bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determining Membrane Degradation in Polymer Electrolyte Fuel Cells by Effluent Water Analysis
Authors: Bodner Merit , Rami Mija , Marius Bernhard , Schenk Alexander , Hacker Viktor 
Published: February 2020

The degradation of the polymer electrolyte is one of the dominant factors, which limits the lifetime of the polymer electrolyte fuel cells (PEFCs). Therefore, the understanding and mitigation of all contributing degradation phenomena is fundamental in order to establish the PEFC as competitive product.
Membrane degradation is often quantified by analysing the fluoride emission rate by determining the fluoride content in the effluent water. However, when oligomers (i.e. larger polymer fragments) are released, the ion conductivity of the ionomer declines without extensive fluoride release, as the carbon backbone fluorine bonds are still intact. Thus, it is necessary to conduct effluent water treatment in order to determine the total fluorine emission rate (tFER) instead of the fluoride emission rate (FER) only [1].
In the presented work, an accelerated stress test (AST) was conducted in a single cell with a segmented S++ current scan shunt device with a sensor plate on the cathode for spatial current and temperature measurements in 10x10 and 5x5 segments, respectively. A membrane electrode assembly was characterised in situ [2]. Throughout 100 hours of stress testing, the effluent water was collected and used to determine the FER, using a fluoride selective electrode (Figure 1) [3]. Furthermore, effluent water samples were treated with KOH following different protocols. The alkaline treatment decomposes residual ionomer fragments for the detection of the total fluorine emission rate. The tFER allows more profound assumptions regarding the extent of the membrane degradation and further, gives insight into the underlying degradation mechanism.
In preliminary results it is shown that by conducting alkaline effluent water treatment at a temperature of 500 °C the amount of detected fluoride was increased significantly (Figure 2). Thus it can be concluded that not all emitted fluorine is detectable without previous treatment, indicating that the electrolyte membrane decomposes into oligomeric fragments.
Acknowledgement
The research leading to these results has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement n° 621216.
[1] Aarhaug TA, Svensson AM. Degradation Rates of PEM Fuel Cells Running at Open Circuit Voltage. ECS Trans., vol. 3, ECS; 2006, p. 775–80. doi:10.1149/1.2356197.
[2] Bodner M, Cermenek B, Rami M, Hacker V. The Effect of Platinum Electrocatalyst on Membrane Degradation in Polymer Electrolyte Fuel Cells. Membranes (Basel) 2015;5:888–902. doi:10.3390/membranes5040888.
[3] Bodner M, Hochenauer C, Hacker V. Effect of pinhole location on degradation in polymer electrolyte fuel cells. J Power Sources 2015;295:336–48. doi:10.1016/j.jpowsour.2015.07.021.

Figure 1
Detection of Superoxide Anion Radical in Anion Exchange Membrane Fuel Cells Using in-Situ Fluorescence Spectroscopy
Authors: Zhang Yunzhu , Ramani Vijay K 
Published: February 2020

Anion exchange membrane (AEM) stability is a long-standing challenge that has limited the widespread development and adoption of AEM fuel cells. It is essential to understand the mechanism of AEM degradation during fuel cell operation. There are multiple modes of AEM degradation, broadly classified as chemical, mechanical and thermal degradation. Chemical degradation is among the most destructive modes, and can be further sub-divided into nucleophilic degradation (induced by the hydroxide ion), and oxidative degradation (induced by reactive oxygen species). While the former has been extensively studied, there is minimal work on oxidative AEM degradation.
The reactive oxygen chemical species produced during the operation of an AEM fuel cell have hitherto not been detected during operation. Given the high pH, it is postulated that superoxide anion radicals (O2
·-), as opposed to hydroxyl radicals, are primarily involved in the degradation progress. The objective of this study was to confirm the O2
·- formation during AEM fuel cell operation and to monitor in real-time the rate of O2
·- generation in an operating fuel cell using in-situ fluorescence spectroscopy.
1,3-diphenlisobenzofuran (DPBF) was chosen as the fluorescence probe, the sensitivity of which towards O2
·- was evaluated by performing ex-situ experiments in a semi-batch reactor. We demonstrate that the fluorescence intensity of this dye selectively decreased upon exposure O2
·-. DPBF was then incorporated into an AEM (membrane was solution cast after mixing the dye with the casting solution), which was assembled into a fuel cell. O2
·-
generation in an operating AEM fuel cell was then monitored via in-situ fluorescence spectroscopy using a bifurcated optical probe, when the cell was operated in H2/O2 mode. To confirm the impact of O2
·-
on AEM degradation, independent experiments (without dye) were performed under identical conditions, under both H2/O2 and N2/N2 modes, and the ionic conductivity and ion exchange capacity were monitored to estimate degradation extent. From our in-situ fluorescence studies, we were able to estimate the rate constants and activation energy for oxidative AEM degradation in an operating AEM fuel cell.
CO2/H2o High Temperature Co-Electrolysis Using LaFeO3-Based Oxide Cathode
Authors: Wu Kuan-Ting , Ishihara Tatsumi 
Published: February 2020

An increasing awareness of severe environmental impact has been seriously concerned due to the increasing demand for energy, the diminishing resources of fossil fuels, and the tremendous effects on climate change. An important indication is from global warming effect, caused by effluent greenhouse gas emission (mainly CO2). Therefore, efficient management and utilisation of CO2 and energy (generation and storage) are required attention urgently. Co-electrolysis of steam and CO2in a solid state electrolysis cells (SOECs) is a promising strategy, which may provide an approach to not only effectively reduce climate impact, but also produce useful fuels (such as syngas and hydrocarbon source) through waste heat. Thus, this allows the conversion of electricity into a fuel, while giving new opportunities for efficient and effective use of energy.
Ni-based cermet materials are usually used as fuel electrodes for SOECs, while constant circulation of reducing gas (H2 or CO) is required in order to prevent the oxidation of the metallic phase, which can lead to an issue of long-term operation. In addition, the stability of the conventional cathodes applied in electrolyser is still required to be much improved. Hence, decrease in degradation rate is essential for the application of high-temperature electrolyser. Therefore, utilisation of oxides as fuel electrodes has been highly suggested instead of metallic based electrodes. Previous our study has reported a promising LaFeO3-based perovskite material as a fuel electrode for CO2 electrolysis, showing a good activity and cell performance for CO2 reduction without carbon formation.[
1
]

In this study, we further investigate co-electrolysis of CO2 and steam, using LSGM and LaFeO3-based materials for the electrolyte and cathode, respectively. Galvanostatic measurements and electrochemical impedance spectroscopy has been conducted to investigate the cell performance. A comparable current density of over ~0.61 A/cm2 has been achieved at ~1.6 V and 800°C. This study was focused on the formation of the syngas CO/H2 in operation. The content of the product gases was measured by gas chromatography installed with a thermal conductive detector. As Ni-based cermet is used as a cathode, a H2-enriched gas composition was formed particularly at < 800°C because of the dominant electrolysis of H2O and water-gas shift reaction (CO+H2O↔CO2+H2). However, in case of LaFeO3-based perovskite oxide cathode, a reasonable electrolysis current was achieved and the CO/H2 ratio in product was similar to the CO2/H2O in feeding composition. This suggests that LaFeO3-based oxide is active to CO2 electrolysis and presents low activity for water-gas shift reaction. Therefore, using LaFeO3-based oxide as a cathode of a co-electrolyser may be feasible for the control of CO/H2 ratio.
[1] T. Ishihara, K.-T. Wu, S. Wang, ECS Trans. 2015, 66, 197.
Proton Conduction Properties of Bzcy and Szcy Perovskites Type Oxides; Addressing the Effect of Dopant Levels and Proton Content
Authors: Leonard Kwati , Lee Young-Sung , Okuyama Yuji , Miyazaki Kuninori , Matsumoto Hiroshige 
Published: February 2020

Electrochemical devices based on perovskites-type proton conducting oxides, are gaining wide interest as promising green technologies for hydrogen production and seperation. Interest in this class of materials stems from their lower activation energy for proton transport (typically 0.3-0.6 eV) relative to that for oxide ion conduction, thus making them suitable electrolyes for steam electrolysis cell operation at intermediate temperature. Despite the advances in proton-conducting electrolytes, their development still lag behind the oxygen-ion counterparts. The most prominent limitation being, conductivity, chemical stability, incomplete hydration of the electrolytes, as well as the grain boundary resistance.
In the present contribution, starting from SrZr0.5Ce0.4Y0.1O3-δ, we examined the effects of Ba substitution for Sr and the doping level of Y on the lattice structure, electrical properties, proton content as well as chemical stability of the following compositions A(Zr5/9Ce4/9)1-x
Y
x
O3-
δ
, (A= Ba, Sr and x=0.1, 0.2). Thermo-gravimetric analyses revealed almost similar proton concentration in both SZCY541 and SZCY(54)8/9-2 with a constant Zr/Ce fraction of 5:4. Both samples showed almost comparable proton conductivities in humidified 1% H2 hydrogen. BZCY(54)8/9-2 shows a maximum proton limit of 13.3 mol % compared to only 6.03 mol % for SZCY(54)8/9-2 and retained the highest proton conductivity of 1.44 × 10-2 Scm-1 in wet 1 % H2 at 600 oC (Fig. 1.) as well as excellent chemical stability under 80 % steam for 200 hours. Ba at A-site provides higher proton mobility than Sr. It is also evident from the data that the bulk and grain boundary contributions on the conductivity were strongly dependent on the A-site host, with the grain boundary response dominating the impedance spectra of the BZCY system relative to the SZCY. However the major difference in conductivity among the compositions originates mostly from the differences in proton concentration levels as well as the magnitude of the grain boundary contribution. This paper discusses these aspects based on experimental results as well as steam electrolysis using SZCY541 and BZCY(54)8/9-2 as electrolytes.

Acknowledgement

This work was supported by the Council for Science, Technology and Innovation　(CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “energy carrier”(Funding agency: JST)　and by World Premium International Research Center Initiative (WPI), MEXT Japan.

Figure 1
(High Temperature Materials Division Outstanding Achievement Award) A Country Boy Finds Materials Science
Authors: Anderson Harlan U. 
Published: February 2020

I am greatly honored to have been chosen by the High Temperature Materials Division of the Electrochemical Society to receive their Outstanding Achievement Award for 2016.
For this lecture, I will give a brief review of who I am, my career in teaching, my research interests in both insulating and electrical conducting oxides and focus on what I perceive as my major contributions to the world of ceramics (high temperature materials).
Ceramics are well-known for their ability to serve as electrical and thermal insulators, structural components and for corrosion protection. In addition, their unique ability to interact with electric and magnetic fields yields properties that can vary many orders of magnitude. These include the dielectric permittivity, electrical conductivity, piezoelectricity, magnetic susceptibility, and magneto-and electro-optics. With these variety of properties, the use of ceramic components is so vast that it includes most of the devices, which we encounter and use every day.
For example, the electrical insulating properties allow use of materials such as alumina for substrate in integrated circuits as well as high voltage insulators (e.g. computers. spark plugs, TV). Electrical energy storage capabilities have allowed ceramic materials to be integral parts of electronic circuits. Both require active component isolation as well as local power supplies which capacitors provide (e.g. TV, computers, cell phones). High electronic conductivity allows ceramics to be used as electrodes as well as resistors for a wide range of applications. Piezoelectric properties allow ceramics to serve as transducers for many everyday applications (e.g. ultrasonic imaging and smoke detectors]. The ability of zirconia to display high oxygen conductivity has enabled a rapidly growing list of applications such as oxygen sensors (every automobile has one), oxygen separations membranes and electrolytes for solid oxide fuel cells.
All of these applications of ceramics are perfect examples where understanding the structure-property relationships at multiple scale levels were a key necessity for success. Amongst the crystallographic symmetries which have yielded the most varied properties, the perovskite system reigns supreme. I have dedicated my research career to this system and explore the influence of composition and defect structure on both electrical insulating and conducting systems. I first will discuss the properties and characteristics of this unique class of ceramics which allows them to be utilized both as electrical insulators as well as electrical conductors. I will then give some examples in which the properties are tailored to meet requirements of specific applications: capacitors, solid oxide fuel cells, and sensors.
Stability and Performance Investigation of Co-Sputtered Ni Cermet Thin Films at Reduced Temperature
Authors: Lee Yeageun , Yu Wonjong , Lee Yoon Ho , Kim Yusung , Cha Suk Won 
Published: February 2020

Thin film solid oxide fuel cells (thin film SOFCs) were introduced to reduce the high operating temperature of traditional SOFCs. By employing thin film techniques such as sputtering, atomic layer deposition, and pulsed laser deposition, less than 1 μm-thick electrolytes have been successfully fabricated and functioned properly. Through these thin film electrolytes, the low ionic conductivity of the electrolyte materials at reduced temperature is compensated by the shortened travel length of the oxygen ions. However, low temperature also leads the poor electrode activity, and this lowered activity has not been fully overcome.
In this study, we investigated various types of Ni-based cermet films to gain better electrode activity. The cermet films were fabricated by magnetron sputtering. For ion-conducting materials, yttria-stabilized zirconia (YSZ) and scandia-stabilized zirconia (ScSZ) were used. These ion-conducting materials were co-sputtered with Ni. The sputtering power of each material was varied for changing Ni contents of the films. To obtain the Ni contents, we utilized X-ray photoelectron spectroscopy (XPS). Four-point probe measurement was also conducted to verify the degree of Ni percolation of the films. In addition, the surface and cross-sectional images of the films were observed to investigate the microstructure and porosity.
For analyzing the electrochemical performance of the co-sputtered cermet films at reduced temperature, we fabricated several experimental SOFCs. On the one side of the solid electrolyte pellet, the thin cermet anode was deposited, while thin Pt cathode was deposited on the other side of the pellet. Then, the experimental SOFCs were operated at below 500 oC. During the operation, the j-V characteristics and electrochemical impedance spectroscopy (EIS) of the cells were studied. The thermal stability of the cells was also characterized by potentiostatic measurement and the measured data were compared to the cell with pure Ni anode.
Electrochemical Characteristics of Nickel and Ceria Infiltrated Nano-Structured La0.2Sr0.8TiO3 Anodes for Solid Oxide Fuel Cells By Infiltration
Authors: Lee Min-Jin , Choi Byung Hyun , Ji Mi Jung , Hwang Hae Jin 
Published: February 2020

A La-doped SrTiO3 (LST) is an alternative anode material of solid oxide fuel cells (SOFC). The LST has a high electronic conductivity and chemically stable under a reduced atmosphere. In addition, it has excellent carbon deposition resistance and high tolerance of sulfur in hydrocarbon fuels. However, the LST suffers from a low catalytic activity toward the oxygen reduction reaction. Thus, it needs to improve the catalyst activity of the LST anode.
In this study, nickel and gadolia-doped ceria (GDC) infiltrated nano-structured LST anodes were proposed in order to improve the catalytic activity of the LST-based oxide anode. Nano-sized Ni and GDC were homogeneously dispersed in a LST backbone by infiltration. Ni/GDC infiltrated LST showed higher catalytic activity than Ni and GDC infiltrated ones, which means that the synergistic effect can be expected in the Ni/GDC infiltrated LST. It seems that the polarization resistance (Rp) depended on the infiltrated Ni and GDC content and their dispersion state or microstructure. We analyzed the correlation between the microstructure of the infiltrated anode and electrochemical characteristics.
Understanding the Effect of Temperature on the Sulfur Tolerance of a Ca Rich Ferrite SOFC Electrode
Authors: Addo Paul , Ahsen Ali , Buyukaksoy Aligul , Molero-Sánchez Beatriz , Ozturk Osman , Birss Viola 
Published: February 2020

Previously, we have shown that a symmetrical La0.3Ca0.7Fe0.7Cr0.3O3-δ (LCFCr) SOFC full cell (LCFCr used at both electrodes) exhibits very good electrochemical performance in H2 and CO at the fuel cell and also has good sulfur tolerance in wet H2 with a low ppm H2S content at 800 oC [1]. In fact, a somewhat enhanced performance of the LCFCr anode towards the hydrogen oxidation reaction was observed under these conditions [1]. However, the effect of temperature, which is known to have a significant impact on the sulfur tolerance of conventional Ni-based anodes [2-6], has not yet been studied. Therefore, in this work, both a symmetrical full cell and a three electrode half cell configuration, using LCFCr for all of the electrodes, were constructed and tested to better understand the sulfur tolerance of this Ca rich ferrite based perovskite in humidified H2 at temperatures ranging from 600-800 oC.
Our preliminary potentiostatic data have shown that, in both the full and half-cell mode in low ppm H2S, the LCFCr electrode exhibits an enhancement in the hydrogen oxidation reaction (HOR) kinetics at 750-800 oC, while between 600 and 700 oC, the LCFCr electrode shows some form of deactivation. For instance, in the three electrode half-cell study at a constant anodic overpotential of 100 mV, the current density of the LCFCr electrode increased by 7-10% with the addition of 9 ppm H2S to 50% humidified H2 in the higher temperature range, while at 600 oC and 650 oC, the current density decreased by 2% and 15%, respectively. This deactivation was found to be fully reversible when H2S was removed from the gas stream, however, indicating that there was no permanent damage to either the electrodes, the interfaces, or the current collectors. Similarly, open circuit impedance data for the symmetrical full cell study showed that the polarization resistance (Rp) decreased from 1.0 to 0.95 Ωcm2 with the addition of 9 ppm H2S to 30% humidified H2 at 800 oC, while at 650 oC, Rp increased from 15.3 to 17.6 Ωcm2. To better understand these results, we are employing various surface characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), to better understand the interaction between H2S and LCFCr, as well as the type of S species formed, over the full temperature range in low ppm H2S.

References

[1] P. K. Addo, B. Molero-Sánchez, A. Buyukaksoy, S. Paulson and V. Birss, ECS Trans., 66 (2), 219 (2015).
[2] L. Debeeleeck et al, Phys.Chem.Chem.Phys., 16, 9383(2014).
[3] J.-H. Wang, M. Liu, Electrochem. Commun., 9, 2212 (2007).
[4] D.G. Ivey et al, J. Power Sources, 195, 6301 (2010).
[5] C. Bartholomew, Appl. Catal. A: Gen., 212, 17 (2001).
Fabrication of Solid State Ionic Devices Using Additive Manufacturing
Authors: Benavidez Angelica D , Tsui Lok-kun , Cook Adam , Diantonio Christopher , Chavez Tom , Garzon Fernando H 
Published: February 2020

The fabrication of solid state ionic devices requires customization of size, shape, geometry, and composition for various components. Traditionally used fabrication methods are tape casting and screen printing. Although these methods are well developed they are difficult, time consuming, and costly to adjust to fit particular device requirements. Sandia National Laboratory has recently developed Robocasting, an additive manufacturing technique that was developed as a method that allows for the adaptation needed to rapidly prototype specialty ceramics in a more economically efficient way.
Robocasting is currently used commercially to produce complex ceramic parts that are used in various applications including catalyst supports and casting filters. The technology has not been developed for the fabrication of ceramic electrochemical devices. While this has worked well for these limited specific needs, this technology has been optimized primarily for alumina based ceramic materials. In order to expand the versatility of this method for solid state ionic devices, powder precursors of solid electrolytes and electrode materials with specific properties must be developed. Tailoring the rheology of the pastes and slurries used in this extrusion method is an important aspect that determines the resolution of the resulting ceramic components. Another challenge is controlling the residual stress and shrinkage through the material properties of various components.
We have applied this additive manufacturing technique to our unique design of gas sensors. These multi-component sensors consist of a yttria-stabilized zirconia substrate onto which a set of three solid electrodes and a porous YSZ electrolyte are deposited. The production method employed involves the direct printing of a suspended powder of the electrode and electrolyte components using Robocasting technology. This allows for the rapid prototyping of these devices. The key to this process is the use of high temperature co-fired ceramics which enables all components to be fired together. The electrodes consist of a platinum counter electrode and lanthanum-strontium-chromite and gold-palladium working electrodes. By taking advantage of the dissimilar electrochemical catalytic activity of these materials, the difference in mixed potential between two electrodes can be used to quantify the concentration and discriminate the type of gas present. These devices are capable of detecting NOx, hydrocarbons, H2, and NH3 at concentrations on the order of parts per million.

Figure 1