High-temperature Cell Research Articles

Generation of miniploid cells and improved natural transformation procedure for a model cyanobacterium Synechococcus elongatus PCC 7942.

The biotechnologically important and naturally transformable cyanobacterium, Synechococcus elongatus PCC 7942, possesses multiple genome copies irrespective of its growth rate or condition. Hence, segregating mutations across all genome copies typically takes several weeks. In this study, Synechococcus 7942 cultivation on a solid growth medium was optimised using different concentrations of agar, the addition of antioxidants, and overexpression of the catalase gene to facilitate the rapid acquisition of colonies and fully segregated lines. Synechococcus 7942 was grown at different temperatures and nutritional conditions. The miniploid cells were identified using flow cytometry and fluorimetry. The natural transformation was carried out using miniploid cells and validated with PCR and high performance liquid chromatography (HPLC). We identified that 0.35% agar concentration and 200 IU of catalase could improve the growth of Synechococcus 7942 on a solid growth medium. Furthermore, overexpression of a catalase gene enhanced the growth rate and supported diluted culture to grow on a solid medium. Our results reveal that high temperature and phosphate-depleted cells contain the lowest genome copies (2.4 ± 0.3 and 1.9 ± 0.2) and showed the potential to rapidly produce fully segregated mutants. In addition, higher antibiotic concentrations improve the selection of homozygous transformants while maintaining similar genome copies at a constant temperature. Based on our observation, we have an improved cultivation and natural transformation protocol for Synechococcus 7942 by optimising solid media culturing, generating low-ploidy cells that ultimately reduced the time required for the complete segregation of engineered lines.

Discovery of active off-axis hydrothermal vents at 9° 54′N East Pacific Rise

Comprehensive knowledge of the distribution of active hydrothermal vent fields along midocean ridges is essential to understanding global chemical and heat fluxes and endemic faunal distributions. However, current knowledge is biased by a historical preference for on-axis surveys. A scarcity of high-resolution bathymetric surveys in off-axis regions limits vent identification, which implies that the number of vents may be underestimated. Here, we present the discovery of an active, high-temperature, off-axis hydrothermal field on a fast-spreading ridge. The vent field is located 750 m east of the East Pacific Rise axis and ∼7 km north of on-axis vents at 9° 50'N, which are situated in a 50- to 100-m-wide trough. This site is currently the largest vent field known on the East Pacific Rise between 9 and 10° N. Its proximity to a normal fault suggests that hydrothermal fluid pathways are tectonically controlled. Geochemical evidence reveals deep fluid circulation to depths only 160 m above the axial magma lens. Relative to on-axis vents at 9° 50'N, these off-axis fluids attain higher temperatures and pressures. This tectonically controlled vent field may therefore exhibit greater stability in fluid composition, in contrast to more dynamic, dike-controlled, on-axis vents. The location of this site indicates that high-temperature convective circulation cells extend to greater distances off axis than previously realized. Thorough high-resolution mapping is necessary to understand the distribution, frequency, and physical controls on active off-axis vent fields so that their contribution to global heat and chemical fluxes and role in metacommunity dynamics can be determined.

(Digital Presentation) Photo-Thermo-Electrochemical Cells for on-Demand Solar Power and Hydrogen Generation

Converting solar energy into power and hydrogen provides a promising pathway to fulfilling instantaneous electricity demand (power generation) as well as continuous demand via storing energy in chemical bonds (hydrogen generation). Co-generation of power and hydrogen is of great interest due to its potential to overcome expensive electricity storage in conventional PV plus battery systems. Both solar thermochemistry processes and photo-electrochemical cells (PECs) are extensively explored technologies to produce solar hydrogen. The key challenges for solar thermochemistry processes are extremely high operating temperature (~ 1500 oC) and low demonstrated efficiency (< 1% for hydrogen generation). For PECs, the limited solar absorption together with sluggish electrochemical reactions, especially for OER, leads to limited theoretical solar fuel generation. Operating PECs at high temperature will lead to decreased photovoltage and interface stability. Inspired by the thermally regenerative batteries, we propose a photo-thermo-electrochemical (PTEC) device that uses the solid oxide-based moderate high temperature cell (~1000 ℃) as the photo-absorber for simultaneously converting concentrated solar radiation into heat and generating fuel or power electrochemically driven by the discharging power from the low temperature cell (~700 ℃). PTEC device enables full solar spectrum utilization, highly favorable thermodynamics and kinetics, and cost-effectiveness. A continuous PTEC device has two working modes, which are voltage differential (VD) mode and current differential (CD) mode. The current-voltage characteristics of a PTEC device are shown in Figure 1. It mainly consists of five parts. A high temperature cell (HTC) serves as a solar absorber and a low temperature cell (LTC) serves as heat recovery. Besides, the opposite electrochemical reactions take place in two cells meaning that HTC and LTC can also function as a hydrogen production as well as an electricity generator component, respectively. Heat exchanger(s) is placed between the HTC and LTC and hot fluids pass through a heat exchanger before entering LTC to reduce heat losses to environment as well as reducing input solar energy. The VD mode and CD mode can be realized in PTECs via controlling of DC-DC converter. In order to identify the main parameters, we develop a multi-physics model based on finite element method, including mass, heat and charge transfer, and electrochemical reactions. In addition, heat exchange is modeled by solving energy balance equation, DC-DC convertor is assumed by constant efficiency, and a lumped parameter model is used to describe solar receiver including energy losses of conduction and reradiation. This framework also allows us to provide design guidelines for PTEC devices with high solar-to-electricity (STE) efficiency and solar-to-hydrogen (STH) efficiency. The maximum STE and STH efficiency under reference conditions of PTEC device was found to be 4 % and 2 %. A further improved performance in terms of STE and STH efficiency are about 19 % and 16 %, respectively, via optimizing temperature configuration between HTC and LTC and material properties. It is also interesting to note that STH can reach higher than 80 % of STE at a large temperature difference, which shows a promising energy storage device by storing excessive electrical power in form of hydrogen. The main results show that the temperature of HTC and efficiency of heat exchange are key parameters to optimize PTEC efficiency. The performance of DC-DC convertor dominates STH efficiency. Besides, ionic conductivity of electrolyte can contribute to significantly expanding the operating current density range. The PTEC is a promising technology for solar energy conversion and storage as it is able to produce electricity and hydrogen in a single device. The solar conversion efficiency predicted with our numerical model supports that by optimizing the design and operational conditions, this technology can compete with existing solar fuel pathways. Figure 1

Single-Layer-Graphene and Electrochemical Exfoliated Graphene Oxide for HT-PEMFC

High-temperature proton exchange membrane fuel cell (HT-PEMFC) is promising with its low demand for hydrogen purity, simple water management, and high waste heat utilization [1][2]. Although polybenzimidazole (PBI), as a typical high-temperature fuel cell membrane, has been developed for a long period, it still has defects such as phosphoric acid leaching and insufficient mechanical properties under high acid doping level [3][4]. With its unique 2D hexagonal grid structure and its electron cloud arrangement, single-layer graphene (SLG) can block the passage of any atoms [5]. However, hydrogen protons can easily penetrate SLG through a unique intermediate state mechanism to make it have excellent proton conductivity [6]. SLG's high proton conductivity combined with its excellent mechanical properties and thermal conductivity make it an ideal material for blocking phosphoric acid leaching. The SLG prepared by the chemical vapor deposition (CVD) method was transferred to the surface of catalyst layer of electrodes by the wet chemical transfer method. Due to the rupture and incompleteness of the SLG during the transfer process, the coverage rate of the SLG on the electrode surface is about 55%. This incomplete coverage facilitates small quantities of phosphoric acid leaching from PBI membrane to electrodes, which increases the three-phase boundary area and improves the performance of the HT-PEMFC. After 70 hours of accelerated stress testing (AST), the peak power density of membrane-electrode-assembly (MEA) with SLG on both sides of the cathode and anode can reach 480 mW cm-2, while the peak power density of MEA based on pure PBI membrane is only 249 mW cm-2. The quantification of phosphoric acid in the electrode by Lab based X-ray micro-computed tomography and the Raman spectroscopic mapping of the MEA cross-section shows that SLG can mitigate the leaching of phosphoric acid in the PBI film and improve the durability of HT-PEMFC. Graphene oxide (GO) is a low-cost application of graphene. Its doping in the PBI membrane can also reduce the leaching of phosphoric acid through enhancing the interaction between phosphoric acid and the PBI membrane [7]. A reactor based on 3D printing was designed so that natural graphite flakes can be used for electrochemical exfoliation to achieve rapid, safe, environmentally friendly, and mass production of GO. The electrochemically exfoliated (E)GO is doped in the PBI membrane. The 0.5%, 1% and 2% EGO loadings in the PBI membrane increased the peak power density by 13.8%, 24.4% and 29.2%, respectively.[1] Y.-L. Ma, J.S. Wainright, M.H. Litt, R.F. Savinell, Conductivity of PBI Membranes for High-Temperature Polymer Electrolyte Fuel Cells, Journal of The Electrochemical Society. 151 (2004) A8. https://doi.org/10.1149/1.1630037/XML.[2] H. Su, S. Pasupathi, B. Bladergroen, V. Linkov, B.G. Pollet, Optimization of gas diffusion electrode for polybenzimidazole-based high temperature proton exchange membrane fuel cell: Evaluation of polymer binders in catalyst layer, International Journal of Hydrogen Energy. 38 (2013) 11370–11378. https://doi.org/10.1016/J.IJHYDENE.2013.06.107.[3] S. Galbiati, A. Baricci, A. Casalegno, R. Marchesi, Degradation in phosphoric acid doped polymer fuel cells : A 6000 h parametric investigation, International Journal of Hydrogen Energy. 38 (2013) 6469–6480. https://doi.org/10.1016/j.ijhydene.2013.03.012.[4] S.H. Eberhardt, F. Marone, M. Stampanoni, F.N. Büchi, T.J. Schmidt, Quantifying phosphoric acid in high-temperature polymer electrolyte fuel cell components by X-ray tomographic microscopy, Journal of Synchrotron Radiation. 21 (2014) 1319–1326. https://doi.org/10.1107/S1600577514016348.[5] S. Hu, M. Lozada-Hidalgo, F.C. Wang, A. Mishchenko, F. Schedin, R.R. Nair, E.W. Hill, D.W. Boukhvalov, M.I. Katsnelson, R.A.W. Dryfe, I. V. Grigorieva, H.A. Wu, A.K. Geim, Proton transport through one-atom-thick crystals, Nature. 516 (2014) 227–230. https://doi.org/10.1038/nature14015.[6] S.M. Holmes, P. Balakrishnan, V.S. Kalangi, X. Zhang, M. Lozada-Hidalgo, P.M. Ajayan, R.R. Nair, 2D Crystals Significantly Enhance the Performance of a Working Fuel Cell, Advanced Energy Materials. 7 (2017) 1–7. https://doi.org/10.1002/aenm.201601216.[7] J. Li, X. Zeng, T. Ren, E. van der Heide, The Preparation of Graphene Oxide and Its Derivatives and Their Application in Bio-Tribological Systems, Lubricants 2014, Vol. 2, Pages 137-161. 2 (2014) 137–161. https://doi.org/10.3390/LUBRICANTS2030137.

Lanthanum Strontium Manganite Oxygen Electrode Reaction Mechanism in High-Temperature Solid Oxide Water Electrolysis

High-temperature solid oxide water electrolysis cells have become the center of attention of the research community owing to several advantages over traditional water electrolysis technologies. Among others, solid oxide water electrolysis represents highly efficient technology with the possibility to operate in a reversible regime (fuel cell/steam electrolysis). Despite the fast reaction kinetics due to the high operating temperature (600-900 °C). A more detailed understanding of the reaction mechanism is of critical importance to further develop this technology.Lanthanum-strontium-manganite La1-xSrxMnO3-δ is still considered a viable material for an oxygen electrode due to its high electrical conductivity, good chemical stability, and thermomechanical compatibility with various solid electrolytes. However, its negligible ionic conductivity is frequently reported in the literature. Although, La1-xSrxMnO3-δ is utilized as an oxygen electrode for several decades and its properties are reported in the literature, the reaction mechanism occurring on this oxygen electrode is insufficiently described, with multiple discrepancies occurring between the individual authors. The open literature almost exclusively considers the oxygen reduction reaction. Here La1-xSrxMnO3-δ is described exclusively as a pure electron conductor. In the case of the oxygen evolution reaction, only the mechanism reversed to the oxygen reduction is considered, which is clearly an oversimplification.Recent articles tend to connect the defect chemistry of La1-xSrxMnO3-δ and electrochemistry to disapprove the generally accepted description of reaction mechanisms, owing to the rather low agreement between theory and experimental data. In the framework of this study, a series of experiments was conducted, both under current-less as well as current-load conditions using laboratory button cells. Oxygen electrodes based on various mixtures of La0.8Sr0.2MnO3-δ-ZrO2:Y2O3 were tested to prove that La1-xSrxMnO3-δ may become a mixed ionic-electron conductor under specific conditions.The obtained data showed that conditions, such as oxygen partial pressure, temperature and, in particular, the polarization history, could result in a partial reduction of Mn4+ to Mn2+ in the crystal lattice of La1-xSrxMnO3-δ. The change of valence is of a great importance because it creates oxygen vacancies through which oxide ions can be transported. Therefore, under such conditions La1-xSrxMnO3-δ becomes a partial mixed ionic-electron conductor, significantly increasing the number of active reaction sites in the three-dimensional structure of the electrode. The most recent articles reported this behavior; however, only during the oxygen reduction reaction owing to the most suitable conditions for the Mn oxidation state transition. Within the framework of this study, the aim is to expand this concept also to the conditions of the oxygen evolution reaction, which has been completely omitted in the literature. The presented results significantly contribute to the understanding of solid oxide cells and represent a solid base for further modelling of the electrolysis cell, and optimization of its construction as well as operational conditions.This work was supported by the Technology Agency of the Czech Republic under project no. TK04030143.

The neutron diffraction experiments under high pressure and high temperature on FENGHUANG diffractometer at CMRR

FENGHUANG diffractometer at CMRR, a high-intensity multi-section neutron powder diffractometer, has been constructed to in situ studies of materials under high pressure high temperature conditions. With development of anvils, high pressure high temperature cell assemblies, high pressure device and alignment system, we have been realized the angle-dispersive neutron diffraction data collect at the range of achievable pressures and temperatures of 0–30 GPa and 300–1500 K, with the sample size of millimeter scale. This paper describes the technical characteristics of diffractometer and related techniques for high pressure neutron diffraction experiments, and gives some scientific examples that have been recently performed on FENGHUANG. The experience gained experiments on FENGHUANG could help promote the development of high pressure techniques on neutron scattering facilities.

Numerical Study of the Flow Field Distributor in High-temperature Proton-exchange Membrane Fuel Cells

Numerical Study of the Flow Field Distributor in High-temperature Proton-exchange Membrane Fuel Cells

Thermo-fluid dynamics modelling of steam electrolysis in fully-assembled tubular high-temperature proton-conducting cells

Electrolysis based on renewable energies offers a promising carbon-free solution for hydrogen generation and storage. The recent developments of proton ceramic electrolysis cells operating at intermediate temperatures bear promise of superior energy efficiency compared to oxide ion conducting electrolytes. Here, a proton ceramic Single Engineering Unit (SEU) design is optimized for steam electrolysis using a computational fluid dynamics (CFD) model implemented in a COMSOL Multiphysics software. The SEU is an all-in-one tubular cell arrangement that constitutes the smallest electrolysis unit and enables efficient, adaptable pressurized hydrogen generation. The parametrical modelling study is conducted for two adiabatic operation scenarios with distinct steam conversion rates and tested for multiple key parameters, namely internal and external chamber pressures and inlet stream temperature. The modelling results show that low steam conversions enable operation at higher current densities and that the thermoneutral voltage for a fixed steam conversion is highly sensitive to the process conditions and operation modes. The increment of the pressure of the generated hydrogen implies a reduced production rate at thermoneutral voltage, although it can be compensated with an enhanced steam pressure or a reduced inlet temperature. Additionally, the introduction of a porous medium as the SEU current collector in the steam chamber enhances heat transport within this chamber. The area specific resistance of the system determines the current density, enforcing an adaption of the area of the electrolyser to satisfy the target hydrogen production and energy efficiency. The resulting proposed SEU design and adapted operational parameters allow effective delivery of pressurized dry hydrogen for a wide range of conditions and applications.

Electrochemical Analysis of Polymer Membrane with Inorganic Nanoparticles for High-Temperature PEM Fuel Cells

In order to solve the challenge that battery performance rapidly deteriorates at a high temperature condition of 100 °C or higher, ZrO2-TiO2 (ZT) with various Zr:Ti ratios synthesized by a sol-gel method were impregnated in a Nafion membrane. Through material characterization, a unique ZT crystal phase peak with a Zr-O-Ti bond was identified, and the band range associated with this bond and intrinsic functional group region could be identified. These prepared powders were blended with 10% (w/w) Nafion-water dispersion to prepare composite Nafion membranes (NZTs). The water uptake increased and the ion exchange capacity decreased as the TiO2 content increased in the NZTs in which particles were uniformly distributed. These results were superior to those of the conventional Nafion 112. The electrochemical properties of all membranes was measured using a polarization curve in a single cell with a reaction area of 9 cm2, and the operating conditions in humidified H2/air was 120 °C under 50% relative humidity (RH) and 2 atm. The composite membrane cell with nanoparticles of a Zr:Ti ratio of 1:3 (NZT13) exhibited the best electrochemical characteristics. These results can be explained by the improved physicochemical properties of NZT13, such as optimized water content and ion exchange capacity, strong intermolecular forces acting between water and nanofillers (δ), and increased tortuosity by the fillers (τ). The results of this study show that the NZT membrane can replace a conventional membrane under high-temperature and low-humidity conditions. To examine the effect of the content of the inorganic nanomaterials in the composite membrane, a composite membrane (NZT-20, NZT-30) having an inorganic nano-filler content of 20 or 30% (w/w) was also prepared. The performance was high in the order of NZT13, NZT-20, and NZT-30. This shows that not only the operating conditions but also the particle content can significantly affect the performance.

A new Concentrated Photovoltaic Thermal-Hydrogen system with photocatalyst suspension as optical liquid filter

Although typical Concentrated Photovoltaic-Thermal systems can overcome high cell temperatures, the low-level heat generated not only increases the irreversible energy loss but also narrows the application scope of the system. Here, we established a new Concentrated Photovoltaic Thermal-Hydrogen system coupling the Pt loaded TiO2 nanoparticle suspension, serving as both a photothermal hydrogen catalyst and an optical liquid filter for spectrum beam splitting, with a GaInP/GaAs/Ge triple-junction photovoltaic cell connected to an electrolytic cell to achieve full-spectrum solar energy to hydrogen storage conversion. Besides the additional hydrogen production, the Concentrated Photovoltaic Thermal-Hydrogen system with spectral beam splitting of TiO2 suspension can reduce the cell temperature by 32.8%, increase the electrical power by 65.7%, and save 49% of the cell area at most, compared to the case without spectral beam splitting. Thermalization loss was also reduced, which, in turn, increased the photovoltaic electrical performance. The proposed system can produce hydrogen at a maximum solar-to-hydrogen efficiency of 14% when the TiO2 loading amount is 150 ppm. It is expected to provide a guiding reference for achieving full-spectrum and high-efficiency solar energy conversion.

Removal of Hematite Water-Based Filter Cake Using Hydrochloric Acid

The filter cake layer, which is essential to reduce the fluid invasion to the drilled formation, has been reported to be composed mainly of the weighting materials. The complete removal of this layer is recommended to restore the rock permeability. Hematite is one material that is used to create the filter cake. However, the cleanup of hematite-based filter cake has not been studied thoroughly. The objective of the work presented in this paper is to investigate the removal of hematite water-based filter cake using hydrochloric acid. Numerous solubility tests were conducted to study the different factors affecting the treatment of hematite such as temperature and particle size. Based on these results, the treatment duration and acid concentration were selected. The high-pressure high-temperature filtration cell was used to build the filter cake and to soak it in the treatment solution at 100°C. Even though the solubility is increasing with acid concentration, however, no significant improvement was noticed above 12.5 vol.% of HCl. The particle size distribution has a considerable effect on the treatment, and the solubility was found to be 86 wt.% for particles finer than 25 microns and 47 wt.% for particle sizes above 75 microns, all in 10 vol.% HCl. The temperature has a significant influence as the solubility doubled when the temperature increased from 75°C to 100°C. The solubility rate decreased with time and reached the maximum in 16 hours which has been taken as treatment duration. Using 12.5 vol.%, 91 wt.% of the filter cake was successfully removed. In the literature comprehensive study on the cleanup of hematite-based filter cakes is lacking. This research provides new insights into hematite removal and address the different factors that impact the treatment efficiency.

Wet-air co-electrolysis in high-temperature solid oxide electrolysis cell for production of ammonia feedstock

To significantly abate the carbon footprint in the conventional Haber-Bosch process, a novel approach based on wet air co-electrolysis in solid oxide electrolysis cell (SOEC) was proposed and evaluated in this study for sustainable single-step production of ammonia feedstock (i.e., H2/N2 mixture). An electrolyte-supported SOEC composed of LSCM-GDC cathode, SSZ electrolyte and LSCF-GDC anode was prepared and tested under various operation conditions. The current-voltage responses measured for wet air co-electrolysis were featured with three different regions which could be attributed to competitive and combinative effects of oxygen splitting reaction and water splitting reaction under wet air co-electrolysis operation. Gas chromatography (GC) analysis of the exit gas from the cathode chamber proved that high purity H2/N2 mixture had been produced successfully through the novel wet air co-electrolysis process. However, the obtained H2:N2 ratios were still much lower than the desired 3:1 ratio in the ammonia feedstock for the Haber-Bosch process. Further explorations will be made to increase the H2:N2 ratio in the produced gas mixture.

Experimental study of temperature distribution effect on proton exchange membrane fuel cell using multi-pass serpentine channels

The uniform temperature distribution is one of the key features to consider in proton exchange membrane fuel cells (PEMFC) to increase performance and minimize the local hot spot formation on the membrane for longer membrane life. This work experimentally investigates the performance and temperature distribution on a 70 cm2 PEMFC with 1, 3, and 6-pass serpentine flow channels. The experimental results revealed that the 3-pass serpentine configuration showed better performance with peak a power density of 0.279 W/cm2, and the corresponding values obtained in 1 and 6-pass configurations are 0.246 and 0.228 W/cm2, respectively. To establish the temperature distribution, 20 thermocouples were provided in cathode plate and the temperature at different locations is mapped. The maximum cell temperature in 3-pass serpentine is limited to 69.76 °C due to enhanced reactant distribution and temperature uniformity. However, in 1 and 6-pass serpentine, the higher cell temperature is reported due to low temperature uniformity compared to the 3-pass serpentine design.

Sustainability analysis and optimization of innovative geothermal-driven energy storage system for green production of H2, NH3, and pure O2

Significant increase of greenhouse gas emissions and the emergence of global warming have drawn more attention to the use of renewable energies. In the pursuit of this objective, a novel geothermal-driven system consisting of steam and organic Rankine cycles, high-temperature solid oxide electrolysis cell (SOEC), and thermoelectric generator (TEG), NH3 synthesis unit is proposed for power, NH3/H2/O2 productions. The produced hydrogen is completely consumed. Fraction of hydrogen produced by SOEC is injected into the boiler for power generation through the SRC, and the remaining is fed into an ammonia synthesis unit to produce NH3. Moreover, the TEG is used as the condenser to increase system efficiency through waste heat recovery. The proposed system is comprehensively analyzed from energy, exergy, economic, and sustainability perspectives. Also, parametric analysis is conducted to evaluate the effect of important design parameters such as geothermal mass fraction ratio, H2 mass fraction ratio, N2 feeding rate, ammonia reactor pressure, and temperature on the performance and economic indicators of the power plant. Furthermore, comparative multi-objective optimization via the evolutionary genetic algorithm (NSGA-II) is developed in MATLAB to optimize the energy system. Moreover, two different scenarios for the optimization process were considered to compare the optimum solution points with each other. The results show that considering sustainability index and total cost rate as the target functions, by assigning the (m2˙m˙10) = 250, ΔTpp = 11.83, j = 2400 A/m2 and (m˙24m˙23) = 0.76, the highest achievable sustainability index and minimum cost rate are 1.875 and 328.94 $/h, respectively. In the second scenario, by choosing the (m2˙m˙10) = 80, ΔTpp = 19.37, j = 2400 A/m2 and (m˙24m˙23) = 0.3, the rate of ammonia production and total cost rate are reported to be 522.66 kg/h and 300.59 $/h, respectively, when the rate of ammonia production and total cost rate are considered conflicting objectives.

Dispersing Agents Impact Performance of Protonated Phosphonic Acid High-Temperature Polymer Electrolyte Membrane Fuel Cells

The microstructure of ionomers plays a significant role in the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Here, we establish direct correlations between the properties of dispersing agents and the microstructure of a protonated phosphonic acid ionomer. Most importantly, the formation of the porous structure of a protonated phosphonic acid ionomer depends on the pKa of the liquid media. Namely, the acid–base interaction between the charged polymer and dispersing agents determines the porosity in the ionomer thin films. The HT-PEMFC performance increases with the level of porosity of the ionomer, as the pores enable fast reactant gas accessibility. This study concludes the importance of the pKa of ionomers’ dispersing media for the HT-PEMFC performance.

A Review of X-ray Photoelectron Spectroscopy Technique to Analyze the Stability and Degradation Mechanism of Solid Oxide Fuel Cell Cathode Materials.

Nondestructive characterization of solid oxide fuel cell (SOFC) materials has drawn attention owing to the advances in instrumentation that enable in situ characterization during high-temperature cell operation. X-ray photoelectron spectroscopy (XPS) is widely used to investigate the surface of SOFC cathode materials because of its excellent chemical specificity and surface sensitivity. The XPS can be used to analyze the elemental composition and oxidation state of cathode layers from the surface to a depth of approximately 5–10 nm. Any change in the chemical state of the SOFC cathode at the surface affects the migration of oxygen ions to the cathode/electrolyte interface via the cathode layer and causes performance degradation. The objective of this article is to provide a comprehensive review of the adoption of XPS for the characterization of SOFC cathode materials to understand its degradation mechanism in absolute terms. The use of XPS to confirm the chemical stability at the interface and the enrichment of cations on the surface is reviewed. Finally, the strategies adopted to improve the structural stability and electrochemical performance of the LSCF cathode are also discussed.

Investigation on the Impact of High-Temperature Calendar and Cyclic Aging on Battery Overcharge Performance

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;With the degradation of lithium-ion batteries, the battery safety performance changes, which further influences the safe working window. In this paper, the pouch ternary lithium-ion battery whose rated capacity is 4.2 Ah is used as the research object to investigate the impact of the high-temperature calendar and cyclic aging on tolerance performance. The overcharge-to-thermal-runaway test is performed on the fresh cell and aged cell (90% SOH). The inflection point of voltage for aged cells appears earlier than that of the fresh cell, while the voltage corresponding to the inflection point is the same for them, which means that the voltage at which lithium plating occurs is the same. However, the voltage plateau and the crest voltage before thermal runaway of aged cell are significantly higher than that of the fresh cell. Besides, ohmic heat, reversible heat, and side reaction heat make contribution to the thermal runaway triggering. Among them, the side reaction heat plays a dominant role. Moreover, the ratio of heat generated by side reactions increases with aging. Compared with fresh cells, the thermal runaway triggering temperature of the high-temperature aging cell is increased. However, the duration of high-temperature cyclic aging cell is reduced, while the duration of high-temperature calendar aging cell is increased. Furthermore, although the maximum temperature of the aged cell has not changed significantly, the maximum temperature rise rate is significantly reduced, which may be caused by the loss of active materials. The aim of this article is to provide guidance for the design of battery safety management systems.&lt;/div&gt;&lt;/div&gt;

Hydrothermal fluid flow triggered by an earthquake in Iceland

Microearthquake hypocenters were analyzed in the Krýsuvík geothermal area in SW-Iceland with data taken from two consecutive passive seismic surveys, 2005 and 2009. Five years prior to the 2005 survey, this area was struck by an earthquake initiating a major top-to-bottom fluid migration in the upper crust. We observe from our surveys a complex bottom-to-top migration of seismicity with time following this fluid penetration, suggesting the migration of a pore pressure front controlled by the upper-crust fracture system. We interpret these data as the time and space development of high-temperature hydrothermal cells from a deep upper crustal fluid reservoir in the supercritical field. These results provide an insight into the coupling mechanisms between active tectonics and fluid flow in upper-crustal extensional systems with high thermal flux.

Effects of Growth Stage on the Characterization of Enterotoxin A-Producing Staphylococcus aureus-Derived Membrane Vesicles.

Virulence factors, such as staphylococcal enterotoxin A (SEA), are contained within membrane vesicles (MVs) in the cell membrane of Staphylococcus aureus. In this study, the effects of the growth stage on quantitative and qualitative changes in the components contained in the MVs of S. aureus SEA-producing strains were examined. Changes in the expression levels of S. aureus genes were examined at each growth stage; phenol-soluble modulin (PSM) gene reached a maximum after 8 h, and the expression of cell membrane-related genes was decreased after 6 h. Based on these gene expression patterns, MVs were prepared at 6, 17, and 24 h. The particle size of MVs did not change depending on the growth stage. MVs prepared after culture for 17 h maintained their particle size when stored at 23 °C. The amount of SEA in the culture supernatant and MVs were not correlated. Bifunctional autolysin, a protein involved in cell wall biosynthesis/degradation, was increased in MVs at 17 h. The expression pattern of inflammation-related genes in human adult low calcium high temperature (HaCaT) cells induced by MVs was different for each growth stage. The inclusion components of S. aureus-derived MVs are selective, depend on the stage of growth, and may play an important role in toxicity.

Intermediate Temperature Solid Oxide Cell with a Barrier Layer Free Oxygen Electrode and Phase Inversion Derived Hydrogen Electrode

High-temperature solid oxide cells (SOCs) have fundamental advantages in efficiency and product rate over their low-temperature counterparts. However, the commercial development of SOCs is hindered by cost and reliability. To solve the issues, lowering the operating temperature of SOCs is deemed the best solution. Here we report on our effort toward intermediate temperature (IT) SOCs by developing a barrier layer free high-performance oxygen electrode and open structured hydrogen electrode. The results show that the new oxygen electrode provides reasonably good oxygen electrocatalytic activity at IT range for oxygen reduction and evolution reactions and the open structured hydrogen electrode provides low gas diffusion path for H2/H2O. However, at high electrolysis current density such as 1 A cm−2 and 650 °C, the present oxygen electrode delaminates after 200 h. The phase-inversion derived open structured hydrogen electrode helps gas diffusion but, in the meantime, reduces reactive sites. A proper balance of porosity and number of reactive sites is still needed for future hydrogen electrode development.