Wet Mechanical Milling Induced Phase Transition to Cubic Anti-Perovskite Li_2OHCl

Anti-perovskite solid-state electrolyte Li_2OHCl usually exhibits orthorhombic phase and low ionic conductivity at room temperature. However, its ionic conductivity increases greatly when the temperature is up to 40 ℃, while it goes through an orthorhombic-to-cubic phase transition. The cubic Li_2OHCl with high ionic conductivity is stabilized at room temperature and even lower temperature about 10 ℃ by a simple synthesis method of wet mechanical milling. The cubic Li_2OHCl prepared by this method performs an ionic conductivity of 4.27 \times 10^-6 S/cm at room temperature, about one order of magnitude higher than that of the orthorhombic Li_2OHCl. The phase-transition temperature is decreased to around 10 ℃. Moreover, it can still remain cubic phase after heat treatment at 210 ℃. This work delivers a huge potential of fabricating high ionic conductivity phase anti-perovskite solid-state electrolyte materials by wet mechanical milling.