Impedance Analysis of Polyaniline in Comparison with Some Conventional Solid Electrolytes.

Doped polyaniline (PANI) is well-known as an electronic (polaronic) conductor and mostly is used as semiconductor in various applications. However, in the literature there are examples of employment of the acid doped form of PANI as electrolytic filler in proton exchange membranes. In order to distinguish between two types of conduction, in the present study powdered samples of polyaniline, either in the form of emeraldine base (PANI-EB) or in the form doped with camphorsulfonic acid (PANI-CSA), were investigated using impedance spectroscopy both in the dry state and in contact with liquid water. The obtained spectra were compared with the spectra of such conventional solid electrolytes, as zeolites X and ZSM5 and a strong electrolyte boron orthophosphate, acquired in identical conditions. The most important dissimilarity between conventional electrolytes and PANI was that ion diffusion dominates in the impedance response of the formers, whereas the behavior of PANI is under control of electron/hole displacement and the diffusion part is quite inessential. This corroborates the results of analysis of temperature dependence of PANI conductivity, which revealed values of activation energy twice as large as typical solid electrolytes. Equivalent circuits, simulating the impedance responses of all materials, were built up and used to estimate a possible diffusion coefficient of cations in the comparable solids. It was found that the diffusion in a strong electrolyte such as BPO4 is ∼2 orders of magnitude faster than evaluated for zeolites and ∼4 orders higher than what was PANI estimation. A conclusion was made that the slow cation diffusion both in protonated and in base form of PANI makes them less efficient solid electrolytes than conventional materials.

Effects of the Photovoltaic Distributed Generation on Electricity Distribution System Voltage - Updated Review

ABSTRACT Concerns about the environment and a growing demand for electricity have led to the intensive search for renewable energy sources. Photovoltaic solar energy, in the form of distributed generation, has shown a very high growth rate to an extent that in some regions it will be adopted on a large scale, thus being responsible for the supply of a significant portion of the load of this region. Some factors have favored the adoption of distributed generation: the drop in the price of solar panels and inverters, as well as its easy installation and maintenance. However, the large-scale adoption of solar distributed generation brings new challenges to the power distribution system. Network voltage control is an example. In conventional systems, voltage control is a properly addressed problem, but in networks with the presence of distributed generation, where at certain times of the day reverse energy flows can be observed, more detailed studies on voltage behavior are necessary concerning the power quality. This article makes an analysis of relevant studies on the effects that the insertion of photovoltaic distributed generation can cause in the voltage of the electric power distribution system under the optics of two phenomena: the fluctuation and the voltage ripple.