Structural Optimization and Phase Stability of Cubic Li7La3Zr2O12 for Solid Electrolyte Application

Abstract

All-solid-state battery is considered as the next-generation batteries due to its high safety and increased energy density, in which the solid electrolyte is one of the key component that determines its performance. The search for stable solid electrolytes with high conductivity is currently an important issue to compete the liquid ones in commercial batteries. The garnet-type structure Li7La3Zr2O12 (LLZO) have attracted great attention, especially the cubic LLZO which is the best conducting Li-oxide garnet reported to date. In this work, the stoichiometric structure of pristine cubic LLZO has been successfully optimized by using the first-principle calculations.This has not been previously reported so far due to the complicated Li disorder. Moreover, the chemical potential diagram is employed to determine the competing phases for phase stability evaluation and is constructed by the thermodynamic conditions of the phase and the constraints imposed by all stable compounds on the Li–La–Zr–O phase diagram. This work is expected to provide a better understanding on the complex cubic LLZO structure as well its phase stability. Figure 1