Atomistic Insight into Ion Transport and Conductivity in Ga/Al-Substituted Li7La3Zr2O12 Solid Electrolytes

• DOI: 10.1021/acsami.8b17217
• Publication Date: 2018-12-12T16:49:56Z
• Authors: Fabián A. García ...; Mauricio R. Bonilla; Anna Llordés; Javier Carrasco; Elena Akhmatskaya
• Keywords: Fast ion conductor

Garnet-structured Li7La3Zr2O12 is a promising solid electrolyte for next-generation solid-state Li batteries. However, sufficiently fast Li-ion mobility required battery applications only emerges at high temperatures, upon phase transition to cubic structure. A well-known strategy stabilize the room temperature relies on aliovalent substitution; in particular, substitution of Li+ by Al3+ and Ga3+ ions. Yet, despite having same formal charge, yields higher conductivities (10-3 S/cm) than (10-4 S/cm). The reason such difference ionic conductivity remains mystery. Here, we use molecular dynamic simulations advanced sampling techniques precisely unveil atomistic origin this phenomenon. Our results show that vacancies generated remain adjacent ions, without contributing promotion mobility. while ions tend allow limited diffusion within their immediate surroundings, less repulsive interactions associated with lead complete blockage neighboring paths. This effect magnified lower temperatures explains observed Ga-substituted systems. Overall, study provides valuable insight into fundamental ion transport mechanism bulk Ga/Al-substituted paves way rationalizing design strategies enhancing these materials.