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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 1,243 records · Page 69
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Electronic Energies Are Not Enough: An Ion Mobility-Aided, Quantum Chemical Benchmark Analysis of H + GPGG Conformers

Peptides and proteins exist not as single, lowest energy structures but as ensembles of states separated by small barriers. In order to study these species we must be able to correctly identify their gas phase conformational distributions, and ion mobility spectrometry (IMS) has arisen as an experimental method for assessing the gas phase energetics of flexible peptides. Here, we present a thorough exploration and benchmarking of the low energy conformers of the small, hairpin peptide H+ GPGG with the aid of ion mobility spectrometry against a wide swath of density functionals (35 dispersion-corrected and uncorrected functionals represented by 21 unique exchange–correlation functionals) and wave function theory methods (15 total levels of theory). The three experimentally resolved IMS peaks were found to correspond to three distinct pairs of conformers, each pair composed of species differing only by the chair or boat configuration of the proline. Two of the H+ GPGG conformer pairs possess a cis configuration about the Pro–Gly1 peptide bond while the other adopts a trans configuration. While the experimental spectrum reports a higher intensity for the cis-1 conformer than the trans conformer, 13 WFT levels of theory, including a complete basis set CCSD(T) extrapolation, obtain trans to be favored in terms of the electronic energy. This same effect is seen in 14 of the 18 dispersion-corrected density functionals studied, whereas the remaining 17 functionals show more variety. Only when Gibbs free energies are considered do the WFT methods and dispersion-corrected functionals reflect the experimental distribution. CAM-B3LYP-D3BJ emerges as the best-performing density functional, matching the experimental distribution and the CCSD(T)/CBS relative energies within 6%. Further analysis reveals the trans conformer to be favored electronically, but entropically disfavored, leading to the experimental preference of the cis-1 conformer. Furthermore, these results highlight the danger in considering only the electronic energies, which is common practice in electronic structure theory predictions of conformational energy distributions. Additionally, the effects of temperature and scaling of the frequencies used in obtaining the Gibbs free energies are explored.

Energy↗
DOE OSTI2017

Mesoscale Elucidation of Solid Electrolyte Interphase Layer Formation in Li-Ion Battery Anode

Capacity fade in lithium-ion batteries largely originates from the undesired electrolyte decomposition, which results in the formation of solid electrolyte interphase (SEI) and the anode surface passivation. In this work, a mesoscale interfacial modeling approach is developed to investigate the formation and growth of the SEI film on a typical graphite based anode over several cycles. It is found that lithium diffusion kinetics in the SEI film significantly affects the SEI growth rate. A lower lithium diffusion barrier leads to a higher growth rate. The present model demonstrates that the SEI thickness is a linear function of the square root of the charging time over long-time cycling. Growth of multicomponent SEI film is also elucidated. It is found that the heterogeneity of the SEI film may lead to instability in lithium ion concentration distribution.

25 ENERGY STORAGE↗
DOE OSTI2023

The Relationship between Ionic Conductivity and Solvation Structures of Localized High-Concentration Fluorinated Electrolytes for Lithium-Ion Batteries

Localized high concentration electrolyte (LHCE) combines a diluent with high concentration electrolyte (HCE), offering promising properties. The ions, solvent, and diluent interact to form a complex heterogenous liquid structure, where high salt concentration clusters are embedded in diluent. Optimizing LHCE for desired electrolyte properties like high ionic conductivity, low viscosity, effective solid electrolyte interphase (SEI) formability, within the vast chemical and compositional design space requires deeper understanding and theoretical guidance. For this work, we investigated the structures and conductivity of LHCEs based on a fluorinated solvent with two different diluents at varying concentrations. The 2,2,3,3-tetrafluoropropyl trifluoroacetate (TFPTFA) enters the solvation cluster due to its stronger Li-ion interactions, whereas 1,1,2,2-tetrafuoroethyl 2,2,2-trifuoroethyl ether (TFETFE) enters only at extremely high diluent concentrations. The ionic conductivity increases with decreasing diluent concentrations, with a slope change during cluster percolation. Overall, TFETFE demonstrates higher effectiveness than TFPTFA, forming higher local salt concentration clusters, and resulting in higher ionic conductivity.

cluster chemistry↗
DOE OSTI2018

Internally Referenced DOSY-NMR: A Novel Analytical Method in Revealing the Solution Structure of Lithium-Ion Battery Electrolytes

Here, a novel methodology is reported on the use of internally referenced diffusion-ordered spectroscopy (IR-DOSY) in divulging the solution structure of lithium-ion battery electrolytes. Toluene was utilized as the internal reference for 1 H-DOSY analysis due to its exceptionally low donor number and reasonable solubility in various electrolytes. With the introduction of the internal reference, the solvent coordination ratio of different species in the electrolytes can be easily determined by 1 H-DOSY or 7 Li-DOSY. This new technique was applied to different carbonate electrolytes, and the results were consistent with a Fourier transform infrared (FTIR) analysis. Compared to conventional vibrational spectroscopy, this IR-DOSY technique avoids the complicated deconvolution of the spectrum and allows determination of the solvent coordination ratio of different species in electrolyte systems with two or more organic solvents.

25 ENERGY STORAGE↗
DOE OSTI2021

Enhanced Ion Conductivity through Hydrated, Polyelectrolyte-Grafted Cellulose Nanocrystal Films

Here,iIonically conductive, hydrated polyelectrolyte nanocomposites are prepared from iodomethane-treated poly(2-vinylpyridine) (mPV)-grafted cellulose nanocrystals (MxG-CNC-g-mPV). These polyelectrolyte-grafted nanoparticle (PEGN) films exhibit an order-of-magnitude higher iodide ion conductivity relative to mPV films and a high in-plane/through-plane anisotropy. The PEGN architecture prevents CNC aggregation, maximizing the CNC/polyelectrolyte interface. PEGN films were prepared with varying polymer graft density (0.03-0.12 chains/nm 2 ) and molecular weight (7k-30k g/mol). The greatest ion conductivity enhancement is observed with lower molecular weight, higher density grafts: ca. 89 ± 6 mS/cm (140 ±10 mS/cm accounting for the volume of the CNC) versus 3.3 ± 0.4 mS/cm for ungrafted mPV. Poly(styrene-block-2-vinylpyridine)-grafted CNCs were prepared in which the insulating polystyrene block or the conducting mPV block was directly attached to the CNCs; only the films with the mPV block closest to the CNCs exhibited an enhancement in conductivity relative to mPV. Together, these data point to beneficial CNC/polyelectrolyte interfacial effects, resulting in significant ionic conductivity enhancement along the length of the CNCs in these films.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2025

The Influence of Charge Correlation and Ion Solvation on the Phase Behavior of Single-Ion Conducting Polymer Blend Electrolytes Using SAXS/SANS

Single-ion conducting polymer blends (SICPBs) have demonstrated exceptional electrochemical performance as solid-state battery electrolytes; however, their nanoscale morphology and thermodynamic behavior remain unexplored. In this work, we investigate blends composed of deuterated poly(ethylene oxide) and poly[lithium sulfonyl(trifluoromethane sulfonyl)imide methacrylate], dPEO/P(LiMTFSI), and report the first experimental study of the nanostructures of charge-neutral polymer blends using small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). Despite the macroscopic miscibility indicated by a single glass-transition temperature, SANS and SAXS results reveal disordered, charge-correlated nanostructures that are strongly influenced by blend composition and temperature. At low concentrations of charge polymer, the scattering is dominated by concentration fluctuations, and the random phase approximation is applied to extract values of the Flory–Huggins interaction parameter, χ SC . At higher charged polymer content, concentration fluctuations are suppressed, and a correlation model is used to characterize the nanostructures of the charge correlations. We find that the structures of the charge correlations are highly dependent on blend composition─consistent with predictions from Sing’s self-consistent field theory-liquid state models. Understanding these features is essential for uncovering the ion transport mechanism that leads to improved electrochemical performance previously reported in SICPB systems.

25 ENERGY STORAGE↗
DOE OSTI2019

Tailoring the Surface of Silicon Nanoparticles for Enhanced Chemical and Electrochemical Stability for Li-Ion Batteries

Organic monolayers of epoxy-containing oligo(ethylene oxide)s were grafted to the surface of silicon nanoparticles via a hydrosilylation reaction. The surface functional groups suppressed the chemical and electrochemical reactivity of the as-grown and lithiated silicon nanoparticles with high material utilization. A robust Si/electrolyte interphase was formed with the participation of the grafted organic groups with facilitated Li+ transfer and was further enforced by electrode integrity via the epoxy/poly(acrylic acid) (PAA) binder reaction. The improved cycling stability and post-test analysis indicate that surface functionalization on the Si particle level is a feasible approach to enabling a Si anode in high-energy-density lithium-ion batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Rechargeable Zinc-Aqueous Polysulfide Battery with a Mediator-Ion Solid Electrolyte

Large scale energy storage for the electric grid will need low cost and high energy density solutions. We demonstrate in this letter a rechargeable zinc-aqueous polysulfide battery in which a metallic zinc anode is separated from a liquid aqueous polysulfide catholyte by an alkali-metal-ion solid-state electrolyte, wherein the alkali metal ion is Na + or Li + . The solid-state electrolyte effectively separates the anode from the reactive polysulfide catholyte, preventing the crossover of the polysulfide species and maintaining good electrochemical performance with a reversible discharge capacity of 822 mA h g -1 with nearly 100% Coulombic efficiency.

25 ENERGY STORAGE↗
DOE OSTI2019

In Situ Focused Ion Beam Scanning Electron Microscope Study of Microstructural Evolution of Single Tin Particle Anode for Li-Ion Batteries

Tin (Sn) is a potential anode material for high-energy density Li-ion batteries because of its high capacity, safety, abundance and low cost. However, Sn suffers from large volume change during cycling, leading to fast degradation of the electrode. For the first time, the microstructural evolution of micrometer-sized single Sn particle was monitored by focused-ion beam (FIB) polishing and scanning electron microscopy (SEM) imaging during electrochemical cycling by in situ FIB-SEM. Our results show the formation and evolution of cracks during lithiation, evolution of porous structure during delithiation and volume expansion/contraction during cycling. The electrochemical performance and the microstructural evolution of the Sn microparticle during cycling are directly correlated, which provides insights for understanding Sn-based electrode materials.

25 ENERGY STORAGE↗
DOE OSTI2021

Stress- and interface-compatible red phosphorus anode for high-energy and durable sodium-ion batteries

Sodium-ion battery is a promising candidate for energy storage application, but the absence of high-capacity and low-cost anode materials significantly limit their practical specific energy and cost. Red phosphorus (RP) possesses a high theoretical specific capacity but suffers from large volume change, low electronic conductivity and unstable solid-electrolyte interphase (SEI). Herein, a hierarchical micro/nanostructured antimony-doped RP/carbon anode was developed, which demonstrate extraordinary electrochemical performance with high initial Coulombic efficiency of ~90%, high areal (~1.7 mAh cm-2) capacity together with good cycle stability and rate capability. Combined experimental and computational studies consistently revealed that such a unique structural design can dramatically accommodate the mechanical stress and moreover effectively restrain the undesired decomposition of electrolyte solvents regardless of electrolytes formulation, resulting in superior structural integrity and thin/robust SEI formation during cycling. The present finding has offered an alternative strategy for stress management and interface engineering on high-capacity alloying-based anode materials.

Liu, Xiang↗
DOE OSTI2015

Observation Of Electron-beam-induced Phase Evolution Mimicking The Effect Of Charge-discharge Cycle In Li-rich Layered Cathode Materials Used For Li-ion Batteries

Capacity loss, and voltage fade upon electrochemical charge-discharge cycling observed in lithium-rich layered cathode oxides (Li[LixMnyTM1-x-y]O2 , TM = Ni, Co or Fe) have recently been identified to be correlated to the gradual phase transformation, featuring the formation of a surface reconstructed layer (SRL) that evolves from a thin (<2 nm), defect spinel layer upon the first charge, to a relatively thick (~5 nm), spinel or rock-salt layer upon continuous charge-discharge cycling. Here we report observations of a SRL and structural evolution of the SRL on the Li[Li0.2Ni0.2Mn0.6]O2 (LMR) particles, which are identical to those reported due to the charge-discharge cycle but are a result of electron-beam irradiation during scanning transmission electron microscopy (STEM) imaging. Sensitivity of the lithium-rich layered oxides to high-energy electrons leads to the formation of thin, defect spinel layer on surfaces of the particles when exposed to a 200 kV electron beam for as little as 30 seconds under normal high-resolution STEM imaging conditions. Further electron irradiation produces a thicker layer of the spinel phase, ultimately producing a rock-salt layer at a higher electron exposure. Atomic-scale chemical mapping by energy dispersive X-ray spectroscopy in STEM indicates the electron-beam-induced SRL formation on LMR is accomplished by migration of the transition metal ions to the Li sites without breaking down the lattice. This study provides an insight for understanding the mechanism of forming the SRL and also possibly a mean to study structural evolution in the Li-rich layered oxides without involving the electrochemistry.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2021

Operando X-ray Diffraction Studies of the Mg-Ion Migration Mechanisms in Spinel Cathodes for Rechargeable Mg-Ion Batteries

A promising high-voltage spinel oxide cathode material MgCrMnO 4 with 18% Mg/Mn inversion was synthesized successfully. A new custom operando battery device was designed to study the cation migration mechanisms of the MgCrMnO 4 cathode using 0.1 M Mg(TPFA) 2 electrolyte dissolved in triglyme and activated carbon as the anode. For the first time in multivalent batteries, high-quality operando diffraction data enabled the accurate quantification of cation contents in the host structure. Besides the exceptional reversibility of 12% Mg 2+ insertion in Mg 1- x CrMnO 4 ( x ≤ 1), a partially reversible insertion of excess Mg 2+ during overdischarging was also observed. Moreover, the insertion/extraction reaction was experimentally shown to be accompanied by a series of cation redistributions in the spinel framework, which were further supported by density functional theory calculations. Furthermore, the inverted Mn is believed to be directly involved in the cation migrations, which would cause voltage hysteresis and irreversible structural evolution after overdischarging. Tuning the Mg/Mn inversion rate could provide a direct path to further optimize spinel oxide cathodes for Mg-ion batteries, and more generally, the operando techniques developed in this work should play a key role in understanding the complex mechanisms involved in multivalent ion insertion systems.

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

Collapse of LiNi 1– x–y Co x Mn y O 2 Lattice at Deep Charge Irrespective of Nickel Content in Lithium-Ion Batteries

Volume variation and the associated mechanical fracture of electrode materials upon Li extraction/insertion are a main cause limiting lifetime performance of lithium-ion batteries. For LiNi 1-x-y Co x Mn y O 2 (NCM) cathodes, abrupt anisotropic collapse of the layered lattice structure at deep charge is generally considered characteristic to high Ni content and can be effectively suppressed by elemental substitution. Herein, we demonstrate the lattice collapse is a universal phenomenon almost entirely dependent on Li utilization, and not Ni content, of NCM cathodes upon delithiation. With Li removal nearing 80 mol%, very similar c-axis lattice shrinkage of around 5% occurs concurrently for NCMs synthesized in-house regardless of nickel content (90, 70, 50, or 33 mol%); meanwhile, the a-axis lattice contracts for high-Ni NCM, but it expands for low-Ni NCM. We further reveal Co-Mn co-substitution in NCM barely, if at all, affects several key structural aspects governing the lattice distortion upon delithiation. Finally, our results highlight the importance of evaluating true implications of compositional tuning on high-Ni layered oxide cathode materials to maximize their charge-storage capacities for next-generation high-energy Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2020

Current status and future directions of multivalent metal-ion batteries

Batteries based on multivalent metals have the potential to meet the future needs of large-scale energy storage, due to the relatively high abundance of elements such as magnesium, calcium, aluminium and zinc in the Earth’s crust. However, the com- plexity of multivalent metal-ion chemistries has led to rampant confusions, technical challenges, and eventually doubts and uncertainties about the future of these technologies. In this Review, we clarify the key strengths as well as common misconceptions of multivalent metal-based batteries. We then examine the growth behaviour of metal anodes, which is crucial for their safety promises but hitherto unestablished. We further discuss scrutiny of anode efficiency and cathode storage mechanism pertaining to complications arising from electrolyte solutions. Lastly, we critically review existing cathode materials and discuss design strategies to enable genuine multivalent metal-ion-based energy storage materials with competitive performance.

25 ENERGY STORAGE↗
DOE OSTI2023

Pattern of global spin alignment of ϕ and K*0 mesons in heavy-ion collisions

The strong force, as one of the four fundamental forces at work in the universe, governs interactions of quarks and gluons, and binds together the atomic nucleus. Notwithstanding decades of progress since Yukawa first developed a description of the force between nucleons in terms of meson exchange 1 , a full understanding of the strong interaction remains a major challenge in modern science. One remaining difficulty arises from the non-perturbative nature of the strong force, which leads to the phenomenon of quark confinement at distance scales on the order of the size of the proton. Here we show that in relativistic heavy-ion collisions, where quarks and gluons are set free over an extended volume, two species of produced vector (spin-1) mesons, namely φ and K∗0 , emerge with a surprising pattern of global spin alignment. In particular, the global spin alignment for φ is unexpectedly large, while that for K∗0 is consistent with zero. The observed spin-alignment pattern and magnitude for the φ cannot be explained by conventional mechanisms, while a model with strong force fields2, 3 accommodates the current data. This is the first time that the strong force field is experimentally supported as a key mechanism that leads to global spin alignment. We extract a quantity proportional to the intensity of the field of the strong force. Within the framework of the Standard Model, where the strong force is typically described in the quark and gluon language of Quantum Chromodynamics, the field being considered here is an effective proxy description. This is a qualitatively new class of measurement, which opens a new avenue for studying the behaviour of strong force fields via their imprint on spin alignment.

Abdallah, M. S.↗