Rising the molecular mobility of polyvinyl butyral by plasticizers: towards energy storage applications

The versatile behaviour of poly-vinylbutyral (PVB) and its ability to form quasi-solid polymer electrolytes (SPE) with reliable ionic mobility, has been investigated over the temperature range from 120 K to 350 K, by mechanical and dielectric spectroscopic measurements. Enhancements in the polymer chain flexibility, due to the addition of low molar mass organic liquid plasticizers (acetonitrile, AcN, and methoxy-propionitrile, MPN) favouring the long-range motion of charge carriers, give rise to a room temperature ionic conductivity which in the hybrid PVB/MPN/LiI system increases of about 3 and 9 orders of magnitude with respect to the counterparts PVB/LiI and pure dry-PVB system, respectively. This result proves the existence of coupling between cooperative segmental motion and ion dynamics in such kind of materials.