Synthesis of Pyrrolidinium-Based Poly(ionic liquid) Electrolytes with Poly(ethylene glycol) Side Chains

The synthesis and characterization of a new family of pyrrolidinium based poly(ionic liquid) (PIL) electrolytes with poly(ethylene glycol) (PEG) pendant groups is reported. The PILs were synthesized from a diallyl methyl amine hydrochloride monomer, which was obtained in large quantities using a modified Eschweiler-Clarke reaction. As additional plasticizers for the PILs, pyrrolidinium ionic liquids (as), also with PEG groups, were synthesized. All obtained PILs and as revealed excellent thermal stabilities to greater than 300 degrees C. Binary electrolyte mixtures were prepared by blending the PILs and ILs in different weight ratios. In addition, a ternary mixture of the best performing PIL and IL and bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) was prepared. The obtained electrolyte blends showed very good ionic conductivities in the best case up to 2.4 mS cm(-1) at 25 degrees C and 10.2 mS cm(-1) at 100 degrees C and outperformed their pyrrolidinium counterparts with alkyl side chain that were synthesized as a reference. It was found that the ionic conductivity of the blends increased with an increase in the PEG chain length of the PILs. The good physicochemical properties of the presented materials make them potential candidates for electrochemical applications such as lithium-ion batteries or dye-sensitized solar cells.