Theoretical investigation of Li-rich anti-perovskite with cluster anion for solid electrolytes

Anti-perovskites are a kind of emerging solid electrolyte materials. The lithium rich anti-perovskite Li3OCl has been used as a solid electrolyte for lithium-ion batteries. It is rich in cations and is expected to solve the problem of low ionic conductivity of solid electrolyte materials. On this basis, this work theoretically modulates the ionic conductivity of lithium rich anti-perovskite by replacing halogen with superhalogen. Density functional theory (DFT) calculation results show that Li3OAlF4, Li3SAlF4, Li3SClO4 and Li3SReO4 display low activation energy (similar to 0.2 eV), and their ionic conductivities can reach 10(-2) S cm(-1) at room temperature. The improved ionic conductivities are attributed to the rotation of superhalogen which facilitates the movement of lithium ions; additionally, the volume effect caused by superhalogen is also an important factor. Finally, considering the stability and ionic conductivity, Li3SAlF4 and Li3SReO4 are predicted to be potential solid electrolyte materials for practical applications.