LiSr1.650.35B1.3B‘1.7O9 (B = Ti, Zr; B‘ = Nb, Ta):  New Lithium Ion Conductors Based on the Perovskite Structure

We describe the design and synthesis of new lithium ion conductors with the formula, LiSr 1 .65 □ 0 .35 B 1 .3 B‘ 1 .7 O 9 (□ = 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)- x Li 3 x □ ( 1 /3)-2 x TiO 3 ( 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 .65 □ 0 .35 Ti 1 .3 Ta 1 .7 O 9 ( III ) and LiSr 1 .65 □ 0 .35 Zr 1 .3 Ta 1 .7 O 9 ( 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.