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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 505 records · Page 28
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Pt–Co truncated octahedral nanocrystals: a class of highly active and durable catalysts toward oxygen reduction

We report a facile and scalable synthesis of Pt–Co truncated octahedral nanocrystals (TONs) by employing Pt(acac) 2 and Co(acac) 2 as precursors, together with CO molecules and Mn atoms derived from the decomposition of Mn 2 (CO) 10 as a reductant and a {111} facet-directing agent, respectively. Both the composition and yield of the Pt–Co TONs could be varied through the introduction of CHCl 3 . When tested at 80 °C using membrane electrode assembly (MEA), the 4 nm Pt 2.6 Co TONs gave a mass activity of 294 A g Pt –1 at beginning-of-life (BOL) and it increased to 384 A g Pt –1 during recovery cycles. The mass activity at BOL only dropped by 24% after 30 000 voltage cycles at end-of-life (EOL) in a metal dissolution accelerated stress test. The Pt 2.6 Co/C catalyst outperformed the commercial TKK Pt 3 Co/C (230 A g Pt –1 at BOL and 40% loss after 30 000 cycles at EOL) in terms of both activity and durability. Our systematic analysis suggested that the enhancement in activity can be attributed to the combination of small, uniform size and well-defined {111} facets. This new class of catalysts holds promise for applications in proton-exchange membrane fuel cells.

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

High-Temperature Reference Electrode for Chloride Salts

The unique properties of molten salts enable their use in a wide range of applications, including metal electrodeposition, electrorefining, and as electrolytes in high-temperature batteries. Moreover, molten salts will be used as a coolant in molten salt reactors and as working media in pyrorocessing for nuclear energy applications. As a result, predicting the behavior and properties of the elements involved in the technological processes that employ molten salts is important. The activity of chloride ions in chloride molten salts has a large influence on the behavior of the salts in these applications and one of the key components in measuring the chloride activity is a stable reference electrode. This project aims to develop a reliable and convenient method for measuring chloride ion activity over a wide range of temperatures and salt compositions in chloride salt mixtures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Durable Thin‐Film Porous Transport Electrodes for High Current Density PEM Water Electrolysis

Proton exchange membrane water electrolyzers rely on relatively expensive Ir-based catalysts for efficient and durable hydrogen production. To reduce system costs, Ir loadings can be reduced if performance and durability are maintained. Sputter deposition is a readily scalable method to synthesize uniform, low-loading catalyst layers with controlled composition. A catalyst applied directly to the porous transport layer can have advantages for performance, manufacturing simplicity, and catalyst recovery. Suitable porous transport layer porosity can minimize activity losses when reducing loadings. Here, methods are presented to deposit metallic Ir as well as amorphous and rutile Ir oxides. The activity and durability of these materials in the porous transport electrode architecture is evaluated. The metallic and amorphous forms have better initial activity, however, operation at 3 A cm −2 with 0.1 mg Ir cm −2 shows that only rutile IrO 2 maintains performance beyond 100 h with a 50 mV improvement after 700 h. A >10x reduced dissolution rate is shown for rutile IrO 2 . With a low-porosity transport layer and 0.4 mg Ir cm −2 , a steady-state voltage decay rate of 6 µV h −1 is achieved. The results demonstrate that sputter-deposited rutile IrO 2 porous transport electrodes with low Ir loading can be operated at high current density to reduce hydrogen production costs.

08 HYDROGEN↗
DOE OSTI2022

(La 0.8 Sr 0.2 ) 0.98 MnO 3-δ -Zr 0.92 Y 0.16 O 2-δ :PrOx for oxygen electrode supported solid oxide cells

(La 0.8 Sr 0.2 ) 0.98 MnO 3-δ (LSM)- Zr 0.92 Y 0.16 O 2-δ (YSZ) has been widely studied as the cathode for solid oxide fuel cells (SOFCs), but its low activity has been a cell performance limiting factor. Herein, LSM-YSZ:PrO x composite is developed as an active electrocatalyst for both oxygen reduction and evolution reactions. A single step PrO x infiltration into LSM-YSZ lowers the polarization resistance (Rp) 10–20 times depending on the test temperature. Distribution of relaxation times (DRT) calculation reveals that adding PrO x affects surface exchange between adsorbed/desorbed oxygen and lattice oxygen, and oxygen dissociative adsorption/desorption. A symmetrical cell with a thin YSZ electrolyte sandwiched between thick LSM-YSZ:PrO x electrode-supports is developed and its oxygen generation performance and stability are evaluated under various current densities and temperatures. Finally, reversible solid oxide cell (ReSOC) performance is also reported for LSM-YSZ:PrO x supported cells with the oxide fuel electrode Sr 0.95 (Ti 0.3 Fe 0.63 Ni 0.07 )O 3-δ (STFN).

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

Effect of growth dynamics on the structural, photophysical and pseudocapacitance properties of famatinite copper antimony sulphide colloidal nanostructures (including nanosheets)

Facile phase selective synthesis of copper antimony sulphide (CAS) nanostructures is important because of their tunable photoconductive and electrochemical properties. In this study, off-stoichiometric famatinite phase CAS (fCAS) quasi-spherical and quasi-hexagonal colloidal nanostructures (including nanosheets) of sizes, 2.4–18.0 nm were grown under variable conditions of temperature (60–200 °C), time and oleylamine capping ligand concentration using copper(II) acetylacetonate and antimony(III) diethyldithiocarbamate precursors. Data from powder X-ray diffraction, Raman spectroscopy and high-resolution scanning/transmission electron microscopy confirm the tetragonal structure of the famatinite phase. X-ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscopy-energy dispersive X-ray spectroscopy data suggest a correlation of particle size, morphology and composition of the off-stoichiometric fCAS nanostructures with growth temperature and time, and oleylamine concentration. The off-stoichiometric Cu 3-a Sb 1+b S 4±c (a, b, c – mole fractions) nanostructures being severely copper-deficient and antimony-rich, exhibit shallow-lying acceptor copper vacancy states, deep-lying donor states of antimony interstitials, sulphur vacancies and antimony-copper antisites and shallow-lying acceptor surface trapping states. Further, these electronic states are likely implicated in tunable UV-visible absorption and bandgaps between 2.3 and 2.8 eV, and broad visible-NIR photoluminescence with fast recombination of radiative lifetimes between 0.2 and 6.2 ns, confirmed from absorption, steady-state and time-resolved photoluminescence spectroscopies. Additionally, cyclic voltammetry and electrochemical impedance spectroscopy confirm that electrodes of the fCAS nanostructures display slightly variable pseudocapacitance of charge-storage primarily via possible sodium ion intercalation with a high specific capacitance of ~84 F g -1 obtained at a scan rate of 5 mV s -1 . Overall, these results show the influence of composition, in particular point defects, phase quality and morphology on the optical and pseudocapacitance properties of fCAS nanostructures, suitable as solar absorbers or electrodes for energy storage devices.

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

Electrical-Discharge-Machining Contamination Removal from Metal Additively Manufactured Components

The use of an electrochemical dissolution process is shown to remove the recast layer contamination from the surfaces of electrical-discharge-machining cut components, as well as the interior exposed surfaces of the structure. The solution chemistry, cell potential, and exposure time are all relevant interdependent variables. Optimization of the electrode geometry should be made for each type of component. For the case of Cu-Zn recast contamination of 300-series alloy components, surface composition analysis indicates that complete electrochemical dissolution is achieved using a dilute solution of nitric acid (HNO 3 ). For example, electrochemical dissolution of the Cu-Zn recast is accomplished at 1.2 V cell potential using a 20% nitric solution and an exposure time of 4 h. The use of a nitric acid bath was specifically chosen since it’s chemically compatible and will not degrade the host alloy or the component. In sum, an electrochemically driven dissolution process can be tailored to remove of the recast contamination without affecting the integrity of the host component structure and its dimensional tolerances.

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

Nucleation-promoting and growth-limiting synthesis of disordered rock-salt Li-ion cathode materials

Disordered rock-salt oxides and oxyfluorides are promising positive electrode materials for high-performance lithium-ion batteries free of nickel and cobalt. However, conventional synthesis methods rely on post-synthesis pulverization to achieve cycling-appropriate particle sizes, offering limited control over particle microstructure and crystallinity. This accelerates degradation and complicates secondary particle processing. Here we present a synthesis strategy that enhances nucleation while suppressing particle growth and agglomeration across various disordered rock-salt compositions, including lithium–manganese–titanium oxide, lithium–manganese–niobium oxide, and lithium–nickel–titanium oxide systems. Applied to Li 1.2 Mn 0.4 Ti 0.4 O 2 , this method yields highly crystalline, well-dispersed sub-200 nm particles that form homogeneous electrode films with stable cycling behavior. Tested in cells with lithium metal as the counter electrode, these electrodes deliver ~200 mAh/g with 85% capacity retention relative to the first cycle after 100 cycles (20 mA/g, 1.5–4.8 V), and an average discharge voltage loss of 4.8 mV per cycle, compared to 38.6% retention and 7.5 mV loss per cycle for electrodes derived from pulverized solid-state particles. This approach suggests a route to enhance the performance and durability of disordered rock-salt electrodes for sustainable lithium-ion batteries.

Batteries↗
DOE OSTI2023

Super p-sulfur cathodes for quasi-solid-state lithium-sulfur-batteries

Lithium-Sulfur (Li-S) batteries have become a promising candidate to meet the current energy storage demand, with its natural abundance of materials, high theoretical capacity of 1672 mAhg-1, high energy density of 2600 Whkg-1, low cost and lower environmental impact. Sulfide based solid state electrolytes (SSEs) have received greater attention due to their higher ionic conductivity, compatible interface with sulfur-based cathodes, and lower grain boundary resistance. However, the interface between SSEs and cathodes has become a challenge in all solid-state Li-S batteries due to the rigidity of the participating surfaces. A hybrid electrolyte containing SSE coupled with a small amount of ionic liquid, was essential to improve the interface contact of the SSE with the electrodes. Coating-based cathodes were successfully fabricated using water-based carboxymethyl cellulose (CMC) solution and Styrene butadiene rubber (SBR) as the binder with low sulfur loading (0.70 mgcm-2) as well as high sulfur loading (4.0 mgcm-2). Solid-state composite powder-based cathodes pressed onto SSE (loading 4.0 mgcm-2) with enhanced electronic and ionic conductivity were fabricated with Super P: Sulfur (SP:S) and SSE. Ionic Liquids (IL) prepared using Lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) as salt, with premixed pyrrolidinium bis(trifluoromethyl sulfonyl)imide (PYR) as solvent and 1,3-dioxolane (DOL) as diluent were used to wet both SSE-electrode interfaces. The effect of IL dilution, co-solvent amount, LiTFSI concentration, C rate at which the batteries are tested and the effect of SSE inside the cathode, were systematically studied and optimized to develop a quasi-solid-state electrolyte Li-S battery (QSSLSB) with higher capacity retention and cyclability. LiTFSI (2M) dissolved in PYR:DOL(1:1) found to be optimum IL combination for low sulfur loading QSSLSBs reaching 500 mAh/g after 100 cycles while LiTFSI (3M) in PYR:DOL(1:3) was the optimum IL concentration for higher loading QSSLSBs reaching 400 mAh/g after 100 cycles. This work reports promising results of QSSLSB based on novel Li6PS5F0.5Cl0.5 Li-argyrodite solid-state electrolyte (SSE) with minute amount of IL, Super P-Sulfur (SP:S) cathode, and Li-anode. It also offers a new insight into the intimate interfacial contacts between the SSE and carbon-sulfur cathodes, which will be critical for improved electrochemical performance of quasi-solid-state lithium-sulfur batteries with high sulfur loading in the future.

25 ENERGY STORAGE↗
DOE OSTI2025

Thermochemical measurements of FeCl 2 in LiCl via electromotive force, coulometric titration, and cyclic voltammetry

The thermochemical properties of FeCl 2 in the LiCl-FeCl 2 binary system were determined at 913 K using electromotive force (emf) cells containing pre-made and coulometrically titrated molten salt compositions. Coulometric titration to in-situ change the salt composition utilizes the multiple valences of Fe ions and the tendency of Fe 3+ ions to comproportionate with Fe metal, forming additional Fe 2+ . The emf results were used to define the compositions in which Henry’s law is applicable, up to approximately 2 mol% FeCl 2 . Thermochemical quantities were determined from emf using a Standard Lithium Chloride Electrode (SLiCE) which defines 0 V as the reduction of Li + in pure LiCl at all temperatures. Validation of emf measurements was performed by comparing the formal potential measured by using cyclic voltammetry (2.224 ± 0.013 V vs SLiCE) and emf measurements (2.236 ± 0.004 V). In conclusion, this work shows that coulometric titration of an electroactive species that undergoes comproportionation can be used to rapidly obtain granular emf data in molten salt systems.

Coulometric titration↗
DOE OSTI2025

Indium Tin-Doped Oxide Interactions with Solvent Radiolysis Products

Transparent conductive oxides (TCOs), such as indium tin-doped oxide (ITO), are ubiquitous as components of electronics and are ideal electrode substrates for catalysis, energy transformation reactions, and energy storage applications. Recently, researchers have recognized their effectiveness as electrode materials for manipulating actinide oxidation states in solution. Despite their popularity as electrode materials, prior studies focused extensively on the direct radiolysis of TCO materials in air and rarely examined these effects within a solution, limiting our fundamental understanding of the interactions between solvent radiolysis products and these substrates in high radiation environments. Here, in this study, we characterize the effects of solvent radiolysis products—arising from the gamma irradiation of water, aqueous nitric acid solutions, and n-dodecane—on the composition, surface speciation, and band structure of ITO thin films on a glass substrate as a function of absorbed dose using UV-visible spectroscopy, scanning electron microscopy, photoelectrochemistry, and X-ray photoelectron spectroscopy. Our work demonstrates that mesoporous thin film electrodes of ITO exposed to gamma radiation in each solvent accumulate defects and exhibit solvent and dose dependent changes to their surface and interfacial properties. These electrodes maintain their electrochemical function and improve their photoelectrochemical performance up to at least 100 kGy of accumulated gamma dose, confirming their utility in solvents exposed to ionizing radiation fields.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Lithiophilic CoF 2 @C hollow spheres towards spatial lithium deposition for stable lithium metal batteries

Lithium metal (LM) is a promising anode for next-generation batteries due to its high theoretical capacity and low electrode potential. Nonetheless, side reactions, volume change, and unwanted lithium dendrite growth seriously limit the practical application of LM. Herein, with the aid of a hard template approach, a novel lithiophilic CoF 2 -carbon hollow sphere (CoF 2 @C-HS) composite material is successfully prepared via a facile in-situ fluorination and etching strategy. The lithiophilic CoF 2 acts as nucleation sites to reduce nucleation overpotential as well as induces the spatial Li deposition and the formation of LiF-rich solid electrolyte interphase (SEI), and the hollow carbon matrix can enhance the electrical conductivity and offer free space for LM deposition. Theoretical simulations reveal that the synergistic effect of lithiophilic CoF 2 and hollow carbon matrix homogenizes the electric field distribution and Li + flux. Benefiting from these advantages, the CoF 2 @C-HS-modified copper substrate electrode delivers an enhanced Coulombic efficiency (CE) of 93.7% for 280 cycles at 1 mA cm –2 and 1 mA h cm –2 . The symmetrical cell using CoF 2 @C-HS can stably cycle more than 1800 h with a low voltage hysteresis of 11 mV at a current density of 0.5 mA cm –2 and an areal capacity of 0.5 mA h cm –2 . Moreover, the Li@CoF 2 @C-HS composite anode enables more than 300 stable cycles at 1 C with a capacity retention of 95% in LiFePO 4 -based full cell and 110 stable cycles at 1 C in LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)-based high-voltage full cell. Finally, this work might shed a new light on designing lithiophilic hosts to spatially confine LM deposition, realizing dendrite-free LM anodes and the practical applications of LM batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

Composite interlayer for lithium metal based solid state batteries and the method of making the same

A solid-state electrochemical cell that cycles lithium ions includes a solid-state electrolyte that defines a first major surface and an electrode that defines a second major surface. The solid-state electrochemical cell also includes an interfacial layer disposed between the first major surface of the solid-state electrolyte and the second major surface of the electrode. The interfacial layer may include an ion-conductor disposed in an organic matrix.

Chen, Mengyuan↗
DOE OSTI2021

Recent advances in integrating platinum group metal-free catalysts in proton exchange membrane fuel cells

Platinum group metal (PGM)-free catalysts are promising low-cost materials for the oxygen reduction reaction in proton exchange membrane fuel cells (PEMFCs). A variety of chemical precursors and synthesis methods have been proposed to increase their catalytic activity. In comparison, significantly less attention has been dedicated to the integration of these PGM-free catalysts into operating electrodes by investigating the role of the membrane electrode assembly (MEA) fabrication on the PEMFC performance. Here, we discuss here some remarkable performance improvements recently achieved by tuning catalyst loading, ionomer content, and ink solvent composition, and call for further explorations of the ink processing and MEA fabrication to improve performance.

25 ENERGY STORAGE↗
DOE OSTI2024

Durability enhancement of all-solid-state electrochromic devices by adjusting the charge density ratio between electrochromic and counter electrode layers

Here, owing to an increase in global warming, smart-window devices based on charge-balanced electrochromic devices (ECDs), which exhibit high potential to increase the thermal efficiency of buildings, have gained prominence. However, studies on the fabrication and cycling stability of charge-balanced ECDs are scarce. In this study, WO 3 and NiO x films were deposited on indium-tin-oxide (ITO)-coated glass substrates by reactive direct-current magnetron sputtering, and the deposition time was varied to control the thickness and charge density of the thin films. Subsequently, the NiO x /ITO/glass and WO 3 /ITO/glass substrates were laminated with a Li-based polymeric electrolyte to fabricate all-solid-state ECDs comprising electrochromic (EC) and counter-electrode (CE) layers in charge-density ratios of 12.6, 6.4, 2.3, and 1.1. Changes in the electrochromic properties, device-layer microstructure, crystal structure, and elemental composition of the as-constructed ECDs before and after degradation were investigated to understand the influence of the charge-density ratio of the EC and CE layers on the long-term durability of ECDs. Increasing the charge-density ratio decreased the cycling stability of the device owing to changes in the microstructure and crystal structure of the NiO x layer in the microstructural deep-trap sites. Among all the ECDs, those comprising EC and CE layers with similar charge densities showed the most stable optical modulation and highest long-term durability. Finally, based on the aforementioned results, a degradation mechanism for charge-imbalanced all-solid-state ECDs was proposed. This study is expected to open new frontiers in designing optimal-performance electrochemical devices with a wide variety of potential applications.

14 SOLAR ENERGY↗
DOE OSTI2025

Resistive Switching of Spinel Li 4 Ti 5 O 12 Lithium-Ion Battery Material for Neuromorphic Computing

The rapid rise of AI has exposed significant limitations in conventional Von Neumann computing architecture, particularly in regard to speed and energy efficiency. To address these challenges, researchers are exploring a brain-inspired neuromorphic architecture that mimics biological neural networks, enabling massive parallel processing with reduced power consumption for complex AI computational demands. Recent interest has focused on utilizing battery electrodes and solid electrolyte materials for their resistive switching properties in developing a neuromorphic architecture. These properties are precisely tuned through local- and bulk-level chemical composition modifications via voltage bias stimuli. In this study, we demonstrate fabricating a three-terminal lithium-ion electrochemical transistor based on lithium titanium oxide (Li 4 Ti 5 O 12 ), a popular lithium-ion battery anode material. We deposited and characterized LTO thin films using RF sputtering, demonstrating a 6 orders of magnitude increase in electronic conductivity upon lithiation, with conductivity plateauing after 20% lithiation. Density functional theory calculations revealed transformation from the insulating to conducting state, supported by experimental characterization through X-Ray Photoelectron Spectroscopy (XPS) and Direct Current (DC) polarization analyses. The fabricated transistor consisted of LTO as the channel layer, gold as source/drain terminals, lithium phosphorus oxynitride (LiPON) as the lithium-ion conductor, and copper as the gate terminal. The device exhibited clear hysteresis in transfer characteristics due to lithium insertion/extraction processes. Long-term potentiation (LTP) and long-term depression (LTD) measurements showed an asymmetric ratio of 1.425 and maximum/minimum conductance ratio of 7.83. When implemented in a deep neural network (DNN) for MNIST handwritten digit recognition, the device achieved 92.03% accuracy over 20 training epochs. Detailed transport mechanism analysis revealed the crucial role of oxygen vacancies and interface effects in device operation. Our preliminary findings establish LTO-based lithium-ion electrochemical transistors as promising candidates for energy-efficient neuromorphic computing applications, offering potential solutions to traditional Von Neumann architecture limitations.

25 ENERGY STORAGE↗
DOE OSTI2020

The early-stage growth and reversibility of Li electrodeposition in Br-rich electrolytes

Significance Spatial variations in chemical composition and transport properties of the material phases (interphases) formed on reactive metals in liquid electrolytes are thought to be responsible for the propensity of metal battery electrodes to electrodeposit in irregular, nonplanar morphologies. Equilibrium theoretical calculations using joint density functional analysis in vacuum and generic liquid media indicate that in-plane transport at such interphases is enhanced substantially if LiX (X = Br > Cl > F) species predominate. This study employs optical visualization experiments and nucleation theory to experimentally investigate nucleation and early-stage growth dynamics of metallic lithium in electrolytes enriched with LiBr. It is shown that the Li-Br–rich interphases formed profoundly alter the morphology of Li electrodeposits by enhancing Li-ion surface diffusion.

25 ENERGY STORAGE↗
DOE OSTI2020

In Operando XANES Imaging of High Capacity Intermetallic Anodes for Lithium Ion Batteries

In operando 2D X-ray absorption near edge structure (XANES) imaging was performed near the Cu K-edge during cycling of Cu 6 Sn 5 composite anodes for lithium ion batteries. Galvanostatic lithiation and delithiation with intermittent constant voltage holds near reaction plateaus show evolution of absorption spectra for active material particles. XANES spectra obtained from images taken during cycling were compared to standard spectra for Cu, Cu 6 Sn 5 , and Li 2 CuSn. Chemical composition was assessed for Cu-containing phases. Distinct Cu, Cu 6 Sn 5 , and Li 2 CuSn regions were identified for each voltage plateau. Mechanical degradation, electrode particle fracture and expansion were observed during delithiation. Furthermore, movement of particles during cycling suggests that expansion also impacts the supporting secondary phases and the transport networks therein. These results demonstrate that spectroscopic X-ray imaging methods can clearly distinguish chemically distinct phases in alloy electrodes and have the versatility to observe the evolution of these phases during lithiation and delithiation.

25 ENERGY STORAGE↗