Study Of Polymer Electrolytes Based On Polymeric Ionic Liquid

Since the first reported observations on ionic conductivity in polymeric media were made by Wright and co-workers, solid polymer electrolytes (SPEs) have drawn significant interest. SPEs possess excellent physical and electrochemical properties such as thin-film forming ability, no free liquid phases, the relatively higher ionic conductivity and wider electrochemical window etc. With those excellent properties, SPEs have been widely investigated due to their potential application for various electrochemical devices, including lithium secondary batteries, electrochromic devices, sensors etc. Recently, as a new kind of electrolyte, ionic liquids (ILs) have aroused much attention. Since ILs consist entirely of ions, they generally have high ion concentration and show negligible vapor pressure, high ionic conductivity, good electrochemical and thermal stability.In the second chapter of this paper, a new kind of polymeric ionic liquid:poly(methyl 2-(3-vinylimidazolidin-1-yl)acetate trifluoromethanesulfonimide) (PMVIm-TFSI) was synthesized by solution polymerization. Different composition of polymer electrolytes were prepared by blending PMVIm-TFSI with LiTFSI and (P(MMA-VAc)).'H NMR, FT-IR, DSC, TGA, XRD, SEM, AC impedance results revealed the physical and electrochemical properties improved significantly when PMVIm-TFSI was added into polymer electrolytes consisting of P(MMA-VAc)/LiTFSI. P(MMA-VAc)/PMVIm-TFSI/LiTFSI electrolyte membrane (transmittance>90%) can be used as the ion-conductive layer material for electrochromic devices (ECDs), which revealed excellent electrochromic performance. In the third chapter, ester groups with different chain length are introduced into N-vinyIimidazole for modifying the imidazole ring.2,2-Azobisisobutyronitrile (AIBN) being the initiator with various weight concentration, the solution polymerization method is employed to obtain a family of PILs through the anion exchanging reaction with LiTFSI. Different composition of polymer electrolytes are prepared by blending PILs with LiTFSI and P(MMA-VAc). and are characterized to investigate the effect of chain length and initiator concentration on their physical, electrochemical properties. the results prove that the blending of PILs helps to improve the thermal stability and ionic conductivity of the polymer electrolytes.