Boosting Ionic Conductivity by Ordering Nanoparticles within All-Polymer Poly(ethylene oxide) (PEO) Nanocomposites

In this work, we demonstrate that the ordering of ion-conducting nanoparticles within the interlamellar regions of semicrystalline poly-(ethylene oxide) (PEO) enhances its ionic conductivity. Specifically, lithium sulfonamide functional polymeric methacrylic nanoparticles (NPs) measuring 26.4 ± 5.6 nm were aligned within a PEO matrix by controlling the crystallization rate of PEO. Polarized light optical microscopy (PLOM) revealed that the temperature range between 52 and 56 °C allows for sufficiently slow crystallization kinetics to achieve NP ordering. This ordering was observed by using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). The alignment of the NPs results in an 8-fold increase in the ionic conductivity of the nanocomposite polymer electrolyte at room temperature, exhibiting lithium single-ion conducting behavior and achieving a value of 4.6 × 10^-5 S cm^-1 at 80 °C.