SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Na(AuO2)2 crystallizes in the tetragonal P4_2/mmc space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Na–O bond lengths are 2.60 Å. Au+3.50+ is bonded in a square co-planar geometry to four equivalent O2- atoms. All Au–O bond lengths are 2.02 Å. O2- is bonded in a see-saw-like geometry to two equivalent Na1+ and two equivalent Au+3.50+ atoms.
Na(RuO2)4 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. Na1+ is bonded in a body-centered cubic geometry to eight equivalent O2- atoms. All Na–O bond lengths are 2.82 Å. Ru+3.75+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing RuO6 octahedra. The corner-sharing octahedral tilt angles are 53°. There are a spread of Ru–O bond distances ranging from 1.95–2.07 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to two equivalent Na1+ and three equivalent Ru+3.75+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to three equivalent Ru+3.75+ atoms.
Na(WO3)3 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Na1+ is bonded to twelve O2- atoms to form NaO12 cuboctahedra that share corners with six equivalent NaO12 cuboctahedra and faces with eight WO6 octahedra. There are six shorter (2.74 Å) and six longer (2.75 Å) Na–O bond lengths. There are two inequivalent W+5.67+ sites. In the first W+5.67+ site, W+5.67+ is bonded to six equivalent O2- atoms to form WO6 octahedra that share corners with six equivalent WO6 octahedra and faces with two equivalent NaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 2°. All W–O bond lengths are 1.95 Å. In the second W+5.67+ site, W+5.67+ is bonded to six O2- atoms to form WO6 octahedra that share corners with six WO6 octahedra and faces with three equivalent NaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. There is three shorter (1.93 Å) and three longer (1.96 Å) W–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+ and two W+5.67+ atoms. In the second O2- site, O2- is bonded in a distorted square co-planar geometry to two equivalent Na1+ and two equivalent W+5.67+ atoms.
Na(Nb3Se4)2 crystallizes in the trigonal P-3 space group. The structure is three-dimensional. Na1+ is bonded in a distorted hexagonal planar geometry to six equivalent Se2- atoms. All Na–Se bond lengths are 3.28 Å. Nb+2.50+ is bonded to six Se2- atoms to form a mixture of distorted face, edge, and corner-sharing NbSe6 octahedra. The corner-sharing octahedra tilt angles range from 45–55°. There are a spread of Nb–Se bond distances ranging from 2.61–2.82 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to six equivalent Nb+2.50+ atoms to form distorted face-sharing SeNb6 pentagonal pyramids. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to one Na1+ and four equivalent Nb+2.50+ atoms.
Na(V3S4)2 crystallizes in the trigonal P-3 space group. The structure is three-dimensional. Na1+ is bonded in a distorted hexagonal planar geometry to six equivalent S2- atoms. All Na–S bond lengths are 3.03 Å. V+2.50+ is bonded to six S2- atoms to form a mixture of corner, edge, and face-sharing VS6 octahedra. The corner-sharing octahedra tilt angles range from 44–55°. There are a spread of V–S bond distances ranging from 2.33–2.58 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to one Na1+ and four equivalent V+2.50+ atoms. In the second S2- site, S2- is bonded to six equivalent V+2.50+ atoms to form distorted face-sharing SV6 pentagonal pyramids.
Na(Ti3Se4)2 crystallizes in the trigonal P-3 space group. The structure is three-dimensional. Na1+ is bonded in a distorted hexagonal planar geometry to six equivalent Se2- atoms. All Na–Se bond lengths are 3.31 Å. Ti+2.50+ is bonded to six Se2- atoms to form a mixture of edge, corner, and face-sharing TiSe6 octahedra. The corner-sharing octahedra tilt angles range from 42–53°. There are a spread of Ti–Se bond distances ranging from 2.56–2.67 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to one Na1+ and four equivalent Ti+2.50+ atoms. In the second Se2- site, Se2- is bonded to six equivalent Ti+2.50+ atoms to form distorted face-sharing SeTi6 pentagonal pyramids.
Na(CoO2)3 is Ilmenite-like structured and crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are four shorter (2.45 Å) and two longer (2.47 Å) Na–O bond lengths. There are two inequivalent Co+3.67+ sites. In the first Co+3.67+ site, Co+3.67+ is bonded to six O2- atoms to form edge-sharing CoO6 octahedra. There is four shorter (1.89 Å) and two longer (1.90 Å) Co–O bond length. In the second Co+3.67+ site, Co+3.67+ is bonded to six O2- atoms to form edge-sharing CoO6 octahedra. All Co–O bond lengths are 1.88 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to one Na1+ and three Co+3.67+ atoms to form a mixture of distorted edge and corner-sharing ONaCo3 trigonal pyramids. In the second O2- site, O2- is bonded to one Na1+ and three Co+3.67+ atoms to form a mixture of distorted edge and corner-sharing ONaCo3 trigonal pyramids.
Accurate knowledge of the total mass of molten salts both for pyroprocessing spent nuclear fuels and for molten salt reactors is necessary for safeguards purposes. However, it is challenging to know or measure the total mass of molten salt due to the complicated shapes as well as the compositional—and thus density—changes that occur over time during operation. Here, we investigated radioactive tracer dilution (RTD) as a potential safeguards technique for application to the total mass measurement of LiCl–KCl–UCl 3 salt used for uranium electrorefining, with a focus on the feasibility, uncertainty, and fission product effect of RTD for salt mass measurement. To this end, experimental-scale RTD tests (600–700 g of total mass) were initially carried out by adding 22 Na tracer salt into LiCl–KCl salt containing 0, 5, and 28wt% radioactive salts from an electrorefiner (ER) for refining uranium. Upon the completion of the experimental-scale RTD tests, we performed a scale-up RTD test by directly adding 22 Na tracer salts to the ER, which uses about 12 kg of LiCl–KCl–UCl 3 salt during normal operation. This paper reports the main features of RTD for total mass measurement of molten salt and summarizes the results of the experimental-scale and scale-up RTD tests.
Desalination of brackish water sources is critical to addressing the growing global freshwater demand. One promising approach is electrically driven desalination using intercalation electrodes. While intercalation electrodes have been widely researched for energy storage applications, only a small subset of those materials is suitable for desalination. In this work, we report the synthesis, characterization, and in-device testing of three Prussian blue analogue intercalation compounds: copper, manganese, and zinc hexacyanoferrate with formulas K x M[Fe(CN) 6 ] z ·nH 2 O (M = Cu, Mn, Zn). The desalination performance for each of these materials against carbon electrodes is reported for Na + intercalation and for Ca 2+ intercalation using 1000 ppm NaCl and 1000 ppm CaCl 2 feed solutions, respectively. While the copper and manganese analogs showed promising performance for Na + and Ca 2+ intercalation, the zinc compound was unstable and underwent rapid dissolution. Manganese hexacyanoferrate showed the best desalination performance in terms of salt removal capacities and salt removal rates with NaCl while copper hexacyanoferrate performed the best with CaCl 2 . The manganese analog proved to be the most stable intercalation material, retaining 83% and 72% of its salt removal capacity after 280 cycles in NaCl and CaCl 2 feed solutions respectively.
Tailoring molecular structures of organic electrode materials (OEMs) can enhance their performance in Na-ion batteries, however, the substitution rules and the consequent effect on the specific capacity and working potential remain elusive. Herein, by examining three sodium carboxylates with selective N substitution or extended conjugation structure, we exploited the correlation between structure and performance to establish substitution rules for high-capacity OEMs. Our results show that substitution position and types of functional groups are essential to create active centers for uptake/removal of Na+ and thermodynamically stabilize organic structures. Furthermore, rational host design and electrolytes modulation were performed to extend the cycle life to 500 cycles. A full cell based on the optimal 2,2’-bipyridine-4,4’-dicarboxylic acid disodium salt anode and the polyaniline cathode is demonstrated to confirm the feasibility of achieving all-organic batteries. Lastly, this work provides a valuable guideline for the design principle of high-capacity and stable OEMs for sustainable energy storage.
Na + -gated nanochannel membranes were synthesized on α-Al 2 O 3 supports by secondary growth for ammonia (NH 3 ) separation from a mixture gas containing NH 3 , hydrogen (H 2 ) and nitrogen (N 2 ) at high temperature and pressure. Here, the effects of synthesis parameters (number of seeding steps, aging time, synthesis time, and Si/Al ratio) on membrane properties were investigated by characterization and gas permeation testing. Under the optimized condition (two-time seeding, 8 h aging time, 5 h synthesis time, and gel composition of 1.05 Al 2 O 3 : 5 SiO 2 : 50 Na 2 O: 100 H 2 O), the best membranes achieved NH 3 /H 2 and NH 3 /N 2 selectivities of 328 ± 60 and 1106 ± 207, respectively at 200 °C and 21 bar. Separation performance of the membrane was shown to be highly dependent on the permeances of N 2 and H 2 , which were greatly influenced by the membrane quality.
Due to flexible structure tunability and abundant structure diversity, redox-active polymers are promising cathode materials for developing affordable and sustainable Na-ion batteries (NIBs). However, polymer cathodes still suffer from low capacity, poor cycle life, and sluggish reaction kinetics. Herein, we designed and synthesized a polymer cathode material bearing carbonyl and azo groups as well as extended conjugation structures in the repeating units. The polymer cathode exhibited exceptional electrochemical performance in NIBs in terms of high capacity, long lifetime, and fast kinetics. When coupled with a low-concentration electrolyte, it shows superior performance at low temperatures down to -50 °C, demonstrating great promise for low-temperature battery applications. Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) were employed to study the reaction mechanism, interphase structure, and morphological evolution, confirming reversible redox reactions between azo/carbonyl groups in the polymer and Na + /electrons, a NaF-rich interphase, and high structure stability upon cycling. In conclusion, this work provides an effective approach to developing high-performance polymer cathodes for affordable, sustainable, and low-temperature NIBs.
Na is alpha Po structured and crystallizes in the cubic Pm-3m space group. The structure is zero-dimensional and consists of one sodium molecule. Na is bonded in a 1-coordinate geometry to atoms.
Abstract The layered sodium transition metal oxide, NaTMO 2 (TM = transition metal), with a binary or ternary phases has displayed outstanding electrochemical performance as a new class of strategy cathode materials for sodium‐ion batteries (SIBs). Herein, an in‐depth phase analysis of developed Na 1− x TMO 2 cathode materials, Na 0.76 Ni 0.20 Fe 0.40 Mn 0.40 O 2 with P2‐ and O3‐type phases (NFMO‐P2/O3) is offered. Structural visualization on an atomic scale is also provided and the following findings are unveiled: i) the existence of a mixed‐phase intergrowth layer distribution and unequal distribution of P2 and O3 phases along two different crystal plane indices and ii) a complete reversible charge/discharge process for the initial two cycles that displays a simple phase transformation, which is unprecedented. Moreover, first‐principles calculations support the evidence of the formation of a binary NFMO‐P2/O3 compound, over the proposed hypothetical monophasic structures (O3, P3, O′3, and P2 phases). As a result, the synergetic effect of the simultaneous existence of P‐ and O‐type phases with their unique structures allows an extraordinary level of capacity retention in a wide range of voltage (1.5–4.5 V). It is believed that the insightful understanding of the proposed materials can introduce new perspectives for the development of high‐voltage cathode materials for SIBs.
Vanadyl phosphates comprise a class of multielectron cathode materials capable of cycling two Li + , about 1.66 Na + , and some K + ions per redox center. In this review, structures, thermodynamic stabilities, and ion diffusion kinetics of various A x VOPO 4 (A = Li, Na, K, NH 4 ) polymorphs are discussed. Both the experimental data and first-principle calculations indicate kinetic limitations for alkali metal ions cycling, especially between for 0 ≤ x ≤ 1, and metastability of phases with x > 1. This creates challenges for multiple-ion cycling, as the slow kinetics call for nanosized particles, which being metastable and reactive with organic electrolytes are prone to side reactions. Thus, various synthesis approaches, surface coating, and transition metal ion substitution strategies are discussed here as possible ways to stabilize A x VOPO 4 structures and improve alkali metal ion diffusion. Finally, the role of advanced characterization techniques, such as X-ray absorption spectroscopy, diffraction, pair distribution function analysis and 7 Li and 31 P NMR, in understanding the reaction mechanism from both structural and electronic points of view is emphasized.
Abstract Activation of oxygen redox represents a promising strategy to enhance the energy density of positive electrode materials in both lithium and sodium‐ion batteries. However, the large voltage hysteresis associated with oxidation of oxygen anions during the first charge represents a significant challenge. Here, P3‐type Na 0.67 Li 0.2 Mn 0.8 O 2 is reinvestigated and a ribbon superlattice is identified for the first time in P3‐type materials. The ribbon superstructure is maintained over cycling with very minor unit cell volume changes in the bulk while Li ions migrate reversibly between the transition metal and Na layers at the atomic scale. In addition, a range of spectroscopic techniques reveal that a strongly hybridized Mn 3d–O 2p favors ligand‐to‐metal charge transfer, also described as a reductive coupling mechanism, to stabilize reversible oxygen redox. By preparing materials under three different synthetic conditions, the degree of ordering between Li and Mn is varied. The sample with the maximum cation ordering delivers the largest capacity regardless of the voltage windows applied. These findings highlight the importance of cationic ordering in the transition metal layers, which can be tuned by synthetic control to enhance anionic redox and hence energy density in rechargeable batteries.
Sodium layered oxides Na x MO 2 (x ≤ 1 and M = transition metal ions) have gained significant interest as sodium-ion battery (NIB) cathodes owing to their high operating voltages and potential for higher energy density compared with polyanion and Prussian blue–type cathodes. However, their practical applications are often hindered by the irreversible structural transitions leading to capacity fading during cycling. The nature and substitution of transition metal ions define the material properties and electrochemical performance. In this study, through comprehensive electrochemical characterization combined with multi-scale structural and spectroscopical analyses, we demonstrate the synergistic impacts of Lithium and Titanium doping, which not only increases overall capacity by boosting cation and anion cooperative redox contributions but also improves the rate capability and cycling stability. Specifically, Li + doping enhances the available sodium inventory for extraction, while Ti 4+ disrupts Na + /vacancy ordering at lower voltages (< 4 V) and mitigates the detrimental P2→OP4/O2 phase transition during cycling. The combined effect of Lithium and Titanium doping promotes more charge localization on Oxygen, which activates reversible lattice oxygen redox reactions at elevated voltages, contributing additional capacity beyond conventional cationic redox. This work provides crucial insights into the design of high-performance, high-capacity P2-type layered cathode materials for sodium-ion batteries.
Sodium‐ion batteries (SIBs) are one of the most promising next‐generation energy storage systems because of their abundant and low‐cost component materials. However, the lower energy density of SIBs compared with lithium‐ion batteries diminishes their practical value proposition. Among the many sodium‐based cathodes, layered transition metal oxides with high sodium content have energy densities comparable with the lithium‐ion battery technology. When charged above 4.1 V, the sodium‐based cathodes often undergo transformations because the activation of oxygen anion redox causes irreversible oxygen release, transition metal ion migration, lattice distortion, and rapid capacity decay. Here, in situ gas analysis is performed to evaluate the lattice oxygen anion redox activity in Na x Ni y Mn 1− y O 2 cathodes with P2 and O3 structural orderings. Operando X‐ray diffraction and neutron diffraction are performed to assess the structural changes related to lattice oxygen redox and transition metal ion migration in Na x Ni y Mn 1− y O 2 cathodes. The results unveil that in‐plane honeycomb cationic ordering can help suppress oxygen anion redox activity, which is critical for the future design of layered transition metal oxide cathodes that are prone to achieve high‐energy for durable SIBs.