Engineering topics
Somoano, R.
Publications and source records attributed to Somoano, R..
High-Cycle-Life Lithium Cell
Lithium-anode electrochemical cell offers increased number of charge/ discharge cycles. Cell uses components selected for compatibility with electrolyte solvent: These materials are wettable and chemically stable. Low vapor pressure and high electrochemical stability of solvent improve cell packaging, handling, and safety. Cell operates at modest temperatures - less than 100 degrees C - and is well suited to automotive, communications, and other applications.
The cycle life chemistry of ambient-temperature secondary lithium cells
The Jet Propulsion Laboratory is involved in a NASA-sponsored research program to demonstrate the feasibility of ambient-temperature secondary lithium batteries for geosynchronous space applications. Encouraging cycle life has been demonstrated in sealed, cathode-limited laboratory cells. However, the cell capacity declines with cycle life. The results of recent studies of the lithium electrode passivation chemistry, and of conductive diluents for TiS2 cathodes and their possible contribution to capacity decline, are here presented. Technical issues associated with the unique operational requirements of a geosynchronous mission are also described.
Charge Control Investigation of Rechargeable Lithium Cells
An ambient temperature rechargeable Li-TiS2 cell was cycled under conditions which simulate aerospace applications. A novel charge/discharge state-of-charge control scheme was used, together with tapered current charging, to overcome deleterious effects associated with end-of-charge and end-of-discharge voltages. The study indicates that Li-TiS2 cells hold promise for eventual synchronous satellite-type applications. Problem areas associated with performance degradation and reconditioning effects are identified.
Low frequency dielectric relaxation in boracites
In order to elucidate the nature of the imperfections which adversely affect pyroelectric processes in boracites, the thermal and dispersive characteristics of the low frequency dielectric response in iron-iodide boracite (Fe3B7O13I) and copper-chloride boracite (Cu3B7O13Cl) have been investigated. These characteristics were measured as a function of crystallographic orientation and applied field in both the ferroelectric and paraelectric states. The low frequency dielectric relaxation of 100 line oriented multi-domain copper-chloride boracite clearly indicates the dipole nature of the lattice imperfections. The activation energies calculated from a noninteracting Debye model, are 0.53 eV in the ferroelectric phase and 0.10 eV in the paraelectric phase.
Factors affecting cycle life in ambient temperature of secondary lithium batteries
Three major factors are discussed: electrode integrity, electrolyte stability, and dendrite formation. It is concluded that elastomers can function as improved binders for rechargeable cathodes. The cathodes can retain integrity under long cycle life with no visual deteriorations. It is found that microelectrodes can be made from powdery cathode materials for voltammetry studies.
Polymeric metallic electrodes for rechargeable battery applications
A review is presented on the status of plastic metal electrodes, emphasizing the use of polyacetylene as a prototype polymeric material. The electrochemical characteristics of polyacetylene are examined; and the potential use of this material, as well as other types of plastic metal electrodes, in batteries is evaluated. Several problem areas which must be solved before polyacetylene can be widely used in battery applications are discussed, including the problem of electrolyte stability, the problem that the depth of discharge and the energy density is limited by the metal-semiconductor transition, and also the poor electrochemical performance of impure material.
Characterization of prototype secondary lithium battery
The performance characteristics of ambient temperature secondary lithium batteries were determined through continuous cycle tests with periodic current and voltage measurements. Cycle life of the lithium anode was found to be an important problem area as was the formation of dentrite breakage and subsequent shorting. Energy density was increased by using more efficient cathode structures.
The synthesis and transport properties of the complex salt /TMPD/ /TCNQ/2
The syntheses and transport properties of the complex salt /TMPD/ /TCNQ/2 are described. At high temperatures, the complex is a magnetic semiconductor with transport properties intermediate between those found in the highly conducting and poorly conducting TCNQ salts. The complex undergoes a transition below 50-60 K to a state exhibiting singlet-triplet behavior with weakly alternating exchange coupling.
Superconductivity in intercalated molybdenum disulfide.
X-ray studies show the existence of two different types of expansions of the intercalated unit cell in both Na and K compounds. Two different phases are also indicated in the superconducting behavior of the K compound. All intercalated samples studied show a superconducting transition. K and Rb compounds become superconductors in the temperature range from 6.5 to 6.0 K. The Na compounds become superconductors at about 4.5 K. In all cases, the superconductivity disappears upon a short exposure of the sample to air. This phenomenon confirms that the superconductivity is due to the presence of the alkali metal.