Preparation and characterization of poly (ethyl methacrylate) based polymer electrolytes doped with 1-butyl-3-methylimidazolium trifluoromethanesulfonate

Solution casting technique is used to formulate the matrix of poly (ethyl methacrylate) (PEMA) and lithium trifluoromethanesulfonate (LiTf) with different 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([Bmim][TfO]) ionic liquid content. The increasing addition of [Bmim][TfO] in the PEMA: LiTf matrix increases the ionic conductivity by one order through the imposed plasticizing effect. The highest conductivity of 1.17 × 10−4 S cm−1 is achieved for the composition of PEMA: LiTf: [Bmim][TfO] (21 wt.%: 9 wt.%: 70 wt.%). The [Bmim][TfO]-plasticized matrix exhibits high ionic conductivity due to the interactions between the added constituents, confirmed by the FTIR spectrum, which gives rise to the presence of high concentration of amorphous phase. The increase in the structural disorderliness is seen from the decrease in the intensity of XRD diffraction peak, coherent length and glass transition temperature (Tg). The miscibility of [Bmim][TfO] also provides more presence of transit sites for the hopping of lithium conducting ions (Li+), which ultimately results in high ionic conductivity. The increasing Li+ ions kinetic energy with rise in temperature shows the thermally assisted conductivity mechanism that follows the Arrhenius rule. The dielectric behavior of the polymer electrolytes is also studied. The thermal profile of the matrix increases with increasing addition of [Bmim][TfO] content.