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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Bilayer hybrid graphite anodes via freeze tape casting for extreme fast charging applications

Extreme fast charging (XFC) of lithium-ion batteries is critical for continuous market adoption of electric vehicles. However, mass transport limitations and sluggish kinetics lead to lithium plating in graphite anodes under fast charging conditions. One approach to address the mass transport limitation in graphite is to design low-tortuosity electrodes to enhance ionic transport. In this study, a bilayer hybrid structured electrode with directionally aligned channels was developed via freeze tape casting, which enables faster lithium ion diffusion through the graphite electrode. A scalable roll-to-roll process was designed in which slurry can be cast on any substrates for simple processing. Additionally, electrochemical impedance spectroscopy measurements indicated that the bilayer hybrid coating had both low tortuosity and short diffusion pathways, enabling XFC charging. Rate testing for the bilayer hybrid electrode indicated superior performance over the other coatings, exhibiting a ~20% improvement in the charge capacity compared with the conventional coating at 5C and 10 min total charging time. The bilayer hybrid electrode also demonstrated a 10% improvement in capacity retention compared with the conventional electrode after 1000 cycles at XFC conditions. This study demonstrates freeze tape casting as a scalable way to fabricate low-tortuosity electrodes for XFC applications.

25 ENERGY STORAGE↗
DOE OSTI2026

From atomistic models to machine learning: Predictive design of nanocarbons under extreme conditions

The formation of technologically valuable nanocarbon structures under extreme conditions, such as those produced during high-explosive detonations, remains poorly understood but holds significant potential for the development of controlled synthesis pathways. While detonation shockwaves provide the high-pressure, high-temperature environment required for nanodiamond formation, subsequent cooling and decompression dictate whether the diamond phase is preserved or transformed into other nanocarbon structures. Here, in this study, we employ GPU-accelerated reactive molecular dynamics (ReaxFF) simulations to investigate the graphitization and structural remodeling of detonation nanodiamond under nonlinear quench and pressure-release trajectories. We further investigate how the initial nanodiamond morphology; cuboctahedral, octahedral, or hexagonal prism influences the resulting transformation products. Evolution of nanostructure, allotrope (via simulated x-ray diffraction), carbon hybridization, and ring statistics are tracked during a two-stage quench from 5000 K to 60 GPa. Rapid cooling combined with slow decompression optimizes cubic diamond retention, whereas slow cooling with rapid pressure release promotes surface-to-core graphitization, producing concentric sp 2 -hybridized layers and hollowed inner shells. Octahedral nanodiamonds evolve into carbon nano-onions, initially forming bucky diamonds that progressively transform into fully sp 2 -hybridized structures, while hexagonal prisms preferentially form parallel-stacked graphite layers resembling carbon dots. Transient hexagonal diamond (lonsdaleite) emerges as an interfacial phase, suggesting potential reversibility in the shock-induced graphite-to-diamond transformation pathway transformation route. To extend predictive capabilities, we trained machine learning (ML) regressors on over 10 5 node-hours of molecular dynamics (MD) trajectories. A multilayer perceptron (MLP) model reliably predicts the number of graphitized layers from temperature–pressure trajectories with a coefficient of determination (R 2 ) exceeding 0.90. This high predictive fidelity enables efficient, high-throughput mapping of the synthesis parameter space for optimized graphitization outcomes. Collectively, morphological control combined with optimized quench–decompression conditions promote the selective synthesis of nanocarbon allotropes. This work establishes a data-driven framework for the rational, a priori design of carbon nanomaterials for applications in energy storage, sensing, and biomedicine.

Detonation nanodiamond remodeling↗
DOE OSTI2020

Electrode scale and electrolyte transport effects on extreme fast charging of lithium-ion cells

A combination of cell testing and electrochemical modeling is used to investigate extreme fast charging (XFC) performance for cells with a low loading of 1.5 mAh.cm -2 and moderate loading of 2.5 mAh.cm -2 . Cells with a low loading of 1.5 mAh.cm -2 withstand XFC performance remarkably well even up to 9C CC charging with high charge acceptance and very little lithium plating. For a moderate loading of 2.5 mAh.cm -2 , the 6C CC charge capacity is poor with significant amounts of lithium plating. Insufficient electrolyte transport properties are shown to be a major limitation for XFC performance of moderate and high loading cells. Charging at elevated temperature is shown to be an effective strategy for moderate loading cells enabling good 10-minute charge acceptance and mitigating lithium plating. Finally, the electrochemical model is used to investigate strategies for enabling 4-6C CC charging for cells with a loading of 3-4 mAh.cm -2 . A combination of elevated temperature, reduced tortuosity, and electrolytes with improved transport are likely needed to enable XFC for high energy density cells.

25 ENERGY STORAGE↗
DOE OSTI2024

Stochastic economic dispatch of wind power under uncertainty using clustering-based extreme scenarios

Operation of power systems with high penetrations of renewable energy sources requires tools for robust decision making under uncertainty. Stochastic economic dispatch and stochastic unit commitment are effective techniques for planning and operation under uncertainty, whose effectiveness depends on the cardinality and quality of the scenario set. Here, this article proposes a machine learning method using -means clustering for capturing relevant physical information from a large population of analog scenarios. Extreme scenario samples drawn from the clusters are used in a two-stage stochastic economic dispatch computation. The effectiveness of the proposed approach is assessed on a synthetic 200-bus system with a geographic footprint over Illinois, USA for four months from each season of WIND Toolkit data. The combination of -means clustering with importance sampling is shown to reduce the total operational cost by over 43% compared to sampling from populations based on heuristic clustering-based methods. Additionally, the variability in the mean cost is about 56% lower than the variability using Monte Carlo sampling. Moreover, the operational cost with the presented approach is shown to be close to the cost calculated based on a hindsight exact wind profile, signifying a highly accurate quantification of wind uncertainty by the presented -means clustering based sampling method.

17 WIND ENERGY↗
DOE OSTI2022

Extreme fast charge aging: Correlation between electrode scale and heterogeneous degradation in Ni-rich layered cathodes

Extreme fast charging (XFC) is a key requirement for the adoption of battery-based electric vehicles by the transportation sector. However, XFC has been shown to accelerate degradation, causing the capacity, life, and safety of batteries to deteriorate. There are no systematic studies in the open literature regarding aging modes in Ni-rich Li y Ni 0.a Mn 0.b Co 0.c O 2 (NMCabc) cathodes caused by fast charging. Herein, we report the effects of cathode composition and electrode loading in pouch cells containing NMC532, 622 and 811 paired with graphite and cycled under XFC conditions. The relative anisotropic volume change in the unit cell increases with Ni content in low-loading cells, while it levels up for all three NMC cathodes in high-loading cells because of substantial Li plating. The amounts of lithium plating and heterogeneity on the anode, determined by crystallographic phase quantification, were found to be correlated with electrode loading and cathode heterogeneity. The concentrations of the transition metals deposited on the anodes depend on NMCabc composition in a complex way. More particle cracking and surface degradation was found in NMC811. Here, the findings in this work provide a new understanding of the failure mechanisms and their practical implications for compositional tuning of future high-Ni NMCabc cathode materials during fast charging.

25 ENERGY STORAGE↗
DOE OSTI2022

Developing extreme fast charge battery protocols – A review spanning materials to systems

Extreme fast charging (XFC) has become a focal research point in the lithium-battery community over the last several years. As adoption of electric vehicles increases, fast charging has become a key driver in enhancing consumer recharge experience. Recently, the research community has made significant improvements in developing charge protocols to support XFC. New charge protocol designs derived using a combination of advanced, physically derived models, and electrochemical and secondary characterization methods, increase charge acceptance and decrease aging. By coordinating these methods and modifying protocols to account for different material constraints, including lithium plating and cathode particle degradation, novel charge protocols have increased the energy accepted during charging by over 25% in 10 min and increased the charge acceptance prior to a constant-voltage step by approximately 3x. Here, we review several charge-protocol advances, aging factors which are enhanced by XFC and advances which will enable adoption of XFC capable vehicles. These advances include implementing machine learning and other detection algorithms to reduce and classify lithium plating, which is known to significantly degrade cell performance and reduce cell life. The review concludes by discussing full-system fast charge requirements, including electric vehicle service equipment needs for implementing XFC protocols.

25 ENERGY STORAGE↗
DOE OSTI2021

Directional amorphization of covalently-bonded solids: A generalized deformation mechanism in extreme loading

Shock compression subjects materials to a unique regime of high quasi-hydrostatic pressure and coupled shear stresses for durations on the order of 1–10 nanoseconds for laser-driven loading of samples. There is, additionally, an attendant temperature increase due to the shock and the mechanisms of plastic deformation in metals whereby dislocations, twins, and phase transitions nucleate and propagate at velocities near the sound speed. Covalently bonded materials have, by virtue of the directionality of their bonds, great difficulty in responding by conventional plastic deformation to this extreme regime of shock compression. Here, we propose that the shear from shock compression induces amorphization, as observed in Si, Ge, B4C, SiC, and olivine ((Mg, Fe) 2 SO 4 ) and that this is a general deformation mechanism in a broad class of covalently bonded materials. The crystalline structure transforms to amorphous along regions of maximum shear stress, forming nanoscale bands, and thereby relaxing the shear component of the imposed shock stress. This process is usually preceded by the emission and propagation of a critical concentration of dislocations.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Iron acquisition and mineral transformation by cyanobacteria living in extreme environments

Iron is an essential micronutrient for most living organisms, including cyanobacteria. These microorganisms have been found in Earth's driest polar and non-polar deserts, including the Atacama Desert, Chile. Iron-containing minerals were identified in colonized rock substrates from the Atacama Desert, however, the interactions between microorganisms and iron minerals remain unclear. In the current study, we determined that colonized gypsum rocks collected from the Atacama Desert contained both magnetite and hematite phases. A cyanobacteria isolate was cultured on substrates consisting of gypsum with embedded magnetite nanoparticles. Transmission electron microscopy imaging revealed a significant reduction in the size of magnetite nanoparticles due to their dissolution, which occurred around the microbial biofilms. Concurrently, hematite was detected, likely from the oxidation of the magnetite nanoparticles. Higher cell counts and production of siderophores were observed in cultures with magnetite nanoparticles suggesting that cyanobacteria were actively acquiring iron from the magnetite nanoparticles. Magnetite dissolution and iron acquisition by the cyanobacteria was further confirmed using large bulk magnetite crystals, uncovering a survival strategy of cyanobacteria in these extreme environments.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Extreme ultraviolet transient gratings: A tool for nanoscale photoacoustics

Collective lattice dynamics determine essential aspects of condensed matter, such as elastic and thermal properties. These exhibit strong dependence on the length-scale, reflecting the marked wavevector dependence of lattice excitations. The extreme ultraviolet transient grating (EUV TG) approach has demonstrated the potential of accessing a wavevector range corresponding to the 10s of nm length-scale, representing a spatial scale of the highest relevance for fundamental physics and forefront technology, previously inaccessible by optical TG and other inelastic scattering methods. In this manuscript we report on the capabilities of this technique in the context of probing thermoelastic properties of matter, both in the bulk and at the surface, as well as discussing future developments and practical considerations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Recent developments in photoresists for extreme-ultraviolet lithography

Here, this report describes recent developments and current needs in the field of high-resolution photopolymers and photomolecules briefly describing prior generation lithographic patterning materials. It subsequently concentrates on recent advances in both inorganic and polymeric materials for extreme ultraviolet (EUV) lithography. It is also part of a series of papers written in celebration of the centenary of the Polymeric Materials: Science and Engineering (PMSE) division of the American Chemical Society (ACS). PMSE has long been home to polymer chemists who have made important contributions to advances in semiconductor manufacturing as a result of PMSE's focus on polymer coatings research. While EUV lithography has been an area of research for several decades, only within the last 5 years has the combination of new light sources, EUV optics, tool advances and resist discoveries come together to transition this area from the patterning method of the future to a leading-edge manufacturing technology.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Optical, structural and aging properties of Al/Sc-based multilayers for the extreme ultraviolet

This manuscript presents the structural characterization of Al/Sc-based periodic multilayer coatings for the extreme ultraviolet (EUV) spectral range. Based on transmission electron microscopy and electron diffraction as well as grazing-incidence and large-angle x-ray diffraction, a model for the layer structure and the interfacial effects of Al/Sc coatings is built. The onset of crystallization in nanoscale Al and Sc layers as a function of thickness is also revealed in these characterizations. The Al/Sc layer model is validated and further refined by fitting in-band and out-of-band EUV reflectance measurements across 5 orders of magnitude in an extended wavelength range from 17 to 80 nm. Here, the same type of EUV reflectance measurements is used to test the Al/Sc aging properties and to demonstrate the spectral response of optimized two- and tri-material multilayers including Al/Sc, Al/Sc/SiC and Mo/Al/Sc.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Ultrasonic measurement of temperature distributions in extreme environments: Electrical power plants testing in utility-scale steam generators

Thermal heterogeneities within energy conversion and storage, material processing, nuclear processes, aerospace, and military applications are often inaccessible to characterization by insertion sensors. When sensor deployment is possible, conventional pointwise temperature probes quickly degrade when inserted into harsh environments typical of such processes. We developed spatially-resolved ultrasonic thermometry to noninvasively measure the spatial distributions of thermal properties in such applications, even when sizable thermal gradients are present. Our method divides the path of ultrasonic propagation into segments bound by echogenic features, which create echoes in pulse-echo mode, encoding the information about interior temperature distributions. We use the acquired ultrasonic responses to estimate the internal temperature distributions by solving an inverse problem or concatenating segmental estimates. This work describes the implementation and industrial testing of the developed method at a coal-fired electrical power generation plant. We inserted an echogenically segmented Inconel 625 waveguide into the combustion zone of the utility-scale boiler and continuously acquired ultrasonic data while keeping sensitive components away from the damaging combustion environment. The accuracy of the time-dependent temperature distributions reconstructed from the ultrasonic measurements was comparable to that of thermocouples. The resiliency of ultrasonic thermometry to harsh combustion conditions was far superior to conventional insertion sensors. The measurements obtained during plant operation captured daily steam generation cycles in response to changing customer demand and intermittent contributions of renewable power sources to the power grid. These measurements have revealed new insights into the relationship between the dynamic power generation load and the conditions inside the steam generator. As a result, the successful industrial testing of spatially-resolved ultrasonic thermometry in solids indicates that the developed technology has matured to become an attractive alternative to conventional sensing in solving challenging problems of long-term thermal characterizations in extreme environments.

42 ENGINEERING↗
DOE OSTI2024

Enhancing thermal resilience of US residential homes in hot humid climates during extreme temperature events

Increasing occurrences of extreme weather events such as winter storms and heat waves due to climate change pose enormous safety and health-related risks to people, particularly in economically disadvantaged communities. In this study, we investigate some of the most promising retrofittable and weatherization methods to keep the living zone of residential buildings within an acceptable safety level. We use hours of safety as the resilience metric, which is defined as the time taken by the building's indoor environment to reach a safety threshold temperature. We first identify various passive measures, such as adding extra insulation, improving air sealing, and integrating phase-change materials, which can operate without any external power during winter-storm and heat-wave events. We then employ a whole-building simulation tool to examine the impact of various combinations of retrofit measures and conduct a parametric study to determine the optimal solutions.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Exploring Coupled Extreme Environments via In-situ Transmission Electron Microscopy

In-situ transmission electron microscopy (TEM) provides an avenue to explore time-dependent nanoscale material changes induced by a wide range of environmental conditions that govern material performance and degradation. The In-situ Ion Irradiation TEM (I 3 TEM) at Sandia National Laboratories is a JEOL 2100 microscope that has been highly modified with an array of hardware and software that makes it particularly well suited to explore fundamental mechanisms that arise from coupled extreme conditions. Here, examples pertaining to multibeam ion irradiation, rapid thermal cycling, and nanomechanical testing on the I 3 TEM are highlighted, along with prospective advancements in the field of in-situ microscopy.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Measuring Photoexcited Electron and Hole Dynamics in ZnTe and Modeling Excited State Core-Valence Effects in Transient Extreme Ultraviolet Reflection Spectroscopy

Transient extreme ultraviolet (XUV) spectroscopy is becoming a valuable tool for characterizing solar energy materials because it can separate photoexcited electron and hole dynamics with element specificity. We use surface-sensitive femtosecond XUV reflection spectroscopy to separately measure photoexcited electron, hole, and band gap dynamics of ZnTe, a promising photocathode for CO 2 reduction. We develop an ab initio theoretical framework based on density functional theory and the Bethe-Salpeter equation to robustly assign the complex transient XUV spectra to the material's electronic states. Applying this framework, we identify the relaxation pathways and quantify their time scales in photoexcited ZnTe, including subpicosecond hot electron and hole thermalization, surface carrier diffusion, ultrafast band gap renormalization, and evidence of acoustic phonon oscillations.

14 SOLAR ENERGY↗
DOE OSTI2024

Tailoring-Orientated Deposition of Li 2 S for Extreme Fast-Charging Lithium–Sulfur Batteries

Precipitation/dissolution of insulating Li 2 S has long been recognized as the rate-determining step in lithium-sulfur (Li-S) batteries, which dramatically undermines sulfur utilization at elevated charging rates. Herein, we present an orientated Li 2 S deposition strategy to achieve extreme fast charging (XFC, ≤15 min) through synergistic control of porosity, electronic conductivity, and anchoring sites of electrode substrate. Via magnesiothermic reduction of a zeolitic imidazolate framework, a nitrogen-doped and hierarchical porous carbon with highly graphitic phase was developed. This design effectively reduces interfacial resistance and ensures efficient sequestration of polysulfides during deposition, leading to (110)-preferred growth of Li 2 S nanocrystalline between (002)-dominated graphitic layers. Our approach directs an alternative Li 2 S deposition pathway to the commonly reported lateral growth and 3D thickening growth mode, ameliorating the electrode passivation. Therefore, a Li-S cell capable of charging/discharging at 5C (12 min) while maintaining excellent cycling stability (82% capacity retention) for 1000 cycles is demonstrated. In conclusion, even under high S loading (8.3 mg cm -2 ) and low electrolyte/sulfur ratio (3.8 mL mg -1 ), the sulfur cathode still delivers a high areal capacity of >7 mAh cm -2 for 80 cycles.

25 ENERGY STORAGE↗
DOE OSTI2022

New Evidence for the Importance of Non-Stomatal Pathways in Ozone Deposition During Extreme Heat and Dry Anomalies

Dry deposition could partially explain the observed response in ambient ozone to extreme hot and dry episodes. We examine the response of ozone deposition to heat and dry anomalies using three long-term co-located ecosystem-scale carbon dioxide, water vapor and ozone flux measurement records. We find that, as expected, canopy stomatal conductance generally decreases during days with dry air or soil. However, during hot days, concurrent increases in non-stomatal conductance are inferred at all three sites, which may be related to several temperature-sensitive processes not represented in the current generation of big-leaf models. This may offset the reduction in stomatal conductance, leading to smaller net reduction, or even net increase, in total deposition velocity. We find the response of deposition velocity to soil dryness may be related to its impact on photosynthetic activity, though considerable variability exists. Our findings emphasize the need for better understanding and representation of non-stomatal ozone deposition.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Amplified Extreme Floods and Shifting Flood Mechanisms in the Delaware River Basin in Future Climates

Abstract Historical records in the Delaware River Basin reveal complex and spatially diverse flood generating mechanisms influenced by the region's mountains‐to‐plains gradients. This study focuses on predicting future flood hazards and understanding the underlying drivers of changes across the region. Using a process‐based hydrological model, we analyzed the hydrometeorological condition of each historical and future flood event. For each event, at the subbasin scale, we identified the dominant flood generating mechanism, including snowmelt, rain‐on‐snow, short‐duration rain, and long‐duration rain. The rain‐induced floods are further categorized based on the soil's Antecedent Moisture Condition (AMC) before the event, whether dry, normal, or wet. Our historical analysis suggests that rain‐on‐snow is the primary flood mechanism of the Upper Basin. Although most frequent, the magnitude of rain‐on‐snow floods is often less severe than short rain floods. In contrast, historical floods in the Lower Basin are primarily caused by short rain under normal AMC. Given the uncertainties in climate projections, we used an ensemble of future climate scenarios for flood projections. Despite variations in regional climate projections, coherent perspectives emerge: the region will shift toward a warmer, wetter climate, with a projected intensification of extreme floods. The Upper Basin is projected to experience a marked decrease in rain‐on‐snow floods, but a substantial increase in short rain floods with wet AMC. The largest increase in flood magnitude will be driven by short rains with wet AMC in the Upper Basin and by short rains with normal AMC in the Lower Basin.

54 ENVIRONMENTAL SCIENCES↗