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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Multifunctional transitional metal-based phosphide nanoparticles towards improved polysulfide confinement and redox kinetics for highly stable lithium-sulfur batteries

The shuttle effect and the sluggish redox kinetics of lithium polysulfides (LiPSs) are the major issues impeding the practical applications of lithium-sulfur batteries (LSBs). Herein, a highly-efficient Ni 2 P electrocatalyst supported on N, P co-doped graphene (Ni 2 P@NPG) is developed via a simple “recrystallization-self-assembly” method to address the above issues. Here, the ultrafine Ni 2 P nanoparticles ensure abundant adsorption-diffusion-conversion interfaces for accelerating LiPSs transformation and Li 2 S deposition, which extremely decreases the accumulation of LiPSs in the electrolyte and therefore prevents the migration of LiPSs. Their superior catalytic performance is demonstrated by reduced Gibbs free energy changes of rate-limiting step based on the systematic theoretical calculations and the reduced shuttle effect is tested by the three-dimensional reconstructions of Raman depth profiles. Benefiting from these synergistic effects, the LSBs with Ni 2 P@NPG modified separators present a superior cycling performance with an average capacity decay rate of 0.048 % per cycle at 1C around the 400 cycles and a high-rate capacity of 731 mAh/g at 2C. Even with a high-sulfur loading of 3.53 mg cm –2 , the cell can still contain a reversible capacity of 809 mAh/g at 0.2C with a remarkable columbic efficiency of 98.4 %.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Exploring the potential and impact of single-crystal active materials on dry-processed electrodes for high-performance lithium-ion batteries

Roll-to-roll powder-to-film dry processing (DP) and single-crystal (SC) active materials (AMs) with many advantages are two hot topics of lithium-ion batteries (LIBs). However, DP of SC AMs for LIBs is rarely reported. Consequently, the impact of SC AMs on dry-processed LIBs is not well understood. Herein, for the first time, via a set of experimental and theoretical studies of the conventional polycrystalline-AM- and SC-AM-based DPed electrodes (DPEs), this work not only reports a high-performance dry SC-AM cathode for LIB manufacturing, but also establishes some fundamental understanding of SC-based dry-processed electrodes, including their morphology, structure, mechanical strength, electronic conductivity and LIB electrochemical behavior. Further, the results suggest that DP of SC AMs is promising, which can dramatically improve the electrochemical kinetics at electrode level and particle level. Specifically, for the rate capability and long-term cyclability in full cells, SC DPEs exhibit a discharge specific capacity of 152.1 mAh g -1 at 1C and a capacity retention rate of 79.9 % at C/3 over 500 cycles, which are superior to those of PC DPEs (135.6 mAh g -1 and 68.3 %) at the same conditions and are further confirmed by the simulation data from the theoretical modelling study. Therefore, this comprehensive work marks a significant milestone for DP strategy and SC AMs, enlightening future research and development of LIB manufacturing.

25 ENERGY STORAGE↗
DOE OSTI2025

Rate Limiting Regimes in Photochemical H2 Generation by Complexes of Colloidal CdS Nanorods and Hydrogenase

Driving redox enzyme catalysis with photoexcited semiconductor nanocrystals is a compelling approach for chemical conversion. We examined how the interplay of the many chemical steps involved determines the rates of photochemical H2 production with complexes of colloidal CdS nanorods and an [FeFe]-hydrogenase. We elucidated the roles of three critical and previously elusive processes-scavenging of photoexcited holes from nanorods, back-electron transfer, and H2 oxidation. Kinetic Monte Carlo simulations and fitting to experimental data revealed that hole transfer becomes the rate-limiting step at high illumination intensities. Comparisons of simulations to experimental H2 production showed that both back-electron transfer and H2 oxidation play an efficiency-limiting role at high catalyst loadings. This work provides guiding principles for tuning experimental parameters to minimize energy-wasting pathways and optimize photochemical product formation. More broadly, we demonstrate how critical but elusive chemical steps in photochemical reactions can be probed with a combination of experiments and simulations.

08 HYDROGEN↗
DOE OSTI2025

A cradle-to-grave life-cycle-assessment of dry-processed Li-ion batteries for electric vehicles

Maxwell-type dry processing has emerged as a promising manufacturing technology for high-areal-loading Li-ion battery electrodes, offering a significant advantage by eliminating the use of the toxic and costly NMP solvent. This study developed a cradle-to-grave life-cycle-assessment model to evaluate the environmental impacts of this innovative technology, benchmarking the results against the conventional NMP-based technique for a configured 42 kWh NMC622-graphite battery pack. Furthermore, the findings reveal that the dry-processing method merits a 4.8% lower energy consumption and achieves environmental impacts up to 47.5% lower in 12 out of 13 categories, highlighting its environmental benefits compared with the NMP-based manufacturing processes.

Electrode↗
DOE OSTI2025

Influence of strain-rate on the response of elastomeric architected materials

Architected materials have shown substantial promise in impact mitigation and protective applications, and there has accordingly been great interest in better characterizing their response at elevated strain rates due to impact. There remains ambiguity regarding the contribution of inertial and material responses to strain rate sensitivity, and, in particular, when these effects begin to gain dominance in the impact response of an architected material. The response of soft polymer architected materials as a function of strain rate, in particular, has been little investigated. We characterize the experimental impact response of four soft polymer architected lattice geometries across varying strain rates in the intermediate strain rate regime (∼10 3 s −1 ) using split-Hopkinson pressure bar loading and high speed video characterization of the resulting deformation fields. In conclusion, our results highlight the interplay of influence between constituent material, lattice geometry, length scale, and strain rate in determining the onset of significant inertia effects.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Energy, economic, and environmental analysis of integration of thermal energy storage into district heating systems using waste heat from data centres

Data centres produce waste heat, which can be utilized in district heating systems. However, the mismatch between data centres’ heat supply and district heating systems’ heat demands limits its utilization. Further, high peak loads increase the operation cost of district heating systems. This study aimed to solve these problems by introducing thermal energy storages. A water tank and a borehole thermal energy storage system were selected as the short-term and long-term thermal energy storage, respectively. Energy, economic, and environmental indicators were introduced to evaluate different solutions. The case study was a campus district heating system in Norway. Results showed that the water tank could shave the peak load by 31% and save the annual energy cost by 5%. The payback period was lower than 15 years when the storage efficiency remained higher than 80%. However, it had no obvious benefits in terms of mismatch relieving and CO emissions reduction. In contrast, the borehole thermal energy storage increased the waste heat utilization rate to 96% and reduced the annual CO emissions by 8%. However, the payback period was more than 17 years. These results provide guidelines for the retrofit of district heating systems, where data centres’ waste heat is available.

25 ENERGY STORAGE↗
DOE OSTI2025

Pool boiling heat transfer evaluation of next-generation dielectric fluid: Opteon™ 2P50

The growing use of artificial intelligence has led to heavy thermal loads and high heat dissipation rates in data centers. Conventional air-cooled technologies are not able to fulfill these requirements. To overcome these challenges, two-phase immersion cooling (2PIC) has emerged as one of the leading technologies for high power-density chips. 2PIC increases the heat dissipation rate and efficiency of the system while reducing the footprint of the cooling equipment. A fluid with adequate dielectric properties, a suitable normal boiling temperature to maintain chip temperatures, and good material compatibility, is desired for 2PIC system. In this study, the pool boiling heat transfer of a new developmental dielectric fluid, Opteon™ 2P50, was experimentally investigated. The heat transfer coefficients at various heat fluxes (20–150 kW/m 2 ) and the critical heat flux were measured using a smooth aluminum surface. Compared with HFE-7100, Opteon™ 2P50 shows higher heat transfer coefficient (up to 59% higher) and a slightly lower value of critical heat flux (around 5.9% lower). The modified Cooper correlation with the optimized leading constant resulted in reliable prediction accuracy with a 5.3% mean absolute error percentage. Overall, these results indicate that the new dielectric fluid provides similar thermal performance to some legacy fluids.

2P50↗
DOE OSTI2022

Three-dimensional mapping of mineral in intact shark centra with energy dispersive x-ray diffraction

The centra of shark vertebrae consist of cartilage mineralized by a bioapatite similar to bone's carbonated hy-droxyapatite, and, without a repair mechanism analogous to remodeling in bone, these structures still survive millions of cycles of high-strain loading. The main structures of the centrum are an hourglass-shaped double cone and the intermedialia which supports the cones. Little is known about the nanostructure of shark centra, spe-cifically the relationship between bioapatite and cartilage fibers, and this study uses energy dispersive diffraction (EDD) with polychromatic synchrotron x-radiation to study the spatial organization of the mineral phase and its crystallographic texture. The unique energy-sensitive detector array at beamline 6-BM-B, the Advanced Photon Source, enables EDD to quantify the texture within each sampling volume with one exposure while constructing 3D maps via specimen translation across the sampling volume. Herein this study maps a centrum from two shark orders, a carcharhiniform and a lamniform, with different intermedialia structures. In the blue shark (Prionace glauca, Carcharhiniformes), the bioapatite's c-axes are oriented laterally within the centrum's cone walls but axially within the wide wedges of the intermedialia; the former is interpreted to resist lateral deformation, the latter to support axial loads. In the shortfin mako (Isurus oxyrinchus, Lamniformes), there is some tendency for c-axis variation with position, but the situation is unclear because one dimension of the sampling volume is consid-erably larger than the thickness and spacing of the intermedialia's radially-oriented lamellae. Because elastic modulus in collagen plus bioapatite mineralized tissues varies significantly with both volume fraction of bio-apatite and crystallographic texture, the present 3D EDD-derived maps should inform future 3D numerical models of shark centra under applied load.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Unraveling the impact of the degree of dry mixing on dry-processed lithium-ion battery electrodes

Dry processing of lithium-ion battery electrodes facilely realizes the powder-to-film manner, which is thus regarded as a highly promising strategy for lithium-ion battery manufacturing. However, a fundamental understanding of the impact of the involved dry mixing is still rarely reported. In this work, the degree of dry mixing is monitored by the dry mixing time, and a set of dry-processed electrodes with different degree of dry mixing is accordingly prepared and comprehensively studied. This work novelly reveals that the degree of dry mixing exhibits pronounced impact on the morphology, the homogeneity of electrode components and the degree of PTFE fiberization, which leads to difference in the mechanical strength and electrochemical performance of dry-processed electrodes. Accordingly, it is suggested that a moderate degree of dry mixing is preferred for high-performance dry-processed lithium-ion battery electrodes.

25 ENERGY STORAGE↗
DOE OSTI2023

A conformal heat-drying direct ink writing 3D printing for high-performance lithium-ion batteries

High areal capacity electrodes hold great potential for high-energy density lithium-ion batteries (LIBs), but their poor electrochemical kinetics limit their power density. Here, in this study, high areal capacity 3D-structured LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathodes (4.3 mAh cm -2 ) are prepared via 3D printing with a manner of direct ink writing. The electrodes had an enlarged electrode–electrolyte contact area, shortened diffusion pathway, and reduced intercalation-induced stress, thereby delivering enhanced rate capability and cyclability in LIBs, which is 143.6 mAh g -1 at 3C and a 60.2 % capacity retention over 800 cycles at 1C. Moreover, at electrode level, the 3D-NMC exhibits an energy and power densities of 313.1 Wh kg -1 and 657.9 W kg -1 , respectively. Furthermore, the theoretical calculation suggests that reducing the gap width will be highly beneficial to the energy and power densities. This work establishes a milestone in understanding the cycling effect on the electrode local structure, including the void area and the LiNi 0.8 Mn 0.1 Co 0.1 O 2 region, which confirms the effectiveness of 3D printing for electrode preparation.

25 ENERGY STORAGE↗
DOE OSTI2023

Polysulfide regulation by defect-modulated Ta 3 N 5- x electrocatalyst toward superior room-temperature sodium-sulfur batteries

Resolving low sulfur reaction activity and severe polysulfide dissolution remains challenging in metal-sulfur batteries. Motivated by a theoretical prediction, herein, we strategically propose nitrogen-vacancy tantalum nitride (Ta 3 N 5-x ) impregnated inside the interconnected nanopores of nitrogen-decorated carbon matrix as a new electrocatalyst for regulating sulfur redox reactions in room-temperature sodium-sulfur batteries. Through a pore-constriction mechanism, the nitrogen vacancies are controllably constructed during the nucleation of Ta 3 N 5-x . Further, the defect manipulation on the local environment enables well-regulated Ta 5d-orbital energy level, not only modulating band structure toward enhanced intrinsic conductivity of Ta-based materials, but also promoting polysulfide stabilization and achieving bifunctional catalytic capability toward completely reversible polysulfide conversion. Moreover, the interconnected continuous Ta 3 N 5-x -in-pore structure facilitates electron and sodium-ion transport and accommodates volume expansion of sulfur species while suppressing their shuttle behavior. Due to these attributes, the as-developed Ta 3 N 5-x -based electrode achieves superior rate capability of 730 mAh g -1 at 3.35 A g -1 , long-term cycling stability over 2000 cycles, and high areal capacity over 6 mAh cm -2 under high sulfur loading of 6.2mgcm -2 . This work not only presents a new sulfur electrocatalyst candidate for metal-sulfur batteries, but also sheds light on the controllable material design of defect structure in hopes of inspiring new ideas and directions for future research.

25 ENERGY STORAGE↗
DOE OSTI2023

A detailed genome-scale metabolic model of Clostridium thermocellum investigates sources of pyrophosphate for driving glycolysis

Lignocellulosic biomass is an abundant and renewable source of carbon for chemical manufacturing, yet it is cumbersome in conventional processes. A promising, and increasingly studied, candidate for lignocellulose bioprocessing is the thermophilic anaerobe Clostridium thermocellum given its potential to produce ethanol, organic acids, and hydrogen gas from lignocellulosic biomass under high substrate loading. Possessing an atypical glycolytic pathway which substitutes GTP or pyrophosphate (PP i ) for ATP in some steps, including in the energy-investment phase, identification, and manipulation of PP i sources are key to engineering its metabolism. Previous efforts to identify the primary pyrophosphate have been unsuccessful. Here, we explore pyrophosphate metabolism through reconstructing, updating, and analyzing a new genome-scale stoichiometric model for C. thermocellum, iCTH669. Hundreds of changes to the former GEM, iCBI655, including correcting cofactor usages, addressing charge and elemental balance, standardizing biomass composition, and incorporating the latest experimental evidence led to a MEMOTE score improvement to 94%. We found agreement of iCTH669 model predictions across all available fermentation and biomass yield datasets. The feasibility of hundreds of PP i synthesis routes, newly identified and previously proposed, were assessed through the lens of the iCTH669 model including biomass synthesis, tRNA synthesis, newly identified sources, and previously proposed PP i -generating cycles. In all cases, the metabolic cost of PP i synthesis is at best equivalent to investment of one ATP suggesting no direct energetic advantage for the cofactor substitution in C. thermocellum. Even though no unique source of PP i could be gleaned by the model, by combining with gene expression data two most likely scenarios emerge. First, previously investigated PP i sources likely account for most PP i production in wild-type strains. Second, alternate metabolic routes as encoded by iCTH669 can collectively maintain PP i levels even when previously investigated synthesis cycles are disrupted. Model iCTH669 is available at github.com/maranasgroup/iCTH669.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Simulations of radiatively cooled magnetic reconnection driven by pulsed power

Magnetic reconnection is an important process in astrophysical environments, as it reconfigures magnetic field topology and converts magnetic energy into thermal and kinetic energy. In extreme astrophysical systems, such as black hole coronae and pulsar magnetospheres, radiative cooling modifies the energy partition by radiating away internal energy, which can lead to the radiative collapse of the reconnection layer. In this paper, we perform two- and three-dimensional simulations to model the MARZ (Magnetic Reconnection on Z) experiments, which are designed to access cooling rates in the laboratory necessary to investigate reconnection in a previously unexplored radiatively cooled regime. These simulations are performed in GORGON, an Eulerian two-temperature resistive magnetohydrodynamic code, which models the experimental geometry comprising two exploding wire arrays driven by 20 MA of current on the Z machine (Sandia National Laboratories). Radiative losses are implemented using non-local thermodynamic equilibrium tables computed using the atomic code Spk, and we probe the effects of radiation transport by implementing both a local radiation loss model and P 1/3 multi-group radiation transport. The load produces highly collisional, super-Alfvénic (Alfvén Mach number M A ≈ 1.5), supersonic (Sonic Mach number M S ≈ 4–5) strongly driven plasma flows which generate an elongated reconnection layer (Aspect Ratio L/δ≈100 , Lundquist number S L ≈ 400). The reconnection layer undergoes radiative collapse when the radiative losses exceed the rates of ohmic and compressional heating (cooling rate/hydrodynamic transit rate = τ$^{–1}_{cool}$/τ$^{–1}_{H}$ ≈100); this generates a cold strongly compressed current sheet, leading to an accelerated reconnection rate, consistent with theoretical predictions. Lastly, the current sheet is also unstable to the plasmoid instability, but the magnetic islands are extinguished by strong radiative cooling before ejection from the layer.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2020

Electrochemical Salt Wasteform Development: A Review of Salt Treatment and Immobilization Options

Electrochemical reprocessing, also referred to as pyroprocessing, is a technique for recycling actinides from used nuclear fuel (UNF) to produce fuel for future reactors. Here, UNF is dissolved in a molten salt (e.g., LiCl-KCl eutectic) within an electrorefiner. After UNF dissolution, fission products are released into the electrolyte salt and converted to chlorides. This paper discusses wasteform options for processing the base electrolyte salt with the fission product salts as well as just the rare-earth fission products (as RECl 3 , REOCl, or REO x ) with the intent of finding optimal methods for reducing total waste salt volumes or partitioning the salt for alternate wasteform options. Furthermore, two of the more detailed partitioning options discussed herein include halide removal from the salt (dehalogenation), which accounts for more than half of the salt on a molar basis, and RE fission product removal for wasteforms with high-RE loadings. Wasteform properties are compared with emphasis on wasteform volume starting from a given amount of (1) total salt cations or (2) RE cations. Comparisons are also made of wasteform chemical durabilities, with the data available from like testing methods. A main conclusion from this work is the justification of subsequent salt processing after electrorefiner operations for achieving significant wasteform volume reduction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Pelletization with Spark Plasma Sintering and Characterization of Metal Iodides: An Assessment of Long-Term Radioiodine Immobilization Options

Four promising iodine “getter” materials (Ag, Cu, Bi, and Sn) for radioiodine capture were assessed in their pure metal-iodide (MI x ) pelletized forms to compare relative chemical durabilities. To study chemical durability, commercial MI x compounds of AgI, BiI 3 , BiOI, CuI, and SnI 4 were converted to dense monolithic pellets using spark plasma sintering. Semidynamic leach testing in the form of modified ASTM C1308 tests was then performed on the pellets in two different forms including unmounted (as-pressed) specimens (i.e., “U”) and epoxy-mounted specimens (i.e., “M”) with polished surfaces. The chemical durability results and sample characterizations showed that three of the five MI x compounds tested (i.e., AgI, CuI, and BiOI) displayed moderate to high leach resistances. Further, the remaining two MI x compounds (i.e., BiI 3 and SnI 4 ), which are both desirable iodine waste forms due to their high iodine loading capacities, readily decomposed during leach testing, indicated by crystallographic changes in the specimens as well as large amounts of iodine detected in the leachate solutions. The instabilities of BiI 3 and SnI 4 raise uncertainties for using the base metals/cations (i.e., Bi 0 /Bi 3+ and Sn 0 /Sn 4+ , respectively) as viable getters for radioiodine capture due to likely poor waste form chemical durabilities after capture and consolidation into waste forms.

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

Effect of Graft Molecular Weight and Density on the Mechanical Properties of Polystyrene-Grafted Cellulose Nanocrystal Films

In this work, polymer-grafted nanoparticle (PGN) films were prepared from polystyrene (PS) grafted to rodlike cellulose nanocrystals (MxG-CNC-g-PS) with a controllable grafting density (0.03–0.25 chains/nm 2 ) and molecular weight (5–60 kg/mol). These nanorod-based PGNs are solution- and melt-processible, permitting access to one-component composite films with high nanofiller loadings (with up to 55 wt %). The impact of both grafted polymer density and molecular weight on the mechanical properties of the films was investigated and related to the polymer brush conformation: concentrated polymer brush (CPB), semidilute polymer brush (SDPB), or CPB core with SDPB corona (CPB/SDPB). The rubbery regime storage modulus (above $T_g$) showed 2 orders of magnitude increase, maximizing at a low degree of polymerization (N) and low grafting density (σ). Fracture toughness was maximized in samples with the grafted polymer in the SDPB or CPD/SDPB (higher N and relatively low σ) regime and showed enhancement relative to PS of molecular weight similar to the graft. In line with prior computation predictions, optimizing for both rubbery modulus and fracture toughness in such nanorod-based PGN films requires the polymers in the SDPB regime and CNC loading levels (ca. 50–60 wt %) that are difficult to attain in more traditional two-component CNC composites.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Hydrocarboxylation of C=C Bonds in Polycyclooctene: Progress Toward Valorization of Waste Polyolefins

Upcycling of waste polyolefins into higher-value functional polymers through chemical functionalization is a promising strategy to recover value and minimize their environmental impact. We report the hydrocarboxylation of polycyclooctene as a model for accessing ethylene acrylic acid copolymers (EAA) from waste polyethylene. The effects of various process parameters on the hydrocarboxylation were investigated. The relationship between carboxylic acid concentration and material properties, including crystallinity, melting temperature, glass transition temperature, adhesive properties, and wettability, was studied in comparison to an unfunctionalized polyethylene. Among the catalysts evaluated, Co 2 (CO) 8 exhibited relatively slow kinetics toward the hydrocarboxylation and was not compatible with 2,6-di-tert-butyl hydroxytoluene, a common additive present in commercial polyolefins. PdCl 2 (PPh 3 ) 2 exhibited a higher reactivity toward the hydrocarboxylation, though polymer gelation was observed with extended reaction times or high catalyst loadings. Carboxylic acid incorporation into the polymer was readily controlled by varying the reaction time. Altogether, the resultant COOH-functionalized polyolefins possessed properties analogous to commercial EAA.

36 MATERIALS SCIENCE↗