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)S43– 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)S43– 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.