bluuebunny/crossref_metadata_2025 huggingface dataset:
(Best Student Presentation) Accurate First-Principle Study of High-Entropy Materials for Lithium-Ion Batteries
Authors: Ting Yin-Ying , Kowalski Piotr M.
Published: September 2023

The availability of well performing and cost efficient energy storage devices is of utmost importance for a smooth transition to sustainable energy. Lithium-ion batteries (LIBs) have been successfully commercialized and widely used in various portable devices. Functional materials with higher voltages and greater capacity are needed to further boost the energy density of these batteries. Recently, high-entropy materials (HEMs), with their unique structural characteristics and tunable functional properties, are actively investigated by several research groups [1]. High-entropy alloys (HEAs) with superior mechanical properties were first reported about a decade ago. Afterwards, the concept was adapted to high-entropy ceramic (HECs), such as high-entropy oxides, which are promising materials for electrodes as well as electrolytes in LIBs [2-4]. These materials usually contain more than 5 metals in a single disordered phase [5]. HECs are constructed with different type of cations and anions. Their structural and electronic complexity represent a challenge to the computational methods. We discuss the refined Density Functional Theory (DFT)-based methods that are able to successfully describe the electronic structure of these materials. The correct assignment of oxidation states of transition metals is one of the challenges, and we will show importance of correct description of d orbitals for achieving this task. Besides, we will also discuss the cycling performance, as well as thermodynamic aspects of selected HECs [6,7]. Last but not least, we will briefly discuss how accurate atomistic simulations could accelerate design of high-performance materials for Li-ion batteries of the future.

[1] Zhang, R.-Z. & Reece, M. J. Review of high entropy ceramics: design, synthesis, structure and properties. J. Mater. Chem. A 7, 22148–22162 (2019).

[2] Lun, Z. et al. Cation-disordered rocksalt-type high-entropy cathodes for Li-ion batteries. Nat. Mater.
20, 214–221 (2021).

[3] Sarkar, A. et al. High entropy oxides for reversible energy storage. Nat Commun
9, 3400 (2018).

[4] Jung, S.-K. et al. Unlocking the hidden chemical space in cubic-phase garnet solid electrolyte for efficient quasi-all-solid-state lithium batteries. Nat Commun
13, 7638 (2022).

[5] Rost, C. M. et al. Entropy-stabilized oxides. Nat Commun
6, 8485 (2015).

[6] Cui, Y. et al. High entropy fluorides as conversion cathodes with tailorable electrochemical performance. Journal of Energy Chemistry 72, 342–351 (2022).

[7] Ting,Y. & Kowalski, P., Refined DFT+U method for computation of layered oxide cathode materials, Electrochimica Acta, in press.
Development of PCL-Based Gel Polymer Electrolyte for Li-Sulfur Batteries
Authors: Gomes Luisa Larissa Arnaldo , Mukerjee Sanjeev , Maxwell Derrick , Yang Kevin
Published: September 2023

Li-Sulfur batteries offer the next generation of energy storage beyond the current state of the art based on Li-intercalation with their high energy density (2640 Wh/kg) and S relative abundance on the earth's crust. Nevertheless, most Li-Sulfur battery systems use liquid electrolytes, which results in the formation of Li-metal dendrites and polysulfide redox shuttles resulting in the instability of the solid electrolyte interface layer, short-circuiting, poor cyclability, and self-discharge1. Our presentation will focus on efforts to create a polycaprolactone (PCL)-based gel polymer electrolyte (GPE) for Li-S batteries. GPE combines the high ionic conductivity of a liquid electrolyte with the polymer electrolytes' ability to block the redox shuttle and limit the Li-metal dendritic growth2. Furthermore, PCL provides for high electrochemical stability window (~5V vs. Li/Li+)3 and biodegradability that could ease the negative environmental impact associated with the battery industry.

Moreover, effect of ceramic additives like LiNO3 and Li7La3Zr2O12 for enhancing ionic conductivity, mechanical stability and minimize the redox shuttle effect is also examined. We anticipate that the gel can be engineered to provide the high conductivity of a liquid electrolyte and the solid-state properties needed to block the polysulfide redox shuttle and limit dendrite growth. By determining the optimal ratio of polymer, additives, and solvent in the PCL gel formulation, we hope to benefit from hybridized ceramic/polymer electrolytes: nanocomposites engineered to optimize the advantages of polymers and ceramics while minimizing their weaknesses.

References

Pervez, Syed Atif, et al. Journal of Materials Chemistry A32 (2020): 16451-16462.

Cui, Yingyue, et al. Chemistry–An Asian Journal(2022): e202200746.

Fonseca, C. Polo, et al. " J. Electrochem. Sci2.2007 (2007): 52.
Capture and Electrochemical Conversion of CO2 into Carbon Nanotubes Using Molten Alkali Metal Borates
Authors: Nitzsche Michael Philip , Bromberg Lev , Hatton T. Alan
Published: September 2023

Molten alkali metal borates have recently shown promise as high-temperature sorbents for capture of CO2 and acid gases. These molten salt sorbents enable realization of thermodynamic enhancements offered by conventional solid high temperature sorbents while resolving practical challenges such as morphological degradation. Prior studies have focused on regeneration of alkali borates through steam sweeping and thermal cycling. In this work, we demonstrate that mixed sodium-lithium borate salts as CO2 sorbents can also be regenerated electrochemically, producing valuable multiwalled carbon nanotubes (MWCNT) via electroreduction of captured CO2. Effects of cathode materials and operating conditions in CO2 electroreduction in molten sodium-lithium borate are quantified. By varying relative starting compositions of alkali borates and alkali carbonates, an optimal composition of borates and carbonates is determined, achieving high coulombic efficiencies and significantly higher CO2 uptake capacities than traditionally employed carbonate salts used for conversion of CO2 into CNTs in the desirable 550-650°C range.
Some Thoughts on Magnetoelectrocatalysis of Small Molecules
Authors: Leddy Johna
Published: September 2023

Electrons have properties of mass, charge, and spin. Spin engenders magnetic effects on electron transfer reactions. Many electron transfer reactions of small molecules such as oxygen, carbon dioxide and other molecules with a single carbon, and simple nitrogen species are slow.

Electrochemical potentials characterize transition state for electron transfer processes. This includes gradients in electrical potential and magnetic fields at the electrode solution interface.

Rates of reaction for small molecules at electrodes are considered in light of these gradients and recently developed quantitative models. Means to increase rates of electrocatalysis and magnetoelectrocatalysis are suggested. In some cases, slow electron transfer rates may be set by the inherent spin properties of the electrolysis reactants and products.

Thanks to the National Science Foundation (CHE-0809745 and CHE-1309366) and Army Research Office (W911NF-19-1-0208)) for support of this work.
Insights into the Reaction Energetics and Phase Stability of Electrocatalysts for Upgrading Sustainable Alcohols
Authors: Prajapati Aditya , Govindrajan Nitish , Sun Wenyu , Feaster Jeremy , Akhade Sneha A , Hahn Christopher
Published: September 2023

The energy efficiency of ambient electrolyzers is currently impacted by oxygen evolution reaction (OER) which not only consumes a significant amount of energy, but also produces oxygen, an intrinsically low value product. When paired with a desired cathodic reaction, such as CO2 conversion to value-added hydrocarbons, it is imperative to choose an anodic reaction that can utilize the energy supplied to the electrolyzer efficiently. Biomass alcohol oxidation has the potential to not only decrease the overall electrolyzer energy input by >50%, but also address critical needs for biomass conversion, another important 21st century non-fossil carbon resource. Here, we present the oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) as an alternative to OER, as this pathway not only decreases the theoretical overall energy input into the electrolyzer, but also produces FDCA, an important biomass-derived chemical building block for the sustainable polyester PEF, a compelling alternative to fossil-based PET which has a global market size of >30 Mt/yr. In this work, we show a synergistic experimental and computational catalysis framework to gain mechanistic insights into the reaction energetics of HMF oxidation on Ni-based catalysts. We experimentally evaluate the redox features of Ni on supports such as Au in a pH range of 10-13 as a function of Ni film thickness (<1-5 nm) to understand the intrinsic kinetics of HMF oxidation and the support effects on the reaction. Computationally, we compare the reaction energetics of OER and hydride transfer reaction of the HMF oxidation to understand the competing pathways on the anode and perform a bulk Pourbaix analysis as a function of strain caused by the presence of the support lattice to understand the phase stability of Ni oxides under oxidizing conditions. This systematic analysis could potentially serve as new guiding principles to design more energy efficient anodes to upgrade sustainable alcohols.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
(Digital Presentation) Moth-Eye Structured BiVO4 Photoanode with Improved Optical Properties for Efficient PEC Water Splitting Performance
Authors: Sung Hansang , Ju Sucheol , Lee Heon
Published: September 2023

Photoelectrochemical (PEC) water splitting, wherein infinite solar energy is used to produce hydrogen without CO2 emissions, is an ideal eco-friendly energy technology. The main reactions in PEC water splitting, the oxidation and reduction of water, are caused by the electron–hole pairs generated by solar energy; hence, the light absorption efficiency is a key parameter in PEC devices. In conventional thin-film-type photoanodes, absorption is limited owing to their high reflectance, which hinders their absorption and separation efficiency. Conversely, a moth-eye-structured photoanode exhibits an anti-reflection effect owing to its subwavelength structure, which significantly increases the light absorption efficiency. Hence, in this study, a densely packed moth-eye-structured BiVO4 photoanode with good light absorption properties was designed. It was fabricated via direct printing, e-beam evaporation, and V calcination. The light absorption of M-BVO increased to approximately 92% within the 300–500 nm wavelength range, and the absorption efficiency (ηabs) increased to 82.9%, indicating a 23.5% increase in comparison to that of flat BiVO4. The photocurrent density of M-BVO reached 2.98 mA cm−2 at 1.23 VRHE, which was 37.6% higher than that of flat BiVO4. These results show that the PEC efficiency can be significantly increased through moth-eye structuring, which suggests that research on nanostructures is essential for the manufacture of high-efficiency photoanodes.

Figure 1
The Good, the Bad and the Ugly of pH Microelectrodes
Authors: Mauzeroll Janine
Published: September 2023

pH micro electrodes have been around for many years with several architectures already reported. We will review the existing options critically providing guidance on their fabrication, advantages and limitations. We will also report a new fabrication method to produce Pd hydride pH microelectrode using a chemical approach to synthesize the Pd hydride. In contrast to electrochemically generated PdH microelectrodes, this chemically generated Pd hydride microelectrodes are longer lasting, allowing long-time localized pH measurements.
Flips: Fluidic Integration of Printed Sensors
Authors: Anderson Morgan J , Blair Jeffrey , Shimada Jared , Koehne Jessica E. , Ricco Antonio
Published: September 2023

As NASA’s manned exploration programs advance toward more challenging missions including Martian spaceflight and long-term space habitation, novel technologies must be adapted for astronaut health monitoring and diagnostics. Among the technologies currently under development, In-Space Manufacturing (ISM) is an attractive approach because it mitigates the need to include multiple prefabricated sensors in spaceflight payloads instead allowing production of sensors on an as-needed basis by additive manufacturing techniques such as 3D-printing and inkjet printing. Several examples of ISM sensors have been demonstrated recently. However, liquid sample handling in microgravity environments produces several challenges, and consequently all liquid handling must be contained in a closed environment to prevent sample loss and contamination of crew quarters.

Here we demonstrate the development of an ISM-compatible manifold for the fluidic integration of printed sensors (FLIPS). Our approach to the development of the FLIPS manifold is to identify components that cannot be manufactured using ISM techniques, and to fabricate all other components using flight-heritage 3D-printing and CNC cutting. FLIPS includes a mounted peristaltic pump and switch valve with measurements performed on off-the-shelf screen-printed carbon electrodes. We demonstrate the performance of the manifold with a model redox species (ferrocene carboxylic acid). Finally, we show the potential application as an integrated healthcare diagnostic system by detection of a renal health biomarker, alkaline phosphatase.

This capability is necessary to ensure the success of ISM sensors for liquid samples and allows further customization of sensor architectures. The FLIPS platform demonstrates the applicability of ISM to complex fluid handling that will be adopted in future NASA missions.
Employment of Aptamer Recognition Elements in Paper Lateral Flow Assays for Detection of a Traumatic Brain Injury Biomarker
Authors: Tan Weirui , Hang Yingjie , Wu Nianqiang
Published: September 2023

Traumatic brain injury (TBI) is one of consequences of outside violence against head, triggering brain function degradation and loss. As compared to conventional enzyme-linked immunosorbent assays (ELISA), paper lateral flow assays (PLFA) can rapidly detect TBI biomarkers in field or at emergency departments. This works shows molecular recognition elements (MRE) play a critical role in PLFAs. Our results show that aptamers have significant advantages over antibodies as MRE. Aptamer shows higher binding affinity, leading to higher detection sensitivity. Besides, aptamers are more stable, allowing for longer shelf life. In short, our work indicates that aptamers have a great promise in point-of-care testing tools due to their reliability, robustness, reproducibility, and massive production capability.
Development Progress of a 70% Efficient Hybrid SOFC-I.C. Engine Hybrid System for Stationary Applications up to 1 MW
Authors: Braun Rob J , Floerchinger Gus , Sullivan Neal P. , Vincent Tyrone , Danforth Robert , Bandhauer Todd , Garland Shane , Olsen Daniel
Published: September 2023

Flexible and dispatchable, high-efficiency power generation supplied with carbon-neutral renewable fuels is needed to help enable defossilization of the electric grid. Pressurized, hybrid SOFC systems fueled with hydrogen, biogas, or renewable natural gas can generate clean power at ultra-high efficiency. This presentation presents an update on the development progress of a full-scale, hybrid system that targets low cost (<1000 $/kW) and ultra-high efficiency (70%-LHV) distributed power generation for applications up to 1 MW. The system features mature, metal-supported SOFC technology and the system design, control, hardware integration, and demonstration activities are funded by the U.S. DOE ARPA-E INTEGRATE Program. Some of the more novel aspects of the system include the intermediate operating cell temperature (600°C) and internal reforming capabilities which enable excellent thermal management and effectively reduce air preheater duty by >60% over more conventional SOFC systems operating near 800°C. Pressurization of the system decreases area specific resistance (ASR) and increases stack power density, thereby lowering capital cost. The use of a gasified diesel engine converts the residual chemical exergy in the anode tail-gas from the SOFC to drive auxiliaries and produce net additional power. Furthermore, the syngas engine enables a simple engine after-treatment for achieving ultra-low engine emissions (NOx, CO, PM, UHC). Updates on critical hardware advancements around pressurized multi-stack, 30 kW fuel cell modules, low-speed high efficiency rotating equipment, and ultra-high efficiency power electronics are provided. Results from experimental testing, system design and layout, and demonstration test facility capabilities are presented and discussed. The presentation concludes with a techno-economic outlook for such power generation systems in various stationary applications, as well as comparison with competing distributed generation technologies, such as solar PV-battery systems, microturbines, stationary engines, and non-hybridized SOFC technologies.

Figure 1
Optimization of SOFC Anode Microstructure for Performance and Highly Scalable Cells through Graded Porosity
Authors: Ostrovskiy Yevgeniy , Saqib Muhammad , Hong Jaewoon , Wachsman Eric
Published: September 2023

The performance and durability of anode supported solid oxide fuel cells is heavily dependent on the porosity of their anode layer. An optimal amount of porosity is needed to achieve high performance without compromising the flatness, and by extension, the hermetic sealing of the cell. This presents challenges for commercialization, as anode porosity heavily influences the densification of the cells during sintering. In this work, the effect of pore former loading was evaluated on both cell performance and curvature. It was also found that anodes with an intermediate amount of pore former had the best performance but also the most curvature. The mechanism behind this was evaluated with an optical dilatometer. As expected, when cells were sintered with thicker anode support layers, they resulted in significantly flatter cells. Improvements to performance but not flatness were achieved with the use of graded porosity in the anode, with high porosity at the fuel side that decreased closer to the electrolyte. This effect was more pronounced at lower temperatures and fuel ratios, further demonstrating that this is a more efficient microstructure for the anode than a typical anode with uniform porosity. The use of graded porosity was then evaluated as a means of improving the performance of thicker anodes, to take advantage of their greater flatness and mechanical strength. Unfortunately, thicker anodes exhibited a significant drop in performance. It was found that the greater distance for gas diffusion in thicker anodes means that a different microstructure is needed for efficient gas flow and charge transfer. In the case of thicker anodes, it was found that having two anode regions, one thinner region with moderate porosity adjacent to the anode functional layer and one with high porosity making up the bulk of the anode resulted in the best performance. This allows sufficient fuel flow in a thicker anode, without significantly reducing the activity of the anode. In this way, this anode microstructure behaves similarly to an anode functional layer, which is well known to improve fuel cell performance. While graded anode microstructures have been reported before, there have been few, if any, studies that evaluated both their performance and flatness simultaneously. Optimization of anode porosity in anode supported cells is essential to improving both their performance and reliability, which are necessary for widespread adoption of SOFCs.
Ni-YSZ Electrode Stability in Solid Oxide Electrolysis Cells Operated in 90-98% Steam
Authors: Le Long , Coyle Christopher , Seymour Lorraine , Zaengle John , Escobar Julian , Liu Tian , Bao Jie , Meinhardt Kerry , Marina Olga A
Published: September 2023

Ni-YSZ electrode-supported SOECs were tested at 750 and 800oC using extremely high steam concentrations, 90, 95, and 98%. The performance was compared to SOECs tested in 50% steam with 50% hydrogen. Multiple cells were tested simultaneously with several repeats, all cells configured into a single furnace for each test to ensure a reasonable side-by-side comparison and results reproducibility. The Ni/YSZ electrodes was reduced by hydrogen in situ at each operating temperature and then 50-98% steam was added. Cells were tested at a fixed current or voltage for 1000-3000 hours. The electrochemical impedance data was periodically collected followed by the DRT analyses to identify any changes in polarization losses in time. Minimal to no changes in cell performance in time was observed when compared cell operation in 90+% steam vs 50% steam. Slightly higher degradation was seen for cells tested at 800oC vs those tested at 750oC during the initial 500 hours. After the initial break-in period, the degradation rates for all cells in the following >1000 hours remained the same.

A separate set of tests was performed to characterize break-in period and to understand how the initial Ni thermal aging at different temperatures affects the time to a pseudo steady-state, i.e., if the Ni aging/conditioning could be used to accelerate the initial degradation and shorten break-in. Symmetrical cells with two Ni-YSZ electrodes on each side of 10 micron YSZ electrolyte were also tested.

The extensive SEM/EDS analyses were performed on all cells to quantify the Ni particle size and describe any microstructural changes. The 2-dimensional SEM images were reconstructed into the 3D microstructures to calculate the triple phase boundary density, species transport paths tortuosity, and particle/pore size distribution.
Scale Up and Coupling of the MOXIE Solid Oxide Electrolyzer for Both Terrestrial and Space Applications
Authors: Hollist Michele , Larsen Dennis , Gomez Abel , Hafen Tyler , Czernichowski Piotr , Valdez Skyler , Lingen Jeffrey , Izatt Becca , Pike Jenna , Hartvigsen Joseph , Elwell Jessica , Elangovan S
Published: September 2023

The Mars Oxygen ISRU Experiment (MOXIE) is a first of its kind demonstration of in-situ resource utilization technology to produce propellant and breathable oxygen from the Mars ambient carbon dioxide. The use of Lunar and Martian resources represents a significant opportunity to reduce the cost of launch from Earth, enabling propellant production for space refueling, and allowing for life support of manned missions to the Lunar and Martian surfaces.

Since developing the Solid OXide Electrolysis (SOXE) stacks for the Mars 2020 MOXIE program in 2017, the OxEon team has made significant advancements in scale and capabilities of the SOXE stack technology used in that system. Newer variants have a five-fold larger cell area and a 6.5-fold increase in cells per stack, for a stack scaled 33-times the 0.5% scale of the device in MOXIE. Six of these OxEon mission-scale SOXE stacks will produce 30 tons of propellant oxygen to fuel a Mars Ascent Vehicle (MAV) in the 19-month window between landing an unfueled MAV pre-supply mission and the next launch opportunity for the first crewed Mars Mission, meeting target requirements for a return mission. OxEon has built and demonstrated systems with mission-scale stacks for both Lunar and Martian applications. A system for the production of propellant H2 and O2 from Lunar ice was successfully tested in a cryo-vac chamber at the Colorado School of Mines in 2022. Another mission-scale demonstration system is scheduled to demonstrate production of O2 and methane from Martian H2O and atmospheric CO2 at Jet Propulsion Laboratory in 2022.

In addition to SOXE/SOFC systems, the OxEon technology portfolio also consists of a low energy plasma reformer capable of producing sygnas from a variety of hydrocarbons and a modular-scale Fischer-Tropsch reactor for the production of liquid fuels from syngas. These technologies allow OxEon to provide a wide range of terrestrial energy solutions. A DOE Bioenergy Technologies Office (BETO) funded system is currently being fabricated to demonstrate the conversion of both CO2 and CH4 in anaerobic digester gas to liquid transportation fuels. This will be accomplished using an SOEC system to convert steam and CO2 to synthesis gas. OxEon’s plasma reformer will be used to convert methane to synthesis gas, using the plasma to catalyze the reaction of methane with steam and oxygen, supplied in part by the byproduct oxygen from the electrolysis system. The syngas from the plasma reformer and electrolysis systems are then combined to produce liquid fuels in the Fischer-Tropsch (FT) reactor.

Figure 1
Exploring Solid Oxide Electrolysis Cell Design for an Optimal Flow Distribution and Thermal Management
Authors: Jimenez-Martín Gonzalo , Judez Xabier , Aguado Mónica , Garbayo Iñigo
Published: September 2023

Climate crisis and the subsequent increase of fossil fuels prices have encouraged the search for alternative and renewable energy sources. In this scenario, the use of hydrogen as green energy carrier is nowadays regarded as one of the keys to achieve the transition to a fully renewable energy system. Among the existent and commercial technologies to produce green hydrogen, solid oxide electrolysis (SOE) outstands due to their high efficiency and the possibility of operate in reversible mode, i.e on electrolysis mode to produce hydrogen and on fuel cell mode (SOFC) to generate power from stored hydrogen. However, large-scale commercialization of these devices is still to-be-realized, mainly hindered by their short life time caused by degradation problems.

Apart from a correct materials selection and optimal microstructural design, uniform gas flow distribution along the cell is necessary. This is not only essential to reach higher performance but also to ensure good temperature distribution and minimize hotspots that would accelerate degradation. Therefore, cell design should be carefully optimized. For this purpose, replacing experimental cell design by computer modeling and simulation has been presented as a cost-effective alternative. In this sense, computational fluid dynamics (CFD) is a powerful tool that accurately predicts the behavior of the cells in diverse scenarios. CFD uses numerical analysis to solve the equations that define the behavior within the cells, including mass, species, momentum, energy and current conservation as well as electrochemical and heat transfer models that govern SOE behavior.

In this work, strategies to optimize cell design and their implementation by means of ANSYS Fluent® commercial CFD software are presented. These strategies have been classified into two categories: i) modifying gas manifolds and ii) modifying internal gas channels. On one hand, the strategies related to manifold design include acting on the number of inlets, outlets and its type (i.e open to ambient or pipes). On the other hand, the strategies related to internal gas channels design involve using different interconnect plate geometric features such as rectangular or cylindrical ribs. By changing these cell features, significant improvements in flow distribution and minimized thermal gradients and pressure drop are observed. Simulations conclude that manifolds are the most influential cell feature in terms of flow, thermal and pressure drop distribution, obtaining that a simple modification in the number of inlets and outlets can conduct to normalized mass flows near to the unit, thermal gradients below 1 K/cm and a negligible pressure drop.

Figure 1
Oxygen Non-Stoichiometry and Point Defect Equilibria in (La1/6Pr1/6Nd1/6Gd1/6Ba1/6Sr1/6)MnO3-
δ
Authors: Bishop Sean R , Zhang Dawei , Liu Cijie , Li Wei , Salinas Perla A , Smith Andrew I , Coker Eric N , De Santiago Héctor A , Liu Xingbo , McDaniel Anthony H , Luo Jian
Published: September 2023

Compositionally complex oxides (CCOs), also referred to as high entropy oxides, have several different cations (typically 5 or more) occupying a single site. CCOs have shown unique dielectric, ionic conductivity, and thermal conductivity properties, in addition to promising electrochemical properties for solid oxide fuel cells (SOFCs) [1,2]. In this work, the A-site of the common SOFC cathode La0.8Sr0.2MnO3-δ (LSM) is modified with additional lanthanide and alkali elements, resulting in the composition (La1/6Pr1/6Nd1/6Gd1/6Ba1/6Sr1/6)MnO3-
δ. Typically, the average lattice parameter is correlated with bond length and strength, and thus energetics of oxygen vacancy formation energy. In the compositionally complex system, there is a wide range of cation radii on the A-site and so bond strengths are expected to vary significantly, resulting in a distribution of oxygen vacancy formation energies. Initial results have shown that the amount of oxygen released during reduction is significantly greater for the studied CCO in comparison with La2/3Sr1/3MnO3-δ, the latter having the same amount of total acceptor dopant and with a similar lattice parameter as the CCO. The significant enhancement in oxygen loss is an indicator of a lower reduction enthalpy and suggests a significant impact from atomic structure that is not captured in long-range structure parameters (i.e., average lattice parameter). The oxygen non-stoichiometry measured by thermogravimetric analysis in ~10-5 – 1 atm O2 at 1200 oC – 1450 oC will be presented and the point defect equilibria analysis will be discussed. Comparisons with existing high temperature experimental and modeling studies on LSM will also be discussed.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525

References

[1] Xu, Y., et al., J. Adv. Ceram., 11 (2022) 794, DOI:10.1007/s40145-022-0573-7

[2] J. Dabrowa, et al., J. Mater. Chem. A, 8 (2020) 24455; DOI:10.1007/s40145-022-0573-7
Optimizing Bilayer Electrolyte Thickness Ratios for High Performing Low-Temperature Solid Oxide Fuel Cells
Authors: Pesaran Alireza , Hussain A. Mohammed , Ren Yaoyou , Wachsman Eric
Published: September 2023

Over the last several years, significant developments have been made in bilayer electrolytes (e.g. GDC(Ce0.9Gd0.1O2-δ)/ESB((Er0.20Bi0.80O1.5)) suitable for low-temperature operating solid oxide fuel cells (SOFCs). Such bilayer electrolytes offer the potential for developing high performing LT-SOFCs by lowering the ohmic area specific resistance (ASR), and by improving the open circuit voltage (OCV) of mixed ionic/electronic conducting (MIEC) type electrolyte (e.g., GDC). However, optimizing the thickness ratio of the bilayer electrolyte is essential to achieve high power densities at low-temperatures (650-500 ℃). Here, we made a systematic study by varying the thickness ratios between GDC and YCSB((Bi0.75Y0.25)1.86Ce0.14O3±δ) bilayer electrolytes on an anode-supported LT-SOFCs, in all cases, the maximum power density (MPD) of the bilayer electrolyte cells is higher than pristine GDC based cells with reduced ohmic ASR values. Specifically, a high MPD of ~1 W/cm2 at 650 ℃ was achieved on a GDC(20μm) / YCSB(12μm) bilayer electrolyte based SOFC, which is 62% higher than pristine GDC based SOFC (0.64 W/cm2) operating on humidified H2 as fuel. Such enhancement is due to the 9.3% improvement in OCV (from 0.791 to 0.865 V) and a considerable 36% reduction in ohmic ASR values (from 0.094 to 0.069 Ω.cm2). Such reduction in ohmic ASR of the GDC/YCSB bilayer electrolyte SOFCs is due to the increase of GDC electrical conductivity as a result of lower pO2 at the interface of YCSB and GDC, and hence, must be considered in optimizing the thickness ratio of the bilayer electrolyte for achieving higher power density SOFCs.

Figure 1
Numerical Analysis of Humidification Condition Effects on Protonic Ceramic Fuel Cell Performance Considering Concentration Overpotential
Authors: Li Kunpeng , Ryogo Takatera , Nagata Yohei , Murakami Takeru , Araki Takuto , Okuyama Yuji , Mori Masashi
Published: September 2023

Protonic ceramic fuel cells (PCFCs) show relatively high performance at intermediate temperature range (400–600 °C) due to high proton conductivity in electrolyte. However, besides proton, other charges such as electron hole and oxygen vacancy can also be conductive in PCFCs. Especially, the hole conductivity will induce a hole current leakage so that current efficiency and power density will decrease. Besides the operating temperature, the conductivities of proton and hole are also strongly affected by the partial pressures of steam and oxygen in the PCFC [1,2]. Higher steam partial pressure leads higher proton conductivity, so that a higher power density can be expected. However, other influences such as concentration overpotential may be non-negligible. Furthermore, the proton and hole current density are affected by defect concentrations differences between two surfaces of the electrolyte membrane. Numerical simulation method is powerful tool for dealing with the complicated conditions in a PCFC mentioned above.

In the present study, the influences of steam partial pressure on a BaZr0.8Yb0.2O3−
δ

(BZYb20) electrolyte are investigated. Specifically, to reveal the currents induced by the electrostatic potential and gas concentrations, Nernst-Planck model is selected. To relatively obviously reveal the steam concentration influences on the PCFC performances, low (3%) and high (69%) humidification conditions of H2 fuel gas are adopted. The results in Fig. 1(a) and 1(b) show the simulation and experimental current-voltage characteristics under 3% and 69% humidification conditions, respectively. The green solid and dotted lines are external and proton current densities considering concentration overpotential influence, respectively. The blue lines express external current density when no concentration overpotential in the numerical model. The red circles are the measured data. At low steam partial pressure, the simulation results well reproduced the experimental data without concentration overpotential consideration. However, an obvious deviation was found between simulation and experimental results when neglecting concentration overpotential in the simulation model. The performances such as open circuit voltage (OCV) and hole current leakage (difference between proton and external current density) are influenced by the steam partial pressure.

References

[1] K. Li
et al
., Int. J. Hydrogen Energy, 45 (2020), 34139-149.

[2] Y. Okuyama,
et al
., J. Hydrogen Energy, 39 (2014), 20829-36.

Figure 1
(Invited) Reach for the Sky: Solid Oxide Fuel Cell Hybrid Systems Enable Carbon-Neutral Flight in ARPA-E’s REEACH Program
Authors: Tew David , Gore Colin , Lecoustre Vivien , Radhakrishnan Rakesh
Published: September 2023

The carbon-neutral economy of 2050 may rely on several sustainable fuels, including hydrogen, ammonia, and renewable hydrocarbons. Solid Oxide Fuel Cells (SOFCs) deliver value for each candidate carbon-neutral fuel thanks to their inherent fuel flexibility and high efficiency. This talk examines the additional benefits that can be realized in hybrid systems comprised of an SOFC with an engine bottoming cycle. Developments in ARPA-E’s REEACH program involving SOFC-turbogenerator hybrids for electrified flight will be discussed. The interplays between design and operation of system components can significantly impact the energy storage and power generation (ESPG) system metrics. Modeling work has been performed to inform hybrid system design and will be presented. Finally, next steps for hybrid system deployment at commercial scale will be discussed.
A Comparative Study of the Performance and Electrode Processes of Solid Oxide H2O Electrolysis and CO2 Electrolysis
Authors: Liang Jingjing , Han Minfang , Ni Meng
Published: September 2023

The significance of converting CO2 into valuable feedstock is highly emphasized with the carbon neutrality vision and solid electrolysis cell has been regarded as a promising technology to convert CO2. However, it is far from its industrial application due to the severe degradation. In this paper, a degradation phenomenon was reported on both a button cell and an industrial size cell. Both cells suffered severe degradation during a short-time operating of CO2 electrolysis. The comparison of performance before and after degradation revealed significant differences between H2O electrolysis and CO2 electrolysis in terms of electrode processes and it was indicated that the interface of fuel electrode and electrolyte was the place that was severely damaged. Finally, a safety operating voltage interval was advocated to suppress the degradation.
CO2 Capture and Concentration Process by Solid Oxide Electrochemical Cells
Authors: Bian Wenjuan , Zhao Zeyu , Wu Wei , Ding Dong
Published: September 2023

To decarbonize the transportation sectors, the use of atmospheric CO2 as a chemical feedstock has attracted tremendous interest from industries and academia in recent decades due to its potential to address the current challenge on global warming and climate change. The carbon capture, utilization, and sequestration technologies by electrochemical cells are being developed and investigated to reduce the energy requirement. Here, we develop and demonstrate an alternative solid oxide electrochemical cell configuration with hybrid electrolyte membrane electrode assembly (HE-MEA) for the separation and capture of CO2. This process is optimized by tuning electrolyte compositions and operating conditions to maximize CO2 capture efficiency. The working mechanism of cathode was investigated by advanced characterization techniques and resulted in the better material designs. The present study paves a way for CO2 capture at elevated temperatures.
Modeling and Analysis of Polarization Losses in Solid Oxide Fuel Cells with Linear Siloxane Contamination
Authors: Rukmini Adrija , Ghotkar Rhushikesh , Riley Derall , Tian Jiashen , Milcarek Ryan J
Published: September 2023

In this study, the degradation of solid-oxide fuel cells (SOFC) nickel-yttria stabilized zirconia anode under siloxane contamination is examined. The experiments were conducted inside a furnace heated to 800°C with an Ni-YSZ-supported (Nickel-yttria-stabilized zirconia) fuel cell. A fuel source with a flow rate of 20 mL/min of hydrogen gas (66.3%), 10 mL/min of nitrogen gas (33.2%) and 0.15 mL/min (0.5%) of L4 siloxane was fed to the anode. Air was supplied to the cathode. Polarization losses are recorded at intervals of 30 minutes over a period of 3 hours. The polarization losses (activation, ohmic, and mass transport) are modeled with the parameters α and δ. The model is fitted to the experimental polarization curve, to understand how the siloxane degrades the SOFC performance with time. Ohmic losses are dominant in the anode due to much higher anode thickness (380 μm) compared to electrolyte thickness (13 μm). Activation losses vary with α, which decreases from 0.31 to 0.25, significantly lower than the accepted value of 0.5 found in existing literature. The current density is limited by mass transport losses at higher current densities (limiting current density j). Mass transport losses vary with both δ and α. The value of δ, which represents the diffusion layer thickness, varies from 45 μm to 66 μm. The results of the model indicate that the total polarization losses increase for each subsequent time interval, with a total increase of approximately 45% from 0 to 180 min. Activation loss dominates the polarization losses initially, but decrease over time while mass transport losses increase. With current density being constant at 500 mA/cm2, the activation losses decrease from 58% to 55%, ohmic losses decrease from 28% to 20% and mass transport losses increase from 14% to 21% of the total polarization loss over a period of 180 mins.
A-Site Deficient Lst-Based Perovskite Fibers with Ni Exsolution for Reversible Solid Oxide Cells
Authors: Yang Jiaming , Sun Yueyue , Fu Lei , Liu Zhengrong , Zhou Jun , Wu Kai
Published: September 2023

Reversible solid oxide cells (RSOCs) as new energy converting devices with superior conversion efficiency can operate in both fuel cell (FC) mode and electrolysis cell (EC) mode. However, the main challenges for fuel electrode materials are poor electrochemical performance and limited durability due to the sluggish hydrogen catalysis kinetics. Here, we demonstrate an advanced fiber-structured LaxSrxTi0.9Ni0.1O3-δ (LSTNx) architecture with a series of A-site deficiency (x=0.5, 0.45, and 0.4), which can be applied to reversible solid cells as a promising candidate of fuel electrode materials. LSTNx fibers decorated with Ni nanoparticles (NPs) were fabricated via electrospinning technique and in-situ exsolution method. A-site deficiency played a critical role in Ni exsolution and the morphology of LSTNx nanofibers. La0.4Sr0.4Ti0.9Ni0.1O3-δ fibers with moderate A-site deficiency displayed homogeneous Ni NPs on the surface and excellent stability at 800℃ in pure H2. A single cell with LSTN0.4 fuel electrode (~40 μm) | GDC barrier layer (~0.5 μm) | SSZ electrolyte (~250 μm) | GDC barrier layer (~0.5 μm) | composite LSCF-GDC air electrode (~40 μm) exhibits maximum power density of 547.44 mW·cm-2 at 800℃ in wet H2 and the current density of -1.351 A·cm-2 under the potential of 1.5 V in 50% H2O/H2 atmosphere. The 5-cyclic long-term reversible tests of FC and EC modes were carried out under the potential of 0.5/1.5 V for 60 h, respectively. The current density degradation was approximately 0.67% in EC mode and 2.73% in FC mode after 5-cyclic reversible tests in LSTN0.4 single cells, suggesting a reliable fiber-structured architecture for RSOCs.

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Inhibiting in Situ Phase Transition in Ruddlesdenpopper Perovskite Via Tailoring Bond Hybridization for Oxygen Ion Conduction
Authors: Han Ning , Zhang Xuan , Guo Xiangyu , Liu Shaomin , Fransaer Jan
Published: September 2023

Owing to the excellent physical and chemical properties, mixed ionic-electronic conducting (MIEC) oxide materials, especially Ruddlesden-Popper (RP) perovskite oxides with the chemical formula of An+1BnO3n+1, are interesting materials for gas separation, solid oxide fuel/electrolysis cells, polymer electrolyte fuel cells, lithium-ion battery, sodium-ion battery, zinc ion battery and metal-air battery. The in-situ phase transition at different temperatures is a common phenomenon for these MIEC oxide materials, which generally exerts a great influence on the properties and functionalities of these materials and finally determines their performance in various applications. However, the in-depth understanding of the mechanism of phase transitions is still limited so far. Element-doping has been recognized as a facile and efficient strategy to improve the oxygen ionic or electronic conductivity or to stabilize the crystal phase structure (inhibiting both ex-situ and in-situ phase transitions) favorable for oxygen ion conduction. Herein, the ex-situ collapse at room temperature of crystal structure together with the generation of impurities in orthorhombic Pr2NiO4 through Mo doping are observed as the rearrangement of praseodymium atoms-based lattice deformation, which could be attributed to the Mo-induced destabilization of the Pr2NiO4 systems. Noteworthy is that, such effect can be prohibited by controlling the doping contents, and the resultant materials would give rise to the inhibition of in-situ phase transition (high temperature) from low order Pr2NiO4 (An+1BnO3n+1 (n=1)) to high order Pr4Ni3O10 (An+1BnO3n+1 (n=3)) by adjusting bond hybridization at the phase interface. Mo-doping can influence the covalent interaction between praseodymium and oxygen and then promotes the mobility of interstitial oxygen. Pr2Ni1-xMoxO4+
δ were further developed as oxygen separation membrane to help further evaluate the performance of oxygen ion conductivity. In Pr2Ni1-xMoxO4+
δ, Mo doping level of x = 0.05 resulted in an oxygen permeation flux of 3.35 mL min-1 cm-2 at 1000 °C, comparing favorably with the literature. Furthermore, membranes made with Pr2Ni0.95Mo0.05O4+
δ showed high permeation stability in air or helium, and exhibits high CO2 tolerance without obvious decline of the oxygen permeation flux during 500 hours at round 900 °C. This work advances our understanding of the ex-situ and in-situ phase transitions of Pr2NiO4-based RP perovskite materials and shows how Mo doping can stabilizes the in-situ phase structure and improves the mobility of interstitial oxygen.

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Development of Protonic Ceramic Fuel Cell Using BaZr0.2Yb0.8O3-δ as the Electrolyte
Authors: Kuroha Tomohiro , Yamauchi Kosuke , Mikami Yuichi , Okuyama Yuji
Published: September 2023

Protonic Ceramic Fuel Cells (PCFCs) are attracting attention as next-generation fuel cells that are expected to have lower operating temperatures and higher power generation efficiency than SOFCs. We have reported that BaZr0.8Yb0.2O3-δ does not chemically react with NiO used as a fuel electrode at 1475°C, which is the sintering temperature of the cell, and that the fuel cell can be fabricated by the tape casting method and the fuel electrode and electrolyte co-firing method used in industrial production processes for SOFCs and electronic components. This report describes issues that need to be resolved for the practical application of this cell.

Fuel cells were fabricated by laminating green sheets prepared by the tape casting method and co-firing the electrolyte and fuel electrode together. For the air electrode, La0.6Sr0.4Co0.2Fe0.8O3-δ and La0.6Sr0.4CoO3-δ, which are widely used in SOFCs, and newly developed BaZr0.375Yb0.125Co0.5O3-δ were sintered at 900°C to 1000°C. The electrochemical performance of the planar cell was investigated at 600°C under the conditions of a humid fuel gas (i.e., 3% H2O and 97% H2) and humid air (i.e., 3% H2O, 20% O2 and 77% N2). The active area of the planar cell was 0.785 cm2.

To evaluate the durability of each cell, continuous power generation tests were conducted at constant current. The durability test was conducted by generating power for 1000 hours at a constant current that resulted in a voltage of 0.85 V at the start of the test, and durability was evaluated by the rate of voltage drop per 1000 hours. As a result, the voltage reduction rate per 1000 hours for the cell using BaZr0.375Yb0.125Co0.5O3-δ as the air electrode was 7.3%/kh. The results clearly show that one of the most significant issues for practical use is the suppression of the rate of voltage drop. The resistance of the cell before and after the durability test were analyzed by electrochemical impedance method, and the ohmic resistance and electrode resistance increased. EPMA analysis of the cell cross section to investigate the cause of degradation revealed diffusion of Ni from the fuel electrode and Co from the air electrode in the electrolyte. Therefore, in order to further improve durability, there is a need to consider adding an anti-diffusion layer to prevent the diffusion of these elements and developing air electrode materials that do not contain Co.