Studies of Dielectric Properties and Conductivity of Chitosan-Lithium Triflate Electrolyte

Abstract

A series of solid electrolytes based on natural polymer were prepared by mixing lithium triflate, (LiCF3SO3) into chitosan solutions of various compositions. The dielectric properties and conductivity behavior of as-cast and dried film were studied by using impedance spectrometer. The dielectric properties show that the dielectric loss (ε′′) of both as-cast and dried film decreased with increasing frequency in the low frequency region followed by a peak. It was also found that the appearance of peaks for each sample in the loss tangent (tan δ) suggests the presence of relaxing dipoles in the polymer electrolyte films. In contrast with dried chitosan film, the tan δ peaks of the as-cast one shifted towards the higher frequency side with increasing lithium salt concentration, suggesting the speed-up of relaxation time. The AC conductivities of both samples showed the existence of a frequency-independent plateau region, which can be considered as DC conductivity. The DC conductivity of the as-cast sample, however, is higher than the dried one. It means that the effects of solvent remaining in the sample on electrical properties are much higher than the addition of LiCF3SO3.