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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

An Oxygen‐Scavenger Sulfide Coating Enabling Long‐Term Stable Nickel‐Rich Cathodes

Oxygen release is a major issue associated with layer-structured metal oxide cathodes in lithium batteries, which can further cause a series of problems, such as irreversible phase transition, microcracking, and electrolyte decomposition. Eventually, these issues jointly result in cell performance degradation and safety hazards. Thus, it is very significant to tackle oxygen release for achieving long-term stable cyclability, but very challenging. Although intensive efforts have been invested to date, there still lacks a feasible solution. In this study, nanoscale ZrS 2 coatings are applied on prefabricated LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cathodes directly via atomic layer deposition (ALD). Very encouragingly, we reveal that this ALD-deposited conformal ZrS 2 nanocoating can serve as an exceptional oxygen scavenger and then convert into a stable sulfate (Zr(SO 4 ) 2 ) coating. Such an in situ conversion is very beneficial and effective for protecting the electrolyte from decomposition. In addition, the resultant Zr(SO 4 ) 2 coating further inhibits undesirable reactions, stabilizes the interface between NMC811 and the electrolyte, suppresses microcracking, mitigates transition metal dissolution, and maintains the structural stability of the NMC811 cathode. Consequently, the ZrS 2 -coated NMC811 cathode has demonstrated extraordinary performance. Thus, this study advances the understanding of interface engineering while paving a new technical pathway for commercializing NMC811 cathodes.

Nickel-rich cathodes↗
DOE OSTI2020

Comprehensive characterization of hepatocyte-derived extracellular vesicles identifies direct miRNA-based regulation of hepatic stellate cells and DAMP-based hepatic macrophage IL-1ß and IL-17 upregulation in alcoholic hepatitis mice.

Extracellular vesicles (EVs) have been growingly recognized as biomarkers and mediators of alcoholic liver disease (ALD) in human and mice. Here we characterized hepatocyte-derived EVs (HC-EVs) and their cargo for their biological functions in a novel murine model that closely resembles liver pathology observed in patients with alcoholic hepatitis (AH), the most severe spectrum of ALD. The number of circulating EVs and HC-EVs were significantly increased by 10-fold in AH mice compared to control mice. The miRNA(miR)-seq analysis detected 20 up-regulated and 4 down-regulated miRNAs (P < 0.001-0.05) in AH-HC-EVs. Treatment of murine primary hepatic stellate cells (HSCs) with AH-HC-EVs induced ?-SMA (P < 0.05) and Col1a1 (P < 0.001). Smad7, Nr1d2, and Rora genes which regulate HSC activation were predicted targets of 17 miRs up-regulated in AH-HC-EVs. Among them were miR-27a and miR-181 which upon transfection in HSCs, repressed Nr1d2, the HSC quiescence marker. AH-HC-EVs were also enriched in organelle proteins and mitochondrial DNA (10-fold, P < 0.05) and upregulated IL-1??and IL-17 production by hepatic macrophages (HMs) from AH mice in a TLR9-dependent manner. These results demonstrate HC-EV release is intensified in AH and suggest that AH-HC-EVs orchestrate liver fibrogenesis by directly targeting HSC quiescence transcripts via a unique set of miRNAs and by amplifying HSC activation via DAMP-based induction of profibrogenic IL-1? and IL-17 by HMs.

AH, hepatocyte-derived EVs, miRNAs, DAMPs, HSC act↗
DOE OSTI2016

Synthesis of Highly Dispersed and Highly Stable Supported Au–Pt Bimetallic Catalysts by a Two-Step Method

Highly dispersed and highly stable supported bimetallic catalysts were prepared using a two-step process. Pt nanoparticles (NPs) were first deposited on porous γ-Al2O3 particles by atomic layer deposition (ALD). Au NPs were synthesized by using gold(III) chloride as the Au precursor, and then immobilized on ALD Pt/γ-Al2O3 particles. The Au–Pt bimetallic catalysts were highly active and highly stable in a vigorously stirred liquid phase reaction of glucose oxidation.

Wang, Xiaofeng↗
DOE OSTI2016

Fourier transform infrared spectroscopy measurements of multi-phonon and free-carrier absorption in ZnO

Fourier transform infrared (FTIR) measurements were carried out on thin films and bulk single crystals of ZnO over a wide temperature range to study the free-carrier and multi-phonon infrared absorptions and the effects of hydrogen incorporation on these properties. Aluminum-doped ZnO thin films were deposited on quartz substrates using atomic-layer deposition (ALD) and sol–gel methods. Hall-effect measurements showed that the ALD films have a resistivity of ρ = 1.11 × 10 –3 Ω cm, three orders of magnitude lower than sol–gel films (ρ = 1.25 Ω cm). This result is consistent with the significant difference in their free-carrier absorption as revealed by FTIR spectra obtained at room temperature. By reducing the temperature to 80 K, the free carriers were frozen out, and their absorption spectrum was suppressed. From the FTIR measurements on ZnO single crystals that were grown by the chemical vapor transport method, we identified a shoulder around 3350 cm –1 and associated it with the presence of two or more hydrogen ions in a Zn vacancy. After reducing the hydrogen level in the crystal, the measurements revealed the multi-phonon absorption of ZnO in the range of 700–1200 cm –1 . Furthermore, this study shows that the multi-phonon absorption bands can be completely masked by the presence of a large concentration of hydrogen in the crystals.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Amorphous transparent conducting oxides in context: Work function survey, trends, and facile modification

The work functions of various amorphous and crystalline transparent conducting oxides (TCO5) were measured using Kelvin probe. The films, made by pulsed laser deposition, exhibited varying work functions dependent on the composition and deposition parameters. Tin oxide showed the largest work functions of the oxides measured, while zinc oxide showed the lowest. Binary and ternary combinations of the basis TCOs showed intermediate work functions dependent on the endpoint components. Amorphous TCO5, important in OPV and other technological applications, exhibited similar work functions to their crystalline counterparts. UV/ozone treatment of TCOs temporarily increased the work function, consistent with proposed defect mechanisms associated with near-surface changes in carrier content and Fermi level. Finally, a method for facile adjustment of the work function of commercial TCOs by atomic layer deposition (ALD) capping layers was presented, illustrated by the growth of zinc oxide layers on commercial crystalline ITO films.

Yeh, T. C.↗
DOE OSTI2019

Confined seeds derived sodium titanate/graphene composite with synergistic storage ability toward high performance sodium ion capacitors

Sodium ion capacitors (SICs) are increasingly being focused, due to the feature of high energy/power densities derived from the integrated energy storage mechanisms, as well as the ubiquitous sodium sources. Practical anodes with exceptional rate capability can circumvent the kinetic mismatch with cathode, boosting energy/power metrics. Herein, a Na 2 Ti 7 O 15 nanowire/graphene anode is synthesized through an atomic layer deposition (ALD) seeding technique, by which the confined seeds enable Na 2 Ti 7 O 15 with ultra-high aspect ratio and interweaved structure with graphene nanosheets. The composite delivers a superior rate capability of 60 mAh g –1 at a high rate of 17.7 A g –1 , and an exceptional cyclic stability of 90% retention after 10 000 cycles even at 8.85 Ag –1 . It is demonstrated that the morphology, graphene platform, intrinsically low energy diffusion barrier of Na 2 Ti 7 O 15 , and associated reaction mechanism synergize the electron transport, sodium ion migration, and surface capacitive contribution, giving rise to such a decent electrochemical performance. The SICs deliver high energy/power densities (82.7 Wh kg –1 /97.5 W kg –1 , 25 kW kg –1 with 16 Wh kg –1 retained), proving a promise particularly at extremely fast charge/discharge condition. The proposed ALD seeding technique can be developed into a technical strategy for synthesizing high performance energy storage materials.

25 ENERGY STORAGE↗
DOE OSTI2018

Atomic layer deposition of Pt@CsH 2 PO 4 for the cathodes of solid acid fuel cells

Atomic layer deposition (ALD) has been used to apply continuous Pt films on powders of the solid acid CsH 2 PO 4 (CDP), in turn, used in the preparation of cathodes in solid acid fuel cells (SAFCs). The film deposition was carried out at 150 °C using trimethyl(methylcyclopentadienyl)platinum (MeCpPtMe 3 ) as the Pt source and ozone as the reactant for ligand removal. Chemical analysis showed a Pt growth rate of 0.09 ± 0.01 wt%/cycle subsequent to an initial nucleation delay of 84 ± 20 cycles. Electron microscopy revealed the contiguous nature of the films prepared using 200 or more cycles. The cathode overpotential (0.48 ± 0.02 V at a current density of 200 mA/cm 2 ) was independent of Pt deposition amount beyond the minimum required to achieve these continuous films. The cell electrochemical characteristics were moreover extremely stable with time, with the cathode overpotentials increasing by no more than 10 mV over a 100 h period of measurement. So, ALD holds promise as an effective tool in the preparation of SAFC cathodes with high activity and excellent stability.

25 ENERGY STORAGE↗
DOE OSTI2021

Long-life LiNi 0.5 Mn 1.5 O 4 /graphite lithium-ion cells with an artificial graphite-electrolyte interface

The high operating voltage of a spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode leads to electrolyte decomposition and accelerated deterioration of the electrode/electrolyte interface in lithium-ion cells. Aggressive side reactions prevent long-term cycling and hinder its practical application. Advanced characterization shows that the high-voltage operation makes the graphite anode react with the electrolyte, particularly with the lithium salt in the electrolyte, resulting in massive active lithium inventory loss and capacity fade. The side reactions at the graphite are identified as the main culprit for the LNMO/graphite full cell decay. Here, we demonstrate that an artificial solid-electrolyte interface layer consisting of an ultra-thin Al 2 O 3 film, generated via atomic layer deposition (ALD) at the graphite surface, can successfully isolate the graphite from the electrolyte and inhibit the undesired reactions. Consequently, the capacity and cycling stability of the LNMO/graphite cell are drastically improved. After 300 cycles, the capacity retention of LNMO/graphite cell increases from 57.7% to 98.6% with the ALD-coated graphite. Furthermore, our findings provide valuable insights into the LNMO/graphite cell degradation and suggest a simple and robust, yet highly effective, approach for the practical viability of high-voltage lithium-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2022

High-performance LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathode by nanoscale lithium sulfide coating via atomic layer deposition

The commercialization of nickel-rich LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage. To address these issues, surface modification has been well-recognized as an effective strategy. Different from the coatings reported in literature to date, in this work, we for the first time report a sulfide coating, amorphous Li 2 S via atomic layer deposition (ALD). Here, our study revealed that the conformal nano-Li 2 S coating shows exceptional protection over the NMC811 cathodes, accounting for the dramatically boosted capacity retention from ~11.6% to ~71% and the evidently mitigated voltage reduction from 0.39 to 0.18 V after 500 charge–discharge cycles. In addition, the Li 2 S coating remarkably improved the rate capability of the NMC811 cathode. Our investigation further revealed that all these beneficial effects of the ALD-deposited nano-Li 2 S coating lie in the following aspects: (i) maintain the mechanical integrity of the NMC811 electrode; (ii) stabilize the NMC electrode/electrolyte interface; and (iii) suppress the irreversible phase transition of NMC structure. Particularly, this study also has revealed that the nano-Li 2 S coating has played some unique role not associated with traditional non-sulfide coatings such as oxides. In this regard, we disclosed that the Li 2 S layer has reacted with the released O 2 from the NMC lattices, and thereby has dramatically mitigated electrolyte oxidation and electrode corrosion. Thus, this study is significant and has demonstrated that sulfides may be an important class of coating materials to tackle the issues of NMCs and other layered cathodes in lithium batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2018

3D self-supported FeOP film on nickel foam as a highly active bifunctional electrocatalyst for urea-assisted overall water splitting

Highlights: • ALD FeO{sub x} is firstly used to synthesize the amorphous FeOP composite. • The urea oxidation (UOR) is used for Ienergy-intensive hydrogen production. • Highly porous carbon layer is tightly connected with conductive graphene sheets. • High UOR activity with a low potential of 1.34 V (vs. RHE) at 10 mA cm{sup −2}. • The superior bifunctional activity of the FeOP/NF for water-splitting. - Abstract: Replacement of oxygen evolution (OER) by the more readily oxidized urea is considered to be a promising strategy for electrocatalytic water-splitting. In this work, we report a FeOP film on nickel foam (FeOP/NF) via atomic layer deposition (ALD) of iron oxide and a subsequent phosphonation process, which acts as a superior bifunctional electrocatalyst for both urea evolution reaction (UOR) and hydrogen evolution reaction (HER). Benefiting from the synergetic effects, the FeOP/NF exhibits a low potential of 1.34 V (vs. RHE) at 10 mA cm{sup −2} and a low Tafel slope of 57.2 mV dec{sup −1} for UOR. Combined with the high HER activity of FeOP/NF, the urea-based overall water splitting can be performed with an low voltage of 1.43 V to deliver 10 mA cm{sup −2} in 1.0 M KOH with 0.5 M urea, which is 200 mV lower than that for pure water splitting.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Polypyrrole nanowires coated with a hollow shell for enhanced electrochemical performance

Highlights: • A hollow shell coated on polypyrrole nanowires is constructed with the assistance of atomic layer deposition (ALD). • Binder-free electrode of holloe core-shell polypyrrole-TiO{sub 2} is obtained • The hollow core-shell nanostructure shows apparent higher capacitance and better cycling stability than the bare nanowires. - Abstract: Conducting polymers are promising electrode materials for electrochemical capacitors, but are suffered from poor cycling stability and relatively low capacitance. Herein, a hollow shell coated on polypyrrole (Ppy) nanowires is designed and constructed with the assistance of atomic layer deposition (ALD). Ppy nanowires are firstly deposited on flexible carbon cloth by electrodeposition, then a thin sacrificial layer of ZnO and a thin shell of TiO{sub 2} are deposited uniformly on the surfaces of the nanowires. After removing the ZnO layer, a nanogap between the Ppy core and TiO{sub 2} shell is formed thus generate a hollow core-shell Ppy-TiO{sub 2} (noted as Ppy·TiO{sub 2}) nanoarray. When tested as supercapacitor electrodes, the hollow core-shell nanostructure shows apparent higher capacitance and better cycling stability than the bare nanowires. Such enhancement is ascribed to the rational hollow structure design that provides enlarged surface areas and enhanced structure stability. Such hollow structure can be extended to other conducting polymers and electrodes for various electrochemical applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2023

Determination of film thicknesses of metal oxides prepared by atomic layer deposition on SBA-15

ZrO 2 and CeO 2 films were grown in SBA-15 by Atomic Layer Deposition (ALD) to loadings of 0.92 g oxide/g SBA-15. Scanning Transmission Electron Microscopy (STEM) with Energy Dispersive Spectra (EDS) showed that the oxides grew uniformly inside the mesopores. Film thicknesses were then analyzed as a function of the number of ALD cycles using three methods: 1) mass changes assuming bulk densities for the films; 2) changes in pore size from Barret-Joyner-Halenda (BJH) analysis with N 2 adsorption isotherms; and 3) small-angle X-ray scattering (SAXS). Film thicknesses assuming bulk densities were between 6 and 8 times smaller than those obtained from BJH analysis. SAXS analysis gave film thicknesses that were approximately twice that obtained from bulk densities. Here, possible explanations of the discrepancies between these methods are discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Electrocatalysts by atomic layer deposition for fuel cell applications

Here, fuel cells are a promising technology solution for reliable and clean energy because they offer high energy conversion efficiency and low emission of pollutants. However, high cost and insufficient durability are considerable challenges for widespread adoption of polymer electrolyte membrane fuel cells (PEMFCs) in practical applications. Current PEMFCs catalysts have been identified as major contributors to both the high cost and limited durability. Atomic layer deposition (ALD) is emerging as a powerful technique for solving these problems due to its exclusive advantages over other methods. In this review, we summarize recent developments of ALD in PEMFCs with a focus on design of materials for improved catalyst activity and durability. New research directions and future trends have also been discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Manipulation of an ionic and electronic conductive interface for highly-stable high-voltage cathodes

A stable and conductive interface is one of the decisive factors in manipulating the performance of high voltage LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode for Li-ion batteries. Herein, a hybrid Li 3 PO 4 -TiO 2 coating layer is designed as an interfacial material via controllable atomic layer deposition (ALD) on LNMO. The coating acts not just as a physical barrier to prevent the side-reactions between cathode and electrolyte at high voltage, more importantly, the hybrid coating material improves both interfacial ionic and electronic conductivities to build facile Li-ion and electron diffusion pathways for LNMO. The optimized LNMO demonstrates improved rate capability and long-life stability. The capacity retention is 81.2% comparing with 47.4% of bare LNMO at 0.5C after 300 cycles. Detailed surface structural evolution is studied via X-ray absorption near edge spectroscopy and transmission electron microscopy. Furthermore, this work provides new insights of hybrid interfacial design via ALD and promotes novel electrode architectures for batteries.

25 ENERGY STORAGE↗
DOE OSTI2023

Multicolored microwave absorbers with dynamic frequency modulation

Microwave-absorbing materials are extensively used in intelligent electronic devices and stealth technologies where the ability to dynamically adjust microwave-absorbing capacity in response to specific requirements is vitally important. Herein, we report a new approach for constructing dynamically tunable microwave absorbers with ultrawide tunable frequency ranges that are simultaneously endowed with vibrant structural colors. Here, the methodology produces structural colors and adjusts absorption properties by constructing ZnO coatings with precisely adjustable thicknesses on a polypyrrole/melamine foam (PPy/MF) surface by atomic layer deposition (ALD) in conjunction with a pressure-driven strategy that regulates the compression ratio. The electrical conductivity, electromagnetic parameters, thickness, and pore size of the ZnO-coated PPy/MF (ZnO/PPy/MF) are effectively adjusted, and simply applying external pressure widens the tunable frequency range and the effective absorption bandwidth. As a result, the effective absorption frequency of ZnO/PPy/MF is dynamically adjustable from the S band to the Ku band, thereby covering 94.3% of the entire microwave spectrum. Moreover, the brilliant and uniform structural colors of ZnO/PPy/MF, which span various color categories, are precisely regulated by tuning the thickness of the ZnO coating by adjusting the number of ALD cycles. ZnO/PPy/MF is strongly hydrophobic, which endows it with remarkable self-cleaning properties. Therefore, ZnO/PPy/MF provides a conceptually novel platform for the development of next-generation smart microwave-absorbing materials due to its integrated dynamic frequency-regulating ability, brilliant structural coloration, and self-cleaning features.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Investigating the effect of aluminum oxide fixed charge on Schottky barrier height in molybdenum oxide-based selective contacts

A tunneling atomic layer deposited (ALD) AlO x layer was inserted in a Si|SiO x |AlO x |MoO x |metal tunnel diode structure to investigate the impact of fixed interface charge on Schottky barrier height. ALD AlO x provides a synthesis-tunable fixed charge and can provide excellent field effect passivation at the SiO x |AlO x interface. A large (>1 × 10 12 q.cm –2 ) negative fixed charge density was expected to decrease Schottky barrier height on p-type silicon and increase Schottky barrier height on n-type silicon by up to 0.4 eV based on an electrostatic model. Fixed charge density and interface trap state density were measured using a thick layer of AlO x in metal oxide semiconductor capacitor structures (MOSCAPs); Schottky barrier height and specific contact resistivity were measured using a tunneling-active layer of AlO x in contacted structures with MoO x . In some samples, HfO x interface layers were inserted between AlO x and silicon to quench the fixed negative charge. The Schottky barrier height was found to vary with processing conditions but did not have a strong correlation with expected fixed charge density. Here, while fixed charge may play a role in determining the Schottky barrier height, other parameters also have significant affect. Further work is needed to minimize contact resistivity and elucidate other factors impacting the Schottky barrier height.

14 SOLAR ENERGY↗
DOE OSTI2017

Synchrotron X-ray studies of model SOFC cathodes, part II: Porous powder cathodes

Infiltrated La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) sintered porous powder cathodes for solid oxide fuel cells have been investigated by synchrotron ultra-small angle x-ray scattering (USAXS). Here, we demonstrated that atomic layer deposition (ALD) is the method for a uniform coating and liquid-phase infiltration for growing nanoscale particles on the porous LSCF surfaces. The MnO infiltrate, grown by ALD, forms a conformal layer with a uniform thickness throughout the pores evidenced by USAXS thickness fringes. The La 0.6 Sr 0.4 CoO 3 (LSC) and La 2 Zr 2 O 7 (LZO) infiltrates, grown by liquid-phase infiltration, were found to form nanoscale particles on the surfaces of LSCF particles resulting in increased surface areas. In conclusion, impedance measurements suggest that the catalytic property of LSC infiltrate, not the increased surface area of LZO, is important for increasing oxygen reduction activities.

36 MATERIALS SCIENCE↗