Abstract
In this study, the role of ion dissociation on formation of silver nanoparticle and DC conductivityin PVA:AgNO3 based solid polymer electrolyte has been discussed in detail. Samples of silver ion conducting solid polymer electrolyte were prepared by using solution cast technique. Absorption spectroscopy in the ultraviolet–visible (UV–Vis) spectral region was used to investigate the formation of silver nanoparticles. Broad and sharp peaks due to plasmonic silver nanoparticles subjected to ion dissociation have been observed. The influence of dielectric constant on the intensity of surface plasmonic resonance (SPR) peaks attributed to silver nanoparticles was discussed. From impedance plots, the diameter of high frequency semicircle was found to be decreased with increasing salt concentration. The DC conductivity in relation to the dielectric constant was also explained. From the AC conductivity spectra, the dc conductivity was estimated to be close to that calculated from the bulk resistance. The temperature dependence of the DC conductivity was studied and found to follow Arrhenius equation within two distinguished regions. The AC conductivity at different temperatures has been studied to comprehend the ion conduction mechanism. The AC conductivity against frequency was found to obey the universal power law of Jonscher. Three distinct regions were recognized from the spectra of AC conductivity. The frequency exponent (S) was calculated for the dispersive region of the measured AC conductivity spectra. Various models were discussed to explain the behavior of S value with temperature. The behavior of S value with temperature was then used to interpret the DC conductivity pattern against 1000/T. Finally, from the comparison of calculated activation energy (Ea) and maximum barrier height (Wm), deep insights into ion conduction mechanism could be grasped.
Highlights
In recent years, there has been a growing interest in the development of solid polymer electrolytes for various electrochemical device applications, such as electrochemical capacitors, fuel cells, solar cells, high energy density cells and gas sensors [1]
Polyvinyl alcohol (PVA) possesses a carbon chain backbone structure with hydroxyl (OH) groups connected to methane carbons, which can be a source of hydrogen bonding and assist polymer electrolyte (PE) formation [14]
The UV–Vis absorption spectra are recognized to be quite sensitive to the silver nanoparticles formation [4,26]
Summary
There has been a growing interest in the development of solid polymer electrolytes for various electrochemical device applications, such as electrochemical capacitors, fuel cells, solar cells, high energy density cells and gas sensors [1]. The reduction of silver ions to silver nanoparticles has been observed through optical micrograph techniques in PEO:AgSCN based solid polymer electrolytes by Sekhon et al [20]. The reduction of silver ions to metallic silver nanoparticles in chitosan based solid polymer electrolytes has been investigated [4,21,22]. The stability of silver ions in silver–polymer electrolyte membranes is one of the big concerns in electrochemical device application [22].In polar polymers, silver ions reduction to silver nanoparticles has been reported to be an excellent method to prepare polymer composites with small optical band gaps [23]. It is well known that uncommon electrical and optical properties can be exhibited from nanosized metallic materials, which can clearly be different from those of bulk materials [24] Such singular features of nanosized materials can be useful in many device applications. From the comparison of activation energy with maximum barrier heights (W m ), better understandings of ion transport mechanism can be grasped
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