Solid electrolytes for flexible Li-ion batteries

Several Solid Polymer Electrolytes (SPE) have been prepared using poly(ethylene oxide), three different room temperature ionic liquids (RTIL), lithium bis-(trifluoromethane)sulfonimide as salt (LiTFSI) and sepiolite coated with D--Tocopherol Polyethylenglycol 1000 succinate (TPGS-S) as reinforcement. Three different molecular weight for PEO were used (5∙10⁶, 2∙10⁶ and 2∙10⁵ Daltons), TPGS-S content and Polymer-Salt-RTIL ratios were varied in order to see the influence on the overall conductivities, ionic diffusion, thermal stability and rheological behaviour. The overall conductivity obtained with Impedance Electrochemical Spectroscopy (IES) were close to 10-3 S∙cm-1 at room temperature and materials presents a pseudo-solid character till 90ºC in all samples excepting those with lower molecular weight or the one prepared without TPGS-S. The Li diffusion coefficient shows that conductivity owed to the salt is approximately the third