Crystal structures and ionic conductivity in Li2OHX (X = Cl, Br) antiperovskites

Crystal structures and ionic conductivity of antiperovskites Li2OHX (X ​= ​Cl, Br), which are potential solid electrolyte materials for all-solid-state Li-ion batteries, were investigated. Li2OHCl showed a Pmc21 orthorhombic structure at room temperature and changed to a Pm3‾m cubic one between 27 and 37 ​°C. Li2OHBr, on the other hand, crystallized in a Pm3‾m cubic structure and showed no phase transition in the measured temperature range. The cubic phases of both compounds showed dominant high Li+-ion conductivity, while the orthorhombic phase of Li2OHCl exhibited reduced ionic conductivity. The Li+-ion order in the orthorhombic Li2OHCl makes the crystal structure highly anisotropic and two dimensional, which disturbs the hopping of the Li+ ions. Ionic conductivity for Li2OHCl and Li2OHBr. The cubic phases show dominant high Li+-ion conductivity, while the orthorhombic phase of Li2OHCl exhibited reduced ionic conductivity. [Display omitted]