bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling Electrochemical Polishing of Additive Manufactured Parts. Limits of Secondary Distribution Model in Circulating Flow
Authors: Boucher Aurelien , Fedi Baptiste , Doche Marie-Laure , Hihn Jean-Yves 
Published: December 2020

Additive manufacturing allows to design and to realize parts with complex geometries, which were difficult, even impossible, to obtain by conventional means. Nevertheless, the final surface finish obtained at the end of the 3D printing process do not fit with technological specifications especially due to high roughness levels. Thus, an additional finishing step must be implemented in order to get the expected surface finish. Electrochemical polishing is of great interest because it allows, as main advantage comparatively to tribological ones, to be able to deal with small parts exhibiting high complex shapes and/or material hard to be polished [1]. Electropolishing is an electrolytic process based on the anodic dissolution of the workpiece under constant current or potential [2]. As it is done for electroplating systems, it is nonetheless necessary to uniformize the current distribution lines in the treatment cell, in order to optimize the effect of the finishing on the whole surface of the parts. The ability to provide a relevant simulation of the processing by the help of an accurate modelling is a major issue to ensure its industrial deployment through the development of specific tools and the selection of relevant operating parameters [3]. These processes can be considered as a succession of unitary steps, in order to get the expected degree of surface state; and the simulation may be of great help in the design of the full treatment line-up. In this objective, the use of a secondary current distribution model is a useful first step and gives interesting results if special care is paid to the specificity of electropolishing processes. However, this approach faces limitations because of the agitation into the treatment cell which is not accounted for by the model. A correction is possible by integrating the influence of an average level of agitation on the polarization curves (current vs potential) used in the simulation. The present work describes this model based on secondary current distribution upgraded by considering a global agitation and presents comparison between experimental results and simulations. Eventually, even if the enhanced model improve the prediction ability of the model in term of dissolution rates and roughness reduction, some discrepancies confirms the need to reach a more accurate model, and the conclusion is that the local agitation knowledge at the surface vicinity of the surface to be polished is crucial.
[1] C. Rotty, A. Mandroyan, M-L Doche, J-Y Hihn, Surface & Coatings Technology 307, 125–135 (2016)
[2] P. A. Jacquet, Nature 135,1076 (1935)
[3] V. Urlea, V. Brailovski, Int. J. Adv. Manuf. Technol. 92, 4487–4499 (2017)

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Electrochemical Manufacturing of a p-n Junction Employing Water Solutions
Authors: Felici Roberto , Carla Francesco , Fontanesi Claudio , Giaccherini Andrea , Russo Francesca , Di Benedetto Francesco , Innocenti Massimo 
Published: December 2020

Our society relies on the use of semiconductor devices, which are, so far, fabricated using expensive and complex processes requiring ultra-high vacuum equipment. Here we report on the possibility of growing a p-n junction taking advantage of electrochemical processes based on the use of aqueous solutions. The growth of the junction has been carried out using the Electrochemical Atomic Layer Deposition (E-ALD) technique, which allowed us to sequentially deposit two different semiconductors, CdS and Cu2S on a Ag(111) substrate, using water based solutions containing Cd2+, Ag+ and S2- precursors [1,2]. The main problem, encountered when growing this kind of systems, is related to the unattainable electrochemical characterization of the deposition conditions for the different elements without altering the already deposited layers.
This problem was overcome by performing an in-situ x-ray characterization of the grown layers during the E-ALD process. By this procedure, we were able to find the conditions at which the deposition resulted in the formation of thin layers with crystallographic ordered structures and reduced surface/interface roughness. The electronic transport properties of samples, made of 9 nm of Cu2S on top of 10 nm of CdS, have then been determined ex-situ. The samples showed a good stability in air and the I-V characteristic, measured in several positions of the sample, to investigate the homogeneity of the response, is the one typical of a diode.
The present study is funded by the PRIN Project (“Progetti di Ricerca di Rilevante Interesse Nazionale”), “Novel Multilayered and Micro-Machined Electrode Nano-Architectures for Electrocatalytic Applications (Fuel Cells and Electrolyzers)”, grant number 2017YH9MRK.

References

[1] F. Carlà, et al., The Journal of Physical Chemistry C 118 (2014) 6132-6139
[2] A. Giaccherini, et al., Scientific reports 7 (2017) 1-10
Electrodes Two-Phase and pH Boundary Layers Multiphysics Modelling in a Hydrodynamic Alkaline Water Electrolyzer
Authors: Mandin Philippe , LE Bideau Damien , Sauvage Thierry 
Published: December 2020

The presented work is a multiphysics calculation using Ansys-Fluent® CFD modelling of a hydrodynamic alkaline water electrolyzer. This work will start with an exhaustive review of the transport properties necessary for the multiphysics modelling of alkaline water electrolyzer. A recently published article provides experimental data and the correlations needed to calculate thermo-physical properties such as electrical conductivity, density, viscosity, heat capacity, heat and mass transfer diffusion coefficients as a function of temperature and electrolyte mass fraction for two classical alkaline electrolytes (KOH, NaOH). Different interpolation models from various authors are compared to raw experimental data. The goal of this work was to give to the modeler the correlations needed for the simulation of alkaline water electrolysis.
Thus, the two electrodes two-phase boundary layers can be calculated with precision. Calculations under discrete phase modelling (DPM) and Euler-Euler hypothesis have been performed and are presented.

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Integrated Alkali-Electrochemical Process for Wastewater Treatment
Authors: Jafari Maasoomeh , Botte Gerardine G. 
Published: December 2020

Solid waste mismanagement causes environmental contamination. Sewage sludge is the byproduct of the wastewater treatment process and contains pathogenic organisms (e.g Salmonella spp., Escherichia coli, etc.). Anaerobic digestion is widely used for sewage sludge treatment. However, the major drawback of this process is the sluggish rate of sludge biodegradation. Therefore, the retention time in the typical digester is long (between 20-30 days) which consequently results in substantial energy consumption. On the other hand, approximately 50- 60 % of the operational cost in the wastewater treatment plant is dedicated to the treatment and disposal of waste. Hence, it is essential to develop a treatment method to decrease energy consumption.
Alkaline treatment is an attractive process for sludge destruction and improvement in the sludge biodegradability. Furthermore, electrochemical oxidation of the organic materials is an environmentally friendly alternative pathway to disintegrate the sludge microbial cells and eliminate the pathogen bacteria from biosolid for safe disposal. Therefore, the combined alkaline electrochemical technique could expedite waste degradation by using the synergetic functions and increase efficiency of the treatment.
To overcome the challenges related to the conventional treatment method, our research group has developed a novel, energy-efficient mixed alkali-electrochemical sludge treatment in a membraneless electrochemical system at room temperature and low applied potential. In this study, the bimetallic (platinum-iridium) nanocatalyst was synthesized with modified polyol method. The thermal behavior of the raw sludge and the residue biosolid after electrolysis was evaluated by using thermogravimetric analysis (TGA). To determine the effect of electrolysis on the chemical structure of biosolid, the Fourier-transform infrared spectroscopy-Attenuated Total Reflection (FTIR-ATR) and elemental analysis techniques were applied. Ammonia was produced as a byproduct of the waste treatment which can be converted to hydrogen through electrolysis. A considerable amount of solid reduction was achieved by implementing a short electrolysis treatment which diminished the waste transportation and disposal cost to a large extend. Furthermore, the energy consumption was significantly lower than the previous research studies. In this presentation, results from this study including (i) the electrochemical performance of catalyst for sewage sludge treatment (ii) pathogen disinfection and (iii) biosolid characterization will be provided.
Mild Synthesis of Cyclohexanol and Cyclohexanone Via Electrocatalytic Reduction of Phenols Using Dispersed Metal Catalysts
Authors: Wijaya Yanuar Philip , Smith Kevin J. , Kim Chang Soo , Gyenge Elod 
Published: December 2020

Cyclohexanol and cyclohexanone are industrially important chemicals for the synthesis of Nylon polymers. On the industrial scale, they are produced by thermocatalytic processes, either phenol hydrogenation (140–170 oC, 1 atm) or cyclohexane oxidation (140–180 oC, 0.8–2 MPa), which require high temperatures and external gas supply. This work demonstrates that electrosynthesis of cyclohexanol and cyclohexanone can be done at mild conditions using diverse aqueous electrolytes and dispersed metal catalysts (Pt/C, Ru/C, and Pd/C).
Electrocatalytic hydrogenation (ECH) of lignin-derived phenols (e.g., guaiacol and phenol) is performed in a stirred slurry H-cell under potentiostatic or galvanostatic control. Dilute mineral acid (H2SO4, HClO4), organic acid (CH4SO3), and inorganic salt (NaCl) worked efficiently as the electrolyte solutions. In the ECH of guaiacol at low temperatures (35–40 oC) and low Pt/C loading, high guaiacol conversions (83–96%) and Faradaic efficiencies (40–70%) were achieved with significant cyclohexanol selectivities (45–53%) after 4 h reactions. In the ECH of phenol, full conversion to cyclohexanol was achieved after 2 h with high current efficiency (90%). Remarkably, by pairing the NaCl catholyte and H2SO4 anolyte, the activity of Ru/C and Pd/C can be dramatically improved, showing the importance of electrocatalyst and electrolyte synergy in the ECH of phenolic compounds.
The stirred slurry catalyst allows the cell to operate at the industrially relevant current densities (in this work, between 100–300 mA cm-2). Dispersion of the negatively charged catalyst particles in the solution also facilitates the mass transfer between the organic molecules and chemisorbed hydrogens through physical collisions during the reaction, thereby improving the ECH efficiency. Mild electrocatalytic reduction of phenolic compounds represents a promising route for selective and efficient production of renewable chemicals from biomass.
Synthesis and the Cathode Properties of Na3Fe3(PO4)4 for Sodium-Ion Battery
Authors: Okada Masaki , Chiba Kazuyuki , Matsunaga Osamu , Kobayashi Wataru , Takahara Toshiya , Takahashi Kennichi , Okada Shigeto 
Published: December 2020

Na-ion batteries (NiBs) are very attractive and promising for large scale electric power storage system because of the abundance for sodium source, the high cost-effectiveness and the long lifetime. Among the candidate of cathode active materials for NiBs, practical use of iron phosphate such as NaFePO4, Na2FePO4F, and Na3Fe3(PO4)4 [1] or carbonophosphate such as Na3FePO4CO3 [2] is expected from the viewpoint of cost and safety. In order to make full use of the resource and cost advantages of these materials, the raw materials used in the synthesis and the synthesis method are also important. In this presentation, we report the direct synthesis of Na3Fe3(PO4)4 by the hydrothermal method with mass productivity and the cathode properties.
Synthesis was carried out using ferrous sulfate hydrate (FeSO4·nH2O), phosphoric acid, and various sodium phosphate salts as sodium sources with various the raw material composition, hydrothermal treatment temperature, and reaction time. For the purpose of controlling the reaction, synthesis was performed under the condition that an oxidizing agent or a reducing agent was added. The obtained compounds were identified by powder X-ray diffraction measurement and Rietveld analysis.
Iron (Ⅱ) sulfate (FeSO4·7H2O), phosphoric acid (H3PO4), sodium dihydrogen phosphate (NaH2PO4·2H2O) and sodium persulfate (Na2S2O8) were used as raw materials, and hydrothermal synthesis was performed at 200 ° C for 16 hours. From the Rietveld analysis, the obtained compound was assigned to the layered structure Na3Fe3(PO4)4. This hydrothermal synthesis Na3Fe3(PO4)4 delivered initial discharge capacity of 160mAh g-1 between -1.2 and 1.3 V with a reference electrode of Ag/AgCl at 2 mA cm-2 in the 17 m NaClO4 aqueous solution (Figure 1). In the presentation, we will be reported the details of cathode properties of Na3Fe3(PO4)4.
References:
[1] G. S. Shinde, R. Gond, M. Avdeev, C. D. Ling, R. P. Rao, S. Adams, P. Barpanda, Mater. Res. Express, 7 (2020) 014001.
[2] B. Xie, R. Sakamoto, A. Kitajou, K. Nakamoto, L. Zhao, S. Okada, Y. Fujita, N. Oka, T. Nishida, W. Kobayashi, M. Okada, T. Takahara, Sci. Rep., 10 (2020) 3278.

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Using Impedance to Quantify Transport Losses in Alkaline Water Electrolysis Electrode Catalyst Layers
Authors: Reumert Alexander Kappel , Sunde Svein 
Published: December 2020

Anthropogenic climate change has brought on a global climate crisis and emergency. Increased levels of atmospheric carbon dioxide levels has brought with it undesirable changes to the world’s climate. To halt and eventually stop this trend the world needs to move to zero-carbon sources of electricity, transport and chemical production.
To offset the variability in zero-carbon electricity sources storage or usage of the excess energy is necessary. One of several technologies to achieve this is water electrolysis. A promising candidate of this field of study is Alkaline Water Electrolysis
The field of alkaline electrolysis have recently moved from a gap-based macro-material approach to a nanomaterials based membrane cell architecture.
Due to recent advances in membrane technology both ion-conduction and electrolyte solvating membranes allow for a zero-gap cell architecture. With this approach comes new engineering challenges. Bubble formation, -diffusion, -suppresion, and –transport are all phenomena that are relatively unexplored in the context of nanopowder-based electrodes in fully flooded aqeous KOH systems.
One of the ways of exploring this is the use of Galvanostactic Electrochemical Impedance Spectroscopy (GEIS).
Through GEIS investigations and Distribution of Relaxation Times of the electrochemical response of nano-powder based cathodes a Gerischer-like response can be observed indicating transport issues and a way of quantifying this.
(Invited) Development of Polymer Electrolyte Membrane Fuel Cell Models for Transportation Applications Using Sequence of Direct Simulation Methods
Authors: Shimpalee Sirivatch , Satjaritanun Pongsarun , Dutta Sandip , Van Zee John William , Weidner John W. , Hirano Shinichi 
Published: December 2020

Augmentation of fuel cell performance at high current densities, particularly under automotive application, is important to improve the overall power density and to reduce the cost of proton exchange membrane fuel cell (PEMFC) systems. Primarily, the fundamental non-linearity of the equations governing PEMFC performance on a three-dimensional model necessitates iterative solutions. As of now, mass transport over-potential is a major barrier to achieving high performance at a high current density. Condensed water, specifically in the gas diffusion layer, decreases oxygen transport to the oxygen reduction reaction area. Experimental investigations of oxygen transport are limited by an inability to resolve the water saturation-dependent properties.
The alternative approach to comprehend and overcome transport resistances, predominantly inside the gas diffusion layer, is to use advanced mathematical modeling. The timeline of direct simulation techniques using in PEMFC will be presented including the Lattice Boltzmann method (LBM) which is an alternative advanced modeling technique [1-12]. This LBM can be implemented into existing models to visualize the transports inside the structure of microscale geometries, such as: a gas diffusion layer (GDL), micro porous layer (MPL), and catalyst layer (CL). The study where the goal was to couple the conventional computational fluid dynamics (CFD) model in the macroscale geometry and LBM in the microscale geometry using the technique called co-simulation will be presented. The understanding of local kinetic activity inside nanoscale CL implemented into the model will also be discussed. The completion of this model development can enhance the potential capability of a model-based investigation of mass and heat transports to find solution of designs and operational conditions in the PEMFC for automotive applications.
References:

S. Dutta et al., J of Applied Electrochemistry, 30, 135-146, 2000

S. Shimpalee et al., J. of Power Source, 135, 79 – 87, 2004.

S. Shimpalee et al., J. of Power Sources, 160, 398-406, 2006.

S. Shimpalee et al., Int. J. of Hydrogen Energy, 32/7, 842-856, 2007.

S. Shimpalee et al. Electrochemica Acta, 54, 2899-2911, 2009.

S. Shimpalee, J. of Electrochem. Soc, 161(8), E3138-E3148, 2014.

V. Lilavivat et al., Electrochimica Acta,174,1253–1260, 2015.

S. Shimpalee et al., J. of Electrochem. Soc., 164(11), E3073-E3080, 2017.

P. Satjaritanun et al., J. of Electrochem. Soc., 164(11), E3359-E3371, 2017.

P. Satjaritanun et al., J. of Electrochem. Soc., 165(13), F1115-F1126, 2018.

S. Shimpalee et al., J. of Electrochem. Soc., 166(8), F534-F543, 2019.

P. Satjaritanun et al., J. of Electrochem. Soc., 167(1), 013516, 2020.
Unified Framework for the Finite Element Modeling of Li-Based Batteries with Liquid Electrolyte
Authors: Andrei Petru , Tan Kenley 
Published: December 2020

Despite the high demand for accurate electrochemical simulations tools that can compute the d.c. (charge and discharge), a.c. (i.e. electrochemical impedance spectroscopy), and transient characteristics of electrochemical devices, there is currently a lack of such simulation environments in the literature. Most often, the different research groups and institutions are writing their own custom simulators that usually work only for specific battery configurations and chemistries. Even more advanced commercial simulators, such as Comsol Multiphysics, have a few modules that can simulate batteries, however, these modules can simulate only specific chemistries such as Li-ion or Li-air batteries and do not have a more general electrochemical device simulator that can simulate any general, user-designed device.
In this presentation, we summarize our efforts to build such a tool, starting from the numerical implementation of the transport models to problems associated with the discretization and numerical solution of transport equations. We focus on how to design a unified framework for designing electrolytes, modeling ion transport in the electrolyte and electron transport in the electron conductive materials, and interface phenomena such as double layer effects, SEI layers, and the multitude of possible chemical and electrochemical reactions that can take place once the system is designed. In our tool, the transport in the electrolyte is governed by a modified concentrated solution theory written in the form of a generalized Nernst-Planck model. The a.c. analysis is performed by linearizing the discretized system of differential equations and using the linear perturbations theory on the finite element grid. More details about the formulation of the mathematical model, state variables, electrochemical reactions, microstructure modeling, and numerical implementation will be discussed at the conference. Specific examples for the simulation of Li-ion, Li-air, Li-S and other Li-based systems (symmetric and asymmetric cells) will also be presented.
(Invited) Application of Microelectrode Technique to Battery Materials Study
Authors: Nishikawa Kei , Shinoda Keisuke , Kanamura Kiyoshi 
Published: December 2020

Li-ion batteries use the “composite electrode” which includes active materials, conductive agents, binder, and current collector. In general, the electrode characteristics is affected by not only the active materials property but also the state of “composite”. The state of “composite” has many parameters, for examples, mixing ratio, tap density, thickness, and so on. In order to understand the electrochemical characteristics of an active material, the microelectrode technique is very important. Under microscope observation, the microelectrode is contacted to one active material particle by using micromanipulator. Then, we can evaluate the electrochemical characteristics of one particle. In this presentation, we will introduce the results of “single particle measurement” for Si, LiCoO2, LiNi0.5Mn1.5O4, and so on.
In addition, microelectrode technique is also useful for the study of Li metal electrode. Li metal electrode is suffered from dendrite growth during charging, and dead lithium formation during discharging. These phenomenon are mainly induced non-uniformity of the current distribution. In addition to that, SEI (solid electrolyte interphase) should play an important role for the morphological variation of the electrodeposited Li metal. Many researches were conducted based on the surface chemistry in order to reveal the relationship between the nature of SEI layer and the morphology of electrodeposited Li metal. However, the localization of the electrodeposition sites is an obstacle for the quantitative analysis in order to discuss the dendrite initiation and growth. In our study, microelectrode was utilized to observe the morphological variation of the electrodeposited Li metal. Constant current electrodeposition was conducted to observe the electrodeposited Li metal. After the electrodeposition, the microelectrode was transferred to FE-SEM or TEM with transfer vessel without air exposure. Ex-situ SEM and TEM observation was done to discuss the electrolyte effects to the morphology of electrodeposited Li metal. We also would like to introduce the typical results of the morphological variation and SEI nature of the electrodeposited Li metal.

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