Salmiah Ibrahim

Characterization of PVDF-HFP-LiCF3SO3-ZrO2 Nanocomposite Polymer Electrolyte Systems

Nanocomposite polymer electrolytes were prepared by incorporating different amounts of zirconium oxide (ZrO2) nanofiller to poly(vinylidene fluoride-co-hexafluoropropylene)-lithium trifluoromethane sulfonate (PVDF-HFP-LiCF3SO3). X-ray diffraction (XRD) study has been carried out to investigate the structural features of the electrolyte films while a.c. impedance spectroscopy has been performed to investigate their electrical properties. The conductivity of nanocomposite polymer electrolyte systems is influenced by nanofiller concentration. The increase in conductivity is attributable to the increase in the fraction of amorphous region and the number of charge carriers and vice versa. The highest conductivity obtained is in the order of 10-3 S cm-1 for the system dispersed with 5 wt% of ZrO2 nanofiller.

Synthesis and characterization of castor oil-based polyurethane for potential application as host in polymer electrolytes

Polyurethane (PU) based on polyol, derived from castor oil has been synthesized and characterized for potential use as a base material for electrolytes. Transesterification process of castor oil formed a polyol with hydroxyl value of 190 mg KOH g−1 and molecular weight of 2786 g mol−1. The polyols together with 4,4′-diphenylmethane diisocyanate were used to synthesize the desired bio-based PU. The molecular structure of PU was investigated by Fourier transform infrared (FTIR) spectroscopy. The disappearance of NCO peak in the FTIR spectrum at 2270–2250 cm−1 showed that diisocyanate has completely reacted to form PU. Morphological characteristic of the PU film was analysed using scanning electron microscopy, whereas thermal characteristics of the materials were characterized using dynamic mechanical analysis and thermal gravimetric analysis. The cross-sectional micrograph showed that the prepared film was highly amorphous and homogeneous. Thermal studies revealed that the film had low glass transition temperature, −15.8°C, and was thermally stable up to 259°C. These observations indicated the synthesized PU possessed favourable properties to act as a base material in polymer electrolytes.

Polymer Electrolyte of PVDF-HFP/PEMA-NH4CF3So3-TiO2 and its Application in Proton Batteries

In this study, composite polymer electrolytes were prepared by addition of titanium oxide, TiO2 nanofiller into polyvinylidene fluoride-co-hexafluoropropylene/polymethyl methacrylate-ammonium triflate (PVDF-HFP/PEMA-NH4CF3SO3) complex. The effect of TiO2 on conductivity of the complex was examined using impedance spectroscopy. The highest room temperature conductivity of 1.32 × 10-3 S cm-1 was shown by the system containing 5 wt % of TiO2. This system was used for the fabrication of proton batteries with the configurations of (Zn + ZnSO4.7H2O + C + PTFE)/PVDF-HFP/PEMA-NH4CF3SO3-(5wt%)TiO2/(MnO2 + C + PTFE) and (Zn + ZnSO4.7H2O + C + PTFE)/PVDF-HFP/PEMA-NH4CF3SO3-(5wt%)TiO2/(MnO2 + PbO2 + C + PTFE). The performance of the batteries indicated potential application of the electrolyte system in proton batteries.

PVDF-HFP/PVC Blend Based Lithium Ion Conducting Polymer Electrolytes

Flexible free standing polymer electrolyte films have been successfully prepared using a blend of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly(vinyl chloride) (PVC) doped with lithium perchlorate (LiClO4). The conductivity of the film was influenced by salt concentration and the degree of crystallinity. An optimum room temperature conductivity obtained was 2.10 x 10-4 S cm-1 for PVDF-HFP/PVC containing 35 wt.% LiClO4. The temperature-dependent conductivity of the polymer films exhibited VTF-type behaviour.

PVDF-HFP-NH4CF3SO3-SiO2 Nanocomposite Polymer Electrolytes for Protonic Electrochemical Cell

This paper describes the preparation and characterization of proton conducting nanocomposite polymer electrolytes based a polyvinylidene fluoride-co-hexapropylene (PVDF-HFP) for protonic electrochemical cells. The electrolytes were characterized by Differential Scanning Calorimetry (DSC) and Impedance Spectroscopy (IS). It is observed that the crystallinity of the PVDF-HFP-NH4CF3SO3 system slightly increase upon addition of SiO2 nanofiller. The PVDF-HFP-NH4CF3SO3-SiO2 electrolytes reveals the existence of two conductivity maxima at 1 and 4 wt% of SiO2 concentration attributed to two percolation thresholds in the nanocomposite polymer electrolyte. The optimum value of conductivity of 1.07 × 10-3 S cm-1 is achieved for the nanocomposite polymer electrolyte film with 1 wt% SiO2. Protonic electrochemical cells was fabricated with a configuration Zn + ZnSO4.7H2O + PTFE (anode) | PVDF-HFP:NH4CF3SO3+SiO2 (electrolyte) | MnO2 + PTFE (cathode). The maximum open circuit voltage (OCV) is ~1.50 V and discharge characteristics of the cell were studied at different loads of resistances.

Thermal and Electrical Properties of PVDF-HFP-LiCF3SO3-ZrO2 Nanocomposite Solid Polymer Electrolytes

ZrO2 nano sized filler of different amounts is introduced into solid polymer electrolytes of PVDF-HFP-LiCF3SO3-ZrO2. It is observed that the conductivity of the electrolytes varies with ZrO2 content and temperature. The highest room temperature conductivity achieved is in the order of 10-3 S cm-1 which is an increase of seven orders of magnitude compared to the conductivity of PVDF-HFP-LiCF3SO3 (without filler). The temperature dependent conductivity follows the Vogel Tamman Fulcher relationship which can be described by the free volume theory. Transference number measurements using DC polarization method show that the nanocomposite polymer electrolytes are ionic conductors. Differential Scanning Calorimetry results show that the degree of crystallinity is slightly affected by the addition of ZrO2 nanofiller.