Analysis of ion conduction behavior of Nb- and Zr-doped Li3InCl6-based materials via material simulation

The Li-ion conductivities of Li3InCl6 (LIC), which is a promising chloride solid electrolyte, and its compositional derivatives, Nb5+- and Zr4+-doped LIC, i.e., Li3−2xIn1−xNbxCl6 and Li3−yIn1−yZryCl6, respectively, were experimentally and computationally investigated. An increase in the ionic conductivity caused by Nb5+ or Zr4+ doping, which was due to the increase in Li vacancies, was observed in both the experimental and computational results. Nb5+ doping yielded a larger increase in conductivity at 60 °C. First-principles molecular dynamics studies indicated two factors affecting the Li-ion conductivity under doping with higher-valent ions: (1) the vacancy trapping effect and (2) the reduction in the phase-transition temperature from a Li/vacancy ordered structure to a disordered structure. In particular, in factor (2), the effect of Nb5+ doping is larger than that of Zr4+ doping, which supports the improvement in ionic conductivity at 333 K in the experiment.