Thomas J. Richardson

SOLID SOLUTION LITHIUM ALLOY CERMET ANODES

Lithium-magnesium solid solution alloys with compositions between Li0.6Mg0.4 and Li0.8Mg0.2 were prepared by melting the component metals in argon. Experiments carried out in a transparent cell confirmed the suppression of dendrite formation on the alloy surface. Diffusion kinetics within the bulk alloy limit the practical current density, particularly during discharging. Heating mixtures of lithium nitride and magnesium provides a convenient method of preparing ceramic-metal composites (“cermets”) containing the solid solution alloy and inert magnesium nitride. The cermets can be formed into a desired shape before or after reaction and may offer a route to higher surface area metallic anodes with improved rate capability.

Optical and Electrical Properties of Mg ∕ Ni Alloy Subjected to Electrochemical Hydrogenation

The work is aimed at studying properties of the Mg–Ni alloy thin film during electrochemical hydrogenation in an alkalineelectrolyte.Wehavesimultaneouslymeasuredthekineticsofthecathodicprocessesundergalvanostaticconditionsandchangesin optical transmission. We have performed in situ ac impedance measurements of gradually hydrogenated films to monitorchangesintheirelectricalproperties.Mg–Nialloysdemonstratehighopticalcontrastduringelectrochemicalhydrogenationduetoswitchingbetweenreflectiveandtransparentstates,excellentreversibilityofthehydrogenation–dehydrogenationreaction,andfairservicetime.Thevalueoftheacimpedancetechniqueforstudyingthecomplexelectricalprocessesaccompanyingtheincorpo-rationofhydrogenintoactivemetalsandalloysisdemonstrated.©2005TheElectrochemicalSociety. @DOI:10.1149/1.2083107 # Allrightsreserved.ManuscriptsubmittedMarch29,2005;revisedmanuscriptreceivedJuly21,2005.AvailableelectronicallyOctober17,2005.

ReF7 and ReOF5 as fluoride ion donors

Abstract Salts containing the ReF6+ ion have been prepared by one-electron oxidation of ReF6 using KrF+ salts. The compounds ReF6+MF6− (M = Au, Sb) are of moderate stability, tending to decompose to ReF7 and the corresponding pentafluoride. This gives rise to isolated ReF7 and MF5 molecules within the ionic lattice, whose presence is demonstrated by Raman spectroscopy. Interaction of ReF6 and PtF6 produced not the salt ReF6+PtF6− (1), but rather the deep red (PtF5)4 when PtF6 was present in excess, and PtF4 when ReF6 was in excess. ReF6 and IrF6 appear to be in equilibrium with ReF7 and (IrF5)4, possibly via an ionic intermediate ReF6+(IrF6·xIrF5)−. The salts ReOF4+MF6− (M = As, Au, Sb) have been characterized. In contrast to the behaviour of IOF5 and IF7, ReOF5 is a better fluoride ion donor than ReF7.