(Invited) Electrolytes for next-generation sodium metal batteries

Developing reliable and cost-effective electrical energy storage systems (EESs) for portable electronics, electric vehicles, and grid storage applications is vital. Na-ion batteries are the most promising alternative technology owing to their natural abundance and low sodium cost. Solid-state batteries (SSBs) have garnered extensive attention for their ability to suppress the safety hazards of organic liquid electrolytes by replacing them with solid electrolytes. Among the various solid electrolytes being explored, our group mainly focuses on NASICON (Sodium superionic conductor) type silicate and solid polymer electrolytes. Sodium silicates are a class of materials with composition, Na_xM_xSi_xO_x (M = rare-earth metals, x = integer (1-10)). They have the advantage of low sintering temperature (~1050 °C) and 3D framework structure containing MO₆ octahedra and SiO₄ tetrahedra providing facile ionic movement. Solid polymer electrolytes (SPE) are known for their flexibility and electrode compatibility. Highly conductive, filler-free composite solid polymer electrolyte films were prepared using poly(vinylidene fluoride), poly(vinyl pyrrolidone) (PVP), and NaPF₆. PVP binder played an essential role in improving Na ion conductivity and excellent plating−stripping performance. This talk will present an overview of these solid electrolytes for next-generation sodium metal batteries.