Study on ammonium acetate salt-added polyvinyl alcohol-based solid proton-conducting polymer electrolytes

Polyvinyl alcohol (PVA) complexes with different compositions of ammonium acetate (AA) are prepared by solution cast technique. Polyvinyl alcohol crystallinity decreased with increasing ammonium acetate salt content. Molecular weight and density of polyvinyl alcohol complex increased with the addition of ammonium acetate salt. The ammonium acetate salt addition resulted in plasticization and hence decreased glass transition temperature (T (g)) as well as hardness number (HV). 80PVA:20AA presented maximum conductivity (sigma = 1.3 x 10(-7)S cm(-1) at 303 K) with minimum activation energy (E (a)) 0.151 eV below the T (g). The proton transport number determined using EMF method found a parts per thousand 0.98 for polymer complex with ammonium acetate content > 15 mol%. The complex impedance is measured as a function of frequency, temperature, relative humidity, and hydrogen partial pressure. Enhanced bulk conductivity with increased H-2 partial pressure and relative humidity suggested H+ mobility within complex polymer electrolyte.