Physics - Research Publications
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Item STRUCTURAL AND ELECTROCHEMICAL PROPERTIES OF INTERCALATED AND DISPERSED TYPE POLYMER NANOCOMPOSITE FILMS(Central University of Punjab, 2019) Arya, Anil; Sharma, A. L.The renewable and green source of energy now becomes the burning topic for worldwide research among the scientists. The demand for such energy resources is increasing day by day and it becomes the lifeblood of modern society. Global warming, finite fossil-fuel supplies, and city pollution conspire to make the use of environmentfriendly energy sources. Due to the enlarged dependency of a modern human being on energy resources in every sector and a limited supply of fossil fuels, leads to two main problematic consequences: (1) vulnerability of nation-states to fossil-fuel imports and (2) CO2 emissions that are acidifying our oceans and creating global warming. The controlled environment/climate has drawn the attention of the scientific community towards development and replacement of fossil fuels by an alternative/efficient energy resources. The prospective renewable energy resources are solar, tidal, hydro, wind energy etc. Next challenge comes to store it and could be supplied as per the demand. The said challenge could be overcome through the electrochemical storage/conversion devices (ESCDs) like supercapacitor, Lithium-ion batteries (LIB) and fuel cells. Especially, LIB having the ability to the portability of stored energy and to deliver it as and when required without gaseous exhaust, unlike fossil fuels. A secondary battery converts chemical energy into electrical energy and vice versa. Its structure is composed of a positive electrode as a cathode, a negative electrode as an anode, and electrolyte. Simultaneous movement of ions and electrons occurs in the battery system; ions flow through the electrolyte while electrons are generated at the anode and flow towards the cathode via an external circuit. The heart of the battery is the electrolyte as it is sandwiched between both electrodes and participate in charging/discharging. Although all the three components affect the overall cell performance, the electrolyte is dominating in nature and deciding the specific capacity, energy density, working voltage and the lifespan of the battery. Various types of electrolytes are liquid electrolytes, semi-gel and gel electrolytes. However, safety issues with lithium-metal anodes, the reaction of volatile/flammable organic solvents and the leakage of electrolytes have hindered the commercialization of any lithium-ion battery based on such electrolyte. The drawbacks associated with the battery comprising of above-mentioned electrolyte pushes us to develop new generation solid state polymer nanocomposite films (PNC films) which could possess inherent safety and good compatibility with electrodes as compared with liquid, semi-gel and gel electrolytes. v PNC films have numerous advantages like they are light in weight, flexible, have interfacial compatibility, no leakage issue and are very processable. Most importantly, they are very safe. SPEs are prepared by dissolving lithium salts in a high-molecularweight polymer matrix. The polymer acts as the host for the transmission of lithium ions through the motion of polymer segments. Solid polymer based electrolytes appear to be attractive as they can compensate for the volume changes of electrodes by elastic and plastic deformation. A PEO-based SPE is the most preferred polymer host in the research system due to its flexible backbone and ability to solvate lithium ions, with the coordination number dependent upon the salt concentration and identity of the anion. The main advantage of a PEO is its high solvation power. Hence it can form a complex easily with many alkali salts and provides a direct path for cation migration due to the presence of the ether group in the polymer backbone. But the low conductivity value (10–10 S cm−1 ) and poor mechanical properties of PEOs at ambient temperatures limit their use in devices. Many approaches have been explored to improve the ionic conductivity in order to suppress the concentration polarization and desirable electrochemical properties such as polymer blending, cross-linking, the addition of nano-sized fillers etc. Out of these approaches at host polymer level blending seems more appropriate and justified. Further to scale the relevant properties parameters by minimizing the concentration polarization, two novel approach i.e. (i) nanofiller dispersed polymer nanocomposites, and (ii) intercalated polymer nanocomposites have been adopted. The idea behind using nanofiller was the expectation to get percolation pathways composed of inorganic fillers grains through a flexible polymeric matrix. Such a phenomenon could lead to an increase in ionic conductivity followed, possibly, by an enhancement of the cation transport number while preserving mechanical properties and flexibility of the composite electrolyte prepared in the thin film configuration. The second one is also a thought-provoking approach and plays key role in (i) suppressing the concentration polarization by avoiding anion mobility, (ii) enhancement of the ion migration by allowing the cation coordinated polymer chain confinement in clay galleries, and (iii) negative surface charge on clay acts as Lewis acid and competes with Li+ cation to form complex with polymer which reduces ion coupling. An attempt has been made to understand the role of nanofiller and nanoclay in dispersed and intercalated blend polymer nanocomposites prepared by solution cast technique. A strong correlation exists between crystallinity, conductivity, free ion area, the number density of charge carriers, ion mobility, diffusion coefficient, activation energy, and glass transition temperature. Polymer-intercalated polymer nanocomposites display remarkable higher ionic conductivity, broad voltage stability window, high specific capacity and open-circuit voltage than the dispersed based polymer nanocomposites. Here we provide a cumulative account of an efficient polymer nanocomposite materials to identify their importance in the energy storage/conversion devices.Item Electrolyte for Energy Storage/Conversion (Li+, Na+, Mg2+) Devices Based on PVC and Their Associated Polymer: A Comprehensive Review(Springer, 2019) Arya, Anil; Sharma, Achchhe LalEncouraged by the first report of ionic conductivity in 1973 and the consequent boom for the need of clean and green renewable energy resources, there has been a marked increase toward R&D of polymer electrolytes cum separator for energy storage devices. The most suitable alternative to the conventional energy storage devices is battery and it has the potential to fulfill the energy demand and could be used for storing energy produced from different alternative resources, i.e., wind/hydro/solar energy. Electrolyte is a key component of battery that plays a crucial role in its overall performance. The draft of the article is an attempt to present a coherent yet concise review of Li, Na, and Mg batteries using polymer electrolytes. The main topics given focus in this review are an introduction to properties shaping the polymer electrolytes, types of polymer electrolytes, and properties of constituents of polymer electrolytes (polymer host, salt, solvent, ionic liquid, plasticizer, nanofiller, nanoclay, nanorod, nanowire). The approaches to enhance the electrochemical properties are presented with a suitable ion transport mechanism. A special section is introduced to cover dendrite growth and strategies to suppress it. Important preparation methods and characterization techniques are introduced. The synopses of the experimental investigations are presented for ionic liquid/gel/composite polymer electrolytes. Finally, the future outlook highlights the further development for the next-generation energy storage devices.Item Polymer Nanocomposites: Synthesis and characterization(Springer, 2018) Arya, Anil; Sharma, Achchhe LalThis chapter deals with the fundamental properties of polymer nanocomposites (PNC) and their characteristics that play a significant role in deciding their capability for the advanced energy storage device. The various synthesization methods used for the preparation of the polymer electrolytes are described followed by the characterization techniques used for the analysis. The properties of the polymer host, salt, nanofiller, ionic liquid, plasticizer and nanoclay/nanorod/nanowire are described. Various ion transport mechanism with different nanoparticle dispersion in polymer electrolytes are highlighted. The various important results are summarized and a pathway is built to fulfill the dream of the future renewable source of energy that is economical and environmental benign. Chapter motivation is focused on the investigation of the role of polymer host, aspect ratio, surface area, nanoparticle shape and size in terms of boosting the electrolytic/electrochemical properties of PNC. It will certainly help in order to open new doors toward the development of the advanced polymeric materials with overall balancing property for enhancement of the fast solid state ionic conductor which would be revolutionized the energy storage/conversion device technology.Item Effect of salt concentration on dielectric properties of Li-ion conducting blend polymer electrolytes(Springer, 2018) Arya, Anil; Sharma, Achchhe LalIn the present article, we have studied the effect of the salt concentration (LiPF6) on transport properties and ion dynamics of blend solid polymer electrolyte (PEO-PAN) prepared by solution cast technique. Fourier transform infrared (FTIR) spectroscopy confirms the presence of microscopic interactions such as polymer-ion and ion-ion interaction evidenced by a change in peak area of anion stretching mode. The fraction of free anions and ion pairs obtained from the analysis of FTIR implies that both influence the ionic conductivity with different salt concentration. The complex dielectric permittivity, dielectric loss, complex conductivity have been analyzed and fitted in the entire frequency range (1 Hz-1 MHz) at room temperature. The addition of salt augments the dielectric constant and shift of relaxation peak in loss tangent plot toward high frequency indicates a decrease of relaxation time. We have implemented the Sigma representation (σ'' vs. σ') for solid lithium ion conducting films which provide better insight toward understating of the dispersion region in Cole-Cole plot (ε'' vs. ε') in lower frequency window. The dielectric strength, relaxation time and hopping frequency are in correlation with the conductivity which reveals the authenticity of results. Finally, the ion transport mechanism was proposed for getting the better understanding of the ion migration in the polymer matrix.Item Dielectric Relaxations and Transport Properties Parameter analysis of novel blended solid polymer electrolyte for Sodium Ion Rechargeable Batteries(Springer, 2019) Pritam; Arya, Anil; Sharma, Achchhe LalA novel blended solid polymer electrolyte comprising polyethylene oxide and polyvinylpyrrolidone polymers for blending and sodium nitrate (NaNO3) as ion conducting species has been optimized via standard solution-cast technique. XRD, FESEM, and FTIR were performed to obtain the information about the structural changes, morphology, and microstructural changes (polymer–ion and ion–ion interactions) of the solid polymer electrolyte films. The electrochemical impedance spectroscopy, linear sweep voltammetry, and i–t characteristics were performed to evaluate the ionic conductivity, voltage stability window, and ion transference number. The impedance study was done in a broad temperature range (40–100 °C). The DSC and TGA were used to obtain information about the thermal transitions and thermal stability of prepared films. The ion dynamics is further investigated by analyzing the complex permittivity, loss tangent, and complex conductivity. All the plots were fitted through established theoretical model/expressions in whole frequency window to obtain dielectric strength, ion conduction path behavior, and relaxation time. Transport parameters such as number density (n), mobility (μ), and diffusion coefficient (D) of mobile ions were obtained by three methods and compared satisfactorily. Lastly, a coherent mechanism for the migration of charge transport carriers within the solid polymer composites has been proposed based on the performed experimental outcomeItem 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 Microstructural and Electrochemical Properties of Dispersed Type Polymer Nanocomposite Films(IOP, 2018) Arya, Anil; Sharma, Achchhe LalFree-standing solid polymer nanocomposite (PEO–PVC) + LiPF6-TiO2 films have been prepared through a standard solution-cast technique. The improvement in structural, microstructural and electrochemical properties has been observed on the dispersion of nanofiller in polymer salt complex. X-ray diffraction studies clearly reflect the formation of complex formation, as no corresponding salt peak appeared in the diffractograms. The Fourier transform infrared analysis suggested clear and convincing evidence of polymer–ion, ion–ion and polymer–ion-nanofiller interaction. The highest ionic conductivity of the prepared solid polymer electrolyte (SPE) films is ~5 × 10−5 S cm−1 for 7 wt.% TiO2. The linear sweep voltammetry provides the electrochemical stability window of the prepared SPE films, about ~3.5 V. The ion transference number has been estimated, t ion = 0.99 through the DC polarization technique. Dielectric spectroscopic studies were performed to understand the ion transport process in polymer electrolytes. All solid polymer electrolytes possess good thermal stability up to 300 °C. Differential scanning calorimetry analysis confirms the decrease of the melting temperature and signal of glass transition temperature with the addition of nanofiller, which indicates the decrease of crystallinity of the polymer matrix. An absolute correlation between diffusion coefficient (D), ion mobility (µ), number density (n), double-layer capacitance (C dl), glass transition temperature, melting temperature (T m), free ion area (%) and conductivity (σ) has been observed. A convincing model to study the role of nanofiller in a polymer salt complex has been proposed, which supports the experimental findings. The prepared polymer electrolyte system with significant ionic conductivity, high ionic transference number, and good thermal and voltage stability could be suggested as a potential candidate as electrolyte cum separator for the fabrication of a rechargeable lithium-ion battery system.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 Effect of Nano-Filler on the Properties of Polymer Nanocomposite Films of PEO/PAN Complexed with NaPF 6(Journal of Materials Science and Engineering B 5, 2016) Bhatt, Chandni; Swaroop, Ram; Arya, Anil; Sharma, A. L.Free standing transparent PNC (Polymer nanocomposite) films based on PEO/PAN + NaPF 6 with different concentration (wt./wt.) filler of nano sized (TiO 2 ) is synthesized by using standard solution cast technique. HRXRD (High resolution X -ray diffraction) and FESEM (Field emission scanning electron microscopy) have been performed to see the structural and microstructural behavior of the PNC films. The microscopic interaction among polymer, salt and nano-ceramic filler has been analyzed by FTIR (Fourier transformed infra-red) spectroscopy. The reduction of ion pair formation in polymeric separator is clearly observed on addition of nano-filler in the polymer salt complex film. Electrical (ionic/electronic) conductivity has been estimated (~ 10 -4 S/cm) optimized PNC films concentration of nanofiller (15 Wt.%). The estimated value of electrical conductivity is well corroborated by FTIR study. Thermal analysis has been done with thermo gravimetry analysis to find out thermal stability of PNC films. Transport properties associated due to majority mobile carriers ions and only negligible participation from electrons was observed through transport number analysis. The band gap (i.e. direct as well as indirect) decreases on the addition of nano-filler observed from the optical analysis. The estimated result of the prepared PNC films are at par with desired value for the device application.