Equivalent circuit models and analysis of impedance spectra of solid electrolyte  Na0.25Li0.75Zr2(PO4)3

Abstract

Two RC model circuits are connected in series in order to analyze the electrical and dielectric behaviour of mixed alkali Na 0.25 Li 0.75 Zr 2 (PO 4 ) 3 NASICON compound. However, the data obtained could best be described by one RC circuit representing the grain boundary resistance () and capacitance ( ) in the temperature and frequency range 300-600 K and 300 kHz to 1GHz, respectively. The values of the grain boundary activation energy obtained by fitting to the Arrhenius equation in a plot is ~ 0.40 eV, which is close to the bulk activation energy for electrical conduction. The maximum conductivity obtained is 0.3 S/m at 590 K. A non Debye character was observed in the dielectric permitivity in its frequency dependence. However, the temperature dependence of followed a linear behaviour at low temperatures and frequencies but decreased at higher temperatures. Complex non linear least squares fitting of impedance data using a composite circuit shows good fitting results with relative standard deviation less than 0.2 for all the free parameters which is indicative of the accuracy of data obtained. Similar good fitting results, using a generic battery model, suggest the applicability of the material in rechargeable lithium ion batteries.

Effect of Nb substitution on structural, electrical and electrochemical properties of LiTi2(PO4)3 as electrolyte materials for lithium ion batteries

“…Additionally, the peaks may not have been observed as a result of the frequency which may be outside the frequency range in which the coupling of the ions is supposed to lead to a relaxation. At lower temperatures, all the plots show a slow rise in ε r with increase in the temperature, increases the dielectric constant and attaining a maximum value of ε r = 576 at 393 K. In the case of LiTi 2−x Nb x (PO 4 ) 3 with (x = 0.05, 0.075, 0.1 and 0.15) showing that the dielectric response is high compared to what has been reported for NASICON [9,22]…”

Physical Properties of Porous Pure and Zr/Sn-Doped Nanocrystalline BaTiO3 Ceramics

“…It allows the contributions to the overall electrical property by various components in the material to be easily separated. Other workers have used impedance spectroscopy to study other materials [26,27] to gain insight into electrical conduction mechanisms of the materials. In this work, we report the structural and electrical properties of porous BaTiO 3 and Ba(Ti 0.96 Sn x Zr 0.04-x )O 3 (x = 0.02À0.04) ceramics prepared by solid-state and mechanochemical technique.…”