Amorphous Nature Of Polymer Electrolytes Research Articles

Organic dopant added polyvinylidene fluoride based solid polymer electrolytes for dye-sensitized solar cells

The effect of phenothiazine (PTZ) as dopant on PVDF/KI/I2 electrolyte was studied for the fabrication of efficient dye-sensitized solar cell (DSSC). The different weight percentage (wt%) ratios (0, 20, 30, 40 and 50%) of PTZ doped PVDF/KI/I2 electrolyte films were prepared by solution casting method using DMF as a solvent. The following techniques such as Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), X-ray diffractometer (XRD) and AC-impedance analysis have been employed to characterize the prepared polymer electrolyte films. The FT-IR studies revealed the complex formation between PVDF/KI/I2 and PTZ. The crystalline and amorphous nature of polymer electrolytes were confirmed by DSC and XRD analysis respectively. The ionic conductivities of polymer electrolyte films were calculated from the AC-impedance analysis. The undoped PVDF/KI/I2 electrolyte exhibited the ionic conductivity of 4.68×10−6Scm−1 and this value was increased to 7.43×10−5Scm−1 when PTZ was added to PVDF/KI/I2 electrolyte. On comparison with different wt% ratios, the maximum ionic conductivity was observed for 20% PTZ-PVDF/KI/I2 electrolyte. A DSSC assembled with the optimized wt % of PTZ doped PVDF/KI/I2 electrolyte exhibited a power conversion efficiency of 2.92%, than the undoped PVDF/KI/I2 electrolyte (1.41%) at similar conditions. Hence, the 20% PTZ-PVDF/KI/I2 electrolyte was found to be optimal for DSSC applications.

New solid polymer electrolytes (PEO20–LiTDI–SN) for lithium batteries: structural, thermal and ionic conductivity studies

Solid polymer electrolyte films based on Poly(ethylene oxide) (PEO) have been prepared by solution casting technique using acetonitrile as a solvent. Succinonitrile (SN) was used as a plasticizer and lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI) as a doping salt. The following techniques such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermo gravimetric analysis, AC-impedance analysis and linear sweep voltametry have been employed to characterize the prepared solid polymer electrolyte films. The crystalline and amorphous nature of polymer electrolytes was confirmed by XRD and DSC analysis respectively. The electrolyte film with 30 wt% of SN was thermally stable up to 260 °C. The ionic conductivities of polymer electrolyte films were calculated from the AC-impedance analysis. The undoped PEO20–LiTDI electrolyte exhibited the ionic conductivity of 9.64 × 10−7 S cm−1 and this value was increased to 2.83 × 10−5 S cm−1 when 30 wt% of succinonitrile was added to PEO20–LiTDI electrolyte at 23 °C. The temperature dependent conductivity obeys Arrhenius behavior and the activation energy decreased to 0.264 eV. The electrochemical stability of the optimum conducting composition is 4.3 V, which make it attractive as electrolyte for Li battery.

Characterization of proton conducting polymer blend electrolytes based on PVdF-PVA

The polymer electrolytes composed of poly (vinylidene fluoride) PVdF and poly (vinyl alcohol) PVA with various ratios of ammonium thiocyanate(NH4SCN) salt have been prepared by solution casting method. The increase in amorphous nature of polymer electrolytes has been confirmed by XRD analysis. The polymers-salt interactions have been analysed by FTIR spectroscopy. The Scanning Electron Micrographs affirm the smooth morphology of the polymer electrolytes. A shift in glass transition temperature (Tg) of the electrolytes has been observed from the DSC thermograms which indicates the interaction between polymers and salt. The conductivity and dielectric measurements are carried out on these films as a function of frequency at various temperatures. From the complex impedance spectroscopy, the conductivity is found to increase in the order of 10−9 to 10−3 S/cm at room temperature with the increase in salt concentration. The ionic transference number of the mobile ions has been estimated by Wagner's polarization method and the results reveal that the conducting species are predominantly due to ions.