Concentration of Charge Carriers, Migration, and Stability in Li3OCl Solid Electrolytes

Recently, a new family of lithium-rich antiperovskites, Li(3)OA (A = halogen), which presents superionic conductivity, emerged as a promising both safe and commercially applicable solid electrolyte for lithium ion batteries. In this paper we employed classical atomistic quasi-static calculations to obtain the concentration of lithium vacancies and interstitials for stoichiometric samples of Li3OCl. The obtained concentrations as well as vacancy and interstitial migration energies reinforced the assumption that vacancies are the charge carriers in both stoichiometric and divalent metal doped samples, but raise the possibility that the high ionic conductivity in LiCl-deficient samples are in fact driven by interstitials, in opposition to what has been assumed so far. The Li3OCl stability at higher temperatures was investigated based on Gibbs energies of decomposition from 0 K up to 550 K. They are negative in the whole temperature range, which suggests that there exists a high Gibbs energy barrier between Li3OCl and starter materials preventing decomposition.