Structures, Thermodynamics, and Li+ Mobility of Li10GeP2S12: A First-Principles Analysis

The first-principles and thermodynamic calculations were performed to study structural stability, thermodynamic properties, and Li+ migration mechanism of the superionic conductor Li10GeP2S12 (LGPS). Our calculations show that the zigzag and parallel arrangements of GeS44- and P(1)S-4(3-) units form three types of stable structures. Among them, zigzag-type structures with 2-4 Li+ occupied in the Li4 position were found to be the most stable. Our thermodynamic calculations show that LGPS may be stable at >276 K when configuration and vibration entropies are considered based on disordered arrangement of GeS44- and P(1)S-4(3-) units, and partially occupied Li+. Based on the calculation for minimum energy paths, we found that Li+ migration along the c axis may be more favorable than that in the ab plane, indicating a very weak anisotropy for Li+ migration of LGPS. These structural and mechanistic studies are helpful to design a novel superionic conductor with high performance.