LiSr_1.650.35B_1.3B'_1.7O₉(B = Ti, Zr; B' = Nb, Ta): new lithium ion conductors based on the perovskite structure

Abstract

We describe the design and synthesis of new lithium ion conductors with the formula, LiSr_1.65?_0.35B_1.3B’_1.7O₉ ( = vacancy; B = Ti, Zr; B’ = Nb, Ta), on the basis of a systematic consideration of the composition-structure-property correlations in the well-known lithium-ion conductor, La_(2/3)-xLi_3x(1/3)-2xTiO₃ (I), as well as the perovskite oxides in Li-A-B,B’-O (A = Ca, Sr, Ba; B = Ti, Zr; B’ = Nb, Ta) systems. A high lithium-ion conductivity of ca · 0.12 S/cm at 360°C is exhibited by LiSr_1.650.35Ti_1.3Ta_1.7O₉ (III) and LiSr_1.650.35Zr_1.3Ta_1.7O₉ (IV), of which the latter containing stable Zr(IV) and Ta(V) oxidation states is likely to be a candidate electrolyte material for all-solid-state lithium battery application. More importantly, we believe the approach described here could be extended to synthesize newer, possibly better, lithium ion conductors.