bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase-Field Study of Sodiation of Snsb Thin Film Electrodes
Authors: Yurkiv Vitaliy , Gutiérrez-Kolar Jacob , Ramasubramanian Ajaykrishna , Shahbazian-Yassar Reza , Mashayek Farzad
Published: February 2020

Sodium-metal and sodium-metal alloys (metal = Sn, Sb, In, Ge) are very promising active materials for the negative electrodes of thin-film batteries. Sodium intercalation into the grain-formed films is a complex electrochemical and mechanical phenomenon, which primarily determines the performance of a battery. Thus, the fundamental understanding of the Na-ions intercalation processes is essential to develop long lasting battery technology.

In the present work we present a phase-field modeling (PFM) study of (electro-)chemical sodiation of SnSb thin-film electrodes. The PFM is developed and applied to explore the sodium diffusion/intercalation and its influence on the evolution of SnSb grain structure. The PFM was developed using the MOOSE Framework.1,2 The model was validated against our experimental measurements, where SnSb thin films are prepared using ball-milling techniques and are deposited onto a carbon film/copper mesh transmission electron microscopy (TEM) grid (EMS CF-400-Cu) using DC magnetron sputtering. In-situTEM and electron diffraction experiments are used to directly image sodium diffusion and to determine the local structures.

Employong the PFM an electrochemical free energy function, considering sodium diffusion within the grains and the grain boundary (GB) along with the elastic stress field associated with Na intercalation, is established. The phase-field GB model is used to generate thin-film grain structures and subsequently to study their evolution under the sodium diffusion. Results show that Na diffusion first proceeds through the GB and then through the grains, and that the electrochemical sodiation is much faster than the chemical sodiation due to an applied electric potential, which drives more Na-ions towards the electrode. The elastic strain energy associated with the sodium intercalation slows down Na diffusion due to the stress build-up. At the first glance, the generated stress has the detrimental effect on the sodiation; however, by slowing down the diffusion process it provides a stabilization function, as less Na is available inside a grain, thus avoiding a potential for irreversible crystallization. In addition, to increase the fundamental understanding of sodium diffusion/intercalation and the GB evolution, sensitivity analysis was performed. Thus, the present modeling work (in conjunction with the experimental work) allows a mechanistic interpretation of the origin of different mechanical, electrochemical and transport phenomena occurring during the sodiation of thin films SnSb electrodes.

References

1. M. R. Tonks, D. Gaston, P. C. Millett, D. Andrs, and P. Talbot, Comput. Mater. Sci., 51, 20–29 (2012).

2. M. R. Tonks, Y. Zhang, A. Butterfield, and X. M. Bai, Model.
Simul. Mater. Sci. Eng., 23, 045009 (2015).
Carbon Nitride-Based Hollow Sphere As Polysulfides-Shuttle Restricting Host for Lithium Sulfur Battery
Authors: Meng Zhen , Ying Hangjun , Han Weiqiang
Published: February 2020

Lithium sulfur battery is a promising candidate to replace the currently lithium ion battery due to the high theoretical specific capacity of sulfur cathode (1675 mA h g−1) and low cost. However, the development of sulfur cathode is hindered by the diffusion of highly soluble polysulfide intermediates formed during cycling and the poor electrical conductivity of sulfur, Li2S2 and Li2S. These issues lead to low Coulombic efficiency, fast capacity fading and low sulfur utilization.

A variety of materials have been employed as sulfur matrixes in attempt to address the above mentioned issues, such as carbon materials, polymers and metal oxides. Recently, graphitic carbon nitride (g-C3N4), which possesses high nitrogen content, has been used as sulfur host. The abundant N atoms in g-C3N4 could retard diffusion of lithium polysulfides into electrolyte via the formation of Li-N chemical interaction between g-C3N4 and lithium polysulfides. However, g-C3N4 could hardly improve the sulfur utilization especially at high current density due to its intrinsically poor electrical conductivity (10−12-10−13 S cm−1). Herein, we successfully designed and synthesized a hollow carbon nitride-based sphere (HCNx) material with enhanced conductivity (10−2-10−3 S cm−1) via polymerization of ethylenediamine and carbon tetrachloride on silica spheres template and used it as sulfur host. The HCNx with nitrogen-enriched structure could not only retard diffusion of lithium polysulfides via the Li–N chemical interaction but also physically confine lithium polysulfides by its hollow structure and mesoporous shells. Furthermore, the enhanced electrical conductivity of HCNx improves the utilization of sulfur. The S/HCNx cathode exhibits a discharge capacity of 579 mAh g−1 after 500 cycles at 0.5C with a fade rate of 0.076% per cycle. When charging and discharging at 2 C, the S/HCNx cathode still exhibits a high reversible discharge capacity of 658 mAh g−1.
(Invited) Advanced Wood Nanostructures Toward Energy-Water Nexus
Authors: Hu Liangbing
Published: February 2020

I will discuss our recent results on multifunctional structures based natural wood materials toward sustainability. I will briefly discuss transparent wood as a replacement of glass for energy efficient building, transparent paper with advanced light management as a replacement of plastics for flexible, biodegradable electronics, and super strong nanopaper as a replacement of steel for automobile and building applications.

I will then focus on wood nanostructures toward energy-water nexus including the following technological areas:

(1) Solar steam generation for water desalination;

(2) 3D wood membrane for waste water filtration (removal of heavy metals and organic waste);

(3) Biodegradable wood-based batteries;

(4) Microbial fuel cells using waster water.

References:

(1) Mesoporous, Three-Dimensional Wood Membrane Decorated with Nanoparticles for Highly Efficient Water Treatment, ACS Nano, 2017, online.

(2) Wood Composite as an Energy Efficient Building Material: Guided Sunlight Transmittance and Effective Thermal Insulation, Advanced Energy Materials, 2016, 6, 1601122.

(3) Transparent and Haze Wood Composites for Highly Efficient Broadband Light Management in Solar Cells, Nano Energy, 26, 3322.

(4) Anisotropic Transparent Wood-Composites, Advanced Materials, 2016, 28, 5181.
(Invited) Overview of NSF-EPRI Collaboratively Funded Advanced Dry Cooling Program
Authors: Shi Jessica
Published: February 2020

US thermoelectric power plants contribute to about 40% of nation’s fresh water withdrawals, primarily due to cooling. While recirculating cooling towers only account for approximately 3% of US fresh water consumption, their water use rates may not be sustainable in some locations. In addition, thermal discharges and water intake for once-through cooling face increasing regulatory scrutiny. Furthermore, siting of new capacity is challenged by water supply constraints. Therefore, breakthrough cooling technology development to minimize fresh water use is emerging as a top priority research topic for all types of thermoelectric plants.

To develop viable game changing solutions, the National Science Foundation (NSF) and Electric Power Research Institute (EPRI) jointly released a $6 M solicitation on advancing dry cooling technologies in 2013. The presentation will highlight several technologies being developed through this collaboration, including alternative dry cooling concepts, such as indirect dry cooling towers with phase-change materials as intermediate coolants, novel heat driven micro emulsion-based adsorption green chillers for steam condensation, on-demand sweating-boosted air cooled heat-pipe condensers for green power plants, direct contact heat exchange and absorption refrigeration based on green non-volatile ionic liquids for enhanced dry cooling of thermoelectric power plants, ejector cooling system with evaporation/condensation compact condenser, and integrated innovative heat pipe dry cooling towers; and enhancement concepts for the currently used air cooled condensers, such as advanced air cooled condensers with vortex-generator arrays between fins, auto flutter enhanced air cooled condensers, nanostructure enhanced air-cooled steam condensers, and porous structures with 3D manifold for ultra-compact air side dry cooling. The progress update and key results will also be provided.
Food Waste to Feed-Stock Chemicals, Using Microbial Consortia and Bio-Hybrid Fuel Cells
Authors: Mackie David Mark , Jahnke Justin P. , Benyamin Marcus S. , LeFors Hannah M. , Sund Christian J.
Published: February 2020

Some microorganisms secrete abundant amounts of diverse enzymes, either naturally or through genetic engineering, that can break down components of food waste (or biomass generally). Simple sugars are thereby produced in solution, where fast-fermenting microorganisms can metabolize them much faster than the secretory microorganisms, producing biofuels. (For example, consortia of the mold Aspergillus oryzae and the yeast Saccharomyces cerevisiae on uncooked rice achieve concentrations of 13% ethanol in 10 days at room temperature.) Secretor-fermenter consortia can be directly coupled with fuel cells (FCs), producing electricity and feedstock chemicals. However, long-term operation of such “bio-hybrid FCs” (BHFCs) requires strictly preventing the microorganisms and FC from harming themselves and each other. This can be accomplished by using gas stripping to continually and selectively extract the (volatile) biofuel from the fermentation medium, and to vapor-feed the FC. This protects the FC from the (non-volatile) catalyst poisons in the fermentation. This also protects the consortium from any harmful FC products (e.g., acetic acid) and from build-up of biofuels, which are inhibitory at high concentrations. We first show that power densities for vapor-fed direct ethanol fuel cells (DEFCs) are comparable to those for liquid-fed DEFCs, with power densities greater than 2 mW/cm2 obtained (orders of magnitude higher than microbial FCs). We then show that mold-yeast-DEFC BHFCs fueled with glucose (or rice) can operate for long periods with no maintenance other than adding water and food. With the right conditions and DEFC, the effluent can be acetic acid at high concentrations and with few impurities. Other effluents from BHFCs are possible, depending on the organisms, food, and FC.
(Invited) The Biotic/Abiotic Interface between Neuromodulation Electrodes and the Peripheral Nervous System
Authors: Wolfson Michael B.
Published: February 2020

This introductory talk will provide background on the anatomy and biological environment of the peripheral nervous system and spinal cord. Building from this foundation, a variety of approaches to build electrical interfaces capable of interacting with tissue will be reviewed. These interfaces typically fall into four major categories: metal alloys, conductive inorganic non-metals, conductive polymers, and capacitive transduction through a dielectric. The requirements for recording neuronal activity are distinct from those for stimulating activity due to the challenges of working in an ionic environment. Information in the nervous system is represented not by the presence of electrons and holes, but by the physical transport of elemental ions within and between cells. By understanding the limitations, constraints, and tradeoffs of current approaches in context of the biological environment, it is possible to envision new opportunities to increase the reliability, safety, and functionality of tissue interfaces.

The remainder of the talk will provide insight into the National Institutes of Health (NIH), its various funding opportunities, and how grant applications are evaluated and funded. Although all federal funding agencies serve the same fundamental purpose, the mission of each is substantially different, which directly shapes its operations and processes. After a “big picture” of NIH funding is presented, a deep dive will be provided on the National Institute of Biomedical Imaging and Bioengineering and the Office of Strategic Coordination’s Common Fund. Several programs within those organizations will be described, including: Advanced Biomaterials, Implantable Medical Devices, and Stimulating Peripheral Activity to Relieve Conditions (SPARC). While the concept of peer review is familiar to all, the NIH implementation of this process has unique nuances that will be described. Finally, suggestions will be provided for investigators on how to best engage with the NIH in pursuit of addressing unmet medical needs.
(Invited) Using Electrochemical Measurements to Diagnose Neural Interface Electrodes
Authors: Troyk Philip , DeMichele Glenn
Published: February 2020

The sophistication of neuroscience experiments designed to elucidate the functionality of the mammalian central and peripheral nervous system is rapidly increasing, and so must the use of more complex electrodes that are used to interrogate the behavior of neural networks. Despite the rapid rise of optical techniques, the metal microelectrode remains the workhorse of experimental neuroscience, and implantable electrode arrays continue to be an important experimental tool. Unfortunately, the reliability of multielectrode arrays remains marginal. While some researchers have been able to record neural activity for many months, or years, more commonly the neuroscientist is hampered by short-term degradation in electrode insulation, increasing array electrical leakage, breakage of wires, and failure of percutaneous connectors. Often these failures obscure the neuroscience experimental goals, and the neuroscientist is left to guess whether changes in data are due to array deficiencies or biological effects.

Initiated by a DARPA grant, our group has developed a microelectrode array analytic and diagnostic instrument that can assess the “health” of implanted electrode arrays. Using a combination of CV, EIS, and pulsed-current measurements, the multiple electrode array analyzer uses 16 parallel potentiostatic modules to perform these measurement modalities in parallel, rather than multiplexing a single instrument. This parallel measurement capability is important because the duration of sessions with experimental animals is often very limited, and the researcher is unable to dedicate a significant portion to merely determining the status of the implanted electrodes. Parallel measurement of 16 electrodes dramatically reduces the time required to diagnose the condition of implanted electrodes at the onset of an experimental session. However, performing parallel measurements of CV and EIS for multiple electrodes pose unique instrumentation challenges that have been addressed in our design.

The performance of this instrument has been evaluated in experiments performed on Macaque with electrode arrays implanted in the brain in a location that is particularly vulnerable to cable breakage. Diagnoses of the electrodes, and connection system, have been performed that clearly show increased electrical leakage as differentiated from biological encapsulation of the electrode tips. The presentation will describe these experiments, the electrochemical data, and the functional diagnoses. 

Our long-term goal is the development and distribution of a diagnostic software module which permits frequent and rapid collection of in-vivo electrode electrochemical data, with the option of upload to a central database for sharing among researchers. Using this diagnostic means, the researcher can anticipate electrode array failures, and make appropriate experimental decisions.
(Invited) New Methods to Fabricate Electrodes for Neurotransmitter Measurements
Authors: Venton B. Jill , Yang Cheng
Published: February 2020

Carbon-fiber microelectrodes have been used for decades for real-time, in vivo measurements of neurotransmitters. However, they require hand fabrication, are difficult to make reproducibly, and have geometries that are limited by the material shape. Our lab is seeking to enhance microelectrode fabrication by designing new strategies for batch fabrication. One strategy is 3D printed molds, that any electrode material (including carbon fibers or CNT yarns) can be laid in and made into an electrode and coated with polyimide. Another strategy is to grow carbon on the inside of quartz nanopipettes to batch fabricate small diameter electrodes. These fabrication strategies, combined with new carbon nanomaterials, will enhance the detection of neurotransmitters in vivo.
Real-Time Bacterial Detection in Liquid By Using Magnetoelastic Biosensors and a Surface-Scanning Coil Detector
Authors: Du Songtao , Liu Yuzhe , Horikawa Shin , Chen I-Hsuan , Chai Yating , Wikle Howard Clyde , Suh Sang-Jin , Chin Bryan A
Published: February 2020

Foodborne illness is a common public health problem because food can be contaminated with pathogens at any point in the farm-to-table continuum. This paper presents a rapid method of detecting foodborne bacteria in a small volume of liquid (1 ml) using magnetoelastic (ME) biosensors and a surface-scanning coil detector. The ME biosensors are mass-sensitive, strip-shaped magnetic particles (1 mm × 0.2 mm × 0.03 mm). Phage was coated on the surface of the biosensors to capture a specific pathogen. The resonant frequency of the biosensors decreases when the specific pathogen is attached to the sensor surface. This decrease in resonant frequency was measured in real time by using a surface-scanning coil detector connected to a network analyzer. In this work, the detection device was comprised of the surface-scanning coil detector and glass capillary tubes with two different diameters (0.5 mm and 0.3 mm). The two capillary tubes were nested each other (i.e., the 3 mm tube inserted into the 5 mm tube) to form a flow channel through which a 1 ml bacteria solution was passed. An ME biosensor was placed inside the flow channel through the 0.5 mm tube and positioned where it meets the tip of the 3 mm tube. The 3 mm tube tip served as a stopper to fix the biosensor position in a liquid stream. The surface-scanning detector was positioned under the biosensor for real-time resonant frequency measurement. The flow channel and surface-scanning detector were embedded and fixed in polydimethylsiloxane (PDMS) to ensure the mechanical stability of the entire device. In order to control and change the flow rate of the bacteria solution, a peristatic pump was used to deliver the solution into the flow channel. The E2 phage was used to specifically capture Salmonella Typhimurium cells in a 1 ml concentrated solution passing through the flow channel. The concentration of Salmonella solutions ranged from 103 cfu/ml to 108 cfu/ml. ME biosensors without E2 phage were used as control sensors, and ones coated with E2 phage were used as measurement sensors. Both groups of sensors were tested by passing the Salmonella solutions, and changes in the resonant frequency of the sensors were recorded. The resonant frequency of the measurement sensors were found to decrease, resulting from specific binding of Salmonella on the biosensors. In addition, the resonant frequency shifts of the measurement sensors were much larger than those of the control sensors for the whole tested range of Salmonella concentrations. The presented method can be combined with surface-sampling of bacterial pathogens by swabbing and used for real-time pathogen detection.
Fabrication of Magnetostrictive Nano-Tubes/Bar As Sensor Plaform
Authors: Zheng ZhiZhi , Cheng Z.-Y. , Zhang Kewei
Published: February 2020

Acoustic wave devices have been used as sensor platforms for the development of biological sensors, in which the surface of the acoustic wave device is coated with a layer of biomolecular recognition unit such as phage and antibody. The sensitivity and many other characteristics of the acoustic wave device based sensors are dependent on the size of the device. The smaller the size of the acoustic wave device is, the higher the sensitivity of the sensor is. Therefore, it is highly interested to fabricate the acoustic wave devices with a smaller size, such as micro/nano-sized devices. It has been experimentally demonstrated that the acoustic wave devices based on the magnetostrictive effect have many advantages over the acoustic wave devices base on effect. For example, the acoustic wave devices based on magnetostrictive effect can be operated wirelessly/remotely, which is very critical, especially for micro/nano-sized acoustic wave devices.

Electrochemical deposition is used to fabricate the magnetostrictive Co-Fe-B alloy in different shapes and sizes. In this presentation, the process to fabricate the nano-sized magnetostrictive Co-Fe-B tubes and bars is reported. The properties of the nano-tubes/bars are characterized and discussed in this presentation. Based on the experimental results, the fabrication process (i.e. the solution concentration, solution temperature, deposition current, and deposition time) is optimized to achieve a high magnetostriction and a quality merit factor.
Rapid Detection of Bacterial Pathogens on 2D Food
Authors: Xi Jianguo , Horikawa Shin , Chen I-Hsuan , Liu Yuzhe , Du Songtao , Lu Xu , Wikle Howard Clyde , Suh Sang-Jin , Chin Bryan A
Published: February 2020

This paper investigates a rapid method of detecting bacterial pathogens on 2D food, such as leafy greens. The method is based on our previous work that uses freestanding phage-coated magnetoelastic (ME) biosensors and a surface-scanning coil detector for direct bacterial detection on the surface of food without commonly used sample preparation steps (washing, concentration, enrichment, etc). The ME biosensors used in this work were ferromagnetic alloy strips coated with E2 phage that specifically binds with Salmonella Typhimurium. First, the biosensors (1 mm × 0.2 mm × 30 µm) were placed in rectangular, indexed cavities (1.1 mm × 0.22 mm × 20 µm) that are etched in a glass wafer. A sheet magnet was added to the back of the wafer to hold the sensors in place. The glass wafer with the biosensors and sheet magnet was then flipped and lowered onto Salmonella-tainted spinach leaves. At this time, a weight was added such that the leaves got flattened to improve the chance for the biosensors to physically contact with Salmonella cells. Various weights ranging from 0 g to 120 g were tested to investigate their effects on the Salmonella binding.

Measurement sensors loaded with E2 phage and control sensors devoid of the phage were prepared and used. The control sensors served as the reference to compensate for the environmental effects such as temperature and humidity. The biosensors were placed on the surface of the spinach leaves for 2 mins for the binding to occur. The degree of the binding of Salmonella to the measurement sensors was determined by measuring the resonant frequency shift of the sensors using a surface-scanning detection system and confirmed by optical microscopy. The binding of Salmonella was found to increase as the spiked Salmonella concentration increased (103 cfu/ml to 108 cfu/ml). In addition, significant resonant frequency shifts of the measurement sensors (4,800 ± 160 Hz) were observed when 60 g of weight was added. However, further increases in weight did not improve the Salmonella binding with E2 phage. Rather, heavier weights increased the probability of non-specific attachment of Salmonella cells and other residuals from the leaf surface.
Detection and Subtyping of Salmonella from Raw Chicken through Targeted Salmonella Capture, Genome Amplification and Whole Genome Sequencing
Authors: Hyeon Ji-Yeon , Li Shaoting , Chin Bryan A , Deng Xiangyu
Published: February 2020

The often low abundance and uneven distribution of bacterial foodborne pathogens in food samples makes rapid, sensitive and specific detection of these pathogens an enduring challenge. Selective concentration of a target organism is often required to bring pathogen cells to a detectable level for subsequent analyses. For example, culture enrichment is still the most widely used method in spite of its lengthy process (i.e., more than 12 hours) that is intrinsically restricted in speed by the length of cell cycle.

Alternative concentration approaches to culture enrichment have been developed. For instance, immunomagnetic separation (IMS) has been applied to certain food matrices. In addition to enriching bacterial cells, amplification of bacterial genomes, for instance, through multiple displacement amplification (MDA), has been shown to facilitate molecular detection of difficult-to-culture pathogens from clinical samples.

We have recently shown that by concatenating IMS, MDA and real-time PCR, we could detect low levels of Salmonella enterica (~10 CFU/g) in raw chicken breast without culture enrichment (Hyeon and Deng, Food Microbiology, 2017)

In this study, we aimed to develop a workflow that consists of 1) specific concentration of Salmonella cells, 2) high-efficiency amplification of bacterial genomes, and 3) molecular detection of Salmonella. The modular design of this workflow allows customized combination of different sample processing and detection methods to meet specific detection need for speed, sensitivity or specificity. In particular, we will demonstrate that the use of a novel magnetoelastic biosensor (Chai et al., Journal of Food Protection, 2012) and whole genome sequencing (WGS) can allow strain-level identification of Salmonella from raw chicken with no or shortened culture enrichment.
(Invited) Spectral Imaging and Instrumentation for Food Safety Evaluation of Agricultural Products
Authors: Kim Moon Sung
Published: February 2020

Researchers at the Beltsville Agricultural Research Center have developed spectral-image-based sensing systems and techniques to reduce food safety risks in post-harvest production and processing. The research objectives focus primarily on comprehensive safety and quality inspection for online bulk processing of fresh fruits and leafy greens, authentication of food ingredients and detection of food contaminants, and improvement of cleaning and sanitation efficacies in food processing facilities. For improved online produce screening, imaging methods and prototype instrumentation have been developed to allow for inspection of whole surfaces of round fruits and relatively flat leafy greens. The prototype produce inspection systems incorporate multi-view and multitask imaging methods for simultaneous reflectance and fluorescence imaging, thus allowing for screening of nearly 100% of the surface areas for fecal contaminants and defects during processing. To detect adulterants, a high throughput line-scan Raman imaging system was developed to rapidly scan large surface areas of food ingredients (e.g., milk powder) for adulterants. In addition, a fluorescence-based handheld imaging technology for contamination detection has been optimized for various commercial applications, such as contamination and sanitation inspection in meat and produce processing facilities. Collectively, these instrumentation and spectral-image-based sensing systems will facilitate rapid, non-destructive detection of contaminants or adulterants in food. The current states of the above spectral imaging and instrumentation technologies are presented.
Photo-Reduced Graphene As Electrode Active Materials for Supercapacitor Applications
Authors: Yang Dongfang
Published: February 2020

Supercapacitors are among the most promising energy storage devices due to their high power density, short recharging time, long cycle life, as well as environmental friendliness. Supercapacitors with increased energy densities are needed for practical applications such as plug-in hybrid electric vehicles, wind turbine energy storage, regenerative breaking, cold starting of trucks and space exploration applications. Supercapacitors store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). Electrochemical double layer capacitors use the high surface area of carbon, such as activated carbon, carbon fiber and graphene, as the electrode active materials, while metal oxides and electronically conducting polymers are used as the electrode active materials for pseudo-capacitors. Graphene is a form of carbon that has substantially higher surface area than the more common electrode active material, activated carbon, and thus potentially allows for more storing of electrostatic charge. The high electrical conductivity and planar structure of graphene also gives rise to fast charging and discharging. In this presentation, recent development on the fabrication of graphene by means of photo reduction of graphene oxide will be given. The photo reduction creates a disordered corrugated graphene structure in which adjacent sheets are no longer oriented parallel to each other. As an example, the performance of excimer laser reduced graphene and N-doped graphene when it is used as electrode active materials in supercapacitors was evaluated in both aqueous and organic electrolytes at room temperature. By varying the laser irradiation processing conditions such as laser energy and irradiation time, graphene and N-doped graphene with different supercapacitive behaviors were successfully grown. The specific capacitance of laser reduced graphene reaches 120 F/g at 5mV/sec in the aqueous electrolyte. Highly conductive N-doped graphene can be prepared by adding NH3 into graphene oxide solution during laser photo-reduction process and the doped graphene has slightly reduced specific capacitance of 110 F/g at 5 mV/sec in 0.5 M K2SO4 aqueous electrolyte. This work demonstrated that excimer laser irradiation process is a very promising technique for preparation of graphene and N-doped graphene for its use as the electrode active material for supercapacitors due to its excellent flexibility and capability of controlling microstructures, electric conduction and specific capacitance.

Figure 1
All-Solid-State Supercapacitor Based on Graphene Oxide Composite Electrodes
Authors: Lo Hsin-Ju , Chen Hsun-Yi
Published: February 2020

Supercapacitors and lithium ion batteries combined are promising hybrid energy storage for portable products, electric vehicles, and smart grid applications. However, the major scientific challenge in this system is to significantly increase the energy density of supercapacitors or raise the power density of lithium ion battery to enhance flexibility for various energy demands.

This study aims to extend the energy density while maintain high specific capacitance through modification of electrodes with graphene oxide (GO) based materials. To prevent leakage of electrolyte, gel polymer electrolyte (GPE) consisting of lithium salt is selected, and it is also able to enhance the mechanical property of the capacitor. GO synthesized by chemical methods from graphite powder is employed because chemically functionalized surface of GO sheet can exhibit derived hydroxyl groups, epoxy groups, and active edges with carboxylic acid groups. Engineering of these functional groups in GO can potentially affect the surface adsorption and in turn improve the performance of capacitors.

In this study, modification of GO surface is conducted and its effects on the all-solid-state supercapacitor are investigated. Characterizations of functionalized graphene oxide have been conducted with x-ray diffraction (XRD), scanning electron microscopy (SEM), and FTIR. Electrochemical performance of these electrodes is investigated using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy.
Low Cost Rapid Synthesis of Exfoliated Graphite Containing Manganese Oxide Materials for Energy and Environmental Applications
Authors: Sykam Nagaraju , G Mohan Rao
Published: February 2020

Carbon materials play considerable role towards energy and environmental applications in a fast growing world. Energy storage and waste water treatment are the two major challenges in the global scenario. Exfoliated graphite, a worm like highly porous carbon nanostructured material exhibits excellent properties and is a potential candidate for many applications. Here, we report rapid and efficient preparation of exfoliated graphite with manganese oxide materials by using microwave irradiation technique, which is one of the most efficient energy sources. The as prepared material was characterized by X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FESEM) and fourier transform infrared spectroscopy (FTIR) techniques. The material showsexcellent electrochemical performance with high specific capacitance value of 166.6 F/g at a current density of 1 A/g under 1M Na2SO4 electrolyte solution. Also, the material shows unusual removal performance of various organic dyes such as congo red (CR) and indigo carmine (IC) from water. The effect of process parameters i.e., pH, contact time, and initial dye concentration on removal of dyes under aqueous solutions was investigated. The adsorption isotherms (Langmuir model), kinetics models (pseudofirst and pseudo-second-order) were used to study the dye adsorption mechanism. It is suggested that the mechanism of adsorption depends mainly on the random distribution of pores, as well as, surface area. The maximum adsorption capacity reaches 222.2 and 204.1 mg/g for IC and CR dyes at equilibrium under aqueous solutions.

Keywords: Carbon materials, porous materials, exfoliated graphite, adsorption, supercapacitors.
Fabrication of Metal Supported Solid Oxide Fuel Cells (MS-SOFC) with Ceria and Zirconia Based Electrolytes
Authors: Toor Sannan Yousaf , Croiset Eric
Published: February 2020

Metal supported solid oxide fuel cells (MS-SOFCs) were fabricated using wet ceramic processing technique. Stainless steel 430 L was characterized for porosity and electrical conductivity to be used as the porous support. D.C. polarization and Archimedes method based on ASTM Standard C373-88 were used for conductivity and porosity measurements respectively. As a benchmark, conductivity of metal support was set to be at least equal to that of anode and the porosity was kept between 35-40%. It was observed that physical properties including shrinkage behavior and CTE are two critical parameters to control during the co-sintering of metal support and electrochemical layers. A combination of inert and reducing atmosphere was also used during sintering of the cell to prohibit any oxidation of stainless steel. Cell characterization was based on scanning electron microscopy (SEM), Electrical Impedance Spectroscopy (EIS) and polarization curves.
Investigation of Fe-Cr-Al Alloy for Metal Supported SOFC
Authors: Pham Hung-Cuong , Taniguchi Shunsuke , Inoue Yuko , Chou Jyh-Tyng , Matsuda Junko , Sasaki Kazunari
Published: February 2020

We are investigating property of Fe-Cr-Al alloy for the application of metal supported solid oxide fuel cell. In general, Fe-Cr-Al alloy showed high oxidation resistance because of its alumina-based oxide layer formed on the surface as a protective layer. We reported previously that the electrical conductivity of the surface oxide layer can be increased by a heat-treatment after coating of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), La0.8Sr0.2MnO3 (LSM), LaNi0.6Fe0.4O3 (LNF), or Pr0.8Sr0.2MnO3 (PrSM). The surface oxide layer on the Fe-Cr-Al alloy after the treatment changed to a microstructure consisting of γ-Al2O3 columns growing outward in the same direction, containing small amounts of elements such as Sr, Fe, La, Ni and Pr. The enhanced electrical conductivity may have resulted from the arrangement of the columnar structure, along with the electronic conduction path generated by the reaction of γ-Al2O3with these elements. Development status of a Fe-Cr-Al based metal supported cell will also be presented.

Acknowledgements

This research is supported by The Japan Science and Technology Agency (JST) through its “Center of Innovation Science and Technology based Radical Innovation and Entrepreneurship Program (COI Program)."
Evaluation of Performance and Degradation Profiles of a Metal Supported Solid Oxide Fuel Cell under Electrolysis Operation
Authors: Nechache Aziz , Han Feng , Semerad Robert , Schiller Guenter , Costa Rémi
Published: February 2020

In this context of energy transition, the use of renewable energies through the conversion of different resources with promising technologies into storable energy carriers is of eminent importance for a sustainable energy supply. Hydrogen production from steam using solid oxide electrolysis cells (SOEC) is part of this so called “energy mix”. Recently, promising progress appeared from the investigation of metal supports in the solid oxide cell architecture. Metal-supported solid oxide fuel cells (MS-SOFCs) show not only good mechanical strength, relatively low operating temperature (500-750 °C) and improved sealing capability but also low materials cost and tolerance towards rapid thermal cycling and redox cycling [1-3]. In the present study, a MS-SOFC was tested under electrolysis conditions. The cell consisted of Ni-catalyst-loaded La0.1Sr0.9TiO3-α/gadolinium-doped ceria (Ni-LST/GDC) as fuel electrode, gadolinium-doped ceria/yttrium-stabilized zirconia (GDC/YSZ) as electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) as O2 electrode. After a short testing period in fuel cell mode, a first evaluation of the cell performance profile in electrolysis mode was performed. Thus, a series of current-voltage curves as well as impedance diagrams (under OCV and under load) was recorded for different fuel electrode gas compositions. Furthermore, degradation under electrolysis operation was also investigated based on the evolution of the cell voltage against time for several currents applied. Consequently, analysis of the post-mortem characterization by SEM/EDX, along with the electrochemical testing results, aims at identifying the changes in cell characteristics specifically related to degradation under electrolysis operating conditions.

[1] M. C. Tucker, J. Power Sources 195 (2010) 4570-4582.

[2] J. T.S. Irvine, J. Bae, J-Y Park, W. S. Choi, J. H. Kim, Int. J. Hydrogen Energy, In Press-Corrected Proof.

[3] A. M. Dayaghi, K. J. Kim, S. Kim, J. Park, S. J. Kim, B. H. Park, G. M. Choi, J. Power Sources 324 (2016) 288-293.
Co-Electrolysis with CFY-Stacks
Authors: Megel Stefan , Dosch Christian , Rothe Stefan , Folgner Christoph , Trofimenko Nikolai , Rost Axel , Kusnezoff Mihails , Reichelt Erik , Jahn Matthias , Michaelis Alexander , Bienert Christian , Brandner Marco
Published: February 2020

The efficient high temperature electrolysis is of high interest for potential application in a renewable energy system. The possibility to use high temperature heat for the electrolysis reaction makes the SOEC technology an attractive option for the integration in process concepts for the production of valuable chemicals from renewable energies. Moreover, the SOEC allows the electrolysis of water and carbon dioxide in a so-called Co-electrolysis. The produced syngas can be used in a subsequent synthesis step, e.g. a Fischer-Tropsch synthesis. The development of these power-to-product processes as well as of necessary components are in focus of current research activities at IKTS. The main component is the high temperature electrolyzer (SOEC). In collaboration with Plansee SE, the CFY stack technology has been developed. This stack technology can be applied for SOFC, SOEC and reversible operation (rSOC) and establishes an universal platform for different applications.

Performance maps of a MK352 CFY stack in steam- (H2O) and Co- (H2O/CO2) electrolysis operation show a difference in electric power demand of less than 5 %. This low additional power demand of Co-electrolysis together with the advantages of direct syngas production makes it promising for highly efficient integration within a process concept for the production of valuable hydrocarbons. The output syngas can be directly adjusted by choosing appropriate operating conditions for the SOEC to typical compositions used for reactions like Fischer-Tropsch synthesis. Based on this approach the operating conditions were set and durability tests with stacks (>1500 h) were conducted. The results raised several scientific questions which were answered by splitting the “black box” of the stack in separate parallel investigated experiments in the fields of cell tests, tests of interconnect materials, contact resistances, protective layer and glasses.

The surprising behavior of reversible degradation of the stacks was analyzed by single cell experiments and could be reduced by adjusting of operating conditions and resulted in a fine tuning of the electrode design. Nevertheless still an irreversible degradation of about 1%/1000 h was detected. Several material tests consolidated the common understanding of degradation phenomena and will be shown with comparison to the real stack tests. The results show the excellent suitability of the CFY stack for electrolysis applications and give an outlook on further improvements.

Figure: 30-cell MK352 stack for SOFC/SOEC and rSOC operation

Figure 1
Electrochemical Upgrading of Bio-Oil
Authors: Elangovan S , Larsen Dennis , Bay Insoo , Mitchell Evan , Hartvigsen Joseph , Millett Byron , Elwell Jessica , Santosa Daniel , Elliott Douglas C
Published: February 2020

Bio-oil produced by fast pyrolysis of biomass is a potential source of low carbon, renewable hydrocarbon fuel. However, the properties such as low heating value, incomplete volatility, acidity, instability, and incompatibility with standard petroleum fuels significantly restrict its use as fuel. The undesirable properties of pyrolysis oil result from its chemical composition that mostly consists of different classes of oxygenated organic compounds. The elimination of oxygen is thus necessary to transform bio-oil into a liquid fuel that would be broadly accepted and economically attractive. Hydrodeoxygenation (HDO) or hydrotreating involves high-temperature, high-pressure processing in the presence of hydrogen and catalyst to remove oxygen. HDO suffers from significant challenges such as coking, deactivation of HDO catalysts by the presence of water in the pyrolysis oil, requirement of significant quantities of hydrogen to remove oxygen, and economic availability of hydrogen at a scale suitable for distributed biomass conversion. An alternative economically feasible, less hydrogen dependent and decentralized process is required to convert bio-oil to refinery ready hydrocarbons.

A process of deoxygenation of bio-oil using solid-state, oxygen conductor based electrochemical cell is under investigation. The cell is operated at 500 – 550 °C to match the typical pyrolysis temperature for both physical and process integration of the two operations. The electrolysis process removes oxygen from the oxygenated organic molecule as well from steam to produce hydrogen in-situ. Thus, relatively small quantities of external hydrogen may be needed for deoxygenation, allowing for a distributed, small scale integrated upgrading unit. Mixtures of model compounds were tested using button cells and short stacks. The product from the electrochemical cell contained a suite of compounds with significantly lower oxygen content. Integrated testing of short stacks at the Pacific Northwest National Laboratory using a slip stream from a pyrolyzer shows that the product composition is similar to catalytic pyrolysis process. Additional tests are planned using improved electrode materials.

Acknowledgment: This material is based upon work supported by the Department of Energy under Award Number DE-EE0006288.
New Design Concept of Ni‒Doped-Ceria Cermet Anode for Solid Oxide Fuel Cells: Redox-Induced Self-Modification
Authors: Matsui Toshiaki , Eguchi Kohei , Shirai Keisuke , Okanishi Takeou , Muroyama Hiroki , Eguchi Koichi
Published: February 2020

Solid oxide fuel cells (SOFCs) are promising energy conversion systems for the next generation. High-temperature operation of this electrochemical device offers high fuel flexibility as well as high energy conversion efficiency. Currently, methane is widely utilized as the main fuel source for the residential SOFC cogeneration system, and the pre-reformed gas is supplied to the anode chamber. In this case, the anode is requested to be active for the reforming reaction of hydrocarbons as well as the electrochemical oxidation of fuels. The tolerance to carbon deposition is also an important property to provide against accidents of the reforming system because the hydrocarbon will be directly introduced to the anode.

Recently, Kubota has reported the strong chemical interaction between Ni and GDC (Gd2O3‒CeO2) for the Ni‒GDC cermet anode in solid oxide fuel cells [1]; CeO2 species migrated on the Ni surface after the exposure to the reducing atmosphere. Generally, such a chemical interaction is promoted by the redox treatment. In this study, then, the influence of redox treatment on the chemical interaction between Ni and doped ceria was studied to design the cermet anode with high tolerance to carbon deposition.

The Ni‒GDC cermet subjected to the redox treatment showed high tolerance to carbon deposition in dry methane. Furthermore, the redox treatment did not affect the mechanism of electrochemical hydrogen oxidation in wet hydrogen atmospheres. We also demonstrated the stable power generation of the single cell with the optimized Ni‒GDC anode in a wet methane atmosphere.

Acknowledgements

This study was supported by Japan Science and Technology Agency (JST), CREST.

Reference [1] J. Kubota, The 23th Symposium on Solid Oxide Fuel Cells in Japan, Extended Abstract, p34-37 (2014).