Plastic crystal as a plasticizer for enhancing Li+ ion conductivity in PMMA–LiTf polymer electrolyte

In this work, plastic crystal polymer electrolytes (PCPE) composed of polymethyl methacrylate (PMMA), lithium trifluoromethanesulfonate (LiTf), and succinonitrile (SN) were prepared using the solution casting method. The concentration of the plastic crystal SN was varied from 2 wt% to 20 wt%. The ionic conductivity of the PCPEs was measured at room temperature, with a maximum value of 5.75×10⁻⁵ S/cm observed for the PCPE with 10 wt% SN. An increase in the amorphous nature of the PCPE was noted from X-ray diffraction analysis, attributed to the interactions among PMMA, LiTf, and SN. FTIR analysis confirmed the presence of interactions among the components in the samples. A higher dielectric constant was obtained for the PCPE with 10 wt% SN. Dielectric tangent analysis revealed improved salt dissolution at higher concentrations of SN (20 wt%). The thermal stability of the PCPEs was also enhanced with the addition of SN.