NASICON-type Na1+xZr2SixP3−xO12 electrolytes: progress and perspectives for solid-state sodium metal batteries

Abstract

Solid-state sodium metal batteries (SSMBs) are considered to be the most attractive alternative to lithium-ion batteries on account of their remarkable safety and low cost. Solid-state electrolytes, as a key component, greatly affect the performance of SSMBs. Sodium super ionic conductor (NASICON)-type Na_1+xZr₂Si_xP_3−xO₁₂ (NZSP) electrolytes with excellent mechanical stability, high thermal/chemical stability and high ionic conductivity are some of the most promising electrolytes for SSMBs. The good compatibility of NASICON-type electrolytes with Na metal anodes and high-voltage cathodes is of great significance for SSMBs. This paper reviews the structural characteristics, ion transport mechanism, strategies for enhancing conductivity, and synthesis methods of Na_1+xZr₂Si_xP_3−xO₁₂-based ceramic electrolytes. Simultaneously, it also introduces approaches for addressing the interfacial issues between Na_1+xZr₂Si_xP_3−xO₁₂ electrolytes and solid electrodes. Finally, prospective research directions are also presented to tackle the challenges for the practical application of Na_1+xZr₂Si_xP_3−xO₁₂ electrolytes.