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 muS 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 gamma -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 similar to 10(4) Gy of gamma -irradiation exhibits the highest conductivity of 450 muS cm(-1). A double plasticizer system was also prepared and the sample containing the ratio PC/EC similar to7 exhibits the highest electrical conductivity of 1.6 mS cm(-1). Hence in this work, it has been shown that the conductivity of the double salt system can be improved by gamma -irradiation and using double plasticizers. (C) 2000 Elsevier Science B.V. All rights reserved.