SURFACE TREATMENT OF A SOLID ELECTROLYTE TO LOWER THE INTERFACIAL RESISTANCE BETWEEN THE SOLID ELECTROLYTE AND AN ELECTRODE

Disclosed are electrochemical devices, such as sodium ion conducting solid state electrolytes, sodium battery electrodes, and solid-state sodium metal batteries including these electrodes and solid state electrolytes. One example method for preparing a sodium/sodium-β″-alumina interface with low interfacial resistance and capable of achieving high current density in an electrochemical cell includes the steps of: (a) providing a precursor electrolyte having a resistive surface region, wherein the precursor electrolyte comprises sodium-β″-alumina; (b) removing at least a portion of the resistive surface region; (c) heating the precursor electrolyte thereby forming a solid state electrolyte, and (d) placing a side of the solid state electrolyte in contact with a sodium anode.