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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Directing High-Efficiency Na Plating with Carbon–Aluminum Junction Interfaces for Anode-Free Na Metal Batteries

Anode-free sodium metal batteries are highly promising for future energy storage but suffer from much faster cycling degradation as they are sensitive to even trace levels of irreversible side reactions. This work focuses on the most practical Al foil current collectors and systematically examined the effect of nano-sized carbon coating on improving the Na plating and stripping stability. We identified that the carbon-Al junction interface generated by carbon coating enabled more uniform Na depositing with lower overpotentials, delivering higher than 99.8% Faradaic efficiencies for a wide range of cycling currents between 0.5 and 3.0 mA cm -2 . This performance is much better than the 96.4% efficiency observed on uncoated Al foils under the same conditions, and was also confirmed under lean electrolyte and freezing electrolyte conditions, and can be attributed to the stronger interfacial binding and enhanced sodiophilic properties of the carbon-aluminum junction sites. Furthermore, these sites not only ensure uniform Na plating but also eliminates side reactions that would otherwise cause electrolyte depletion. As a result, Na-metal free full cells assembled with high capacity Na 3 V 2 (PO 4 ) 3 cathode delivered ~ 85% capacity retention for 100 cycles, higher than the 73% of retention of uncoated Al foil.

25 ENERGY STORAGE↗
DOE OSTI2024

Demystifying In Situ Pyrolysis Chemistry for High-Performance Polyanionic Cathodes in Sodium-Ion Batteries

In this article, the carbon coating strategy has emerged as an indispensable approach to improve the conductivity of polyanionic cathodes. However, owing to the complex reaction process between precursors of carbon and cathode, establishing a unified screening principle for carbonaceous precursors remains a technical challenge. Herein, we reveal that carbonaceous precursor pyrolysis chemistry undeniably influences the formation process and performance of Na 3 V 2 (PO 4 ) 3 (NVP) cathodes from in situ insights. By investigating three types of carbonaceous precursors, it is found that O/H-containing functional groups can provide more bonding sites for cathode precursors and generate a reducing atmosphere by pyrolysis, which is beneficial to the formation of polyanionic materials and a uniform carbon coating layer. Conversely, excessive pyrolysis of functional groups leads to a significant amount of gas, which is detrimental to the compactness of the carbon layer. Furthermore, the substantial presence of residual heteroatoms diminishes graphitization. In this case, it is demonstrated that carbon dots (CDs) precursors with suitable functional groups can comprehensively enhance the Na+ migration rate, reversibility, and interface stability of the cathode material. As a result, the NVP/CDs cathode displays outstanding capacity retention, maintaining 92% after 10,000 cycles at a high rate of 50 C. Altogether, these findings provide a valuable benchmark for carbon source selection for polyanionic cathodes.

25 ENERGY STORAGE↗
DOE OSTI2022

Electrodes and lithium ion cells with high capacity anode materials

High capacity silicon based anode active materials are described for lithium ion batteries. These materials are shown to be effective in combination with high capacity lithium rich cathode active materials. Supplemental lithium is shown to improve the cycling performance and reduce irreversible capacity loss for at least certain silicon based active materials. In particular silicon based active materials can be formed in composites with electrically conductive coatings, such as pyrolytic carbon coatings or metal coatings, and composites can also be formed with other electrically conductive carbon components, such as carbon nanofibers and carbon nanoparticles. Additional alloys with silicon are explored.

Lopez, Herman A.↗
DOE OSTI2022

Synthesis of high-density olivine LiFePO 4 from paleozoic siderite FeCO 3 and its electrochemical performance in lithium batteries

The lithium-ion cathode material olivine LiFePO 4 (LFP) has been synthesized for the first time from natural paleozoic iron carbonate (FeCO 3 ). The ferrous carbonate starting material consists of the mineral siderite at about 92 wt. % purity. Because FeCO 3 has divalent iron, the reaction with lithium dihydrogen phosphate (LiH 2 PO 4 ) provides a unique method to develop iron-(II) containing LFP in an inert atmosphere. Since siderite FeCO 3 is a common mineral that can be directly mined, it may, therefore, provide an inexpensive route for the production of LFP. After carbon-coating, the LFP yields a capacity in the range of 80–110 mAh g -1 LFP (in one chosen specimen sample), which is lower than commercially available LiFePO 4 (150–160 mAh g -1 LFP ). However, the tap density of LFP derived from siderite is noticeably high at 1.65 g cm -3 . The material is likely to be improved with powder purification, nanosized processing, and more complete carbon-coating coverage with increased optimization.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Learning heterogeneous reaction kinetics from X-ray videos pixel by pixel

Reaction rates at spatially heterogeneous, unstable interfaces are notoriously difficult to quantify, yet are essential in engineering many chemical systems, such as batteries and electrocatalysts. Experimental characterizations of such materials by operando microscopy produce rich image datasets, but data-driven methods to learn physics from these images are still lacking because of the complex coupling of reaction kinetics, surface chemistry and phase separation. Here we show that heterogeneous reaction kinetics can be learned from in situ scanning transmission X-ray microscopy (STXM) images of carbon-coated lithium iron phosphate (LFP) nanoparticles. Combining a large dataset of STXM images with a thermodynamically consistent electrochemical phase-field model, partial differential equation (PDE)-constrained optimization and uncertainty quantification, we extract the free-energy landscape and reaction kinetics and verify their consistency with theoretical models. We also simultaneously learn the spatial heterogeneity of the reaction rate, which closely matches the carbon-coating thickness profiles obtained through Auger electron microscopy (AEM). Across 180,000 image pixels, the mean discrepancy with the learned model is remarkably small (<7%) and comparable with experimental noise. Our results open the possibility of learning nonequilibrium material properties beyond the reach of traditional experimental methods and offer a new non-destructive technique for characterizing and optimizing heterogeneous reactive surfaces.

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

Learning heterogeneous reaction kinetics from X-ray movies pixel-by-pixel

Reaction rates at spatially heterogeneous, unstable interfaces are notoriously difficult to quantify, yet are essential in engineering many chemical systems, such as batteries 1 and electrocatalysts 2. Experimental characterizations of such materials by operando microscopy produce rich image datasets 3–6, but data-driven methods to learn physics from these images are still lacking because of the complex coupling of reaction kinetics, surface chemistry and phase separation 7. Here we show that heterogeneous reaction kinetics can be learned from in situ scanning transmission X-ray microscopy (STXM) images of carbon-coated lithium iron phosphate (LFP) nanoparticles. Combining a large dataset of STXM images with a thermodynamically consistent electrochemical phase-field model, partial differential equation (PDE)-constrained optimization and uncertainty quantification, we extract the free-energy landscape and reaction kinetics and verify their consistency with theoretical models. We also simultaneously learn the spatial heterogeneity of the reaction rate, which closely matches the carbon-coating thickness profiles obtained through Auger electron microscopy (AEM). Across 180,000 image pixels, the mean discrepancy with the learned model is remarkably small (<7%) and comparable with experimental noise. Our results open the possibility of learning nonequilibrium material properties beyond the reach of traditional experimental methods and offer a new non-destructive technique for characterizing and optimizing heterogeneous reactive surfaces.

Chueh, William↗
DOE OSTI2024

CRADA Number NFE-21-08827 with DayLyte, Inc. (CRADA Final Report)

DayLyte Batteries is developing an aqueous Sodium-Air battery made with abundant materials while being half to a third the weight of Li-ion to power electric aircraft, electric vehicles and provide renewable energy on demand. To make this battery practical, DayLyte is developing a thin film ceramic Nasicon solid electrolyte amenable to rapid scaleup as well as a protective coating that will protect the solid electrolyte from 50wt% NaOH during the battery’s end-of-discharge while still allowing Na-ions to pass back and forth. If the thin film solid electrolyte and stable coating can be developed it will open the world to step change in battery performance all while not sacrificing the environment on the way. The project was designed to first focus on making and characterizing the Nasicon membrane followed by measuring its electrochemical performance, then assembling a full cell, optimizing its NaOH stability and then optimize the overall prototype design. Over the past two years, we have significantly improved the Nasicon film uniformity, demonstrated protective ligands that are stable in 50wt% NaOH by measuring no mass change with a quartz crystal microbalance, tested different heating methods like tube furnace and rapid heating and developed glassy carbon coatings on the current collector to prevent Nasicon-current collector alloying. We have found that getting film uniformity as measured by electrochemical impedance spectroscopy (EIS) is difficult because of different factors like surface roughness, deposition uniformity and heat treatment time and uniformity. The glassy carbon coating should significantly reduce the surface roughness and by tuning the coating conditions the film deposition uniformity improves and using an automated heating method should lead to much improved film uniformity.

25 ENERGY STORAGE↗
DOE OSTI2024

Modification of CO2/H2O Selectivity of Polymer Through Graphene Coating for Carbon Capture Materials

A harmful issue that needs attention and solution is the rising carbon dioxide (CO2) in our atmosphere. Carbon dioxide in our atmosphere is at an all time high and has continuously increased since the industrial revolution. It has increased tremendously going from 315 parts per million (ppm) in the 1960s up to 419.3 ppm in 2023 as shown in Figure 1. Moreover, CO2 emissions have increased from 11 billion tons/year in the 1960s to 38.6 billion tons/year in 2023. The increase in CO2 found in our atmosphere has a number of detrimental effects such as increase in global temperatures and an increase in the ocean’s acidity. Human activities are greatly involved in the cause of CO2 emissions. At Lawrence Livermore National Lab (LLNL) the Microencapsulated CO2 sorbents (MECS) division has been doing research and investigating formulations for their microcapsules. MECS are core-shell microcapsules consisted of a highly permeable polymer shell and a fluid (sodium carbonate solution) that reacts and absorbs carbon dioxide. An example of the microcapsules are shown in Figure 2. Equation 1 shows the chemical reaction of the fluid (sodium carbonate) contained in the polymer shell that acts as the carbon dioxide sorbent and becomes sodium bicarbonate. The LLNL MECS team is in the process of scaling up their microcapsules for potential applications in “carbon capture from flue gas streams generated by fossil fuel combustion in industrial plants and operations, carbon capture in breweries and soft drink manufacture, carbon capture directly from indoor air to improve its quality”. The microcapsule’s possibility for commercial applications was discovered in 2017.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Superlubricity coating containing carbon nanotubes

A method for producing a structure containing an array of MWCNTs on a metal substrate, comprising: (i) subjecting a metal substrate to a surface oxidation process at a first elevated temperature in an oxygen-containing atmosphere and under a first reduced pressure; (ii) subjecting the metal substrate to a surface reduction process at a second elevated temperature in a reducing atmosphere and under a second reduced pressure of at least 0.01 atm and less than 1 atm to result in reduction of the surface of said metal substrate, wherein the reducing atmosphere contains hydrogen gas; (iii) subjecting the metal substrate to a third reduced pressure of no more than 0.1 atm; and (iv) contacting the metal substrate, while at the third reduced pressure and under an inert or reducing atmosphere, with an organic substance at a third elevated temperature for suitable time to produce the MWCNTs on the metal substrate.

Ihala Gamaralalage, Chanaka Kapila↗
DOE OSTI2024

Annealed metal nano-particle decorated nanotubes

Disclosed are methods and systems of providing carbon nanotubes decorated with polymer coated metal nanoparticles. Then, annealing the metal coated carbon nanotubes to reduce a quantity of hydrophilic components of the polymer coating.

Iftime, Gabriel↗
DOE OSTI2021

Functionalized carbon nanotubes for thermionic emission and cooling applications

Barium strontium oxide-coated carbon nanotubes (CNTs) were implemented as a work function lowering and field enhancing functional coating on a coiled tungsten filament to create a new thermionic cathode. This cathode resembles conventional oxide cathodes in structure. It has the same coiled tungsten filament as a conventional oxide cathode but uses barium strontium oxide-coated CNTs instead of the traditional barium strontium calcium oxide powder mixture as an emissive coating. The cathode produces a strong thermionic emission. At 1395 K and 2.5 V/μm, the thermionic emission current of 0.87 A or current density of 2.9 A/cm 2 was obtained from this oxide-coated CNT cathode. This level of emission is about three times as large as a conventional oxide cathode operating at similar temperature and field strength. Strong thermionic emissions from the cathode also lead to a large thermionic cooling effect. Temperature reduction as large as 90° was observed from the cathode surface when it was emitting electrons. Strong thermionic emission and a large cooling effect obtained are the result of the combination of the low work function of barium strontium oxide (1.6 eV) and the large field effect induced by the CNTs. Plasma enhanced chemical vapor deposition was used to grow CNTs, and magnetron sputtering deposition was used to deposit the barium strontium oxide functional coating; details of the cathode fabrication are presented to illustrate both the versatility of the processing techniques and the adaptability of barium strontium oxide-coated CNTs as a functional coating. Finally, measurements on thermionic emission and thermionic cooling of the cathode are also presented.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Quantification of the carbon bonding state in amorphous carbon materials: A comparison between EELS and NEXAFS measurements

In this report the quantitative determination of the carbon hybridization is critical for establishing processing-structure-properties relationships for carbon-based materials, including amorphous carbon coatings. While several techniques have been employed to characterize the amount of sp 2 and sp 3 carbon in these materials, direct comparisons between analytical results are limited. Here, we compare near edge X-ray absorption fine structure (NEXAFS) spectra of a silicon- and oxygen-containing hydrogenated amorphous carbon (a-C:H:Si:O) coating acquired in synchrotron-based scanning transmission X-ray microscopy (STXM) mode with electron energy loss spectra (EELS) obtained from the same a-C:H:Si:O lamella. While the fractions of sp 2 carbon computed from STXM and EELS spectra are in close agreement, the comparison of NEXAFS spectra acquired in STXM mode with NEXAFS spectra collected in partial electron yield mode on a flat a-C:H:Si:O surface indicated that the destructive preparation of thin lamellae for STXM analyses induces variations in the structure of a-C:H:Si:O, namely the breakage of carbon-silicon and carbon-hydrogen bonds, a change in ordering of sp 2 -bonded carbon, and an increase in the sp 2 carbon fraction. These findings can help scientists in the careful interpretation of spectroscopic results obtained from the analysis of samples made of metastable materials after the destructive preparation of specimens for analytical purposes.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Dispersion of modified fumed silica in elastomeric nanocomposites

In polymer nanocomposites, surface modification of silica aggregates can shield Coulombic interactions that inhibit agglomeration and formation of a network of agglomerates. Surface modification is usually achieved with silane coupling agents although carbon-coating during pyrolytic silica production is also possible. Pyrogenic silica with varying surface carbon contents were dispersed in styrene-butadiene (SBR) rubber to explore the impact on hierarchical dispersion, the emergence of meso-scale structures, and the rheological response. Pristine pyrogenic silica aggregates at concentrations above a critical value (related to the Debye screening length) display correlated meso-scale structures and poor filler network formation in rubber nanocomposites due to the presence of silanol groups on the surface. Here, in the present study, flame synthesized silica with sufficient surface carbon monolayers can mitigate the charge repulsion thereby impacting network structural emergence. The impact of the surface carbon on the van der Waals enthalpic attraction, a * , is determined. The van der Waals model for polymer nanocomposites is drawn through an analogy between thermal energy, k B T, and the accumulated strain, γ. The rheological response of the emergent meso-scale structures depends on the surface density of both carbon and silanol groups.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Nanostructured C@CuS Core–Shell Framework with High Lithium-Ion Storage Performance

In this study, we have synthesized a nanostructured core–shell framework of carbon-coated copper sulfide (C@CuS) through a one-step precipitation technique. The carbon sphere template facilitated the nucleation of CuS nanostructures. The synthesized nanocomposites have demonstrated remarkable lithium-ion storage capabilities when utilized as an anode in lithium-ion batteries. Notably, they exhibit an impressive rate capability of 314 mAh g -1 at a high current density of 5000 mA g -1 , along with excellent long-term cycle stability, maintaining 463 mAh g -1 at 1000 mA g -1 after 800 cycles. This superior performance is due to the core–shell architecture of the composite, where the carbon core enhances the conductivity of CuS nanoparticles and mitigates volume expansion, thus preventing capacity loss. Our study not only elucidates the significance of carbon in the construction of nano-heterojunctions or composite electrodes but also presents a practical approach to significantly boost the electrochemical performance of CuS and other metal sulfides.

25 ENERGY STORAGE↗
DOE OSTI2020

Temperature-dependent Battery Performance of a Na 3 V 2 (PO 4 ) 2 F 3 @MWCNT Cathode and In-situ Heat Generation on Cycling

Excellent structural stability, high operating voltage, and high capacity have made Na 3 V 2 (PO 4 ) 2 F 3 a promising cathode material for sodium-ion batteries. However, high-temperature battery performances and heat generation measurements have not been systematically reported yet. Carbon-coated Na 3 V 2 (PO 4 ) 2 F 3 @MWCNT (multi-walled carbon nanotube) samples are fabricated by a hydrothermal-assisted sol-gel method and the electrochemical performances are evaluated at three different temperatures (25, 45, and 55 °C). Furthermore, the well-crystallized Na 3 V 2 (PO 4 ) 2 F 3 @MWCNT samples exhibit good cycling stability at both low and high temperatures; they deliver an initial discharge capacity of 120–125 mAhg -1 at a 1 C rate with a retention of 53 % capacity after 1,400 cycles with 99 % columbic efficiency. The half-cell delivers a capacity of 100 mAhg -1 even at a high rate of 10 C at room temperature. Furthermore, the Na 3 V 2 (PO 4 ) 2 F 3 @MWCNT samples show good long-term durability; the capacity loss is an average of 0.05 % per cycle at a 1 C rate at 55 °C. Additionally, ionic diffusivity and charge transfer resistance are evaluated as functions of state of charge, and they explain the high electrochemical performance of the Na 3 V 2 (PO 4 ) 2 F 3 @MWCNT samples. In-situ heat generation measurements reveal reversible results upon cycling owing to the high structural stability of the material. Excellent electrochemical performances are also demonstrated in the full-cell configuration with hard carbon as well as antimony Sb/C anodes.

25 ENERGY STORAGE↗