Validity of LiPON Conductivity Determined by Impedance Spectroscopy

Abstract

A hypothesis that the generally accepted value of the LiPON conductivity should be attributed to the absorption and displacement currents is substantiated. The reason is a small contribution of the drift current due to field screening by the electric double layer. The basis for this assumption is the measurement of the LiPON absorption capacitance, according to which its dielectric constant is about 106. An alternative equivalent circuit containing a non-ideal absorption element is proposed and its impedance is calculated. It is shown that the Bode diagrams of the alternative circuit approximate the experimental curves well. Parameters and the magnitude of electric field screening are calculated based on a proposed model of a double electric layer. Considering the screening effect, the drift conductivity of LiPON is obtained, which is in good agreement with the data on lithium concentration and ion mobility.