Tailoring the Lithium-ion Conductivity of Li2OHBr by Substitution of Bromine with Other Halogens

We report that mixed-halogen anti-perovskite-type Li2OHBr1−xXx (X = Cl, I and x = 0–1) materials are prepared by room temperature ball-milling process, and investigate how the halogen mixing affects the total Li+ conductivity. Both solid solution ranges and lattice constants depend on the species of X. Among them, though X = I compounds form solid solution in narrow range of x smaller than 0.15, Li2OHBr0.9I0.1 shows the largest lattice constant and the highest total ionic conductivity at 25 °C (σ25) of 4.9 × 10−6 S cm−1, which is ca. 4 times higher value than that of pristine Li2OHBr. Increasing the lattice constant will be one of the factors to improve total ionic conductivity of the Li2OHBr1−xXx. Mixed-halogen anti-perovskite-type solid electrolytes Li2OHBr1−xXx (X = Cl, I) are synthesized by room-temperature ball-milling process, and their lattice constants and ionic-conducting properties are investigated. It is suggested that the larger lattice constant provides the higher ionic conductivity, and the highest ionic conductivity of 4.9 × 10−6 S/cm is achieved in Li2OHBr0.9I0.1, which is 4 times higher than that of pristine Li2OHBr.