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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Novel Superionic Na Conductors for Solid‐State Na batteries: Materials and Interface

This project aims to advance the fundamental understanding on how the cation or anion doping influence on the crystal structure, phase stability and ion transport of novel Na superionic conductors. Specifically, we focus on the Na 3-x A x SbS 4-y X y family solid electrolytes (A: cation dopant, X: anion dopant), a class of promising materials for all-solid-state sodium batteries owing to their high ionic conductivity and compositional tunability. By integrating materials synthesis, neutron scattering, and electrochemical characterization and theoretical simulations, this project sees to elucidate 1) how does the synthesis approaches (solid-state reaction, low-temperature reaction) on the phase purity and doping process; 2) how chemical doping (A: cation dopants such as Sn; X: anion dopants such as Se, F) modulate lattice dynamics and Na+ migration as well as interface stability toward Na metal. Specifically, this project’s proposed technology involves three objectives: (1) synthesize novel Na-ion conductors (anion or cation doped Na 3 SbS 4 ) with high phase purity and examine their structural features (e.g., phase stability); (2) understand Na-ion conductive properties of new Na-ion conductors through a combination of experimental characterizations and theoretical simulations; (3) investigate the interface stability of novel Na superionic conductors with electrode materials in solid-state Na batteries. These objectives will be achieved through combined experimental synthesis/characterizations and computational approaches. The obtained knowledge will provide a comprehensive synthesis-structure-property correlation, enabling the rational design of novel solid-state conductors with excellent conductivity and stability.

25 ENERGY STORAGE↗
DOE OSTI2024

Deconvoluting Effects of Lithium Morphology and SEI Stability at Moderate Current Density Using Interface Engineering

Lithium (Li)-morphology and solid electrolyte interphase (SEI) are among the most significant performance regulators in Li-metal batteries (LMBs). While both Li-morphology and SEI composition play key roles in the cyclability of LMBs, less is understood about the individual contributions of each factor to overall Li reversibility, particularly at a practical current density (1 mA cm −2 ) at which the kinetics of both factors are not naturally separated. Herein, an interface engineering approach is introduced to deconvolute the impacts of Li-morphology and SEI composition on battery performance. By using interfacial nanofilms with differing resistivity (resistive HfO 2 versus conductive ZnO), the morphology of Li is varied, and by virtue of similar acidic character of the nanofilms, the formation of anion-rich SEIs is maintained. It is established that although the surface acidity of the thin films enables preformation of a more anion-rich SEI, it is not preserved after Li plating. It is further shown that resistance-controlled, low-surface-area Li-morphology exhibits up to threefold increase in stable cycle life when tested in multiple electrolytes. Overall, these findings explain why Li-morphological control is more advantageous for performance improvement than preformed SEI modulation due to the inherent challenges in SEI preservation.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Rational Design of Weakly‐Solvating Molecules for Salt‐In‐Pre‐Ionic‐Liquid Electrolytes for Li Metal Batteries

Lithium metal batteries (LMBs) promise step‐changes in energy densities but suffer from poor cycle life due to unstable electrolyte‐lithium interfaces. Conventional carbonate electrolytes exhibit excessive lithium‐ion solvation and low oxidative stability, leading to rapid capacity loss. Herein, we report a rationally designed weakly‐solvating cyclic sulfonamide, 1‐trifluoromethanesulfonyl)amide pyrrolidine (TFMSPyr), which integrates an electron‐withdrawing trifluoromethanesulfonyl functional group at pyrrolidinic‐N. TFMSPyr acts as a pre‐ionic‐liquid solvent that forms intrinsically localized, anion‐dominated solvation, coupling molecular architecture, solvation topology, and transport dynamics. As a result, LiFSI based salt‐in‐pre‐ionic‐liquid (SIPIL) electrolytes exhibit high lithium‐ion transference number, oxidative stability > 5 V versus Li/Li + and anion‐derived solid electrolyte interphases (SEI). Li||Cu cells with SIPIL deliver a first cycle Coulombic efficiency (CE) of ≈ 99% with average CE of 99.2% for 100 cycles, and lithium half‐cells with lithium iron phosphate (LFP) cathode exhibit 82% capacity retention after 400 cycles with CE of 99.98%. In anode‐free full cells, 95% of initial capacity is retained after 63 cycles with an average CE of 99.5%. These results demonstrate that molecular engineering of solvents offers a powerful pathway to stabilize lithium metal interfaces and enable practical Anodeless LMBs.

25 ENERGY STORAGE↗
NASA NTRS1990

The effect of an electric field on the morphological stability of the crystal-melt interface of a binary alloy. III - Weakly nonlinear theory

The effect of a constant electric current on the crystal-melt interface morphology during directional solidification at constant velocity of a binary alloy is considered. A linear temperature field is assumed, and thermoelectric effects and Joule heating are neglected; electromigration and differing electrical conductivities of crystal and melt are taken into account. A two-dimensional weakly nonlinear analysis is carried out to third order in the interface amplitude, resulting in a cubic amplitude equation that describes whether the bifurcation from the planar state is supercritical or subcritical. For wavelengths corresponding to the most dangerous mode of linear theory, the demarcation between supercritical and subcritical behavior is calculated as a function of processing conditions and material parameters. The bifurcation behavior is a sensitive function of the magnitude and direction of the electric current and of the electrical conductivity ratio.

Wheeler, A. A.↗
DOE OSTI2024

Heterogeneous Solid Electrolyte Interphase Interactions Dictate Interface Instability in Sodium Metal Electrodes

Sodium (Na) metal batteries have attracted recent attention due to their low cost and high abundance of Na. However, the advancement of Na metal batteries is impeded due to key challenges such as dendrite growth, solid electrolyte interphase (SEI) fracture, and low Coulombic efficiency. This study examines the coupled electro‐chemo‐mechanical interactions governing the electrodeposition stability and morphological evolution at the Na/electrolyte interface. The SEI heterogeneities influence transport and reaction kinetics leading to the formation of current and stress hotspots during Na plating. Further, it is demonstrated that the heterogeneity‐induced Na metal evolution and its influence on the stress distribution critically affect the mechanical overpotential, contributing to a faster SEI failure. The analysis reveals three distinct failure mechanisms—mechanical, transport, and kinetic—that govern the onset of instabilities at the interface. Finally, a comprehensive comparative study of SEI failure in Na and lithium (Li) metal anodes illustrates that the electrochemical and mechanical characteristics of the SEI are crucial in tailoring the anode morphology and interface stability. This work delineates mechanistic stability regimes cognizant of the SEI attributes and underlying failure modes and offers important guidelines for the design of artificial SEI layers for stable Na metal electrodes.

25 ENERGY STORAGE↗
NASA NTRS1994

Convection and morphological stability during directional solidification

For growth of a vicinal face at constant velocity, the effect of anisotropic interface kinetics on morphological stability is calculated for a binary alloy. The dependence of the interface kinetic coefficient on crystallographic orientation is based on the motion and density of steps. Anisotropic kinetics give rise to traveling waves along the crystal-melt interface, and can lead to a significant enhancement of morphological stability. The stability enhancement increases as the orientation approaches a singular orientation and as the solidification velocity increases. Shear flows interact with the traveling waves and, depending on the direction of the flow, may either stabilize or destabilize the interface. Specific calculations are carried out for germanium-silicon alloys.

Coriell, Sam R.↗
NASA NTRS1988

Nonlinear stability of the dayside cometary ionopause

The MHD stability of the cometary ionopause is investigated by nonlinear analysis, describing that stability in terms of the finite perturbation amplitude of both Kelvin-Helmholtz and Rayleigh-Taylor modes. The evolution of the unstable modes is examined, determining the conditions under which finite amplitude effects are expected to stabilize a growing wave disturbance. The analysis is applied to the ionopause at Comet Halley and Comet Giacobini-Zinner, showing that the theoretical prediction concerning the stability of this interface based on an earlier linear analysis remains valid in both cases despite the nonlinear stabilization effects.

Ershkovich, A. I.↗
NASA NTRS1985

Convective influence on the stability of a cylindrical solid-liquid interface

Experiments in which a long vertical, heated wire is surrounded by concentric annuli of a melt and its crystalline solid show that the convection state changes from a stable unicell surrounded by a stationary cylindrical solid-liquid interface, to a complex time-dependent flow surrounded by a rotating, helical solid-liquid interface. This transition occurs at a Grashof number of approximately 150, which is an order of magnitude less than the critical Grashof number calculated for a liquid annulus surrounded by rigid walls. A linear stability analysis has been carried out for an infinitely tall vertical annulus. When the deformable nature of the crystal-melt interface is taken into account in the boundary conditions, two new modes of instability arise. The most dangerous mode is asymmetrical and corresponds to helical waves travelling vertically upwards. The critical Grashof number and the scaling properties of the eigenstate agree with experiments. The results clearly demonstrate the coupling of convection with crystal-melt interfacial instabilities.

Fang, Q. T.↗
DOE OSTI2025

Next-generation perovskite photovoltaics: improving, stabilizing, and lead-sealing of record-setting laboratory solar cells towards commercialization

Summary: In the proposed program we plan to improve perovskite photovoltaic performance by developing (1) orientational control of 3D/2D perovskite heterostructures to simplify device architectures, thus improving device efficiencies and stability; (2) high-throughput optical measurements and real-time device simulations for device optimization; (3) robust, dual-pronged lead-sealing and oxygen/moisture/UV barrier films for long-term stability. Specifically, we seek to develop an in-depth understanding of the perovskite film formation, interface passivation, device stability, and environmentally friendly encapsulation, which together will lead to perovskite devices with PCE of over 28%, stability of T80 at 85/85 (85% humidity at 85 degrees C) for 10,000, expected to be equivalent to T90 of 100 hours), and architectures that would satisfy the U.S. EPA and RoHS limits of lead-leaching. The knowledge generated with this project will be applicable to tandem devices with wider-bandgap perovskites.

14 SOLAR ENERGY↗
NASA NTRS1985

Morphological Stability and Fluid Dynamics of Vapor Crystal Growth

A fundamental understanding of the conditions under which crystals can retain morphological stability, i.e., shape stability of the advancing interface, during growth from vapors was studied. Morphological stability (MS) is a necessary condition for the growth of homogeneous single crystals required for numerous device applications. For crystallization from melts, the MS concepts are well developed and are essentially based on heat and mass transfer conditions about the advancing interface. For crystallization from vapors, the MS requirements are more complex and not well understood. The added complexity arises from the fact that anisotropies in interfacial kinetics are typically stronger in crystallization from vapors than from melts. These pronounced anisotropies root in the distinctly lower atomic roughness of most vapor-solid interfaces.

Rosenberger, F.↗
DOE OSTI2025

Charge Regulation Stabilizes the Formation of Ionic Liquid‐Based Amphiphilic Oligomer Droplet Interface Bilayers

Amphiphilic charged oligomers (oligodimethylsiloxane – methylimidazolium cation, ODMS-MIM (+) ), assemble into bilayers using the droplet interface bilayer (DIB) platform, possess similar size and functionality as phospholipid bilayers, but exhibit increased stability. The oligomer ionic headgroups (MIM (+) ) are covalently bound to monodisperse, short-chain (n = 13) hydrophobic tails (ODMS). These self-assemble as monolayer brushes at the oil–aqueous interface of water droplets that are influenced by both the charged cationic headgroups, and the nature of the covalently attached tails in the organic phase. Charge regulation (CR) stabilizes the formation of ordered, molecularly close-packed brush phases, which results in highly insulating, stable DIB membranes, with contributions from specific ion-pairing effects, Debye screening, and voltage-dependent electrocompressive stresses. In the oil phase, interactions between hexadecane, a good solvent for ODMS, and the hydrophobic tails result in extended waiting times for bilayer formation compared to phospholipid DIBs, for which hexadecane is a poor solvent. Close agreement between experimental values and predictions for two key parameters, the critical membrane thickness, h c , and maximal grafted headgroup density, Γ 0 , validate an electrostatic CR model consisting of adsorption and partial neutralization of counterions at a charged interface.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Advancing $otsdaq$ for Optimized Data Acquisition

High-energy physics (HEP) experiments demand data acquisition (DAQ) systems capable of orchestrating complex detector operations, high data throughput, and responsive, real-time feedback. Traditional systems often have steep learning curves, making onboarding difficult for new users. The Off-The-Shelf Data Acquisition $otsdaq$ framework was developed to address these issues by providing a modular and flexible interface that is easier to operate while remaining customizable enough for experimental setups. As the upcoming Mu2e experiment prepares for deployment, improving stability, usability, and performance has become increasingly critical. Our work enhances $otsdaq$ with features that streamline visualization, correct data metrics, improve debugging workflows, and stabilize the user interface.

Mohammed, Ali (ORCID:0009000860386626)↗
DOE OSTI2024

Pore-Filling Induced Solid Electrolyte Failure of Ti-Doped Na 3 Zr 2 Si 2 PO 12 Characterized by Operando Synchrotron X-Ray Tomography

Solid-state batteries (SSBs), particularly those utilizing sodium metal, are emerging as a promising technology due to their potential for enhanced safety, higher energy density, and longer cycle life. NASICON (Na superionic conductor) materials, known for their robust crystalline structure and high ionic conductivity, are pivotal in the development of efficient sodium all-solid-state batteries. These materials exhibit high room-temperature ionic conductivity and electrochemical stability, making them ideal for various applications. Research has focused on improving NASICON's ionic conductivity and stability through doping, interface regulation, and composite anode design. Recent advancements include Ti-doped Na 3 Zr 2 Si 2 PO 12 (Ti-NZSP), which demonstrates improved surface stability, higher ionic conductivity, and increased critical current density. However, challenges such as Na dendrite formation and mechanical integrity under operational conditions persist. Advanced imaging techniques like operando synchrotron X-ray tomography have provided insights into failure mechanisms, revealing that pore-filling and dendrite growth are significant issues. Understanding these processes is essential for enhancing the performance and safety of Na-based SSBs. Here, this study underscores the need for continued research to address these challenges and develop reliable, high-performance solid-state electrolytes for future energy storage solutions.

25 ENERGY STORAGE↗
DOE OSTI2024

Steam‐Assisted Selective CO 2 Hydrogenation to Ethanol over Ru−In Catalysts

Abstract Multicomponent catalysts can be designed to synergistically combine reaction intermediates at interfacial active sites, but restructuring makes systematic control and understanding of such dynamics challenging. We here unveil how reducibility and mobility of indium oxide species in Ru‐based catalysts crucially control the direct, selective conversion of CO 2 to ethanol. When uncontrolled, reduced indium oxide species occupy the Ru surface, leading to deactivation. With the addition of steam as a mild oxidant and using porous polymer layers to control In mobility, Ru−In 2 O 3 interface sites are stabilized, and ethanol can be produced with superior overall selectivity (70 %, rest CO). Our work highlights how engineering of bifunctional active ensembles enables cooperativity and synergy at tailored interfaces, which unlocks unprecedented performance in heterogeneous catalysts.

Zhou, Chengshuang↗
DOE OSTI2024

Steam-Assisted Selective CO 2 Hydrogenation to Ethanol over Ru–In Catalysts

Multicomponent catalysts can be designed to synergistically combine reaction intermediates at interfacial active sites, but restructuring makes systematic control and understanding of such dynamics challenging. In this work, we unveil how reducibility and mobility of indium oxide species in Ru-based catalysts crucially control the direct, selective conversion of CO 2 to ethanol. When uncontrolled, reduced indium oxide species occupy the Ru surface, leading to deactivation. With the addition of steam as a mild oxidant and using porous polymer layers to control In mobility, Ru–In 2 O 3 interface sites are stabilized, and ethanol can be produced with superior overall selectivity (70 %, rest CO). Our work highlights how engineering of bifunctional active ensembles enables cooperativity and synergy at tailored interfaces, which unlocks unprecedented performance in heterogeneous catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1989

Ballistic electron emission microscopy and spectroscopy of Au/GaAs interfaces

This paper presents the first Schottky barrier results for the Au/GaAs(100) interface prepared completely in situ on GaAs grown by molecular-beam epitaxy. The resulting interface displays unexpected properties which can be interpreted in terms of enhanced electrode interdiffusion. In addition, the capability of molecular-beam epitaxy for in situ processing enables the stabilization of this interface against diffusion and allows the formation of a Au/GaAs system with nearly ideal properties. Newly developed ballistic electron spectroscopy and imaging techniques demonstrate that the heterogeneity present at the interface of Au/GaAs(100) fabricated on chemically treated GaAs substrates is removed.

Kaiser, W. J.↗
DOE OSTI2024

Comparative Analysis of Reactivity of Al and Ga Doped Garnet Solid State Electrolyte at the Interface with Li Metal

Lithium garnet (Li 7 La 3 Zr 2 O 12 , LLZO) based solid electrolytes are leading candidate materials for all-solid-state batteries with lithium metal anodes because of their high ionic conductivity, high mechanical toughness, and superior electrochemical stability. While doping LLZO with Al and Ga increases its ionic conductivity by stabilizing the cubic phase, the impact of dopants on its (electro)chemical stability at the interfaces with Li metal is critical. Here, our study of differences between Al- and Ga-doped LLZO when interfaced with lithium metal using X-ray photoelectron spectroscopy and density functional theory shows a higher propensity of Ga to move across LLZO interface with Li metal and form Ga-Li alloy. Additionally, neutron diffraction reveals loss of cubic phase resulting from the loss of dopant that explains electrochemical behavior differences between Ga- and Al-doped LLZO. Overall, our study reveals the key role of dopant chemistry in enabling stable solid electrolyte materials for all-solid-state batteries.

Klenk, Matthew↗
NASA NTRS1982

Single-mode theory of diffusive layers in thermohaline convection

A two-layer configuration of thermohaline convection is studied, with the principal aim of explaining the observed independence of the buoyancy-flux ratio on the stability parameter when the latter is large. Temperature is destabilizing and salinity is stabilizing, so diffusive interfaces separate the convecting layers. The convection is treated in the single-mode approximation, with a prescribed horizontal planform and wavenumber. Surveys of numerical solutions are presented for a selection of Rayleigh numbers R, stability parameters lambda and horizontal wavenumbers. The solutions yield a buoyancy flux ratio chi that is insensitive to lambda, in accord with laboratory experiments. However chi increases with increasing R, in contradiction to laboratory observations.

Gough, D. O.↗