Unlocking Li superionic conductivity in face-centred cubic oxides via face-sharing configurations

Area of Science:

• Materials Science
• Solid-State Chemistry
• Electrochemistry

Background:

• Face-centered cubic (fcc) oxides are typically not considered for solid-state electrolytes due to structural limitations for lithium (Li) ion conduction.
• Conventional solid-state electrolytes often face challenges with stability, conductivity, and cost.

Purpose of the Study:

• To demonstrate lithium (Li) superionic conductivity in face-centered cubic (fcc) oxide structures.
• To investigate the role of cation over-stoichiometry in creating favorable Li-ion pathways.
• To explore a new design strategy for solid-state electrolytes.

Main Methods:

• Synthesized over-stoichiometric Li-In-Sn-O compounds with a rocksalt-type lattice.
• Utilized excess lithium to create face-sharing Li configurations within the fcc framework.
• Measured total ionic conductivity and Li-ion migration barriers.

Main Results:

• Achieved a total Li superionic conductivity of 3.38 × 10^-4 S cm^-1 at room temperature.
• Identified a low Li-ion migration barrier of 255 meV, attributed to novel spinel structures.
• Demonstrated that cation over-stoichiometry in fcc oxides can promote fast Li-ion conduction.

Conclusions:

• Face-sharing Li configurations in fcc oxides, achieved via excess Li, enable significant Li superionic conductivity.
• This work opens new avenues for designing solid-state electrolytes within a versatile fcc structural framework.
• The findings provide a foundation for discovering novel, high-performance solid-state electrolytes.