Facile synthesis of PVA-formamide based solid state electrolyte membrane: A combined experimental and computational studies

For ever-growing energy demand, it is the imperative of time to develop advanced electrolyte materials which are compatible with Li + ion mobility in Lithium based batteries. In this study, polyvinyl alcohol (PVA)-LiNO3-Formamide (PLF) membrane complex has been developed for cost effective and mass fabrication of Li ion based energy storage devices. Improved Li + ion conducting PVA based polymer electrolytes in seven different PVA and LiNO3 blend compositions were prepared and characterized. Incorporation of Formamide (0.5 g) as plasticizer in the PVA-LiNO3 polymer matrix leads to a remarkable improvement in ionic conductivity (4.18 × 10⁻⁴ Scm⁻¹) for a 0.27 g of LiNO₃ concentration at ambient temperature. Improvement in Li conductivity is due to change in crystalline nature as a consequence of PVA O-H—O intra/inter molecular H-bonding destabilization. Investigation on the trend of activation energy as a function of dopant concentration indicates that the activation energy decreases up to 0.27 g of LiNO₃. Lowest activation energy 0.21 eV is observed for this concentration. More interestingly, improved Lithium Transference Number (LITN) of 0.437 is obtained through Bruce-Vincent approach for the plasticized optimum conducting membrane (PLF4–0.27 g LiNO₃ concentration) which is better than that of the commercially available Li batteries. Underlying molecular level interactions in the models of PVA and its complexes were explored using M05-2×/6–31 + G (d,f) levels of theory and NCI analysis. From the least interaction energy of PVA-Formamide complex, it is inferred that metal-Oxygen coordination contributes much for the stabilization of PVA-LiNO₃-Formamide, PVA-LiNO₃, Formamide-LiNO₃ complexes.