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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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

rlmolecule: A library for general-purpose material and molecular optimization using AlphaZero-style reinforcement learning

This library includes in-progress code for the optimization of materials and molecules using reinforcement learning. This project seeks to develop a generalized machine learning approach for optimizing targeted, and often complex, functional properties over the space of possible material structures, allowing faster identification of promising candidates. Electronic and transport properties of materials are determined by their molecular structure (for molecules) or their crystal structure (for in-organic crystalline materials). The atomic composition, bonding, and 3-D-spatial arrangement in these systems therefore represent a vast, discontinuous search space for optimal candidates. This library implements AlphaZero style reinforcement learning applied to two worked examples: the optimization of stable organic radicals for redox flow batteries, and the determination of stable electrolyte species for solid state batteries. The current code contains proof-of-concept results run on the Eagle HPC system, while the completed package will be a flexible tool for material optimization across of number of energy-relevant fields, which leverages cloud compute resources for the majority of the computational heavy lifting.

Biagioni, David↗
DOE OSTI2023

Intermediate Temperature Single Component Electrolysis Cell

This project aims at demonstrating a fundamentally new approach towards electrochemical hydrogen production using a single component cell design. Conventional electrolyzer cells consist of a stack of layers (oxygen and fuel electrodes, electrolyte layer) that require multiple processing steps and add to the fabrication cost and complexity. Here we explore the viability of a single-layer electrolyzer device based on the single-layer SOFC concepts described in literature (Asghar et al, 2020). The single layer material is a composite of ionic conductor and catalytic material consisting of ceria doped with Gd and Sm co-processed with CuFe 2 O 4 .

08 HYDROGEN↗
DOE OSTI2019

Effect of formation protocol: Cells containing Si-Graphite composite electrodes

The effect of formation protocol was observed in tests using small pouch cells containing silicon-graphite/Li(Ni 0.5 Mn 0.3 Co 0.2 )O 2 chemistry. The time for the formation protocol was either 13.2 or 186 h for the tested cells. It is demonstrated that the “fast” formation protocol produces cells with similar performance characteristics to that of the “slow” protocol. Moreover, the solid-electrolyte interface layers from both formation protocols are stable and function analogously, albeit with different chemistry. The fast formation protocol may thus allow a more economical route to cell fabrication.

25 ENERGY STORAGE↗
DOE OSTI2026

Heat Transfer Fluids as Co‐Diluents in Localized High‐Concentration Electrolytes for High‐Rate Lithium Metal Batteries With Enhanced Safety

Localized high-concentration electrolytes (LHCEs) have been identified as promising electrolyte formulations for lithium metal batteries, due to their effective interphase formation and promotion of compact Li deposition, yet their practical implementation is often limited by reduced ion transport kinetics. In this study, two industrially established fluorinated ethers are identified for the first time in battery research as effective co-diluents as they combine a broad electrochemical stability window with a low viscosity and intrinsic non-flammability. Incorporating these components, commonly used as heat transfer fluids, yields safer, less flammable electrolyte formulations with enhanced ion mobilities. In particular, the ternary co-diluent formulation shows improved ion mobility by reducing the electrolyte's viscosity while limiting excessive ion clustering. Based on the improved electrolyte transport kinetics, lower overvoltages and higher Coulombic efficiencies at current densities ≥ 1 mA cm −2 are achieved with the ternary co-diluent blend, resulting in markedly extended cycle life in an application-oriented zero-excess pouch cell compared with the baseline system. Complementary electrochemical and ex situ analysis of harvested electrodes at moderate current densities reveals no discernible differences in interphase morphology and composition, suggesting enhanced ion mobility as the primary cause of the improved high-rate performance.

electrolyte diluent↗
DOE OSTI2024

Additive manufacturing of LiCoO 2 electrodes via vat photopolymerization for lithium ion batteries

Additive manufacturing has the potential to revolutionize the fabrication of lithium-ion batteries for a diversity of applications including in portable, biomedical, aerospace, and the transportation fields. Standard commercial batteries consist of stacked layers of various components (current collectors, cathode, anode, separator and electrolyte) in a two-dimensional manner. By leveraging the latest advances in additive manufacturing and computer-aided design, an improved geometric and electrochemical configuration of these batteries can maximize energy efficiency while allowing design optimization to reduce dead space for a given application. In this work, a composite UV photosensitive resin was prepared and used as feedstock in a vat photopolymerization system. The resin was loaded with LiCoO 2 acting as electrochemically active material for the cathode of a lithium-ion battery, and was further improved with the addition of conductivity-enhancing carbonaceous additives. Challenges to additive manufacturing arise from the opacity and high viscosity of the composite nature of these electrochemically-active resins, which cause light refraction during selective UV curing. Subsequently, items were printed and subjected to a thermal post-processing step to obtain an adequate compromise between electrochemical performance and mechanical integrity. Both sintered and green state 3D printed cathodes were assembled into half-cell lithium-ion batteries using lithium metal as a reference and counter electrode. Electrochemical cycling of these batteries yielded satisfactory results approaching commercial LiCoO 2 cathodes’ performance, with the potential advantages of additive manufacturing – high surface area anode–cathode configurations for power performance as well as shape conformability.

25 ENERGY STORAGE↗
DOE OSTI2023

Unveiling a high capacity multi-redox (Nb 5+ /Nb 4+ /Nb 3+ ) NASICON-Nb 2 (PO 4 ) 3 anode for Li- and Na-ion batteries

Sodium superionic conductor (NASICON)-type materials are widely explored as Li- and Na-ion cathodes and solid-state electrolytes but are largely ignored as anodes due to their lower capacities and higher intercalation voltages, which reduce the overall energy densities of Li- and Na-ion batteries (LIBs and SIBs). Herein, we unveil high capacity multi-redox empty NASICON-Nb 2 (PO 4 ) 3 as a potential anode material for LIBs and SIBs, which reversibly delivers 167 and 150 mA h g -1 at the average voltages of 1.86 V vs. Li + /Li 0 and 1.46 V vs. Na + /Na 0 , respectively. The Li and Na intercalation reactions proceed via multiple phase transitions, leading to short-range ordered Li 3 Nb 2 (PO 4 ) 3 and triclinic (P$\overline{1}$ with combining macron]) Na 3 Nb 2 (PO 4 ) 3 , as revealed by in situ X-ray diffraction studies. Our density functional theory calculations are also in agreement with the in situ measurements in predicting a stable Na 3 Nb 2 (PO 4 ) 3 composition in the Na–Nb 2 (PO 4 ) 3 pseudo-binary system. X-ray absorption spectroscopy confirms the participation of multi-redox Nb 5+ /Nb 4+ /Nb 3+ couples. The Nb 2 (PO 4 ) 3 anode delivers capacities greater than 124 and 106 mA h g -1 at 1C rate in Li and Na cells, respectively. In conclusion, pairing Nb 2 (PO 4 ) 3 with suitable cathodes and electrolytes can lead to high energy density batteries.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

The apparent reversal of the Law of Mass Action in concentrated multicomponent aqueous solutions

Although it is well known that aqueous electrolyte solutions behave non-ideally, few are so non-ideal that adding an electrolyte to a saturated solution with a common ion enhances rather than depresses solubility. Nonetheless, this apparent reversal of the Law of Mass Action (LMA) has been observed in simple nitrate solutions at high concentrations. A leading hypothesis is that ion clusters are formed and stabilized by ions having different charge densities. We report the present study examines this concept, in part by reviewing relevant data from multicomponent aqueous solutions containing sodium nitrate (NaNO 3 ), sodium nitrite (NaNO 2 ), sodium hydroxide (NaOH), and sodium aluminate (NaAl(OH) 4 ) - the major constituents in alkaline nuclear waste. Here, NaOH and NaAl(OH) 4 did not enhance the solubility of NaNO 3 or NaNO 2 , whereas NaNO 2 and NaNO 3 enhanced rather than depressed the solubility of each other despite each having the sodium cation (Na + ) in common. Solutions evaluated in this study have more than 20 molal total Na + concentration, and most have less than one mole of water per mole of ion. Thus, this reversal of the LMA occurs in solutions where there is not enough water to fully hydrate the ions, pointing to the importance of ion cluster formation. Within the composition range of the solutions analyzed here, this reversal of the LMA occurs regardless of NaAl(OH) 4 and NaOH concentrations. Elevated temperatures also result in the reversal of the LMA in the subsystems NaNO 2 -NaNO 3 -H 2 O and NaOH-NaNO 3 -H 2 O, consistent with spectroscopic and computational studies showing enhanced interactions at higher temperatures. Although speciation in these highly concentrated electrolyte solutions is not well understood, the stabilization of ion clusters by: (i) optimizing charge density around the ions through different combinations of mixed cations and anions in solution; and (ii) high temperatures where ions experience prolonged contact, offers important clues for future research into how these species control solubility.

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

Coupling Amorphization and Compositional Optimization of Ternary Metal Phosphides toward High-Performance Electrocatalytic Hydrogen Production

Amorphous materials, with abundant active sites and unique electronic configurations, have the potential to outperform their crystalline counterparts in high-performance catalysis for clean energy. However, their synthesis and compositional optimization remain underexplored due to the strict conditions required for their formation. Here, in this study, we report the synthesis of ternary platinum-nickel-phosphorus (PtNiP) amorphous nanoparticles (ANPs) within milliseconds by flash Joule heating, which features ultrafast cooling that enables the vitrification of metal precursors. Through compositional optimization, the Gibbs free energy of hydrogen adsorption for Pt 4 Ni 4 P 1 ANPs is optimized at 0.02 eV, an almost ideal value, even surpassing that of the benchmark metallic platinum catalyst. As a result, the PtNiP ANPs exhibited superior activity in electrocatalytic hydrogen evolution in acid electrolyte (η 10 ∼ 14 mV, Tafel slope ∼ 18 mV dec –1 , and mass activity 5× higher than state-of-the-art Pt/C). Life-cycle assessment and technoeconomic analysis suggest that, compared to existing processes, our approach enables notable reductions in greenhouse gas emission, energy consumption, and production cost for practical electrolyzer catalyst manufacturing.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Surface-functionalized silicon anode for high energy lithium ion batteries

A composition includes a silicon nanoparticle having surface-attached groups, and the silicon nanoparticle is represented by the formula: [Si]-[linker]-[terminal group]. In the formula [Si] represents the surface of the silicon nanoparticle; [terminal group] is a moiety that is configured for further reaction or is compatible with the electrolyte; and [linker] is a group linking the surface of the silicon nanoparticle to the [terminal group].

Zhang, Zhengcheng↗
DOE OSTI2020

Mesoporous nickel-iron-manganese-alloy based metal/metal oxide composite thick film catalysts

Selective alloy corrosion is used to synthesize a robust and ultrafine mesoporous NiFeMn-based metal/metal oxide oxygen evolving catalyst with ligament and pore sizes in the range of 10 nm and a BET surface area of 43 m2/g. As an oxygen evolving catalyst, the mesoporous catalyst exhibits high stability (>264 hours) at a high current density (500 mA/cm2) with a low overpotential (360 mV) using a moderate electrolyte concentration (1 M KOH). The catalyst is made from non-precious metals and its fabrication is straight forward and directly applicable to large-scale synthesis.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Intercalation of Mg into a Few-Layer Phyllomanganate in Non-aqueous Electrolytes at Room Temperature

The use of oxide cathodes in Mg batteries would unlock a potential energy storage system that delivers high-energy density. However, poor kinetics of Mg diffusion in known solid oxide lattices strongly limits reversible intercalation, which motivates the sustained exploration of new candidates. Herein, nanocrystals of a few-layer phyllomanganate, reminiscent of the mineral vernadite, were shown to have considerable electrochemical activity toward Mg intercalation at room temperature, where it delivered similar to 190 mAh g- 1 at similar to 1.9 V (vs Mg/Mg 2+ ) in batteries paired with a Mg metal anode. Multimodal characterization confirmed the notable degree of reversible intercalation by probing the structural, compositional, and redox changes undertaken by the oxide. Distinct levels of Mg activity were also observed while varying the content of small amounts of lattice water and the temperature of the reaction. The results reaffirm the prospects for operational Mg batteries using oxide cathode in moderate conditions, overcoming current limits of performance of this prospective technology.

25 ENERGY STORAGE↗
DOE OSTI2021

Water and Solute Activities Regulate CO 2 Reduction in Gas-Diffusion Electrodes

Electrolysis of CO 2 at gas-diffusion electrodes (GDEs) has typically been limited by the supply of gas to the electrocatalyst, overshadowing the importance of the supply of water. However, at high current densities that approach 1 A cm –2 , where the electrolyte becomes highly concentrated in the catalyst layer of a GDE, the activity of water and solutes deviate from their bulk dilute solution values, potentially slowing reaction rates and changing reaction equilibrium potentials. In addition, as flow plates for the gas stream are introduced to enable larger electrodes and high single pass conversion of CO 2 to product, variations in the gas composition will become important. By drawing upon literature for the oxygen reduction reaction (ORR), here we explain how to account for these effects in future modeling and experimental work, with particular attention to accurate use of the Nernst equation for electrode potentials and the Arrhenius equation for reaction rates. Specifically, using measurements of KOH solvent and solute activity reported in literature, and assuming the second protonation of CO 2 by water as the rate-determining step, we show the Nernst equation dilute-solution approximation of the CO 2 to CO equilibrium potential to be accurate below 5 M KOH, but it has a 74 mV error when increasing the concentration up to 10 M KOH. Finally, a simple one-dimensional model of a serpentine flow-field on a GDE demonstrated that a reactor with constant pressure of 1 bar and 1 A cm –2 at the inlet had only ~0.3 A cm –2 at the outlet for a conversion in CO 2 partial pressure from 0.90 to 0.48 bar, showing the significant practical implications of this work.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Dissolution and initial hydration behavior of tricalcium aluminate in low activity sulfate solutions

Influences of alkali or alkaline earth sulfates on the hydration of cubic tricalcium aluminate (C 3 A) were evaluated by in situ dissolution rate measurements, by ex situ near-surface composition measurements with secondary ion mass spectrometry, and by in situ synchrotron X-ray diffraction to monitor precipitation of hydration products. Both slight reductions in dissolution rate and cation-specific interactions with the solid were observed. The near-surface Ca/Al ratio is significantly lower after some dissolution and the electrolyte cations are incorporated within the surface with different affinities (Mg 2+ > K + > Na + ). An interfacial dissolution-reprecipitation mechanism may explain the observations as well as, or better than, a simple cation exchange. The sulfate concentration in solution affects the rates of both C 3 A dissolution and precipitation of hydration products. Aditionally, sulfate ions likely adsorb at the hydrous Al-rich surface layer, thereby reducing the dissolution rate of aluminates and delaying the precipitation of aluminate hydration products.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Floating zone crystal growth, structure, and properties of a cubic Li 5.5 La 3 Nb 1.5 Zr 0.5 O 12 garnet-type lithium-ion conductor

As a promising candidate for solid-state electrolytes in Li-ion batteries, the garnet-type Li-ion conductor series Li 5+x La 3 Nb 2-x Zr x O 12 (LLNZO) (0 ≤ x ≤ 2) exhibits high ionic conductivity at room temperature. However, no previous single-crystal growth or characterization has been reported for LLNZO compositions 0 ≤ x ≤ 1. To obtain a complete understanding of the trend in the structure–property relationship in this class of materials, we used the floating zone (FZ) method to grow a single crystal of Li 5.5 La 3 Nb 1.5 Zr 0.5 O 12 that was 4 mm in diameter and 10 mm in length. Using Laue neutron single-crystal diffraction, two distinct Li sites were observed: tetrahedral 24d and octahedral 96h sites. The maximum entropy method (MEM) based on neutron single-crystal diffraction data was used to map Li nuclear density and estimate that the bottleneck of Li transport exists between neighboring tetrahedral and octahedral sites, and that Li is delocalized between split octahedral sites. Room-temperature Li-ion conductivity in Li 5.5 La 3 Nb 1.5 Zr 0.5 O 12 measured with electrochemical impedance spectroscopy (EIS) was 1.37 × 10 -4 S cm -1 . The Li migration activation energy was estimated to be 0.50 eV from EIS and 0.47 eV from dielectric relaxation measurements. The Li-ion jump attempt rate was estimated to be 1.47 × 10 12 Hz while the time scale of successful migration is 10 -7 to 10 -6 s.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Doping- and Strain-Dependent Electrolyte-Gate-Induced Perovskite to Brownmillerite Transformation in Epitaxial La 1– x Sr x CoO 3–δ Films

Much recent attention has focused on the voltage-driven reversible topotactic transformation between the ferromagnetic metallic perovskite (P) SrCoO 3-δ and oxygen-vacancy-ordered antiferromagnetic insulating brownmillerite (BM) SrCoO 2.5 . This is emerging as a paradigmatic example of the power of electrochemical gating (using, e.g., ionic liquids/gels), the wide modulation of electronic, magnetic, and optical properties generating clear application potential. SrCoO 3 films are challenging with respect to stability, however, and there has been little exploration of alternate compositions. Here, we present the first study of ion-gel-gating-induced P. BM transformations across almost the entire La 1-x SrxCoO 3 phase diagram (0 ≤ x ≤ 0.70), under both tensile and compressive epitaxial strain. Electronic transport, magnetometry, and operando synchrotron X-ray diffraction establish that voltage-induced P → BM transformations are possible at essentially all x, including x ≤ 0.50, where both P and BM phases are highly stable. Under small compressive strain, the transformation threshold voltage decreases from approximately +2.7 V at x = 0 to negligible at x = 0.70. Both larger compressive strain and tensile strain induce further threshold voltage lowering, particularly at low x. The P → BM threshold voltage is thus tunable, via both composition and strain. At x = 0.50, voltage-controlled ferromagnetism, transport, and optical transmittance are then demonstrated, achieving Curie temperature and resistivity modulations of similar to 220 K and at least 5 orders of magnitude, respectively, and enabling estimation of the voltage-dependent Co valence. The results are analyzed in the context of doping- and strain-dependent oxygen vacancy formation energies and diffusion coefficients, establishing that it is thermodynamic factors, not kinetics, that underpin the decrease in the threshold voltage with x, that is, with increasing formal Co valence. These findings substantially advance the practical and mechanistic understanding of this voltage-driven transformation, with fundamental and technological implications.

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

Synthesis of Fluorine-Doped Lithium Argyrodite Solid Electrolytes for Solid-State Lithium Metal Batteries

Solid-state lithium metal batteries (SSLMBs) that utilize novel solid electrolytes (SEs) have garnered much attention because of their potential to yield safe and high-energy-density batteries. Sulfide-based argyrodite-class SEs are an attractive option because of their impressive ionic conductivity. Recent studies have shown that LiF at the interface between Li and SE enhances electrochemical stability. However, the synthesis of F-doped argyrodites has remained challenging because of the high temperatures used in the state-of-the-art solid-state synthesis methods. In this work, for the f irst time, we report F-doped Li 5+y PS 5 F y argyrodites with a tunable doping content and dual dopants (F-/Cl- and F-/Br-) that were synthesized through a solvent-based approach. Among all compositions, Li 6 PS 5 F 0.5 C l0.5 exhibits the highest Li-ion conductivity of 3.5 x 10 -4 S cm -1 at room temperature (RT). Furthermore, Li symmetric cells using Li 6 PS 5 F 0.5 Cl 0.5 show the best cycling performance among the tested cells. X-ray photoelectron spectroscopy and ab initio molecular dynamics simulations revealed that the enhanced interfacial stability of Li 6 PS 5 F 0.5 C l0.5 SE against Li metal can be attributed to the formation of a stable solid electrolyte interphase (SEI)-containing conductive species (Li 3 P), alongside LiCl and LiF. These findings open new opportunities to develop high-performance SSLMBs using a novel class of F-doped argyrodite electrolytes.

25 ENERGY STORAGE↗
DOE OSTI2021

A Sodium–Antimony–Telluride Intermetallic Allows Sodium-Metal Cycling at 100% Depth of Discharge and as an Anode-Free Metal Battery

In this work, repeated cold rolling and folding is employed to fabricate a metallurgical composite of sodium–antimony–telluride Na 2 (Sb 2/6 Te 3/6 Vac 1/6 ) dispersed in electrochemically active sodium metal, termed “NST-Na.” This new intermetallic has a vacancy-rich thermodynamically stable face-centered-cubic structure and enables state-of-the-art electrochemical performance in widely employed carbonate and ether electrolytes. NST-Na achieves 100% depth-of-discharge (DOD) in 1 m NaPF 6 in G2, with 15 mAh cm –2 at 1 mA cm –2 and Coulombic efficiency (CE) of 99.4%, for 1000 h of plating/stripping. Sodium-metal batteries (SMBs) with NST-Na and Na 3 V 2 (PO 4 ) 3 (NVP) or sulfur cathodes give significantly improved energy, cycling, and CE (>99%). An anode-free battery with NST collector and NVP obtains 0.23% capacity decay per cycle. Imaging and tomography using conventional and cryogenic microscopy (Cryo-EM) indicate that the sodium metal fills the open space inside the self-supporting sodiophilic NST skeleton, resulting in dense (pore-free and solid electrolyte interphase (SEI)-free) metal deposits with flat surfaces. The baseline Na deposit consists of filament-like dendrites and “dead metal”, intermixed with pores and SEI. Density functional theory calculations show that the uniqueness of NST lies in the thermodynamic stability of the Na atoms (rather than clusters) on its surface that leads to planar wetting, and in its own stability that prevents decomposition during cycling.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Fully‐Printed Ion Sensor Arrays for Measuring Agricultural Nitrogen and Potassium Concentrations Using Nernstian and AI Models

Abstract The chemical composition of growing media is a key factor for plant growth, impacting agricultural yield and sustainability. However, there is a lack of affordable chemical sensors for ubiquitous nutrient ion monitoring in agricultural applications. This work investigates using fully printed ion‐sensor arrays to measure the concentrations of nitrate, ammonium, and potassium in mixed‐electrolyte media. Ion sensor arrays composed of nitrate, ammonium, and potassium ion‐selective electrodes and a printed silver‐silver chloride (Ag/AgCl) reference electrode are fabricated and characterized in aqueous solutions in a range of concentrations that encompass what is typical for agricultural growing media (0.01 m m –1 m ). The sensors are also tested in mixed‐electrolyte solutions of NaNO 3 , NH 4 Cl, and KCl of varying concentrations, and the recorded potentials are input into Nernstian and artificial neural network models to compare the prediction accuracy of the models against ground truth. The artificial neural network models demonstrated higher accuracy over the Nernstian model, and the model using only ion‐sensor inputs is 7.5% more accurate than the Nernstian model under the same conditions. By enabling more precise and efficient fertilizer application, these sensor arrays coupled to computational models can help increase crop yields, optimize resource use, and reduce environmental impact.

Goodrich, Payton [University of California Berkele↗