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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 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Liquid-Phase Modeling in Heterogeneous Catalysis

The notion that solvents can affect the chemical reactivity has been prevalent in the homogeneous catalysis community, going back as far as 1863.(1) Remarkable changes in reaction rate have been reported in the seminal work of Menschutkin, who demonstrated a change in reaction rate constant up to a factor of 700 as a function of the solvents employed for the reaction of triethylamine with ethyl iodide at 373 K.(2) It is well-known nowadays that solvents can affect the reaction rate, reaction mechanism, and selectivity of chemical reactions occurring in condensed phase. While solvent effects usually lead to changes in reaction rates of up to 3 orders of magnitude, rate increases of 9 orders of magnitude have been reported.(3, 4) In homogeneous metal catalysis such as hydroformylation, hydrogenation, and cross-coupling reactions, solvent effects have been studied systematically and exploited for industrial applications.(5) Substantial solvent effects have also been reported in heterogeneous catalysis for several hydrogenation,(6-9) oxidation,(10-12) and electrochemical reactions (where electric field effects lead in addition to an electric double layer(13-16)). However, in heterogeneous catalysis, systematic studies of solvation effects are rare, and solvent effects are generally not well understood. In this context, we note that liquid-phase processing is highly desirable for process cost reduction and high product selectivity for the heterogeneously catalyzed conversion of highly functionalized lignocellulosic biomass, because the feedstocks contain significant amounts of water, are produced in aqueous-phase environments, and reactant molecules are highly water-soluble, reactive, and thermally unstable.(17-19) Processing at relatively low temperatures in condensed phase has therefore the potential to (1) minimize undesirable thermal degradation reactions, (2) increase the targeted product selectivity, and (3) facilitate the product separation from excess water because reaction products often contain less oxygen and are therefore less hydrophilic than the feed streams.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

SISGR: Physical chemistry of reaction dynamics in ionic liquids

This document is the final technical report for the five-institution project titled, “SISGR: Physical chemistry of reaction dynamics in ionic liquids”. The project included the groups of Edward Castner, Jr. at Rutgers, Mark Maroncelli at Penn State, Claudio Margulis at Univ. of Iowa, David Blank at Univ. of Minnesota, and James Wishart at Brookhaven National Laboratory. The project spanned several funding periods between 2009 and 2017, with a no-cost extension at Rutgers continuing until 3/14/2018. The scientific research carried out included an array of experimental and theoretical investigations into the properties and chemical reactivity of room-temperature ionic liquids (ILs). Such ILs are of broad importance for energy science and technology applications, including their use in advanced batteries, supercapacitors and fuel cells; processing of biomass to liquid fuels; and for solubilizing and separating high-level radionuclides from nuclear waste products. Specific examples include the study of the transport and structural properties of the liquids, studies of photo-induced electron-transfer reactions, and characterization of solvated electrons in the ILs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Identification of efficient and stable solid-solid electrochemical interfaces for Li-S batteries. Final Report

The objective of this work is to develop a better understanding of the interactions between battery components that drive the observed battery performance. Using computational tools at the atomistic level, we elucidate molecular, crystal, and amorphous structures, interfacial structures and reactions, and electrochemical behavior. We focus on Li metal anodes, liquid electrolytes, solid electrolytes, S cathodes, and metal-oxide cathodes, and their corresponding interfaces. Within liquid electrolytes, we study their bulk structure and dynamics, as a function of salt concentration. The analysis allows to understand the formation of localized high concentrated regions as the solvent is substituted by a weakly interacting diluent species. Analysis of the electron distribution yields the reactive behavior at interfaces. Moreover, we employ tools that allow the characterization of ion and electron transport at interfaces, during the processes of solvation and desolvation occurring while cycling. For Sulfur cathodes we elucidate synthesis processes and the role of carbon-sulfur and nitrogen-sulfur interactions not only to provide electronic conductivity but also to define alternative reaction pathways during discharge of Li-S batteries. Full-cell simulations offer new insights regarding the integration of all the battery components. Our studies also include solid electrolytes and their interfaces with Li metal, S-C, and metal-oxide electrodes.

25 ENERGY STORAGE↗
DOE OSTI2024

Enhancing Cycling Stability of Lithium Metal Batteries by a Bifunctional Fluorinated Ether

Abstract The lifespan of lithium (Li) metal batteries (LMBs) can be greatly improved by the formation of inorganic‐rich electrode‐electrolyte interphases (EEIs) (including solid‐electrolyte interphase on anode and cathode‐electrolyte interphase on cathode). In this work, a localized high‐concentration electrolyte containing lithium bis(fluorosulfonyl)imide (LiFSI) salt, 1,2‐dimethoxyethane (DME) solvent and 1,2‐bis(1,1,2,2‐tetrafluoroethoxy)ethane (BTFEE) diluent is optimized. BTFEE is a fluorinated ether with weakly‐solvating ability for LiFSI so it also acts as a co‐solvent in this electrolyte. It can facilitate anion decomposition at electrode surfaces and promote the formation of more inorganic‐rich EEI layers. With an optimized molar ratio of LiFSI:DME:BTFEE = 1:1.15:3, LMBs with a high loading (4 mAh cm −2 ) lithium nickel manganese cobalt oxide (LiNi 0.8 Mn 0.1 Co 0.1 ) cathode can retain 80% capacity in 470 cycles when cycled in a voltage range of 2.8–4.4 V. The fundamental understanding on the functionality of BTFEE revealed in this work provides new perspectives on the design of practical high‐energy density battery systems.

25 ENERGY STORAGE↗
DOE OSTI2022

Chemical Tuning Meets 2D Molecular Magnets

Two-dimensional (2D) magnets provoke a surge of interest in large anisotropy in reduced dimensions and are promising for next-generation information technology where dynamic magnetic tuning is essential. Until recently, the crucial metal-organic magnet Cr(pyz) 2 ∙xLiCl∙yTHF with considerable high coercivity and high-temperature magnetic order opens up a new platform to control magnetism in metal-organic materials at room temperature. Here we report an in-situ chemical tuning route to realize the controllable transformation of low-temperature magnetic order into room-temperature hard magnetism in Cr(pyz) 2 ∙xLiCl∙yTHF. The chemical tuning via electrochemical lithiation and solvation/desolvation exhibits continuously variable magnetic features from cryogenic magnetism to the room-temperature optimum performance of coercivity (H c ) of 8500 Oe and energy product of 0.6 MGOe. Such chemically flexible tunability of room-temperature magnetism is ascribed to the different degrees of lithiation and solvation that modify the stoichiometry and Cr-pyrazine coordination framework. Furthermore, the additively manufactured hybrid magnets show air stability and electromagnetic induction, providing potential applications. Our findings here suggest chemical tuning as a universal approach to control the anisotropy and magnetism of 2D hybrid magnets at room temperature, promising for data storage, magnetic refrigeration, and spintronics.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Development of Electrolytes under Lean Condition in Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries stand out as one of the promising candidates for next-generation electrochemical energy storage technologies. A key requirement to realize high-specific-energy Li–S batteries is to implement low amount of electrolyte, often characterized by the electrolyte/sulfur (E/S) ratio. Low E/S ratio aggravates the known challenges for Li–S batteries and introduces new ones originated from the high concentration of polysulfides in limited electrolyte reservoir. Here, in this review, the connections between the fundamental properties of electrolytes and the electrochemical/chemical reactions in Li–S batteries under lean electrolyte condition are elucidated. The emphasis is on how the solvating properties of the electrolyte affect the fate of polysulfides. Built upon the mechanistic analysis, different strategies to design lean electrolytes to improve the overall process of Li–S reactions and Li anode protection are discussed.

25 ENERGY STORAGE↗
DOE OSTI2026

Electrolyte Design for Fast‐Charging Lithium‐Based Batteries

Fast charging is essential for the widespread adoption of lithium (Li)-ion batteries, but it is fundamentally limited by sluggish interfacial kinetics, Li plating, and electrolyte instability at high current densities. Over the past decade, electrolyte engineering has emerged as a key strategy to address these challenges. This review summarizes the development of fast-charging electrolytes over the past ten years and outlines a design framework. Electrolyte formulations are first deconstructed into their main components—solvents, salts, and functional additives—and representative strategies for tuning solvation structure and interphase chemistry are discussed to suppress Li plating and improve interfacial kinetics. The discussion then extends to advanced electrolyte systems, particularly localized high-concentration electrolytes (LHCEs), and their compatibility with different anode chemistries. Advanced characterization techniques are also summarized and categorized based on destructiveness, spatial and temporal resolution, quantitative analysis, and the chemical species or processes probed across multiple length scales. Recent progress in AI-enabled electrolyte discovery and battery management system (BMS) strategies for optimized fast-charging protocols is further highlighted. Finally, perspectives are presented on translating electrolyte innovations from academic research to practical applications, with emphasis on cell format, realistic operating conditions, and manufacturability.

25 ENERGY STORAGE↗
DOE OSTI2026

Tuning the Mechanical Properties of Crosslinked Copolymers via Sequence and Solvent‐Selective Swelling for Vat Photopolymerization

Block copolymers (BCPs) offer distinct advantages for vat photopolymerization by enabling mechanically programmable network structures through microphase-separated morphologies that can be kinetically trapped during curing, yielding properties unattainable in homogeneous resins. However, the respective roles of repeat-unit sequence and solvent environment, together with their interplay in directing network formation and mechanical performance, remain unclear. Here, we synthesize a series of CO 2 -based polycarbonate copolymers comprising a crosslinkable glassy poly(vinyl cyclohexene carbonate) (PVCHC, A block) and a non-crosslinkable soft poly(propylene carbonate) (PPC, B block). The polymer sequence is systematically varied (ABA, BAB, and statistical), and solvent choice controls block-selective swelling to jointly control gelation behavior, microphase morphology, and mechanical response through changes in the accessibility and local environment of photocrosslinkable vinyl groups during network formation, as revealed by photorheology and small angle x-ray scattering. By tuning polymer sequence and curing solvent, we transform nominally identical formulations from brittle to highly ductile materials, achieving a three-orders-of-magnitude range in toughness (0.003 to 9.1 MJ m −3 ). These results establish clear structure–processing–property relationships and identify polymer sequence and selective solvation as powerful strategies for programming both printability and performance of block copolymer resins for additive manufacturing.

additive manufacturing↗
DOE OSTI2011

Chitosan Molecular Structure as a Function of N-Acetylation

Molecular dynamics simulations have been carried out to characterize the structure and solubility of chitosan nanoparticle-like structures as a function of the deacetylation level (0, 40, 60, and 100%) and the spatial distribution of the N-acetyl groups in the particles. The polysaccharide chains of highly N-deacetylated particles where the N-acetyl groups are uniformly distributed present a high flexibility and preference for the relaxed two-fold helix and five-fold helix motifs. When these groups are confined to a given region of the particle, the chains adopt preferentially a two-fold helix with f and w values close to crystalline chitin. Nanoparticles with up to 40% acetylation are moderately soluble, forming stable aggregates when the N-acetyl groups are unevenly distributed. Systems with 60% or higher N-acetylation levels are insoluble and present similar degrees of swelling regardless the distribution of their N-acetyl groups. Overall particle solvation is highly affected by electrostatic forces resulting from the degree of acetylation. The water mobility and orientation around the polysaccharide chains affects the stability of the intramolecular O3- HO3(n) ... O5(n+ 1) hydrogen bond, which in turn controls particle aggregation.

08 HYDROGEN↗
DOE OSTI2017

Engineering Redox Potential of Lithium Clusters for Electrode Material in Lithium-Ion Batteries

Low negative electrode potential and high reactivity makes lithium (Li) ideal candidate for obtaining highest possible energy density among other materials. Here, we show a novel route with which the overall electrode potential could significantly be enhanced through selection of cluster size. In using first principles density functional theory and continuum dielectric model, we studied free energy and redox potential as well as investigated relative stability of Li n (n ≤ 8) clusters in both gas phase and solution. We found that Li 3 has the lowest negative redox potential (thereby highest overall electrode potential) suggesting that cluster based approach could provide a novel way of engineering the next generation battery technology. The microscopic origin of Li 3 cluster’s superior performance is related to two major factors: gas phase ionization and difference between solvation free energy for neutral and positive ion. Taken together, our study provides insight into the engineering of redox potential in battery and could stimulate further work in this direction.

25 ENERGY STORAGE↗
DOE OSTI2017

Quantum chemical modeling of superbase-catalyzed reactions of acetophenone and methyl mesityl ketone with acetylene

The mechanisms of furan formation and the competitive reaction of 1,5-diketone formation from 1-mesitylbut-2-en-1-one (1a) and 1-phenylbut-2-en-1-one (1b) were studied using the B3LYP/6-311++G**//B3LYP/6-31+G* quantum chemical approach taking into account solvation effects in terms of the IEFPCM model. The addition to 1a of the ethynide ion to form β-acetylene enolate ion (2a) occurs with the activation energy ΔG{sup ≠} = 13.3 kcal mol{sup –1}, while the further intramolecular O-vinylation with the closure of 2a to the dihydrofuran cycle of the dihydrofuran carbanion is the rate-determining step in the reaction pathway of substituted furan formation needing the activation energy G{sup ≠} = 19.5 kcal mol{sup –1}. The alternative addition of the mesitylethenolate ion to 1a to form the 1,5-diketone carbanion is associated with a higher (by 3.4 kcal mol{sup –1}) free activation energy than that of ethynide ion addition. In contrast, in the case of 1b, the addition at the C=C bond of the phenylethenolate ion rather than of the ethynide ion to form the 1,5-diketone carbanion is more preferable, since its activation free energy is 1.5 kcal mol{sup –1} lower. The quantum chemical calculation results are consistent with the experimental data.

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

DFT studies of the electron density distribution and donor-acceptor interactions in water-soluble aminohydroximate metallamacrocyclic Ca{sup II} and Y{sup III} complexes

The topology of the electron density and the nature of donor-acceptor interactions in copper-based glycinehydroximate metallamacrocycles bearing calcium(II) and yttrium(III) have been studied for the first time in terms of the density functional theory (DFT). The DFT calculations at the M06/Def2-TZVP level were performed taking into account non-specific (PCM) and specific solvation. Quantitative estimations of the donor-acceptor interactions and topological properties of the electron density were obtained. According to them, the thermodynamic stability of the yttrium complex is higher than that of the calcium analog. The calculated values of the Gibbs energy changes indicate the spontaneous substitution of Ca{sup 2+} by Y{sup 3+} in the metallamacrocycle in an aqueous medium.

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

Nature of Electronically Excited States of Furocoumarins

A comprehensive study of spectral-luminescent and photophysical properties of coumarin sensitizers is performed using the methods of quantum chemistry, electron spectroscopy, and fluorescence. A comparative study of photophysical processes occurring in 8-methoxypsoralen (8-MOP) and 4,9-dimethoxy-7-methylfuro [3,2-g][1] benzofuran-5-1 (khellin) is performed using the quantum-chemical software package based on the semi-empirical method of intermediate neglect of differential overlap with original spectroscopic parameterization. The dependences of the fluorescent properties and reactivity of the compounds on the geometry and composition of the solvation shell of molecules are established. It is shown that incorporation of additional methoxy groups in the structure of molecules has the strongest effect on the spectral-luminescent characteristics of khellin compared with 8-MOP.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Continuum Electrostatics Approaches to Calculating pKas and Ems in Proteins

Proteins change their charge state through protonation and redox reactions as well as through binding charged ligands. The free energy of these reactions are dominated by solvation and electrostatic energies and modulated by protein conformational relaxation in response to the ionization state changes. Although computational methods for calculating these interactions can provide very powerful tools for predicting protein charge states, they include several critical approximations of which users should be aware. This chapter discusses the strengths, weaknesses, and approximations of popular computational methods for predicting charge states and understanding their underlying electrostatic interactions. The goal of this chapter is to inform users about applications and potential caveats of these methods as well as outline directions for future theoretical and computational research.

biomolecules↗
DOE OSTI2026

Actinium–DOTA coordination in water from hybrid ML/MM: Structure, free energies, and water-exchange pathways

Quantitative simulation of trivalent ƒ-block chelates in water remains challenging because bonded and non-bonded force-field models make different approximations for coordination structure, exchange dynamics, and ion–ligand interactions in highly charged systems. Here, we develop a hybrid machine-learning/molecular-mechanics (ML/MM) framework for Ac 3+ –DOTA in explicit solvent by training an E(3)-equivariant neural network potential (MACELES) on mechanically embedded QM/MM data for Ac aquo and Ac–DOTA species and coupling it to NAMD 2.14 with particle-mesh Ewald electrostatics. Nanosecond ML/MM trajectories remain numerically stable and preserve chelate integrity, yielding a compact DOTA inner shell with an inner-sphere water coordination number of CN Ac,O w ≈ 1.7 arising from a dynamic equilibrium between one- and two-water states (37.5% and 59.9% of frames; three waters 2.5%). A 5 ns potential of mean force shows two low-lying basins at CN Ac,O w ≈ 1 and CN Ac,O w ≈ 2. DFT end-state free energies are consistent with the ML/MM profile, and DFT minimum-energy paths provide a qualitative electronic-structure reference for the observed basin connectivity. State-resolved kinetics reveal picosecond water-exchange pathways that couple hydration changes to transient DOTA arm fluctuations, and training-set comparisons show that temperature-matched Ac–DOTA data optimize energy/force accuracy while more diverse solvated data improve charge prediction. Overall, the present hybrid ML/MM model provides a practical description of Ac 3+ –DOTA hydration thermodynamics and short-time exchange behavior in explicit water at MD-like cost.

Actinium↗
DOE OSTI2017

Crystal structure and thermodynamic dissection of chitin oligosaccharide binding to the LysM module of chitinase-A from Pteris ryukyuensis

Highlights: • Crystal structure of a LysM module from Pteris ryukyuensis chitinase-A (PrLysM2) was determined at a resolution of 1.8 Å. • LysM module recognizes chitin oligosaccharides in a shallow groove on the molecule. • Thermodynamic dissection of the binding energetics of (GlcNAc){sub 6} to PrLysM2 was carried out. • The binding site comprises of five sugar-binding subsites. We determined the crystal structure of a LysM module from Pteris ryukyuensis chitinase-A (PrLysM2) at a resolution of 1.8 Å. Structural and binding analysis of PrLysM2 indicated that this module recognizes chitin oligosaccharides in a shallow groove comprised of five sugar-binding subsites on one side of the molecule. The free energy changes (ΔG{sub r}°) for binding of (GlcNAc){sub 6}, (GlcNAc){sub 5}, and (GlcNAc){sub 4} to PrLysM2 were determined to be −5.4, −5,4 and −4.6 kcal mol{sup −1}, respectively, by ITC. Thermodynamic dissection of the binding energetics of (GlcNAc){sub 6} revealed that the driving force is the enthalpy change (ΔH{sub r}° = −11.7 ± 0.2 kcal/mol) and the solvation entropy change (−TΔS{sub solv}° = −5.9 ± 0.6 kcal/mol). This is the first description of thermodynamic signatures of a chitin oligosaccharide binding to a LysM module.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Ion-specific effects influencing the dissolution of tricalcium silicate

It has been recently demonstrated that the dissolution kinetics of tricalcium silicate (C{sub 3}S) is driven by the deviation from its solubility equilibrium. In this article, special attention is paid to ions relevant in cement chemistry likely to interact with C{sub 3}S. In order to determine whether specific effects occur at the interface C{sub 3}S–water, particular efforts have been made to model ion activities using Pitzer's model. It has been found that monovalent cations and monovalent anions interact very little with the surface of C{sub 3}S. On the other side, divalent anions like sulfate slow down the dissolution more strongly by modifying the surface charging of C{sub 3}S. Third, aluminate ions covalently bind to surface silicate monomers and inhibit the dissolution in mildly alkaline conditions. The formation and the breaking of these bonds depend on pH and on [Ca{sup 2+}]. Thermodynamic calculations performed using DFT combined with the COSMO-RS solvation method support the experimental findings.

36 MATERIALS SCIENCE↗