bluuebunny/crossref_metadata_2025_split huggingface dataset:
First-Principles Study of the Thermodynamic Stability of Sodium Oxides As a Function of Temperature, Pressure and Particle Size; And Its Implications for Na−O2
Batteries
Authors: Kang ShinYoung , Mo Yifei , Ong Shyue Ping , Ceder Gerbrand 
Published: February 2020

Recently, Na−O2 batteries have shown their potential as a high energy density electrical storage. Unlike Li−O2 batteries that have only one discharge product, Li2O2, the Na−O2 battery system has three potential discharge products: Na2O, Na2O2 and NaO2. Recent experiments observed either Na2O2 or NaO2 as a discharge product, and the performance of Na−O2 batteries is undoubtedly influenced by which particular discharge product is formed.[1-4] We investigated the thermodynamic stability of each phase as a function of temperature, O2 partial pressure, and particle size using first-principles calculations. Our results reveal that in bulk Na2O2 is the stable phase at the standard state (300 K, 1 atm) in agreement with experiments. Bulk NaO2 can only be formed at PO2 > 8.5 atm and/or T < 230 K (FIG. 1), both of which are unlikely to be accessed during the operation of typical Na−O2 batteries. To understand the relative stability of these two competing compounds at the nanoscale, we calculated their surface energies and found that the lowest surface energies of Na2O2 are in the range of 30−45 meV/Å2, while that of NaO2 is only 12 meV/Å2, rendering the possibility of stabilization of NaO2 over Na2O2 at the nanoscale. To confirm this idea, we constructed the phase diagram of Na2O2 and NaO2 as a function of particle size in FIG. 2. Indeed, the low surface energies of NaO2 stabilizes NaO2 nanoparticles, for example, up to 3 nm at PO2 = 0.1 atm. Moreover, we found that the nucleation energy barrier for NaO2 nanoparticles is much smaller than that of Na2O2, particularly when there is a small discharge overpotential and/or enough O2 supply. We expect our findings to direct efforts towards understanding and controlling the formation of desired Na−O compounds in battery operation, and furthermore invigorate interest on the potential of Na−O2 batteries.[5]

References

[1] P. Hartmann, C. L. Bender, M. Vracar, A. K. Durr, A. Garsuch, J. Janek, and P. Adelhelm, Nat Mater 12, 228 (2013).
[2] Q. Sun, Y. Yang, and Z.-W. Fu, Electrochemistry Communications 16, 22 (2012).
[3] S. K. Das, S. Xu, and L. A. Archer, Electrochemistry Communications 27, 59 (2013).
[4] J. Kim, H.-D. Lim, H. Gwon, and K. Kang, Physical Chemistry Chemical Physics 15, 3623 (2013).
[5] S. Kang, Y. Mo, S. P. Ong, and G. Ceder, Nano Letters 14, 1016 (2014).
Fully Fluorine-Free Liquid Electrolytes for Na-Ion Applications
Authors: Michalczewski Krystian , Bitner-Michalska Anna , Gajewska Agnieszka , Poterala Marcin , Dranka Maciej , Zukowska Grazyna Zofia , Kalita Michal Jan , Marcinek Marek 
Published: February 2020

Sodium-based batteries are interesting candidates, when replacement of the lithium- and lead-based batteries ins taken into consideration. The advantages over lead-based systems is based mainly on the low weight and low impact on the environment of the sodium in comparison to lead. Therefore, use of the sodium-based batteries is interesting when high power density is needed. The main advantage of sodium in comparison to lithium is based on the fact that sodium is both the most abundant alkali metal on Earth. It is worth to remember that application of the Li-ion technology in stationary batteries applications and in the electric vehicles industry is limited due to insufficient sources of lithium. Such problems in case of sodium-based batteries do not occur. Moreover, sodium salts are much cheaper than respective lithium salts.
Up to now, several sodium-based batteries were constructed. First sodium-sulfur battery, unfortunately, exhibiting low energy density, was built in 1960s. This technology was developed and NASICON electrolyte was introduced to it in 2000s. This battery was of superior energy density. On the other hand, both electrodes need to be liquid in such system. Therefore, the operating temperature of such battery have to be higher than 150°C, and the electrode materials in it need to be melted before it starts. This make impossible use of such batteries in applications in which fast start is desired. The same disadvantage has Na-NiCl2 battery, which also exhibit low energy density.
It is believed that the problems of the high operating temperatures for sodium-based systems can be solved by designing of sodium-ion power sources, per analogiam to the lithium-ion battery technology. The main problem related to this system is to design and obtain the electrolyte which is stable against electrode materials. Naturally, the problems of the Na-ion are similar to this of lithium-ion, however, several novel issues occur. The affinity of the sodium to the fluoride is higher than to lithium, therefore, the decomposition of the salt is more intensive. There are also differences when the affinity of lithium and sodium to the solvent molecules is discussed. Due to this, the simple substitution of the lithium salts with the sodium ones can give not fully sufficient results. Therefore, new electrolytes, containing novel salts and solvents other than carbonates, need to be tested in such systems.
In the presentation, the ion transport properties of the systems containing novel sodium salts with heteroaromatic anion will be presented. The electrochemical properties of the electrolytes will be confronted with the coordinating properties of both cation and anion in the solution and in the solid-state. Also interactions in the salt solvates will be discussed.
NiO/YSZ Reduction for SOFC/SOEC Studied In Situ by Environmental Transmission Electron Microscopy
Authors: Simonsen Søren Bredmose , Agersted Karsten , Hansen Karin Vels , Jacobsen Torben , Wagner Jakob Birkedal , Hansen Thomas Willum , Kuhn Luise Theil 
Published: February 2020

SOFCs/SOECs are typically composed of ceramic materials, which are highly complex at the nano-scale. Scanning and transmission electron microscopy (SEM and TEM) are routinely applied for studying these nano-scaled structures post mortem, but only few SOFC/SOEC studies have applied environmental TEM (ETEM). ETEM offer the possibility to record image series (movies) of the ceramic nanostructures with atomic scale resolution during exposure to a reactive gas environment at elevated temperatures. The present contribution focuses on the typical reduction preparation step for the state-of-the-art Ni/YSZ (YSZ = Y2O3-stabilized ZrO2) based anodes for SOFC and cathodes for SOEC. Specifically, the reduction of nickel oxide to form the catalytically active nickel surface is monitored directly at the nano- and atomic scale by using an ETEM. The reduction process was followed while exposing NiO/YSZ and pure NiO to H2 at temperatures from room temperature to ca. 800°C. The NiO/YSZ was prepared by crushing down a tape casted and sintered model anode/cathode into a fine powder. Previous studies based on averaging techniques have shown that the reduction of pure NiO is a relatively rapid process, while the reduction of NiO/YSZ is slower, which indicates that the presence of YSZ inhibits the reduction of NiO. In the presents in situ experiments the temperature dependent reduction profile are found similar for the both nano-scaled NiO and NiO/YSZ sample. The apparent inhibitive effect of YSZ on NiO reduction is therefore not caused by a direct interaction between NiO and YSZ, but is an indirect effect depending on the NiO being integrated in a macroscopic network of NiO/YSZ. A Titan E-Cell 80-300ST TEM was used for the in situ work in combination with the chip-based heating holder from Protochips which facilitated rapid temperature ramping for example from room temperature to 800°C in only 1 s. The ETEM results are compared to complementary averaging techniques such as thermo-gravimetric analysis (TGA) and X-ray diffraction analysis (XRD).
The figure presents a TEM image series of NiO during exposure to 2 mbar H2 and constant temperature ramping rate of 1°C/min. The NiO observed in the first image at 320°C is dense. From the lower left corner a front of porous Ni is progressing until full reduction at 340°C.
Thermally Robust Thin-Film SOFCs for Mobile Application
Authors: Kim Kun Joong , Park Byung Hyun , Choi Gyeong Man 
Published: February 2020

Metal-supported solid oxide fuel cell (MS-SOFC) is promising for use at intermediate temperature range (500-700°C) since metal could provide the good thermal conductivity and the mechanical strength in addition to the low cost. The MS-SOFCs are often fabricated by co-firing in reducing atmosphere to avoid metal oxidation. However, the inter-diffusion between Fe/Cr in stainless steel (STS) and Ni in the conventional cermet anode is detrimental to the electrochemical performance of the cell. In this study, a multi-layered cell consisting of a yttria-stabilized zirconia (YSZ) electrolyte, and a porous anode layer, and a ferritic STS support, was fabricated using tape casting and co-firing process.
The cell with alternative anode was compared with that with conventional anode in terms of microstructure, Cr poisoning, and thus anodic performance. It was found that the use of diffusion barrier layer (DBL) reduces the reaction between conventional Ni-cermet anode and STS and provides a stable performance. The performance can be further enhanced with an alternative anode.
Invited: Corrugated Cell Structures in Membrane Electrode Assemblies
Authors: Grot Stephen 
Published: February 2020

The traditional Proton Exchange membrane fuel cell stack with its bipolar plates with grooved flow channels,
flat membrane electrode assemblies (MEAs), seals and end-plates has been the dominant
method of construction of multi kW fuel cells for the past 40 years. Smaller sub-watt and
portable applications have explored novel cell design variations such as “jelly roll”
concepts but none have been able to achieve the power density of the traditional
stacked plate design. The primary reason for this is the efficient collection of the current
and the compact packing of the MEAs.
However at the present time one of the most challenging aspects of traditional PEM fuel
cell stacks is the difficulty to achieve the platinum catalyst utilization target of 0.2 g
Pt/kWe set forth by DOE. Good catalyst utilization can be achieved with state-of-theart
catalyst coated membranes (CCM) when ultra-low catalyst loadings (< 0.1 mg/cm2)
are used at lower current. Unfortunately when ultra-low loadings are used, the peak
power density is lower as compared to conventional loadings. Thus a larger total
active area and a larger bipolar plate is needed which results in a lower overall stack
power density and as such the DOE targets of power density can not be achieved
simultaneously
We thus now introduce in this proposal, our novel concept to increase the available MEA
active area by 2x or more while maintaining the same bipolar plate size. This is
achieved via a corrugated MEA sandwiched between bipolar plates. This is much like
corrugated cardboard, where the center corrugation (or flute) is the MEA. The
corrugations then form the gas channels thus there is no need for forming flow field
channels in the bipolar plates. Thus the gas diffusion media as well as the membrane needs to be formed in the corrugated structure. We will describe the state of our development on this approach.
An Optimization Study of Nafion-1,2,3-Triazole - H3PO4 Composite Membrane for High Temperature- Non Humidity Condition of PEMFC
Authors: Jun Mun-Suk , Ghil Lee-Jin , KIM Je-Deok 
Published: February 2020

The proton exchange membrane fuel cells (PEMFCs) are receiving increasing attention as one of the clean energy and suitable primary power sources for transportation and stationary applications. The proton exchange membrane of recent PEMFCs is commonly used perfluorosulfonic acid polymer membranes (e.g., Nafion). This polymeric membrane is depend on the presence of water to solvate the protons from the sulfonic acid groups. Consequently, the operational cell temperature is limited to below 100oC. However, the PEMFC when operating at high temperature (above 120oC) is having numerous advantages because include increased reaction kinetics, easier water management and a better tolerance to CO.
In this study, we examined Nafion-based composite membrane that can be used at high temperature and non-humidity condition. A novel Nafion-based composite membrane with 1,2,3-triazole and phosphoric acid was prepared by autoclave solution processing [1-3]. Nafion-1,2,3-triazole-H3PO4 (Na-Tri-PA) composite membranes were used as an electrolyte membrane for PEMFC at non-humidity condition of 150oC. Here, we obtained homogeneous membrane as adding 1,2,3-triazole in the Na-PA membrane, and from an optimization process for MEA, Na-Tri-PA composite membrane showed the power density of about 70mW/cm2.
Acknowledgements
This work was partially supported by MEXT program for development of environmental technology using nanotechnology.
[1] J. –D. Kim, M. –S. Jun, C. Nishimura, Y. –W. Choi, ECS transactions, 35, 241 (2011).
[2] J.-D. Kim, A. Suzuki, M.-S. Jun, ECS transactions, 58, 1185 (2013).
[3] M.-S. Jun, J.-D. Kim, ECS transactions, 58, 1195 (2013).
Cross-Linked Anion Exchange Membranes for AEMFC
Authors: Amel Alina , Hickner Michael , Ein Eli Yair 
Published: February 2020

Anion-exchange membranes (AEMs) have attracted great interest for their operation in alkaline platinum-free fuel cells .However the use of AEMs in a wide range of devices has been limited due to various challenges. Two major obstacles are the membranes' low conductivity and poor stability in the highly alkaline environment required for fuel cells that necessitates generation of hydroxide anions and transport through the solid polymer membrane.
The effect of cross-linker and its apparent impact on AEM properties will be the focus of this study. Two different cross-linkers were chosen, one has an amino-ether group and the other, has a trymethylhexadecyl amine group. These two crosslinkers have a fundamental difference, where the amino-ether is more hydrophilic and therefore would improve membrane's conductivity and may prevent membrane’s drying out. The properties and stability of the membrane with these two cross-linkers were investigated. Conductivity and swelling measurments were examined at various temperatures for both types of samples. Indeed, water uptake and conductivity were found to be higher for the amino-ether crosslinker. However, degradation measurements analyzed by FTIR and XPS, indicated that the membrane cross-linked by amino-ether group degraded faster at high temperature and pH conditions. Thus, the ether linkage in the cross-linker has a negative influence on the thermal and alkaline stability of the membrane.
Gas-Diffusion and Direct Electron Transfer-Type Bioanode for Hydrogen Oxidation with Oxygen-Tolerant [Nife]-Hydrogenase As an Electrocatalyst
Authors: Kano Kenji 
Published: February 2020

In order to realize the promising hydrogen energy conversion system, a superior catalyst to oxidize hydrogen is needed.Nowadays, the power devices such as an H2/O2 fuel cell rely on platinum as a catalyst, which is a rare metal and thus too expensive. Many researchers have explored alternative catalysts. From the aspect of bioelectrochemistry, hydrogenase that catalyzes the redox reaction between hydrogen and proton have received a lot of attention, and the bioelectrocatalytic properties has extensively been characterized all over the world.
The discovery of O2- and CO-tolerant [NiFe]-hydrogenase is one of the breakthroughs essential for the construction of the aforementioned biofuel cell, and the unique properties have been investigated from several viewpoints. One critical problem in utilization of [NiFe]-hydrogenase is reversible inactivation caused by the anaerobic oxidation at high electrode potential or high solution potential. Several spectroscopic studies have revealed that the catalytic cycle proceeds in three states: Ni-SI (active silent form), Ni-R (H2-reduced form), Ni-C (one-electron oxidized form of Ni-R), and that the inactivation generates a Ni(III) state form known as Ni-B by one-electron oxidation of Ni-SI, in which a hydroxide ligand is coordinated to the Ni atom in a bridging position with respect to the Fe(II).
A membrane-bound [NiFe]-hydrogenase (MBH) from Hydrogenoviblio marinus allows a direct electron transfer (DET)-type bioelectrocatalysis for the H2 oxidation and is an O2-tolerant promising enzyme for the construction of enzymatic H2/O2 biofuel cells.
From the practical viewpoint of the electricity production, the H2 depletion near the electrode surface and the oxidative and reversible inactivation (as a competitive inhibition) of [NiFe]-hydrogenases limit the H2 oxidation, and consequently causes the power decline. In this research, the Michaelis constant has been evaluated as 0.57 mM under steady-state conditions for the DET-type H2 oxidation by MBH chemically immobilized on Ketjien black mesoporous carbon electrode. In order to spontaneously supply H2 from the gas phase and to avoid the inactivation, an MBH-adsorbed gas-diffusion-type electrode has been constructed. The maximum current density of H2 oxidation has reached about 6 mA cm-
2 at 0 V (vs. Ag|AgCl|sat. KCl electrode) under quiescent (passive) and H2 atmospheric conditions.
Characterization of the Electron Transport Chain Metabolon Bioelectrocatalysis
Authors: Pelster Lindsey , Minteer Shelley D. 
Published: February 2020

The electron transport chain is a group of membrane redox enzymes that are the driving force for the production of energy in mitochondria. Several theories and models have circulated different structures of the enzymes in the inner membrane.1 The three enzyme complexes form a supercomplex or respirasome, where Complex I, dimer Complex III, and various copies of Complex IV are electrostatically, hydrophobically and catalytically connected. While structural, kinetic, and genetic evidence prove the formation of the supercomplex, characterization of the bioelectrocatalysis has never been attempted of the three enzymes together on an electrode.2 The supercomplex contains multiple redox cofactors of the individual complex that span the lipid membrane and can come in contact with the electrode surface. By purifying the electron transport chain supercomplex, we have been able to reconstruct the inner membrane and immobilizing it onto a gold electrode. A polymer tethered lipid bilayer allows for the study of the natural bioelectrocatalysis of the large transmembrane proteins. With the addition of oxidized cytochrome c, Complex IV gives a catalytic response indicating that Complex III and Complex IV are active. With the addition of NADH and oxidized cytochrome c, the catalytic peaks increase. This indicates that all three enzymes are working together increasing their redox activities at the surface of the electrode. The supercomplex is further confirmed by inhibition of CIII and CIV, eliminating all activity of the enzymes at the electrode surface. This evidence shows how dependent the enzymes are on each other for efficient catalytic activity. The characterization of the supercomplex of these transmembrane redox enzymes and their bioelectrocatalysis on the electrode is the first for studying a natural metabolon electrochemically.
References
1. Hackenbrock, C. R.; Chazotte, B.; Gupte, S. S., The random collision model and a critical assessment of diffusion and collision in mitochondrial electron transport. J Bioenerg Biomembr
1986,
18 (5), 331-368.
2. (a) Genova, M. L.; Lenaz, G., Functional role of mitochondrial respiratory supercomplexes. Biochimica et Biophysica Acta (BBA) - Bioenergetics
2014,
1837 (4), 427-443; (b) Genova, M. L.; Baracca, A.; Biondi, A.; Casalena, G.; Faccioli, M.; Falasca, A. I.; Formiggini, G.; Sgarbi, G.; Solaini, G.; Lenaz, G., Is supercomplex organization of the respiratory chain required for optimal electron transfer activity? Biochimica et Biophysica Acta (BBA) - Bioenergetics
2008,
1777 (7-8), 740-746.
Effect of Humic Acid on the Electrochemical Performance of Microbial Fuel Cells (MFCs)
Authors: Rodriguez Valadez Francisco Javier , Gonzalez Nava Catalina 
Published: February 2020

Microbial fuel cell (MFC) are bioelectrochemical system using exoelectrogenic microorganisms to produce electricity, electrons are transferred through a biofilm growth on the anode surface (Sund et al., 2007), the humic acid had optimal biofilm formation, reducing the lag-time and improve the performance of the MFCs. The aim of this work was to evaluate the effect of humic acid addition on the performance of MFC. The biofilm growth with and without humic acid was evaluated by cyclic voltammetry (CV), chronopotentiometry at open circuit potential and scanning electron microscopy (SEM), the performance of MFC was evaluated by polarization curves and values of voltage, current density and power density achieved with data acquisition system. Triplicate measurements made in a MFC with two chambers of 375 mL, carbon cloth electrodes and proton exchange membrane. From the 5th day, the MFC without humic acid showed a voltage of 0.1 V in response to biofilm wrowth and a steady voltage of 0.34 V after 40 days, cyclic voltammetry showed reduction signs in -0.284 to 0.259 V Vs SHE and oxidation signs in -0.643 to 0.060 V Vs SHE, showing electroactivity biofilms. Optimal biofilm formed reduce the internal resistance from 50 to 4.5 kµÙ, also the anode potential changed from -0.251 to -0.512 V Vs SHE for better performance of MFC. The MFC showed a maximum power density of 1.78E-03 W/m2, current density of 3.6 mA/m2 and power density of 1.4 W/m2. The optimal biofilm formation is important for the performance of MFCs (Martin et al., 2013) and humic acid had effect on the electrode surface supported the growth of biofilm due to functional groups with redox properties (Wandruszka Palmer, 2010).

References

Sund et al., 2007. Appl Microbiol Biotechnol. 76, 561-568.
Palmer y Wandruszka, 2010. Environmental Science & Pollution Research. 17, 1362-1370.
Martin et al., 2013. J. Appl. Electrochem. DOI 10.1007/510800-013-0537-2.
Theoretical Analysis of Surface Waves: Revisited
Authors: Yamamoto Masahiro , Kano Kenji 
Published: February 2020

The surface wave for the strongly adsorbed redox spices on electrode is one of the fundamental electrochemical issues, because we don’t need considering the mass transfer of redox species and can calculate voltammogram easily. The ideal voltammogram of the surface wave is symmetric for the forward and the backward scan and it is well known the full-width-at-the-half-maximum (FWHM) is 91 mV.
Recently Nieh et al. proposed the potentiometric coulometry based on charge accumulation with a peroxidase/osmium polymer-immobilized electrode for sensitive determination of hydrogen peroxide [1]. In this potentiometric coulometry the peak shape and width of the surface wave is the key point to get the amount of the hydrogen peroxide in the polymer film. Kakutati and Senda [2] and Laviron [3] showed that the interaction between the adsorbed redox species change the FWHM of the surface wave, i.e. the FWHM is decreased (increased) when e(O-O) + e(R-R) – 2e(O-R) < 0 (> 0).
In this study we have reformulated the chemical potential of the interacting redox species based on Bragg-Williams and Bethe-Guggenheim approximation, and the surface wave voltammogram is evaluated. For the attractive interaction we have found the limiting case that the FWHM become almost zero and the current diverges.　In the Monte Carlo simulation for Kawasaki dynamics system we have confirmed chemical potential obtained by the Bethe-Guggenheim approximation is good enough approximation for the nearest-neighbor interaction model.
We also proposed that the asymmetry of surface wave voltammogram is due to the counter-ion binding interaction for the redox species.
References
[1] C.-H. Nieh et al. Electrochemistry Communications 33 (2013) 135-137.
[2] T. Kakutani and M. Senda, Bull. Chem. Soc. Japan 52 (1979) 3236-3241.
[3] E. Laviron, J. Electroanal. Chem. 100 (1979) 263-270.