No abstract

Solid electrolytes based on lithium titanium phosphate were prepared, and their phase, porosity of the sintered pellets, and electrical conductivity were studied. The conductivity was increased and the porosity decreased greatly by partially replacing Ti 4+ and ps+ in LiTi2(PO4)s with M 3 § (M s+ = A1 s+, Cr 3+, Ga 3+, Fe s+, Sc s+, In 3+, Lu s § y3+, and La 3+) and Si 4+ ions, respectively. The maximum conductivity at 298 K is 7 • 10 -4 S cm-' for Lil.sM0.3Ti,.7(PO4)s (M = A1 and Sc). The conductivity was considerably increased by the mixing of binders such as Li20 or Li4P207 with LiTi2(PO4)s. The main reason for the conductivity enhancement of these electrolytes seems to be attributable to the increase of the sintered pellet density with the enhancement of the lithium concentration at the grain boundaries.

The all‐solid, lithium rechargeable battery, which if available would find many applications, is one reason for carrying out research into Li⊕‐conducting solids. Fast Li⊕‐conducting ceramic electrolytes are reviewed with regard to their electrical properties and crystal structure. Both non‐oxide based ceramics and oxide materials are considered, and possibilities for further developments—e.g., the preparation of the electrolyte by thin film techniques—are pointed out.