Synthesis and characterization of SrBi4Ti4O15ferroelectric filler based composite polymer electrolytes for lithium ion batteries

Composite polymer electrolytes (CPEs) based on poly (ethylene oxide) (PEO) (Mol.Wt ∼6×10⁵) complexed with LiN(CF₃SO₂)₂ lithium salt and SrBi₄Ti₄O₁₅ ferroelectric ceramic filler have been prepared as films. Citrate gel technique and conventional solid state technique were employed for the synthesis of the ferroelectric fillers in order to study the effect of particle size of the filler on ionic conductivity of the polymer electrolyte. Characterization techniques such as X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM) and temperature dependant DC conductivity studies were taken for the prepared polymer composite electrolytes. The broadening of DTA endotherms on addition of ceramic fillers to the polymer salt complex indicated the reduction in crystallinity. An enhancement in conductivity was observed with the addition of SrBi₄Ti₄O₁₅ as filler to the (PEO)₈-LiN(CF₃SO₂)₂ polymer salt complexes. Among the investigated samples (PEO)₈-LiN(CF₃SO₂)₂ +10 wt% SrBi₄Ti₄O₁₅ (citrate gel) polymer composite exhibits a maximum conductivity.     

A study on polymer blend electrolyte based on PVA/PVP with proton salt

Proton-conducting polymer blend electrolytes based on PVA–PVP–NH₄NO₃ were prepared for different compositions by solution cast technique. The prepared films are investigated by different techniques. The XRD study reveals the amorphous nature of the polymer electrolyte. The FTIR and laser Raman studies confirm the complex formation between the polymer and salt. DSC measurements show decrease in T _g with increasing salt concentration. The ionic conductivity of the prepared polymer electrolyte was found by ac impedance spectroscopy analysis. The maximum ionic conductivity was found to be 1.41 × 10^?3 S cm^?1 at ambient temperature for the composition of 50PVA:50PVP:30 wt% NH₄NO₃ with low-activation energy 0.29 eV. The conductivity temperature plots are found to follow an Arrhenius nature. The dielectric behavior was analyzed using dielectric permittivity (ε*) and the relaxation frequency (τ) was calculated from the loss tangent spectra (tan δ). Using this maximum ionic conducting polymer blend electrolyte, the primary proton battery with configuration Zn + ZnSO₄·7H₂O/50PVA:50PVP:30 wt% NH₄NO₃/PbO₂ + V₂O₅ was fabricated and their discharge characteristics studied.     

Dynamic Mechanical,DSC, and Electrical Investigations on Nano Al2O3 Filled PVA:NH4SCN:DMSO Polymer Composite Dried Gel Electrolytes

This paper reports the dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and ionic conductivity studies on nanosized Al₂O₃(aluminium oxide) filled PVA:NH₄SCN:DMSO polymer composite dried gel electrolytes prepared by the wet chemistry route. Better mechanical stability and thermal behavior are noticed in the composite system. Multiple relaxation peaks seen in tangent loss measurements (in DMA studies) have been suitably correlated. Enhancement in ionic conductivity has been noticed with an optimum value of 4.02 × 10^?3 Scm^?1 for 4 wt% nano Al₂O₃ filled composite electrolytes. Temperature dependence of ionic conductivity shows a combination of Arrhenius and VTF (Vogel-Tamman-Fulcher) behavior.     

Lithium difluoro(oxalate)borate‐based novel nanocomposite polymer electrolytes for lithium ion batteries

BACKROUND: HF formation and poor thermal stability found in commercial lithium ion batteries comprising LiPF₆ (and other salts) have hampered the replacement of LiPF₆. Therefore, a new kind of electrolyte salt is necessary to replace the one commercially available. RESULTS: A novel lithium difluoro(oxalate)borate (LiDFOB)‐based nanocomposite polymer electrolyte has been prepared in a matrix of poly[(vinylidene fluoride)‐co‐(hexafluoropropylene)] (PVdF‐HFP). The electrolyte contains ethylene carbonate and diethyl carbonate as plasticizers and nanoparticulate Sb₂O₃ as a filler. Membranes obtained by a solution casting technique were characterized by AC impedance, thermogravimetry and tensile strength measurements and morphological studies. Membranes with 5 wt% Sb₂O₃ exhibit a room‐temperature conductivity of 0.298 mS cm^?1, and are thermally stable up to ca 130 °C. Furthermore, the nanocomposite membranes show a 125% increase in mechanical stability as compared to filler‐free membranes. The structural change from α to β phases was confirmed by Raman studies. CONCLUSION: One of the important advantages of using LiDFOB lies in its bulkier DFOB anion, which also acts as solid plasticizer, thus improving the basic requirements of the electrolyte, such as mechanical and thermal stabilities, as well ionic conductivity and with a lower filler content. The overcharge tolerance of LiDFOB salt at higher temperature is also to be noted, because of the oxalate moieties. Preliminary investigations confirmed the possibility of using Sb₂O₃ nanoparticle‐filled membranes in industry in the near future. Copyright © 2008 Society of Chemical Industry     

Poly(methyl methacrylate) based nanocomposite gel polymer electrolytes with enhanced safety and performance

The study presents preparation of poly methyl methacrylate (PMMA) based nanocomposite gel polymer electrolytes consisting of, salt lithium perchlorate (LiClO₄), plasticizer PC/DEC and different proportions of SiO₂ nanofiber by solution casting process. The effect of the composition of the electrolytes on their ionic, mechanical and thermal characteristics was investigated. Morphology of the nanocomposite electrolyte films has been observed by scanning and transmission electron microscopes. Interactions among the constituents of the composite and structural changes of the base polymer were investigated by Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. The maximum conductivity i.e. 10^?3 Scm^?1 at room temperature is obtained with the electrolyte composition of 0.6(PMMA)-0.15(PC + DEC)-0.1LiClO₄ (wt%) containing 10 wt% SiO₂ nanofiber and the temperature dependent conductivity data of the electrolyte follows Vogel-Tamman-Fulcher (VTF) behavior.     

Morphology,crystallinity, and electrochemical properties of in situ formed poly(ethylene oxide)/TiO2 nanocomposite polymer electrolytes

A method to produce nanocomposite polymer electrolytes consisting of poly(ethylene oxide) (PEO) as the polymer matrix, lithium tetrafluoroborate (LiBF₄) as the lithium salt, and TiO₂ as the inert ceramic filler is described. The ceramic filler, TiO₂, was synthesized in situ by a sol–gel process. The morphology and crystallinity of the nanocomposite polymer electrolytes were examined by scanning electron microscopy and differential scanning calorimetry, respectively. The electrochemical properties of interest to battery applications, such as ionic conductivity, Li⁺ transference number, and stability window were investigated. The room‐temperature ionic conductivity of these polymer electrolytes was an order of magnitude higher than that of the TiO₂ free sample. A high Li⁺ transference number of 0.51 was recorded, and the nanocomposite electrolyte was found to be electrochemically stable up to 4.5 V versus Li⁺/Li. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2815–2822, 2003     

LiClO4 salt concentration effect on the properties of PVC‐modified low molecular weight LENR50‐based solid polymer electrolyte

A work was carried out on a solid polymeric electrolyte system comprising blends of poly (vinyl chloride) and liquid 50% epoxidized natural rubber (LENR50) as a polymer host with LiClO₄ as a salt and prepared by solution casting technique. In this paper, the main study was the effect of LiClO₄ salt concentration on the electrolyte properties. The effect of the salt on the electrolyte properties was characterized and analyzed with impedance spectroscopy (EIS), X‐ray diffraction (XRD), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM). The EIS result showed that highest ionic conductivity was obtained at 30 wt % salt with a value of 2.3 × 10^?8 S cm^?1. The XRD results revealed that the LiClO₄ salt was fully complexed within the polymer host as no sharp peaks were observed. However, above 30 wt % of salt, some sharp peaks were observed. This phenomenon was caused by the association of ions. Meanwhile, DSC analysis showed that T_g increased as the salt content increased. This implied that LiClO₄ salt had interaction with polymer host by forming coordination bond. The morphologies' studies showed that good homogeneity and compatibility of the electrolyte were achieved. Upon the addition of the salt, formation of micropores occurred. It was noted that micropores which aid in mobility of ions in the electrolyte system has increased the ionic conductivity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Ionic Conductivity and Discharge Characteristic Studies of PVA-Mg(CH3COO)2 Solid Polymer Electrolytes

Ion conducting solid polymer electrolytes based on a polymer polyvinyl alcohol (PVA) complexed with magnesium acetate (Mg(CH₃COO)₂) were prepared by solution cast technique. Various experimental techniques, such as XRD, DSC, composition-dependent conductivity, temperature-dependent conductivity, and transport number measurements are used to characterize these polymer electrolyte films. The transference number data indicated the dominance of ion-type charge transport in these polymer electrolyte systems. An electrochemical cell with the configuration Mg/(80PVA + 20Mg(CH₃COO)₂)/(I₂ + C + electrolyte) has been fabricated and its discharge characteristics were studied. The Open Circuit Voltage (OCV) is 1.84 V.     

1H NMR,thermal, and conductivity studies on PVAc based gel polymer electrolytes

The lithium‐ion conducting gel polymer electrolytes (GPE), PVAc‐DMF‐LiClO₄ of various compositions have been prepared by solution casting technique. ¹H NMR results reveal the existence of DMF in the gel polymer electrolytes at ambient temperature. Structure and surface morphology characterization have been studied by X‐ray diffraction analysis (XRD) and scanning electron microscopy (SEM) measurements. Thermal and conductivity behavior of polymer‐ and plasticizer‐salt complexes have been studied by differential scanning calorimetry (DSC), TG/DTA, and impedance spectroscopy results. XRD and SEM analyses indicate the amorphous nature of the gel polymer‐salt complex. DSC measurements show a decrease in T_g with the increase in DMF concentrations. The thermal stability of the PVAc : DMF : LiClO₄ gel polymer electrolytes has been found to be in the range of (30–60°C). The dc conductivity of gel polymer electrolytes, obtained from impedance spectra, has been found to vary between 7.6 × 10^?7 and 4.1 × 10^?4 S cm^?1 at 303 K depending on the concentration of DMF (10–20 wt %) in the polymer electrolytes. The temperature dependence of conductivity of the polymer electrolyte complexes appears to obey the VTF behavior. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanofiller on ion conductivity,transmittance, and glass transition temperature of PEI:LiTFSI:PC:EC polymer electrolytes

In the present study, ion conductivity, optical properties, and glass transition temperatures are characterized for polymer electrolytes composed of poly(ethyleneimine) (PEI), lithium bis(trifluoromethane)sulfonylimide (LiTFSI) salt, propylene carbonate (PC), and ethylene carbonate (EC). It was doped with nanoceramic particles in different ratio (0–15 wt.%) to see the effect of ceramic particles. The salt concentration was fixed as 1.04 mol.kg^?1. Although valuable improvement in ion conductivity could not be achieved due to nano-Al₂O₃ fillers, ion conductivity results are placed between 10^?2 and 10^?4 S/cm. Differential scanning calorimetry (DSC) measurements and optical measurements of all electrolytes were performed between ?80 and 140 °C, in the wavelength range between 400 and 700 nm for sample with 80 μm thickness, respectively. The results showed that transmittance of electrolytes decreased monotonically for increasing Al₂O₃ contents. In particular, its transmittance value at 550 nm where human sight is at its greatest sensitivity went from 100% without nanoparticles to 50% for 15 wt% of Al₂O₃.     

Synthesis, characterization and device application of hot-pressed solid polymer electrolytes:(1 − x) PEO:x NaHCO3

Synthesis and io n transport characterization of hot-pressed solid polymer electrolyte (SPE) membranes:(1 ? x) poly (ethylene oxide) (PEO):x NaHCO₃, where 0 < x < 50 wt.%, have been reported. SPE films have been synthesized using a hot-press technique in place of the traditional solution-cast method. A conductivity enhancement of the two orders of magnitude was achieved in SPE film:70PEO:30NaHCO₃ and this composition has been referred to as optimum conducting composition (OCC). Materials characterization was done with the help of XRD, SEM, FTIR, DSC and TGA techniques. The ion transport behavior in SPE membranes has been discussed on the basis of experimental measurements on their ionic conductivity (σ), ionic mobility (μ) and some other important parameters. A solid-state polymer battery was fabricated using SPE OCC at room temperature, as a device application.     

Electrochemical studies of electrospun organic/inorganic hybrid nanocomposite fibrous polymer electrolyte for lithium battery

Poly(vinylidene fluoride-co-hexafluoropropylene) P(VdF-co-HFP)/magnesium aluminate (MgAl₂O₄) hybrid fibrous nanocomposite polymer electrolyte membranes were newly prepared by electrospinning method. The as-prepared electrospun pure and nanocomposite fibrous polymer membranes with various MgAl₂O₄ filler contents were characterized by X ray diffraction, differential scanning calorimetry and scanning electron microscopy techniques. The fibrous nanocomposite polymer electrolytes were prepared by soaking the electrospun membranes in 1 M LiPF₆ in EC:DEC (1:1, v/v). The fibrous nanocomposite polymer electrolyte membrane with 5 wt.% of MgAl₂O₄ show high electrolyte uptake, enhanced ionic conductivity is found to be 2.80 × 10⁻³ S cm⁻¹ at room temperature and good electrochemical stability window higher than 4.5 V. Electrochemical performance of commercial celgard 2320, fibrous pure and nanocomposite polymer electrolyte (PE, NCPE) membranes with different MgAl₂O₄ filler content is evaluated in Li/celgard 2320, PE, NCPE/LiCoO₂ CR 2032 coin cells at current density 0.1 C-rate. The NCPE with 5 wt.% of MgAl₂O₄ delivers an initial discharge capacity of 158 mAhg⁻¹ and stable cycle performance compared with the other cells containing celgard 2320 separator and pure membrane.     

Ionic interactions and transport characteristics of a new polymer electrolyte system containing poly(propylene glycol) 4000 complexed with AgCF3SO3

The effect of concentration of AgCF₃SO₃ salt on the behavior of ionic transport within the polymer electrolyte system containing the polymer host poly(propylene glycol) of molecular weight 4000 (PPG4000) has been investigated in terms of spectroscopic and electrochemical properties. It is evident that the presence of well-defined interactions between the ether oxygens and silver cations arising due to the complexation of the silver salt with the polymer matrix has enabled the chosen polymer electrolyte system to possess the maximum room temperature (298 K) electrical conductivity of 9.4 × 10^?5 S cm^?1 in the case of the typical composition having the ether oxygen-to-metal ratio (O:M) of 4:1 and the lowest activation energy E _a of 0.46 eV for Ag⁺ ionic conduction.     

Li NMR spectroscopy and ion conduction mechanism of composite gel polymer electrolyte: A comparative study with variation of salt and plasticizer with filler

Microporous composite gel polymer electrolyte (CGPE) has been prepared by incorporating the home-made silica aerogel (SAG) particles into the poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) copolymer/LiClO₄ matrix. The ionic transport behavior of the electrolyte is studied with various experimental techniques such as AC impedance, X-ray diffraction (XRD), infrared (IR) spectra, nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA), etc. The results reveal that the SAG particles are well dispersed in the electrolytes and incorporate with the other components of the CGPEs. The solid-state ⁷Li NMR study has confirmed the interactions of lithium ion with SAG, polymer and plasticizers, causing to form the microporous structure and reduce the glass transition temperature and crystallinity, resulting in an increase in ionic conductivity of the CGPE. The best ionic conductivity (1.04 × 10⁻² S/cm at room temperature) is obtained from the composite polymer electrolyte containing 4 wt% of SAG, which is approximately four times higher than the ionic conductivity of the electrolyte without the filler.     

Studies of dielectric relaxation and a.c. conductivity in [(100−<Emphasis Type="Italic">x</Emphasis>)PEO + <Emphasis Type="Italic">x</Emphasis>NH<Subscript>4</Subscript>SCN]: Al-Zn ferrite nano composite polymer electrolyte

Present work deals with findings on dielectric behaviour and a.c. conduction in a ferrite doped polymer nano composite electrolyte system, namely [(100−x) PEO + xNH₄SCN]: ferrite. The formation of nano composite and structural behavior of electrolyte was studied by XRD and SEM images. The effect of salt and ferrite on conductivity behaviour of PEO based nano composite polymer electrolyte has been investigated by the impedance spectroscopy at room temperature. The variation of dielectric permittivity and dielectric loss with frequency was carried out at ambient temperature. The a.c. conductivity seems to follow the universal power law.     

Sulfonate based ionic liquid incorporated polymer electrolytes for Magnesium secondary battery

The polymer electrolytes comprising of PVdF-HFP/PVAc/Mg(ClO₄)₂ as salt based polymer blend electrolytes derived from the addition of varying amounts of 1-ethyl – 3-methylimidazolium trifluoromethane sulfonate [EMITF], as dopant were synthesized in the form of films by solution-casting method. The XRD and FTIR patterns confirm the formation of an amorphous phase and also that complex formation between the polymers, salt and ionic liquid. The SEM images show that the polymer electrolyte exhibit a enormous pores, remarkably, the maximum ionic conductivity is obtained in the case of the typical polymer system I₃ is found to be 9.122 × 10^?4 Scm^?1at 303 K.     

An efficient Sm and Ge co-doped ceria nanocomposite electrolyte for low temperature solid oxide fuel cells

In this study we present a new nanocomposite electrolyte based on samarium (Sm) and germanium (Ge) co-doped ceria Ce_0.7Sm_0.15Ge_0.15O_2-δ (SGeDC). The nanocomposite electrolyte was prepared using co-precipitation method. The crystal structure and surface morphology were determined using x-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Four probe dc conductivity indicated the value of 0.074 S/cm at 650 °C. The Fuel cell performance was carried out using hydrogen as fuel. The maximum OCV observed was 0.95 V while the peak power density came out to be 600 mW/cm² at 600 °C. It is suggested that adding Ge, the conductivity as well as performance of this new nanocomposite electrolyte is comparatively enhanced and it can find potential applications in low temperature solid oxide Fuel cells (LTSOFCs).     

Metallic-lithium, LiFePO4-based polymer battery using PEO—ZrO2 nanocomposite polymer electrolyte

A study of the electrochemical properties of a PEO-based polymer electrolyte with nanometric ZrO₂ as ceramic filler has been carried out in order to confirm an earlier reported model dealing with the role of ceramic fillers within PEO-based polymer electrolytes as components that enhance such properties as conductivity, lithium transference number, compatibility with lithium metal electrodes and cyclability. A prototype of a lithium polymer battery, based on a membrane made from a nanocomposite polymer electrolyte doped with ZrO₂, utilizing LiFePO₄ + 1%Ag as cathode, has been assembled and galvanostatically cycled, resulting in excellent performance at temperatures ranging from 100 °C to 60 °C (close to the crystallization temperature of PEO).     

Preparation and characterization of gel polymer electrolyte based on PVA-K2CO3

ABSTRACT

In this study, electrolyte materials were synthesized by mixing a highly conducting salt (K₂CO₃) with the poly(vinyl alcohol) (PVA) in different proportions (from 10 to 50 wt.%). The synthesized electrolyte was characterized using Fourier transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) for their functional groups, morphology, thermal stability, glass transition temperature (T_g ), ionic conductivity, and potential window, respectively. Characterization results show that the complex formation between PVA and K₂CO₃ salt has been established by FTIR spectroscopic study, which indicates the detailed interaction between PVA and the salts in PVA-K₂CO₃ composites while the amorphous nature of the electrolyte after incorporation of the salts has been confirmed by FESEM analysis. Similarly, TGA and DSC analysis revealed that both decomposition temperature and T_g of the synthesized electrolytes decrease with the addition of K₂CO₃ due to the strong plasticizing effect of the salt. The results confirm that the electrolytes have sufficient thermal stability for supercapacitor operation, as well as an amorphous phase to effectively deliver high ionic conductivity. The highest ionic conductivity of 4.53 × 10^?3 S cm^?1 at 373 K and potential window of 2.7 V was exhibited by PK30 (30 wt.% K₂CO₃), which can be considered as high value for solid-state electrolytes which are superior to those electrolytes from PVA salts earlier reported. The results similarly show that the prepared electrolyte is temperature-dependent as conductivity increase with increase in temperature. Based on these properties, it can be imply that the PVA-K₂CO₃ gel polymer electrolyte (GPE) could be a promising electrolyte candidate for EDLC applications. The results indicate that the PVA-K₂CO₃ as a new electrolyte material has great potential in practical applications of portable energy-storage devices.     

Polystyrene-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> composite solid polymer electrolyte for lithium secondary battery

In a common salt-in-polymer electrolyte, a polymer which has polar groups in the molecular chain is necessary because the polar groups dissolve lithium salt and coordinate cations. Based on the above point of view, polystyrene [PS] that has nonpolar groups is not suitable for the polymer matrix. However, in this PS-based composite polymer-in-salt system, the transport of cations is not by segmental motion but by ion-hopping through a lithium percolation path made of high content lithium salt. Moreover, Al₂O₃ can dissolve salt, instead of polar groups of polymer matrix, by the Lewis acid-base interactions between the surface group of Al₂O₃ and salt. Notably, the maximum enhancement of ionic conductivity is found in acidic Al₂O₃ compared with neutral and basic Al₂O₃ arising from the increase of free ion fraction by dissociation of salt. It was revealed that PS-Al₂O₃ composite solid polymer electrolyte containing 70 wt.% salt and 10 wt.% acidic Al₂O₃ showed the highest ionic conductivity of 9.78 × 10^-5 Scm^-1 at room temperature.