Sodium-conducting ionic liquid-based electrolytes

•Novel PYR14FSI–NaTFSI electrolytes for high safety sodium batteries were prepared.•The electrolytes show melting point down to − 30 °C.•The room temperature conductivity overcomes 1 × 10− 3 S cm− 1.

Mixtures, based on the N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR14TFSI) ionic liquid and the NaTFSI salt, as low flammability and volatility electrolytes for safer sodium electrochemical energy storage devices, were prepared and investigated in terms of thermal and ion-transport properties. The PYR14TFSI–NaTFSI electrolytes showed melting point down to − 30 °C. No difference in terms of ion-transport properties was observed with respect to analogous lithium electrolyte systems. Conductivity values above 1 × 10− 3 S cm− 1 were observed at room temperature.

Graphical abstractThe PYR14TFSI–NaTFSI electrolyte mixtures display room temperature conductivity above 1 × 10− 3 S cm− 1 in combination with a melting point down to − 30 °C.Figure optionsDownload full-size imageDownload as PowerPoint slide