Microstructural, dielectric, and transport properties of proton-conducting solid polymer electrolyte for battery applications

Poly (vinyl alcohol) (PVA) complexed with ammonium chloride (NH₄Cl) solid polymer electrolyte films was prepared using solution casting technique. Complexation of dopant with polymer was studied using Fourier transform infrared spectroscopy (FTIR). X-ray diffraction (XRD) results reflect that degree of crystallinity of the polymer increases with doping level. Surface morphology and topology of the electrolyte were studied using Scanning electron microscopy (SEM) and atomic force microscopy (AFM). Thermogravimetric analysis (TGA) results accounts for the increase of thermal stability of PVA due to the incorporation of NH₄Cl. Impedance analysis was carried out to understand relaxation phenomena of polymer electrolyte. Dielectric studies revealed that the mobility of charge carriers follows non-Debye nature of ionic relaxation. Electrical studies reveal that proton conduction occurs in this polymer electrolyte through Grotthus mechanism and maximum conductivity of the polymer electrolyte (7.5 wt% NH₄Cl/PVA) has been observed to be 1.81 × 10⁻³ S/cm at 353 K. Transport parameters have been determined using Wagner’s polarization technique. The observed highest conductivity of polymer electrolyte indicates utilizing this electrolyte for the fabrication of proton battery applications, and accordingly, the cell parameters have been measured.