bluuebunny/crossref_metadata_2025 huggingface dataset:
Digital Communication through Solids Using Magnetostriction
Authors: Faltas Mina , Pillars Jamin R. , Elkady Ihab
Published: September 2023

Digital communication through solid materials such as metals, ceramics, organic solids, or semiconductors has many applications. Only communication through metals has been attempted via ultrasonic waves. However, its performance is significantly hindered by echo interference. A way to enable communication through these solids is by the exploitation of magnetostriction. Magnetostriction is a property where a magnetic material changes its shape during the process of magnetization, essentially converting magnetic energy into kinetic energy. The kinetic energy produced by the magnetic material can then be taken through the solid media through which communication is intended to occur. The kinetic signal on the other side of the solid media could be converted to whatever type of energy is suitable for the application.

This energy transduction channel, using magnetic energy and kinetic energy, can optimally be achieved through a soft magnetic material with high magnetostriction. A nickel-iron-cobalt based alloy was used to develop a material with a saturation magnetostriction over 200ppm, that can be electrodeposited out of an acidic aqueous chemistry. Initial high intrinsic stress in the deposited alloy was controlled with additives and altering the complexing, enabling consistent deposits of over a millimeter in thickness.

The electrodeposited material’s performance is characterized and correlated to material properties such as alloy composition, microstructure, grain size, coercivity, magnetic saturation, Young’s Modulus, etc. The characterization methods used to analyze the magnetostrictive material and the effect of modulating plating parameters to control material properties will be presented. Additionally, the effect of annealing the material in an inert environment at varying temperatures and dwell times will be examined.

Sandia National Laboratories is a multimission laboratory managed and operated by National
Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell
International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration
under contract DE-NA0003525.

This paper describes objective technical results and analysis. Any subjective views or opinions
that might be expressed in the paper do not necessarily represent the views of the U.S.
Department of Energy or the United States Government.
SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525
High Throughput Plastic Sorting Technique Based on Molecular Vibrational Signatures
Authors: Chakraborty Patatri , Zhao Yaoli , Goyal Amit , Thundat Thomas
Published: September 2023

Plastic pollution is an enormous environmental problem that has been increasing exponentially in the last few decades. Despite the huge public awareness, overall recycling rate remains only at 8.7%. Overall recycling of post-consumer plastic can be recovered only with improved separation efficiency at the Material Recovery Facilities (MRF). Therefore, the success of plastic recycling critically depends on developing cost-effective techniques that automate the entire process of sorting plastics based on their chemical composition in a high throughput fashion. At present, the most effective methods like NIR, LIBS Raman spectroscopy or AI robotic arms have poor sensitivity, subpar selectivity, increased risk of false identification and inability to detect black plastics. Here we report a novel, simple and cost-effective technique that can increase the sensitivity, molecular selectivity, and speed of plastic sorting. This approach relies on resonant excitation of molecular bonds with pulses of mid-infrared radiation that are unique to the selected resin. Non-radiative relaxation of resonantly excitation of vibrational states increases the local temperature of the irradiated area. The increased local temperature is then imaged with a highly sensitive infrared camera. Superimposition of the thermal and visible images provide identification each plastic enables high throughput sorting. This technique has the potential to sort black plastics rapidly, which is a major challenge for any other currently used technique.
Electrochemical Biosensors for Clinical Analysis
Authors: Soleymani Leyla , Li Yingfu
Published: September 2023

In this talk, we will discuss the marriage of nucleic acids with electrochemical biosensors for the development of rapid clinical tests. These tests integrate both functional nucleic acids (aptamers and DNAzymes) and antibody/DNA complexes for developing barcode-based electrochemical biosensors. The barcode is a DNA strand modified with an electrochemical label that can be detected using an electrochemical chip. Following the presentation of different DNA barcoding methods, we will also present strategies for operating these biosensors in blood, saliva, and urine for direct analysis of clinical samples for the diagnosis of infectious diseases and cancer without the need for target enrichment methods such as growth cultures or nucleic acid amplification. These devices demonstrate the potential for rapid clinical testing at the point-of-need.
NO Gas Sensor Based on Ti-Doped ZnO Thin Films Prepared by SILAR Method
Authors: Soltabayev Baktiyar , Yergaliuly Gani , Ajjaq Ahmad , Acar Selim , Bakenov Zhumabay , Mentbayeva Almagul
Published: September 2023

In this study, Ti-doped ZnO films with flower-rod-like nanostructures were synthesized by the SILAR method for enhanced NO gas sensing applications. The stoichiometric ratio of Ti in the host ZnO lattice was confirmed by atomic absorption and energy-dispersive X-ray spectroscopies. All the synthesized films exhibited a pure wurtzite hexagonal structure that seemed to deteriorate at high Ti doping contents as it was manifested by the measured X-ray diffraction patterns. Scanning electron microscopy images of ZnO revealed the coexistence of porous flower- and rod-like structures, and became finer, denser and more compact with Ti doping. By UV-Vis measurements, the transmittance of the synthesized pure ZnO thin film in the visible region (~75%) increased by about 10% with Ti doping, and the energy bandgap seemed to decrease up to a some limit of Ti content. Among the fabricated sensors (based on pure ZnO, 1% Ti-doped, 3% Ti-doped and 5% Ti-doped ZnO films), the best sensing performance was observed for the 1% Ti-doped ZnO film. At first, this was associated with its high density of oxygen vacancies present on the surface of the film and ionized oxygen vacancies present in the ZnO lattice (confirmed respectively by X-ray photoelectron and photoluminescence spectroscopies). Nonetheless, this may be also due to its increased crystallinity (confirmed by X-ray diffraction and photoluminescence spectroscopy), high area-to-volume ratio (confirmed by scanning electron microscopy images), high specific surface area (confirmed by Brunauer-Emmett-Teller measurements) as well as high mobility and carrier concentration (confirmed by Hall measurements). The sensor was highly selective to NO gas and showed notable stability as well as very short response and recovery times which makes it eligible for the early detection of any indoor or outdoor NO gas leakages.

Keywords
: SILAR, Ti-doped ZnO, Structural properties, Optical properties, Electrical properties, Gas sensor.

Acknowledgement

This research was supported by the research grant 021220FD2201 “Development of highly sensitive MOS based nano-film gas sensors” from Nazarbayev University.

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Approaches for Optimum Thermal Management of SOFC Cells: Fitting Operating Conditions & Smart Cell Design
Authors: Judez Xabier , Jimenez-Martín Gonzalo , Aguado Mónica , Garbayo Iñigo
Published: September 2023

The thrust of green hydrogen as energy vector for the consolidation of a net-zero emitting global energy system implies the necessity of a fast development of high performing and highly efficient fuel cells and electrolyzers. Among the commercial choices, solid oxide cells can be considered as a better performing alternative compared to commercial proton exchange membrane and alkaline technologies. The benefits of this kind of technology arise from their higher operating temperatures of around 700-900 ºC, which results in improved kinetics and favored thermodynamics, allowing to reach unrivaled conversion efficiencies and reduced electricity consumption. Furthermore, this allows operating the cell reversibly in both fuel cell (SOFC) and electrolysis (SOE) modes.

However, cell overheating and non-uniform temperature distribution can lead to an acceleration of degradation processes and cell cracking and sintering, which challenges long-term cell stability. In this sense, modeling at cell level enables to optimize operating conditions, improve cell design and predict and minimize such phenomena. Simulations allow mimicking the response of the cells and stacks at diverse operating scenarios and accelerates the optimization process minimizing experimental efforts; saving materials, time, and economical resources. We model SOFC/SOE cell behavior by means of Computational Fluid Dynamics (CFD), solving the mass, species, momentum, energy and current conservation equations, as well as electrochemical reaction models.

In this work, a detailed methodology to guide design of the thermal management of SOFC by means of CFD and numerical optimization tools is proposed. These approaches combine acting both on operating conditions and cell geometry. Initially, we study the influence of inlet gas flows and describe a procedure to optimize the flows while maximizing the energetic outcome. Afterwards, we describe how numerical methods can allow fitting feed gas temperatures to avoid overheating. Finally, we go a step further by optimizing cell interconnect plate geometries to minimize internal temperature gradients. All in all, we demonstrate how CFD studies can accelerate SOFC cell design in order to maximize performance and extend lifespan.

Figure 1
Nanostructured LSC Thin Film Electrodes with Improved Electrochemical Performance and Long-Term Stability
Authors: Bagarinao Katherine Develos , Celikbilek Ozden , Kerherve Gwilherm , Fearn Sarah , Skinner Stephen J , Kishimoto Haruo
Published: September 2023

Nanostructured La0.6Sr0.4CoO3-δ (LSC) thin film electrodes exhibit exceptionally high oxygen surface exchange properties, surpassing those of conventional microscale electrode structures, which are desirable for application in solid oxide cells (SOC) [1-2]. On the other hand, the LSC nanostructures also tend to undergo significant morphological changes at typically high temperatures required for SOC operation, leading to rapid degradation in performance. Here, towards the goal of improving the long-term stability of electrochemical performance of nanostructured LSC thin films, a systematic investigation of the effect of processing temperatures on long-term stability was carried out [3]. By varying the deposition temperature (500 °C to room temperature), the as-grown characteristic nanostructures of LSC thin films prepared using pulsed laser deposition can be tuned from highly dense nanocolumnar grains to nanofibrous structures with high porosity. Variations in the deposition temperature also resulted to differences in the proportion of surface-bound/lattice-bound Sr and Co2+/Co3+ at the surfaces of the as-grown LSC thin films; however, prolonged annealing at 700 °C in air essentially transforms the surfaces to a final state with mostly lattice-bound Sr and Co3+. Nevertheless, LSC films with initially nanofibrous structures are found to be less prone to the grain sintering effect occurring at high temperatures and exhibit less degradation of the electrode polarization resistance as compared to well-dense films. Using lower deposition temperatures, cation interdiffusion occurring at LSC/GDC interfaces is also significantly suppressed, thus leading to better interfacial stability as compared to those prepared at higher deposition temperatures. These results highlight the relationship between characteristic nanostructures of thin film electrodes and electrochemical performance and provide guidance on designing electrodes with improved long-term stability.

[1] J. Januschewsky, M. Ahrens, A. Opitz, F. Kubel and J. Fleig, Adv. Funct. Mater., 2009, 19, 3151–3156.

[2] J. Hayd, L. Dieterle, U. Guntow, D. Gerthsen and E. Ivers-Tiffee, J. Power Sources, 2011, 196, 7263–7270.

[3] K. Develos-Bagarinao, O. Celikbilek, R. A. Budiman, G. Kerherve, S. Fearn, S. J. Skinner and H. Kishimoto, J. Mater. Chem. A, 10, 2445-2459 (2022).
Numerical Modeling for LSCF Electrodes with Nanocatalyst Infiltration
Authors: Yang Tao , Guan Bo , Liu Jian , Fan Yueying , Finklea Harry , Abernathy Harry W. , Epting William K. , Kalapos Thomas , Hackett Gregory A.
Published: September 2023

As a mixed ionic-electronic conducting (MIEC) material, lanthanum strontium cobalt ferrite (LSCF) is widely used for solid oxide cells (SOCs) in both fuel cell mode and electrolysis mode. The performance and stability of LSCF electrodes can be further enhanced by nanocatalyst infiltration. In this study, a numerical model is developed to investigate the performance of LSCF electrodes modified with infiltrated nanocatalysts. The multiphysics model describes the chemical/electrochemical reactions, charge conservation, and species transport within a SOC button cell. The electrochemical reactions are represented by Butler-Volmer type expressions which couples the physical processes of the cell. The microstructural properties are estimated from experimental imaging to improve the accuracy of the study. The changes of microstructural properties and reaction mechanisms due to nanocatalyst infiltration are also implemented to investigate the effects of infiltrated lanthanum strontium cobaltate (LSC) nanoparticles. The numerical model is first calibrated by adjusting model parameters for good agreement between simulated performance and experimental datasets for a referenced cell. Then the calibrated model is utilized to predict the polarization curves and impedance behavior for backbones with different grain sizes and composition volume fractions. The simulated results for both baseline backbones and infiltrated backbones are also thoroughly analyzed to extract the changes of different physical processes due to the nanocatalyst infiltration. The comparison of performance changes among the backbones under this study provides guidance about the optimum backbone for nanoparticle infiltration technology.
Performance Evaluation of an Anode-Supported Solid Oxide Fuel Cell Short-Stack Operating with Different Hydrogen-Natural Gas Blends as Stationary Combined Heat and Power System
Authors: Monforti Ferrario Andrea , Santoni Francesca , Marino Francesco , Alfano Antonio , Stenius Julius , Noponen Matti , Neubauer Raphael , Cigolotti Viviana
Published: September 2023

One of the most promising characteristics of Solid Oxide Fuel Cells (SOFCs) is the possibility to process a wide variety of fuels with high electrical efficiencies, when compared to other types of fuel cells. Considering the prospected transition of the Natural Gas (NG) grid to hydrogen to decarbonize the gas sector, SOFCs could play a crucial role as efficient and clean stationary Combined Heat and Power (CHP) systems.

In this work a 15-cell SOFC short-stack (Anode Supported, cell area 121 cm2) has been analysed experimentally under different compositions resembling possible short-, medium- and long-term gas grid scenarios (100% NG, 67%H2 blend in NG and 100%H2) which have been obtained by a preliminary system-level simulation which takes into account operating conditions of the stack and fine-tuning of the system parameters (e.g. Recirculation Rate RR, once through Fuel Utilization FUot, global Fuel Utilization FUtot) to optimize the overall system-level efficiency. Several tests were run at different temperatures (640-710 °C), Fuel Utilization (FU, 50%-70%) and at current loading (15-30 A - part/full load), characterizing in detail the stack response from an electrochemical (polarization curves and short-term stability tests) and chemical conversion point of view (gas chromatographic analyses in OCV and under load), as well as mapping its performances in stationary conditions (output power and stack-level efficiency). The conversion efficiency has been assessed in detail with different approaches at both stack and cell level, considering both once-through (stack-level) and total (system) FU rates.

After having confirmed that the stack performances in reference testing conditions are fully aligned to the stack manufacturer data, confirming the test bench setup validity, the foreseen testing campaign has been carried out showing compatibility of the SOFC stack in the investigated conditions. The results show that from a pure performance point of view the 100%H2 composition obtains highest voltage and power at nominal conditions due to losses of the reformate compositions due to lower OCV values and kinetic behaviour of the chemical reaction chains. Instead, from an efficiency point of view the reformate conditions obtain higher stack-level efficiency (72.02% for the 67%H2+NG; 69.45% for the 100%NG) respect to the 100%H2 compositions (68.61%) due to the lower input fuel calorific value. The comparison of the different efficiency definitions provides further insight on the process and system level. By comparing reference testing conditions before and after the testing campaign it is possible to confirm that no significant degradation has occurred at global stack level in all the compositions.

Figure 1
Ion Beam as an External and Dynamic Metal Reservoir to Induce Nanoparticle Exsolution in Oxides
Authors: Wang Jiayue , Woller Kevin B. , Yildiz Bilge
Published: September 2023

A central theme in solid oxide fuel cells (SOFC) and electrolyzers (SOEC) is to design stable and catalytically active solid/gas interfaces toward desired reactions. A recent advance in this regard is to synthesize nanoparticles decorated electrodes in a process termed “exsolution”. Exsolution generates stable and catalytically active metal nanoparticles via phase precipitation out of a host oxide. Unlike traditional nanoparticle infiltration techniques, the nanoparticle catalysts from exsolution are anchored in the parent oxide. This strong metal-oxide interaction makes the exsolved nanoparticles more resistant against particle agglomeration as compared to the infiltrated ones. In addition, the exsolved particles also open up the possibility of regeneration of catalysts. To date, the concept of exsolution has been successfully applied to a number of applications including SOFC/SOEC, ceramic membrane reactors, chemical looping combustion, and (electro)catalysis.

As the exsolution process starts with a solid-solution that contains the to-be-exsolved transition metal ions, this method is often limited by the intrinsic solubility limit of the host oxide. Here, we propose that ion beam irradiation to be a unique tool to promote exsolution as it can introduce defects and dopants into the host oxides and at concentrations higher than thermodynamic limits. Moreover, due to the surface sputtering effect, ion beam irradiation can modulate the surface morphology, creating novel nanostructures.

To demonstrate this approach, we chose thin-film perovskite SrTi0.65Fe0.35O3 (STF) and fluorite Ce0.5Zr0.5O2 (CZO) as model systems, both of which are promising materials in SOFC and SOEC. We modulated metal exsolution in both materials with in-situ 10-150 keV Ni irradiation at 800 °C in vacuum. Ni irradiation on STF controllably changed the exsolved particle composition from unitary Fe to bimetallic Fe-Ni. Moreover, it also reduced the particle size down to sub-2 nm, which outperforms other tuning methods thus far in the literature. As a result, the irradiation-modified STF demonstrated superior catalytic activity toward room-temperature oxygen evolution reactions (OER) than the conventional thermally exsolved STF. Regarding CZO, Ni irradiation also decorated the surface with well-dispersed nanoparticles, leading to enhanced high-temperature H2O splitting kinetics. The effective size and composition control over exsolution highlights the utility of metal ion beams in promoting and tailoring exsolved nanocatalysts for a broad range of applications in clean energy and fuel conversion.

Figure 1
Ceria-Nickel Fuel Electrode for Reversible and Fuel Flexible Operation: Scaling-up from Electrolyte- to Electrode-Supported Cell
Authors: Sarruf Bernardo , Steinberger-Wilckens Robert
Published: September 2023

Solid oxide cells are devices that figure great versatility of fuels whilst in fuel cell mode like biogas, bioalcohols, or hydrogen with no need of high purification, and are also reversible, meaning that the same equipment can operate as an electrolyser being thus capable of converting water/steam or carbon dioxide into fuel for strategic reserve purposes. The FleXelL project, aims to develop a fuel electrode material based on nickel, cerium oxide and yttria-stabilised zirconia to accommodate such virtues – flexibility and reversibility. The physical assessment of the materials was done via X-ray diffraction analysis, which confirmed the phases integrity, and dilatometry outputs that allowed the fabrication of the fuel electrode and electrolyte layers by the tape casting technique with minimum thermal mismatches. The gadolinium-doped ceria protective layer and the lanthanum-strontium cobalt ferrite oxygen electrode were both deposited by spin coating. After the successful manufacturing, the cells were tested electrochemical by polarisation both in fuel cell mode whilst hydrogen or anhydrous methane served as fuels reaching peak power densities as high as 0.7 W.cm-2, or under electrolysis mode achieving current densities above 2 A.cm-2 with a voltage of 1.25 V. The high efficiencies of the cells specially under electrolysis is attributed to the ability of ceria to act as an oxygen buffer, which avoided the deactivation/oxidation of the nickel catalyst under high electrical currents. After operation, the microstructure was investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy to confirm the suitability of the microstructure even after the harsh operation.
Experimental Study on High-Efficiency Microtubular Solid Oxide Fuel Cell Stacks Using Various Fuels
Authors: Shi Jixin , Yao Yue , Zhang Ruiyu , Wang Yuqing , Fan Junhua , Shi Yixiang , Liang Bo , Cai Ningsheng
Published: September 2023

Abstract: Microtubular solid oxide fuel cells (mtSOFCs) are a clean and low carbon emission power generation technology that has great prospects in the field of portable power generation. Improving the power generating efficiency and broadening the variety of fuels available can significantly improve the performance of portable power generation devices based on mtSOFCs. In this study, mtSOFC stacks assembled by mounting modular substacks in an array on a designed fuel/air distribution base were tested. By changing the connection of the substacks’ current collection nodes, the influence of circuit connection modes on the overall output performance of the stack was studied. At a temperature of 700℃ and a fuel feed of hydrogen, the mtSOFC stack composed of 6 substacks in series can achieve a maximum power of 296 W. Fuel cascade utilization was realized by transferring the spent fuel gas from the upstream substacks to the downstream substacks. A maximum power generation efficiency of 45.7% was achieved in the two-cascade stack. The feasibility of using liquified fuel gas (ammonia, propane and diesel) as fuel for the mtSOFC stack has also been experimentally verified. A total continuous discharge time of more than 100 h was achieved at an average power ≥ 180 W under different fuel conditions.

Key words: Microtubular SOFC; Substack array; Fuel cascade utilization; Liquified fuel gas; Ammonia
Modeling the Distribution of Oxygen Partial Pressure in the Electrolyte of Solid Oxide Cells and Its Implication on Microstructure Evolution in the Hydrogen Electrode
Authors: Lei Yinkai , Cheng Tianle , Yang Tao , Epting William K. , Abernathy Harry W. , Wen You-Hai
Published: September 2023

The distribution of oxygen partial pressure in the electrolyte has an important effect on the stability of solid oxide cells (SOCs). It is well known that the high oxygen partial pressure at the oxygen electrode and electrolyte interface causes delamination, while its effect in the hydrogen electrode (HE) has received comparatively little attention. The only existing model for the distribution of oxygen partial pressure in the electrolyte of SOC is proposed by Virkar et al., which is a one-dimensional model that does not consider the Butler-Volmer equation at triple phase boundary (TPB) nor the microstructure’s effect. In this work, the Virkar’s model was extended to three dimensions and the Butler-Volmer equation was added at TPB to investigate the distribution of oxygen partial pressure in the actual electrode microstructure. The oxygen partial pressure in the YSZ phase of HE near the HE-electrolyte interface was found to be significantly greater than the oxygen partial pressure in the pore phase of HE, which may lead to Ni oxidation. Furthermore, a phase field model was employed to simulate the microstructural evolution of Ni particles on YSZ surfaces with the assumption that NiO forms at the Ni-YSZ interface. The NiO formation affects the microstructure evolution in HE by changing the shape of the Ni particles.
Reverse Water Gas Shift Versus Carbon Dioxide Electro-Reduction: The Reaction Pathway Responsible for Carbon Monoxide Production in Solid Oxide Co-Electrolysis Cells
Authors: Nielsen Anders Stanley , Peppley Brant , Burheim Odne
Published: September 2023

Solid oxide co-electrolysis cells are an emerging technology that can utilize renewable energy sources for the conversion of steam and carbon dioxide into valuable chemicals and feedstocks. An important challenge in the analysis of these devices is understanding the reaction pathway(s) responsible for the production of carbon monoxide. Some researchers have suggested that it is largely attributed to the reverse water gas shift reaction, since the polarization curves of pure steam electrolysis and co-electrolysis overlap each other; therefore, they surmised the electro-reduction of carbon dioxide is inconsequential to carbon monoxide production. Conversely, other studies have shown the polarization curves corresponding to co-electrolysis lie between those of pure steam and pure carbon dioxide electrolysis, thus indicating the reverse water gas shift reaction and the electro-reduction of carbon dioxide are both contributors. For the first time, this analysis attempts to untangle the conflicting phenomena observed in previous experiments by utilizing dimensional analysis, thermodynamics, and reaction kinetics. We illustrate the operating regime in which both reaction pathways contribute to the production of carbon monoxide, while demonstrating that the reverse water gas shift reaction is inconsequential when steam electrolysis and co-electrolysis polarization curves coincide, which is contrary to what has been concluded in previous analyses. This work is intended to provide an enhanced understanding of the observed behaviour of solid oxide co-electrolysis cells, and can help designers and researchers make informed decisions on how to construct their cell to exploit a desired reaction pathway.
Current Status of Ceres Electrolysis Programme
Authors: Hjalmarsson Per , Harman Jonathan , Macauley Chandra , Methley Ian , Ryley Joshua , Zerfa Amin , Hargrove Caroline , Selby Mark
Published: September 2023

This report provides an update on Ceres SOEC programme. Since its start Ceres’ state of art technology has been evaluated in electrolysis mode, both experimentally and using modeling at cell, stack, and system level, in parallel to developing its first 1 MW scale demonstrator system.

Electrochemical performance, measured at cell level, shows similar performance in EC and FC mode within nominal operating conditions. Durability of stack repeat units has been measured experimentally at a range of different conditions. The degradation rate during the initial ~5000 hrs was found to range from 15-25 mΩcm2/khrs with a decaying trend over time. Degradation behaviour has been correlated with boundary conditions to provide a tool for optimizing and predicting life.

A stack Multiphysics model has been developed that considers the electrochemical reactions as well as transfer of heat, fluids, and charge. The model was validated against stack test data with very good correlation and is being used for predictive analysis of stack performance under relevant conditions. The results show that Ceres stack will work equally effective in electrolysis mode as it does in fuel cell mode.

Finally, performance of SOEL systems incorporating Ceres electrolyser stacks have been evaluated by system modelling at different boundary conditions. This allows us to assess system efficiency and levelized cost of hydrogen for different scenarios and sets of assumptions.
Influence of Microstructure on the Sulfur Tolerance of Ceria-Based Anodes in Low Temperature SOFC
Authors: Kullmann Felix , Schwiers Alexander , Juckel Martin , Menzler Norbert H. , Weber Andre
Published: September 2023

Hydrocarbon fuels such as natural gas, propane or biogas commonly contain small amounts of impurities like sulfur which result in a strong degradation of the cell performance in the intensively studied Ni/YSZ cermet anode [1-3]. The sulfur poisons the nickel catalyst and hinders the electrooxidation of hydrogen [2-3].

At common SOFC operation temperatures of 700 to 900 °C the polarization resistance of a Ni/CGO fuel electrode is less influenced by sulfur [3-5]. With a modification of the surface by infiltration of Ni and / or ceria nanoparticles the impact can be even reduced [5-6]. The trend to a much lower operating temperature of SOFCs [7-8] even below 600 °C raises the question to what extend the sulfur tolerance of ceria-based fuel electrodes is maintained.

In this study we analyze the impact of H2S on the polarization resistance of ceria-based fuel electrodes at operation temperatures around 600 °C. Ni/ceria anodes, differing in their microstructure, are investigated by electrochemical impedance spectroscopy (EIS). The distribution of relaxation times (DRT) analysis is applied to deconvolute the electrochemical processes followed by a complex nonlinear least square approximation to quantify the loss processes and the impact of sulfur amounts of 0.1-3 ppm. Compared to previous results [5] the polarization resistance increases more significantly at 600 °C than at 750 °C. The influence of the microstructure will be discussed in detail.

References:

[1] A. Weber, Fuel Cells, 21, 440 (2021).

[2] A. Kromp, S. Dierickx, A. Leonide, A. Weber and E. Ivers-Tiffée, J. Electrochem. Soc., 159, B597 (2012).

[3] A. Weber, S. Dierickx, N. Russner and E. Ivers-Tiffée, ECS Trans., 77, 141 (2017).

[4] M. Riegraf, M.P. Hoerlein, R. Costa, G. Schiller and K.A. Friedrich, ACS Catal., 7, 7760 (2017).

[5] A. Weber, T. Dickel and E. Ivers-Tiffée, in Proceedings of the 12th European SOFC & SOE Forum, B0507 (2016).

[6] T. Hays, A.M. Hussain, Y. Huang, D.W. McOwen and E.D. Wachsman, ACS Appl. Energy Mater., 1, 1559 (2018).

[7] R. Leah, A. Bone, M. Lankin, A. Selcuk, R. Pierce, L. Rees, D. Corcoran, P. Muhl, Z. Dehaney-Steven, C. Brackenbury, M. Selby and S. Mukerjee, ECS Trans., 57, 461 (2013).

[8] R. Leah, A. Bone, P. Hjalmarsson, A. Selcuk, M. Lankin, M. Rahman, A. Clare, G. Reade, F. Felix, J. De Vero, X. Wang, S. Mukerjee and M. Selby, ECS Trans., 103, 679 (2021).
Fabrication and Characterization of Freeze-Cast Tubular Solid Oxide Cells
Authors: Du Yanhai , Woodson Theo , Panthi Dhruba
Published: September 2023

Increasing triple phase boundaries (TPBs) and reducing gas diffusion limitation in electrodes of solid oxide fuel cells (SOFCs) and solid oxide electrolysis cells (SOECs) have always been a goal for highly desirable electrochemical performance. Freeze-casting (also called ice-templating) is a promising method to produce hierarchically arranged porous ceramics with aligned and directional pores that could assist to reach such a goal. After reviewing the previous work on ceramic freeze casting, we focused on optimizing the processes to better engineer tubular supports for SOFC as well as SOEC applications. Although the optimized process does not have too many constraints on the types of ceramic materials (except particle size and surface area), we selected the commonly used 8 mol.% yttria stabilized zirconia (8YSZ)/NiO composite material set as a starting point. Cast slurry formulations, cast temperatures, slurry feeding methods and freeze-drying conditions were studied. Microstructures of the tubular parts prepared at various conditions were examined. Finally, as an example for SOFC application, the fuel cell performance was reported.

Figure 1
Enhancing the Catalytic Activity of Ce(Mn, Fe)O2 on a Perovskite-Based Electrode via Spraying for High-Temperature CO2 Electrolysis
Authors: Lee Sang Won , KIm Minkyu , Lee Seok Hee , Shin Tae Ho
Published: September 2023

Solid oxide electrolysis cells (SOECs) have tremendous potential to be highly efficient devices for high-temperature CO2 electrolysis. In general, the commonly used Ni-based cathodes suffer from inherent redox instability during direct CO/CO2 conditions. Therefore, the robust perovskite oxide La(Sr)Cr(Mn)O3 (LSCM) is suggested as an alternative due to its excellent coking resistance. However, the LSCM cathodes are limited due to their poor catalytic activity on CO2 reduction. [1] To alleviate this problem, the Ce(Mn, Fe)O2 (CMF) was added as a catalyst owing to the surface oxygen vacancy of CMF, which accelerates the chemical adsorption of CO2. [2] In this study, the solid direct injection process by ultrasonic spraying (SDI-USSP) is employed to fabricate the nano-decorated embedded CMF on LSCM surface as enhancing catalytic activity. The highly decorated electrode surface with CMF nano catalyst was embodied by an advanced one-step SDI-USSP without any complicated pretreatment and infiltration. We also analyzed the uptake of the catalytic activity and the ratio of CMF nanocatalysts through comparison with conventional composite electrodes. Consequently, when applied as a cathode for electrolyte-supported cells, the performances are measured at 1123 K, exhibiting a maximum power density of 1.349 W cm-2 in fuel cell mode (H2) and electrolysis performance of 2.756 A cm-2 at 1.5 V in CO2 reduction with high faradaic efficiency of nearly 94 %.
Short Term Silver Electrode Microstructure Changes Under Epoxidation Conditions for Solid Oxide Electrolysis Cells
Authors: Jenkins Cody , Tian Jiashen , Milcarek Ryan J
Published: September 2023

Ethylene epoxidation is an important reaction to form ethylene oxide (EO), which is a precursor to many other critical chemicals. This study links short-term EO production to the effects on the microstructure of Ag/yttria-stabilized zirconia cells with and without an electrochemically promoted catalyst (EPOC). Nano scale features called striations were observed using a Scanning Electron Microscope on the silver under all reaction conditions tested. While appearing in both cases, the striations for the EPOC case are finer in size (~200 nm) compared to the no current case (~400 nm). These features did not appear when epoxidation conditions were not present. Striation formation was further linked to the epoxidation reaction through electrochemical impedance spectroscopy (EIS) and gas chromatography. Ethylene conversion to EO declines over the course of hours as striations form, indicating that striations have a negative influence on the reaction. Striation formation further effected the electrochemical performance of the cells, resulting in the low frequency depressions on EIS to shrink in both cases after 10 hours of epoxidation.
Cathode Surface Segregating Modification for Boosting Oxygen Reduction Reactions: Coupling Theory and Experiment in Proton Conducting Solid Oxide Fuel Cells (H-SOFCs)
Authors: Xu Xi , Bi Lei , Skinner Stephen J
Published: September 2023

The surface electrochemical catalysis reaction is complex due to the unpredictable surface morphology and severe reaction environment, especially for cathodes in proton conducting solid oxide fuel cells (H-SOFCs) where water vapor is generated and evaporated at a high operating temperature. The first-generation cathode materials (LaxSr1-xMO3-δ, M=Fe, Co, Mn) tend to have A-site cation segregation, and this segregation layer reduces the performance. Surface segregation phenomena tends to be ignored by computer simulations because surface termination is described as a highly crystallized layer, misleading the development of material computing science. Therefore, a combination of theory and surface investigation is essential for future work in this community. In this work, we use density functional theory (DFT) for designing a higher-performing cathode material, La0.35Bi0.15Sr0.5FeO3-δ (LBSF), for improvement of both bulk and surface electrochemical character in an intrinsic manner, predicting a candidate material with good performance that can be used in solid oxide proton conducting fuel cells (H-SOFCs). By combining a sensitive surface analysis technique, low energy ion scattering (LEIS), surface segregation is finely considered and determined that the particles are fully covered with a Sr segregation layer on the outer most surface. Aberration-Corrected transmission electron microscopy (ACTEM) is also applied and shows an amorphous structure at the particle edge. With the determination of this segregation layer, a reality-closed model is given, and related surface reactions are modelled based on this layer instead of a conventional cleaved, well-crystallized surface. Also, as bismuth diffuses towards the surface due to the lone pair effect, the segregation becomes an oxygen reduction reaction preferred layer instead of a blocking layer. After computational prediction and surface analysis, LBSF is successfully applied into H-SOFCs and shows excellent performance with a peak power density of 1630 mW cm−2 at 700 oC. In addition, long term stability tests were conducted to ensure stability in future commercial use, and the experimental results show that LBSF works stable under extremely high temperature operating environments. In addition, a full cell was stabilized for about 300 hours, indicating a potential commercial application in the future.
Recovery and Delay of Impurity-Induced Poisoning of Oxygen Exchange Kinetics in Mixed Conducting Oxides Via Controlled Surface Acidity
Authors: Seo Han Gil , Tuller Harry L.
Published: September 2023

The oxygen exchange kinetics in mixed conducting oxide surfaces are critical to a variety of energy-related technologies, including solid oxide fuel/electrolyser cells (SOFCs/SOECs), permeation membranes, batteries, and sensors. Such devices, however, commonly suffer from performance degradation from impurity-poisoning during long-term operation, for example, chromia poisoning in SOFCs from metal interconnects or silica from furnace refractories. The acidity/basicity of binary additives has recently been found to be a sensitive descriptor for determining the oxygen exchange coefficient (kchem
) of mixed ionic/electronic conducting oxides (MIEC), systematically varing by over 6 orders of magnitude via controlled surface infiltration with binary oxides. These huge variations in kchem
are attributed to changes in surface electron concentration induced by the additives.

Inspired by these ideas, in this work we first demonstrate the ability to recover the oxygen exchange kinetics of MIEC oxides (e.g. Pr0.1Ce0.9O2-δ
(PCO) and Sr(Ti,Fe)O3 (STF)) by counteracting acidic infiltrant’s impact on degradation, e.g. by chromia or silica, by compensating with a basic infiltrant like lithia or calcia. Further, we further demonstrate the ability to enhance impurity tolerance of MIEC oxides by pre-coating basic additives onto the electrodes. Such pre-treatments not only markedly improve the initial kchem
of the pristine MIEC oxides, but markedly lower the rate of degradation induced by subsequent coatings with acidic poisons. Electrical conductivity relaxation measurements on porous MIEC specimens were used to examine the impact of infiltrants on kchem
. In parallel, the area-specific resistance of screen-printed symmetric cells (cathode|electrolyte|cathode) were examined by electrochemical impedance spectroscopy.
Microstructural Analysis of Solid Oxide Electrochemical Cells via 3D Reconstruction Using a FIB-SEM Dual Beam System
Authors: Jang Seungsoo , Bae Kyung Taek , Kim Dongyeon , Yu Hyeongmin , Oh Seeun , Im Ha-Ni , Lee Kang Taek
Published: September 2023

The 3D reconstruction based on tomography technology enables quantitative and qualitative microstructural analysis of complex multiphase oxide structures. This powerful approach is widely investigated in diverse areas, in particular, gaining more importance in solid oxide electrochemical cells (SOCs) fields. SOCs are promising energy conversion devices with high efficiency, however, they have complex and porous/dense multilayered microstructures, which are closely related to the electrochemical reaction in the electrodes, thus, one of the major factors determining overall output performance of SOCs. Therefore, it is necessary to quantify the microstructural parameters of the cell. A focused ion beam-scanning electron microscope (FIB-SEM) dual beam system is one well-established method to obtain tomographic images to reconstruct 3D microstructures. It has an appropriate scale of tenth of nm to μm-level with high spatial resolution to represent the microstructural characteristics of the SOC electrodes. This presentation is intended to introduce our progress on 3D reconstruction techniques to quantitatively analyse SOCs, obtaining microstructural features such as particle size, connectivity, tortuosity, contact area, and triple phase boundary density. These in-depth analyses are helpful in extensively understanding electrochemical behavior in SOC electrodes.
Comparison of Carbon Deposition and Removal from Ni-YSZ and Ni-BCZY Composites Using Operando Optical Methods
Authors: Maza William A , Steinhurst Daniel , Pomeroy Elias D , Kee Robert J. , Ricote Sandrine , Walker Robert A. , Owrutsky Jeff
Published: September 2023

Solid oxide fuel cells (SOFCs) are attractive devices for power generation because they can operate with a variety of fuels, including H2, hydrocarbon fuels, biogas, and syngas. Conventional SOFC anode composites comprised of Ni-YSZ (YSZ = yttria-stabilized zirconia), however, suffer from performance degradation due to surface accumulation of carbon from hydrocarbon cracking. Alternative electrolyte materials such as yttria-doped barium cerate/zirconate mixtures (BCZY) offer the promise of reduced carbon formation over the Ni-BCZY electrode and lower operating temperatures by the conduction of protons instead of oxide ions. In this study, 50%-50% Ni-8YSZ and 50%-50% Ni-BCZY27 composites were exposed to CH4 in the absence and presence of either CO2 or H2O. The degree of carbon deposition and mechanism of carbon removal in the absence of fuel was estimated in the presence of steam using operando Fourier transform infrared emission spectroscopy (FTIRES) and near-infrared thermal imaging (NIRTI) at 750 °C. Upon exposure to each fuel condition, carbon removal using steam results in more CO2 + CO product formation from Ni-8YSZ implying more carbon formation on Ni-8YSZ compared to Ni-BCZY27. Carbon removal of cells exposed to CH4 alone indicate limited formation and fast depletion of CO over Ni-BCZY27; depletion of CO2, however, happens more slowly. Depletion of CO and CO2 in the Ni-8YSZ system happens more gradually suggesting the deposition of carbon over Ni-BCZY27 occurs less readily and its removal is more facile through gasification. Interestingly, the cracking of CH4 over Ni-8YSZ is accompanied by a larger degree of cooling compared to Ni-BCZY27 whereas both dry and wet reforming result in similar cooling over Ni-8YSZ and Ni-BCZY27. The results will be discussed in the context of recent work using operando spectroscopies to characterize CH4 fuel utilization in Ni-8YSZ based SOFCs in the absence and presence of various reformers.
Effect of Water Vapor and Hydrogen Concentration on Power Generation Characteristics of Protonic Ceramic Fuel Cell
Authors: Nagata Yohei , Araki Takuto , Li Kunpeng , Ryogo Takatera , Murakami Takeru , Kuroha Tomohiro , Mikami Yuichi , Yamauchi Kosuke , Mori Masashi , Matsuda Ryuma , Kobayashi Shun
Published: September 2023

The proton and hole conductivities of BaZrO3-based perovskites depend on partial pressures of oxygen and water vapor. These conductivities affect the power generation characteristics of Proton Ceramic Fuel Cells (PCFCs) using the perovskite as an electrolyte. In this study, the effect of humidification conditions on the power generation characteristics of an anode-supported PCFCs was investigated.

The configuration of the anode-supported PCFC was La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode/BaZr0.8Yb0.2O3-δ(BZYb) electrolyte/Ni-BZYb anode. The diameter of the effective cathode area was approx. 10 mm. The cathode gas composition was fixed at 97% concentration of air and 3% concentration of water vapor. The concentration of water vapor in the anode gas was controlled to be 3-69%. The current density-voltage characteristics and AC impedance were measured by Bio-Logic SP-150.

In all water vapor concentration conditions, the cell showed the highest OCV (approximately 1 V) at 3% concentration of water vapor. However, the maximum power density was highest at 30% concentration of water vapor (346 mW/cm2). The highest maximum power density at 30% concentration of water vapor can be explained by the following reason. The OCV values decrease with increasing the concentration of water vapor because of decreasing the concentration of hydrogen. On the other hand, from the results of impedance measurements, the ohmic resistance of the cell decrease with increasing the concentration of water vapor because of increase of proton conductivity of the cell. Thus, the increase of cell voltage by increase of proton conductivity should be higher than the decrease of OCV values.

【Acknowledgements】

This presentation is the result of the research and development of ultra-efficient proton-conducting ceramic fuel cell devices, JPNP20003, funded by the New Energy and Industrial Technology Development Organization (NEDO), Japan. We would like to express our gratitude to all parties involved.
Effect of a-Site Cation Defect on Electrochemical Performance and Stability of La0.8Sr0.2Co0.2Fe0.8O3-
δ Cathode
Authors: Zhang Xuebai , Jin Yingmin , Dai Changsong , Su Delin , Xiong Yueping
Published: September 2023

The application of Solid oxide fuel cells (SOFCs) is restricted by the insufficient catalytic activity in oxygen reduction reaction and the impedance increase of cathode in long-term operation at medium and low temperature[1]. In this work, we prepare La0.8Sr0.2Co0.2Fe0.8O3-
δ (LSCF) nanofiber cathode material with different A-site defects by electrospinning technique, and systematically explore the influence of A-site cation defect on the electrochemical performance and long-term stability of LSCF cathode. The experimental results show that the cathode with La defects at A-site (La0.77Sr0.2Co0.2Fe0.8O3-
δ) obtains better electrochemical performance than the cathode with Sr defects (La0.8Sr0.17Co0.2Fe0.8O3-
δ). With the increase of the proportion of La deficiency at A-site, the long-term operation stability of LSCF cathode is improved, and Sr surface segregation is suppressed. However, excessive A-site deficiency cause lattice instability of LSCF, resulting in the separation of Co3O4, which reduces the electrochemical catalytic activity of LSCF cathode. Proper A-site defects can not only increase the oxygen vacancy of LSCF material, but also inhibit the Sr surface segregation, which makes La0.77Sr0.2Co0.2Fe0.8O3-
δ a promising optimized SOFCs cathode material.

Figure 1