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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 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Challenges in computationally designing high temperature Fe-based austenitic alloys: Addressing the role of Ni additions

Alumina-forming austenitic (AFA) alloys are relatively inexpensive high performance materials which combine the creep resistance of low-cost austenitic alloys and the oxidation resistance of expensive alumina forming alloys. However, a fundamental understanding of the role of key alloying elements such as Ni, Cr, Al, Nb, Ti, V, B and C in the experimentally observed oxidation behavior of these alloys is still lacking. The present work is a first in a series of studies aiming to quantitatively describe the role of Ni in promoting or disrupting protective Al 2 O 3 scale formation on AFA alloys. Here, ternary Fe-Al-xNi model alloys with three different Ni contents were isothermally exposed in an atmosphere with a low partial pressure of oxygen between 800–1000 °C for 24 h to evaluate the role of Ni in the observed internal oxidation behavior. Increasing Ni contents had no impact on the internal oxidation behavior of the alloys. The experimental and theoretical analyses in the present work suggested a negligible effect of the internal oxide precipitates on the inward diffusion of oxygen, typically expected in these systems, while simultaneously highlighting the barriers in the development of reliable models for computation-assisted design of these alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Anomalous fast atomic dynamics in bulk metallic glasses

It is believed that the strong glass formers tend to be dense packing and have rather slow atomic dynamics. Here, we report that the anomalous fast atomic dynamics exist in an Au 55 Cu 20 Ag 5 Si 20 metallic glass (MG) with good glass forming ability (GFA) by combining X-ray photon correlation spectroscopy measurements with ab initio molecular dynamics simulations. The fast dynamics are mainly originated from the increased mobility of Cu atoms by Ag addition. Ag atoms are inclined to locate at Cu-centered <0, 2, 8, 1> motifs, which slow or accelerate the dynamics of shell Cu atoms, depending on whether Ag atoms appear at the first shells or not, leading to the formation of structural heterogeneity at the atomic level. The results enrich the understanding of atomic dynamics in Cue-Ag-containing MGs and will trigger more studies on the dynamics-GFA relationship in MGs.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2023

Dense Ru single-atoms integrated with sulfoacids for cellulose valorization to isosorbide

Metal-acid bifunctional catalysts are the unity of two opposites (metal-acid repelling) for cellulosic biomass valorization to isosorbide. It is challenging to improve the selectivity of metal hydrogenation catalysts and their synergism with acids for catalytic hydrolysis and dehydration to achieve substantial isosorbide. Herein, dense Ru single-atoms (10.1 wt% of Ru SAs) are anchored on sulfoacid-functionalized hollow mesoporous carbon shells, designed by assembling silica and 8-hydroxyquinoline-modified chitosan (HQ-CTS) through in situ Stöber templating strategy before pyrolysis and acid treatment. Based on X-ray absorption fine structure and computational modeling results, the structure of Ru SAs is determined as RuN 4 , which is more selective for a transitional glucose hydrogenation to sorbitol than Ru001 of Ru clusters. A lower-energy barrier of 1.21 (0.72) eV is delivered over RuN 4 (Ru001) for glucose hydrogenation (isomerization). These Ru SAs are integrated with sulfoacids (SO 3 H) but resistent against acids, rendering enhanced isosorbide yield in water as compared to Ru clusters, via a one-pot cascade reaction under harsh conditions (220 °C, 6 MPa H 2 ). The elaborately fabricated dense Ru SAs and sulfoacids, achieved by varying the addition time of HQ-CTS during the in situ Stöber templating process, improve the synergism of glucose hydrogenation with cellulose hydrolysis and sorbitol dehydration. In conclusion, this study provides a new idea for rational design of high-performance metal-acid bifunctional catalysts toward one-pot conversion of cellulose to isosorbide.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Support size regulated ruthenium-sulfoacid-nitrogen sites intensify cellulose hydrogenolysis to 1,2-propylene glycol

Rational design of metal-acid-base multifunctional catalysts for upgrading cellulose to 1,2-propylene glycol (1,2-PG) is of great significance for building a sustainable world. However, it is time-consuming and tedious to regulate metal-acid-base sites to balance major reactions to render a high 1,2-PG yield. We herein report support size simultaneously regulated ruthenium-sulfoacid-nitrogen (Ru–SO 3 H–N) sites for cellulose hydrogenolysis to high yield 1,2-PG. Originated from the depolymerization and reassembly of zinc-1,3,5-benzenetricarboxylic acid (ZnBTC) fiber with zeolitic imidazolate framework (ZIF-8) in water, 2-methylimidazole infiltrated nanorod (ZnBTC(mIM)) with a varied aspect ratio was fabricated by varying the feed ratio of ZIF-8/ZnBTC. Upon being pyrolyzed, sulfonated and impregnated with Ru ions, the supported sites were tailored in terms of Ru single-atom/nanocluster ratio, SO 3 H acidity and N basicity. Further, the elaborately fabricated catalyst delivers 32.3% yield of 1,2-PG, corresponding to a high productivity of 67.71 mol h -1 g Ru -1 and a large turnover number of 34193, two and three orders of magnitude higher than those by using other Ru-containing catalytic systems for cellulose hydrogenolysis. The excellent performance can be attributed to optimized electronic and molecular structure of Ru–SO 3 H–N sites that can improve rate-determining cellulose hydrolysis/fructose hydrogenolysis, pivotal glucose isomerization with others to proceed at a matched rate. This study opens a new avenue to facilely tailor the metal-acid-base sites by rational design of size controlled supporting matrix.

1,2-Propylene glycol↗
DOE OSTI2020

A practical phosphorus-based anode material for high-energy lithium-ion batteries

State-of-the-art lithium-ion batteries cannot satisfy the increasing energy demand worldwide because of the low specific capacity of the graphite anode. Silicon and phosphorus both show much higher specific capacity; however, their practical use is significantly hindered by their large volume changes during charge/discharge. Although significant efforts have been made to improve their cycle life, the initial coulombic efficiencies of the reported Si-based and P-based anodes are still unsatisfactory (<90%). In this study, by using a scalable high-energy ball milling approach, we report a practical hierarchical micro/nanostructured P-based anode material for high-energy lithium-ion batteries, which possesses a high initial coulombic efficiency of 91% and high specific capacity of ~2500 mAh g –1 together with long cycle life and fast charging capability. In situ high-energy X-ray diffraction and in situ single-particle charging/discharging were used to understand its superior lithium storage performance. Moreover, proof-of-concept full-cell lithium-ion batteries using such an anode and a LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode were assembled to show their practical use. The findings presented here can serve as a good guideline for the future design of high-performance anode materials for lithium-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2020

Size effect on the growth and pulverization behavior of Si nanodomains in SiO anode

Silicon monoxide (SiO) as a promising silicon-based anode electrode of lithium-ion batteries (LIBs) has been the subject of many recent investigations. However, the complex microstructural features of SiO hinder attempts to link the microstructure changes in SiO with its electrochemical performances upon electrochemical cycling. This study employs X-ray pair distribution function (PDF), with a high-resolution transmission electron microscope (HRTEM), to investigate the microstructure of Si nanodomains in SiO and its structural evolution over the electrochemical cycling process. The experiment results reveal the size evolution of Si nanodomains in SiO during the electrochemical cycling and find it highly dependent on the initial Si domain size in SiO. If the initial Si domain size is too large, the average size of Si nanodomains would increase at first and then decrease after a certain number of cycles, which indicates the pulverization of Si domains after the electrochemical-driven growth of Si nanodomains reaches a critical point. Furthermore, these results suggest that an optimal initial Si nanodomain size of 4-6 nm for SiO anode materials is essential to retard the growth and subsequent pulverization process of Si nanodomains and thus to improve the cyclability of SiO during long-term cycling.

25 ENERGY STORAGE↗
DOE OSTI2021

A highly-stable layered Fe/Mn-based cathode with ultralow strain for advanced sodium-ion batteries

Sodium-ion batteries (SIBs) with iron- and manganese-based cathode electrodes have exhibited great promise in the grid-scale energy storage systems, on the basis of the satisfactory theoretical capacity, as well as huge abundance, low price and non-toxicity of raw materials. However, the inferior cycle life of cathode materials originating from their poor structural stability remains a formidable challenge towards practical applications. In this study, an efficient strategy of improving the structure durability is demonstrated in iron- and manganese-based cathodes by dual heteroatom doping. The as-obtained P2-type Na 0.65 Li 0.08 Cu 0.08 Fe 0.24 Mn 0.6 O 2 cathode delivers superior cyclability (88.2% capacity retention for 500 cycles at 2C), fabulous rate capability (76% capacity retention at 5C compared to 0.1C), and a useable reversible capacity of around 85 mAh g -1 at 0.1C. Through in-depth characterizations, the underlying structure-property relationship is established, revealing that the complete solid-solution reaction during cycling ensures the ultralow volume variation (as small as 0.7%) and excellent electrochemical performance. These results highlight the significance of fabricating a stable host for the design and development of advanced SIBs with long life.

25 ENERGY STORAGE↗
DOE OSTI2021

Electronic properties of Ir 3 Li and ultra-nanocrystalline lithium superoxide formation

Current lithium-oxygen (Li-O 2 ) batteries suffer from large charge overpotentials related to electronic resistivity of the insulating lithium peroxide (Li 2 O 2 ) discharge product. One potential solution to this challenge is the stabilization of the lithium superoxide (LiO 2 ) discharge intermediate, which has much higher electronic conductivity compared to Li 2 O 2 . Cathodes based on small iridium (Ir) nanoparticles have been recently used in a LiO 2 battery to successfully stabilize the LiO 2 product, however, the LiO 2 had a short lifetime. In the previous study, researchers found that the LiO 2 was stabilized on Ir 3 Li surfaces which were formed from Ir nanoparticles during battery operation. Little is known about the electronic properties of Ir 3 Li and its role in stabilizing LiO 2 product formation. This work provides the first study of the electronic properties of Ir 3 Li, which was thermally synthesized in bulk prior to implementation on the reduced graphene oxide (rGO) cathode of a Li-O 2 cell. Here, the bulk Ir 3 Li was found to have comparable electrical conductivity to Ir metal, possess metal-like magnetic properties, and has an affinity towards O 2 adsorption. The LiO 2 discharge product formed from the Li-O 2 battery discharge was characterized using Raman spectroscopy, titration, along with a comprehensive transmission electron microscopy (TEM) study. This analysis revealed the formation of ultra-nanocrystalline LiO 2 particles greater than 200 nm. This result was attributed to the use of large micron sized Ir 3 Li particles, which could stabilize larger LiO 2 particles compared to previous cathodes that utilized Ir nanoparticles that partially converted to Ir 3 Li during cycling. These results demonstrate that cathode properties can be modified to stabilize the bulk LiO 2 discharge product, which can be useful for the further development of LiO 2 -based Li-O 2 batteries.

25 ENERGY STORAGE↗
DOE OSTI2022

Targeted masking enables stable cycling of LiNi 0.6 Co 0.2 Mn 0.2 O 2 at 4.6V

Layered LiNi x Co y Mn 1–x-y O 2 (NCM, or NCMxy(1-x-y)) is a dominant family of cathode materials for lithium-ion batteries (LIBs) due to its high energy density. Among all NCM cathode materials, NCM622 possess the optimal energy density at high potential (≥ 4.6 V vs. Li/Li + ). However, the practical application of NCM622 at high voltage (≥ 4.6 V) is limited by its parasitic reactions and associated safety concerns. Completely physical isolation has been considered as the main approach to mitigate the parasitic reaction. It has also been previously demonstrated that the interface reaction has active site selectivity, and that the reactivity of the active sites can effectively suppressed by blocking the chemically active sites. Herein, a targeted masking by LiFePO 4 @C nanoplates is reported to unlock the stable performance of NCM622 up to 4.6 V vs. Li/Li + . The (targeted masked-NCM622)|graphite pouch cell shows 86.5% capacity retention after 1000 cycles and its maximum temperature during thermal runaway is dramatically reduced from 570 °C to 415 °C. Systematic in/ex situ characterizations, first-principles calculations and half/pouch targeted LiFePO 4 @C covers the surface of NCM partcell evaluation prove that PO 4 3- is preferentially adsorbed on transition metal sites, stabilizing both the transition metal ions and oxygen ions on the surface against the ethylene carbonate-containing traditional electrolyte even under high voltage (≥ 4.6 V vs. Li/Li + ). Furthermore, this work opens up new venue for rational design of high-performance cathode materials through a low-cost and scalable decoration process, and reveal a new understanding of interfacial activity of materials.

25 ENERGY STORAGE↗
DOE OSTI2022

Ultrahigh rate capability of manganese based olivine cathodes enabled by interfacial electron transport enhancement

In this study, manganese-based Olivine is a promising cathode candidate with high energy and low cost for Li-ion batteries (LIBs). Its rate capability and cyclability challenges still remain even with nano-size and carbon coating. Herein, an ultrahigh rate performance is achieved by introducing an affinitive conductor to enhance the interfacial electron transport of LiMn 0.7 Fe 0.3 PO 4 via Li 3 V 2 (PO 4 ) 3 . It is found that the Li 3 V 2 (PO 4 ) 3 facilitates sp 2 hybridization to form a highly conductive carbon coating during the carbonized process. The composite 0.9LiMn 0.7 -Fe 0.3 PO 4 .0.1Li 3 V 2 (PO 4 ) 3 can deliver a capacity of 90.9 mAh g -1 and power density of 11444 W kg -1 at 50 C-rate. Both in situ X-ray diffraction and conductive-atomic force microscopy are conducted to understand the synergetic effect between LiMn 0.7 Fe 0.3 PO 4 and Li 3 V 2 (PO 4 ) 3 . The results suggest that the interfacial electron transfer between LiMn 0.2 Fe 0.3 PO 4 particles and the electron conducting medium, such as binder/carbon black composite, is greatly improved so that the highly Li + conductive nature of olivine materials can be fully unleashed. This work demonstrates the importance of efficient interfacial electron transfer to the active cathode particles, and opens up a new venue for the rational design of high-energy and high-power batteries.

25 ENERGY STORAGE↗
DOE OSTI2023

Inhibit the strain accumulation for 5V spinel cathode by mitigating the phase separation during high voltage stage

LiNi 0.5 Mn 1.5 O 4 (LNMO) spinel cathode is a potential cathode material for high-power, low-cost lithium-ion batteries (LIBs) due to its low raw material cost, high operating voltage and efficient lithium-ion transport channel. However, LNMO suffers from structural stability due to the two-phase-transformation during charge/discharge process, leading to poor cycling performance. Here, to address the issues, we have constructed a homogeneous aggregated LNMO cathode with a multifaceted primary particle, namely the LNMO with single-crystal secondary particles (SSP LNMO). Ex situ and in situ characterizations including the synchrotron X-ray diffraction, the neutron diffraction and full pouch cell validated that the SSP LNMO exhibit a single solid-solution reactions with a restrained lattice evolution during the delithiation/lithiation process. This is in contrast to the normal LNMO cathode, which demonstrates a significant two-phase transition from spinel Li 1-x Ni 0.5 Mn 1.5 O 4 to rock-salt MnO 2 at high voltage. Therefore, the SSP LNMO has greatly improved cycle life compared to the normal LNMO cathode. Overall, this study demonstrates the possibility of constructing LNMO based on primary-grain morphology modulation to improve the intrinsic stability of LIBs.

25 ENERGY STORAGE↗
DOE OSTI2024

The role of Li doping in layered/layered Na x Li y Ni 0.4 Fe 0.2 Mn 0.4 O 2 intergrowth electrodes for sodium ion batteries

Here, the layered NaTMO 2 (TM = Ni, Fe, Mn) materials with the O3-type structure are attractive as positive electrodes for sodium ion batteries because of their high theoretical capacity. Additionally, Li doping in these materials has been shown to offer substantial enhancements to their electrochemical properties by promoting the formation of intergrowth structures, which are combinations of specific phases. However, the mechanism by which the intergrowth modifies the electrochemical properties is often unclear. Systematic variation of Li content in Na x Li y Ni 0.4 Fe 0.2 Mn 0.4 O 2 (NFM-Li y ) was conducted to identify its role in structural modification and electrochemical performance. Li contents of 0.15 and greater generate a layered/layered Na-O3/Li-O’3 intergrowth structure. 7 Li and 23 Na nuclear magnetic resonance and x-ray absorption spectroscopy identify that when the total solubility for alkali ions in the layered structure is exceeded, Li continues to form the Li-O’3 phase while the excess Na forms residual sodium compounds such as Na 2 O. Higher Li content is associated with improved capacity retention in the initial cycles from the superior stability of the mechanically linked NaO3/Li-O’3 structure that suppresses the P3 to OP2 phase transition during charge. However, high Li contents are associated with increased rates of parasitic side reactions that reduce long-term cycling stability. These side reactions are associated with the instability of the cathode-electrolyte interphase, which can be partially mitigated by atomic layer deposition (ALD) coating with alumina, which significantly enhances the capacity retention and Coulombic efficiency over many cycles. Overall, we find that the layered/layered Na-O3/Li-O’3 intergrowth structure is able to provide structural stability and suppress undesired phase transformations but is overwhelmed by the increased reactivity of the surface if not protected by surface coating.

25 ENERGY STORAGE↗
DOE OSTI2020

Single electron–hole pair sensitive silicon detector with surface event discrimination

Here, we demonstrate single electron-hole pair resolution in a single-sided, contact-free 1 cm$^2$ by 1 mm thick Si crystal operated at 48 mK, with a baseline energy resolution of 3 eV. This crystal can be operated at voltages in excess of $\pm50$ V, resulting in a measured charge resolution of 0.06 electron-hole pairs. The high aluminum coverage ($\sim$70%) of this device allows for the discrimination of surface events and separation of events occurring near the center of the detector from those near the edge. We use this discrimination ability to show that dark events seen in previous detectors of a similar design are likely dominated by charge leakage along the side wall of the device. We saw only a small reduction in dark event rate with this biasing scheme, further suggesting that sidewall and edge-dominated processes are responsible for the majority of these events.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2020

Layout and performance of HPK prototype LGAD sensors for the High-Granularity Timing Detector

The High-Granularity Timing Detector is a detector proposed for the ATLAS Phase II upgrade. The detector, based on the Low-Gain Avalanche Detector (LGAD) technology, will cover the pseudo-rapidity region of 2.4 < |n| < 4.0 with two end caps on each side and a total area of 6.4 m 2 . The timing performance can be improved by implanting an internal gain layer that can produce signals with a fast rising edge. It significantly improves the signal-to-noise ratio. The required average timing resolution per track for a minimum ionizing particle is 30 ps at the start and 50 ps at the end of the HL-LHC operation. This is achieved with several layers of LGAD. The innermost region of the detector would accumulate a 1MeV neutron-equivalent fluence up to 2.5 10 15 n eq /cm 2 including a safety factor of 1.5 before being replaced during the scheduled shutdowns. The addition of this new detector is expected to play an important role in the mitigation of high pile-ups at the HL-LHC. The layout and performance of the various versions of LGAD prototypes produced by Hamamatsu (HPK) have been studied by the ATLAS Collaboration. The breakdown voltages, depletion voltages, inter-pad gaps, collected charge as well as the time resolution have been measured and the production yield of large size sensors has been evaluated.

47 OTHER INSTRUMENTATION↗