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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 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Elucidating the Solvation Structures and Dynamics in Iron-Based TFSI – Aqueous Systems

This study investigates the solvation structures and dynamics of bis(trifluoromethanesulfonyl)imide (TFSI – )-based aqueous electrolytes, focusing on Fe(TFSI) 2 and Fe(TFSI) 3 . Using advanced characterization techniques, including small-angle X-ray scattering, molecular dynamics simulations, Raman spectroscopy, Fourier-transform infrared spectroscopy, and nuclear magnetic resonance, we elucidate how the electrolyte concentration influences ion association, solvation structures, and transport properties. Furthermore, our findings show that higher electrolyte concentrations promote the formation of contact ion pairs and anion networks, leading to reduced ion mobility and altered hydrogen-bonding dynamics. These insights provide a deeper understanding of solvation phenomena in TFSI-based electrolytes and contribute to the development of efficient and environmentally friendly iron electrodeposition processes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Rechargeable Zinc Alkaline Anodes for Long-Cycle Energy Storage

Zinc alkaline anodes command significant share of consumer battery markets and are a key technology for the emerging grid-scale battery market. Improved understanding of this electrode is required for long-cycle deployments at kWh and MWh scale due to strict requirements on performance, cost, and safety. For this article, we give a modern literature survey of zinc alkaline anodes with levelized performance metrics and also present an experimental assessment of leading formulations. Long-cycle materials characterization, performance metrics, and failure analysis are reported for over 25 unique anode formulations with up to 1500 cycles and ~1.5 years of shelf life per test. Statistical repeatability of these measurements is made for a baseline design (fewest additives) via 15 duplicates. Baseline design capacity density is 38 mAh per mL of anode volume, and lifetime throughput is 72 Ah per mL of anode volume. We then report identical measurements for anodes with improved material properties via additives and other perturbations, some of which achieve capacity density over 192 mAh per mL of anode volume and lifetime throughput of 190 Ah per mL of anode volume. Novel in operando X-ray microscopy of a cycling zinc paste anode reveals the formation of a nanoscale zinc material that cycles electrochemically and replaces the original anode structure over long-cycle life. Ex situ elemental mapping and other materials characterization suggest that the key physical processes are hydrogen evolution reaction (HER), growth of zinc oxide nanoscale material, concentration deficits of OH – and ZnOH 4 2– , and electrodeposition of Zn growths outside and through separator membranes.

25 ENERGY STORAGE↗
DOE OSTI2022

Anion Effects on the Interfacial Structure and Bulk Physical Properties in Choline-Based Hydrogen-Bonded Electrolytes

Electrolytes consisting of choline (Ch) salts with acetate (Ac) and oxalate (Ox) anions were studied in mixtures with ethylene glycol (EG), in comparison to chloride (Cl)- and bis(trifluorosulfonyl)imide (TFSI)-containing systems to understand the impact of anion size and charge density on the bulk electrolyte and interfacial properties. These represent hydrogen-bonded concentrated electrolytes where the Ch salts are the H-bond acceptors (HBAs) and EG is the H-bond donor (HBD) in 1:2 and 1:4 HBA:HBD ratios. Increased H-bonding in Ch 2 Ox with EG compacts the liquid compared to ChAc, consistent with the increased dissociation energies of the HBA:HBD clusters with Ox –2 calculated by density functional theory (DFT), thus leading to denser and more viscous liquids. Electrochemical impedance spectroscopy (EIS) and surface-enhanced Raman spectroscopy (SERS) were used to investigate interfacial charge density and the electrode surface species. Differential capacitance curves demonstrate weak dependence on potential except for ChAc:EG, where Ac – is found to adsorb on the Au surface, in particular at +0.055 V vs Ag quasi-reference while no specific adsorption was observed on glassy carbon (GC). In situ SERS measurement confirms the formation of a surface layer in the ChAc:EG systems resulting from a Au–acetate interaction. Despite the structural similarities, Ox –2 did not show specific binding or any dependence of capacitance on potential as a result of strongly solvating EG molecules via H-bonds. Furthermore, this study shows that the charge density of the HBAs impacts both bulk properties and the electrical double-layer formation in concentrated H-bonded electrolytes that is relevant to electrochemical kinetics and morphology in electrodeposition processes and energy storage applications.

25 ENERGY STORAGE↗
DOE OSTI2025

Interfacial Properties of Gold and Cobalt Oxyhydroxide in Plasmon-Mediated Oxygen Evolution Reaction

Water electrolysis is one green approach of storing electrical energy within chemical bonds of the high-energy hydrogen gas (H2). The anodic reaction involved in the oxygen evolution reaction (OER) requires high kinetic overpotential on the overall rate of the process. Recently, plasmonic gold nanoparticles (Au NPs) have been added to enhance the charge transfer at the interface of the OER electrocatalysts and electrolyte under light illumination. However, mechanistic understanding of how Au NPs on the photo-assisted electrochemical process is still lacking. We applied a model system of plasmonic Au electrode and a cobalt (Co)-based OER electrocatalyst in alkaline electrolytes to investigate the plasmon-mediated OER process with (photo)electrochemical and spectroscopic studies. Our results demonstrated that the electrodeposited and surfactant-free plasmonic Au electrode could enhance the electrocatalytic performances of the Co-based electrocatalysts in the OER process with continuous visible and near infrared light illumination. Both the photothermal and energetic charge carriers were found to contribute to the enhanced OER performance based on the transient photocurrent studies, and the interfaces of Au and the Co-based electrocatalysts determined the enhancement mechanisms. The active phase of the cobalt based OER electrocatalyst at operating potentials was identified with electrochemical Raman measurements.

OER↗
DOE OSTI2015

Improvement of Electrochemical Properties of Lithium–Oxygen Batteries Using a Silver Electrode

Silver (Ag) electrodes are prepared by an electrodeposition method at -0.25 V versus SCE. To evaluate the effect of particle size on Li–air cells, deposition times are 3, 10, 30, and 300 s. When cycled at a current density of 0.032 mA cm–2, the Ag-deposited electrode for 300 s shows very low polarization corresponding to the oxygen evolution reaction potential at 3.6 V. X-ray diffraction studies confirm that the main discharge product is Li2O2, and the results of scanning electron microscopy and transmission electron microscopy of the discharged electrodes show lithium peroxides at different positions due to the limitation of active sites on silver particles.

25 ENERGY STORAGE↗
DOE OSTI2016

Self-Supported Copper Oxide Electrocatalyst for Water Oxidation at Low Overpotential and Confirmation of Its Robustness by Cu K-edge X-ray Absorption Spectroscopy

Developing efficient water oxidation catalysts made of earth-abundant elements is a demanding challenge that should be met to fulfill the promise of water splitting for clean energy. Herein we report an annealing approach to synthesize binder-free, self-supported heterogeneous copper oxide (CuO) on conductive electrodes for oxygen evolution reaction (OER), producing electrodes with excellent electrocatalytic properties such as high efficiency, low overpotential, and good stability. The catalysts were grown in situ on fluorine-doped tin oxide (FTO) by electrodeposition from a simple Cu(II) salt solution, followed by annealing at a high temperature. Under optimal conditions, the CuO-based OER catalyst shows an onset potential of <0.58 V (vs Ag/AgCl) in 1.0 M KOH at pH 13.6. From the Tafel plot, the required overpotentials for current densities of 0.1 and 1.0 mA/cm2 are only 360 and 430 mV, respectively. The structure and the presence of a CuO motif in the catalyst have been identified by high-energy X-ray diffraction (HE-XRD), Cu K-edge X-ray absorption (XAS) spectra including X-ray absorption near-edge structure (XANES), and extended X-ray absorption fine structure (EXAFS). To the best of our knowledge, this represents the best catalytic activity for CuO-based OER catalysts to date.

Liu, Xiang↗
DOE OSTI2019

Spontaneous Formation of >90% Optically Transmissive, Electrochemically Active CoP Films for Photoelectrochemical Hydrogen Evolution

Earth-abundant catalysts for the hydrogen-evolution reaction need increased mass loadings, relative to Pt films, to achieve comparable activity and stability in acidic electrolytes. We report herein that spontaneous nanostructuring of opaque, electrodeposited CoP films, 40–120 nm in thickness, leads to transparent electrocatalyst films that exhibit up to 90% optical transmission in the visible spectrum. The photocurrent density under simulated sunlight at a representative n + p-Si(100)/CoP photocathode increases by 200% after exposure to 0.50 M H 2 SO 4 (aq) and remains stable for 12 h of continuous operation. Atomic force microscopy and scanning electron microscopy of the film before and after exposure to 0.50 M H 2 SO 4 (aq) validate an optical model for transparent CoP films as probed with spectroscopic ellipsometry.

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

Fractal Model for Drag Reduction on Multiscale Nonwetting Rough Surfaces

Rough surfaces in contact with a flow of fluid exhibit alternating no-slip and free shear boundary conditions at the solid–liquid and air–liquid interfaces, respectively, thereby potentially offering drag reduction benefits. The balance between the dynamic pressure in the flow and the restoring capillary pressure in the interasperity spaces determines the stability of the Cassie state of wettability and is a function of the relative extent of no-slip and free shear regions per unit surface area. In the present study, using a fractal representation of rough surface topography, an analytical model is developed to quantify the stability of the Cassie state of wettability as well as drag reduction and the friction factor for laminar flow in a rectangular channel between nonwetting multiscale rough surfaces. A systematic study is conducted to quantify the effects of fractal parameters of the surfaces and the flow Reynolds number on drag reduction and the friction factor. The studies are used to develop friction factor curves extending the classical Moody diagram to hydrophobic and superhydrophobic surfaces. On the basis of the studies, regime maps are derived for estimating the extent of drag reduction offered by hydrophobic and superhydrophobic surfaces, revealing that superhydrophobic surfaces do not always offer the best drag reduction performance. The application of the fractal model to practical topographies of nonwetting surfaces of copper, aluminum, and zinc oxide fabricated via electrodeposition and etching is also discussed.

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

Long-Term Static and Dynamic Corrosion Stability of Nonwetting Surfaces

Superhydrophobic surfaces (SHSs) and lubricant-infused surfaces (LISs) are two classes of nonwetting surfaces that have drawn attention due to their advanced functional properties including corrosion inhibition. Yet there is a conspicuous lack of corrosion study of SHSs and LISs with respect to their fabrication and material parameters, especially at high temperatures and under dynamic flow conditions over long durations, which is sought to be addressed in this article. Considering copper SHSs and LISs, a full factorial combinatorial study of two facile texturing processes, electrodeposition and etching, two different functionalization agents, stearic acid and mercaptan, and two types of infused lubricants, Krytox 104 and DOWSIL 510, is presented, encompassing over 650 measurements on 90 tested surfaces. All fabricated surfaces demonstrated water repellency with a contact angle above 150° and a sliding angle below 7°. For the first time, the study examines high-temperature corrosion stability and long-term corrosion durability of the nonwetting surfaces in both static fluid and dynamic turbulent flow conditions over a period of 30 days. Here, LISs and SHSs are shown to provide excellent corrosion inhibition over all tested corrosion conditions, with negligible presence of corrosion species on the surfaces and no deterioration of the texturing. The surfaces are also shown to rejuvenate easily to the initial wettability and corrosion resistance values. This study provides valuable insights into the selection of materials and processing parameters for the fabrication of nonwetting surfaces for the application of interest.

Copper↗
DOE OSTI2017

Supercharging a MnO 2 Nanowire: An Amine-Altered Morphology Retains Capacity at High Rates and Mass Loadings

The influence of hexamethylenetetraamine (HMTA) on the morphology of $δ$-MnO 2 and its properties for electrical energy storage are investigated—specifically for ultrathick $δ$-MnO 2 layers in the micron scale. Planar arrays of gold@$δ$-MnO 2 , core@shell nanowires, were prepared by electrodeposition with and without the HMTA and their electrochemical properties were evaluated. HMTA alters the MnO 2 in three ways: First, it creates a more open morphology for the MnO 2 coating, characterized by “petals” with a thickness of 6 to 9 nm, rather than much thinner $δ$-MnO 2 sheets seen in the absence of HMTA. Second, the electronic conductivity of the $δ$-MnO 2 is increased by an order of magnitude. Third, $δ$-MnO 2 prepared in HMTA shows a (001) interlayer spacing that is expanded by ≈30% possibly accelerating Li transport. The net effect of “HTMA doping” is to dramatically improve high rate performance, culminating in an increase in the specific capacity for the thickest MnO 2 shells examined here by a factor of 15 at 100 mV/s.

36 MATERIALS SCIENCE↗
DOE OSTI2020

3D Nanomagnetism in Low Density Interconnected Nanowire Networks

Free-standing, interconnected metallic nanowire networks with densities as low as 40 mg/cm 3 have been achieved over centimeter-scale areas, using electrodeposition into polycarbonate membranes that have been ion-tracked at multiple angles. Networks of interconnected magnetic nanowires further provide an exciting platform to explore 3-dimensional nanomagnetism, where their structure, topology, and frustration may be used as additional degrees of freedom to tailor the materials properties. New magnetization reversal mechanisms in cobalt networks are captured by the first-order reversal curve method, which demonstrate the evolution from strong demagnetizing dipolar interactions to intersection-mediated domain wall pinning and propagation, and eventually to shape-anisotropy dominated magnetization reversal. These findings open up new possibilities for 3-dimensional integrated magnetic devices for memory, complex computation, and neuromorphics.

36 MATERIALS SCIENCE↗
DOE OSTI2021

An Anode-Free Zn–MnO 2 Battery

Aqueous Zn-based batteries are attractive because of the low cost and high theoretical capacity of the Zn metal anode. However, the Zn-based batteries developed so far utilize an excess amount of Zn (i.e., thick Zn metal anode), which decreases the energy density of the whole battery. In this study, we demonstrate an anode-free design (i.e., zero-excess Zn), which is enabled by employing a nanocarbon nucleation layer. Electrochemical studies show that this design allows for uniform Zn electrodeposition with high efficiency and stability over a range of current densities and plating capacities. Using this anode-free configuration, we showcase a Zn–MnO 2 battery prototype, showing 68.2% capacity retention after 80 cycles. Our anode-free design opens a new direction for implementing aqueous Zn-based batteries in energy storage systems.

25 ENERGY STORAGE↗
DOE OSTI2015

In-situ Mass Spectrometric Determination of Molecular Structural Evolution at the Solid Electrolyte Interphase in Lithium-Ion Batteries

Dynamic molecular evolution at solid/liquid electrolyte interface is always a mystery for a rechargeable battery due to the challenge to directly probe/observe the solid/liquid interface under reaction conditions, which in essence appears to be similarly true for all the fields involving solid/liquid phases, such as electrocatalysis, electrodeposition, biofuel conversion, biofilm, and biomineralization, We use in-situ liquid secondary ion mass spectroscopy (SIMS) for the first time to directly observe the molecular structural evolution at the solid electrode/liquid electrolyte interface for a lithium (Li)-ion battery under dynamic operating conditions. We have discovered that the deposition of Li metal on copper electrode leads to the condensation of solvent molecules around the electrode. Chemically, this layer of solvent condensate tends to deplete the salt anion and with low concentration of Li+ ions, which essentially leads to the formation of a lean electrolyte layer adjacent to the electrode and therefore contributes to the overpotential of the cell. This unprecedented molecular level dynamic observation at the solid electrode/liquid electrolyte interface provides vital chemical information that is needed for designing of better battery chemistry for enhanced performance, and ultimately opens new avenues for using liquid SIMS to probe molecular evolution at solid/liquid interface in general.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2022

Polymer-Stabilized Liquid Metal Nanoparticles as a Scalable Current Collector Engineering Approach Enabling Lithium Metal Anodes

Dendrites and dead lithium formation over prolonged cycling have long been challenges that hinder the safe implementation of metallic Li anodes. In this study, we employ polymer-stabilized liquid metal nanoparticles (LM-P NPs) of eutectic gallium indium (EGaIn) to create uniform Li nucleation sites enabling homogeneous lithium electrodeposition. Block copolymers of poly(ethylene oxide) and poly(acrylic acid) (PEO-b-PAA) were grafted onto the EGaIn surface, forming stabilized, well-dispersed NPs. Using a scalable spray coating approach, LM-P NPs were fabricated on copper current collectors, providing lithiophilic PEO sites and interactive carboxyl groups to guide Li deposition. The Li-EGaIn alloying process greatly reduced the Li + diffusion barrier, enabling fast Li transport through the coating layer, resulting in decreased nucleation overpotential. Therefore, about five times lower Li nucleation overpotential was obtained on the LM-P modified Cu with an optimal composition of the polymers than the bare Cu substrates. DFT computations was used to reveal the binding properties between the LM-P layer and Li. Due to the regulated Li plating/stripping process, as-obtained 30 μm Li anodes paired with LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM8 11 ) with a negative/positive electrode capacity (N/P) ratio ~ 10 exhibited stable cycling performance at 0.5C for over 250 cycles, with an average Coulombic efficiency of 99.55%. Ultrathin Li (1 μm) anodes with an N/P ratio ~ 0.6 were also demonstrated in Li|LiFePO 4 cells, which examined the stabilization of Li by LM-P NPs and monitored practical loadings of Li anodes that are close to anode-free systems.

25 ENERGY STORAGE↗
DOE OSTI2024

Surface-Treated Composite Polymer as a Stable Artificial Solid Electrolyte Interphase Layer for Lithium Metal Anodes

Lithium (Li) metal batteries (LMBs) are one of the most promising high energy density batteries to meet the demands of electric transportation. However, the practical applications of LMBs are hindered by short cycle life and safety concern, mainly associated with side reactions between Li metal anode and liquid electrolyte and the growth of Li dendrites during cycling. In this study, we develop a stable artificial solid electrolyte interphase (aSEI), which consists of a surface-treated (S T ) PEO–Li 6.4 Ga 0.2 La 3 Zr 2 O 12 composite polymer coating layer (CPL) on Li metal anode. The developed aSEI is stable against selected electrolyte and enables a uniform electrodeposition of Li. Therefore, S T CPL@Li||LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) cells exhibit improved cycling stability compared with bare Li||NMC811 cells at moderate to high current densities. Notably, using a 50 µm thick Li and a practical NMC811 cathode (~4.8 mAh cm -2 ), a capacity retention of 85% is obtained for S T CPL@Li||NMC811 cells at a current density of 2.4 mAcm -2 after 300 cycles compared with 24% for bare Li||NMC811 cells. Furthermore, S T CPL@Li||NMC811 cells demonstrate higher capacities at charge current densities of 2.4, 4.8 and 7.2 mAcm -2 compared with bare Li||NMC811 cells. Further, these findings suggest that S T CPL is promising for high current density practical LMBs.

25 ENERGY STORAGE↗
DOE OSTI2018

Investigation of p-type Ca 2 Fe 2 O 5 as a Photocathode for Use in a Water Splitting Photoelectrochemical Cell

Ca 2 Fe 2 O 5 is a p-type oxide that has not been previously investigated as a photocathode for use in a water splitting photoelectrochemical cell. In this study, Ca 2 Fe 2 O 5 was synthesized as a polycrystalline electrode, and its properties relevant to photoelectrochemical hydrogen production were investigated. Ca 2 Fe 2 O 5 electrodes were prepared by thermally annealing electrodeposited FeOOH films with a solution of Ca(NO 3 ) 2 drop-casted onto the electrode surface. The bandgap energy, band edge positions, flatband potential, photocurrent generation, and chemical and photoelectrochemical stabilities of Ca 2 Fe 2 O 5 were examined. The results showed that Ca 2 Fe 2 O 5 has an ideal bandgap and band positions that can enable the utilization of visible light for overall solar water splitting. Photocurrent-time measurements were also performed and the changes in morphology, crystallinity, and composition of the Ca 2 Fe 2 O 5 electrodes before and after the photocurrent measurement were investigated. Furthermore, this made it possible to examine the photostability of Ca 2 Fe 2 O 5 and elucidate the cause of the observed photocurrent decay.

25 ENERGY STORAGE↗