bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Surface-Scanning Detector Position on the Response of a Wireless Magnetoelastic Biosensor
Authors: Horikawa Shin , Du Songtao , Liu Yuzhe , Lu Xu , Chen I-Hsuan , Wikle Howard Clyde , Chen Pengyu , Beidaghi Majid , Suh Sang-Jin , Feng Yucheng , Cheng Zhongyang , Chin Bryan Allen
Published: February 2020

This paper investigates the effects of surface-scanning detector position on the resonant frequency and signal amplitude of a wireless magnetoelastic (ME) biosensor for direct pathogen detection on solid surfaces. The experiments were conducted on the surface of a polyethylene (PE) plate as a model study. An ME biosensor (1 mm × 0.2 mm × 30 µm) was placed on the PE surface, and a surface-scanning detector was brought close and aligned to the sensor for wireless resonant frequency measurement. The position of the detector was accurately controlled by using a motorized three-axis translation system (i.e., controlled X, Y, and Z positions). The results showed that the resonant frequency variations of the sensor were -125 to +150 Hz for X and Y detector displacements of ± 600 µm and Z displacements of +100 to +500 µm. These resonant frequency variations were small compared to the sensor's initial resonant frequency (< 0.007% of 2.2 MHz initial resonant frequency) measured at the detector home position, indicating high accuracy of the measurement. In addition, the signal amplitude was, as anticipated, found to decrease exponentially with increasing detection distance (i.e., Z distance). Finally, additional experiments were conducted on the surface of cucumbers. Similar results were obtained.
(Invited) An Expanding Role for Sensor Research in Agriculture, Natural Resources, and Food Systems
Authors: Bewick Thomas A , Thomson Steven J
Published: February 2020

An Expanding Role for Sensor Research in Agriculture, Natural Resources and Food Systems. Thomas A. Bewick and Steven J. Thomson USDA National Institute of Food and Agriculture 800 9thSt SW Ste. 3146 Washington DC 20024

As the body of scientific knowledge concerning sensors continues to expand, new uses for sensors in agricultural and natural resource systems is a significant focus for USDA science agencies. Since 2008, this focus has intensified and there are now extramural funding programs, such as the National Robotics Initiative and the Cyber-Physical Systems Initiative, designed to specifically address this area of science. Other extramural funding programs, such as the Specialty Crop Research Initiative, also have expanded emphasis on the use of sensors in agriculture.

Agriculture is the pragmatic application of knowledge to complex biological systems. In order to meet current and future challenges to agricultural production, non-traditional approaches to these production systems will be needed. Agricultural plants and animals communicate with each other and their environments in ways that are not immediately obvious to human senses. Artificial sensors can expand the human capacity to understand that communication, leading to novel strategies to increase agricultural efficiency.

Sensor research for agriculture must have a different focus than research in other areas. The development of sensors without a specific end use in mind will be of minimal value over time frames that are useful to agricultural practitioners. This fact necessitates the collaboration of diverse scientific teams that include physical scientists, engineers, mathematicians, and social scientists working with biologists to understand how sensors can be applied to agricultural challenges. As the use of sensors in agricultural production increases, data management will become increasingly important, as will the development of decision support systems.
Continuous Flow Processes As an Advanced Manufacturing Platform for Electrolyte Materials
Authors: Dzwiniel Trevor L , Pupek Krzysztof Z. , Krumdick Gregory
Published: February 2020

New electrolyte materials (solvent, salt, additives) are required to enable HE/HV cells and to improve battery performance and safety. An advanced electrolyte solvents that allow for a wide electrochemical window and have low flammability (higher flash point) are the key components of a superior electrolyte. Continuous flow processes, an emerging technology in chemical industry offer an advanced manufacturing platform for electrolyte materials

The flexible modular design of the flow reactor system allows for various chemistries and conditions not feasible in a batch process. The processes are cost and energy efficient and adhere to other principles of green chemistry including improved safety.

The presentation will discuss continuous processes for manufacturing advanced electrolyte solvents via catalytic transesterification and catalytic hydrosylilation.
Towards Solventless Processing of Thick Electron-Beam (EB) Cured Lithium-Ion Battery Electrodes
Authors: Du Zhijia , Janke Christopher J , Li Jianlin , Daniel Claus , Wood David L
Published: February 2020

The development of high energy density and low cost Li-ion batteries is important for portable electronics and electric vehicle applications. It has been reported that electrode processing, especially for the cathode, with conventional manufacturing methods accounts for considerably high cost in Li-ion batteries [1,2]. Electrodes used in conventional lithium-ion batteries are manufactured through a slurry coating process, where a significant amount of solvent is required, and it takes at least several minutes for the solvent to evaporate. Given the high coating speeds necessary (up to 100 feet per minute) the drying zone may be several hundred feet long, which occupies a large footprint in battery manufacturing plants.

Here we propose manufacturing Li-ion battery cathodes using electron beam (EB) curing, which eliminates the using of solvents and allows the electrode to be cured at high speed. Solventless processing of powder coating and high speed curing at 500 feet per minute will also be discussed. Such a novel processing approach presents an exciting new avenue for manufacturing research of high performance, low cost Li-ion batteries.

Acknowledgements

This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) under contract DE-AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) Vehicle Technologies Office(VTO) (Deputy Director: David Howell) Applied Battery Research subprogram (Program Manager: Peter Faguy).

References:

[1] S. Ahmed, P. Nelson, K. Gallagher and D. Dees, J. Power Sources 322 (2016) 169.

[2] D. L. Wood, J. Li and C. Daniel, J. Power Sources 275 (2015) 234.
3D LiMn2O4 Electrodes for High Rate Thin-Film Microbatteries
Authors: Labyedh Nouha , Timmermans Marina Y. , Vereecken Philippe M.
Published: February 2020

3D thin-film microbatteries are attracting a lot of interest due to their fast charging capability and higher capacity provided by the surface area enhancement. The thin-film deposition techniques (e.g. RF-sputtering and CVD) typically used in case of planar thin-film microbatteries cannot be used for the 3D microbatteries. Indeed, for the latter, the thin-film needs to be conformally coated over high aspect ratio microstructured substrates which cannot be done using line-of-sight sputtering techniques. In this paper, we report on a new conformal thin-film fabrication technique for the preparation of 3D LiMn2O4 (LMO) thin-film electrodes. LiMn2O4 is an interesting cathode material for Li-ion batteries due to its high capacity and low volume change during the Li-ion insertion/extraction process. Moreover, the cubic spinel structure of LMO helps reaching a fast charging which is one of the key requirements for 3D thin-film batteries. Our novel fabrication technique is based on the electrochemical deposition of MnO2 thin-film and its conversion upon thermal treatment to LiMn2O4 using a Li2CO3 precursor.

Using this fabrication technique up to 350 nm conformal and continuous LMO films were prepared on different current collector materials both on planar substrates and on Si pillar arrays as 3D substrates providing an area enhanced of 21x (see SEM images in figure 1 (a, b, and b’)). Elastic recoil detection (ERD) analysis show that the fabricated films indeed have a stoichiometry close to the theoretical stoichiometry of LiMn2O4 and with a homogeneous element distribution throughout the layer. The prepared planar and 3D LMO thin-film are electrochemically active with comparable rate performance. The full theoretical capacity is reached at 0.1 C and 55% of the capacity is still retained at high C-rates of 10C (see figure 1 (c)). As expected from the area enhancement, the capacity for the 3D LMO electrode is 21 times that of planar LMO electrode.

Finally, a functional solid-state Li-ion battery was demonstrated using our 3D LMO thin-film cathode and a Li-foil anode using a nanocomposite solid electrolyte (SCE).

Figure 1
High Temperature Thermal Shock Synthesis of Catalyst-Decorated Nanostructures for Energy Storage
Authors: Lacey Steven David , Yao Yonggang , Xie Hua , Hu Liangbing
Published: February 2020

An efficient and ultrafast method to synthesize well-dispersed functional nanoparticles with controlled size and distribution remains largely unanswered. Conventional synthesis methods (wet chemistry, spray pyrolysis, among others) tend to be less controllable, leading to nanoparticle aggregation as well as a wide particle size distribution. Therefore, a short synthesis duration is critical to control nanoparticle size and minimize aggregation.

Here we report a rapid and universal high temperature thermal shock method to form and uniformly disperse metallic nanoparticles on a conductive carbon support, such as carbon nanofibers (CNF). First, the desired metal salt precursor is homogeneously mixed into an aqueous solution and loaded onto the conductive carbon support. After drying, the precursor-loaded CNF film is attached to electrical leads inside an argon-filled glovebox to facilitate the electrically triggered Joule heating procedure. An applied electrical pulse from an external power source induces the thermal shock process by heating the precursor-loaded CNF to ~2000 K for mere milliseconds at ultrafast heating/cooling rates (~105 K/s). Due to the short high temperature exposure and rapid cooling rate, nearly any precursor metal salt can decompose and nucleate into uniformly distributed metallic nanoparticles with ultrafine particle sizes without damaging the conductive support. Note that kinetic control can also be achieved by tuning the synthesis parameters (pulse duration, heating temperature, heating/cooling rates). Specifically, as the pulse duration increases to seconds, the temporal limitations for diffusion and migration broaden, allowing nanoparticles with larger diameters to form with a wider particle size distribution.

In the field of energy storage, nanoparticle-decorated conductive supports are ideal battery electrodes. To demonstrate the proposed manufacturing method, lithium-oxygen (Li-O2) batteries were successfully assembled and tested using the nanocatalyst-decorated CNF films. Bifunctional ruthenium nanoparticles were synthesized by the rapid thermal shock method to increase the electrocatalytic activity of the CNF-based Li-O2 cathodes and improve oxygen reaction kinetics. The results indicate the potential of this rapid manufacturing method to synthesize an array of non-agglomerated nanoparticle-decorated supports for energy storage devices and beyond.
Redox Reaction on the Surface/Edge Strturtures of Graphene/Graphite
Authors: Kumatani Akichika , Miura Chiho , Shiku Hitoshi , Yasufumi Takahashi , Matsue Tomokazu
Published: February 2020

Graphene, a single atomic layer of graphite, has been widely studied because of its unique electrical, optical, electrochemical, and elastic properties. With respect to the electrochemical property, it is also expected for energy harvesting and storage applications such as hydrogen generation for fuel cells and ion transport for secondary batteries. Indeed, the graphene’s exotic phenomena come from its ideal structure such as edge states, two-dimensional surface, defects. To understand their intrinsic mechanism due to structure effects, it is required to analyze and visualize their electrochemical reaction by a spatially resolved electrochemical analysis technique at microscopic scale. In general, electrochemical analytical tools are conducted at mesoscopic scale. Scanning probe microscopies have been also utilized for analyzing their properties to satisfy the issue in resolution. Scanning tunneling microscopy and conductive atomic force microscopy can analyze at atomic scale precisely, but their information is mainly limited to electronic properties which do not directly reflect to their electrochemical properties. In this study, to overcome the issue, scanning electrochemical cell microscopy with sub-micrometer resolution, i.e. nanoSECCM, was utilized as a direct technique for electrochemical reactions [1]. A glass nano-pipette was applied as a probe. The pipettes were filled electrolyte and a reference electrode (5 mM hexaammineruthenium chloride and 25 mM KCl in phosphate buffer or deionized water for electrolyte, Ag/AgCl for a reference electrode). The nanoSECCM was applied to cleaved graphite or graphene on silicon substrates. When the pipette was approached to the sample surface, a meniscus was created as an electrochemical cell. Through the cell, redox reaction of ruthenium ion inside electrolyte was measured. By scanning the pipette with the same process at next measurement location, redox reaction on the graphene/graphite surface were visualized as shown in Fig 1.

[1] Y. Takahashi, A. Kumatani et al. Nat. Comm. 5:6450 (2014).

Figure 1
Impedance Response of Corrosion Monitoring Sensor Fabricated By Screen-Printing Technique
Authors: Fujii Naoto , Aiba Akihiro , Hoshi Yoshinao , Shitanda Isao , Itagaki Masayuki
Published: February 2020

A miniaturization of wiring on the printed circuit board is important role for the development of microelectronic devices. However, it may easily lead to the electrical short circuit of the wiring on the printed circuit board in wet and dry conditions. Thus, development of corrosion monitoring sensor is necessary. Motoda et al. 1) developed an atmospheric corrosion monitor (ACM) censer. It was composed of two different metal electrodes (Fe and Ag), and the both electrodes were insulated each other. In this case, the electrochemical signals were measured due to the generation of the thin water film on the ACM censer. Shitanda et al. 2) reported an electrochemical sensor fabricated by screen-printing technique. They 2) applied an electrochemical impedance spectroscopy for monitoring the impedance of electrochemical sensor during wet and dry conditions. They 2) mentioned the application of electrochemical sensor fabricated by screen-printing technique for corrosion monitoring of printed circuit boards.

In this study, a corrosion monitoring sensor (CMS) was fabricated by the screen-printing technique. The impedance of the CMS was measured by a two electrode system. A 15 mg cm-2 NaCl was dispersal on the CMS before the measurement. The temperature and relative humidity were kept at 25 ℃ and 90 % in a thermostatic chamber during the measurement. The impedance of CMS was measured during wet and dry conditions due to the deliquescence of NaCl. The impedance measurement was carried out for 17.5 hours. The DC voltage was open circuit voltage. The voltage amplitude was 10 mV. The frequency range of the impedance was from 10 mHz to 10 kHz. After the impedance measurement, the CMS was dried at 60 ℃ . In addition, the impedance of CMS was also measured at room temperature after drying.

The impedance of CMS was measured every 2.5 h, indicating that a loop related to the electrode/solution interface was observed on the Nyquist plane. The magnitude of impedance at each time was discussed with the generation of the water film on the CMS during measurements.

Reference

[1] S. Motoda, Y. Suzuki, T. Shinohara, Y. Kojima, S. Tujikawa, W. Oshilawa, S. Itomura, T. Fukushima, S. Izumo, Zairyo-to-Kankyo, 43,550 (1994).

[2] I. Shitanda, A. Okumra, M. Itagaki, K. Watanabe, Y. Asano, Sensors and Actuators B: Chemical ,139, 292 (2009).
Nano-Oxide Dispersed Ferritic Stainless Steel for Metallic Interconnects of Solid Oxide Fuel Cells
Authors: Mehran Muhammad Taqi , Song Rak-Hyun , Lee Jung-Won , Khan Muhammad Zubair , Lee Seung-Bok , Lee Jong-Won , Lim Tak-Hyoung , Hong Jong-Eun , Park Seok-Joo
Published: February 2020

For long-term operation of solid oxide fuel cells, ferritic stainless steel-based metallic interconnects with high durability are considered to be one of the most viable materials. However, the formation of a thick chromia layer during the long-term operation results into an increase in the area specific resistance (ASR), ultimately shortening the lifetime of the SOFC [1, 2]. In this study, we developed novel nano-oxide dispersed ferritic steel SUS430 based alloys and tested their long-term performance as interconnect materials for SOFC application. Nano-oxides of CeO2, LaCrO3, and Y2O3 (particle size <50 nm) were dispersed into the commercial SUS430 powder by using high-energy ball milling in specific binder and solvent conditions to get a uniform distribution. The highly dense rectangular pellets specimens were prepared by uniaxial and then cold isostatic pressing (CIP) methods, followed by sintering in H2 at 1400 oC for 10 h. Physical properties, microstructural and phase analysis of the sintered nano-oxide dispersed stainless steel alloys were examined before the long-term testing. The developed alloy samples were tested for oxidation characteristics and long-term ASR behavior in air at 800 oC for 1000 h. Post-test analysis of the samples were conducted by SEM, EDS, and XRD techniques. The long-term ASR results show that the dispersion of nano-oxide particles significantly improved the ASR properties of the ferritic stainless steel based alloys. Especially, the total increase in the ASR of nano-CeO2 dispersed ferritic steel during the 1000h long-term test was much less than that of the SUS430, comparable to one of Crofer APU22. LaCrO3 addition also improved the ASR property but Y2O3 dispersion did not so. The dispersed nano-oxides decreased the grain size of the ferritic steel and the oxide particles were distributed at the grain boundaries of the steel. In this work, these electric and oxidation behaviors for long-term test were discussed as related to the microstructure, oxide scale formation mechanism and nano-oxide distribution of the samples.

References:

[1] L. Niewolak, F. Tietz, W.J. Quadakkers, Interconnects, in: K. Kendall, M. Kendall (Eds.), High-Temperature Solid Oxide Fuel Cells 21st Century, 2nd ed., Academic Press, Boston, 2016: pp. 195–254.

[2] N. Shaigan, W. Qu, D.G. Ivey, W. Chen, A review of recent progress in coatings, surface modifications and alloy developments for solid oxide fuel cell ferritic stainless steel interconnects, J. Power Sources. 195 (2010) 1529–1542.
MCO-Coated Interconnects for Mitigation of Cr-Poisoning in Solid Oxide Fuel Cells
Authors: He Hongpeng , Benhaddad Sofiane , Steedman Dale , Chen Chen , Krivy Mark
Published: February 2020

Chrome species evaporated from stainless steel interconnect are considered to be the major poisoning source for the cathode of solid oxide fuel cells (SOFCs). The poisoning effect is extremely severe when humidity is present in the incoming air. High performance perovskite-oxide type cathodes, such as LSCF and BSCF are subject to deactivated by Cr. To eliminate/mitigate the Cr poisoning effect, thin film coatings on the surface of stainless steel (SS) are employed to block Cr evaporation. In the present study, a Mn-Co oxide (MCO) thin film coating on SS using the dip coating method will be reported. Dip coating was found to be very suitable to fabricate MCO coatings on SS, which in the case of SOFC interconnects are usually specially designed for gas delivery with complex structure. The initial results indicate MCO thin film is very effective in blocking Cr evaporation, which was examined in both single cell and stack testing. Single cell tests using MCO-coated cathode SS test hardware resulted in a very low degradation rate of < 4 mV / 1000 hours when tested over thousands of hours with up to 10% cathode humidity. This result is very similar to tests without humidity. Stack testing indicates dip coating is feasible for coating specially designed, complex parts such as SOFC interconnects.

Key words: SOFC, dip coating, MCO
Electrically Conductive and Protective Coating for Planar SOFC Stacks
Authors: Choi Jung Pyung , Stevenson Jeffry W
Published: February 2020

Ferritic stainless steels are preferred interconnect materials for intermediate temperature SOFCs because of their resistance to oxidation, high formability and low cost. However, their protective oxide layer produces Cr-containing volatile species at SOFC operating temperatures and conditions, which can cause cathode poisoning. Electrically conducting spinel coatings have been developed to prevent cathode poisoning and to maintain an electrically conductive pathway through SOFC stacks. However, this coating is not compatible with the formation of stable, hermetic seals between the interconnect frame component and the ceramic cell. Thus, a new aluminizing process has been developed by PNNL to enable durable sealing, prevent Cr evaporation, and maintain electrical insulation between stack repeat units. Hence, two different types of coating need to have stable operation of SOFC stacks. This paper will focus on the electrically conductive coating process. Moreover, an advanced coating process, compatible with a non-electrically conductive coating will be shown.
Electrochemical Behavior of Nanostructured La0.8Sr0.2MnO3 as Cathodes for Solid Oxide Fuel Cells
Authors: Sacanell Joaquín , Hernández Sánchez Joaquín , Rubio Lopez Adrián Ezequiel , Martinelli Hernán , Siepe Jimena , Leyva Ana Gabriela , Ferrari Valeria Paola , Pruneda Miguel , Juan Dilson , Lamas Diego German
Published: February 2020

In this work we outline the mechanisms contributing to the oxygen reduction reaction in nanostructured cathodes of La0.8Sr0.2MnO3 (LSM) for Solid Oxide Fuel Cells (SOFC). These cathodes, developed from LSM nanostructured tubes, can be used at lower temperatures compared to microstructured ones, and this is a crucial fact to avoid the degradation of the fuel cell components. This reduction of the operating temperatures stems mainly from two factors: i) the appearance of significant oxide ion diffusion through the cathode material in which the nanostructure plays a key role and ii) an optimized gas phase diffusion of oxygen through the porous structure of the cathode, which becomes negligible. A detailed analysis of our Electrochemical Impedance Spectroscopy supported by first principles calculations point towards an improved overall cathodic performance driven by a fast transport of oxide ions through the cathode surface.

Figure 1
Development of High Efficient Multi Fuel Reversible Solid Oxide Electrolyzer Systems
Authors: Schauperl Richard , Defner Beppino , Rechberger Juergen , Soukup Nikolaus
Published: February 2020

Power-to-Gas-to-Power technologies offer strong potentials for energy markets with highly stochastic energy production from renewable sources, such as wind and PV. Increasing efficiencies and cost effectiveness are key issues in state of the art reversible solid oxide electrolyzes systems and still a major challenge. Using a reversible SOE system (rSOE), instead of two separate units that operate alternately for gas or power production, promises to be a very cost effective solution. The rSOEC system can switch between these two operation modes, which results in a more compact system that can be operated almost full time. Additionally, the system can be highly efficient operated with a whole range of different fuels, which increases the technologies flexibility and usability.

This multiuse and multifuel character of rSOE systems leads to very particular challenges in the development. A feasible concept has to combine all necessary BoP components and control mechanisms allowing all modes of operation, while keeping efficiencies and cost effectiveness. One particular challenge for the system design is heat management. A method was developed that promises best possible use of heat recirculation in all modes, while being minimal in design and regulation requirements. For the first time dynamic simulations for all operating conditions e.g. start-up, shut-down, stand-by and mode-switching processes, including all relevant mass and energy flows are currently developed. This strongly supports the system development by making them more effective, since iterative development circles and thus development time and hardware costs are reduced.

The project “Hydrocell” (2013-2016) demonstrated the usability of these simulation methods. A Proof-of-Concept SOEC system has been developed and tested with electricity to H2 (LHV) conversion efficiencies above 80%el.

Within the current project “AuRora”, various system designs for a fully autonomous rSOE system were identified. The concepts are switchable between H2O electrolysis, H20+CO2 co-electrolysis with system integrated catalytic methanation and multifuel SOFC operation. System concepts are developed with conversion efficiencies above 80%el* for H2 production and CH4 production. Based on the simulation results, including CFD, a 1kWelProof-of-Concept will be realized on the testrig in 2017.

Within the presentation, the theoretical background, different rSOE systems designs, optimized operation conditions, as well as measurements performed in the project “Hydrocell” and “AuRora” will be explained. This includes steam-electrolysis, H2O + CO2 co-electrolysis with system integrated catalytic methanation, SOFC operation with H2, as well as multifuel operation with system integrated fuel reformation.

* based on LHV energy content
LSM/YSZ Button Cell Tests in Cathode Air with Measured Cr Concentrations
Authors: Hardy John S , Coyle Christopher A , Neeway James J , Stevenson Jeffry W
Published: February 2020

A test fixture and methodology was developed for testing anode-supported SOFC button cells downstream from a chromia pellet placed in the cathode air stream at a prescribed temperature to control volatilization of Cr vapor species. A porous alumina foam coated with a Cr gettering material is then placed downstream from the cell to capture Cr from the cathode air stream. The Cr gettering coating is composed of Na2CO3, which reacts with Cr vapor species to form Na2CrO4. The coating and its reaction product are both water soluble which facilitates dissolving them from the porous substrate for subsequent ICP analysis to determine the concentration of the resulting aqueous solution. The mass of collected Cr can then be calculated and used to determine the average concentration in the known volume of air that flowed past the cathode over the duration of the test. Electrochemical tests of cells with LSM/YSZ cathodes were performed with the chromia pellet at varying conditions of temperature and humidity to elicit various levels of Cr volatility. Multiple cells were tested at each condition for 600 to 1000 hours. Molar concentrations of Cr in the cathode air as small as 4×10-11 were found to cause ~4%/kh degradation in performance.
Solid Oxide Fuel Cells: Opportunities for Economic Growth in Japan
Authors: Behling Noriko , Williams Mark C
Published: February 2020

A sustainable society literally means a society where citizens use as their primary energy source fuel produced primarily from renewable energy and use less fossil fuels. It attempts to transform an ordinary carbon society into a society that depends upon sustainable sources of energy. There is a need to establish a policy that will promote the development of renewable sources of methane and hydrogen for multiple applications, creating the foundations for a society where citizens can enjoy sustained economic growth, energy security, and environmental well-being. This paper will examine the challenges solid oxide fuel cell technology might encounter, the potential economic opportunities it might enjoy if the sustainable society policy succeeds, and recommends the policy be fully integrated with other initiatives that would promote economic growth, more efficient communities, and a cleaner environment.
Hole-Proton Mixed Conduction of Perovskite-Oxide Thin Film with Oxygen Vacancies and Lattice Distortion for SOFC Electrode
Authors: Higuchi Tohru , Furuichi Shoto , Namiki Wataru , Takayanagi Makoto , Minohara Makoto , Horiba Koji , Kumigashira Hiroshi , Tsuchiya Takashi
Published: February 2020

Acceptor-doped BaPrO3 bulk ceramic is a proton conducting material in the intermediate-temperature (IMT) region from 300 to 700 °C. In particular, the electrical conductivity at 500 °C of Gd3+- or Yb3+-doped BaPrO3 is ~1.0×101 Scm−
1 in wet atmosphere. Furthermore, the occurrence of electron (or hole)–ion mixed conduction, which is expected as the electrode material of a solid state fuel cell (SOFC) using an oxide proton conductor, has also been proposed in the IMT region of Yb3+-doped BaPrO3.

In this study, in-plane-oriented BaPrO3−δ thin film with mixed valence states has been prepared on an Al2O3(0001) substrate by RF magnetron sputtering. With increasing crystallization temperature (T
sub), the lattice constant decreases and the orientation changes from the a-axis to the b-axis. The thin film prepared above T
sub = 800 °C exhibits a higher proton conductivity than bulk ceramics. The conductivity below 400 °C decreases with oxygen gas partial pressure, indicating the existence of hole-ion mixed conduction. The valence band consists of O 2p states hybridized with the Pr4+ (4f
0) and Pr3+ (4f
1
L) states, which are closely related to the mixed conduction. The energy difference between the top of the valence band and the Fermi level corresponds to the activation energy of holes for the total conductivity below 400 °C.
The Role of Cathode Current Contact on the Performance of Full-Size Cells and Stacks
Authors: Guan Wanbing , Zhou Xiao-Dong
Published: February 2020

Much research on solid oxide fuel cells (SOFCs) has adopted the configuration of button cells or symmetric half cells, which enable the investigations of SOFC constituents, such as the electrolyte and electrodes. The performance of SOFCs of a full-cell size (e.g. 10 cm ´ 10 cm) or a stack is highly dependent upon the cathode current collector, which bonds the cathode with a metallic interconnect. The requirements for the contact material are (1) sufficiently high electrical conductance, (2) compatibility with the cathode and interconnect materials with respect to CTE, (3) chemical stability under high current conditions, (4) ability to buffer the interactions between interconnect oxide and electrode oxide, and (5) stability with both interconnect and cathode and not adversely affect the formation of the interconnect protective oxide. In this presentation, we will describe the mechanism that the cathode current collector affects the cell performance by using full-size cells and short-stacks. The area specific resistance of the cathode current collector was studied by changing the contact material, gas distribution in the interconnect, anode contact materials, gas flow rate, fuel utilization ration and operation temperature.

The author would like to thank the financial support from Natural Science Foundation of China (No. 51502316) and Excellent Members of Youth Innovation Promotion Association, CAS (No. Y50708WR28). The work was partially supported by US DOE through DE-FE0026097.
Barium Oxide (BaO) Infiltrated Lanthanum Strontium Manganese Oxide (LSM)-Gadolinium Doped Ceria (GDC) Solid Oxide Electrochemical Reduction Cells (SOERC) for Reduced Diesel NOx Emissions
Authors: Zhang Yubo , Nicholas Jason D.
Published: February 2020

Diesel engines are widely used in automobiles for their high fuel efficiency, low carbon monoxide emissions, and low hydrocarbon emissions [1]. Unfortunately, due to their lean-burn operating environment, diesel engines emit higher amounts of NOx than gasoline engines. Although NOx Storage and Reduction (NSR) and Selective Catalytic Reduction (SCR) technologies have been commercialized and offer high deNOx (i.e. NOx decomposition) efficiency, they suffer from a loss of fuel efficiency during catalyst regeneration and a need for large-volume, on-board ammonia storage and replenishment, respectively [2]. Further, expensive precious metal catalysts are needed to enable deNOx chemical reactions in these conventional technologies. In contrast, Solid Oxide Electrochemical Reduction Cells (SOERCs) utilizing an external bias to electrochemically drive NOx decomposition promise precious-metal-free operation without the need for catalyst regeneration or large-volume, on-board storage.

Here, the deNOx performance of barium oxide (BaO) infiltrated lanthanum strontium manganese oxide (LSM)-gadolinium doped ceria (GDC) SOERCs were measured as a function of operating temperature, AC amplitude, and AC frequency. Under all test conditions, SOERC performance was reproducible across different samples with the application, removal, and subsequent reapplication of electrical bias. The BaO-LSM-GDC SOERCs tested here displayed better low-temperature NOx conversion efficiencies than those previously reported in the literature; achieving 22% at 350oC compared to the 3% reported in the literature [3, 4]. In agreement with this literature 1) the application of an AC electric bias was found to produce higher BaO-LSM-GDC NOx conversion efficiencies than a DC bias of the same magnitude, and 2) BaO-LSM-GDC SOERCs exhibited current and thermodynamic efficiencies of a few percent, and a few tenths of a percent, respectively. Unfortunately, as shown previously [3, 4], these conversion efficiencies decreased by several percent after only a few hours of operation at 450oC due to microstructural coarsening of the BaO infiltrate.

References

[1] D.B. Kittelson, Journal of Aerosol Science, 29 (1998) 575-588.

[2] W.S. Epling, L.E. Campbell, A. Yezerets, N.W. Currier, J.E. Parks, Catalysis Reviews, 46 (2004) 163-245.

[3] J. Shao, K.K. Hansen, Journal of Materials Chemistry A, 1 (2013) 7137-7146.

[4] J. Shao, K.K. Hansen, Journal of the Electrochemical Society, 160 (2013) H494-H501.
Fuel Cells Operating at 200 to 500 Celsius: Lessons Learned from the ARPA-E REBELS Program
Authors: Litzelman Scott J. , Pouy Mark J. , Albertus Paul S. , Soloveichik Grigorii L.
Published: February 2020

In 2014, the Advanced Research Projects Agency-Energy (ARPA-E) launched the Reliable Electricity Based on ELectrochemical Systems (REBELS) program with the goal of pursuing alternate fuel cell materials and operating conditions that could enable system cost reductions and new electrochemical functionality. This presentation will briefly revisit the original REBELS vision by elaborating the potential benefits of operation in an intermediate temperature range of 200-500 C. Trends in the U.S. electrical grid will be discussed, which reveal the benefits of enhanced fuel cell functionality such as in-situ charge storage and gas-to-liquids (GTL) capabilities. The most significant technical accomplishments from REBELS project teams will be highlighted, including several examples in which the program objective of a current density of 200 mA/cm2 at 0.78 V and 500 C on methane fuel was achieved. Furthermore, teams were able to demonstrate thousands of hours of operation on internally-reformed methane fuel at 500 C with no evidence of coke formation. Fuel cells with charge storage functionality in or near the anode showed a more rapid response to large changes in current density and a lower voltage decrease with high fuel utilization. The needs for further techno-economic assessment to evaluate this concept will be highlighted. Progress towards fuel cells that can also convert methane to liquid fuels will be summarized. Finally, overall lessons learned from the REBELS program will be discussed, such as the ability of ceramic proton conductors to deliver high current density at 500 C on non-hydrogen fuels with minimal degradation. The need for future work in this field will be stressed, especially a continued examination of whether stacks in this temperature range possess the appropriate combination of performance and cost to accelerate the commercialization of high efficiency fuel cells worldwide.
High Performance Solid Oxide Electrolysis Cells with Hierarchically Porous Ni-YSZ Electrode
Authors: Lei Libin , Chen Yu , Zhang Yanxiang , Liu Tong , Wang Yao , Chen Fanglin
Published: February 2020

In solid oxide electrolysis cells (SOECs), the microstructure of the cathode (Ni-YSZ) has a great influence on the electrochemical performance of cells. In this study, novel hierarchical Ni-YSZ electrode substrates with open channel pores have been fabricated by freeze-drying tape casting (FTC). The microstructure characterization of the the Ni-YSZ electrode substrates, using SEM, mercury intrusion, 3D X-ray microscopy and gas permeability, shows that Ni-YSZ electrode substrates fabricated by FTC have large porosity and low tortuosity factor, which are beneficial for gas transport. The SOECs with the Ni-YSZ electrode substrates fabricated from FTC display excellent performance ( -0.95 A cm-2 with 1.3 V at 750 oC) in the electrolysis mode, which is twice of those with the conventional sponge-like Ni-YSZ electrode substrate fabricated from dry-pressing. Furthermore, compared with the cell performance in the fuel cell mode, the advantages of the hierarchically porous Ni-YSZ electrode substrates are more obvious in the electrolysis mode, which may be due to the slower diffusion of H2O and CO2, compared with H2.
Toward a New Generation of Intermediate-Temperature Fuel Cells
Authors: Liu Meilin , Chen Yu , Yoo Seonyoung , Rainwater Ben , Zhang Lei , deGlee Ben , Dolye Brian
Published: February 2020

Solid oxide fuel cells (SOFCs) have potential to be the cleanest and most efficient option for direct conversion to electricity and heat of a wide variety of fuels, from hydrogen to hydrocarbons, coal gas, and bio-derived fuels. However, their commercialization hinges on rational design of novel materials of exceptional functionalities at lower temperatures to dramatically reduce the cost while enhancing performance and durability. To accomplish this goal, it is imperative to gain a fundamental understanding of the mechanisms of charge and mass transport along surfaces, across interfaces, and through porous electrodes in fuel cell systems. Further, new protocols must be developed to control materials structure, composition, and morphology over multiple length scales, thus producing nano-porous materials with more accessible surfaces of much higher functionalities and with shorter diffusion distances for greatly enhanced rate capabilities. Recently, we have fabricated and tested an electrode architecture derived from nanofibers of active cathode materials with enhanced electrochemical performance, multifunctional anodes with oriented porosity, nanostructured Sm-doped ceria electrolyte membranes with high ionic conductivity, and thin-film samples of proton and oxygen ion conducting electrolytes to study nanoionics effects at heterogeneous interfaces. This presentation will highlight the critical scientific challenges facing the development of a new generation of ITFCs, the latest developments in mixed-ion conducting electrolyte materials, nano-fiber-based cathodes, and catalytically-active anodes for internal reforming of methane at relatively low temperatures, and the perspectives for future-generation fuel cells that exploit nano-scale materials of significantly improved performance.
A Preliminary Study on Bi-Layered Ceramic Electrolytes of Mixed Conductor and Proton Conductor
Authors: Zhang Xinge , Robertson Mark , Deces-Petit Cyrille
Published: February 2020

In this contribution, we present an experimental study of single-layered electrolyte with mixed ion and electron conducting ceramic material SDC (Sm0.2Ce0.8O2-x) and bi-layered electrolyte of the SDC layer with proton conducting ceramic material BCY (BaCe0.9Y0.1O3-x) to enhance the electrolyte performance. Anode supported cell structure was adopted and the button cells were fabricated through conventional tape casting-screen printing and high temperature sintering processes. It was found that the open circuit voltages of the bi-layered electrolyte cells were higher than that of the single-layered SDC electrolyte cells. The bi-layered cells showed a decent performance in the temperature range of 500-650°C. Interaction between the two electrolyte materials occurred at high sintering temperature, which led to an increase in electrolyte resistance as well as electrode polarization values.
A Method for Quantitative 3D Mesoscale Analysis of Solid Oxide Fuel Cell Microstructures Using Xe-plasma Focused Ion Beam (PFIB) Coupled with SEM
Authors: Mahbub Rubayyat , Hsu Tim , Epting William K , Nuhfer Noel T. , Hackett Gregory A , Abernathy Harry , Rollett Anthony D , De Graef Marc , Litster Shawn , Salvador Paul A
Published: February 2020

Three-dimensional (3D) distributions of microstructural features in electrodes of solid oxide fuel cells (SOFCs) directly influence their electrochemical performance. Commercial grade SOFCs produced in cost-constrained environments can be expected to exhibit variations on the mesoscale (≈ hundreds of µm) of the microscale features (≈ tens of µm) that determine the local electrochemical activity. We are interested in quantitatively determining the mesoscale distributions of microscale properties in SOFC electrodes, especially quantifying the tails of distributions to establish correlations between such outliers and long-term performance. In this talk, we describe a new method that allows for the fast reconstruction of incredibly large volumes while maintaining a resolution on the order of tens of nm, allowing for fine-scale features to be accurately quantified. We use a Xe plasma focused ion beam (FIB) for slicing and a scanning electron microscope (SEM) for imaging. The pFIB allows for an increase in material removal rates by a factor of ≈ 100 compared to Ga ion FIBs, while the SEM resolution remains very high (herein ≈ 50nm), comparable to nano-CTs. In the same time as required for collecting Ga-FIB or nano-CT data sets, we collected a pFIB volume that is ≈ 70-80 times larger than attainable with Ga-FIB-SEM and ≈15-20 times larger than with nano-CT. From this data, we quantified the mesoscale distributions, containing both the mean and the variance, of key microscale features including volume fraction, average particle size, tortuosity, and triple phase boundary density. The commercial SOFC electrodes investigated were found to exhibit significant variations in the mesoscale distributions of their local microstructural features, which will be discussed. Importantly, these mesoscsale variations in microstructural features are expected to result in significant variations in electrochemical activity throughout the electrode. Using an effective medium theory model of polarization resistance, we quantified the distribution of microscale polarization resistance and mapped it spatially. Though the average value of polarization resistance is within range of expectation, the measoscale distribution of the microscale/local value of polarization resistance around the average indicates that several local areas are well outside the average, and potentially operating in regions expected to impact long-term cell performance.
CO2-Stable Alkaline-Earth-Free Solid Oxide Fuel Cells with Ni0.7Co0.3O-Ce0.8Sm0.2O1.9 Composite Cathodes
Authors: Lin Bin , Chen Yonghong , Cheng Zhuanxia , Yang Yang , Traversa Enrico
Published: February 2020

One of the main problems for the deployment of intermediate-temperature solid oxide fuel cells (IT-SOFCs) is their chemical stability, since most of SOFCs contain alkaline-earth metal elements (Ba, Sr and Ca) that easily react with CO2 forming carbonates. To tackle this problem, we performed a systematic investigation of a series of Ni0.7Co0.3O–Ce0.8Sm0.2O1.9 (NC3O-SDC) composite cathodes, which are CO2-stable and alkaline-earth-free compounds. In this work, NC3O-xSDC (with x = 0-60 wt.%) were synthesized by self-propagating combustion method and investigated as new cathode materials for oxygen-ion conducting SOFCs. The thermal stability and phase structure of NC3O polycrystalline powders were studied using TG-DTA and XRD analysis, which confirmed that NC3O is chemically compatible with SDC. The electrical conductivity and thermal expansion of the NC3O-xSDC samples were measured. The electrochemical properties of NC3O-xSDC/SDC/NC3O-xSDC cells were studied using electrochemical impedance spectroscopy measurements. Among the NC3O-xSDC series, NC3O-30SDC showed a minimum in cathode polarization resistance, being 0.071 Ωcm2 at 800. A maximum power density of 200 mWcm-2 at 600 was obtained using anode-supported SOFCs.
Characteristics of Electrochemical Conversion for Syngas Production by Tubular Solid Oxide Coelectrolysis Cell
Authors: Lim T. H. , Hong J. E. , Lee J. W. , Lee S. B. , Park S. J. , Song R. H.
Published: February 2020

The high temperature H2O/CO2 electrochemical conversion process using solid oxide coelectrolysis (SOC) cell is potentially an efficient way to reduce CO2 emission and to store renewable power simultaneously. In this study, the tubular solid oxide coelectrolysis (SOC) cell based on a general electrode support tube through an extrusion process, and the essential SOC cell, components, such as the electrolyte and the electrode, were then coated onto the surface of a ceramic support consecutively using a vacuum slurry and dip-coating method. The tubular SOC cell was operated while varying the operating temperature, cathode flow rate, and inlet H2O and CO2 composition. In this study, we have been conducted advanced and systematic experimental with the tubular SOC cell in order to experimentally approach. Electrochemical performance of tubular SOC cell is systematically investigated with various operating conditions such as operating temperature, inlet H2O or CO2 composition and analysis by I-V curve and EIS analysis. Finally, produced syngas is analyzed by gas chromatography through optimized operating conditions. The effect of operating conditions and syngas yields were discussed in detail.