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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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NASA NTRS2011

Use of Additives to Improve Performance of Methyl Butyrate-Based Lithium-Ion Electrolytes

This work addresses the need for robust rechargeable batteries that can operate well over a wide temperature range. To this end, a number of electrolyte formulations have been developed that incorporate the use of electrolyte additives to improve the high-temperature resilience, low-temperature power capability, and life characteristics of methyl butyrate-based electrolyte solutions. These electrolyte additives include mono-fluoroethylene carbonate (FEC), lithium oxalate, vinylene carbonate (VC), and lithium bis(oxalato)borate (LiBOB), which have been shown to result in improved high-temperature resilience of all carbonate-based electrolytes. Improved performance has been demonstrated of Li-ion cells with methyl butyrate-based electrolytes, including 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %); 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 2% FEC; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 4% FEC; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + lithium oxalate; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 2% VC; and 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 0.10M LiBOB. These electrolytes have been shown to improve performance in MCMB-LiNiCoO2 and graphite-LiNi1/3Co1/3Mn1/3O2 experimental Li-ion cells. A number of LiPF6-based mixed carbonate electrolyte formulations have been developed that contain ester co-solvents, which have been optimized for operation at low temperature, while still providing reasonable performance at high temperature. For example, a number of ester co-solvents were investigated, including methyl propionate (MP), ethyl propionate (EP), methyl butyrate (MB), ethyl butyrate (EB), propyl butyrate (PB), and butyl butyrate (BB) in multi-component electrolytes of the following composition: 1.0M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (20:60:20 v/v %) [where X = ester co-solvent]. ["Optimized Car bon ate and Ester-Based Li-Ion Electrolytes", NASA Tech Briefs, Vol. 32, No. 4 (April 2008), p. 56.] Focusing upon improved rate capability at low temperatures (i.e., 20 to 40 C), this approach was optimized further, resulting in the development of 1.20M LiPF6 in EC+EMC+MP (20:20:60 v/v %) and 1.20M LiPF6 in EC+EMC+EB (20:20:60 v/v %), which were demonstrated to operate well over a wide temperature range in MCMB-LiNiCoAlO2 and Li4Ti5O12(-)LiNiCoAlO2 prototype cells.

Smart, Marshall C.↗

NASA NTRS2017

Constraints on Mechanisms of Chondrule Formation from Chondrule Precursors and Chronology of Transient Heating Events in the Protoplanetary Disk

The mineralogy, petrography, and oxygen-isotope compositions of porphyritic chondrules—dominant chondrule type in most chondrite groups—suggest formation by incomplete melting of isotopically diverse precursors during localized transient heating events in dust-rich regions of the protoplanetary disk characterized by 16O-poor compositions (D17Odust+gas~ –7‰ to +4‰) relative to the inferred Sun’s value (D17O ~ –28 ± 2‰). The chondrule precursors included Ca,Al-rich inclusions (CAIs), amoeboid olivine aggregates (AOAs), chondrules of earlier generations, fine-grained matrix-like material, and possibly fragments of pre-existing planetesimals. Like porphyritic chondrules, igneous CAIs formed by melting of isotopically diverse precursors during transient heating events, but in an isotopically distinct, solar-like reservoir of the protoplanetary disk (D17O dust + gas ~ –24‰), probably near the proto Sun. Based on a narrow range of the initial 26Al/27Alratios inferred from the internal Al-Mg isochrons in igneous CAIs, their melting started at the very beginning of Solar System formation (t0), defined by the CV CAIs with U-corrected Pb-Pb age of 4567.3 ± 0.16 Ma and the canonical 26Al/27Al ratio of (5.25 ± 0.02) ¥ 10–5, and lasted at least 0.3 Ma. The U-corrected Pb-Pb absolute and 26Al-26Mg relative ages of porphyritic chondrules from type 3 ordinary, CO, CV, and CR carbonaceous chondrites (assuming uniform distribution of 26Al in the disk at the canonical level) suggest chondrule formation started at t0 and lasted for about 4 Ma. These observations may preclude formation of the majority of porphyritic chondrules by splashing of differentiated planetesimals and by collisions between planetesimals; instead, they are consistent with melting of dust balls by bow shocks or magnetized turbulence in the disk. Some porphyritic chondrules in equilibrated (petrologic type 4–6) ordinary chondrites contain relict fragments of coarse-grained chromite, ilmenite, phosphates, and albitic plagioclase. The similar mineral assemblage is commonly observed in type 4–6 ordinary chondrites, but is absent in type 3 chondrites, suggesting these chondrules formed by incomplete melting of thermally metamorphosed ordinary chondrite material, possibly by impacts. The CB metal-rich carbonaceous chondrites contain exclusively magnesian non-porphyritic chondrules crystallized from complete melts. These chondrules formed in a gas-melt plume generated by a hypervelocity (≥20 km/s) collision between planetesimals ~4.8 Ma after t0 in a transition or a debris disk. One of the colliding bodies was probably differentiated. The CH metal-rich carbonaceous chondrites contain chondrules formed by different mechanisms. The magnesian non-porphyritic chondrules formed in the CB impact plume ~4.8 Ma after t0. The chemically diverse (magnesian, ferroan, and Al-rich) porphyritic chondrules formed by incomplete melting of isotopically diverse precursors in the protoplanetary disk, most likely prior the CB impact plume event. We conclude that there are multiple mechanisms of chondrule formation that operated over the entire life-time of the disk.

Chondrules↗

NASA NTRSDate not supplied

Planar Investigation of a CobraMRV Reentry Flowfield Using Pulse-Burst, Cross-Correlation DGV

The flowfield around a Co-Optimization Blunt-body Reentry Analysis Mid-lift/drag-ratio Rigid Vehicle (CobraMRV) vehicle is investigated with a combination of high-speed planar laser Mie scattering (PLMS) and pulse-burst cross-correlation Doppler global velocimetry (PB-CC-DGV). Tests were conducted in the NASA Langley 4-foot Supersonic Unitary Plan Wind Tunnel (UPWT) over a range of different tunnel operating conditions and model configurations. Results indicate a complex shock-boundary layer interaction. Scalar information extracted from the PLMS show the evolution of the bow shock structure, while streamwise velocity measurements indicate the spatial evolution of the shock-boundary layer interaction including the growth of the separation shock foot and eventual reacceleration of the flow at farther downstream locations. Assessment of multiple cases show strong Mach and Reynolds numbers driven effects on the character of the shock-boundary layer interactions. Measurement uncertainties ranged from 50 to 150 m/s throughout the region of interest, driven largely by angular uncertainties and instabilities in the laser pointing. The mean accuracy of the freestream measurements was found to be 5.2-percent of tunnel predicted values.

Laser↗

NASA NTRSDate not supplied

Assimilation of Fossil Hydrothermal Sulfide by Early Amazonian Martian Magmas: Implications for Ore Mineralization on Mars

Martian magmas would interact with any hydrosphere present, whether a global ocean [e.g., 1] or an icy (subterranean) hydrosphere [2] creating hydrothermal systems. Volcanogenic massive sulfide (VMS) ores, with Fe-Zn-Pb sulfides, created by hydrothermal deposition associated with a wide range of volcanism would be expected on Mars [3]. Similar to terrestrial komatiites, martian igneous rocks could generate orthomagmatic Ni-sulfide ore deposits by immiscible sulfide liquid segregation [4]. For this to occur, a martian magma would need to flow over (or intrude into) a pre-existing sulfur-rich formation. Here, we elaborate on the first evidence [5-6] of potential orthomagmatic mineralization in two Early Amazonian (2.4 Ga) igneous meteorites [7-8] involving a threestep process: i) formation of Fe-Zn-Pb sulfides, (ii) assimilated by the 2.4 Ga magmas leading to (iii) formation of orthomagmatic Ni-sulfide deposits. These deposits may remain on Mars, but the telltale signs of Zn-Pb enrichment and Ni-Co depletion in the two meteorites provide important insights into martian geology.

M Humayun↗