Monolithic electrochromic devices using lithium ion conducting perovskite-type oxides

The electrical conductivities of several perovskite-type lithium ion conductors in the Li-Sr-Nb-Ta-Ti-O system have been investigated. The Li+-ion conductivities of the Ta-compounds were found to be higher than those of the corresponding Nb-compounds, i.e., Li0.3Sr0.6Ta0.5Ti0.5O3 exhibits a bulk ionic conductivity of 1.7 x 10(-4) S/cm at 30 degreesC, while Li0.3Sr0.6Nb0.5Ti0.5O3 shows a value of 5.4 X 10(-6) S/cm at the same temperature. Substitution of Fe in Li0.3Sr0.6Ta0.5Ti0.5O3 decreases the Li+-ion conductivity slightly. The operation of a monolithic (single element) electrochromic devices was demonstrated using perovskite-type Li0.3Sr0.6B0.5Ti0.5O3 (B = Nb, Ta). The tantalum compound exhibited the largest coloration at the positive electrode side by the application of a voltage of 1.5 V and was bleached under short-circuit conditions at 350 degreesC.