Lithium alloy negative electrodes

The 1996 announcement by Fuji Photo Film of the development of lithium batt eries containing convertible metal oxides has caused a great deal of renewe d interest in lithium alloys as alternative materials for use in the negati ve electrode of rechargeable lithium cells. The earlier work on lithium all oys, both at elevated and ambient temperatures is briefly reviewed. Basic p rinciples relating thermodynamics, phase diagrams and electrochemical prope rties under near-equilibrium conditions are discussed, with the Li-Sn syste m as an example. Second-phase nucleation, and its hindrance under dynamic c onditions plays an important role in determining deviations from equilibriu m behavior. Two general types of composite microstructure electrodes, those with a mixed-conducting matrix, and those with a solid electrolyte matrix, are discussed. The Li-Sn-Si system at elevated temperatures, and the Li-Sn -Cd at ambient temperatures are shown to be examples of mixed-conducting ma trix microstructures. The convertible oxides are an example of the solid el ectrolyte matrix type. Although the reversible capacity can be very large i n this case, the first cycle irreversible capacity required to convert the oxides to alloys may be a significant handicap. (C) 1999 Elsevier Science S .A. All rights reserved.