(357b) Imidazolium-Based Polymerized Ionic Liquids for Solid Polymer Electrolytes: The Effect of Anion Type

Solid polymer electrolytes (SPEs) with high ionic conductivities are of great interest for energy conversion and storage devices (e.g., fuel cells, batteries, solar cells, actuators, capacitors), in part, because they overcome shortcomings of liquid electrolytes (e.g., leakage, flammability, toxicity, stability). The utilization of ionic liquids (ILs) in SPEs has gained remarkable interest due to the excellent physiochemical properties of ILs (e.g., negligible vapor pressure, nonflammability, high ionic conductivity, good electrochemical, chemical and thermal stability). Recently, polymerized ionic liquids (PILs), a new class of SPEs, have received increased attention for energy applications.

This study focuses on the synthesis and characterization of imidazolium-based PILs. In this work, an imidazolium-based IL monomer, 1-[(2-methacryloyloxy)ethyl]-3-butylimidazolium bromide (MEBIm-Br), was synthesized and subsequently polymerized using conventional free radical polymerization. To investigate the effect of anion type on polymer properties and ion conduction, the polymer precursor, poly(MEBIm-Br), was exchanged with other anions such as tetrafluoroborate (BF4), bis(trifluoromethanesulfonyl) imide (TFSI), trifluoromethanesulfonate (Tf), and hexafluorophosphate (PF6). Also, a novel method was developed to prepare the imidazolium-based PIL with hydroxyl anions. The type of anion was shown to have a significant effect on the glass transition temperature of the polymer and subsequently the ionic conductivity. Additionally, the anion type also had a significant effect on the hydrophilicity of the polymer, where the addition of water to hydrophilic systems resulted in significant increases in ion transport. Detailed results of anion effect on the ion transport will be presented.