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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 OSTI2020

Consolidating Lithiothermic-Ready Transition Metals for Li2S-Based Cathodes

Li 2 S holds a promising role as a high-capacity Li-containing cathode, circumventing use of metallic lithium in constructing next-generation batteries to replace current Li-ion batteries. However, progress of Li 2 S cathode has been plagued by its intrinsic drawbacks, including high activation potentials, poor rate performance, and rapid capacity fading during long cycling. In this work, a series of Li 2 S/transition metal (TM) nanocomposites are synthesized via a lithiothermic reduction reaction, and it is realized that the presence of TMs in Li 2 S matrix can transform electrochemical behaviors of Li 2 S. On the one hand, the incorporation of W, Mo, or Ti greatly increases electronic and ionic conductivity of Li 2 S composites and inhibits the polysulfide dissolution via the TM—S bond, effectively addressing the drawbacks of Li 2 S cathodes. In particular, Li 2 S/W and Li 2 S/Mo exhibit the highest ionic conductivity of solid-phase Li-ion conductors ever-reported: 5.44 × 10 –2 and 3.62 × 10 –2 S m –1 , respectively. On the other hand, integrating Co, Mn, and Zn turns Li 2 S into a prelithiation agent, forming metal sulfides rather than S 8 after the full charge. These interesting findings may shed light on the design of Li 2 S-based cathode materials.

25 ENERGY STORAGE↗
DOE OSTI2021

A Micrometer‐Sized Silicon/Carbon Composite Anode Synthesized by Impregnation of Petroleum Pitch in Nanoporous Silicon

Porous silicon (Si)/carbon nanocomposites have been extensively explored as a promising anode material for high-energy lithium (Li)-ion batteries (LIBs). However, shrinking of the pores and sintering of Si in the nanoporous structure during fabrication often diminishes the full benefits of nanoporous Si. Herein, a scalable method is reported to preserve the porous Si nanostructure by impregnating petroleum pitch inside of porous Si before high-temperature treatment. The resulting micrometer-sized Si/C composite maintains a desired porosity to accommodate large volume change and high conductivity to facilitate charge transfer. It also forms a stable surface coating that limits the penetration of electrolyte into nanoporous Si and minimizes the side reaction between electrolyte and Si during cycling and storage. A Si-based anode with 80% of pitch-derived carbon/nanoporous Si enables very stable cycling of a Si||Li(Ni0.5Co0.2Mn0.3)O 2 (NMC532) battery (80% capacity retention after 450 cycles). It also leads to low swelling in both particle and electrode levels required for the next generation of high-energy LIBs. In conclusion, the process also can be used to preserve the porous structure of other nanoporous materials that need to be treated at high temperatures.

anode materials↗
DOE OSTI2022

Controlling Mineralization with Protein–Functionalized Peptoid Nanotubes

Sequence-defined foldamers that self-assemble into well-defined architectures are promising scaffolds to template inorganic mineralization. However, it has been challenging to achieve robust control of nucleation and growth without sequence redesign or extensive experimentation. Here, peptoid nanotubes functionalized with a panel of solid-binding proteins are used to mineralize homogeneously distributed and monodisperse anatase nanocrystals from the water-soluble TiBALDH precursor. Crystallite size is systematically tuned between 1.4 and 4.4 nm by changing protein coverage and the identity and valency of the genetically engineered solid-binding segments. The approach is extended to the synthesis of gold nanoparticles and, using a protein encoding both material-binding specificities, to the fabrication of titania/gold nanocomposites capable of photocatalysis under visible-light illumination. Here, beyond uncovering critical roles for hierarchical organization and denticity on solid-binding protein mineralization outcomes, the strategy described herein should prove valuable for the fabrication of hierarchical hybrid materials incorporating a broad range of inorganic components.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Ultrastrong Ionotronic Films Showing Electrochemical Osmotic Actuation

Abstract A multifunctional soft material with high ionic and electrical conductivity, combined with high mechanical properties and the ability to change shape can enable bioinspired responsive devices and systems. The incorporation of all these characteristics in a single material is very challenging, as the improvement of one property tends to reduce other properties. Here, a nanocomposite film based on charged, high‐aspect‐ratio 1D flexible nanocellulose fibrils, and 2D Ti 3 C 2 T x MXene is presented. The self‐assembly process results in a stratified structure with the nanoparticles aligned in‐plane, providing high ionotronic conductivity and mechanical strength, as well as large water uptake. In hydrogel form with 20 wt% liquid, the electrical conductivity is over 200 S cm −1 and the in‐plane tensile strength is close to 100 MPa. This multifunctional performance results from the uniquely layered composite structure at nano‐ and mesoscales. A new type of electrical soft actuator is assembled where voltage as low as ±1 V resulted in osmotic effects and giant reversible out‐of‐plane swelling, reaching 85% strain.

Chemistry↗
DOE OSTI2023

Simultaneous Enhancement of Efficiency And Operational-Stability of Mesoscopic Perovskite Solar Cells via Interfacial Toughening

The combined effects of compact TiO 2 (c-TiO 2 ) electron-transport layer (ETL) are investigated without and with mesoscopic TiO 2 (m-TiO 2 ) on top, and without and with an iodine-terminated silane self-assembled monolayer (SAM), on the mechanical behavior, opto–electronic properties, photovoltaic (PV) performance, and operational-stability of solar cells based on metal-halide perovskites (MHPs). The interfacial toughness increases almost threefold in going from c-TiO 2 without SAM to m-TiO 2 with SAM. This is attributed to the synergistic effect of the m-TiO 2 /MHP nanocomposite at the interface and the enhanced adhesion afforded by the iodine-terminated silane SAM. The combination of m-TiO 2 and SAM also offers a significant beneficial effect on the photocarriers extraction at the ETL/MHP interface, resulting in perovskite solar cells (PSCs) with power-conversion efficiency (PCE) of over 24% and 20% for 0.1 and 1 cm 2 active areas, respectively. These PSCs also have exceptionally long operational stability lives extrapolated T80 (duration at 80% initial PCE retained) is ≈18 000 and 10 000 h for 0.1 and 1 cm 2 active areas, respectively. In conclusion, postmortem characterization and analyses of the operational-stability-tested PSCs are performed to elucidate the possible mechanisms responsible for the long operational-stability.

14 SOLAR ENERGY↗
DOE OSTI2020

Graphene K‐Tape Meshes for Densely Distributed Human Motion Monitoring

Abstract Wearable sensors that measure parameters associated with physical activity and bodily motions have been regarded as an indispensable tool for assessing personal wellness. Recent advances in nanocomposite strain sensors have been successfully used for monitoring skin strains and other strain‐derived physiological parameters. This study complements the existing body of work and presents a flexible, self‐adhering, fabric‐based wearable sensor for measuring skin strains and human motions. Graphene nanosheet thin films are directly spray‐coated onto kinesiology tape (K‐Tape) to obtain a self‐adhering strain sensor of high sensitivity and linearity. Their stable sensing performance and high repeatability are verified, while human subject tests confirm that they adequately capture muscle engagement during functional movements. In addition, densely distributed strain monitoring can be achieved using an electrical impedance tomography measurement approach and algorithm. Spatial strain sensing is successfully demonstrated using a single strip of piezoresistive K‐Tape, as well as when a K‐Tape network or mesh pattern is formed. The results show promise for using graphene K‐Tape meshes to measure how specific major muscle groups engage during different physical activities.

Lin, Yun‐An↗
DOE OSTI2022

Elucidating the Synergic Effect in Nanoscale MoS 2 /TiO 2 Heterointerface for Na‐Ion Storage

Abstract Interface engineering in electrode materials is an attractive strategy for enhancing charge storage, enabling fast kinetics, and improving cycling stability for energy storage systems. Nevertheless, the performance improvement is usually ambiguously ascribed to the “synergetic effect”, the fundamental understanding toward the effect of the interface at molecular level in composite materials remains elusive. In this work, a well‐defined nanoscale MoS 2 /TiO 2 interface is rationally designed by immobilizing TiO 2 nanocrystals on MoS 2 nanosheets. The role of heterostructure interface between TiO 2 and MoS 2 by operando synchrotron X‐ray diffraction (sXRD), solid‐state nuclear magnetic resonance, and density functional theory calculations is investigated. It is found that the existence of a hetero‐interfacial electric field can promote charge transfer kinetics. Based on operando sXRD, it is revealed that the heterostructure follows a solid‐solution reaction mechanism with small volume changes during cycling. As such, the electrode demonstrates ultrafast Na + ions storage of 300 mAh g −1 at 10 A g −1 and excellent reversible capacity of 540 mAh g −1 at 0.2 A g −1 . This work provides significant insights into understanding of heterostructure interface at molecular level, which suggests new strategies for creating unconventional nanocomposite electrode materials for energy storage systems.

25 ENERGY STORAGE↗
DOE OSTI2025

Rapid Synthesis of Carbon‐Supported Ru‐RuO₂ Heterostructures for Efficient Electrochemical Water Splitting

Abstract Development of high‐performance electrocatalysts for water splitting is crucial for a sustainable hydrogen economy. In this study, rapid heating of ruthenium(III) acetylacetonate by magnetic induction heating (MIH) leads to the one‐step production of Ru‐RuO₂/C nanocomposites composed of closely integrated Ru and RuO₂ nanoparticles. The formation of Mott‐Schottky heterojunctions significantly enhances charge transfer across the Ru‐RuO 2 interface leading to remarkable electrocatalytic activities toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1 m KOH. Among the series, the sample prepares at 300 A for 10 s exhibits the best performance, with an overpotential of only −31 mV for HER and +240 mV for OER to reach the current density of 10 mA cm⁻ 2 . Additionally, the catalyst demonstrates excellent durability, with minimal impacts of electrolyte salinity. With the sample as the bifunctional catalysts for overall water splitting, an ultralow cell voltage of 1.43 V is needed to reach 10 mA cm⁻ 2 , 160 mV lower than that with a commercial 20% Pt/C and RuO₂/C mixture. These results highlight the significant potential of MIH in the ultrafast synthesis of high‐performance catalysts for electrochemical water splitting and sustainable hydrogen production from seawater.

Pan, Dingjie [Department of Chemistry and Biochemi↗
DOE OSTI2023

Interface Design for High‐Performance All‐Solid‐State Lithium Batteries

All‐solid‐state batteries suffer from high interface resistance and lithium dendrite growth leading to low Li plating/stripping Coulombic efficiency (CE) of <90% and low critical current density at high capacity. Here, in this work, both challenges are simultaneously addressed and the Li plating/stripping CE is significantly increased to 99.6% at 0.2 mA cm −2 /0.2 mAh cm −2 , and critical current density (CCD) of > 3.0 mA cm −2 /3.0 mAh cm −2 by inserting a mixed ionic‐electronic conductive (MIEC) and lithiophobic LiF‐C‐Li 3 N‐Bi nanocomposite interlayer between Li 6 PS 5 Cl electrolyte and Li anode. The highly lithiophobic LiF‐C‐Li 3 N‐Bi interlayer with high ionic conductivity (10 −5 S cm −1 ) and low electronic conductivity (3.4×10 −7 S cm −1 ) enables Li to plate on the current collector (CC) surface rather than on Li 6 PS 5 Cl surface avoiding Li 6 PS 5 Cl electrolyte reduction. During initial Li plating on CC, Li penetrates into porous LiF‐C‐Li 3 N‐Bi interlayer and lithiates Bi nanoparticles into Li 3 Bi. The lithiophilic Li 3 Bi and Li 3 N nanoparticles in LiF‐C‐Li 3 N‐Li 3 Bi sub‐interlayer will move to CC along with plated Li, forming LiF‐C/Li 3 N‐Li 3 Bi lithiophobic/lithiophilic sublayer during the following Li stripping. This interlayer enables Co 0.1 Fe 0.9 S 2 /Li 6 PS 5 Cl/Li cell with an areal capacity of 1.4 mAh cm −2 to achieve a cycle life of >850 cycles at 150 mA g −1 . The lithiophobic/lithiophilic interlayer enables solid‐state metal batteries to simultaneously achieve high energy and long cycle life.

25 ENERGY STORAGE↗
DOE OSTI2020

Tunable Electromechanical Liquid Crystal Elastomer Actuators

Liquid crystal elastomers (LCE) are soft materials which anisotropically shape morph in response to external stimuli. Herein, a method to produce large‐area carbon nanotube–LCE nanocomposite films with exceptional electrostrictive properties is examined. A methodology to produce telechelic precursor oligomeric composites at scale (>100 g) is presented along with the continuous casting and photocuring process. The carbon nanotubes are well‐aligned and well‐dispersed in the films, which exhibit exceptional anisotropic thermomechanical, optical, and thermal shape change characteristics. When an electric field is applied through the film thickness, the material quickly and reversibly contracts along the alignment direction. As an example, a compliant carbon nanotube–LCE film contracts >4% against a 140 kPa load, roughly comparable to the blocking force of many natural muscular tissues. Furthermore, it is demonstrated that this tunable contraction is dependent upon the electric field strength, and that the contraction mimics the form function of the input electric field (e.g., a sine wave). These compliant actuators are excellent candidates for incorporation into soft and/or biological systems.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Flame retardant biogenic building insulation materials from hemp fiber

Biogenic thermal insulation materials are in high demand because of its carbon-sequestration nature. However, high flammability, moisture condensation, and relatively high thermal conductivity of biogenic material are major concerns for sustainable building applications. In this study, we report the fire-retardant cellulose xerogel insulation nanocomposites derived from hemp fiber recycling and silica xerogel, in which the boric acid treatment improves its fire retardancy. The as-prepared materials show a low thermal conductivity of 31.3 mW/m K, high flexural modulus of 665 MPa, hydrophobicity with the water contact angle of 115°, and fire retardancy with 30% weight loss over a period of burning time 10 min. Overall, this work provides an effective method for the synthesis of fire-retardant biogenic thermal insulation materials and shows a promising way for next-generation bio-based insulation materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Porous CeO 2 /CuO Heterostructure for Efficient Hydrogen Evolution Reaction in an Acidic Medium

A composite electrocatalyst CeO 2 /CuO is fabricated for the hydrogen evolution reaction (HER) via a simple, facile, one‐step hydrothermal method, using F‐127 as a template and structure directing agent. The prepared composite CeO 2 /CuO shows top‐notch HER activities with a small overpotential of 98 mV at 10 mA cm −2 and just 160 mV overpotential to attain a current density of 50 mA cm −2 with good stability for 20 h in an acidic medium. The enhanced catalytic activities of CeO 2 /CuO nanocomposite are attributed to their synergetic interface interaction, which lead to improved conductivity, reactive sites, and oxygen vacancies in their lattices. This study aims to advance the development of earth‐abundant transition metal oxides–based electrocatalysts as economical, durable, and efficient HER electrocatalysts to replace noble metal–based materials in the future.

Chemistry↗
DOE OSTI2020

Large-Scale Plasmonic Hybrid Framework with Built-In Nanohole Array as Multifunctional Optical Sensing Platforms

Light coupling with patterned subwavelength hole arrays induces enhanced transmission supported by the strong surface plasmon mode. In this work, a nanostructured plasmonic framework with vertically built-in nanohole arrays at deep-subwavelength scale (6 nm) is demonstrated using a two-step fabrication method. The nanohole arrays are formed first by the growth of a high-quality two-phase (i.e., Au–TiN) vertically aligned nanocomposite template, followed by selective wet-etching of the metal (Au). Such a plasmonic nanohole film owns high epitaxial quality with large surface coverage and the structure can be tailored as either fully etched or half-way etched nanoholes via careful control of the etching process. The chemically inert and plasmonic TiN plays a role in maintaining sharp hole boundary and preventing lattice distortion. Optical properties such as enhanced transmittance and anisotropic dielectric function in the visible regime are demonstrated. Numerical simulation suggests an extended surface plasmon mode and strong field enhancement at the hole edges. Furthermore, two demonstrations, including the enhanced and modulated photoluminescence by surface coupling with 2D perovskite nanoplates and the refractive index sensing by infiltrating immersion liquids, suggest the great potential of such plasmonic nanohole array for reusable surface plasmon-enhanced sensing applications.

42 ENGINEERING↗
DOE OSTI2023

Reversible Iron Oxyfluoride (FeOF)–Graphene Composites as Sustainable Cathodes for High Energy Density Lithium Batteries

Two large barriers are impeding the wide implementation of electric vehicles, namely driving-range and cost, primarily due to the low specific energy and high cost of mono-valence cathodes used in lithium-ion batteries. Iron is the ideal element for cathode materials considering its abundance, low cost and toxicity. However, the poor reversibility of (de)lithiation and low electronic conductivity prevent iron-based high specific energy multi-valence conversion cathodes from practical applications. In this work, a sustainable FeOF nanocomposite is developed with extraordinary performance. The specific capacity and energy reach 621 mAh g –1 and 1124 Wh kg –1 with more than 100 cycles, which triples the specific capacity, and doubles the specific energy of current mono-valence intercalation LiCoO 2 . This is the result of an effective approach, combing the nanostructured FeOF with graphene, realized by making the (de)lithiation reversible by immobilizing FeOF nanoparticles and the discharge products over the graphene surface and providing the interparticle electric conduction. Importantly, it demonstrates that introducing small amount of graphene can create new materials with desired properties, opening a new avenue for altering the (de)lithiation process. Finally, such extraordinary performance represents a significant breakthrough in developing sustainable conversion materials, eventually overcoming the driving range and cost barriers.

25 ENERGY STORAGE↗
DOE OSTI2024

TiN‐Au/HfO 2 ‐Au Multilayer Thin Films with Tunable Hyperbolic Optical Response

Abstract Hyperbolic metamaterials (HMM) possess significant anisotropic physical properties and tunability and thus find many applications in integrated photonic devices. HMMs consisting of metal and dielectric phases in either multilayer or vertically aligned nanocomposites (VAN) form are demonstrated with different hyperbolic properties. Herein, self‐assembled HfO 2 ‐Au/TiN‐Au multilayer thin films, combining both the multilayer and VAN designs, are demonstrated. Specifically, Au nanopillars embedded in HfO 2 and TiN layers forming the alternative layers of HfO 2 ‐Au VAN and TiN‐Au VAN. The HfO 2 and TiN layer thickness is carefully controlled by varying laser pulses during pulsed laser deposition (PLD). Interestingly, tunable anisotropic physical properties can be achieved by adjusting the bi‐layer thickness and the number of the bi‐layers. Type II optical hyperbolic dispersion can be obtained from high layer thickness structure (e.g., 20 nm), while it can be transformed into Type I optical hyperbolic dispersion by reducing the thickness to a proper value (e.g., 4 nm). This new nanoscale hybrid metamaterial structure with the three‐phase VAN design shows great potential for tailorable optical components in future integrated devices.

Chemistry↗
DOE OSTI2020

A novel battery scheme: Coupling nanostructured phosphorus anodes with lithium sulfide cathodes

Lithium-ion batteries are approaching their theoretical limit and can no longer keep up with the increasing demands of human society. Lithium-sulfur batteries, with a high theoretical specific energy, are promising candidates for next generation energy storage. However, the use of Li metal in Li-S batteries compromises both safety and performance, enabling dendrite formation and causing fast capacity degradation. Previous studies have probed alternative battery systems to replace the metallic Li in Li-S system, such as a Si/Li2S couple, with limited success in performance. Recently, there is a focus on red P as a favorable anode material to host Li. In this work, we establish a novel battery scheme by utilizing a P/C nanocomposite anode and pairing it with a Li 2 S coated carbon nanofiber cathode. We find that red P anode can be compatible in ether-based electrolyte systems and can be successfully coupled to a Li 2 S cathode. Our proof of concept full-cell displays remarkable specific capacity, rate and cycling performances. We expect our work will provide a useful alternative system and valuable insight in the quest for next generation energy storage devices.

25 ENERGY STORAGE↗
DOE OSTI2022

Role of interfaces on phase formation during severe plastic deformation

The role of interfaces on phase formation during severe plastic deformation (SPD) was investigated using molecular dynamics simulations. It is found that dilute solute additions that segregate to interphase boundaries, and strengthen them, can greatly extend the solubility limits of the bounding phases at steady state, providing a novel approach to processing nanocomposite alloys by SPD. Here, the results are rationalized in terms of a modified effective temperature model, whereby increasing the interface strength leads to higher effective temperatures and correspondingly to higher solubilities. Comparison of the segregation coefficient at the interphase boundary with solubilities in the bounding phases illustrates the effective temperature model is self-consistent and comprehensive. Past experimental studies on severe plastic deformation are found consistent with these observations.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Rules for the crystallite size and dislocation density evolution in phases during α-ω transformation in Zr under high-pressure and severe plastic flow

The first in-situ X-ray diffraction (XRD) study of the evolution of the crystallite size and dislocation density in phases during plastic strain-induced phase transformation (PT) is performed utilizing α-ω PT in strongly pre-deformed commercially pure Zr as an important example. Rough diamond anvils (rough-DA) are introduced to intensify all occurring processes during heterogeneous compression of Zr in a diamond anvil cell (DAC). The main rule is found that during α-ω PT the crystallite size and dislocation density in ω-Zr depend solely on the volume fraction of ω-Zr and are independent of pressure, plastic strain tensor, its path, and initial nanostructure. Crystallite size in ω-Zr increases from 10 to 60 nm during the PT, while dislocation density reduces from 1.83×10 15 /m 2 to 0.6×10 15 /m 2 . Rough-DA produce a steady nanostructure in α-Zr before PT with smaller crystallite size and larger dislocation density than smooth-DA, leading to a reduction of the minimum pressure for α-ω PT to a record value 0.67 GPa, 9 times smaller than under hydrostatic loading and 5.1 times lower than the phase equilibrium pressure. In addition to strain, the kinetics of strain-induced PT unexpectedly depends on time. Also, strain-controlled part of kinetics is zero order, in contrast to the first-order kinetics with smooth-DA. The obtained results open a new window for understanding the mutual effects of nanostructure evolution and PT during severe plastic flow in various technological and natural processes. In conclusion, they may bring up economic strategies of producing nanocomposites and single-phase nanostructured materials with optimal properties.

Crystalline size↗