Characterization of a solid state battery based on polyblend of (PVP+PVA+KBrO3) electrolyte

A potassium ion conducting polyblend electrolyte based on polyvinyl pyrrolidone (PVP) + polyvinyl alcohol (PVA) complexed with KBrO₃ was prepared using solution-cast technique. The electrical conductivity and transference number measurements were performed to characterize the polyblend electrolyte for battery applications. These measurements have shown that the electrolyte is a mixed (ionic + electronic) conductor, the charge transport being mainly ionic (t_ion=0.97). Using the electrolyte, electrochemical cells with configurations K / (PVP+PVA+KBrO₃)/(I₂), K / (PVP+PVA+KBrO₃)/(I₂+C) and K/(PVP+PVA+KBrO₃) / (I₂+C+electrolyte) were fabricated and their discharge characteristics studied. The cell with configuration K / (PVP+PVA+KBrO₃) / (I₂+C+electrolyte) exhibited better discharge characteristics than the other configurations. The other cell parameters like open circuit voltage (OCV), short circuit current (SCC) etc. were evaluated and are reported. Paper presented at the 2nd International Conference of Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.     

Preparation and electrical characterization of (PVC + KBrO3) polymer electrolytes for solid state battery applications

This paper presents results of studies on dc electrical conductivity and transference number measurements on potassium bromate (KBrO₃) complexed polyvinyl chloride (PVC) films prepared by solution cast technique. Temperature dependence of dc electrical conductivity and transference number data indicated the dominance of ion type charge transport in these specimens. The magnitude of conductivity increased with increase in concentration of the salt and temperature. Using this (PVC + KBrO₃) electrolyte, solid-state electrochemical cells were fabricated, and their discharge profiles were studied under a constant load of 100 kΩ. Several cell profiles such as open circuit voltage, short circuit current, power density, and energy density associated with these cells were evaluated and were reported. The features of complexation of the electrolytes were studied by X-ray diffraction and Fourier transform infrared spectroscopy. Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006     

Effects of MnO<Subscript>2</Subscript> nano-particles on the conductivity of PMMA-PEO-LiClO<Subscript>4</Subscript>-EC polymer electrolytes

Li-ion rechargeable batteries based on polymer electrolytes are of great interest for solid state electrochemical devices nowadays. Many studies have been carried out to improve the ionic conductivity of polymer electrolytes, which include polymer blending, incorporating plasticizers and filler additives in the electrolyte systems. This paper describes the effects of incorporating nano-sized MnO₂ filler on the ionic conductivity enhancement of a plasticized polymer blend PMMA–PEO–LiClO₄–EC electrolyte system. The maximum conductivity achieved is within the range of 10⁻³ S cm⁻¹ by optimizing the composition of the polymers, salts, plasticizer, and filler. The temperature dependence of the polymer conductivity obeys the VTF relationship. DSC and XRD studies are carried out to clarify the complex formation between the polymers, salts, and plasticizer.     

Effect of ethylene carbonate plasticizer on agar-agar: NH<Subscript>4</Subscript>Br-based solid polymer electrolytes

Proton-conducting polymer electrolytes based on biopolymer, agar-agar as the polymer host, ammonium bromide (NH₄Br) as the salt and ethylene carbonate (EC) as the plasticizer have been prepared by solution casting technique with dimethylformamide as solvent. Addition of NH₄Br and EC with the biopolymer resulted in an increase in the ionic conductivity of polymer electrolyte. EC was added to increase the degree of salt dissociation and also ionic mobility. The highest ionic conductivity achieved at room temperature was for 50 wt% agar/50 wt% NH₄Br/0.3% EC with the conductivity 3.73?×?10^?4 S cm^?1. The conductivity of the polymer electrolyte increases with the increase in amount of plasticizer. The frequency-dependent conductivity, dielectric permittivity (ε′) and modulus (M′) studies were carried out.     

Preparation and characterization of blend polymer electrolyte film based on poly(vinyl alcohol)-poly(acrylonitrile)/MgCl<Subscript>2</Subscript> for energy storage devices

The development of magnesium electrolytes for battery applications has been the demand for electrochemical devices. To meet such demand, in this work solid blend polymer electrolytes were prepared using polyvinyl alcohol (PVA) and polyacrylonitrile (PAN) (92.5PVA:7.5PAN) as host polymer, magnesium chloride (MgCl₂) of different molar mass percentage (m.m.%) (0.1, 0.2, 0.3, 0.4, 0.5, and 0.6%) as salt and dimethylformamide (DMF) as solvent. Structural, vibrational, thermal, electrical, and electrochemical properties of the prepared electrolytes were investigated using different techniques such as X-ray diffraction pattern, FTIR spectroscopy analysis, differential scanning calorimetry (DSC), AC impedance measurement, and transference number measurement. X-ray diffraction studies confirm the minimum volume fraction of crystalline phase for the polymer electrolyte with 0.5 m.m.% of MgCl₂. FTIR confirms the complex formation between host polymer and salt. DSC analysis proves the thermal transition of the prepared films are affected by salt concentration. The optimized material with 0.5 m.m.% of MgCl₂ offers a maximum electrical conductivity of 1.01 × 10^?3 S cm^?1 at room temperature. The Mg²⁺ ion conduction in the blend polymer electrolyte is confirmed from transference number measurement. Electrochemical analysis demonstrates the promising characteristic of these polymer films suitable as electrolytes for primary magnesium batteries. Output potential and discharge characteristics have been analyzed for primary magnesium battery which is constructed using optimized conducting electrolyte.     

Cells studies on PEO/PEG/NaClO<Subscript>3</Subscript> thin-film electrolyte system based on composite V<Subscript>2</Subscript>O<Subscript>5</Subscript> electrode

The thin-film solid polymer electrolyte based on polyethylene oxide (PEO) with sodium chlorite (NaClO₃) has been prepared by a solution-cast technique. The electrolyte was characterized by X-ray diffraction (XRD), infrared (IR), cyclic voltammetry, alternating current conductivity, and Wagner’s polarization studies. The complexation of NaClO₃ with PEO was confirmed through the XRD and IR studies. The transference number measurement has shown that the ion transport is predominant over electrons in the polymer electrolytes (t _ions ≈ 0.94). The conductivity enhancement was observed in the case of the PEO/NaClO₃ system with the addition of plasticizers (low-molecular-weight polyethylene glycol, organic solvents propylene carbonate and dimethyl formamide. Cyclic voltammetry analysis showed the stability and redox character of the electrolyte and electrode. Finally, polymer electrolyte systems were examined by electrochemical cell studies using V₂O₅ and composite V₂O₅ cathode at temperature of 35 °C. Overall, the plasticized electrolyte shows a better electrochemical performance, and a higher discharge capacity was observed in composite V₂O₅-based cells over V₂O₅-based cells.     

Effect of nano-dispersed silica on the ion-conducting behavior of PMMA-based polymer gel electrolytes containing LiPF<Subscript>6</Subscript>

Nano-sized silica poly(methylmethacrylate)-based gel electrolyte containing lithium hexafluorophosphate (LiPF₆) was synthesized by using different binary solvent mixture (propylene carbonate(PC) and dimethylformamide (DMF) in different volume ratio). Role of DMF in PC: Higher DMF content in PC-based electrolyte shows higher ionic conductivity at all polymer content and at wide temperature regions (10-70 °C). A small increment in ionic conductivity at lower content of polymer in liquid/gel electrolyte was observed and having maximum conductivity of 13.12 mS/cm at 25 °C. Stability (mechanically and electrically), viscosity and ionic conductivity of gel electrolytes were improved with the addition of nano-sized silica at ambient temperature. Ionic conductivity of nano-sized silica-based gel electrolyte does not change much over 5^o–70 °C temperature range and is factor-wise only which make indispensable in different electrochemical devices. Also polymer gel electrolyte membranes as such and with dispersed silica nano-particles were characterized through scanning electron microscope to study the morphology of gel matrix.     

Ionic transport, thermal, XRD, and phase morphological studies on LiCF3SO3-based PVC–PVdF gel electrolytes

The plasticized polymer electrolyte composed of polyvinylchloride (PVC) and polyvinylidene fluoride (PVdF) as host polymer, the mixture of ethylene carbonate and propylene carbonate as plasticizer, and LiCF₃SO₃ as a salt was studied. The effect of the PVC-to-PVdF blend ratio with the fixed plasticizer and salt content on the ionic conduction was investigated. The electrolyte films reveal a phase-separated morphology due to immiscibility of the PVC with plasticizer. Among the three blend ratios studied, 3:7 PVC–PVdF blend ratio has shown enhanced ionic conductivity of 1.47 × 10⁻⁵ S cm⁻¹ at ambient temperature, i.e., the ionic conductivity decreased with increasing PVC-to-PVdF ratio and increased with increasing temperature. A temperature dependency on ionic conductivity obeys the Arrhenius behavior. The melting endotherms corresponding to vinylidene (VdF) crystalline phases are observed in thermal analysis. Thermal study reveals the different levels of uptake of plasticizer by VdF crystallites. The decrease in amorphousity with increase in PVC in X-ray diffraction studies and larger pore size appearance for higher content of PVC in scanning electron microscopy images support the ionic conductivity variations with increase in blend ratios.     

NH<Subscript>4</Subscript>NO<Subscript>3</Subscript> as charge carrier contributor in glycerolized potato starch-methyl cellulose blend-based polymer electrolyte and the application in electrochemical double-layer capacitor

Potato starch (PS)-methyl cellulose (MC) blend solid biopolymer electrolytes infused with ammonium nitrate (NH₄NO₃) and glycerol as plasticizer are made via the solution cast technique. Fourier transform infrared (FTIR) spectroscopy indicates that NH₄NO₃ has interacted with the polymer blend host. The addition of 40 wt% glycerol in the highest conducting plasticizer free electrolyte has improved the conductivity to the order of ～10^?3 S cm^?1. The thermal stability of the electrolytes is identified by thermogravimetric analysis (TGA). Result from X-ray diffraction (XRD) analysis shows that the electrolyte with maximum conductivity value has the lowest degree of crystallinity. Differential scanning calorimetry (DSC) analysis reveals that the highest conducting plasticized electrolyte possesses the lowest glass transition temperature (T _g) of ?27.5 °C. Conductivity trend is further verified by dielectric analysis. Transference numbers of ion (t _ion) and electron (t _e) for the highest conducting electrolyte are identified to be 0.98 and 0.02, respectively, confirming that ions are the dominant charge carriers. Linear sweep voltammetry (LSV) evaluates that the potential window for the electrolyte is 1.88 V. The internal resistance of the electrochemical double-layer capacitor (EDLC) is between 29 and 64 Ω. From the charged-discharged measurement, the value of C _s is 31 F g^?1. The EDLC is stable over 1000 cycles.     

Effect of ethylene carbonate plasticizer and TiO<Subscript>2</Subscript> nanoparticles on 49% poly(methyl methacrylate) grafted natural rubber-based polymer electrolyte

The effect of plasticizer and TiO₂ nanoparticles on the conductivity, chemical interaction and surface morphology of polymer electrolyte of MG49–EC–LiClO₄–TiO₂ has been investigated. The electrolyte films were successfully prepared by solution casting technique. The ceramic filler, TiO₂, was synthesized in situ by sol-gel process and was added into the MG49–EC–LiClO₄ electrolyte system. Alternating current electrochemical impedance spectroscopy was employed to investigate the ionic conductivity of the electrolyte films at 25 °C, and the analysis showed that the addition of TiO₂ filler and ethylene carbonate (EC) plasticizer has increased the ionic conductivity of the electrolyte up to its optimum level. The highest conductivity of 1.1 × 10⁻³ Scm⁻¹ was obtained at 30 wt.% of EC. Fourier transform infrared spectroscopy measurement was employed to study the interactions between lithium ions and oxygen atoms that occurred at carbonyl (C=O) and ether (C-O-C) groups. The scanning electron microscopy micrograph shows that the electrolyte with 30 wt.% EC posses the smoothest surface for which the highest conductivity was obtained.     

PVC–PMMA composite electrospun membranes as polymer electrolytes for polymer lithium-ion batteries

Composite nanofibrous membranes based on poly (vinyl chloride) (PVC)?Cpoly (methyl methacrylate) (PMMA) were prepared by electrospinning and then they were soaked in liquid electrolyte to form polymer electrolytes (PEs). The introduction of PMMA into the PVC matrix enhanced the compatibility between the polymer matrix and the liquid electrolyte. The composite nanofibrous membranes prepared by electrospinning involved a fully interconnected pore structure facilitating high electrolyte uptake and easy transport of ions. The ion conductivity of the PEs increased with the increase in PMMA content in the blend and the ion conductivity of the polymer electrolyte based on PVC?CPMMA (5:5, w/w) blend was 1.36?×?10^?3 S cm^?1 at 25?°C. The polymer electrolyte based on PVC?CPMMA (5:5, w/w) blend presented good electrochemical stability up to 5.0?V (vs. Li/Li⁺) and good interfacial stability with the lithium electrode. The promising results showed that nanofibrous PEs based on PVC?CPMMA were of great potential application in polymer lithium-ion batteries.     

Performance evaluation of PVdF gel polymer electrolytes

A series of gel polymer electrolytes containing PVdF as homo polymer, a mixture of 1:1 Ethylene Carbonate (EC) : Propylene Carbonate (PC) as plasticizer and lithium-bistrifluoromethane sulphone imide [imide — LiN (CF₃SO₂)₂] has been developed. Amounts of polymer (PVdF), plasticizer and the imide lithium salt have been varied as a function of their weight ratio composition in this regard. Dimensionally stable films possessing appreciable room temperature conductivity values have been obtained with respect to certain weight ratio compositions. However, conductivity data have been recorded at different possible temperatures, i.e., from 20 °C to 65 °C. XRD and DSC studies were carried out to characterize the polymer films for better amorphicity and reduced glass transition temperature, respectively. The electrochemical interface stability of the PVdF based gel polymer electrolytes over a range of storage period (24 h – 10 days) have been investigated using A.C. impedance studies. Test cells containing Li/gel polymer electrolyte (GPE)/Li have been subjected to undergo 50 charge-discharge cycles in order to understand the electrochemical performance behaviour of the dimensionally stable films of superior conductivity. The observed capacity fade of less than 20% even after 50 cycles is in favour of the electrochemical stability of the gel polymer electrolyte containing 27.5% PVdF −67.5 % EC+PC −5% imide salt. Cyclic voltammetry studies establish the possibility of a reversible intercalation — deintercalation process involving Li⁺ ions through the gel polymer electrolyte.     

Discharge characteristics of polymer blend (PVP/PVA) electrolyte films doped with potassium bromide

Solid polymer blend electrolyte films based on PVP/PVA complexed with KBr were prepared by the solution cast technique. Various experimental techniques such as electrical conductivity and transport number measurement were used to characterize the polymer electrolyte films. Electrochemical cells with the polymer electrolytes (PVP + PVA + KBr) were fabricated in the configuration K / (PVP + PVA + KBr) / (I₂ + C + electrode). The discharge characteristics of the cells were studied under a constant load of 100 KΩ. The open-circuit voltage, short-circuit current, and discharge time for the plateau region are measured. Several other cell parameters were evaluated and are reported.     

Incorporation of NH<Subscript>4</Subscript>NO<Subscript>3</Subscript> into MC-PVA blend-based polymer to prepare proton-conducting polymer electrolyte films

Proton-conducting solid polymer blend electrolytes based on methylcellulose-polyvinyl alcohol:ammonium nitrate (MC-PVA:NH₄NO₃) were prepared by the solution cast technique. The structural and electrical properties of the samples were examined by X-ray diffraction (XRD), Fourier transform infrared (FTIR), and electrical impedance (EI) spectroscopy. The shifting and change in the intensity of FTIR bands of the electrolyte samples confirm the complex formation between the MC-PVA polymer blend and the NH₄NO₃ added salt. The observed broadening in the XRD pattern of the doped samples reveals the increase of the amorphous fraction of polymer electrolyte samples. The increase in electrical conductivity of polymer electrolyte samples with increasing salt concentration attributed to the formation of charge-transfer complexes, and to increase in the amorphous domains. A maximum ionic conductivity of about 7.39 × 10^?5 S cm^?1 was achieved at room temperature for the sample incorporating 20 wt% of NH₄NO₃. The DC conductivity of the present polymer system exhibits Arrhenius-type dependence with temperature. The decrease in the values of activation energies with increasing salt concentration indicates the ease mobility of ions. The decrease in dielectric constant with increasing frequency was observed at all temperatures. Optical properties such as absorption edge, optical band gap, and tail of localized state were estimated for polymer blend and their electrolyte films. It was found that the optical band gap values shifted towards lower photon energy from 6.06 to 4.75 eV by altering the NH₄NO₃ salt content.     

Effect of dibutyl phthalate as plasticizer on high-molecular weight poly(vinyl chloride)–lithium tetraborate-based solid polymer electrolytes

A series of different composition of polymer electrolytes-based on poly(vinyl chloride) (PVC) as host polymer, lithium tetraborate (Li₂B₄O₇) as dopant salt, and dibutyl phthalate (DBP) as plasticizer were prepared by solution casting method. The interaction between the PVC, Li₂B₄O₇, and DBP were studied by Fourier transform infrared. The shifting, broadening, and splitting of transmission peaks were the evidences of complexation. The highest ionic conductivity polymer electrolyte of 2.83 × 10⁻⁶ S/cm was achieved at ambient temperature upon addition of 30 wt.% of DBP. In addition, the temperature-dependent conductivity, frequency-dependent conductivity, dielectric permittivity, and modulus studies were performed. The temperature-dependent conductivity of the polymer electrolytes was found to obey the Arrhenius behavior. The thermal stability of polymer electrolytes was verified by thermogravimetric analysis. The lower in glass transition temperature was proven in differential scanning calorimetry, whereas the higher amorphous region within the polymer matrix was demonstrated in X-ray diffraction.     

Effect of polysorbate plasticizer on the structural and ion conduction properties of PEO–NH<Subscript>4</Subscript>PF<Subscript>6</Subscript> solid polymer electrolyte

Effects of a new plasticizer, polysorbate 80, on the structural and electrochemical properties of PEO–NH₄PF₆ polymer electrolyte system have been investigated. X-ray diffraction studies show significant increase in amorphicity of the solid polymer electrolyte on introduction of the plasticizer, which is also supported by lesser-dense spherulites observed in the SEM micrographs. The room temperature ionic conductivity of the electrolyte shows an increase of about two orders of magnitude (σ_max～10^?5 S/cm) on plasticization. The frequency dependence of the conductivity has been found to obey the Jonscher’s power law and slower backward ion hopping on plasticization. The polymer electrolyte shows protonic conduction as confirmed using cyclic voltammetry study. The studies show that polysorbate 80 is a promising plasticizer for semicrystalline polymer electrolytes.     

Influence of pyrazole on the photovoltaic performance of dye-sensitized solar cell with polyvinylidene fluoride polymer electrolytes

We investigate the influence of the pyrazole content on the polyvinylidene fluoride (PVDF)/KI/I₂ electrolytes for dye-sensitized solar cells (DSSCs). The solid polymer electrolyte films consisting of different weight percentage ratios (0 20, 30, 40, and 50 %) of pyrazole doped with PVDF/KI/I₂ have been prepared by solution casting technique using N,N-dimethyl formamide (DMF) as a solvent. The as-prepared polymer electrolyte films were characterized by various techniques such as Fourier transform infrared spectroscopy (FT-IR spectroscopy), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), alternate current (AC)-impedance analysis, and scanning electron microscopy (SEM). The 40 wt% pyrazole-PVDF/KI/I₂ electrolyte exhibited the highest ionic conductivity value of 9.52?×?10^?5 Scm^?1 at room temperature. This may be due to the lower crystallinity of PVDF and higher ionic mobility of iodide ions in the electrolyte. The DSSC fabricated using this highest ion conducting electrolyte showed an enhanced power conversion efficiency of 3.30 % under an illumination of 60 mW/cm² than that of pure PVDF/KI/I₂ electrolyte (1.42 %).     

Vibrational,electrical, and ion transport properties of PVA-LiClO<Subscript>4</Subscript>-sulfolane electrolyte with high cationic conductivity

Novel solid polymer electrolytes, poly(vinylalcohol)-lithium perchlorate (PVA-LiClO₄) and PVA-LiClO₄-sulfolane are prepared by solvent casting method. The experimental results show that sulfolane addition enhances the ionic conductivity of PVA-LiClO₄ complex by three orders. The maximum ionic conductivity of 1.14 ± 0.20 × 10^?2 S cm^?1 is achieved for 10 mol% sulfolane-added electrolyte at ambient temperature. Polymer-salt-plasticizer interactions are analyzed through attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. Lithium ion transference number is found by AC impedance spectroscopy combined with DC potentiostatic measurements. The results confirm that sulfolane improves the Li⁺ transference number of PVA-LiClO₄ complex to 0.77 from 0.40. The electrochemical stability window of electrolytes is determined by cyclic voltammetry (CV). The broad electrochemical stability window of 5.45 V vs. lithium is obtained for maximum conducting electrolyte. All-solid-state cell is fabricated using maximum conducting electrolyte, and electrochemical impedance study is carried out. It reveals that electrolyte interfacial resistance with Li electrode is very low. The use of PVA-LiClO₄-sulfolane as a viable electrolyte material for high-voltage lithium ion batteries is ensured.     

Investigation on compositional effect of PEG:BaTiO<Subscript>3</Subscript> in plasticized PVC–LiBETi polymer composite electrolytes

The blend-based polymer electrolyte comprising poly(vinyl chloride) (PVC) and poly(ethylene glycol) (PEG) as host polymer and lithium bis(perfluoroethanesulfonyl)imide as complexing salt have been prepared. Ethylene carbonate and dimethyl carbonate (50:50 v/v) are used as plasticizer for the system. The barium titanate is used as a filler, and the ratio of (PEG:BaTiO₃) is varied to study its effect on the conductivity behavior of the electrolyte. XRD and ac impedance studies are carried out on the prepared samples. The ac impedance measurements show that the conductivity of the prepared samples depends on the (PEG:BaTiO₃) ratio, and its value is higher for (15:5) wt.% of (PEG:BaTiO₃)-incorporated film. The temperature dependence of the conductivity of the polymer films obeys VTF relation. The role of ferroelectric filler in enhancing the conductivity is studied. The thermal stability of the film is ascertained from TG/DTA studies. The phase morphological study reveals that the porous nature of the polymer electrolyte membranes depends on the (PEG:BaTiO₃) ratio.     

Effect of plasticizer on microstructure and electrical properties of a sodium ion conducting composite polymer electrolyte

A plasticized composite polymer electrolyte (PCPE) based on Poly (ethylene oxide) + NaI with Na₂SiO₃ as the ceramics filler and Poly (ethylene glycol) as the plasticizer has been prepared by solution cast technique. Effect of plasticization on microstrucutre and electrical properties of the materials has been investigated. The changes in the structural and microstructural properties of the material have been investigated by XRD and SEM studies. The electrical conductivity estimated using a. c. impedance spectroscopy was found to be dependent on plasticizer concentration. An enhancement in the ionic conductivity value by three times has been recorded on addition of plasticizer when compared with that of unplasticized composite polymer electrolyte. The temperature dependence of conductivity of the polymer films is found to obey the Arrhenius behavior below and above the melting temperature of PEO. The electrical transport has been found to be a thermally activated process with ions being the predominant charge carrier.