Harnessing melt processing for the preparation of mechanically robust thermoplastic vulcanizate electrolytes

We report a new type of polymer blend electrolyte based on the principle of thermoplastic vulcanizates (TPV). TPV materials have been extensively used in the automotive and manufacturing sectors. However, to the best of our knowledge, TPV-based electrolytes have yet to be produced. These electrolytes, obtained via melt-processing, combine the high ionic conductivity and processibility of a thermoplastic phase with the improved mechanical strength of a crosslinked elastomeric phase. TPV electrolytes prepared with poly(caprolactone) (PCL) (thermoplastic phase) and hydrogenated nitrile butadiene rubber (HNBR) (elastomeric phase) are presented in this work. These materials deliver promising results in terms of ionic conductivity, electrochemical stability and mechanical strength. Further improvements in ionic conductivity are obtained by doping the TPV electrolyte with a flame-retardant solvent, triethyl phosphate. The crosslinked nature of the TPV allows both mechanical strength and electrochemical stability to be conserved upon doping which is not possible in non-crosslinked polymer blend electrolytes prepared with PCL and HNBR.