Lithium ion conduction in extreme polymer in salt regime

Abstract

Thin films of lithium salt containing polymer composites were prepared from LiI, Li₂SO₄ and Li₃PO₄ with PEO, PVA and PEO-PVA (50:50) blends by solution casting method, for various salt concentration (10, 15, 20 mole %). The conductivity and dielectric measurements were carried out on these films as a function of frequency at various temperatures. The highest conductivity was observed in LiI-polymer composites. The variation of conductivity with salt concentration has been explained on the basis of percolation path. In the case of Li₂SO₄ and Li₃PO₄ composites, the variation of conductivity with salt composition is found to depend more on the nature of coordination of Li⁺ ions in the composites rather than the mole % of salt itself. AC conductivity and dielectric relaxation behavior of these composites were also studied and the results are discussed.