LiSr₁_.65₀_.35B₁_.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, LiSr1.65□0.35B1.3B‘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)-xLi3x□(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 LiSr1.65□0.35Ti1.3Ta1.7O9 (III) and LiSr1.65□0.35Zr1.3Ta1.7O9 (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.