Safe sodium-ion battery using hybrid electrolytes of organic solvent/pyrrolidinium ionic liquid

Abstract

Ionic liquids (ILs) have been considered as an alternative class of electrolytes compared to conventional carbonate solvents in rechargeable lithium/sodium batteries. However, the drawbacks of ILs are their reducing ionic conductivity and their large viscosity. Therefore, mixtures of alkyl carbonate solvents with an IL and a sodium bis(trifluoromethanesulfonyl) imide (NaTFSI) have been investigated to develop new electrolytes for sodium-ion batteries. In this work, N- Butyl-N-methylpyrroIidinium bis(trifluoro-methanesulfonyl) imide (Py₁₄TFSI) was used as co-solvent mixing with commercial electrolytes based on the carbonate, i.e. EC-PC (1:1), EC-DMC (1:1), and EC-PC-DMC (3:1:1).