Solid Polymer Electrolyte\nwith High Ionic Conductivity\nvia Layer-by-Layer Deposition

Abstract

A novel multilayer system via layer-by-layer\n(LbL) self-assembly\nby alternatively packing polyethylene glycol (PEG)−α-cyclodextrin\n(αCD) complex and poly­(acrylic acid) (PAA) via hydrogen-bonding\nis designed and investigated in this work. The PEG-αCD inclusion\ncomplex is obtained by supramolecular interaction. Multilayer films\nwith different ratios of αCD are fabricated, and the growth\nbehavior, morphology, thermal properties, and electrical properties\nof the resultant LbL films are systematically characterized. The films\nwith PEG-αCD complex and PAA as building blocks show high ionic\nconductivity reaching up to 2.5 × 10^–5 S cm^–1 under room temperature (52%RH), which is almost two\norders magnitude higher than the PEG/PAA films under the same conditions.\nThe PEG-αCD₁₅/PAA films also possess high water retention\ndue to the large amounts of hydroxyl groups carried by αCD,\nwhich enables the films, after being exposed to a high humidity environment,\nto maintain a high ionic conductivity under a low humidity environment.\nThis PEG-αCD/PAA LbL system provides an insight for designing\npolymer based solid state electrolyte and its application toward electrochemical\ndevices.