Energy Storage Science and Technology ›› 2016, Vol. 5 ›› Issue (5): 725-729.doi: 10.12028/j.issn.2095-4239.2016.0024

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DFT investigations on antiperovskite Li3OX(X=F,Cl,Br) superionic conductors

WANG Xuelong, XIAO Ruijuan, LI Hong, CHEN Liquan   

  1. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2016-06-02 Revised:2016-06-20 Online:2016-09-01 Published:2016-09-01

Abstract: As a family of promising inorganic solid electrolyte in csrystallized phase, the antiperovskite superionic conductor with general formula of Li3OX(X=F,Cl,Br) received much attention since the day they were sucssesfully synthesized. However many researches pointed out that Li3OX is thermaldynamically metastable with respect to decomposition to Li2O and LiX. In this paper a comparative study is made between the members of this family by means of first-principle calculations with together the lattice-dynamic simulation under the quasi harmonic approximation. The result shows that they share the same atomic configuration with a cubic unit cell and a wide electrochemical window. However the Gibbs formation energy at different temperature and pressure reveals their distinct theromodynamic stability wich may root in their different radius ratios to the oxygen atom. The simulation results are in qualitive agreement with the experimental condition under which the Li3OCl are synthesized and explain the reason why the thermodynamically meta-stable antiperovskite Li3OX can exist to some extend.

Key words: antiperovskite, solid-state electrolyte, first-principle calculation, thermodynamic stability