Department Of Physics
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Item Nanofiller-assisted Na+-conducting polymer nanocomposite for ultracapacitor: structural, dielectric and electrochemical properties(Springer, 2021-01-04T00:00:00) Kamboj, Vashu; Arya, Anil; Tanwar, Shweta; Kumar, Vijay; Sharma, A.L.We report the preparation of ZrO2 nanofiller-incorporated polymer nanocomposite electrolyte based on the PEO-NaPF6 matrix via standard solution cast method. The structure and morphology of polymeric films have been examined with X-ray diffraction and field emission scanning electron microscopy. Different interactions between the polymer, salt and nanofiller have been examined by Fourier transform infrared technique. The temperature-dependent (40�100��C) electrical conductivity has been examined from complex impedance spectroscopy (CIS). The highest ionic conductivity is exhibited by 5�wt% nanofiller-based electrolyte and recorded ~ 2 � 10�4�S�cm?1 at 100��C. The voltage stability window of polymeric film checked from linear sweep voltammetry is about ~ 4�V, and ion transference number close to unity confirms the major contribution from ion conduction. The dielectric properties have been explored in terms of complex permittivity, loss tangent and complex conductivity. The dielectric plots have been further fitted with an associated equation to evaluate principal dielectric parameters. The optimized polymer electrolyte possesses the lowest relaxation time and the highest dielectric constant that suggests the highest ionic conductivity, which is in good correlation with impedance results. The dc conductivity is also highest for the optimum system, and relaxation time decreases with an increase in temperature. The thermal stability of polymer electrolytes is about 200��C, as examined by thermogravimetric analysis (TGA). The ion transport parameters n, ?, D have been evaluated via FTIR, impedance spectroscopy and Bandara and Mellander (B�M) approach. Finally, the optimized polymer nanocomposite film has been used as an electrolyte-cum-separator for the fabrication of a solid-state symmetric supercapacitor. The electrochemical parameters specific capacitance, energy density, power density have been examined from cyclic voltammetry and galvanostatic charge�discharge technique. It may be concluded that nanofiller incorporation is an effective strategy to enhance the properties of electrolyte and has the potential to adopt as an electrolyte-cum-separator for ultracapacitor. � 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature.Item Structural, electrical and ion transport properties of free-standing blended solid polymeric thin films(Springer Verlag, 2019) Arya A.; Sadiq M.; Sharma A.L.Blended solid polymeric thin films based on PEO–PVP complexed with LiBOB were synthesized by solution cast technique. The effect of salt on morphology, structure and electrochemical properties was examined. The XRD and FESEM analyses reveal the enhancement of amorphous content on salt addition. The FTIR spectroscopy evidences the complex formation and presence of various microscopic interactions. The ionic conductivity for the optimized system has been estimated and found to be two orders higher than the salt-free system, i.e., ~ 5.1 × 10−6 S cm−1 (@40 °C), and remains increasing with temperature i.e. 6.5 × 10−4 S cm−1 (@100 °C) for O/Li = 16. The enhancement of ionic conductivity is attributed to increase in the number density of mobile ions as concluded by the Rice and Roth model. The high tion (~ 0.99) evidences the ionic nature of complexed electrolyte. DSC analysis evidences the suppression of crystallinity and shift of glass transition and melting temperature toward lower temperature implies the enhancement of the amorphous content and forms the rubbery nature of the thin films which support the faster ion conductions. Finally, an interaction scheme is proposed for a better explanation of the ion transport on the basis of experimental findings.Item Tailoring of the structural, morphological, electrochemical, and dielectric properties of solid polymer electrolyte(Institute for Ionics, 2019) Arya, A; Sharma, A.L.A solid polymer electrolyte composed of poly(ethylene oxide) and sodium hexafluorophosphate has been synthesized with a varying fraction of succinonitrile via solution cast technique. Impedance spectroscopy, transference number measurements, and linear sweep voltammetry were used to study the electrochemical properties. The 10 wt.% succinonitrile system exhibited the highest ionic conductivity of ~ 2 × 10−5 S cm−1 which is two orders of magnitude higher than the pristine polymer salt system. The high ionic transference number (~ 1) confirms that ion conduction is dominated by ions and displays the voltage stability window of about 4 V. The dielectric permittivity and the relaxation time (τε′,τM,τh) values corresponding to the segmental motion of the polymer chain varies with the variation of succinonitrile content. The relaxation time and double-layer capacitance are in good agreement with the conductivity. Finally, an ion transport mechanism has been proposed to provide a better understanding of ion migration. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.Item Impact of Shape (Nanofiller vs. Nanorod) of TiO2 nanoparticle on Free Standing Solid Polymeric Separator for Energy Storage/Conversion Devices(Wiley, 2018) Arya, Anil; Saykar, Nilesh G; Sharma, Achchhe LalWe report the investigation on examining the impact of nanofiller (NF)- versus nanorod (NR)-shaped titanium oxide(TiO2) nanoparticle on the structural, electrochemical, transport, thermal, and dielectric properties of the solid polymer electrolyte(SPE). Thin SPEfilms comprising of poly(ethylene oxide), sodium hexafluorophosphate, and dispersed with TiO2NF, TiO2NR (synthe-sized by hydrothermal route) has been prepared via solution cast technique. The shape of nanoparticle influences the morphologicaland structural properties as observed infield emission scanning electron microscope and X-ray diffraction analysis. The highest ionicconductivity was exhibited by the NR dispersed system and is higher than NF dispersed system for all recorded concentration consis-tently. It is attributed to the formation of the long-range conductive path with NR when compared with NF. In addition, the electro-chemical stability window is much higher (~5 V) than the NF-doped system. Furthermore, the dielectric properties of SPE wereinvestigated andfitted in the complete frequency window (1 Hz–1 MHz;T=40–100 C@10 C). It is observed that the NR dispersedsystem shows higher dielectric strength and low relaxation time with respect to NF dispersed system. The results suggest that the NRdispersed SPE possess enhanced properties and is more appropriate for an application in high energy density solid-state Na ion batte-ries.Item Structural, Electrical and Ion Transport Properties of Free Standing Blended Solid Polymeric Thin Films(Springer, 2018) Arya, Anil; Sadiq, Mohd; Sharma, Achchhe LalBlended solid polymeric thin films based on PEO–PVP complexed with LiBOB were synthesized by solution cast technique. The effect of salt on morphology, structure and electrochemical properties was examined. The XRD and FESEM analyses reveal the enhancement of amorphous content on salt addition. The FTIR spectroscopy evidences the complex formation and presence of various microscopic interactions. The ionic conductivity for the optimized system has been estimated and found to be two orders higher than the salt-free system, i.e., ~ 5.1 × 10−6 S cm−1 (@40 °C), and remains increasing with temperature i.e. 6.5 × 10−4 S cm−1 (@100 °C) for O/Li = 16. The enhancement of ionic conductivity is attributed to increase in the number density of mobile ions as concluded by the Rice and Roth model. The high tion (~ 0.99) evidences the ionic nature of complexed electrolyte. DSC analysis evidences the suppression of crystallinity and shift of glass transition and melting temperature toward lower temperature implies the enhancement of the amorphous content and forms the rubbery nature of the thin films which support the faster ion conductions. Finally, an interaction scheme is proposed for a better explanation of the ion transport on the basis of experimental findings.Item Temperature and Salt-Dependent Dielectric Properties of Blend Solid Polymer Electrolyte Complexed with LiBOB(Springer, 2019) Arya, Anil; Sharma, Achchhe LalIn the present paper, the temperature and salt-dependent dielectric properties of poly(ethylene oxide) (PEO) and poly(vinyl pyrrolidone) (PVP) blend matrix complexed with LiBOB are investigated in the frequency range 1 Hz to 1 MHz and temperature range 40 °C to 100 °C (@10 °C). The real and imaginary part of the complex permittivity, complex conductivity have been simulated in the whole frequency window and the various fitted parameters were evaluated respectively. The estimated value of the dielectric constant and the ac conductivity increases with the increase of temperature. The lowering of relaxation time and hopping length is observed with the salt addition that is in correlation with the complex conductivity results. The modulus formalism was used to analyze the recorded dielectric data. The dc conductivity, hopping frequency, and segmental motion are strongly coupled with each other as evidenced by the Debye-Stoke-Einstein (DSE) plot. An interaction mechanism has also been proposed to explore the effect of temperature on the hopping length, relaxation time, hopping potential barrier and the segmental motion of the polymer chain.Item Structural, electrical properties and dielectric relaxations in Na+-ion-conducting solid polymer electrolyte(Institute of Physics Publishing, 2018) Arya, A.; Sharma, A.L.In this paper, we have studied the structural, microstructural, electrical, dielectric properties and ion dynamics of a sodium-ion-conducting solid polymer electrolyte film comprising PEO8-NaPF6+ x wt. % succinonitrile. The structural and surface morphology properties have been investigated, respectively using x-ray diffraction and field emission scanning electron microscopy. The complex formation was examined using Fourier transform infrared spectroscopy, and the fraction of free anions/ion pairs obtained via deconvolution. The complex dielectric permittivity and loss tangent has been analyzed across the whole frequency window, and enables us to estimate the DC conductivity, dielectric strength, double layer capacitance and relaxation time. The presence of relaxing dipoles was determined by the addition of succinonitrile (wt./wt.) and the peak shift towards high frequency indicates the decrease of relaxation time. Further, relations among various relaxation times () have been elucidated. The complex conductivity has been examined across the whole frequency window; it obeys the Universal Power Law, and displays strong dependency on succinonitrile content. The sigma representation () was introduced in order to explore the ion dynamics by highlighting the dispersion region in the Cole-Cole plot () in the lower frequency window; increase in the semicircle radius indicates a decrease of relaxation time. This observation is accompanied by enhancement in ionic conductivity and faster ion transport. A convincing, logical scheme to justify the experimental data has been proposed. ? 2018 IOP Publishing Ltd.