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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Toward Superb Perovskite Oxide Electrocatalysts: Engineering of Coupled Nanocomposites

Abstract A significant issue that bedeviled the commercialization of renewable energy technologies, ranging from low‐temperature water electrolyzers to high‐temperature solid oxide cells, is the lack of high‐performance catalysts. Among various candidates that could tackle such a challenge, perovskite oxides are rising‐star materials because of their unique structural and compositional flexibility. However, single‐phase perovskite oxides are challenging to satisfy all the requirements of electrocatalysts concurrently for practical applications, such as high catalytic activity, excellent stability, good ionic and electronic conductivities, and superior chemical/thermo‐mechanical robustness. Impressively, perovskite oxides with coupled nanocomposites are emerging as a novel form offering multifunctionality due to their intrinsic features, including infinite interfaces with solid interaction, tunable compositions, flexible configurations, and maximum synergistic effects between assorted components. Considering this new configuration has attracted great attention owing to its promising performances in various energy‐related applications, this review timely summarizes the leading‐edge development of perovskite oxide‐based coupled nanocomposites. Their state‐of‐art synthetic strategies are surveyed and highlighted, their unique structural advantages are highlighted and illustrated through the typical oxygen reduction reaction and oxygen evolution reactions in both high and low‐temperature applications. Opinions on the current critical scientific issues and opportunities in this burgeoning research field are all provided.

08 HYDROGEN↗
DOE OSTI2025

Design of a robot-automated flat plate/reflection geometry x-ray diffraction setup for accelerated materials discovery and structural screening

Here, we report the design, construction, and automation of a flat plate sample loading, alignment, and data acquisition system for X-ray diffraction measurements in reflection geometry implemented at the Stanford Synchrotron Radiation Lightsource. The system is built onto a single platform, enabling facile transferability, and is compartmentalized into sample storage, sample transfer, and sample position/alignment segments. The core feature of this system is a six-axis robotic arm that offers a large range of highly reproducible and programable movements. The degrees of freedom of the robot arm enable adaptability in which movements can be modified to fit various beamline environments and sample configurations. Samples are housed on 3D printed sample mounts, which are arranged onto a 6 × 2 array of sample cassettes capable of holding 7 samples. Using sample mounts designed for solid oxide electrolysis button cells (SOECs), the maximum tray capacity is 84 samples, which can be aligned and run in ~ 24 hours with long exposure scans. The sample array is additionally capable of accommodating a range of sample sizes and geometries due to the rapid 3D printed fabrication. The components of the setup will be described in detail and performance will be demonstrated with a set of representative SOEC and XRD standard samples. Opportunities for future developments and integration with the automated setup are summarized.

08 HYDROGEN↗
DOE OSTI2022

Tuning Surface Acidity of Mixed Conducting Electrodes: Recovery of Si‐Induced Degradation of Oxygen Exchange Rate and Area Specific Resistance

Abstract Metal oxides are an important class of functional materials, and for many applications, ranging from solid oxide fuel/electrolysis cells, oxygen permeation membranes, and oxygen storage materials to gas sensors (semiconducting and electrolytic) and catalysts, the interaction between the surface and oxygen in the gas phase is central. Ubiquitous Si‐impurities are known to impede this interaction, commonly attributed to the formation of glassy blocking layers on the surface. Here, the surface oxygen exchange coefficient ( k chem ) is examined for Pr 0.1 Ce 0.9 O 2‐δ (PCO), a model mixed ionic electronic conductor, via electrical conductivity relaxation measurements, and the area‐specific resistance (ASR) by electrochemical impedance spectroscopy. It is demonstrated that even low silica levels, introduced by infiltration, depress k chem by a factor 4000, while the ASR increases 40‐fold and we attribute this to its acidity relative to that of PCO. The ability to fully regenerate the poisoned surface by the subsequent addition of basic Ca‐ or Li‐species is further shown. This ability to not only recover Si‐poisoned surfaces by tuning the relative surface acidity of an oxide surface, but subsequently outperform the pre‐poisoned response, promises to extend the operating life of materials and devices for which the catalytic oxygen/solid interface reaction is central.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

Protonic Ceramics for Energy Storage & Electricity Generation with Ammonia (Final Report)

The commercial product resulting from this R&D project will enable cost-effective synthesis of the Carbon Neutral Liquid Fuel (CNLF) ammonia, a common chemical, at a small scale for energy and industrial applications using only intermittent renewable energy, water, and air as feedstocks. These products are also capable of producing electrical energy from the CNLF in a fuel cell mode of operation. Thus, the eventual commercial product enables both single direction production of either CLNF or electricity, or alternatively functions as a fully reversible, self-contained energy storage device. The renewed interest in developing electrolysis systems is driven, in part, by the burgeoning renewable, solar, and wind industries and the need for an energy conversion and storage technology that can convert intermittent solar and wind energy into the production of hydrogen. Electrolysis systems integrated into both distributed and central renewable power plants would utilize solar and wind energy as their primary power source to produce renewably generated hydrogen for local energy storage or chemical feedstock purposes. Ammonia is an excellent surrogate for hydrogen transportation. NH3 presents an attractive alternative to hydrogen as a working fluid in reversible devices towards a sustainable green energy-oriented future. Ammonia can be easily liquefied at room temperature at about 8 bar or at -33°C at ambient pressure. In contrast, the liquefaction temperature of hydrogen is -253°C at ambient pressure. NH3 has a significantly higher volumetric energy density (12.7 MJ/L) than compressed hydrogen (4.5 MJ/L at ~70 MPa) or liquefied hydrogen (8.5 MJ/L). Additionally, ammonia is a widely used raw material for agriculture fertilizer and thus has well-established storage, transport, and handling processes (about 180 million tons of ammonia are produced annually). Techno-economic analysis suggests ammonia is the least expensive fuel among hydrogen, gasoline, natural gas, liquefied petroleum gas, and methanol.

08 HYDROGEN↗
DOE OSTI2021

Moderate temperature sintering of BaZr 0.8 Y 0.2 O 3-δ protonic ceramics by A novel cold sintering pretreatment

The state-of-the-art protonic ceramic conductor BaZr 0.8 Y 0.2 O 3-δ (BZY20) requires an extremely high sintering temperature (≥1700 °C) to achieve the desired relative density and microstructure necessary to function as a proton conducting electrolyte. In this work, we developed a cold sintering pretreatment assisted moderate-temperature sintering method for the fabrication of high-quality pure BZY20 pellets. BZY20 pellets with high relative density of ~94% were fabricated with a final sintering temperature of 1500 °C (200 °C lower than the traditional sintering temperature). A comparison with BZY20 control samples indicated that the proper amount of BaCO 3 introduced on the BZY20 particle surface and the high green density achieved by cold sintering pretreatment were the main drivers for lowering the sintering temperature. The electrical conductivity measurement by electrochemical impedance spectroscopy showed that the as-prepared BZY20 pellets have a proton conductivity comparable to the state-of-the-art values. The cold sintering pretreatment outlined in this work has the potential to lower the sintering temperatures for similar types of protonic ceramic materials under consideration for a wide range of energy conversion and storage applications.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Evolution of the structure and chemical composition of the interface between multi-component silicate glasses and yttria-stabilized zirconia after 40,000 h exposure in air at 800 °C

The chemical and structural stability of two commercial multicomponent silicate glasses (SCN and G6) in contact with yttria-stabilized zirconia (YSZ) was investigated after exposure times of up to 40,000 h in air at 800 °C. With exposure time, interfacial layers develop at the SCN-YSZ and G6-YSZ interfaces, which were characterized in detail using both quantitative chemical analysis and atomic-resolution imaging. At the SCN-YSZ interface, a Ca-Ba-Si-O reaction phase was found to grow by diffusion control. In G6-YSZ, Raman spectroscopy and electron microscopy revealed a disorganized interfacial reaction later between G6 and YSZ, and the occurrence of cubic to tetragonal to monoclinic phase transformations in YSZ. Finally, this microstructural evolution is discussed in terms of devitrification resistance of glass and diffusion processes at interfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A Facile, One-Step Synthesis for Core–Shell Perovskite Materials via Molten Salt

Core–shell La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3 (LSCF)–La 0.8 Sr 0.2 MnO 3 (LSM) heterostructure crystalline materials have been synthesized in a simple, one-step feeding method via a KNO 3 molten salt solvent. Two-phase perovskite composites can be synthesized in times as short as 10 minutes and is demonstrated for the first time in a molten salt. Further, a combination of X-ray diffraction and S/TEM energy dispersive X-ray spectroscopy has been utilized to confirm the formation of an LSM shell on LSCF cores in all samples when adjusting dwell time, core size, weight ratio between core and shell precursors, and weight ratio of powder to salt. Specifically, decreasing the LSCF core size increases core–shell yield. Smaller cores introduce a greater density of facets on the crystal surface and provide more favorable sites for LSM heterogeneous nucleation.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Improving Ni-Based SOFC Anode Resilience and Durability through Secondary Phase Formation

The project used a multi-disciplinary approach to test test if 2° materials, added to traditional cermet components, enhanced SOFC mechanical strength, anode resilience and durability when subjected to electrochemical and environmental redox cycling. Findings from fracture testing, electrochemical studies and operando Raman spectroscopy measurements demonstrated that aluminum titanate (Al 2 TiO 5 or ALT) mechanically mixed with NiO-YSZ cermets confers superior mechanical strength and slower degradation rates under polarization. No deleterious effects from ALT in conversion efficiency were observed. Specific accomplishments included the following: (1) Refined methods used to fabricate ALT enhanced anodes into bi-layer anode supports to achieve high power densities; (2) Compared the effects of adding ALT mechanically to Ni-YSZ powders prior to anode fabrication with adding ALT through infiltration and co-infiltration of YSZ scaffolds; (3) Tested the resilience of these novel materials to electrochemical and environmental redox cycling and thermal stresses commonly encountered in functioning SOFCs; and (4) Characterized the ability of ALT to improve the carbon tolerance of Ni-YSZ anodes operating with dry methane.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2021

Tuning Surface Stoichiometry of SOFC Electrodes at the Molecular and Nano-scale for Enhanced Performance and Durability

This project achieved the following objectives. Different cation segregation behaviors of different common SOFC cathodes, including La 0.6 Sr 0.4 Co0.2Fe 0.8 O 3-δ (LSCF), Sr 0.5 Sm 0.5 O 3-δ (SSC), and PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O5 +δ (PBSCF), were determined. We showed how oxygen partial pressure and gas impurities impact the stability of SOFC cathodes. We developed atomic layer deposition (ALD) coating techniques for electrodes and showed that by introducing different elements and different ALD oxidizers, electrode surface chemistry can be altered, resulting in enhanced oxygen reduction kinetics. In addition, we developed solution infiltration technique to enhance performance and durability of electrodes. Different infiltrates as well as different thermal treatment processes were screened to identify the optimal surface modification process that yields both low impedance and high durability. The modified cathode shows excellent stability and has a low area specific resistance (ASR) of only 0.2 Ωcm 2 at 600 °C after over 2000 hours of operation. Further, we developed ceramic anodes, SrFe(Co,Mo)O 3 (SFCM) and SrFe(Ni,Mo)O 3 (SFNM), and enhanced anode oxidation kinetics by solution infiltration or in situ catalyst exsolution from the ceramic anode surface. The modified anodes showed improved performance in full SOFCs, and the optimized anode modification shows high stability for over 400 hours at 550 °C. Moreover, the modified anode also demonstrates high durability in methane. This work provides fundamental understanding of electrode surface chemistry and demonstrates a simple, facile, cost-effective approach to enhance catalytic activity and durability of SOFC electrodes.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2025

Hybrid SOFC-Turbogenerator for Aircraft (Final Scientific/Technical Report)

The following paragraphs provide a high-level summary of the work performed during Phases I and II of this contract. Note that the order deviates from the WBS in places to better reflect the actual sequence of activities and the connections between them. Corresponding task numbers in the WBS are provided in parentheses after the task titles. There are a total of thirteen (13) tasks.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Influence of Heterointerfaces on the Kinetics of Oxygen Surface Exchange on Epitaxial La 1.85 Sr 0.15 CuO 4 Thin Films

Considerable attention has been directed to understanding the influence of heterointerfaces between Ruddlesden–Popper (RP) phases and ABO 3 perovskites on the kinetics of oxygen electrocatalysis at elevated temperatures. Here, we report the effect of heterointerfaces on the oxygen surface exchange kinetics by employing heteroepitaxial oxide thin films formed by decorating LaNiO 3 (LNO) on La 1.85 Sr 0.15 CuO 4 (LSCO) thin films. Regardless of LNO decoration, tensile in-plane strain on LSCO films does not change. The oxygen surface exchange coefficients (kchem) of LSCO films extracted from electrical conductivity relaxation curves significantly increase with partial decorations of LNO, whereas full LNO coverage leads to the reduction in the kchem of LSCO films. The activation energy for oxygen exchange in LSCO films significantly decreases with partial LNO decorations in contrast with the full coverage of LNO. Optical spectroscopy reveals the increased oxygen vacancies in the partially covered LSCO films relative to the undecorated LSCO film. We attribute the enhanced oxygen surface exchange kinetics of LSCO to the increased oxygen vacancies by creating the heterointerface between LSCO and LNO.

25 ENERGY STORAGE↗
DOE OSTI2025

High Power Density, Carbon Neutral Electrical Power Generation for Air Vehicles

The synergistic integration of a Solid Oxide Fuel Cell-Combustor (SOFC-C) with a turbogenerator (TG) will provide a very high fuel-to-electricity conversion efficiency while maintaining high power-to-weight ratio during high-altitude flight. The proposed SOFC-C-TG power generation technology exceeds the REEACH technical performance targets (TPT). This unique concept addresses many of the challenges faced in all electric propulsion-based aviation. The system has high part-load efficiency (more than 65% lower heating value (LHV)) during long cruise times, load following capability, high-power capacity at high altitudes adapting to low temperatures and pressures, rapid startup time of less than 30 minutes (proven with current SOFC technology), high power density (more than 3.2 kW/kg), efficient thermal management, and a foundation for a compact, efficient electrical storage and power generation system (ESPG). The SOFC-C concept achieves the technology targets by reducing the complexity of traditional fuel cell-gas turbine hybrid systems (FC-GT). The SOFC-C does not require heat exchangers and dramatically reduces the balance of plant increasing power density and performance in efficiency. The reduction in mass through elimination of heat exchangers, external reformer, and other components dramatically decreases the overall thermal dampening of the system which enables rapid startup and load following capability. Direct control of the cathode inlet temperature of the SOFC-C enables rapid warm-up of the SOFC tubes with the ability to reach operating temperature and full power in less than 30 minutes.

03 NATURAL GAS↗