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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

3D printing of architected sulfur cathodes with dual-site atomic catalysts for accelerated polysulfide kinetics and Li-ion transport in high areal-loading lithium–sulfur batteries

The practical deployment of lithium–sulfur batteries (LSBs) is hindered by fundamental limitations in conventional slurry-cast cathodes, including poor sulfur utilization, sluggish ion transport, and low areal capacity, particularly in thick electrodes required for high energy density. To address these challenges, we present direct ink writing (DIW) as an additive manufacturing strategy to fabricate advanced current-collector-free, 3D-printed sulfur cathodes (3DP S@CoNi-DSACs/NC) with hierarchically porous architectures that enhance lithium-ion diffusion, promote electrolyte penetration, and reduce interfacial resistance. The synergistic effects of Co/Ni dual-atom sites accelerate redox kinetics and mitigate polysulfide shuttling. As a result, the optimized 3DP cathode with a sulfur loading of 5.4 mg cm −2 demonstrated excellent rate capability, delivering a high reversible capacity of 1041.4 mAh g −1 at 1C with 85.5% capacity retention after 1000 cycles, significantly outperforming its cast counterpart. Remarkably, even at a higher sulfur loading of 8.1 mg cm −2 , the 3DP cathode maintains outstanding performance, achieving a discharge capacity of 1538.4 mAh g −1 and an areal capacity of 12.5 mAh cm −2 at 0.1C. This study not only demonstrates the functional integration of catalytically active materials into 3D printable sulfur cathode architectures but also offers a scalable and transformative platform for building high-performance LSBs beyond conventional electrode manufacturing methods.

3D electrode↗
DOE OSTI2024

Accelerating FEM-Based Corrosion Predictions Using Machine Learning

Atmospheric corrosion of metallic parts is a widespread materials degradation phenomena that is challenging to predict given its dependence on many factors (e.g. environmental, physiochemical, and part geometry). For materials with long expected service lives, accurately predicting the degree to which corrosion will degrade part performance is especially difficult due to the stochastic nature of corrosion damage spread across years or decades of service. The Finite Element Method (FEM) is a computational technique capable of providing accurate estimates of corrosion rate by numerically solving complex differential Eqs. characterizing this phenomena. Nevertheless, given the iterative nature of FEM and the computational expense required to solve these complex equations, FEM is ill-equipped for an efficient exploration of the design space to identify factors that accelerate or deter corrosion, despite its accuracy. In this work, a machine learning based surrogate model capable of providing accurate predictions of corrosion with significant computational savings is introduced. Specifically, this work leverages AdaBoosted Decision trees to provide an accurate estimate of corrosion current per width given different values of temperature, water layer thickness, molarity of the solution, and the length of the cathode for a galvanic couple of aluminum and stainless steel.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Townsend to glow discharge transition for a nanosecond pulse plasma in helium: space charge formation and resulting electric field dynamics

Stark polarization spectroscopy is used to investigate the temporal evolution of the electric field distribution in the cathode region of a nanosecond pulsed discharge in helium at 120 Torr. The measurements are performed on the He I transition at 492.19 nm, during the early stages of the discharge formation. The experimental results are compared with the predictions of a 1D fluid model. Time-resolved ICCD images show that the discharge develops as a diffuse, cathode-directed ionization wave with a Townsend-like feature before transitioning into a glow-like structure. Near anode instabilities characterized by filament formation were observed near the high voltage electrode. Within 30 ns, a reduction of the sheath thickness to about 250 μm is observed, coinciding with a gradual increase of the discharge current and proportional increase in electric field at the cathode. Additionally, the cathode electric field corresponding to this sheath with a thickness of 250 μm is about 40 kV cm -1 . A subsequent steep increase of the discharge current leads to a further reduction of the sheath width. The electric field evolution as obtained by the fluid model is in excellent agreement with the measurements and shows that an enhanced ionization near the cathode is causing the space charge formation responsible for the increase in electric field.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Optimization of catholyte for halide-based all-solid-state batteries

Halide solid electrolytes gain significant attention due to their high ionic conductivity, low processing temperature, dry air compatibility, and high-voltage stability. However, low cathode active material (CAM) loading in the composite cathode constrains the realization of high energy density for halide-based all-solid-state batteries. In this study, three halide materials, raw Li 3 YBrCl 5 (LYBC-R, <30μm), milled LYBC (LYBC-M, <5 μm) and freeze-dried Li 3 InCl 6 (LIC, <500 nm), were used as catholytes, combined with LYBC-M as the electrolyte and LiIn alloy as the anode. The CAM:catholyte ratio was investigated as well as stack pressure and operating temperature. Our study demonstrates that particle size of the catholyte plays an important role only for high CAM loading or high C-rate cycling. At moderate CAM loading (65 and 70wt% LiNi 0.83 Mn 0.06 Co 0.11 O 2 ) and 0.1 C-rate, all the three catholytes perform well, providing initial discharge capacities >177 mAh/g. At high CAM loading (85wt%) and 0.1 C-rate, a cathode with the nano-scale LIC catholyte provides discharge capacity of 175 mAh/g, while the larger particle size catholytes suffer significantly reduced capacity. Both LYBC and LIC catholytes provided capacity retention >80% after 200 cycles at 0.5C. These results imply that cathode particle size is critically important for performance at high CAM loading. Furthermore, both electrolyte and cathode were tape cast to scale up size and prepare realistic layer thicknesses. A small amount of binder was used in both layers, to balance the electrochemical performance and mechanical properties. Further, the discharge capacity of a tape cell was 152mA h/g at 0.1C with a capacity retention of 81.8% after 20 cycles at 0.5C. The results demonstrate the excellent performance of LYBC as an electrolyte, and provide guidance for halide-based cathode design.

25 ENERGY STORAGE↗
DOE OSTI2023

Aligned carbon fibers-carbon nanotube-polymer-based composite as lithium-ion battery current collector

High energy density demand is pushing the development of high-voltage cathode materials, which necessitates improved electrochemical stability of other battery components such as binders, electrolytes, and current collectors. Current collectors are considered to be an inactive component but still play an essential role. In this study, a metal-free composite film containing directionally aligned carbon fiber (CF), carbon nanotube (CNT), and polymer (P) was developed to replace aluminum foil as a cathode current collector, which relies on forming an Al 2 O 3 layer to ensure electrochemical stability at high voltage. Here, each component in the new cathode current collector played a functional role. The CNTs provided uniform current densities, and CFs improved the electronic conductivity and mechanical strength of the composite material. The polymer enhanced the adhesion of the cathode coating with the current collector and provided an impervious support to the cathode materials. The CF-CNT-P composite demonstrated excellent electrochemical and thermal stability. Cathodes coated on the CF-CNT-P composite exhibited lower charge transfer resistance, improved rate capability, and improved cyclic stability compared with the cathodes deposited on conventional aluminum foil. Additionally, the composite current collector was lighter (1.81 mg/cm 2 and 15 µm thick) than the commonly used aluminum foil (4.35 mg/cm2 and 15 µm thick), which can increase the cell energy density. Additionally, the CF-CNT-P did not need to be separated from the cathode coating during recycling and can be burnt out with binder, simplifying the recycling process.

25 ENERGY STORAGE↗
DOE OSTI2020

X-ray Nanocomputed Tomography in Zernike Phase Contrast for Studying 3D Morphology of Li–O 2 Battery Electrode

In this work, we investigated the lithium peroxide (Li 2 O 2 ) and pore size distribution in lithium-O 2 battery electrodes at different states of charge using transmission X-ray microscopy coupled with Zernike phase contrast to carry out nano-Computed Tomography. We report that such technique enables, at the nanoscale, to distinguish light elements such as carbon and Li 2 O 2 in Li-O 2 battery cathode electrodes. We verified by wave-propagation simulation that this approach efficiently improves the contrast of images in comparison with the pure absorption. The Li 2 O 2 distribution and thickness, interphases, and pore network are visualized and quantified, which give a valuable insight into our cathode architecture. From this 3D analysis, we highlight modifications of the air-cathode morphology and the Li 2 O 2 spatial organization as well as their potential implication in terms of carbon surface passivation and pore-clogging. After the full recharge process, this technique can also reveal the spatial distribution of the residual Li 2 O 2 and other byproducts.

25 ENERGY STORAGE↗
DOE OSTI2020

Significance of a Solid Electrolyte Interphase on Separation of Anode and Cathode Materials from Spent Li-Ion Batteries by Froth Flotation

The separation of electrode active materials from spent Li-ion batteries (LIBs) by froth flotation is challenging due to the changes in surface properties of electrode active materials from cycling as well as the presence of organic binders. In this work, the froth flotation separation of aged anode and cathode composite materials from spent LIBs was systematically investigated after the materials were heat treated. The results show that aged anode and cathode materials from spent LIBs can be well separated from each other after a heating process in air at 400 degrees C and at which some of the PVDF binder remains intact. The underlying mechanism was investigated by X-ray photoelectron spectroscopy (XPS), contact angle measurements, and scanning transmission electron microscopy (STEM) coupled with energy-dispersive X-ray spectroscopy (EDX). The results from the XPS and contact angle measurements show that there is a hydrophilic and oxygen-rich layer on the surface of aged anode materials. This hydrophilic surface, associated with the solid electrolyte interface (SEI) layer, impacts the froth flotation process significantly. The results also show that both the SEI layers and PVDF binder residues on the surface are removed at 400 degrees C for an hour, restoring the hydrophobicity of the anode materials, which, in turn, benefits the separation of anode and cathode materials. The STEM/EDX elemental analysis data confirms that there are 20 nm-thick oxygen-rich SEI layers on the surfaces, which can be removed after a heating process. The present result illustrates the significance of the SEI layers in flotation separation of electrode materials and sheds new lights into the future development of the recycling processes for the separation of anode and cathode composite materials from spent Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2021

Investigation of Membrane Chemical Degradation as a Function of Catalyst Platinum Loading

Membrane chemical degradation is one of many factors that can impact fuel cell durability. Additionally, the fuel cell’s lifetime heavily depends on the membrane and its ability to maintain chemical and mechanical integrity. Previous studies indicate that chemical degradation is due to the formation of hydroxyl radicals that attack the polymer structure resulting in membrane thinning, pinhole formation, and the release of fluoride and sulfate ions. Membrane durability was investigated using ultra-low Pt electrode loadings (≤ 0.1 mg Pt cm -2 ). Accelerated stress testing (US-DOE protocols) demonstrated that the degradation rate was found to increase with higher Pt loadings. This is most likely due to more heterogeneous sites for radical formation due to hydrogen crossover to the cathode. We also explored membrane degradation rates while varying catalyst layer thickness, ionomer to carbon ratio, and types of carbon support. All of the aforementioned variables impact the membrane degradation rates.

25 ENERGY STORAGE↗
DOE OSTI2021

Predicting Pit Stability On Additively Manufactured SS316 Via Finite Element Modeling [Slides]

Pit growth and repassivation are complex, with many interconnecting geometric and environmental parameters to consider. Experimentally, it is difficult to isolate these individual parameters to study their effect on the stability of pits. To enable these studies, a finite element modeling approach has been developed to allow systematic testing of parameters that impact a pit’s stability. The specific parameters studied were the cathode diameter, the pit diameter and shape, and the water layer thickness. Hemispherical and rectangular-based pits were studied to determine the impact of the overall pit shape. Pit stability results were compared with mathematical calculations based on the Maximum Pit Model, for both 50% saturation and 100% saturated salt film coverage. Further studies expanded the range of pit geometry to those relevant to additively manufactured surfaces.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Ultra-fast and Thick Boriding of Geothermal Casing to Enhance Reliability

Harnessing the heat that is continuously generated underneath the Earth’s crust (geothermal) is a clean and renewable source of energy. Geothermal energy can be used to heat and cool buildings, including greenhouses, and to generate electrical power. Compared to other renewable energy sources such as solar and wind, geothermal energy is more reliable because it is available all the time and versatile in its many forms of application and deployment. Nonetheless, the deployment and extensive use of geothermal energy still lags behind other renewable sources due to some technical, but mainly economic challenges. Upfront costs of geothermal power well development are relatively high. Some of this high cost is attributed to the use of expensive construction materials to ensure adequate performance during operation. For example, Inconel 625, super duplex 2507, and titanium alloy materials are used in downhole casings, piping, and other components exposed to brine solution to withstand harsh operating environments (high temperature and corrosive environments). Relatively low-cost carbon steel can be used in many of these components in geothermal power plants; however, they are susceptible to excessive corrosion, thereby limiting their useful lifespan. Ultra-fast boriding (UFB) surface treatment of carbon steel may drastically increase its corrosion resistance thereby providing a cost-effective material solution in geothermal applications. Scientists at Argonne National Laboratory (ANL) recently developed a technique to accelerate the boriding process using a high-temperature electrochemical process to produce relatively thick boride layers on various metal and alloy materials in minutes rather than the several hours it takes through the typical pack boriding process; hence, the process is designated UFB. The process uses molten borax salt at 900– 1000°C in an electrochemical cell in which the material to be borided is the cathode and a graphite plate is the anode. Continuous and durable boride layers with thicknesses of 100–300 µm have been produced on a variety of metals and alloys in one hour. Such a surface layer can indeed be a cost-effective pathway to prevent corrosion of casing materials in contact with the chemically aggressive and corrosive geothermal brine fluids.

15 GEOTHERMAL ENERGY↗
DOE OSTI2022

Facile Electrodeposition and Aging to Generate 3-Dimensional α-MnO 2 Battery Cathodes

Conventional tape casting forms 2-dimensional (2D) electrodes containing active material, conductive additive, and binder with restricted ion access as electrodes increase in thickness. To improve the transport properties, 3D architectures were developed using electrodeposition to ensure contact between the active material with the substrate, and provide enhanced electrolyte access. This paper investigates electrodeposition of cryptomelane ( α -MnO 2 ) as a model cathode material to efficiently accommodate (de)lithation and increase areal capacity vs conventional 2D coatings. Electodeposited samples on titantium (Ti) foil substrates were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) and show a linear increase of the average oxidation of Mn (3.5–3.8) and active mass loading (1.27–9.9 mg) with deposition and aging times (0–120 min). The initial deposition is amorphous and forms the crystalline material during the elevated temperature aging step. The active material, α -MnO 2 , was also deposited on C-cloth and these cathodes at deposition times of 3, 6, and 9 min deliver 9, 36, and 69% higher areal capacities, respectively, at 0.2 mA cm −2 compared to conventional 2D electrodes with a mass loading equal to the 3 min sample. These results demonstrate the benefit of α -MnO 2 within a porous architecture providing enhanced transport properties.

Electrochemistry↗
DOE OSTI2022

Stable Anode–Free All–Solid–State Lithium Battery through Tuned Metal Wetting on the Copper Current Collector

A stable anode-free all-solid-state battery (AF-ASSB) with sulfide-based solid-electrolyte (SE) (argyrodite Li 6 PS 5 Cl) is achieved by tuning wetting of lithium metal on “empty” copper current-collector. Lithiophilic 1 µm Li 2 Te is synthesized by exposing the collector to tellurium vapor, followed by in situ Li activation during the first charge. The Li 2 Te significantly reduces the electrodeposition/electrodissolution overpotentials and improves Coulombic efficiency (CE). During continuous electrodeposition experiments using half-cells (1 mA cm –2 ), the accumulated thickness of electrodeposited Li on Li 2 Te–Cu is more than 70 µm, which is the thickness of the Li foil counter-electrode. Full AF-ASSB with NMC811 cathode delivers an initial CE of 83% at 0.2C, with a cycling CE above 99%. Additionally, cryogenic focused ion beam (Cryo-FIB) sectioning demonstrates uniform electrodeposited metal microstructure, with no signs of voids or dendrites at the collector-SE interface. Electrodissolution is uniform and complete, with Li 2 Te remaining structurally stable and adherent. By contrast, an unmodified Cu current-collector promotes inhomogeneous Li electrodeposition/electrodissolution, electrochemically inactive “dead metal,” dendrites that extend into SE, and thick non-uniform solid electrolyte interphase (SEI) interspersed with pores. Density functional theory (DFT) and mesoscale calculations provide complementary insight regarding nucleation-growth behavior. Unlike conventional liquid-electrolyte metal batteries, the role of current collector/support lithiophilicity has not been explored for emerging AF-ASSBs.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Characterizing x-ray transmission through filters used in high energy density physics diagnostics

We report on the design and implementation of a new system used to characterize the energy-dependent x-ray transmission curve, Θ(E), through filters used in high-energy density physics diagnostics. Using an Amptek X-123-CdTe x-ray spectrometer together with a partially depleted silicon surface barrier detector, both the energy spectrum and total emission of an x-ray source have been accurately measured. By coupling these detectors with a custom PROTO-XRD x-ray source with interchangeable cathodes, accurate characterizations of Θ(E) for filters of varying materials and thicknesses have been obtained. The validity of the technique has been confirmed by accurately reproducing areal densities for high-purity filters with known x-ray transmission properties. In this paper, the experimental setup is described and the results of absorption calibrations performed on a variety of different filters are presented.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

The Shape Factor for Pits and Its Impact on Pit Stability

This study employs the finite element method (FEM) to predict the impact of pit shape on pit stability via shape factors of various pit geometries relevant to localized corrosion. Lower values of the shape factor indicate an increased ease in maintaining pit stability. Analyzed geometries include undercut pits, bispherical pit-within-pit structures, and covered pits with perforated (lacy) covers. The effect of the water layer thickness, transport properties of the electrolyte inside and outside the pit, and cathode location on the pit shape factor were also explored. Results show that occluded pits exhibit lower shape factors than open ones, with disk-shaped pits decreasing further as c/r ratio and occlusion angle increase. The findings also suggest minimal influence from a secondary pit if the primary remains active. An equation is presented that quantifies the impact of lacy covers, revealing significant shape factor value reduction. Additionally, high salt concentrations inside pits have a limited stabilizing effect compared to geometry, while thin water layers and adjacent cathodic/sinks reduce pit stability.

Shehi, A. (ORCID:0009000271548041)↗
DOE OSTI2021

Characterizing x-ray transmission through filters used in high energy density physics diagnostics

We report on the design and implementation of a new system used to characterize the energy-dependent x-ray transmission curve, Θ(E), through filters used in high-energy density physics diagnostics. Using an Amptek X-123-CdTe x-ray spectrometer together with a partially depleted silicon surface barrier detector, both the energy spectrum and total emission of an x-ray source have been accurately measured. By coupling these detectors with a custom PROTO-XRD x-ray source with interchangeable cathodes, accurate characterizations of Θ(E) for filters of varying materials and thicknesses have been obtained. The validity of the technique has been confirmed by accurately reproducing areal densities for high-purity filters with known x-ray transmission properties. In this paper, the experimental setup is described and the results of absorption calibrations performed on a variety of different filters are presented.

Pearcy, J.↗
DOE OSTI2020

Degradation & Performance Studies of ALD-Stabilized Nano-Composite SOFC Cathodes

This work showed, definitively, for the first time, that zirconia Atomic Layer Deposited (ALD) overcoats improve the stability of Solid Oxide Fuel Cell (SOFC) cathodes by chemically gettering interfacial Sr that has segregated out of lanthanum strontium cobalt iron oxide (LSCF). The optimum ALD ZrO 2 overcoat thickness was found to be ≥5 nm and <10 nm. Gadolinium doped ceria (GDC) pre-infiltration was also shown, for the first time, to improve SOFC cathode stability through the chemical getting of Sr at the LSCF-backbone and LSCF-gas interfaces. Due to the fact that it can be performed easily in air on large-area electrodes, GDC pre-infiltration is likely more commercially viable than ALD ZrO 2 overcoating as an interfacial Sr gettering technique. Combining ZrO 2 overcoating with GDC pre-infiltration was not successful because the GDC nano-particles gettered the ZrO 2 overcoat instead of the interfacial Sr.

30 DIRECT ENERGY CONVERSION↗
DOE OSTI2022

Effect of crystallite geometries on electrochemical performance of porous intercalation electrodes by multiscale operando investigation

Lithium-ion batteries are yet to realize their full promise because of challenges in the design and construction of electrode architectures that allow for their entire interior volumes to be reversibly accessible for ion storage. Electrodes constructed from the same material and with the same specifications, which differ only in terms of dimensions and geometries of the constituent particles, can show surprising differences in polarization, stress accumulation and capacity fade. Here, using operando synchrotron X-ray diffraction and energy dispersive X-ray diffraction (EDXRD), we probe the mechanistic origins of the remarkable particle geometry-dependent modification of lithiation-induced phase transformations in V2O5 as a model phase-transforming cathode. A pronounced modulation of phase coexistence regimes is observed as a function of particle geometry. Specifically, a metastable phase is stabilized for nanometre-sized spherical V2O5 particles, to circumvent the formation of large misfit strains. Spatially resolved EDXRD measurements demonstrate that particle geometries strongly modify the tortuosity of the porous cathode architecture. Greater ion-transport limitations in electrode architectures comprising micrometre-sized platelets result in considerable lithiation heterogeneities across the thickness of the electrode. These insights establish particle geometry-dependent modification of metastable phase regimes and electrode tortuosity as key design principles for realizing the promise of intercalation cathodes. Designing electrode architectures for Li-ion batteries that can be reversibly accessible for ion storage can be challenging. Using operando techniques the mechanistic origin of lithiation-induced phase transformations in a V2O5 model cathode is now clarified.

Luo, Yuting↗