Recent progress in NASICON solid electrolytes: Synthesis and applications for all-solid-state sodium-ion batteries

The rise of renewable energy and electrified transportation drives demand for all-solid-state sodium-ion batteries with high safety and energy density. Among the materials investigated, NASICON-type Na 3 Zr 2 Si 2 PO 12 has emerged as a promising solid-state electrolyte due to its three-dimensional open-framework structure and superior Na + conductivity. This review provides a comprehensive analysis of the structural properties of Na 3 Zr 2 Si 2 PO 12 , with particular emphasis on the mechanisms by which various doping strategies influence ionic conductivity. Furthermore, a co-doping approach has been shown to lower activation energy via synergistic effects, thereby significantly improving ionic conductivity. Additionally, various preparation methods can effectively mitigate the formation of impurity phases and enhance material density. Doping-optimised NASICON electrolytes facilitate the development of all-solid-state sodium batteries with improved specific capacity and extended cycling stability. This study paves the way for high-performance solid-state electrolytes and proposes future research on multivariate co-doping and low-temperature sintering.