The effect of carbonate-phthalate plasticizers on structural, morphological and electrical properties of polyacrylonitrile-based solid polymer electrolytes

Polyacrylonitrile (PAN) based solid polymer electrolyte consisting lithium tetrafluoroborate (LiBF4), ethylene carbonate (EC) and dimethyl phthalate (DMP) have been prepared using solution casting method. Comparative studies were done on unplasticized PAN-LiBF4 system and the PAN plasticized system with the novel binary plasticizers of EC and DMP in the ratio of 1:1 by the variation of LiBF4 concentration. The highest room temperature conductivity of electrolyte in PAN-LiBF4 system is 1.83 × 10−3 S cm−1 while 1.08 × 10−2 S cm−1 is obtained from PAN-EC-DMP-LiBF4 system. The complexation and structure of polymer electrolytes have been investigated as function of LiBF4 content at different weight percentages. The morphology and crystalline phase of polymer host is completely changed on the addition of salt and plasticizers. The fraction of free ions is greatly dependent on the amount of salt and the presence of plasticizers.