Effect of Cation Substitution on the Sodium Ionic Conductivity of Nasicon-Type Solid Electrolyte

The invention of secondary batteries technology is a milestone in the electronic industry. However, the liquid organic electrolytes suffer from safety issues such as flammability and explosion. This give rise to the progress of new solid electrolytes as non-flammable alternatives. Another obstacle that prevents all-solid-state electrolytes from practical use is the high contact resistance between electrode and electrolyte which results in low ionic conductivity. Therefore, our study aims to develop a chemically stable sodium solid electrolyte with high ionic conductivity at room temperature. In this study, we modified a NAISCON-type sodium ionic solid electrolyte by cation substitution. By using NASICON/polymer film, we reduced the contact resistance between electrolyte and electrodes. The modified materials were analyzed by scanning electron microscopy, X-ray diffraction analysis, and electrochemical impedance spectroscopy measurements. An ionic conductivity up to 10 -4 S cm -1 at room temperature was obtained. The modified NASICON-type sodium ionic solid electrolyte was then assembled into a full-cell system to demonstrate its applications in all-solid-state sodium ion batteries. Keywords: solid electrolytes, polymer film