Unraveling the Fast Ionic Conduction in NASICON-Type Materials

Nonflammable solid-state electrolytes with high ionic conductivity are essential for improving the safety and energy density of all-solid-state batteries (ASSBs). The Na superionic conductor (NASICON) framework is extensively researched as a potential solid-state electrolyte because of its ability to achieve high ionic conductivity. Various theories have been proposed to explain the origins of this high ionic conductivity in NASICON, which led to both overlaps and ambiguities. In this work, we will present a comprehensive theoretical framework, supported by experimental verification with controlled variables, that consolidates all known mechanisms to boost ionic conductivity in NASICON. It will provide design principles NASICON with superionic conductivity, promoting the development of solid electrolytes for safer and higher energy density of all-solid-state batteries.