A “Cold Sinter and Regrowth” Framework for Increasing Ionic Conductivity in Na-LSX Solid-State Electrolytes

Abstract Sodium-based zeolites are promising as solid-state electrolytes in emerging battery technologies. However, their implementation is limited by the inability of sodium low-silica zeolite X (Na-LSX) crystals to be densified through traditional thermal sintering methods. Therefore, there is a need to develop facile ways to achieve dense and conductive zeolite electrolytes. In this work, we successfully densify Na-LSX using a cold sintering method and demonstrate the ability of post-cold-sintering regrowth treatment methods to increase conductivity to approximately six times greater than that reached with a cold-sintered pellet. BET analysis, PXRD, and SEM are used to explore the mechanism of conductivity increase. Electrolytes created in this study achieve conductivity on the order of 10−7 S/cm at room temperature, with the best-performing samples reaching 10−4 S/cm above 180 °C. At the same time, these samples maintain high density and desirable mechanical properties, showing the ability of simple methods to create functional materials for future implementation.