Role of Hard-Acid/Hard-Base Interaction on Structural and Dielectric Behavior of Solid Polymer Electrolytes Based on Chitosan-XCF3SO3(X = Li+, Na+, Ag+)

Solid films of pure chitosan, chitosan-LiCF3SO3, chitosan-NaCF3SO3, and chitosan-AgCF3SO3 were prepared using solution cast technique. The influence of cation size on the chitosan structure has been investigated by X-ray diffraction technique. The interaction between the alkali metal ions and the donor atoms of chitosan polymer is a strong hard-acid/hard-base interaction. It was found that the intensity of crystalline peaks of chitosan decreases with increase of cation size. The impedance analysis shows that ionic transport is high for the high amorphous system. The second semicircle in Z′′-Z′ plots and the surface plasmonic resonance (SPR) peaks in chitosan-AgCF3SO3 sample system reveal the formations of silver metal nanoparticles. It was found that the high amorphous sample exhibits the high dielectric constant and dielectric loss values. The increase of dielectric constant and dielectric loss with temperature for chitosan-salt membranes indicated an increase of charge carrier concentration