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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Packaging Technology for Dielectric-Coating-Less Heavy Ion Radiation Testing of High-Voltage (HV) Electronic Parts

Testing high voltage (HV) electronic parts (greater than 300 V) for sudden event effects (SEE) caused by cosmic rays in the space environment, consisting of energetic heavy-ions, and neutron radiation in the upper atmosphere is a crucial step towards using these parts in spacecraft and aircraft. Due to the nature of cosmic radiation and neutrons, electronic parts are tested for SEE without any packaging and/or shielding over the top of the device. In the case of commercial HV parts, the top of the packaging is etched off and then a thin dielectric coating is placed over the part in order to avoid electrical arcing between the device surface and wire bonds and other components. Even though the effects of the thin dielectric layer on SEE testing can be accounted for, the dielectric layer significantly hinders post testing failure analysis. Replicating the test capability of state-of-the-art packaging while eliminating the need for post radiation test processing of the die surface (that obscures failure analysis) is the goal. To that end, a new packaging concept for HV parts has been developed that requires no dielectric coating over the part. Testing of prototype packages used with Schottky diodes (rated at 1200V) has shown no electrical arcing during testing and leakage currents during reverse bias testing are within the manufactures specifications.

High Voltage↗
NASA NTRS2024

GVIPS Prediction of Cyclic Ratchetting Behavior and Cycles With Interrupted Relaxation Periods of TIMETAL 21S at 650 oC

The predictive performance of a multimechanism GVIPS model with saturating hardening function is assessed against a set of high temperature cyclic experiments under both strain-control and stress-control at varying rates of loading as well as several complex interrupted cyclic responses. The material specimens were composed of the titanium alloy, TIMETAL 21S, and tested at 650oC, see Lissenden et al., 2007. The model did a very good job of predicting the variety of tests, particularly given the fact that only monotonic loading tests (tensile, creep, relaxation) and a single fully reversed cycle was used for characterization. It was particularly interesting that the model was capable of reasonably capturing the rate of accumulated strain during ratchetting under tensile mean stress. Given complex interrupted cyclic response, the model was able to both qualitatively and even quantitatively predict reasonably well both the cyclic and associated relaxation periods (in all quadrants of the stress-strain space) thus confirming the validity of the chosen functional forms for both hardening and thermal recovery. The quantitative inaccuracy is associated with the fact that the material specimens tested by Lissenden et al., 2007 was significantly “softer” than those tested by Castelli in Saleeb et al., 1994 which were used for characterization of the GVIPS model parameters.

Viscoplaticity↗
DOE OSTI2020

Reducing nitrous oxide emissions and optimizing nitrogen-use efficiency in dryland crop rotations with different nitrogen rates

Recent interests in improving agricultural production while minimizing environmental footprints emphasized the need for research on management strategies that reduce nitrous oxide (N 2 O) emissions and increase nitrogen-use efficiency (NUE) of cropping systems. This study aimed to evaluate N 2 O emissions, annualized crop grain yield, emission factor, and yield-scaled- and NUE-scaled N 2 O emissions under continuous spring wheat (Triticum aestivum L.) (CW) and spring wheat-pea (Pisum sativum L.) (WP) rotations with four N fertilization rates (0, 50, 100, and 150 kg N ha(-1)). The N 2 O fluxes peaked immediately after N fertilization, intense precipitation, and snowmelt, which accounted for 75-85% of the total annual flux. Cumulative N 2 O flux usually increased with increased N fertilization rate in all crop rotations and years. Annualized crop yield and NUE were greater in WP than CW for 0 kg N ha(-1) in all years, but the trend reversed with 100 kg N ha(-1) in 2013 and 2015. Crop yield maximized at 100 kg N ha(-1), but NUE declined linearly with increased N fertilization rate in all crop rotations and years. As N fertilization rate increased, N fertilizer-scaled N2O flux decreased, but NUE-scaled N 2 O flux increased non-linearly in all years, regardless of crop rotations. The yield-scaled N 2 O flux decreased from 0 to 50 kg N ha -1 and then increased with increased N fertilization rate. Because of non-significant difference of N 2 O fluxes between 50 and 100 kg N ha(-1), but increased crop yield, N 2 O emissions can be minimized while dryland crop yields and NUE can be optimized with 100 kg N ha -1 , regardless of crop rotations.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2026

GVIPS Prediction of Cyclic Ratchetting Behavior and Cycles with Interrupted Relaxation Periods of TIMETAL 21S at 650 °C

The predictive performance of a multimechanism GVIPS model with saturating hardening function is assessed against a set of high temperature cyclic experiments under both strain-control and stress-control at varying rates of loading as well as several complex interrupted cyclic responses. The material specimens were composed of the titanium alloy, TIMETAL 21S, and tested at 650 °C, see Lissenden et al., 2007. The model did a very good job of predicting the variety of tests, particularly given the fact that only monotonic loading tests (tensile, creep, relaxation) and a single fully reversed cycle was used for characterization. It was particularly interesting that the model was capable of reasonably capturing the rate of accumulated strain during ratchetting under tensile mean stress. Given complex interrupted cyclic response, the model was able to both qualitatively and even quantitatively predict reasonably well both the cyclic and associated relaxation periods (in all quadrants of the stress-strain space) thus confirming the validity of the chosen functional forms for both hardening and thermal recovery. The quantitative inaccuracy is associated with the fact that the material specimens tested by Lissenden et al., 2007 was significantly “softer” than those tested by Castelli in Saleeb et al., 1994 which were used for characterization of the GVIPS model parameters.

Viscoplaticity↗
DOE OSTI2014

Time of Flight Electrochemistry: Diffusion Coefficient Measurements Using Interdigitated Array (IDA) Electrodes

A simple and straightforward method for measuring diffusion coefficients using interdigitated array (IDA) electrodes is reported. The method does not require that the exact electrode area be known but depends only the size of the gap between the IDA electrode pairs. Electroactive molecules produced at the generator electrode of the IDA by a voltage step or scan can diffuse to the collector electrode and the time delay before the current for the reverse electrochemical reaction is detected at the collector is used to calculate the diffusion coefficient. The measurement of the diffusion rate of Ru(NH3)6+2 in aqueous solution has been used as an example measuring diffusion coefficients using this method. Additionally, a digital simulation of the electrochemical response of the IDA electrodes was used to simulate the entire current/voltage/time behavior of the system and verify the experimentally measured diffusion coefficients. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences.

Liu, Fei↗
DOE OSTI2013

Solid electrolyte coated high voltage layered–layered lithium-rich composite cathode: Li 1.2 Mn 0.525 Ni 0.175 Co 0.1 O 2

We find that the electrochemical rate performance and capacity retention of the “layered–layered” lithium rich Li 1.2 Mn 0.525 Ni 0.175 Co 0.1 O 2 (Li-rich NMC) material are significantly improved by a nanometer layer coating of a lithium conducting solid electrolyte, lithium phosphorus oxynitride (LiPON). The LiPON layer is deposited on the Li-rich NMC particles by the RF-magnetron sputtering method. The presence of the LiPON layer provides interfacial stability under high current (rate) and voltage cycling conditions and thereby improves the capacity retention over cycle life compared to pristine or uncoated Li-rich NMC. Specifically, the LiPON coated Li-rich NMC composite electrode showed stable reversible capacities of >275 mAh g -1 when cycled to 4.9 V for more than 300 cycles, and showed at least threefold improvements in the rate performance compared to the uncoated electrode compositions. Increasing the LiPON layer thickness beyond a few nanometers leads to capacity fade due to increasing electronic resistance. Lastly, detailed microstructural and electrochemical impedance spectroscopy studies are undertaken to characterize and understand the role of LiPON in improving the interfacial stability and electrochemical activity at the interface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1976

Mars - Chemical weathering as a massive volatile sink

The amounts of volatiles incorporated in the Martian regolith by photostimulated oxidation weathering of Fe(2+)-bearing minerals are estimated. The process of photostimulated oxidation weathering is described, and it is noted that all the necessary constituents for this process are present on Mars. The rates at which oxygen and hydrogen are irreversibly removed from the Martian atmosphere by the present process are determined, irreversible and reversible water losses are considered, and the loss of CO2 by carbonate formation is shown to be irreversible. The results suggest that photostimulated oxidation weathering has irreversibly consumed 100 to 100,000 g/sq cm of H2O and 10 to 10,000 g/sq cm of CO2, assuming a uniform rate over geologic time. It is concluded that if the amounts of H2O and CO2 actually removed by photostimulated oxidation are close to the upper limits of the present estimates, then that process may have had a major effect in limiting the amount of H2O and CO2 trapped in the regolith and polar caps.

Huguenin, R. L.↗
DOE OSTI2017

Dynamic Uniaxial Compression of HSLA-65 Steel at Elevated Temperatures

Here, the dynamic response of a high-strength, low alloy Grade 65 (HSLA-65) steel, used by the United States Navy for ship hull construction, is investigated under dynamic uniaxial compression at temperatures ranging from room temperature to 1000 °C using a novel elevated temperature split-Hopkinson pressure bar. These experiments are designed to probe the dynamic response of HSLA-65 steel in its single α-ferrite phase, mixed α + γ-austenite phase, and the single γ-austenite phase, as a function of temperature. The investigation is conducted at two different average strain rates—1450 and 2100/s. The experimental results indicate that at test temperatures in the range from room temperature to lower than 600 °C, i.e. prior to the development of the mixed α + γ phase, a net softening in flow strength is observed at all levels of plastic strain with increase in test temperatures. As the test temperatures are increased, the rate of this strain softening with temperature is observed to decrease, and at 600 °C the trend reverses itself resulting in an increase in flow stress at all strains tested. This increase in flow stress is understood be due to dynamic strain aging, where solute atoms play a distinctive role in hindering dislocation motion. At 800 °C, a (sharp) drop in the flow stress, equivalent to one-half of its value at room temperature, is observed. As the test temperature are increased to 900 and 1000 °C, further drop in flow stress are observed at all plastic strain levels. In addition, strain hardening in flow stress is observed at all test temperatures up to 600 °C; beyond 800 °C the rate of strain hardening isobserved to decrease, with strain softening becoming dominant at temperatures of 900 °C and higher. Moreover, comparing the high strain rate stress versus strain data gathered on HSLA 65 in the current investigation with those available in the literature at quasi-static strain rates, strain-rate hardening can be inferred. The flow stress increases from 700 MPa at 8 × 10 -4 /s to 950 MPa at 1450/s and then to 1000 MPa at 2100/s at a strain of 0.1. Finally, optical microscopy is used to understand evolution of microstructure in the posttest samples at the various test temperatures employed in the present study.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Machine learning modeling and model predictive control of a closed-circuit reverse osmosis system

Closed-circuit reverse osmosis (CCRO) offers a flexible and energy-efficient alternative to conventional reverse osmosis by operating in a semi-batch mode that recycles brine, enabling higher recovery rates and reduced specific energy consumption (SEC). However, developing accurate, system-level dynamic models for CCRO remains challenging due to its nonlinear, multi-phase operation and sensitivity to variable feed water conditions. Traditional modeling approaches, such as NARMAX (nonlinear autoregressive moving average with exogenous inputs), often struggle to generalize across varying inlet feed concentrations, necessitating frequent parameter re-estimation and limiting their utility for real-time control applications. To address these limitations, we developed a long short-term memory (LSTM) neural network model trained on an extensive experimental data set from a CCRO pilot plant. The model accepts three inputs, feed flow rate, recirculation flow rate, and initial feed conductivity, and predicts three key outputs: reject conductivity, feed pump power draw, and recirculation pump power draw. We validated the LSTM model against experimental data, demonstrating its ability to distinguish between different feed conductivities and adapt to variable flow rates. Subsequently, we incorporated the LSTM model within a nonlinear model predictive control (MPC) scheme and conducted closed-loop simulations to optimize the integrated SEC (iSEC). In conclusion, the results project up to a 6% reduction in iSEC by using MPC to optimize performance over the entire experiment duration, without requiring any random excitation for data collection or parameter re-estimation.

Desalination↗
DOE OSTI2020

A High-Performance Na-Al Battery Based on Reversible NaAlCl4 Catholyte

This work demonstrates a high-capacity and safe Na-Al battery pairing sodium metal anode and reversible NaAlCl4 catholyte for grid scale energy storage applications. The energy-rich sodium anode allows the full play of the aluminum cathode, resulting in a full-cell capacity of 308 mAh/g at a discharge voltage of 1.6 V. Benefiting from the use of ??-alumina solid electrolyte (BASE), molten sodium anode and reversible Al deposition/stripping from NaAlCl4 catholyte, the battery presents a stable Coulombic efficiency of 100% and energy efficiency of ~95%. At a rate of C/3 (6.77 mA/cm2), the cell maintains 282 mAh/g (447 Wh/kg) after 200 cycles with an excellent capacity retention of 97.6%. Moreover, we elucidate pathways to build sodium-anode-free cells from the discharged state under dry air, which further extends the feasibility of this battery for stationary storage applications. These findings are expected to provide a new platform for the development of practical Al batteries.

Zhan, Xiaowen↗
NASA NTRS1982

The mechanical design of a vapor compressor for a heat pump to be used in space

A heat pump developed for use in Spacelab as a stand-alone refrigeration unit as well as within a fluid loop system is discussed. It will provide an active thermal control for payloads. Specifications for the heat pump were established: (1) heat removal rates at the source; (2) heat source temperatures from room temperature; (3) heat-sink fluid temperatures at condenser inlet; and (4) minimum power consumption. A reversed Carnot cycle heat pump using Freon 12 as working fluid incorporating a one-cylinder reciprocating compressor was selected. The maximum crankshaft speed was fixed relatively high at 100 rpm. The specified cooling rates then made it necessary to select a cylinder volume of 10 cu cm, which was obtained with a bore of 40 mm and a stroke of 8 mm.

Berner, F.↗
DOE OSTI2017

Revealing mechanism responsible for structural reversibility of single-crystal VO 2 nanorods upon lithiation/delithiation

A pure phase of VO 2 (B) nanorods have been synthesized through an energy-efficient microwave hydrothermal reaction and used as cathode materials of lithium ion batteries, which exhibit promising specific capacity (e.g., 130 mA h g -1 even after 100 charge/discharge cycles) and rate capacity (e.g., ~130 mA h g -1 at a high current of 400 mA g -1 ). The excellent cyclability originates from the structural reversibility of VO 2 (B) upon lithiation/delithiation that is confirmed by the in situ high-energy synchrotron X-ray diffraction (HEXRD) and in situ x-ray adsorption near-edge spectroscopy (XANES) of the VO 2 nanorods in operating battery cells. As a result, the real-time results reveal that discharge forces lithium ions to insert firstly into the tunnels with the largest size along b direction followed by the second largest tunnels along c direction, which is completely reversible in the charge process.

36 MATERIALS SCIENCE↗
NASA NTRS2017

Reversible and Irreversible Time-Dependent Behavior of GRCop-84

A series of mechanical tests were conducted on a high-conductivity copper alloy, GRCop-84, in order to understand the time dependent response of this material. Tensile, creep, and stress relaxation tests were performed over a wide range of temperatures, strain rates, and stress levels to excite various amounts of time-dependent behavior. At low applied stresses the deformation behavior was found to be fully reversible. Above a certain stress, termed the viscoelastic threshold, irreversible deformation was observed. At these higher stresses the deformation was observed to be viscoplastic. Both reversible and irreversible regions contained time dependent deformation. These experimental data are documented to enable characterization of constitutive models to aid in design of high temperature components.

viscoelasticity↗
DOE OSTI2018

Facile electrostatic self-assembly of silicon/reduced graphene oxide porous composite by silica assist as high performance anode for Li-ion battery

Silicon(Si)/graphene composite has been regarded as one of the most promising candidates for next generation anode materials with high power and energy density in lithium ion batteries. Introduction of graphene in Si anodes could improve the electronic conductivity, suppress the severe volume expansion of Si, and facilitate the formation of stable solid electrolyte interphase, etc. However, traditionally mechanical mixing of Si and graphene cannot realize uniform distribution of Si particles on the graphene sheets, which would largely weaken the effectiveness of the graphene in the composite. In this work, nano-Si/reduced graphene oxide porous composite (p Si/rGO) has been fabricated by a facile electrostatic self-assembly approach via using SiO2 as the sacrificial template. Compared with the simply mechanically mixed nano-Si and rGO (Si/rGO), the nano-Si particles could be more uniformly dispersed among the rGO sheets in the p Si/rGO, which significantly increases its electronic conductivity. Moreover, the drastic volume expansion of nano-Si during repeated lithiation/delithiation cycles also has been effectively accommodated by the large number of pores left after removing the SiO2 template in the composite. Thus, the p Si/rGO presented largely enhanced electrochemical performances, showing a high reversible capacity up to 1849?mA?h?g-1 at 0.2?A?g-1 with good capacity retention, and high rate capability (535?mA?h?g-1 at 2?A?g-1).

Silicon, Reduced graphene oxide, Electrostatic sel↗
DOE OSTI2018

Self-Templated Formation of P2-type K 0.6 CoO 2 Microspheres for High Reversible Potassium-Ion Batteries

We report that layered metal oxides have been widely used as the best cathode materials for commercial lithium-ion batteries and are being intensively explored for sodium-ion batteries. However, their application to potassium-ion batteries (PIBs) is hampered because of the poor cycling stability and low rate capability due to the larger ionic size of K + than of Li + or Na + . Herein, a facile self-templated strategy was used to synthesize unique P2-type K 0.6 CoO 2 microspheres that consist of aggregated primary nanoplates as PIB cathodes. The unique K 0.6 CoO 2 microspheres with aggregated structure significantly enhanced the kinetics of the K + intercalation/deintercation and also minimized the parasitic reactions between the electrolyte and K 0.6 CoO 2 . The P2-K 0.6 CoO 2 microspheres demonstrated a high reversible capacity of 82 mAh g –1 at 10 mA g –1 , high rate capability of 65 mAh g –1 at 100 mA g –1 , and long cycle life (87% capacity retention over 300 cycles). The high reversibility of the P2-K 0.6 CoO 2 full cell paired with a hard carbon anode further demonstrated the feasibility of PIBs. Lastly, this work not only successfully demonstrates exceptional performance of P2-type K 0.6 CoO 2 cathodes and microspheres K 0.6 CoO 2 ∥hard carbon full cells, but also provides new insights into the exploration of other layered metal oxides for PIBs.

25 ENERGY STORAGE↗
DOE OSTI2022

An Ultrafast, Durable, and High-Loading Polymer Anode for Aqueous Zinc-Ion Batteries and Supercapacitors

Zn metal has shown promise as an anode material for grid-level energy storage, yet is challenged by dendritic growth and low Coulombic efficiency. Herein, an ultrafast, stable, and high-loading polymer anode for aqueous Zn-ion batteries and capacitors (ZIBs and ZICs) is developed by engineering both the electrode and electrolyte. The anode polymer is rationally prepared to have a suitable electronic structure and a large pi-conjugated structure, whereas the electrolyte is manufactured based on the superiority of triflate anions over sulfate anions, as analyzed and confirmed via experiments and simulations. This dual engineering results in an optimal polymer anode with a low discharge potential, near-theoretical capacity, ultrahigh-loading capability (approximate to 50 mg cm -2 ), ultrafast rate (100 A g -1 ), and ultralong lifespan (one million cycles). Further, its mechanism involves reversible Zn 2+ /proton co-storage at the carbonyl site. When the polymer anode is coupled with cathodes for both ZIB and ZIC applications, the devices demonstrate ultrahigh power densities and ultralong lifespans, far surpassing those of corresponding Zn-metal-based devices.

25 ENERGY STORAGE↗
DOE OSTI2015

Type I clathrates as novel silicon anodes: An electrochemical and structural investigation

In this study, silicon clathrates contain cage-like structures that can encapsulate various guest atoms or molecules. Here we present an electrochemical evaluation of type I silicon clathrates based on Ba 8 Al y Si 46-y for the anode material in lithium-ion batteries. Post-cycling characterization with NMR and XRD show no discernible structural or volume changes even after electrochemical insertion of 44 Li into the clathrate structure. The observed properties are in stark contrast with lithiation of other silicon anodes, which become amorphous and suffer from larger volume changes. The lithiation/delithiation processes are proposed to occur in single phase reactions at approximately 0.2 and 0.4 V vs. Li/Li + , respectively, distinct from other diamond cubic or amorphous silicon anodes. Reversible capacities as high as 499 mAh g -1 at a 5 mA g -1 rate were observed for silicon clathrate with composition Ba 8 Al 8.54 S i37.46 , corresponding to Li:Si of 1.18:1. The results show that silicon clathrates could be promising durable anodes for lithium-ion batteries.

36 MATERIALS SCIENCE↗