Thermoplastic Polymer Solid Electrolytes from Poly(ethylene oxide) (PEO), ionic liquids and modified Sepiolite

Dr. Pilar Tiemblo has delivered an oral presentation at the XIII Reunión del Grupo Especializado de Polímeros (GEP) RSEQ/RSEF in Girona, Spain

Abstract: Replacement of the liquid electrolyte in solid Li-ion becomes very relevant in the early 90s with the marketing of the first rechargeable batteries. The advantages of a solid versus liquid electrolyte are: lightness, geometric flexibility, easy packing and increased security, among others. However, they have a major disadvantage, its low ionic conductivity. Throughout these years we have proposed variety of systems with solid performance and reasonably high conductivity. However there are solutions in which the preparation and processing of the material is difficult, at which time either the mechanical properties are insufficient or the conductivity is too low. Our research group has designed a kind of material with high content of liquid phase (ethylene carbonate (EC) and propylene (PC), 40% by weight) and matrix polyethylene oxide (PEO) that behave as solids even at temperatures above the melting point of POE, while presenting similar values of conductivities to liquid electrolytes systems. The key is the incorporation ad hoc into the modified sepiolite materials with TPGS3, that is able to act as physical crosslinking and give rise to three-dimensional networks that behave as thermoplastic, so that the material can be processed by extrusion and subsequently molded for example by compression. The group is currently working to replace the EC for other liquids with less security risks, for which they have chosen different ionic liquids (RTILs). The results obtained so far with a (fluorosulphonyl) imide (FSI) of N-butyl-N-methylpyrrolidinium (BMP) are presented here.