Beyond LLTO-based Perovskite Electrolytes for Stable Metal All-Solid-State Batteries

Perovskite-type electrolytes (PTEs) have good room-temperature ionic conductivity but suffer from poor stability against metal anodes, limiting their use in metal all-solid-state batteries. Researchers often focused on doping/alloying PTEs, overlooking thorough investigation of the main framework, namely La, Ti, and O. Herein, we studied the composition-stability relationship of PTEs focusing on their computational thermodynamic, electrochemical, migration barriers, and mechanical properties. The studied PTEs are unsuitable for metal sodium batteries without modifications to reduce migration barriers. LLHfO and LLZrO show promising metastability against metallic Li anodes, though their migration barriers are higher than LLTO. Nonetheless, LLZrO demonstrated partial mechanical instabilities. Mechanical analysis of LLHfO exhibited balanced mechanical properties. Hence, LLHfO proved to be a promising Li-metal-metastable alternative to the archetypal LLTO with enhanced overall performance metrics.