Many new glasses composed of AgI, Ag2O and oxides, MxOy is B2O3, SiO2, GeO2, P2O5, V2O5, As2O5, CrO3, SeO3 or MoO3, were found. Among these oxides. the B2O3- based glasses. that is,the AgI-Ag2O-B2O3 glasses have several unique properties such as (a) very wide glass forming regions, (b) high glass transition temperatures, (c) network structure with BO3 and BO4 groups, and (d) high conductivities of 10-2 to 10-7 Scm-1 at room temperature. This high temperature form of AgI, aAgI, was stabilized in the borate glasses in two wats; one was the rapid melt quenching, and the other was the annealing of glasses at a suitable temperature below the a-b transformation temperature (147 degrees C) for AgI. The latter technique is now usefully applied for the development of glass ceramics as the solid electrolytes for all solid state lithium secondary batteries. Tin oxide containing borate and borophosphate glasses were prepared by the mechanical milling technique as well as melt quenching. These new glasses were proved to work as large capacity negative electrodes for Li+ ion secondary batteries. The capacities and also the glass transition temperatures were strongly related to the amount of four coordinated boron.
