A review on the impact of phosphate sources and synthesis parameters on ionic conductivity in Na3Zr2Si2PO12 ceramic solid electrolytes

Sodium-ion batteries (SIBs) represent a promising area of advanced battery technology with significant potential across various industries. A critical element in SIBs is the solid electrolyte, which functions both as an ionic conductor and as a separator between the electrodes. Among the various solid electrolytes, NASICON-based ceramic Na₃Zr₂Si₂PO₁₂ (NZSP) has garnered significant attention due to its outstanding mechanical strength, safety, environmental stability, cost-effectiveness and wide electrochemical window. These qualities make NZSP a key enabler in enhancing the performance and safety of SIBs, thereby driving the development of high-performance batteries and fueling extensive research. This review compares various commonly used phosphate sources and outlines the synthesis parameters of NZSP, while also examining recent advancements in its ionic conductivity. Additionally, it addresses the challenges and opportunities associated with NZSP and proposes future directions for improving both NZSP and SIB technologies. Emerging artificial intelligence (AI) and machine learning (ML) approaches are also discussed as powerful tools for optimizing synthesis conditions and enhancing the design of high-performance NASICON-based NZSP solid electrolytes.