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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

The photoelectron spectroscopy of ZnCl2

The ionization energies (IEs) corresponding to the Cl ligand electrons and the Zn 3d electrons in ZnCl2, computed using large Gaussian basis sets and a high level of correlation treatment, are presented. The IEs for the Cl ligand electrons are in excellent agreement with those determined from photoelectron spectra. The IEs corresponding to the Zn 3d electrons agree with experiment relatively well in absolute magnitude, but differ in order. The vibrational frequencies of the ground state agree very well with experiment, and predictions are made for the corresponding frequencies in the positive ion.

Bauschlicher, Charles W., Jr.↗
NASA NTRS1970

Investigation of solid state electrolyte silver-zinc battery

Study of the solid electrolyte ZnCl2-2NH3 rechargeable silver zinc electrochemical cell by X-ray diffraction analysis of the reaction products led to the conclusion that some water is consumed when the cell is discharged. Replacement of ZnCl2-2NH3 by ZnCl2-4Zn(OH)2 gave cells with high internal resistance and limited capacity. The salt formed by exposing a fibrous membrane saturated with ZnCl2 solution to fumes from ammonium carbonate in a dry desiccator comprised ZnCl2-4Zn(OH)2, ZnCl2,3NH4Cl and a third unidentified component. The temperature coefficient of open circuit EMF was nearly zero over the range from -25 C to 50 C. The internal resistance and polarization increased substantially below -25 C. There is some indication that exposure to 50 C for 29 hours causes some deterioration.

Source record↗
NASA NTRS1996

Separator Materials Used in Secondary Alkaline Batteries Characterized and Evaluated

Nickel-cadmium (Ni/Cd) and nickel-hydrogen (Ni/H2) secondary alkaline batteries are vital to aerospace applications. Battery performance and cycle life are significantly affected by the type of separators used in those batteries. A team from NASA Lewis Research Center's Electrochemical Technology Branch developed standardized testing procedures to characterize and evaluate new and existing separator materials to improve performance and cycle life of secondary alkaline batteries. Battery separators must function as good electronic insulators and as efficient electrolyte reservoirs. At present, new types of organic and inorganic separator materials are being developed for Ni/Cd and Ni/H2 batteries. The separator material previously used in the NASA standard Ni/Cd was Pellon 2505, a 100-percent nylon-6 polymer that must be treated with zinc chloride (ZnCl2) to bond the fibers. Because of stricter Environmental Protection Agency regulation of ZnCl2 emissions, the battery community has been searching for new separators to replace Pellon 2505. As of today, two candidate separator materials have been identified; however, neither of the two materials have performed as well as Pellon 2505. The separator test procedures that were devised at Lewis are being implemented to expedite the search for new battery separators. The new test procedures, which are being carried out in the Separator Laboratory at Lewis, have been designed to guarantee accurate evaluations of the properties that are critical for sustaining proper battery operation. These properties include physical and chemical stability, chemical purity, gas permeability, electrolyte retention and distribution, uniformity, porosity, and area resistivity. A manual containing a detailed description of 12 separator test procedures has been drafted and will be used by the battery community to evaluate candidate separator materials for specific applications. These standardized procedures will allow for consistent, uniform, and reliable results that will ensure that separator materials have the desired properties for long life and good performance in secondary alkaline cells.

Source record↗
NASA NTRS1976

Evaluation of selected chemical processes for production of low-cost silicon

Plant construction costs and manufacturing costs were estimated for the production of solar-grade silicon by the reduction of silicon tetrachloride in a fluidized bed of seed particles, and several modifications of the iodide process using either thermal decomposition on heated filaments (rods) or hydrogen reduction in a fluidized bed of seed particles. Energy consumption data for the zinc reduction process and each of the iodide process options are given and all appear to be acceptable from the standpoint of energy pay back. Information is presented on the experimental zinc reduction of SiCl4 and electrolytic recovery of zinc from ZnCl2. All of the experimental work performed thus far has supported the initial assumption as to technical feasibility of producing semiconductor silicon by the zinc reduction or iodide processes proposed. The results of a more thorough thermodynamic evaluation of the iodination of silicon oxide/carbon mixtures are presented which explain apparent inconsistencies in an earlier cursory examination of the system.

Blocher, J. M., Jr.↗
NASA NTRS1978

Evaluation of selected chemical processes for production of low-cost silicon, phases 1 and 2

A miniplant, consisting of a 5 cm-diameter fluidized-bed reactor and associated equipment was used to study the deposition parameters, temperature, reactant composition, seed particle size, bed depth, reactant throughput, and methods of reactant introduction. It was confirmed that the permissible range of fluidized-bed temperature was limited at the lower end by zinc condensation (918 C) and at higher temperatures by rapidly decreasing conversion efficiency. Use of a graded bed temperature was shown to increase the conversion efficiency over that obtained in an isothermal bed. Other aspects of the process such as the condensation and fused-salt electrolysis of the ZnCl2 by-product for recycle of zinc and chlorine were studied to provide information required for design of a 50 MT/year experimental facility. In view of the favorable technical and economic indications obtained, it was recommended that construction and operation of the 50 MT/year experimental facility be implemented.

Blocher, J. M.↗
NASA NTRS1981

Evaluation of selected chemical processes for production of low-cost silicon, phase 3

A Process Development Unit (PDU), which consisted of the four major units of the process, was designed, installed, and experimentally operated. The PDU was sized to 50MT/Yr. The deposition took place in a fluidized bed reactor. As a consequences of the experiments, improvements in the design an operation of these units were undertaken and their experimental limitations were partially established. A parallel program of experimental work demonstrated that Zinc can be vaporized for introduction into the fluidized bed reactor, by direct induction-coupled r.f. energy. Residual zinc in the product can be removed by heat treatment below the melting point of silicon. Current efficiencies of 94 percent and above, and power efficiencies around 40 percent are achievable in the laboratory-scale electrolysis of ZnCl2.

Blocher, J. M., Jr.↗
NASA NTRS1982

Interaction between ATP, metal ions, glycine, and several minerals

Interactions between ATP, glycine and montmorillonite and kaolinite clay minerals in the presence of various metal cations are investigated. The adsorption of adenine nucleotides on clays and Al(OH)3 was measured as a function of pH, and glycine condensation was followed in the presence of ATP, ZnCl2, MgCl2 and either kaolinite or montmorillonite. The amounts of ATP and ADP adsorbed are found to decrease with increasing Ph, and to be considerably enhanced in experiments with Mg(2+)- and Zn(2+)-montmorillonite with respect to Na(+)-montmorillonite. The effects of divalent cations are less marked in kaolinite. Results for Al(OH)3 show the importance of adsorption at clay platelet edges at high pH. The decomposition of ATP during drying at high temperature is observed to be inhibited by small amounts of clay, vacuum, or Mg(2+) or Zn(2+) ions, and to be accompanied by peptide formation in the presence of glycine. Results suggest the importance of Zn(2+) and Mg(2+) in chemical evolution.

Rishpon, J.↗
NASA NTRS1985

Metals Electroprocessing in Molten Salts

The present study seeks to explain the poor quality of solid electrodeposits in molten salts through a consideration of the effects of fluid flow of the electrolyte. Transparent cells allow observation of electrolyte circulation by a laser schlieren optical technique during the electrodeposition of solid zinc from the molten salt electrolyte, ZnCl2 - LiCl-KCl. Experimental variables are current, density, electrolyte composition, and cell geometry. Based on the results of earlier electrodeposition studies as well as reports in the literature, these parameters are identified as having the primary influence on cell performance and deposit quality. Experiments are conducted to measure the fluid flow patterns and the electrochemical cell characteristics, and to correlate this information with the morphology of the solid electrodeposit produced. Specifically, cell voltage, cell current, characteristic time for dendrite evolution, and dendrite growth directions are noted. Their relationship to electrolyte flow patterns and the morphology of the resulting electrodeposit are derived. Results to date indicate that laser schlieren imaging is capable of revealing fluid flow patterns in a molten salt electrolyte.

Sadoway, D. R.↗
NASA NTRS1991

Chemical evaluation of non-woven nylon separators used in Ni/Cd cells

The goals of the chemical analysis was to identify Gates 2505 degradation mechanism, to determine if Eagle-Pitcher 2505 supply suitable for flight, and to assess the 2538 as a candidate replacement, based on chemical findings. Chemical testing strongly indicates that the Gates 2505 stored in Florida had undergone partial chemical deterioration, believed caused by exposure to high humidities and temperature. A suspected role of zinc chloride as a separator concern during storage was not verified in this study (the effect of ZnCl2 on cell/electrode performance was not addressed). No substantial chemical issues or concerns with using EP 2505 as Ni/Cd battery separator for Mars Observer and TOPEX could be found. No chemical issues or concerns with using 2538 as Ni/Cd battery separator were found, in fact, chemical evidence suggest that 2538 may be a better material, as compared to 2505.

Cuddihy, Edward F.↗
NASA NTRS2004

Volatile Element Geochemistry in the Lower Atmosphere of Venus

We computed equilibrium abundances of volatile element compounds as a function of altitude in Venus lower atmosphere. The elements included are generally found in volcanic gases and sublimates on Earth and may be emitted in volcanic gases on Venus or volatilized from its hot surface. We predict: 1) PbS, Bi2S3, or possibly a Pb-Bi sulfosalt are the radar bright heavy metal frost in the Venusian highlands; 2) It should be possible to determine Venus' age by Pb-Pb dating of PbS condensed in the Venusian highlands, which should be a representative sample of Venusian lead; 3) The gases HBr, PbCl2, PbBr2, As4O6, As4S4, Sb4O6, BiSe, InBr, InCl, Hg, TlCl, TlBr, SeS, Se2-7, HI, I, I2, ZnCl2, and S2O have abundances greater than 0.1 ppbv in our nominal model and may be spectroscopically observable; 4) Cu, Ag, Au, Zn, Cd, Ge, and Sn are approx. 100 % condensed at the 740 K (0 km) level on Venus.

Schaefer, L.↗