ECO – FRIENDLY PROTON BATTERY BASED ON PVA, PROLINE AND NH4NO3

Abstract

Eco-friendly proton-conducting solid polymer electrolytes were successfully developed using poly(vinyl alcohol) (PVA), proline, and ammonium nitrate (NH₄NO₃) through the solution casting technique. Polymer electrolyte membranes with different NH₄NO₃ concentrations (0.1–0.4 wt%) were prepared and characterized by using X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), AC impedance spectroscopy, transference number measurement and linear sweep voltammetry (LSV). XRD analysis revealed that the incorporation of NH₄NO₃ reduced the crystallinity of the PVA–proline matrix and enhanced its amorphous nature, while DSC results showed a significant decrease in the glass transition temperature, indicating improved polymer chain flexibility. FTIR spectra confirmed the complex formation and molecular interactions among PVA, Proline and NH₄NO₃. The polymer electrolyte containing 75 Mwt% PVA: 25 Mwt% Proline: 0.3 Mwt% NH₄NO₃ exhibited the highest ionic conductivity of 7.76 × 10⁻⁴ S cm⁻¹ at room-temperature with a low activation energy of 0.18 eV, demonstrating efficient proton transport. The electrolyte also exhibited a high ionic transference number (t₍ion₎ = 0.9753) and a wide electrochemical stability window of 3.23 V, confirming its suitability for electrochemical applications. A primary proton battery fabricated using the optimized polymer electrolyte delivered an open-circuit voltage of 1.73 V and maintained stable discharge characteristics. These findings demonstrate that the PVA–proline–NH₄NO₃ polymer electrolyte is a promising, biodegradable and environmentally friendly candidate for next-generation proton batteries and other solid-state electrochemical energy storage devices.