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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Accelerating Parallel Applications in Cloud Platforms via Adaptive Time-Slice Control

Cloud platforms can provide flexible and cost-effective environments for parallel applications. However, the resource over-commitment issues, i.e., cloud providers often provide much more executable virtual CPUs than available physical CPUs, still impede the synchronization operations of parallel applications, causing severe performance degradation. Existing methods optimize parallel applications by promoting the priorities of involved VMs. They cannot fully explore the performance of parallel applications, because they ignore the time-slice requirements of different phases of parallel applications. Furthermore, non-parallel applications experience unsatisfied performance because of low scheduling priorities. Given empirical analysis on time-slices of virtual machines (VMs), we find that shortening time-slices can mitigate synchronization overhead which incurs during communication phases, while over-short time-slices cause frequent cache misses in computation phases. Accordingly, we propose an Adaptive Time-slice Control (ATC) mechanism. ATC first detects the phases of parallel applications based on lock latency or cache misses. Then, ATC shortens time-slices during communication phases and prolongs time-slices during computation phases for parallel applications, and sets a uniform time-slice for non-parallel applications. Finally, we evaluate ATC using seven well-known benchmarks with 25+ applications. Experiments show that ATC obtains 1.5-75x performance gain for running parallel applications than state-of-the-art solutions, with nearly unaffected impact on non-parallel applications.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

Metastability and Long-Term Degradation in CIGS Devices: Effect of Alkali Treatments, Back Contact and Emitter Layers

Thin-film solar cell technologies often suffer from metastable and long-term performance degradation, which may or may not be reversible. The presence of the transient or degradation issues pose challenges for energy-yield prediction in the field for these technologies. Cu(In,Ga)(S,Se) 2 solar cells are a promising thin-film technology, however, the underlying mechanisms of instability in these devices are not well understood. The most common mechanism of metastability in CIGS solar cells has been speculated to be the configuration changes of (VSe-VCu) divacancy complex. However, the role of metastability in light soaking behavior and the effect of alkali treatments and buffer layers is not understood. The goal of the current project is to understand the effect of alkali treatments and buffer materials on metastability and light soaking behavior and develop a device model to simulate experimental results. Input parameters are taken from literature or derived from first-principle calculations, and are fine-tuned through validation experiments.

14 SOLAR ENERGY↗
DOE OSTI2024

Assessment of Accelerated Stress Testing Data for Silicon Photovoltaics Using Tensor Decomposition Methods

In this work, we examine the use of high-order tensor decompositions to analyze degradation pathways emerging from accelerated stress testing of silicon photovoltaic (PV) modules. Matrix-based decompositions are powerful tools for studying two-dimensional data arrays and form the foundation of a host of classical data analysis techniques. Tensors are high-order extrapolations of matrices that are able to account for more parameter dimensions, and a variety of tensor decomposition methods have been developed that similarly seek to extend insights from matrix decompositions to higher dimensions. Applying and interpreting tensor decomposition methods to sequences of PV module image data, we seek to uncover and isolate different degradation modes occurring from accelerated stress testing procedures. Further, we consider the contributions of different modes to PV module performance degradations.

data analysis↗
DOE OSTI2021

Performance and Durability of Pure-Water-Fed Anion Exchange Membrane Electrolyzers Using Baseline Materials and Operation

Water electrolysis powered by renewable electricity produces green hydrogen and oxygen gas, which can be used for energy, fertilizer, and industrial applications and thus displace fossil fuels. Pure-water anion-exchange-membrane (AEM) electrolyzers in principle offer the advantages of commercialized proton-exchange-membrane systems (high current density, low cross over, output gas compression, etc.) while enabling the use of less-expensive steel components and nonprecious metal catalysts. AEM electrolyzer research and development, however, has been limited by the lack of broadly accessible materials that provide consistent cell performance, making it difficult to compare results across studies. Further, even when the same materials are used, different pretreatments and electrochemical analysis techniques can produce different results. Here, we report an AEM electrolyzer comprising commercially available catalysts, membrane, ionomer, and gas-diffusion layers operating near 1.9 V at 1 A cm –2 in pure water. After the initial break in, the performance degraded by 0.67 mV h –1 at 0.5 A cm –2 at 55 °C. We detail the key preparation, assembly, and operation techniques employed and show further performance improvements using advanced materials as a proof-of-concept for future AEM-electrolyzer development. Here, the data thus provide an easily reproducible and comparatively high-performance baseline that can be used by other laboratories to calibrate the performance of improved cell components, nonprecious metal oxygen evolution, and hydrogen evolution catalysts and learn how to mitigate degradation pathways.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

3D ion gyro-orbit heat load predictions for NSTX-U

Abstract High power tokamaks operate with divertor heat loads capable of destroying the plasma facing components (PFCs). High fidelity heat load predictions are necessary to ascertain the PFC state for design and during operation. Typical heat flux calculations are 2D, time invariant, and assume that power flows directly along the magnetic field lines (the optical approximation). These assumptions neglect the complex 3D geometries employed to protect the PFCs, the time varying nature of the plasma and PFC thermal state, and the helical trajectories of ions with finite Larmor radii (the gyro-orbit approximation). An integrated software framework, the heat flux engineering analysis toolkit (HEAT), was developed to generate time varying optical heat loads applied to real engineering computer aided design (CAD) (Looby et al 2022 Fusion Sci. Technol. 78 10–27). Recently, an ion-gyro orbit module has been added to HEAT. This module calculates the helical trajectories of ions as they gyrate about the magnetic field lines using kinetic theory macro-particles to accelerate the calculation. First, the new gyro-orbit module will be presented. Next, a comparison to existing research is performed. Finally, an analysis of the gyro-orbit heat loads for NSTX-U is presented for diverted discharges using the engineering CAD models utilized for PFC fabrication. Including these gyro-orbit effects can enhance the PFC performance by ‘smearing’ out the magnetic shadows associated with the castellated fish-scaled geometry. Simultaneously, the helical trajectories can degrade performance when they load narrow regions on edges and corners with high heat fluxes. Analysis of the trade-offs between these competing effects is included, and regions for further investigation are identified.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Analysis of Degradation and Electrochemical Behavior of Lithium–Oxygen Batteries under Lean Electrolyte Conditions

Lithium-oxygen batteries have garnered much attention in the past decades due to their high energy density and active material abundancy. Decreasing the electrolyte volume is critical to achieving a high energy density for practical applications. Recent works have demonstrated a serious performance limitation at lower electrolyte fillings. Here, in this work, we study specifically the difference between flooded and lean electrolyte lithium-oxygen batteries by systematically tracing the source of performance degradation. We find that the key contributor to the decrease in performance under lean electrolyte conditions stems from the lithium metal anode rather than the cathode. Solid electrolyte interphase (SEI) compositionally appears to be the same from X-ray photoelectron spectroscopy but the coverage is less uniform, and impedance is much higher under lean electrolyte conditions. Such an effect likely produced the observed poorer cycle performance at 10 μL cm -2 (similar to 28% cathode's pore volume filled) vs 100 μL cm -2 (278% of cathode's pore volume) at a capacity of 1.0 mAh cm -2 (0.1 mAh cm -2 ) using an electrolyte composition of 1 M LiTFSI in TEGDME.

Córdoba, Daniel [Argonne National Laboratory (ANL)↗
DOE OSTI2024

A Tandem Electrolysis Process for Multi-Carbon Chemical Production from Carbon Dioxide (Final Technical Report)

a two-step CO 2 electroreduction process for selective production of acetate and ethylene was successfully developed at the kW-scale. The CO 2 and CO electrolyzers were first investigated individually on the Watt-scale to achieve high current densities and more durable operation by using a reinforced GDL. High CO 2 conversion was obtained in the first CO 2 electrolyzer to produce a CO-dominant gas stream with minimal CO 2 , and highly pure acetate stream was produced in the second CO electrolyzer by using NiFe anode, which promoted alcohol oxidation to carboxylates. The two-step process operated stably for 200 h with acetate and ethylene as the major C 2+ products. Degradation mechanism study revealed that the flooding and the salt formation in the GDL is likely the biggest contributor to the performance degradation for both CO 2 and CO electrolyzers. A 1,000 cm 2 CO electrolyzer stack was then designed, fabricated, and operated up to a total current of 300 A along with a 500 cm 2 CO 2 electrolyzer stack which was operated up to a total current of 100 A. The CO electrolyzer stack demonstrated good stability at 300 A for at least 125 h at a carbon selectivity >96%. The impact of CO 2 , O 2 , N 2 , SO x , and NO x gas impurities on the CO electrolyzer stack was studied and a relatively high resistance to these contaminants was demonstrated. Electroreduction of CO 2 into acetic acid was also demonstrated to be environmentally favorable when compared to the traditional production of acetic acid when powered by renewable electricity. Additionally, electricity cost was identified as the primary source of cost sensitivity indicating substantial economic improvements could be achieved by continuing to drive down the cost of renewable electricity. Overall, the presented approach demonstrates the feasibility of the two-step electrochemical CO 2 reduction process for the effective production of C 2+ products at the kW-scale which should inspire future scaling efforts accelerating commercialization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Focused Helium Ion Beam for Direct Patterning of Monolayer MoS 2 Nanoribbon Field Effect Devices

The helium ion microscope (HIM) focused ion beam (FIB) has emerged as a powerful tool to directly pattern nanostructures below 10 nm due to its high-resolution capabilities and the inert nature of the ion source. These attributes make HIM FIB particularly interesting for patterning 2D materials such as transition metal dichalcogenides (TMDs) to investigate transport phenomena at the nanoscale. Reported here is the fabrication of MoS 2 nanoribbon devices using HIM FIB-induced etching (FIBIE) with XeF 2 , allowing for reduced ion dose compared to direct sputtering. While patterning is efficacious, the devices exhibit performance degradation with decreasing nanoribbon width due to damage up to 150 nm beyond the patterned edge. Incorporating an hBN encapsulation improves device performance by one order of magnitude, although the lateral extent of damage remains unchanged. The spatial distribution of damage is shown to be determined by the forward- and backscattered ions and electrons, while the hBN encapsulation layer substantially reduces damage from XeF 2 interactions in unexposed regions. Raman and photoluminescence (PL) measurements corroborate these findings, while ion/solid interaction simulations further elucidate the resolution limits imposed by substrate interactions. In conclusion, this work provides critical insights and a practical pathway for utilizing HIM FIBIE in 2D TMD functional device patterning.

MoS 2↗
DOE OSTI2026

Holistic energy analysis method for thermal management architectures of data centers

Modern high-performance computing (HPC) data centers (DCs), particularly those supporting energy-intensive artificial intelligence (AI) workloads, face escalating thermal management challenges that degrade performance through thermal throttling and drive up cooling power consumption and operational costs. To address this challenge, many have developed a wide variety of thermal management solutions (single-phase, two-phase, direct, indirect, hybrid, and more) which attempt to cool HPC DCs effectively while attempting to minimize overall system power consumption. However, the analysis of these solutions and methods to effectively compare one with another is lacking. Overall power usage effectiveness (PUE) and total-power usage effectiveness (TUE) provide a metric to quantify power consumption but fail to identify components in the system which require further optimization. To address this, we propose a holistic analytical framework – the waterfall diagram (WFD) – which leverages a waterfall chart methodology, offering a comprehensive visualization of both the thermal management system loop and heat flow pathways from individual server components to the outdoor ambient. Use of the WFD enables graphical estimations of power efficiency and cooling performance across each component of a DC cooling system and complements Sankey-style energy flow visualizations by additionally resolving stage-wise temperature changes and incremental TUE contributions. The framework is used in conjunction with simulation-based approaches, to conduct a detailed pressure drop and flow distribution analysis aimed at identifying the optimal coolant distribution architecture for a single-phase direct-to-chip water-cooled DC, which serves as the baseline for subsequent WFD analysis. Among the evaluated architectures, the 3 U modular coolant distribution architecture is found to demonstrate the best performance, considering minimal pressure drop and uniform flow distribution. In addition, TUE is calculated for each cooling loop component based on its associated pressure drop and corresponding pumping power, which are integrated into the WFD. This correlation between TUE and local temperature offers immediate insight into the power efficiency and thermal performance contributions of individual components, facilitating further development and optimization. Examples of WFD applications are presented under varying thermal loads and ambient conditions, demonstrating reasonable cooling strategies. Notably, the 3 U modular architecture maintains a consistent chip case temperature of 85°C, achieving a TUE of 1.016 at ambient temperature of 47°C, and a TUE of 1.026 at ambient temperature of 52°C. The WFD methodology provides an efficient, holistic, and streamlined framework for DC thermal management architecture assessment and enables design optimization which is important for addressing the thermal-fluidic energy challenges of current and next-generation DCs.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Flexible, Multipurpose Laboratory Advances Building and Thermal Energy Systems: Expanding Evaluation and Development of Grid-Interactive Buildings

Robust hardware and controls are necessary to ensure results match their intent before they can be used broadly. However, this often requires multiple field experiments in a variety of climate zones. In the field, it is more difficult to obtain information on other important factors, such as thermal, grid, and occupant interaction. Gaps also exist in understanding the performance degradation and life cycle of thermal energy systems as they relate to buildings. There is a lack of robust, high-quality performance data for projects at scale; this data can be expensive to produce and often remain proprietary.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2026

Atomic- and Molecular-Scale Interphase Engineering for High-Performance Solid-State Batteries

Solid-state batteries (SSBs) promise a decisive advance beyond conventional Li-ion systems, yet their development remains constrained by persistent solid–solid interfacial instabilities that degrade performance and durability. Interfaces between solid electrolytes and both cathodes and Li metal often exhibit poor wettability, limited physical contact, and high charge–transfer resistance, leading to chemical decomposition, mechanical failure, and impedance growth. Overcoming these limitations requires interphase engineering with atomic-scale precision—capabilities that conventional coating methods cannot reliably deliver. Atomic layer deposition (ALD) and molecular layer deposition (MLD) uniquely meet this need by enabling ultrathin, conformal, and composition-tunable films that stabilize reactive surfaces, suppress parasitic reactions, and regulate Li-metal morphology. Importantly, this Perspective highlights ALD/MLD systems that have already demonstrated effectiveness in liquid-electrolyte cells and discusses how these validated strategies can be deliberately translated to solid-state architectures. By grounding future directions in experimentally proven concepts rather than speculative hypotheses, we outline how atomic- and molecular-scale design principles can accelerate the development of robust, high-performance SSB technologies.

atomic and molecular layer deposition↗
DOE OSTI2026

Understanding the Performance Gap between Polycrystalline and Single-Crystal Nickel-Rich Layered Oxide Cathodes

Singe-crystal (SC) nickel-rich layered oxide cathodes, composed of boundary-free particles with high tap density, offer significant advantages in volumetric energy density and mechanical strength compared with polycrystalline (PC) cathode materials. However, as the nickel content increases (≥80%), SC Ni-rich cathodes often suffer from faster performance degradation than PC cathodes of the same composition, and the underlying causes of this discrepancy remain poorly understood. Herein, we reveal the distinct Ni redox behaviors that govern the electrochemical performance of SC and PC Ni-rich cathodes using multiscale and operando characterization techniques. Our results indicate that the increasingly heterogeneous Ni oxidation process in SC cathodes leads to the additional irreversible oxygen redox activity that deteriorates both the mechanical and chemical structures. In contrast, PC cathodes, despite with more pronounced surface reconstruction, exhibit greater chemomechanical stability due to homogeneous redox reactions during charging. Consequently, we find that bulk degradation, more than surface reactions, ultimately leads to fast capacity decay of SC Ni-rich cathodes during cycling. In conclusion, this work offers a comprehensive view on the impact of Ni redox evolutions on the chemomechanical stability in Ni-rich layered oxide cathodes, providing new insights into the longstanding performance gap between SC and PC cathodes, and guiding the rational design of Ni-rich cathode architectures.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Trends in Field and Laboratory Performance of Photovoltaic Modules and Materials

This DuraMAT project intends to identify bill of materials (BOM) and/or process control measures for photovoltaic modules with representative failure modes as informed by accelerated and field tests to guide next steps in module and material design. We have begun work to identify correlation between module field performance and accelerated testing results by cross-comparing a module database of accelerated test results with a module database of fielded systems. We have identified fielded systems with degraded performance, and intend to compare this to the results observed in certification and qualification testing. We also intend to apply lessons and observations from accelerated tests to the field, where it may be possible to mitigate or avoid degradation in the field.

DuraMAT↗
DOE OSTI2025

Constructing Highly Durable Fuel Cell Catalysts Through Integrating Graphitic Shell‐Protected Composite Carbon Support with Gaseous Co Deposition‐Driven PtCo Intermetallics

Metal dissolution, nanoparticle agglomeration, and carbon support corrosion cause significant performance degradation of current PtCo catalysts under acidic and oxidative oxygen reduction reaction. Here, in this study, an integrated strategy is presented to design high-performance Pt 3 Co intermetallic catalysts by regulating gaseous Co deposition-driven diffusion into Pt nanoparticles supported on a composite carbon. The composite carbon is derived from ZIF-8/polyaniline, consisting of a high-surface-area (HSC) core and a protective graphitic shell (GS), which is employed to design 40 wt.% Pt/HSC@GS catalyst. The corresponding membrane electrode assemblies (MEAs) can maintain 1.09 A cm −2 at 0.7 V (20. 7% loss) after 10 000 cycles (1.0–1.5 V for carbon stability) and 1.15 A cm −2 (16.1% loss) after 150 000 cycles (0.60–0.95 V for catalyst stability). A ordered Pt 3 Co intermetallic is synthesized via a gaseous Co-deposition process, which yields a homogeneous Co-rich layer onto the Pt nanoparticles on the composite support, thereby facilitating Co diffusion into Pt crystal during subsequent ordering annealing to form the ordered intermetallic structure. This gaseous deposition leads to a thin carbon layer on PtCo nanoparticles, inhibiting particle growth during the annealing and mitigating Co dissolution under dynamic electrochemical conditions. The PtCo catalyst achieves impressive MEA performance and long-term durability (1.45 A cm −2 at 0.7 V after 120 000 cycles) under heavy-duty conditions.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2020

Charge collection and electrical characterization of neutron irradiated silicon pad detectors for the CMS High Granularity Calorimeter

The replacement of the existing endcap calorimeter in the Compact Muon Solenoid (CMS) detector for the high-luminosity LHC (HL-LHC), scheduled for 2027, will be a high granularity calorimeter. It will provide detailed position, energy, and timing information on electromagnetic and hadronic showers in the immense pileup of the HL-LHC. The High Granularity Calorimeter (HGCAL) will use 120-, 200-, and 300-$\mu\textrm{m}$ thick silicon (Si) pad sensors as the main active material and will sustain 1-MeV neutron equivalent fluences up to about $10^{16}~\textrm{n}_\textrm{eq}\textrm{cm}^{-2}$. In order to address the performance degradation of the Si detectors caused by the intense radiation environment, irradiation campaigns of test diode samples from 8-inch and 6-inch wafers were performed in two reactors. Characterization of the electrical and charge collection properties after irradiation involved both bulk polarities for the three sensor thicknesses. Since the Si sensors will be operated at -30 $^\circ$C to reduce increasing bulk leakage current with fluence, the charge collection investigation of 30 irradiated samples was carried out with the infrared-TCT setup at -30 $^\circ$C. TCAD simulation results at the lower fluences are in close agreement with the experimental results and provide predictions of sensor performance for the lower fluence regions not covered by the experimental study. All investigated sensors display 60$\%$ or higher charge collection efficiency at their respective highest lifetime fluences when operated at 800 V, and display above 90$\%$ at the lowest fluence, at 600 V. The collected charge close to the fluence of $10^{16}~\textrm{n}_\textrm{eq}\textrm{cm}^{-2}$ exceeds 1 fC at voltages beyond 800 V.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2023

Using simulation to study solid oxide cell degradation

Slides of the presentation given by Harry Abernathy from the National Energy Technology Laboratory at the 2023 International Conference and Expo on Advanced Ceramics and Composites. The presentation was an overview of NETL's solid oxide cell performance degradation modeling, including a demonstration of the impact of microstructural analysis methods on the resulting degradation simulations.

Abernathy, Harry↗
DOE OSTI2025

The Effect of Operational Temperature on the Performance and Durability of Solid Oxide Fuel Cells and Solid Oxide Electrolysis Cells

Solid oxide fuel cells (SOFC) and solid oxide electrolysis cells (SOEC) have received great interest due to their highly effective reversibility as power generation and H2 production system without releasing any greenhouse gases into environment. The LSCF electrode exhibits a higher structural and performance stability under both SOFC and SOEC operation due to its mixed ionic and electronic conductivity, and there is no immediate delamination taking place during the initial several hundred hours operation. However, the LSCF based air electrode still presents significant performance degradation (with the increased resistance) over the prolonged operation, such as over 1000 hours of operation under SOFC and SOEC. The influence factors for the cell’s performance and stability need to be optimized to improve the power generation for SOFC and H2 production for SOEC. The effects of operational temperature on the performance and durability for both SOFC and SOEC are electrochemical operation dependent. The performance and performance durability for the first 1500h were currently studied under optimized operational temperature for reversible SOFC/SOEC.

Fan, Yueying [NETL Site Support Contractor, Nation↗
DOE OSTI2021

Performance of DSRC V2V Communication Networks in an Autonomous Semi-Truck Platoon Application

Autonomy for multiple trucks to drive in a fixedheadway platoon formation is achieved by adding precision GPS and V2V communications to a conventional adaptive cruise control (ACC) system. The performance of the Cooperative ACC (CACC) system depends heavily on the reliability of the underlying V2V communications network. Using data recorded on precision-instrumented trucks at both ACM and NCAT test tracks, we provide an understanding of various effects on V2V network performance: Occlusions - non-line-of-sight (NLOS) between the Tx and Rx antenna may cause network signal loss. Rain - water droplets in the air may cause network signal degradation. Antenna position - antennas at higher elevation may have less ground clutter to deal with. RF interference - interference may cause network packet loss. GPS outage - outages caused by tree cover, tunnels, etc. may result in degraded performance. Road curvature - curves may affect antenna diversity. Road grade - antenna may have limited vertical coverage. Our results, which include multiple plots and graphs and their analysis, build on those reported by others and could be of interest to researchers, practitioners, and end-users in the broader autonomous-connected vehicle community.

V2V communications, GPS, truck platoon, semi-auton↗