ABSTRACT
Composite polymer electrolytes were prepared from PAN (polyacrylonytrile), lithium perchlorate (LiClO4), and with three different dielectric reinforcements such as lead zirconium titanate (PZT)-12000, barium titanate (BT)-1000, and alumina (Al2O3)-6. Differential scanning calorimetry and X-ray diffractometry, impedance spectroscopy, FTIR, NMR spectroscopy, and scanning electron microscop were employed to reveal the crystalline nature of the electrolytes. The conductivity of the composite polymer electrolytes was measured by impedance spectrometry. Among the three systems, PZT-reinforced composite exhibits maximum ionic conductivity of 3.42 ×10−3 S/cm at room temperature. The ionic conductivity of the polymer composites increases with an increase in dielectric constant of the reinforcement. The composite with alumina reinforcement displayed strongly modified properties with very weak temperature dependence of conductivity. The morphology of PAN gel with ceramic reinforcement depicts the uniform distribution of reinforcement in the polymer matrix. FTIR studies show that the Li+ ion conductivity of PAN-based composite electrolyte is limited by the coordination of Li+ by CN sites of the PAN chain. However, conductivity of Li ion increases with increase in the dielectric constant of ceramic reinforcement. From NMR studies, three types of Li ion environments are observed in PAN-based composite electrolyte and they are (1) solvation shell, (2) vicinity of polymer chain in the presence of ceramic reinforcement, and (3) interactions of Li+ ions with both solvent and polymer.
