Conductive bio-polymer electrolyte iota-carrageenan with ammonium nitrate for application in electrochemical devices

Bio-polymer electrolyte iota-carrageenan (I-carrageenan) with ammonium nitrate (NH4NO3) has been prepared by solution-casting technique. The increase in amorphous nature of the bio-polymer electrolyte due to the addition of salt has been confirmed by X-ray diffraction analysis. From the XRD spectra, the average particle size has been calculated using the Debye-Scherrer formula and the value is 0.98 nm. The complex formation between the polymer and the salt has been confirmed by Fourier transform infra-red spectroscopy. The glass transition temperature of the bio-polymer I-carrageenan with NH4NO3 electrolytes has been found using differential scanning calorimetric technique. From the AC impedance spectroscopic analysis, the ionic conductivity value has been found to be 1.46 x 10(-3) S/cm at ambient temperature for the composition of 1.0 g I-carrageenan: 0.4 wt% NH4NO3. The temperature dependent conductivity of the polymer electrolyte obeys an Arrhenius relationship. The dielectric behavior has been analyzed using dielectric permittivity (epsilon*) and the relaxation frequency (tau) has been calculated from the loss tangent spectra (tan delta). The modulus spectra indicate non-Debye nature of the material. Ionic transference number has been found to be 0.95 for the polymer 1.0 g I-carrageenan: 0.4 wt% NH4NO3. The result reveals that the conducting species are predominantly due to ions. Electrochemical stability window of 2.46 V has been measured by using linear sweep voltammetry for the highest ionic conducting membrane. A primary proton battery has been constructed with the highest conductivity sample and open circuit voltage has been found to be 1.04 V. Fuel cell has been constructed with the highest proton conductivity polymer 1.0 g I-carrageenan: 0.4 wt% NH4NO3 and the open circuit voltage found to be 442 mV.