Study of the structural, AC electrical conductivity, electric modulus, and dielectric properties of novel PVDF/LiCoO2 nanocomposites for Li-ion batteries

Abstract

In the present article, novel polyvinylidene fluoride (PVDF)/lithium cobalt oxide (LiCoO2) nanocomposite films were prepared using the casting method to use in Li-ion batteries. X-ray diffraction reveals that the deposited LiCoO2 nanoparticles have a hexagonal structure. The AC electrical conductivity σac was measured and investigated using a different range of frequencies and temperatures. The increase in the LiCoO2 content in the PVDF polymeric matrix leads to the formation of the network through the nanocomposites. The dielectric modulus (M′ and M″) and the dielectric parameters (ɛ′ and ɛ″) were studied in detail. The M′ values decrease with the increase in the filler and temperature as the behavior of semiconductor materials. The max values of M″ shifted with a higher frequency after the addition of LiCoO2 and increase of temperature, indicating the temperature dependency of the relaxation time. A single relaxation peak was found, confirming a thermally activated process that passes through a maximum due to the relaxation time. The Cole-Cole (M′ and M″) diagram shows a distinct semicircle, which is attributed to the interfacial phenomena occurring between the components. The nature of the AC electrical conductivity was explained following Juncher’s law. σAC was enhanced due to the movement of charged ions and charge carriers within the nanocomposite samples.