bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shape Anisotropy in Magneto-Impedance NiFe-Based Microsensors
Authors: Cortés Meritxell , Peng Tao , Woytasik Marion , Moulin Johan 
Published: February 2020

MI sensors are based on the impedance variations due to changes of the skin depth when applying an external magnetic field. They present high sensitivity but relative spatial resolution. Thin film technology is an interesting way to reduce size and realize arrays of microsensors.
The present work reports the fabrication and characterization of microsensors based in the MI effect. The sensors consisted in a multilayered structure of two ferromagnetic layers with a copper layer in between. Permalloy has been chosen as magnetic material due to both its magnetic properties and the possibility of obtaining thick layers of this material by means of electrodeposition. Silicon substrates and UV thick photolithography have been used to perform the micromolding of the sensors. Electrodeposition conditions have been optimized in previous works [1]. A post annealing process under magnetic field has been applied in order to study its influence on the sensibility of the sensors. The size of the obtained sensors was from 1 mm x 100 µm to 5 mm x 250 µm. The thickness of the copper and NiFe layers was ranging from 2 to 10 µm.
The optimal excitation frequency leads to a matching between the film thickness and the skin depth, what has been experimentally validated: from 0.8 MHz for 5 µm thick NiFe films to 3 MHz for 2.5 µm thick NiFe films. The sensors have been characterized at these frequencies as a function of the magnetic field and the best results have been obtained for sensors annealed at 300°C under transverse magnetic field. Both the magneto-impedance maximum and the anisotropy field depend on the aspect ratio of the structure what highlights the influence of the shape anisotropy. The narrower structures give the highest maximum of the magneto-impedance (170% of variation of impedance) and to the higher anisotropy field (4200 A/m).
Aqueous Lithium-Iodine Battery
Authors: Byon Hye Ryung , Zhao Yu 
Published: February 2020

Higher energy density and cycling efficiency are required for the next generation of batteries. Iodine is an attractive material towards the high energy density battery thanks to its high theoretical energy density of ~0.74 kWh kg–1 and 3.7 kWh L–1. However, due to the nature of low ionic conductivity of solid lithium iodide, the primary lithium-iodine (Li–I2) batteries can only support for extremely low current rate applications such as a pacemaker. To improve rechargeability and rate capability, we have proposed aqueous cathode with a triiodide/iodide (I3
–/I–) redox couple to construct a low-cost, non-flammable, and environmentally friendly Li–I2 battery.[1-4] The aqueous cathode can contain high concentration of I3
–/I– redox couple using I2 and I– ion, which are transformed to I3
– in an aqueous medium (I2(s) + I– ↔ I3
–, K (equilibrium constant) = 723). The electrochemical reaction of this I3
–/I– redox couple in the aqueous cathode leads the total cell reaction of Li–I2 battery: 2Li + I3
– ↔ 2Li+ + 3I–. This aqueous Li–I2 battery demonstrates high storage capacity (~98% of the theoretical capacity), Coulombic efficiency (>99.5%) and cycling performance (>99.5% capacity retention for 100 cycles), which are thus far one of the highest performance among current Li–I2 batteries, aqueous cathode batteries, and lithium-ion batteries using aqueous electrolyte. In addition, high solubility of the I3
–/I– redox couple and appropriate operating potential (~3.5 V vs. Li+/Li and ~0.5 V vs. SHE) but avoiding the electrolysis of water offer a high energy density of ~0.33 kWh kg–1. This energy density can be further improved when equipped with a flow device and aqueous electrolyte reservoir, which allows the aqueous Li–I2 battery to be grid-scale flow battery applications.

References

[1] Zhao, Y; Wang, L.; Byon, H. R. Nature Communications
2013, 4,1896.
[2] Zhao, Y; Byon, H. R. Adv. Energy Mater.
2013, 3, 1630-1635.
[3] Zhao, Y.; Hong, M.; Mercier, N. B.; Yu, G.; Choi, H. C.; Byon, H. R. Nano Lett.
2014, 14, 1085-1092.
[4] Zhao, Y.; Mercier, N. B.; Byon, H. R. ChemPlusChem
2014, in press.
Free-Standing Type Mixed Oxide Oxygen Electrode for Rechargeable Li–O2 Batteries
Authors: Kalubarme Ramchandra S. , Park Ga-Eun , Park Chan-Jin 
Published: February 2020

The essential prerequisite for the successful operation of a rechargeable Li–O2 battery is the formation of Li2O2 as reaction products during discharging and the decomposion of Li2O2 to Li and O2 during charging. However, one of the critical problems which limit the practical use of the non-aqueous Li-O2 batteries employing carbon based oxygen electrode is the huge polarization during the discharge/charge process. The high cell polarization may be due to the high activation energy required to produce Li2O2 during discharge and to decompose the Li2O2 during charge. It have been reported that the discharge/charge efficiencies can be improved by the addition of catalytic materials to the carbon supported oxygen electrodes. The cathode catalysts can affect the discharge/charge potentials and determine the rechargeability of the cells. Therefore, it is vital to develop an effectively catalyzed oxygen electrode for the oxygen reduction and oxygen evolution reactions in Li–O2 batteries.
In this study, for the first time we introduce a free-standing type oxygen electrode design, where additional carbon and binders are no longer necessary in the oxygen electrode of Li–O2 battery. A simple and cost effective solvo-thermal techniques was used to fabricate free standing carbon-free electrodes. The highly porous structure of the electrode allows electrolyte and oxygen to diffuse effectively into the catalytic active sites and hence improve the performance. The discharge products would precipitate and decompose on the pores of the free-standing catalyst nanorods. In this study, Mn-based composite oxide was selected as the catalyst candidate and directly deposited on the metallic nickel foam which was applied as the current collector. The electrochemical examination demonstrates that the free-standing electrode without carbon support gives almost the highest cell potential during discharge (2.85 V), the lowest cell potential during charge (3.54 V), almost the highest specific capacity (when considering all active mass in the cathode) and the minimum capacity fading among the rechargeable Li–O2 batteries reported to date. The Li-O2 battery demonstrated cyclability for more than 100 cycles while maintaining a moderate specific capacity of 1000 mAh g-1. Further, the synergistic effect of the fast kinetics of electron transport provided by the free standing structure and the high electro-catalytic activity of the composite oxide enabled the excellent performance of the oxygen electrode for Li-O2 batteries.
Dual-Ion Batteries – Chances for Stationary Energy Storages By Electrode Structuring
Authors: Froböse Linus , Bockholt Henrike , Haselrieder Wolfgang , Kwade Arno 
Published: February 2020

In recent years, energy usage has changed and renewable energy sources are getting more and more important. These green sources (e.g. wind or solar energy) are generated locally but are strongly dependent on current weather conditions. Thus the demand on decentralized large-scale energy storages grows continuously.
In order to fit this market dual-ion batteries offer a high promising technology for stationary energy storage. This system has several benefits compared to the classical lithium-ion battery technology: low cost metal-free active materials, safe and non-toxic electrolytes and an extremely high cycling stability or life time, respectively. Furthermore the opportunity to use water soluble binders and thus cheaper aqueous suspensions in electrode production with a distinct reduction of energy during drying should be noticed.
This work focuses on process engineering aspects and challenges of the electrode production in order to transfer this new battery technology towards technical scale and continuous production processes.
Since particularly ion transport limitations due to large intercalating anions during charge are challenging, specific attention is paid to dual-ion battery electrode structures. Process engineering approaches to compensate these hindrances by optimizing the processing route and the electrode structure will be presented. These improvements result in up to 10 % higher capacities compared to available studies and capacity retentions from over 80 % after 5000 cycles (see figure 1).
The electrode structure is the key factor to support the ion transport for a reliable electrochemical performance. The total diffusion coefficient correlates with the ion mass transport within the electrolyte filled pore structure taking the porosity as well as the tortuosity into account. The presented work includes the determination of these structural parameters via mercury intrusion measurements and points out their contribution to understand transport limitation of large anions and its influence on electrochemical performance.
First Principles Study of Lithium and Oxygen Adsorption on the β-MnO2 (110) Surface
Authors: Ngoepe Phuti Esrom , Maenetja Khomotso P , Mellan Thomas , Catlow C Richard A , Woodley Scott M , Grau-Crespo Ricardo 
Published: February 2020

The Li-air system is a novel battery technology which promises higher specific energy than Li-ion batteries. In this battery the cathode reaction is not the formation of an intercalation compound but the reduction of oxygen gas in the presence of Li+ ions forming lithium peroxide Li2O2 (or LiOH in the aqueous version).1-5 Manganese oxides may also play an important role in this battery: it has been shown that nanostructured MnO2 in different polymorphic states are able to catalyse the formation and decomposition of Li2O2 in the cathode. Understanding the behaviour of the cathode catalysts is the key for improving the function of Li-air batteries.6

The adsorption and co-adsorption of lithium and oxygen at the surface of rutile-like manganese dioxide (β-MnO2), which are important in the context of Li-air batteries, are investigated using density functional theory. In the absence of lithium, the most stable surface of β-MnO2, the (110), adsorbs oxygen in the form of peroxo groups bridging between two manganese cations. Conversely, in the absence of excess oxygen, lithium atoms adsorb on the (110) surface at two different sites, which are both tri-coordinated to surface oxygen anions, and the adsorption always involves the transfer of one electron from the adatom to one of the five-coordinated manganese cations at the surface, creating (formally) Li+ and Mn3+ species. The co-adsorption of lithium and oxygen leads to the formation of a surface oxide, involving the dissociation of the O2 molecule, where the O adatoms saturate the coordination of surface Mn cations and also bind to the Li adatoms. This process is energetically more favourable than the formation of gas-phase lithium peroxide (Li2O2) monomers, but less favourable than the formation of Li2O2 bulk. These results suggest that the presence of β-MnO2 in the cathode of a non-aqueous Li-O2battery lowers the energy for the initial reduction of oxygen during cell discharge.
1. M. Armand and J. M. Tarascon, Nature, 2008, 451, 652-657.
2. P. G. Bruce, S. A. Freunberger, L. J. Hardwick and J.-M. Tarascon, Nature materials, 2011,

11, 19-29.
3. K. Abraham and Z. Jiang, Journal of The Electrochemical Society, 1996, 143, 1-5.
4. R. Black, B. Adams and L. Nazar, Advanced Energy Materials, 2012, 2, 801-815.
5. J. Christensen, P. Albertus, R. S. Sanchez-Carrera, T. Lohmann, B. Kozinsky, R. Liedtke, J.
Ahmed and A. Kojic, Journal of The Electrochemical Society, 2011, 159, R1-R30.
6. Y. Shao, S. Park, J. Xiao, J.-G. Zhang, Y. Wang and J. Liu, ACS Catalysis, 2012, 2, 844-857.
Electronic and Morphological Characterization of Nanostructured Ni-Doped (Ce,Gd)O2-δ Anodes for IT-SOFCs
Authors: Fernandez Zuvich Afra , Soldati Analía , Larrondo Susana , Saleta Martín , Lamas Diego German , Baqué Laura Cecilia , Caneiro Alberto , Serquis Adriana 
Published: February 2020

It is well known that CeO2-based materials present excellent catalytic properties for the oxidation of H2 and CH4 fuels [1] and with the incorporation of metal oxides (Gd2O3, Sm2O3, Y2O3) in the CeO2 lattice the oxygen storage capacity, the ionic conductivity and the specific surface area can be significantly improved. Furthermore, the addition of metals such as Ni or Cu enhances the electronic conductivity of the material, thus enabling them as efficient IT-SOFC anodes [2, 3].
A previous study on the microstructure influence in the electrochemical properties of commercial Ce0.9Gd0.1O1.95 (GDC) with several grain sizes, impregnated with NiO [3] to form 40:60 (%wt) composites showed that better performances were achieved with nanocrystalline samples supporting the fact that the optimization of microstructure and morphology are crucial for the development of efficient anodes.
A particular approach to optimize the anode microstructure is to tailor its porosity. In this way, the addition of activated carbon in an intermediate step followed by calcination at 1450ºC resulted in an increase of more than 30% in the anode efficiency [4]. Other composite morphologies can be obtained modifying the way that Ni is incorporated into the material. A common procedure is the impregnation method: the GDC material is submerged in a Ni(NO3)2*6H2O solution, dried in an oven at 90ºC and calcinated at 350ºC to generate NiO [4].
In this work, we present a new modified sol-gel method to incorporate Ni into the precursor solution. This route produces a powder with a very homogeneous Ni distribution. Transmission Electron Microscopy (TEM) and Energy Dispersive Spectroscopy (EDS) analysis indicated that this modification resulted in smaller particle sizes with a narrower size-distribution than the observed in commercial Ni-GDC cermets.
The study of the oxidation state and coordination of Ce and Ni in these cermets, simulating in-operando conditions, was performed using synchrotron DXAS technique.
Electrochemical impedance spectroscopy (EIS) analyses allowed to establish a correlation between the electrochemical properties with the sample´s characteristics (microstructure, Ni distribution, etc.).
[1] M.G. Zimicz, S.A. Larrondo, R.J. Prado and D.G. Lamas, Int. Journal of Hydrogen Energy 37 (2012) 14881–14886.
[2] W.C. Chueh, Y. Hao, W. Jung and S.M. Haile, Nature Materials 11 (2012) 155-161.
[3] M. G. Zimicz, P. Núñez, J. C. Ruiz-Morales, D. G. Lamas, S. A. Larrondo, Journal of Power Sources, vol. 238 (2013) 87-94
[4] A. Fernandez Zuvich, A. Caneiro, C. Cotaro and A, Serquis. Procedia Materials Science 1 (2012) 628-635.
Effect of Cation Demixing on the Electrochemical Performance of LSCFO Cathodes for SOFCs
Authors: Baqué Laura Cecilia , Soldati Analía , Troiani Horacio , Serquis Adriana 
Published: February 2020

Hydrogen along with renewable energy resources are planned to replace fossil fuels in the near future. Solid Oxide Fuel Cells (SOFCs) are an attractive solution for the transition period between both energy sources since they can operate by using not only hydrogen but also fossil fuels. Nevertheless, the commercialization of these devices is still hindered by their cost and long term degradation. Overall cell degradation depends on the degradation of its main components: anode, electrolyte and cathode.
The use of mixed conducting cathodes such as La1-xSrxCo1-yFeyO3 (LSCFO) improves considerably the performance of the cell. However, one of the most common degradation mechanisms of LSCF reported in the literature is the segregation of Sr.
This work aims at studying the effect of Sr segregation on the electrochemical properties of LSCFO cathodes. LSCFO oxide powders were prepared by solid state reaction and deposited on Ce1-xGdxO2 electrolytes by spin coating. Afterwards, these cells were heat treated at conditions that facilitate the formation of Sr segregates. The electrochemical properties of the cathodes were monitored by electrochemical impedance spectroscopy, while the microstructure was characterized by Scanning Electron Microscopy, Transmission Electron Microscopy, Energy Dispersive Spectroscopy, and X-Ray Diffraction. The relation between the Sr segregation phenomena and the changes in the electrochemical performance of the cathode is discussed.
Invited: Coatings for Robust Metal Bipolar Plates
Authors: Wang Conghua , Tao Yong 
Published: February 2020

Metal bipolar plates have advantages of lighter weight and smaller volume over graphite based bipolar plates for automobile fuel cell stacks. Stainless steel has been identified as the primary candidate of the substrate. It has reasonable corrosion resistant, high electrical and thermal conductivity, suitable mechanical properties and formability to form the proper flow field by conventional high speed stamping process. The most important, SS foil is widely commercially available and used in various markets, which result in its low cost comparing with other corrosion resistant alloys.
Additional treatment on stainless steel is necessary for three reasons. First is to reduce the surface electrical contact resistance with gas diffusion layer. The second is to further improve the corrosion resistance of stainless steel in PEM fuel cell stack operation conditions, especially under the transient high voltage conditions. The third is to minimize the absorption of leached ions on the electrode catalyst that may poison electrodes.
Two types of coatings have been investigated. One is the coating using precious metal, the other is precious metal free coating technologies. The advantages and progresses of each coating will be reviewed.
TreadStone has been involved in corrosion resistant metal plate development for several years. A unique design of metal plate coating and its low cost fabrication technology have been developed. It has demonstrated stable long term (2,000 hours) operation for automobile fuel cell stacks under dynamic operation conditions. More development activites are on-going to further reduce the cost with the supports from US Department of Energy.
Interlocking Membrane/Catalyst Layer interface for High Mechanical Robustness of Hydrocarbon Membrane Based PEMFC
Authors: Kim Hee-tak , Park Jung-Ki , Choo Min-Ju , Oh Keun-Hwan 
Published: February 2020

For decades, the use of hydrocarbon ionomers in PEMFCs has been constantly attempted as a membrane to replace the commonly used perfluorinated ionomers to lower costs, raise fuel efficiency, and enable easier manufacturing of membrane electrode assembly (MEA). Examples include sulfonated poly(arylene ether sulfone)(s-PAES), sulfonated poly(ether ether ketone) (s-PEEK), and sulfonated polyimide (s-PI). However, when a hydrocarbon membrane is assembled with catalyst layers (CLs) based on a perfluorinated ionomer, a problem of interfacial delamination between the membrane and the CL is often encountered. Due to the poor interface between hydrocarbon ionomer based membrane and perfluorinated ionomer based catalyst layer, in many cases, opportunities to be employed in PEMFC have been denied.To address this problem, hydrocarbon ionomers having chemical structures similar to those of the membrane have been introduced as proton conducting polymer electrolytes into CL. However, due to the low oxygen permeability of the hydrocarbon ionomers, the corresponding CL showed a relatively low power performance. Although such tight interfacial bonding for hydrocarbon membranes has been urgently requested, the problem still remains unsolved.
Here, we propose an interlocking interface structure for providing a tight interfacial bonding between hydrocarbon membrane and perfluorinated ionomer based CL, turning away from the previous focus on chemical modification and physical roughening. This approach is based on a friction force generated due to a difference in volume expansion between the two polymers in an interlocked architecture. The interlocked interface of sulfonated poly(ether ether ketone) and Nafion based CL were realized and evaluated. A profound improvement in interfacial bonding strength was observed with the interlocked architecture. Also, under accelerated stress conditions, interfacial bonding was better maintained with the interlocked interface. The physical interlocking strategy could provide an oppotunity for a lot of hydrocarbon membrane suffering from poor interfacial adhesion to be used in PEMFC.
Preparation of a Carbon-Based Non-Precious Metal Catalyst Fehmta/C for Oxygen Reduction Reaction
Authors: Xiong Zhongping , Si Yujun 
Published: February 2020

A non-precious metal catalyst for oxygen reduction reaction was prepared by a simple method and using cheap materials. The basic steps include: 0.40g of FeCl3.6H2O was dissolved in 5 ml ethanol, and then the solution was uniformly mixed with 0.5g of acetylene black. The obtained mixture was dried at 50℃ and was mechanically ground with 0.5g of hexamethylenetetramine for 30 minutes. Then the precursor was heat-treated at 700℃ for 2 hours under nitrogen atmosphere and a catalyst named FeHMTA/C was got. Figure 1 shows the ORR catalytic activities of acetylene black and FeHMTA/C catalyst. It can be seen that the untreated acetylene black has not ORR activity. However, there is an obvious reduction process with an onset reduction potential of 0.56V (vs. SCE) in the voltammogram of FeHMTA/C catalyst as shown in Figure1(c). This process corresponds to the oxygen reduction reaction, which shows the FeHMTA/C catalyst has good ORR activity.

Acknowledgments

This work was supported by the Specialized Research Fund for the Doctoral Program of Sichuan University of Science and Engineering (No. 2012RC16) and the Opening Project of Key Laboratory of Green Catalysis of Sichuan Institutes of High Education (No. LYJ1206, LYJ1401).
Figure 1 Linear sweep voltammograms of (a) acetylene black and (c) FeHMTA/C catalyst in 0.5M H2SO4 solution saturated by O2, and (b) FeHMTA/C catalyst in 0.5M H2SO4 solution saturated by N2
.