The development of glassy electrolytes for all-solid-state batteries is reviewed. In particular, two strategies for enhancing Li+ conductivity are proposed; one is the addition of oxide to sulphide glasses (in oxysulphide systems) and the other is the precipitation of superionic metastable crystals by careful heat treatment of the glasses. Mechano-chemical synthesis, as well as rapid quenching, has been developed as a new technique for preparing glasses. Superior Li+ conducting solid electrolytes with high conductivities and the low activation energies for conduction have been achieved in the Li2S-P2S5 glass-ceramic system. SnO-based glasses exhibit large specific capacities as negative electrodes in lithium batteries, and their electorchemical performance is related to the local glass structure.
