bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydroxide Transport in Next Generation Anion Exchange Membranes
Authors: Sarode Himanshu N , Pandey Tara P , Yang Yuan , Knauss Daniel M , Coughlin E. Bryan , Liberatore Matthew W , Herring Andrew M 
Published: February 2020

The potential of anion exchange membrane (AEM) fuel cells/electrolyzers and other devices to provide inexpensive compact power from a wider variety of fuels than is possible with a proton exchange membrane (PEM) fuel cell, has continued to drive the research interest in this area. Alkaline catalysis in fuel cells has been demonstrated with non-precious metal catalysts, and with a variety of fuels beyond H2and methanol. Alkaline fuel cells (AFCs), based on aqueous solutions of KOH, have serious drawbacks associated with system complexity and carbonate formation. AEM fuel cells have a number of advantages over both PEM fuel cells and traditional AFCs; however, although anionic conductivity in AEMs can be comparable to PEMs the chemical stability of membrane attached cations in hydroxide is still not always sufficient for practical applications. The real issue though, is water transport; water is both a product and a reactant in these systems, and wet cations are much more stable than dry. So an understanding of water in these membranes is essential.
Recenetly we have fabricated a series of membrnes with sufficent stability that we are able to measure the hydroxide conductivity in them at elevted temperatures while being humidified. Here we discuss water and hydroxide transport in a series of thin mechanically robust state of the art experimental AEMs. The membranes are generally constructed from an isoprene or ethylene block and a vinyl benzyl bromide block, either randomly or in di-, tri- or penta- block configurations. Post quaternization leads to functionalized AEMs. We use electrochemical impedance spectroscopy to measure anion conductivity, multi-nuclear pulse field gradient spin echo NMR to measure self-diffusion, and broadband electric spectroscopy to measure the relaxation processes in these polymers. This information is coupled with microscopy and SAXS to explore the polymer morphology. Putting transport and morphology together allows us to describe a complete picture of water and anion transport in these systems.
Molecular Simulation of Oxygen Solubility and Diffusivity in Ionomer on Pt Surface
Authors: Kurihara Yuya , Mabuchi Takuya , Tokumasu Takashi 
Published: February 2020

Polymer electrolyte fuel cell (PEFC) is focused as a next-generation energy conversion system because of a high efficiency and a low environmental load. In the cathodic catalyst layer, there are Pt catalysts on supported carbon microparticles, and those particles are covered with ionomer films composed of polymer electrolytes, hydronium ions and water molecules. The ionomer has two properties for the water-generating reactions in the cathodic catalyst layer: the proton conductivity and the oxygen permeability. In particular, the dependence of the oxygen permeability on water content has not been clear.
In this study, we analyzed the oxygen permeability in the ionomer on the Pt surface using molecular dynamics simulations. At first, we constructed the system of the ionomer on the Pt surface, and then we set the gas oxygen molecules above the ionomer, and let the molecules permeate through the ionomer by the pressure gradient as shown in Fig. 1. Using this system, we calculated the oxygen solubility and the oxygen pathways in each region: the ionomer/gas interface, the bulk region, the ionomer/Pt interface. In general, the oxygen permeability is evaluated by the product of the oxygen solubility and the oxygen diffusivity. Thus, we calculated the oxygen solubility of each region in the ionomer at different water contents. As a result, the solubilities of all regions tend to decrease as water content increases. Moreover, we evaluated the oxygen pathways in the ionomer to evaluate the oxygen diffusivity, and the result shows that oxygen prefers the surface of hydrophilic regions to the hydrophobic regions. In experimental data, the diffusion coefficient of oxygen in a dry membrane is smaller than that of oxygen in bulk water. Therefore, the dependence of oxygen diffusivity on water content was estimated by calculating the ratio of the number of oxygen molecules in the hydrophilic region to that in the hydrophobic region.

Figure 1
Effects of Water Structure on Proton Transport in Nafion Thin Films with Molecular Dynamics Simulations
Authors: Aochi Joji , Mabuchi Takuya , Tokumasu Takashi 
Published: February 2020

Polymer electrolyte fuel cell (PEFC) is expected to play important roles for next generation power systems in terms of high efficiency and low environmental burden and capability for emergency use, but there are still many hurdles to be largely commercialized. One of them results from problems in catalyst layers (CL). What required for CL is, for example, reducing the amount of Pt particles with keeping high current density. To accomplish this, knowledge about optimum structures of CL based on material transport properties is needed because there is a strong correlation between current density and transport properties. Although there are many reports about material transport properties in the polymer electrolyte membrane (PEM), it is predicted that material transport properties in CL show some unique characteristics because of effects of interfaces in CL. It means that the knowledge obtained from PEM should not be applied to CL. In addition, the researches about CL have been tried by means of experiments and simulations, but especially the transport properties have not been clarified yet. There are nanoscopic structures in Nafion thin films and it is hard to capture the transport phenomena in such a small area by experiments and macroscopic simulations.

In this study, we analyze proton transport properties in the cathode CL using molecular dynamics simulations, focusing on the dependences of the diffusion coefficient on water content. We consider the proton transport mechanism as a combination of the Vehicular mechanism and the Grotthuss mechanism. The Grotthuss mechanism is represented using empirical valence bond methods. It has been shown by previous researches in PEM that the Grotthuss mechanism is a dominant factor for proton diffusion in relatively high water contents. Thus, it is essential to consider the Grotthuss mechanism for analysis of proton transport in CL as well. The system consists of graphite surface and Nafion thin films. Pt particles are neglected because of a restriction of calculation cost. In PEM analysis, the diffusion coefficient of protons increases with increasing water contents. First, we report whether the same trend as observed in PEM can be seen in CL and the correlation between diffusibility and structures. Next, unique characteristics of proton transport properties in CL compared to the PEM analysis are reported. They are evaluated in terms of mass distribution of the thin films and solvent molecules. From this analysis, it is found that the diffusibility is not much affected by surface because of a lack of solvent molecules on surface, which is attributed to the hydrophobic properties of graphite.
Design and Luminescent Properties of Ce3+-Activated Oxide Phosphor
Authors: Kim Sun Woog , Hasegawa Takuya , Muto Masaru , Kawano Yukari , Uematsu Kazuyoshi , Toda Kenji , Takaba Hiromitsu , Ishigaki Tadashi , Sato Mineo 
Published: February 2020

Ce3+ ion has been usually used as an activator in the white LEDs phosphor because Ce3+-activated phosphors have a strong optical absorption at wide light region from UV to blue light and exhibit broad emission band owing to the 5d-4f transition of Ce3+. Because 5d orbital electrons are not shielded by outer 6s and 6p orbital electrons, the excitation and emission band position of Ce3+-activated phosphors is strongly affected by the crystal structure of host materials.1) According to the crystal field theory, the energy splitting of 5d excited level generally increases when Ce3+ occupied in the compact site with short bonding length in host lattice.2) The larger energy splitting will contribute to shift the excitation and emission band of Ce3+-activated phosphors to longer wavelength side. From the viewpoint of the crystal field theory, we have been selected the oxide materials including 5, 6 or 7 coordination site with short bonding distance in the lattice of host materials to develop novel white LEDs phosphor that show excitation and emission spectra at longer wavelength region. As a result, we could successfully synthesize the novel red emission phosphors,3,4) and in this study, we presents the luminescence properties of the novel oxide phosphors developed. In this study, we present our design concept for development of novel white LEDs phosphors and luminescence properties of Ce3+-activated phosphors designed by our original materials design concept.
This work was supported by a project from NEDO, New Energy and Industrial Technology Development Organization (Rare Metal Substitute Materials Development Project Development of Technology for Reducing Tb and Eu Usage in Phosphors for Fluorescent Lamp by High-speed Material Synthesis and Evaluation).
References

W. M. Yen, S. Shionoya, and H. Yamamoto, Phosphor Handbook 2nd ed., CRC Press, Boca Raton, FL (2007)

B. Henderson and G. G. Imbush, Optical Spectroscopy of Inorganic Solids, Clarendon, Oxford (1989).

Y. Kawano, S. W. Kim, T. Ishigaki, K. Uematsu, K. Toda, H. Takaba, and M. Sato, Opt. Mater. Express, 4, 1770 (2014).

T. Hasegawa, S. W. Kim, T. Ishigaki, K. Uematsu, T. Takaba, K. Toda, and M. Sato, Chem. Lett., 40, 828 (2014).
Luminescent Properties of Al2O3:Tb3+ Powders Embedded in Polyethylene Terephthalate Films
Authors: Mariscal B. L. , Carmona-Tellez Salvador , Falcony Ciro , Murrieta Sánchez Héctor 
Published: February 2020

The luminescent properties of Al2O3:Tb3+ powders embedded in polyethylene therephtalate (PET) films have been studied. Luminescent Al2O3:Tb3+ polycrystalline powders were synthesized by a simple evaporation method. X-ray diffraction (XRD) spectrum of powders of Al2O3:Tb3+ have the α-Al2O3 crystalline phase with peaks located at 2Θ = 25.78, 35.34, 37.96, 43.56, 45.8, 52.74, 57.7, 61.5, 66.74, 68.44, 77.12 and 80.94, which are associated with the planes (012), (104), (110), (113), (202), (024), (116), (018), (214), (300), (119) and (220), and the δ-Al2O3 phase is also present as identified by peaks in 2Θ = 32.82, 45.8, 61.36 and 66.74, associated with the planes (220), (400), (511) and (440). The powder embedded films were obtained by the spray pyrolysis technique. The photoluminescence and cathodoluminescence emission spectra from these samples show, in both cases, luminescence peaks associated with transitions within the electronic energy levels of Tb3+ ions. The dominant peak is at 544nm corresponding to the 5D4→7F5 transition and present 5D4→7F6,
5D4→7F4 y 5D4→7F3 transitions in 494, 587 y 622nm, when excited with λexc = 299 nm at room temperature. The CIE coordinates for non-doped PET films are (x = 0.2045, y = 0.3636), when excited with 270nm, this emission falls in the blue region. CIE diagram for powder embedded PET films excited with 299 nm have coordinates (x = 0.31, y = 0.5111); in this case, the emission is a combination of Al2O3:Tb3+ green light and PET blue light emissions. UV-Vis % transmission measurements on these films show that they are transparent (~ 80 and 95 %T).
A Versatile Bioanode with Improved Current Density and the Coulombic Efficiency through a Cascade Reaction
Authors: Zafar Muhammad Nadeem , Aslam Iqra , Murtaza Shahzad , Ludwig Roland , Gorton Lo 
Published: February 2020

To improve communications between enzymes and electrodes, many different methods were developed including the use of diffusional electron mediators, the “wiring” of enzymes through immobilization in redox polymers, the functionalization of enzymes with electron relays, and the use of nanomaterials. Recently a new promising strategy was reported, in which the glycoprotein glucose oxidase (GOx) was directly electrically contacted with the electrodes after removal of the glycosylating layer. Although a lot of advances in the electrical communication between enzymes and electrodes has made it possible to fabricate new biosensors and biofuel cells, the technologies still face challenging issues, such as development of long-term stable miniaturized implantable amperometric biosensors and biofuel cells.
Our approach to the development of a glucose biofuel cell anode is based on the combination of different redox enzymes with complementary oxidation positions thus forming a reaction cascade to oxidize the substrate at more than one position. Improvements in current density and coulombic efficiency of a glucose oxidizing electrode were realized by a combination of pyranose dehydrogenase from Agaricus meleagris (AmPDH) with either glucose dehydrogenase from Glomerella cingulata (GcGDH) or cellobiose dehydrogenase from Myriococcum thermophilum (MtCDH). The mixed enzyme electrode oxidizes glucose in several combinations at the C-1, C-2 and C-3 positions of the pyranose ring. This concerted action of enzymes increases (i) the coulombic efficiency by extracting more than 2 e- per substrate molecule and (ii) the current density of the electrode when the mass-transfer of substrates becomes rate limiting. The electrodes were investigated with flow injection analysis (FIA) using different substrates under physiological conditions (pH 7.4). These investigations showed that the product of one enzyme can be used as substrate for the other enzyme and maximally 6 e- can be gained from the oxidation of one glucose molecule using mixed enzyme electrodes like AmPDHb/GcGDH/Os-polymer 2 or the AmPDHa/MtCDH/Os-polymer 1. We propose a bioanode for use in biofuel cells with an increased current density and coulombic efficiency obtained by a cascade reaction catalyzed by redox enzymes with a different site-specificity for glucose.
Key words: Bio-anode, glucose dehydrogenase, Os-polymers, pyranose dehydrogenase, cellobiose dehydrogenase, coulombic efficiency
Exploiting the Reaction of Cytochrome C with Fructose Dehydrogenase for a Multilayer Electrode Construction
Authors: Lisdat Fred , Wettstein Christoph , Kano Kenji , Wollenberger Ulla 
Published: February 2020

The creation of analytical electron transfer (ET) chains based on the defined arrangement of enzymes and the redox protein cytochrome c (cyt c) on electrode surfaces represents an emerging field in bioelectronics.1,2 In this study we investigate the ET reaction of the flavin-dependent enzyme fructose dehydrogenase (FDH) with the redox protein cyt c. Two different pH optima are identified for the reaction with both proteins in solution, at acidic and neutral pH. When one reaction partner - cyt c - is immobilized on a modified gold electrode surface, ET proceeds efficiently at neutral pH which can be concluded from well shaped catalytic currents obtained in cyclic voltammograms. In addition a defined dependence on the substrate concentration is observed. In acidic media the reaction can also be verified but appears to be less efficient. This indicates that two different ET pathways between the enzyme and immobilized cyt c occur. Moreover, it is demonstrated that both partners can be assembled in a stable multilayer architecture, using the biopolymer DNA as connecting polyelectrolyte. The defined layered deposition of DNA with co-immobilized FDH and cyt c is verified by surface plasmon resonance (SPR) measurements. Prepared on electrodes, substantial catalytic currents are recorded upon addition of fructose. The response is found to be dependent on the number of layers deposited on the surface. This shows that an artificial signal chain can be constructed through multiple protein layers.
Our results contribute to the better understanding of the ET-reaction between FDH and cyt c in a surface confined state, providing the basic knowledge which may be relevant for the creation of innovative fructose sensitive electrodes.
1. Lisdat, F.; Dronov, R.; Moehwald, H.; Scheller, F. W.; Kurth, D. G., Chemical Communications 2009, 274-283.
2. Feifel, S. C.; Kapp, A.; Lisdat, F., in Biosensors Based on Aptamers and Enzymes, Springer 2014, 140, 253-298.
Single-Point Impedance Diagnostic for Internal Temperature Monitoring of Commercial Lithium-Ion Batteries
Authors: Spinner Neil S , Love Corey T , Tuttle Steven G , Rose-Pehrsson Susan L 
Published: February 2020

Temperature monitoring of commercial lithium-ion batteries is critical for maintaining safety. Extreme temperatures can result in harmful reactions, such as SEI and/or electrode decomposition, potentially leading to catastrophic thermal runaway and total battery failure [1-3]. Measuring battery temperature is typically done on the cell surface; however, this can be inaccurate, particularly during rapid heating events where differences between surface and internal temperatures can be as high as 40-50°C [4,5]. Therefore, developing methods for accurately and rapidly determining the internal temperature of lithium-ion batteries is crucial for safe operation and possible mitigation of failure events.
One technique that has been used to instantaneously monitor the state of health and internal temperature of lithium-ion batteries is Electrochemical Impedance Spectroscopy (EIS) [6-8]. Although this method is extremely effective, one key limitation is that the maximum detectable temperature has only been shown to be around 60-65°C. Considering that decomposition reactions typically begin around 100°C or higher, it is clear the temperature window for EIS internal temperature diagnostics will need to be expanded.
In this work, a single-point EIS diagnostic was developed using a correlation between the imaginary impedance and internal temperature of a commercial 18650 lithium-ion battery, as shown in Figure 1. This correlation was tested via several temperature vs. time programs, and Figure 2 shows results demonstrating close agreement of fit and actual temperatures up to around 95°C.
Figure Captions:

Figure 1. EIS correlation with internal temperature, along with fit, for commercial 18650 lithium-ion battery.

Figure 2. Fit vs. actual temperatures using single-point EIS diagnostic for temperature vs. time experiment on commercial 18650 lithium-ion battery.
References:

N. S. Spinner, C. R. Field, M. H. Hammond, B. A. Williams, K. M. Myers, A. L. Lubrano, S. L. Rose-Pehrsson and S. G. Tuttle, J. Power Sources, 279, 713 (2015).

T. B. Bandhauer, S. Garimella and T. F. Fuller, J. Electrochem. Soc., 158, R1 (2011).

F. Larsson and B.-E. Mellander, J. Electrochem. Soc., 161, A1611 (2014).

D. Belov and M.-H. Yang, Solid State Ionics, 179, 1816 (2008).

R. A. Leising, M. J. Palazzo, E. S. Takeuchi and K. J. Takeuchi, J. Electrochem. Soc., 148, A838 (2001).

C. T. Love, M. B. V. Virji, R. E. Rocheleau and K. E. Swider-Lyons, J. Power Sources, 266, 512 (2014).

R. Srinivasan, B. G. Carkhuff, M. H. Butler and A. C. Baisden, Electrochim. Acta, 56, 6198 (2011).

N. S. Spinner, C. T. Love, S. L. Rose-Pehrsson and S. G. Tuttle, Electrochim. Acta, Submitted.

Figure 1
Quantifying the Impact of Overdischarge on Large Format Lithium Ion Cell Safety
Authors: Fuentevilla Daphne , Mansour Azzam , Hendricks Christopher 
Published: February 2020

Lithium-ion battery safety has always been a concern; however, safety is becoming increasingly important due to the proliferation of high capacity, high power cells and modules utilized in electric vehicle, grid, aerospace, and military applications. While safety measures such as battery management algorithms, thermal management, fuses, and sensors can reduce the risk of catastrophic failure, not all of the risk can be managed while the battery is active. Self-discharge of lithium ion cells below a zero state of charge voltage, overdischarge, is one such case. Overdischarge has generally been considered more of a performance issue than a safety concern unless coupled with recharge. However, with battery-powered devices potentially left for long periods of time in storage, DoD interest in extending the shelf life of devices in the field, and proliferation of battery packs composed of large numbers of cells, there is an increased interest in determining limits of low voltage recharge and developing a methodology for determining safety limits. Furthermore, overdischarge is a class of safety risk that is inherent to the cell and cannot be prevented with passive protection devices. This talk will cover safety concerns associated with overdischarge of large format lithium-ion batteries including gas generation, copper dissolution at low voltage and precipitation upon recharge, and health of the Solid Electrolyte Interphase layer.
While the gas generation behavior of lithium-ion cells has been studied extensively[1], a methodology for assessing the gas generation prior to full thermal runaway has not been developed. It has been demonstrated that oxygen can be released from the electrode structure due to a destabilization of the crystal lattice.[2] Additionally, electrolyte decomposition, typically during charging, contributes to gas buildup within the cell that can eventually cause rupturing of the casing.[3] We discuss methods for assessing the amount of gas generated at intermediate stages of cell abuse. Finally, we present recent data on the safety implications of copper dissolution in overdischarged large format cells.

[1] E. Roth, C. Crafts, D. Doughty, and J. McBreen, “Advanced technology development program for lithium-ion batteries: thermal abuse performance of 18650 li-ion cells,” Sandia National Laboratory Report, SAND2004-0584, 2004
[2] W. Kong, H. Li, X. Huang, and L. Chen, “Gas evolution behaviors for several cathode materials in lithium-ion batteries,” Journal of Power Sources Vol. 142, 2005, pp. 285-291.
[3] K. Kumai, H. Miyashiro, Y. Kobayashi, K. Takei, and R. Ishikawa, “Gas generation mechanism due to electrolyte decomposition in commercial lithium-ion cell,” Journal of Power Sources Vol. 81-82, 1999, pp. 715-719.
(Invited) Tailoring Polymer Structure and Composition for High-Power and High-Charge Capacity Redox Electrodes
Authors: Roberts Mark E. 
Published: February 2020

Conventional batteries are efficient at delivering a continuous supply of power; however, limited discharge rates prevent their use in high power applications. Many energy systems require sources that can repetitively supply high power bursts, which include electric transportation, utilization of renewable energy sources, and portable electronics. This demand can be addressed using advanced Li-ion batteries and supercapacitors, devices that combine the high power, rapid switching, and exceptional cycle life of a capacitor with the high energy density of a battery. Electroactive conducting polymers are suitable candidates for high-power energy storage, but they are currently limited by i) the lack of nano/micro-structure control over large areas, ii) relatively low charge-capacity, and iii) material stability.
In this presentation, we will discuss our group’s recent progress on engineering high-energy and high-power electrode materials for energy storage, including scalable synthesis of nano/micro-structured polymer electrodes and integrating high-charge capacity redox polymers. To increase power, redox polymer microtubes with nanometer thickness are synthesized on large area substrates by controlling gas nucleation density, which guides to formation of nanostructured electrodes. Nanostructured electrodes exhibit superior performance at high charge/discharge rates relative to planar electrodes. To increase electrode charge capacity, redox molecules and polymer are incorporated into conducting polymer electrodes during electrochemical synthesis. The capacitance of polypyrrole electrodes can be increased from 249 F/g to 550 F/g using hydroquinone dopants, and up to 400 F/g using naturally abundant Alkali lignin. We show that the conditions for electrode synthesis, along with the type (and molecular composition) of lignin, exhibit strong correlations with electrode performance.