Solvent-free methods are provided for synthesizing NSS ionic conductors including but not limited to Se-doped and fluorine-doped NSS ionic conductors, which can be used as solid electrolytes in electrochemical storage devices and providing high ionic conductivity at room temperature and other advantages.

Solvent-free methods are provided for synthesizing NSS ionic conductors including but not limited to Se-doped and fluorine-doped NSS ionic conductors, which can be used as solid electrolytes in electrochemical storage devices and providing high ionic conductivity at room temperature and other advantages.