ratio by spray pyrolysis followed by heat treatment and physical and electrochemical characterizations of the material were investigated.

Experimental part

The preparation of Cu2S powder was carried out by dissolving copper (II) nitrate trihydrate (Cu (NO3)2·3H2O) and thiourea (CS (NH2)2) in the molar ratio range of Cu: S from 2 to 0.5. The sprayed droplets carried by N2+3%H2 gas inside the reactor and the reactor temperature was varied from 400 to 700 ºC. Afterwards samples were sintered in the temperature range from 400 to 600 ºC in a N2+3%H2 gas atmosphere for 2 h.
The cathode slurry was prepared by mixing 80:10:10 wt.% of Cu2S, polyvinylidene fluoride (PVdF) and acetylene black (AB) in 1-methyl-2-pyrrolidinone (NMP). The coin-type cells (CR2032) were assembled with 1 M LiTFSI in 1:1 w/w in DOL/DME electrolyte and lithium metal foil used as a reference electrode in a high purity Ar gas atmosphere (99.9995% purity). The cell performance test was performed for charge/discharge cyclability in a voltage range of 1.0-3.0 V where 1C was used as 337 mA g-1.

Results and discussion

In Fig. 1 the rate capability of Cu2S is presented. Stoichiometric Cu2S prepared at SP 400 ºC and further annealing at 460 ºC for 2h of Cu:S=1 molar ratio solution revealed the 1st discharge capacity of 330 mAh g-1 (98% of its theoretical capacity) at 0.1C. Upon cycling, the cell capacity kept at 270 mAh g-1. With the increase of the C-rate the capacity gradually decreased to 220 mAh g-1 at 30C. The Coulombic efficiency was retained at about 100% value from 0.1C to 10C rate and dropped to 95% at 30C. The prepared Cu2S demonstrated relatively stable capacity value between 0.1C and 30C without severe decay and with good charge/discharge reaction reversibility.

References

[1] B. Scrosati, J. Garche, J. Power Sources, 195 (2010) 2419-2430.
[2] B. Jache, B. Mogwitz, F. Klein, P. Aldelhelm, J. Power Sources, 247 (2014) 703-711.
[3] X. Meng, S.C. Riha, J.A. Libera, Q. Wu, H.-H. Wang, A.B.F. Martinson, J.W. Elam, J. Power Sources, 280 (2015) 621-629.

Figure 1
Self-Polymerized Dopamine As an Organic Cathode for Lithium-Ion Batteries
Authors: Liu Tianyuan , Lee Byeongyong , Lee Seung Woo 
Published: February 2020

The redox-active organic materials have been intensively investigated as promising candidates for replacing the inorganic cathodes in lithium-ion batteries (LIBs). In particular, quinone-based organic molecules, such as benzoquinone, naphthoquinone, and anthraquinone, have received considerable attention owing to their high redox potential, high theoretical capacity (up to 500 mAh g−1), and possibility of being synthesized from earth-abundant resources. However, these quinone derivatives cannot be directly used in common LIBs because of their high solubility in non-aqueous electrolytes.
Dopamine, which has a similar molecular structure with adhesive proteins in mussel, can be self-polymerized on various types of substrates. It is interesting to note that one of the oxidation intermediates of dopamine, 5, 6-indolequinone, resembles the structures of benzoquinone and naphthoquinone, having a high theoretical capacity of 364 mAh/g. Despite its intrinsic redox characteristic of the quinone groups,1 the redox-active properties of the polydopamine (PDA) with lithium ions have not been reported yet. Here, we first demonstrated PDA as a promising organic cathode in LIBs. PDA showed a specific capacity of ~235 mAh/g at 0.14 C and ~140 mAh/g at ~27.4 C. We also investigated the energy storage mechanism in PDA and confirmed the existence of both electrical double-layer capacitance and pseudocapaitance. By using carbon nanotubes (CNTs) as 1D templates for the polymerization of dopamine, we prepared flexible PDA and CNT composite films. The composite films exhibited enhanced rate capability and excellent cycling stability owing to the unique combination of redox-active PDA and superior electrical conductivity of CNT.

References:

(1) M. D. Hawley, S. V. Tatawawadi, S. Piekarski, and R. N. Adams, J. Am. Chem. Soc., 89, 447 (1967).
Characteristics Analysis of NaNiCl2 Battery for Applying to Ships
Authors: Ahn Jong-Woo , Roh Gill-Tae , Park Ki-Do , Kim Kyung-Hwa 
Published: February 2020

Marine equipment and shipping industries have done research to develop high efficient and environment-friendly ship technology to deal with IMO's air pollutant regulation from ships. Nowadays research on marine power generation and propulsion system based on the secondary battery, which is enable to charge and discharge and has high energy density, has been spotlighted in the world. Among the secondary batteries, NaNiCl2 battery is used in buildings, transportation by land due to high efficiency and safety. To apply the NaNiCl2 battery to ships, its safety in marine environment condition has to be proved. In this paper, the testbed developed for inclining and vibration experiments and test results are introduced.
CV Measurement of New Redox Flow Battery Electrolyte Using Single Fiber Electrode
Authors: Narita Ayumi , Sato Yukari , Kaneko Yuji , Negishi Akira , Nozaki Ken , Kato Tohru 
Published: February 2020

Redox flow batteries (RFB) are one of the candidates for large-scale energy storage systems to solve the issues of power variation with renewable energy. All-vanadium RFBs have strongly developed up to now [1], because their electrolyte includes only vanadium ions in both half-cells as active materials, avoiding cross-contaminations. In order to supply RFBs to the world, it is required to lower the production costs and use the material which is rich in natural resources.
In last year, Sumitomo Electric Industries, Ltd. published new type of RFBs using titanium (Ti) and manganese (Mn) as active materials [2]. This RFB have been expected to lower the costs, and avoid the cross-contamination by using Ti (IV) and Mn (II) mixed aqueous electrolyte in both positive and negative electrodes. Moreover, they presented that the mixed electrolyte prevents the precipitation of MnO2 in the electrolyte. However, details of electrode reactions between Ti (IV) and Mn (II) electrolyte and the carbon fiber have not been understood, yet. To improve the performance of this new RFBs, it is significantly important to reveal how the reaction occurs on the surface of the electrode.
In previous study, we reported the characterization of all-vanadium RFB electrodes using single fiber electrodes [3]. The results showed the differences of electrochemical property each one of the carbon fibers, and the observation of the electrode reaction for vanadium ions. In the presentation, we demonstrate CV results in Ti (IV) and Mn (II) electrolyte using the single fiber electrode.
Acknowledgments
This work was supported by a grant from Ministry of Economy, Trade and Industry (METI) which is re-entrustment from Sumitomo Electric Industries, Ltd. The authors wish to thank them deeply.
References
[1] T. Shigematsu, SEI Technical Review, 73, 1 (2011).
[2] Y. R. Dong, H. Kaku, K. Hanafusa, K. Moriuchi and T. Shigematsu, ECS Trans. 69, 59 (2015).
[3] A. Narita, Y. Kaneko, Y. Sato, A. Negishi, K. Nozaki and T. Kato, ECS Trans. 68, 89 (2015).
Podiform Graphene-Sulfur Composite for Lithium Sulfur Battery
Authors: Guo Yi , Zhang Yun 
Published: February 2020

A podiform graphene and sulfur composite is prepared by a facile lyophilization method followed by low-temperature heat treatment for high-performance lithium sulfur battery. SEM, EDS, XRD and TG are used to characterize the morphology and structure of the material. Sulfur nanoparticles are physically trapped inside the podiform graphene like beans. Graphene serve as a conductive framework for electrode material. Meanwhile, the podiform structure not only constrain the dissolution of polysulfide, but also accommodate the volume expansion during the charge/discharge process. As a consequence, the as-designed graphene-sulfur electrode deliver an initial specific discharge capacity of 1538 mAh g-1 at 0.05C. It still can exhibit a capacity of 674 mAh g-1 at 2C after 100 cycles. Good performance of the graphene-sulfur composite can attribute to the unique podiform structure.
The Kinetics of the Metastable Pit Nucleation on Metal Surfaces
Authors: Lu Pin , Engelhardt George , Macdonald Digby D. 
Published: February 2020

The theory for kinetics of nucleation of metastable pits in terms of the Point Defect Model (PDM) has been applied the first time to describing the evolution of the nucleation rate of metastable pits on a variety of metallic substrates. The PDM successfully accounts for the experimental data that have been reported in the literature on stainless steel, carbon steel, iron, aluminum, and Alloy-22, and which are judged to be reliable and reproducible. Important fundamental parameters related to metastable pitting such as total number density of pitting nucleation sites, dissolution time of the cap over the pit, energy related to absorption of the aggressive ions into oxygen vacancies in the surface of the barrier layer, vacancy condensation rate, and the time at which the nucleation rate of metastable pits is maximum were obtained from the optimization of the PDM on the experimental data, as reported in the present paper. The values obtained for those parameters are in good agreement with values and observations reported elsewhere. The present work successfully demonstrates the capacity of the PDM in accounting for experimental observations of metastable pitting and that the PDM can be applied as an underlying theory for studying and understanding metastable pitting on metal surfaces.
Direct Measurement of the Dissolution of Valve Metals Under High Field Anodisation Conditions
Authors: Hassel Achim Walter , Kollender Jan Philipp 
Published: February 2020

Valve metals such as Ti, Nb and Ta react spontaneously with water or oxygen forming dense oxide layers on their surface. These thin passive layers are protecting the metals from further corrosion. Anodisation can be used to increase the thickness of the passive layers for an improved corrosion and wear resistance. Oxide growth during anodisation occurs via ion transport through the oxide film under high field conditions.
The oxide growth process during anodisation of valve metals has been investigated in detail in the past. Most widely used for the description of the oxide growth mechanism during anodisation is the high field model [1]. However, there is one parameter that cannot be described by the high field model or any other existing model that is the metal dissolution during oxide growth. To date the metal dissolution during anodisation of Nb, Ta and Ti has also never been experimentally observed or quantified. In an attempt to study this phenomenon a flow-type scanning droplet cell microscope (FT-SDCM) [2] which is directly coupled to inductively coupled plasma mass spectrometry (ICP-MS) [3] was used. By means of this technique it was possible to investigate the time and potential dependent metal dissolution during anodisation. Additionally the influence of the pH value of the used electrolyte was investigated.
All experiments showed an overshoot in metal dissolution during the initial stage of oxide growth. The dissolution rate stabilized into a constant plateau (stationary dissolution) after this initial period for all investigated materials.
In acidic electrolytes a constant increase of the overall amount of dissolved metal was observed when increasing the anodisation potential. For neutral electrolytes on the other hand the exact opposite was observed. Higher formation potentials were leading to lower dissolution rates. Furthermore, a direct potential - independent proportionality between the amount of charge carriers crossing the electrolyte-oxide interface and the amount of dissolved metal during anodisation was observed. The measured dissolution rates were highest for Ti and lowest for Ta under all investigated pH values. Interestingly almost exactly one order of magnitude difference in dissolution rate between each of the three investigated materials was found.
For a better understanding of the observed dissolution behaviour electrochemical impedance spectroscopy was performed under oxide formation conditions for each investigated material. Differences were significant in the film resistance depending on the pH value of the electrolyte. They could be used to rationalise the observed dissolution behaviour.
____________
[1] M. M. Lohrengel, Mater. Sci. Eng. R. 11 (1993) 243
[2] J. P. Kollender, A. I. Mardare, A. W. Hassel et al., J. Electroanal. Chem. 740 (2015) 53
[3] A. I. Mardare, J. P. Kollender, A. W. Hassel et al., Electrochem. Comm. 59 (2015) 5
pH Sensing Electrochemical Cell to Investigate Anodic Dissolution of Magnesium
Authors: Miyazawa Kei , Hoshi Yoshinao , Shitanda Isao , Itagaki Masayuki 
Published: February 2020

Magnesium (Mg) is widely used as the automobile parts and biomedical materials because it is lightweight and high strength material. However, it is well known that Mg has large corrosion rate, which limits the application of Mg. The hydrogen evolution rate on Mg increases with noble potential from corrosion potential. This phenomenon is called the Negative Difference Effect (NDE).1-8) The effect of pH on the Mg dissolution and hydrogen evolution during the anodic dissolution is one of the key issue for understanding of NDE phenomenon.4) In the present study, we developed the pH sensing electrochemical cell to investigate the pH changes near the Mg electrode due to the anodic dissolution.
Schematic of the pH sensing electrochemical cell developed in the present study is shown in Fig. 1. The electrochemical cell was constructed using transparent acrylic plates. The working electrode and the counter electrode were placed in compartments separated by a glass filter to avoid the pH changes due to the gas generation on each electrode. Tungsten/tungsten oxide electrode was set closed to the working electrode. Tungsten/tungsten oxide electrode was prepared by the anodic oxidation. The diameter of tungsten electrode was 3 mm. The anodic oxidation of tungsten electrode was performed at 0.52 V vs. SSE in 1 mol dm-3 phosphate buffer solution (pH=1) for 1 min. This electrode was immersed in the buffer solution adjusted to arbitrary pH to evaluate the performance as the pH sensor. The distance between the tungsten/tungsten oxide electrode and the working electrode was 1 mm. The anodic polarization curve measurement of Mg was conducted by three electrode system. The working electrode was the Mg electrode and the counter electrode was Pt wire. The saturated potassium chloride/silver/silver chloride electrode (SSE) was used as the reference electrode. The 1 mol dm-3 sodium sulfate solution was used as the electrolytic solution.
The pH was monitored using the tungsten/tungsten oxide electrode during the anodic polarization curve measurement of Mg electrode. The relation between pH and anodic current of Mg was discussed in the present study.

Reference

[1] G. Song, A. Atrens, D. Stjohn, J. Nairn, and Y. Li, Corros. Sci., 39, 855 (1997).
[2] R.L. Petty, A.W. Davidson, J. Am. Chem. Soc., 76, 363-366 (1954).
[3] G. Song, A. Atrens, D. Stjohn, X. Wu, and J. Nairn, Corros. Sci., 39, 1981 (1997).
[4] L. Rossrucker, A. Samaniego, J.-P. Grote, A. M. Mingers, C. A. Laska, N. Birbilis, G. S. Frankel, K. J. J. Mayrhofer, J. Electrochem. Soc., 162, C333-C339 (2015).
[5] G. S. Frankel, A. Samaniego, and N. Birbilis, Corros. Sci., 70, 104 (2013).
[6] G. Williams, N. Birblis, and H. N. McMurray, Electrochem. Commum., 36, 1 (2013).
[7] G. L. Song and A. Atrens, Ave. Eng. Mater., 1, 11 (1999).
[8] G. L. Song and A. Atrens, Ave. Eng. Mater., 5, 837 (2003).

Figure 1
Development of Empirical Charge Transfer Interatomic Potential for Tantalum Oxide Nanostructures from First Principle Calculations
Authors: Sasikumar Kiran , Narayanan Badri , Sankaranarayanan Subramanian K. R. S. 
Published: February 2020

There has been considerable interest over the years in metal oxides and their nanostructures owing to their exotic properties making them ideal candidates for several applications, notably in electronics, thermal management, catalysis and biochemistry. In particular, mesoporous (2-50 nm pore sizes) tantalum oxide nanostructures can be used for photocatalytic decomposition of water, thermal insulation and molecular adsorption, while Ta2O5nanoparticles have applications in bio-imaging due to their inertness and non-toxicity. It is essential to obtain a clear fundamental understanding of the structure and chemistry of metal oxide nanostructures to optimize the material performance in these applications.
Atomistic molecular dynamics (MD) simulations provide an ideal tool to investigate the underlying mechanisms at play in the nanoscale processes around these nanostructures and to decode the structure-property relationship. The key to a reliable MD simulation is the underlying empirical force field that describes the interatomic interactions. While robust interatomic potentials have been developed for several metal oxides, namely, alumina, titanium oxide, iridium oxide etc., there is no available empirical charge transfer force field to simulate the behavior of tantalum oxide nanostructures and metal-oxide interfaces. This is primarily due to a lack of comprehensive structural and energetics information, both experimental and ab initio theory, on the different polymorphs of Ta2O5.
In this talk, we present a detailed tabulation of ab initio density functional theory (DFT) calculations of structure, cohesive energies and elastic properties for the three main experimentally observed polymorphs of Ta2O5, namely, hexagonal, orthorhombic and monoclinic. The DFT-generated dataset is used to parameterize an EAM+QEQ (Streitz-Mintmire) charge transfer interatomic potential for tantalum oxide via evolutionary algorithms.
Streitz-Mintmire force field is a variable charge potential, which can account for dynamic charge transfer, and has been demonstrated to be a reasonable potential for single-metal oxides. In particular, oxidation of metallic nanoparticles can be investigated using this charge transfer formalism. The developed force field can also be used to investigate Ta/TaO interfaces, the properties of which are significantly affected by the nanostructure of the interface.
In this work, the developed interatomic potential is used to investigate the oxidation of tantalum thin films and nanoparticles. The thermal and mechanical stability of tantalum oxide nanoparticles and mesoporous nanostructures, and the atomic scale processes (oxidation and sintering) that occur in the vicinity of these nanoclusters are also investigated.
In Situ Optical Investigation of H2s Impact on Carbon Oxidation in Operating Solid Oxide Fuel Cells
Authors: Kirtley John D , Qadri Syed Noorullah , Steinhurst Daniel A , Owrutsky Jeffrey C 
Published: February 2020

While solid oxide fuel cells (SOFCs) promise efficient electricity production and high fuel flexibility, trace sulfur and chlorine constituents commonly found in desirable fuel sources such as syngas and biogas pose challenges. Sulfur poisoning is a well-established phenomenon that can lead to rapid loss of electrochemical performance in SOFCs that operate at high temperatures (650 – 800 °C). State-of-the-art Ni/YSZ (yttrium stabilized zirconia) anodes lose significant catalytic activity upon exposure to even ppm-levels of H2S, but details regarding how the catalyst degrades and the specific effects on electro-catalytic processes remain unclear. One approach to solving this shortcoming is to understand the degradation mechanisms through real time correlation of electrochemical performance with in situ, molecular specific observations. This current study uses infrared emission from the Ni/YSZ anode surface of an operating SOFC to simultaneously characterize 1) gas species using Fourier transform infrared emission spectroscopy (FTIRES) and 2) temperature changes using near infrared (NIR) thermal imaging. These data are collected with electrochemical potential when the SOFC is operated at 75% maximum current at 700 °C using CH4, with and without 170 ppm H2S added. In situ FTIRES measurements show that the CO2 oxidation product and the CO electrochemical intermediate are suppressed when cell potential deteriorates with H2S present. Simultaneous NIR thermal imaging measurements of surface temperatures show that cooling also reflects evolving processes at the anode. After each trial, electrochemical oxidation of deposited carbon showed that H2S also hindered carbon accumulation. These results together have begun to provide direct insight into how sulfur poisoning affects electrochemical processes in SOFCs through correlations of electrochemical potential, surface temperature changes, and gas species at the anode.