Effect of Lithium Iodide on transport phenomenon in Lithium Borophosphate glass Electrolyte

Abstract

Ion transport study for the lithium iodide doped Lithium Borophosphate (LBP) glass electrolyte x(LiI):[(100−x).(60Li2O:8B2O3:32P2O5)] has been carried out over a range of composition (x=0 to 25 wt.%). The electrical conductivity has been measured by complex impedance spectroscopy from 303 K to 423 K temperature. The physical parameter and conductivity study indicate to obey the Arrhenius relationship and the frequency dependent conductivity is in consonance with Jonscher's universal power law. The Correlated Barrier Hopping (CBH) model for ion transport is observed to follow in the present glass system. Further investigation of the conductivity has also been carried out to calculate the hopping frequency (ωp), relaxation time (τ), power-law exponent (n) and decoupling index (Rτ). The enthalpy for migration and free energy have been estimated using the frequency-dependent power-law exponent (n) behaviour. Charge dynamics between local states due to the activated hopping process has been discussed according to Anderson- Drago and Elliot's model. To reinforce the Lithium ion transport study, several physical parameters such as density (ρ), molar volume (VO), oxygen packing density (OPD), cation concentration (NLi), the mean distance between cations (R′LiI) and the total number of energy states per unit volume at Fermi level N(Ef) have been calculated using various empirical formulae to discuss the present LBP ionic glass system.