Electrical conductivity studies of polyvinyl chloride-based electrolytes with double salt system

Polyvinyl chloride (PVC) has electrical conductivity of ∼10−8 S cm−1. It can serve as a host matrix for solvating lithium salts. The highest room temperature electrical conductivity of 5.2 μS cm−1 for a double salt system was achieved for the composition 50 wt% PVC:15 wt% LiCF3SO3:35 wt% LiBF4. The addition of a plasticizer, ethylene carbonate (EC) and/or propylene carbonate (PC) to the above polymer–salt complex helps to increase the ambient electrical conductivity of the electrolyte. It was found that for the complex containing 40 wt% EC, the room temperature electrical conductivity of the 50 wt% PVC:15 wt% LiCF3SO3:35 wt% LiBF4 sample only increased by a factor of about 1.2. Equal amounts of PVC powder were then subjected to different doses of γ-irradiation. The PVC powders were then used to make different films with composition [50 wt% PVC+15 wt% LiCF3SO3+35 wt% LiBF4]0.6+[100 wt% EC]0.4. The film containing the PVC powder irradiated with a dose of ∼104 Gy of γ-irradiation exhibits the highest conductivity of 450 μS cm−1. A double plasticizer system was also prepared and the sample containing the ratio PC/EC ∼7 exhibits the highest electrical conductivity of 2.6 mS cm−1. Hence in this work, it has been shown that the conductivity of the double salt system can be improved by γ-irradiation and using double plasticizers.