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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

12-crown-4 ether-assisted enhancement of ionic conductivity and interfacial kinetics in polyethylene oxide electrolytes

The electrical and electrochemical properties of thin films of polyethylene oxide electrolytes with and without 12-crown-4 ether (12Cr4) are studied as a function of temperature and in the frequency regime from 100 kHz to 0.1 Hz. These measurements were made on electrolytes containing LiCF3SO3, LiBF4, or LiClO4 salts. At a given temperature, the bulk conductivity for a particular salt depends on the 12Cr4 concentration, reaching a maximum for a ratio of 12Cr4 to Li of 0.003.

Nagasubramanian, G.↗
NASA NTRS1990

Effects of 12-Crown-4 ether on the ionic conductivity and electrode kinetics of electrolytes in polyethylene oxide

Results are described of investigations of the electrical and electrochemical properties of thin films of polyethylene oxide (PEO) electrolytes with and without 12-Crown-4 ether (12Cr4) as a function of temperature and in the frequency regime 100 kHz-0.1 Hz. These measurements were made for LiCF3SO3, LiBF4, and LiClO4 salts. At a given temperature, the bulk conductivity, sigma, (S/cm), for a particular salt, depends on the 12Cr4 concentration with sigma reaching a maximum at about 3 mM 12Cr4. Of the three salts studied, the sigma is the highest for PEO/LiBF4 with 3 mM 12Cr4. The ac and dc measurements yield a lower charge transfer resistance for 12Cr4-incorporated samples than for samples without. Plating/stripping of Li occurs at a potential closer to Li(+)/Li for 12Cr4 samples than those without. The conductivities of a thin (about 100 microns) and a thick (400 microns) films are similar.

Nagasubramanian, G.↗
NASA NTRS2002

Solid State Electrolytes Prepared from PEO (360) Silanated Silica

All solid state composite electrolytes were prepared using fumed silica (SiO2) silanated with an oligomeric polyethylene oxide (PEO) silane containing 6-9 ethylene oxide repeat units, a PEO matrix and LiClO4 (8/1 O/Li). The PEO-silane covalently attached to the silica was amorphous, with a T(sub g) that increased from -90 C to -53 C after attachment. The conductivity of films prepared using the PEO-silanated silica increased to approx. 6 x 10(exp -5) S/cm at RT compared with approx. 1 x 10(-5) S/cm for films prepared with unsilanated SiO2.

Maitra, P.↗
NASA NTRS2003

In Situ Raman Microscopy of a Single Graphite Microflake Electrode in a Li(+)-containing Electrolyte

Highly detailed Raman spectra from a single KS-44 graphite microflake electrode as a function of the applied potential have been collected in situ using a Raman microscope and a sealed spectroelectrochemical cell isolated from the laboratory environment. Correlations were found between the Raman spectral features and the various Li(+) intercalation stages while recording in real time Raman spectra during a linear potential scan from 0.7 down ca. 0.0V vs Li/Li(+) at a rate of 0.1 mV/s in a 1M LiClO4 solution in a 1:l (by volume) ethylene carbonate (EC):diethyl carbonate (DEC) mixture. In particular, clearly defined isosbestic points were observed for data collected in the potential range where the transition between dilute phase 1 and phase 4 of lithiated graphite is known to occur, i.e. 0.157 < E < 0.215 vs Li/Li(+). Statistical analysis of the spectroscopic data within this region made it possible to determine independently the fraction of each of the two phases present as a function of potential without relying on coulometric information and then predict, based on the proposed stoichiometry for the transition, a spectrally-derived voltammetric feature.

Shi, Qing-Fang↗